path: root/ecos/packages/io/common/current/doc/io.sgml

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<PART id="io">
<TITLE>I/O Package (Device Drivers)</TITLE>

<!-- {{{ Intro -->

<CHAPTER id="io-package-intro">
<TITLE>Introduction</TITLE>

<PARA>
The I/O package is designed as a general purpose framework for
supporting device drivers. This includes all classes of
drivers from simple serial to networking stacks and beyond.
</PARA>

<PARA>
Components of the I/O package, such as device drivers, are
configured into the system just like all other components.
Additionally, end users may add their own drivers to this set.
</PARA>

<PARA>
While the set of drivers (and the devices they represent) may be
considered static, they must be accessed via an opaque
&ldquo;handle&rdquo;. Each device in the system has a unique name and
the <FUNCTION>cyg_io_lookup()</FUNCTION> function is used to map that
name onto the handle for the device. This &ldquo;hiding&rdquo; of the
device implementation allows for generic, named devices, as well as
more flexibility. Also, the <FUNCTION>cyg_io_lookup()</FUNCTION>
function provides drivers the opportunity to initialize the device
when usage actually starts.
</PARA>

<PARA>
All devices have a name. The standard provided devices use names such
as <filename>&ldquo;/dev/console&rdquo;</filename> and
<filename>&ldquo;/dev/serial0&rdquo;</filename>, where the
<filename>&ldquo;/dev/&rdquo;</filename> prefix indicates that this is
the name of a device.
</PARA>

<PARA>The entire I/O package API, as well as the standard
set of provided drivers, is written in C. </PARA>

<PARA>Basic functions are provided to send data to and receive data
from a device. The details of how this is done is left to the device [class] itself.
For example, writing data to a block device like a disk drive may
have different semantics than writing to a serial port. </PARA>

<PARA>Additional functions are provided to manipulate the state
of the driver and/or the actual device. These functions
are, by design, quite specific to the actual driver. </PARA>

<PARA>This driver model supports layering; in other words, a device
may actually be created &ldquo;on top of&rdquo; another device.
For example, the &ldquo;tty&rdquo; (terminal-like) devices are
built on top of simple serial devices. The upper layer then has
the flexibility to add features and functions not found at the lower
layers. In this case the &ldquo;tty&rdquo; device provides
for line buffering and editing not available from the simple serial
drivers.
</PARA>

<PARA>Some drivers will support visibility of the layers they depend
upon. The &ldquo;tty&rdquo; driver allows information about
the actual serial device to be manipulated by passing get/set
config calls that use a serial driver &ldquo;key&rdquo; down
to the serial driver itself. </PARA>

</CHAPTER>

<!-- }}} -->
<!-- {{{ User API -->

<CHAPTER id="io-user-api">
<TITLE><!-- <index></index> -->User API</TITLE>

<PARA>
All functions, except <FUNCTION>cyg_io_lookup()</FUNCTION>
require an I/O &ldquo;<!-- <index></index> -->handle&rdquo;.
</PARA>

<PARA>
All functions return a value of the type <type>Cyg_ErrNo</type>. If an
error condition is detected, this value will be negative and the
absolute value indicates the actual error, as specified in
<filename>cyg/error/codes.h</filename>. The only other legal return
value will be <varname>ENOERR</varname>. All other function arguments
are pointers (references). This allows the drivers to pass information
efficiently, both into and out of the driver. The most striking
example of this is the &ldquo;length&rdquo; value passed to the read
and write functions. This parameter contains the desired length of
data on input to the function and the actual transferred length on
return.
</PARA>

<PROGRAMLISTING>
// Lookup a device and return its handle 
  Cyg_ErrNo <FUNCTION><!-- <index></index> -->cyg_io_lookup</function>( 
    const char <parameter>*name</parameter>,
    cyg_io_handle_t <parameter>*handle</parameter> )
</PROGRAMLISTING>

<PARA>
This function maps a device name onto an appropriate handle. If the
named device is not in the system, then the error
<varname>-ENOENT</varname> is returned. If the device is found, then
the handle for the device is returned by way of the handle pointer
<parameter>*handle</parameter>.
</PARA>

<PROGRAMLISTING>
// Write data to a device 
Cyg_ErrNo <FUNCTION><!-- <index></index> -->cyg_io_write</function>( 
    cyg_io_handle_t <parameter>handle</parameter>,
    const void <parameter>*buf</parameter>,
    cyg_uint32 <parameter>*len</parameter> )
</PROGRAMLISTING>

<PARA>
This function sends data to a device. The size of data to send is
contained in <parameter>*len</parameter> and the actual size sent will
be returned in the same place.
</PARA>

<PROGRAMLISTING>
// Read data from a device 
Cyg_ErrNo <!-- <index></index> --><function>cyg_io_read</function>( 
    cyg_io_handle_t <parameter>handle</parameter>,
    void <parameter>*buf</parameter>,
    cyg_uint32 <parameter>*len</parameter> )
</PROGRAMLISTING>

<PARA>
This function receives data from a device. The desired size of data to
receive is contained in <parameter>*len</parameter> and the actual
size obtained will be returned in the same place.
</PARA>

<PROGRAMLISTING>
// Get the configuration of a device 
Cyg_ErrNo <FUNCTION><!-- <index></index> -->cyg_io_get_config</FUNCTION>( 
    cyg_io_handle_t <parameter>handle</parameter>,
    cyg_uint32 <parameter>key</parameter>,
    void *<parameter>buf</parameter>,
    cyg_uint32 *<parameter>len</parameter> )
</PROGRAMLISTING>

<PARA>
This function is used to obtain run-time configuration about a
device. The type of information retrieved is specified by the
<parameter>key</parameter>. The data will be returned in the given
buffer. The value of <parameter>*len</parameter> should contain the
amount of data requested, which must be at least as large as the size
appropriate to the selected key. The actual size of data retrieved is
placed in <parameter> *len</parameter>. The appropriate key values
differ for each driver and are all listed in the file
<filename>&lt;cyg/io/config_keys.h&gt;</filename>.
</PARA>

<PROGRAMLISTING>
// Change the configuration of a device 
Cyg_ErrNo <!-- <index></index> --><function>cyg_io_set_config</function>( 
    cyg_io_handle_t <parameter>handle</parameter>,
    cyg_uint32 <parameter>key</parameter>,
    const void <parameter>*buf</parameter>,
    cyg_uint32 <parameter>*len</parameter> )
</PROGRAMLISTING>

<PARA>
This function is used to manipulate or change the run-time
configuration of a device. The type of information is specified by the
<parameter>key</parameter>. The data will be obtained from the given
buffer. The value of <parameter>*len</parameter> should contain the
amount of data provided, which must match the size appropriate to the
selected key.  The appropriate key values differ for each driver and
are all listed in the file
<filename>&lt;cyg/io/config_keys.h&gt;</filename>.
</PARA>

</CHAPTER>

<!-- }}} -->
<!-- {{{ Serial Drivers  -->

<CHAPTER id="io-serial-driver-details">
<TITLE>Serial driver details</TITLE>

<PARA>
Two different classes of serial drivers are provided as a standard
part of the eCos system. These are described as &ldquo;raw
serial&rdquo; (serial) and &ldquo;tty-like&rdquo; (tty).
</PARA>

<!-- {{{ Raw Serial Drivers -->

<SECTION id="io-simple-serial-driver">
<TITLE>Raw Serial Driver</TITLE>

<PARA>
Use the include file <FILENAME>&lt;cyg/io/serialio.h&gt;</FILENAME> for
this driver.
</PARA>

<PARA>
The <!-- <index></index> -->raw serial driver is capable of sending
and receiving blocks of raw data to a serial device. Controls are
provided to configure the actual hardware, but there is no manipulation
of the data by this driver.
</PARA>

<PARA>
There may be many instances of this driver in a given system,
one for each serial channel. Each channel corresponds to a physical
device and there will typically be a device module created for this
purpose. The device modules themselves are configurable, allowing
specification of the actual hardware details, as well as such details
as whether the channel should be buffered by the serial driver,
etc.
</PARA>

<!-- {{{ Runtime Configuration -->

<SECTION>
<TITLE>Runtime Configuration</TITLE>

<para>
Runtime configuration is achieved by exchanging data structures with
the driver via the <function>cyg_io_set_config()</function> and
<function>cyg_io_get_config()</function> functions.
</para>

<PROGRAMLISTING>
typedef struct {
 cyg_serial_baud_rate_t baud;
 cyg_serial_stop_bits_t stop;
 cyg_serial_parity_t parity;
 cyg_serial_word_length_t word_length;
 cyg_uint32 flags;
} cyg_serial_info_t;
</PROGRAMLISTING>

<PARA>
The field <structfield><!-- <index></index>
-->word_length</structfield> contains the number of data bits per word
(character). This must be one of the values:
</PARA>

<PROGRAMLISTING>
 CYGNUM_SERIAL_WORD_LENGTH_5
 CYGNUM_SERIAL_WORD_LENGTH_6
 CYGNUM_SERIAL_WORD_LENGTH_7
 CYGNUM_SERIAL_WORD_LENGTH_8
</PROGRAMLISTING>

<PARA>
The field <structfield><!-- <index></index>
-->baud</structfield> contains a baud rate selection.  This must be
one of the values:
</PARA>

<PROGRAMLISTING>
 CYGNUM_SERIAL_BAUD_50
 CYGNUM_SERIAL_BAUD_75
 CYGNUM_SERIAL_BAUD_110
 CYGNUM_SERIAL_BAUD_134_5
 CYGNUM_SERIAL_BAUD_150
 CYGNUM_SERIAL_BAUD_200
 CYGNUM_SERIAL_BAUD_300
 CYGNUM_SERIAL_BAUD_600
 CYGNUM_SERIAL_BAUD_1200
 CYGNUM_SERIAL_BAUD_1800
 CYGNUM_SERIAL_BAUD_2400
 CYGNUM_SERIAL_BAUD_3600
 CYGNUM_SERIAL_BAUD_4800
 CYGNUM_SERIAL_BAUD_7200
 CYGNUM_SERIAL_BAUD_9600
 CYGNUM_SERIAL_BAUD_14400
 CYGNUM_SERIAL_BAUD_19200
 CYGNUM_SERIAL_BAUD_38400
 CYGNUM_SERIAL_BAUD_57600
 CYGNUM_SERIAL_BAUD_115200
 CYGNUM_SERIAL_BAUD_234000
</PROGRAMLISTING>

<PARA>The field <structfield><!-- <index></index>
-->stop</structfield> contains the number of stop bits. This must be
one of the values:</PARA>

<PROGRAMLISTING>
 CYGNUM_SERIAL_STOP_1
 CYGNUM_SERIAL_STOP_1_5
 CYGNUM_SERIAL_STOP_2
</PROGRAMLISTING>

<NOTE>
<title>Note</title>
<PARA>
On most hardware, a selection of 1.5 stop bits is only valid
if the word (character) length is 5.
</PARA>
</NOTE>

<PARA>The field <structfield><!-- <index></index>
-->parity</structfield> contains the parity mode.  This must be one of
the values: </PARA>

<PROGRAMLISTING>
 CYGNUM_SERIAL_PARITY_NONE
 CYGNUM_SERIAL_PARITY_EVEN
 CYGNUM_SERIAL_PARITY_ODD
 CYGNUM_SERIAL_PARITY_MARK
 CYGNUM_SERIAL_PARITY_SPACE
</PROGRAMLISTING>

<PARA>The field <structfield><!-- <index></index>
-->flags</structfield> is a bitmask which controls the behavior of the
serial device driver. It should be built from the values
<literal>CYG_SERIAL_FLAGS_xxx</literal> defined below:
</PARA>

<PROGRAMLISTING>
#define CYG_SERIAL_FLAGS_RTSCTS 0x0001
</PROGRAMLISTING>

<PARA>If this bit is set then the port is placed in &ldquo;hardware
handshake&rdquo; mode. In this mode, the CTS and RTS pins control
when data is allowed to be sent/received at the port. This
bit is ignored if the hardware does not support this level of
handshake.
</PARA>

<PROGRAMLISTING>
typedef struct {
  cyg_int32 rx_bufsize;
  cyg_int32 rx_count;
  cyg_int32 tx_bufsize;
  cyg_int32 tx_count;
} cyg_serial_buf_info_t;     
</PROGRAMLISTING>

<PARA>The field <structfield>rx_bufsize</structfield> contains
the total size of the incoming data buffer. This is set to zero on
devices that do not support buffering (i.e. polled devices).</PARA>

<PARA>The field <structfield>rx_count</structfield> contains the
number of bytes currently occupied in the incoming data buffer.
This is set to zero on devices that do not support buffering (i.e. polled
devices).</PARA>

<PARA>The field <structfield>tx_bufsize</structfield> contains the
total size of the transmit data buffer. This is set to zero on devices
that do not support buffering (i.e. polled devices).</PARA>

<PARA>The field <structfield>tx_count</structfield> contains the
number of bytes currently occupied in the transmit data buffer.  This
is set to zero on devices that do not support buffering (i.e. polled
devices).</PARA>

</SECTION>

<!-- }}} -->
<!-- {{{ API Details -->

<SECTION>
<TITLE><!-- <index></index> -->API Details</TITLE>

<!-- {{{ cyg_io_write -->

<section id="io-serial-cyg-io-write">
<title>cyg_io_write</title>

<PROGRAMLISTING>
cyg_io_write(handle, buf, len)
</PROGRAMLISTING>

<PARA>
Send the data from <parameter>buf</parameter> to the device. The
driver maintains a buffer to hold the data. The size of the
intermediate buffer is configurable within the interface module. The
data is not modified at all while it is being buffered. On return,
<parameter>*len</parameter> contains the amount of characters actually
consumed .</PARA>

<PARA>
It is possible to configure the write call to be blocking
(default) or non-blocking. Non-blocking mode requires both the configuration
option <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal>
to be enabled, and the specific device to be set to non-blocking
mode for writes (see <function>cyg_io_set_config()</function>).
</para>

<para>
In blocking mode, the call will not return until there is space in the
buffer and the entire contents of <parameter>buf</parameter> have been
consumed.
</PARA>

<PARA>
In non-blocking mode, as much as possible gets consumed from
<parameter>buf</parameter>. If everything was consumed, the call
returns <literal>ENOERR</literal>. If only part of the
<parameter>buf</parameter> contents was consumed,
<literal>-EAGAIN</literal> is returned and the caller must try
again. On return, <parameter>*len</parameter> contains the number of characters actually
consumed .</PARA>

<PARA>
The call can also return <literal>-EINTR</literal> if interrupted
via the <function>cyg_io_get_config()</function>/<literal>ABORT</literal> key.
</para>

</section>

<!-- }}} -->
<!-- {{{ cyg_io_read -->

<section id="io-serial-cyg-io-read">
<title>cyg_io_read</title>

<programlisting>
cyg_io_read(handle, buf, len)
</programlisting>

<PARA>
Receive data into the buffer, <parameter>buf</parameter>, from the
device. No manipulation of the data is performed before being
transferred.  An interrupt driven interface module will support data
arriving when no read is pending by buffering the data in the serial
driver.  Again, this buffering is completely configurable. On return,
<parameter>*len</parameter> contains the number of characters actually
received.</PARA>

<PARA>
It is possible to configure the read call to be blocking (default)
or  non-blocking. Non-blocking mode requires both the configuration
option  <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal>
to be enabled, and the specific device to be set to non-blocking
mode for reads (see <function>cyg_io_set_config()</function>).
</PARA>

<PARA>
In blocking mode, the call will not return until the requested
amount of data has been read.</PARA>

<PARA>
In non-blocking mode, data waiting in the device buffer is copied to
<parameter>buf</parameter>, and the call returns immediately. If there
was enough data in the buffer to fulfill the request,
<literal>ENOERR</literal> is returned.  If only part of the request
could be fulfilled, <literal>-EAGAIN</literal> is returned and the
caller must try again. On return, <parameter>*len</parameter> contains
the number of characters actually received.</PARA>

<PARA>
The call can also return <literal>-EINTR</literal> if interrupted via
the <function>cyg_io_get_config()</function>/<literal>ABORT</literal>
key.
</PARA>

</section>

<!-- }}} -->
<!-- {{{ cyg_io_get_config -->

<section id="io-serial-cyg-get-config">
<title>cyg_io_get_config</title>

<PROGRAMLISTING>
cyg_io_get_config(handle, key, buf, len)
</PROGRAMLISTING>

<PARA>This function returns current [runtime] information
about the device and/or driver. </PARA>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_INFO</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>cyg_serial_info_t</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>
              This function retrieves the current state of the driver
              and hardware. This information contains fields for
              hardware baud rate, number of stop bits, and parity
              mode. It also includes a set of flags that control the
              port, such as hardware flow control.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_BUFFER_INFO</literal></TERM>
    <LISTITEM>
       <variablelist>
         <VARLISTENTRY>
           <TERM>Buf type:</TERM>
           <LISTITEM>
             <PARA>cyg_serial_buf_info_t</PARA>
           </LISTITEM>
         </VARLISTENTRY>
         <VARLISTENTRY>
           <TERM>Function:</TERM>
           <LISTITEM>
             <PARA>
               This function retrieves the current state of the
               software buffers in the serial drivers. For both
               receive and transmit buffers it returns the total
               buffer size and the current number of bytes occupied in
               the buffer. It does not take into account any buffering
               such as FIFOs or holding registers that the serial
               device itself may have.
             </PARA>
           </LISTITEM>
         </VARLISTENTRY>
       </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_OUTPUT_DRAIN</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>void *</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>
              This function waits for any buffered output to
              complete. This function only completes when there is no
              more data remaining to be sent to the device.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_OUTPUT_FLUSH</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>void *</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>
              This function discards any buffered output for the
	      device.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_INPUT_DRAIN</literal></term>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>void *</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function: 	</TERM>
          <LISTITEM>
            <PARA>This function discards any buffered input for the
            device.</PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_ABORT</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA> void*</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function will cause any pending read or write calls on
            this device to return with <literal>-EABORT</literal>.</PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_READ_BLOCKING</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA> cyg_uint32 (values 0 or 1)</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function will read back the blocking-mode
            setting for read calls on this device. This call is only
            available if the configuration option
            <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal> is
            enabled.</PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_SERIAL_WRITE_BLOCKING</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA> cyg_uint32 (values 0 or 1)</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>
            This function will read back the blocking-mode
            setting for write calls on this device. This call is only
            available if the configuration option
            <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal> is enabled.</PARA>
          </listitem>
        </varlistentry>
      </variablelist>
    </listitem>
  </varlistentry>
</variablelist>

</section>

<!-- }}} -->
<!-- {{{ cyg_io_set_config -->

<section id="io-serial-cyg-set-config">
<title>cyg_io_set_config</title>

<PROGRAMLISTING>
cyg_io_set_config(handle, key, buf,len)
</PROGRAMLISTING>

<PARA>This function is used to update or change runtime configuration
of a port. </PARA>

<variablelist>
  <VARLISTENTRY>
    <TERM><literal>CYG_IO_SET_CONFIG_SERIAL_INFO</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>cyg_serial_info_t</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function updates the information for the driver
            and hardware.  The information contains fields for
            hardware baud rate, number of stop bits, and parity
            mode. It also includes a set of flags that control the
            port, such as hardware flow control.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_SET_CONFIG_SERIAL_READ_BLOCKING</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA> cyg_uint32 (values 0 or 1)</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function will set the blocking-mode for read
            calls on this device. This call is only available if the
            configuration option <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal>
            is enabled.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM><literal>CYG_IO_SET_CONFIG_SERIAL_WRITE_BLOCKING</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>cyg_uint32 (values 0 or 1)</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function will set the blocking-mode for write
            calls on this device. This call is only available if the
            configuration option <literal>CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING</literal>
            is enabled.
            </PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</section>

<!-- }}} -->

</SECTION>

<!-- }}} -->

</SECTION>

<!-- }}} -->
<!-- {{{ TTY Drivers -->

<SECTION id="io-tty-driver">
<TITLE> TTY driver</TITLE>

<PARA>
Use the include file <filename>&lt;cyg/io/ttyio.h&gt;</filename> for
this driver.
</PARA>

<PARA>
This <!-- <index></index> -->driver is built on top of the simple
serial driver and is typically used for a device that interfaces with
humans such as a terminal. It provides some minimal formatting of data
on output and allows for line-oriented editing on input.
</PARA>

<!-- {{{ Runtime Configuration -->

<SECTION>
<TITLE>Runtime configuration</TITLE>

<para>
Runtime configuration is achieved by exchanging data structures with
the driver via the <function>cyg_io_set_config()</function> and
<function>cyg_io_get_config()</function> functions.
</para>


<PROGRAMLISTING>
typedef struct {
 cyg_uint32 tty_out_flags;
 cyg_uint32 tty_in_flags;
} cyg_tty_info_t;
</PROGRAMLISTING>

<PARA>The field <structfield><!-- <index></index> -->tty_out_flags</structfield>
is used to control what happens to data as it is send to the serial
port. It contains a bitmap comprised of the bits as defined by the
<literal>CYG_TTY_OUT_FLAGS_xxx</literal> values below. </PARA>

<PROGRAMLISTING>
#define CYG_TTY_OUT_FLAGS_CRLF 0x0001 // Map '\n' =&gt; '\r\n' on output
</PROGRAMLISTING>

<PARA>If this bit is set in <structfield>tty_out_flags</structfield>,
any occurrence of the character &quot;\n&quot; will
be replaced by the sequence &quot;\r\n&quot; before
being sent to the device.</PARA>

<PARA>The field <structfield><!-- <index></index> -->tty_in_flags</structfield>
is used to control how data is handled as it comes from the serial
port. It contains a bitmap comprised of the bits as defined by the
<literal>CYG_TTY_IN_FLAGS_xxx</literal> values below. </PARA>

<PROGRAMLISTING>
#define CYG_TTY_IN_FLAGS_CR 0x0001 // Map '\r' =&gt; '\n' on input
</PROGRAMLISTING>

<PARA>If this bit is set in <structfield>tty_in_flags</structfield>, the
character &quot;\r&quot; (&ldquo;return&rdquo; or &ldquo;enter&rdquo; on
most keyboards) will be mapped to &quot;\n&quot;.</PARA>

<PROGRAMLISTING>
#define CYG_TTY_IN_FLAGS_CRLF 0x0002 // Map '\r\n' =&gt; '\n' on input
</PROGRAMLISTING>

<PARA>
If this bit is set in <structfield>tty_in_flags</structfield>, the
character sequence &quot;\r\n&quot; (often sent by DOS/Windows
based terminals) will be mapped to &quot;\n&quot;. </PARA>

<PROGRAMLISTING>
#define CYG_TTY_IN_FLAGS_ECHO 0x0004 // Echo characters as processed
</PROGRAMLISTING>

<PARA>
If this bit is set in <structfield>tty_in_flags</structfield>, characters
will be echoed back to the serial port as they are processed. </PARA>

<PROGRAMLISTING>
#define CYG_TTY_IN_FLAGS_BINARY 0x0008 // No input processing
</PROGRAMLISTING>

<PARA>If this bit is set in <structfield>tty_in_flags</structfield>, the
input will not be manipulated in any way before being placed in
the user&rsquo;s buffer. </PARA>

</SECTION>

<!-- }}} -->
<!-- {{{ API Details -->

<SECTION>
<TITLE><!-- <index></index> -->API details</TITLE>

<PROGRAMLISTING>
cyg_io_read(handle, buf, len)
</PROGRAMLISTING>

<PARA>This function is used to read data from the device. In the
default case, data is read until an end-of-line character ("\n"
or "\r") is read. Additionally, the characters are echoed
back to the [terminal] device. Minimal editing
of the input is also supported. </PARA>

<NOTE>
<PARA>When connecting to a remote target via GDB it is not possible
to provide console input while GDB is connected. The GDB remote
protocol does not support input. Users must disconnect from GDB
if this functionality is required.</PARA>
</NOTE>

<PROGRAMLISTING>	
cyg_io_write(handle, buf, len)
</PROGRAMLISTING>

<PARA>This function is used to send data to the device. In the default
case, the end-of-line character "\n" is replaced by the
sequence "\r\n". </PARA>

<PROGRAMLISTING>
cyg_io_get_config(handle, key, buf, len)
</PROGRAMLISTING>

<PARA>This function is used to get information about the channel&rsquo;s
configuration at runtime. </PARA>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM><literal>CYG_IO_GET_CONFIG_TTY_INFO</literal></TERM>
    <LISTITEM>
      <variablelist>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>cyg_tty_info_t</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function:</TERM>
          <LISTITEM>
            <PARA>This function retrieves the current state of the
	    driver.
            </PARA>
          </listitem>
        </varlistentry>
      </variablelist>
    </listitem>
  </varlistentry>
</variablelist>

<PARA>Serial driver keys (see above) may also be specified
in which case the call is passed directly to the serial
driver. </PARA>

<PROGRAMLISTING>
cyg_io_set_config(handle, key, buf, len)
</PROGRAMLISTING>

<PARA>This function is used to modify the channel&rsquo;s configuration
at runtime. </PARA>


<VARIABLELIST>
  <VARLISTENTRY>
    <TERM><literal>CYG_IO_SET_CONFIG_TTY_INFO</literal></term>
    <LISTITEM>
      <VARIABLELIST>
        <VARLISTENTRY>
          <TERM>Buf type:</TERM>
          <LISTITEM>
            <PARA>cyg_tty_info_t</PARA>
          </LISTITEM>
        </VARLISTENTRY>
        <VARLISTENTRY>
          <TERM>Function: 	</TERM>
          <LISTITEM>
            <PARA>This function changes the current state of the
	    driver.</PARA>
          </LISTITEM>
        </VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

<PARA>Serial driver
keys (see above) may also be specified in which case the
call is passed directly to the serial driver. </PARA>

</SECTION>

<!-- }}} -->

</SECTION>

<!-- }}} -->
<!-- {{{ DSP Driver -->


<!-- }}} -->

</CHAPTER>

<!-- }}} -->
<!-- {{{ How to Write a Driver -->

<CHAPTER id="io-how-to-write-a-driver">
<TITLE>How to Write a Driver</TITLE>

<!-- {{{ Intro -->

<PARA>
A <!-- <index></index> -->device driver is nothing more than a
named entity that supports the basic I/O functions - read, write, get
config, and set config. Typically a device driver also uses and
manages interrupts from the device. While the interface is generic and
device driver independent, the actual driver implementation is
completely up to the device driver designer. </PARA>

<PARA>That said, the reason for using a device driver is to provide
access to a device from application code in as general purpose a
fashion as reasonable. Most driver writers are also concerned with
making this access as simple as possible while being as efficient
as possible. </PARA>

<PARA>Most device drivers are concerned with the movement of information,
for example data bytes along a serial interface, or packets in a
network. In order to make the most efficient use of system resources,
interrupts are used. This will allow other application processing
to take place while the data transfers are under way, with interrupts
used to indicate when various events have occurred. For example,
a serial port typically generates an interrupt after a character
has been sent &ldquo;down the wire&rdquo; and the interface
is ready for another. It makes sense to allow further application
processing while the data is being sent since this can take quite
a long time. The interrupt can be used to allow the driver to send
a character as soon as the current one is complete, without any
active participation by the application code. </PARA>

<PARA>The main building blocks for device drivers are found in the
include file: <filename>&lt;cyg/io/devtab.h&gt;</filename></PARA>

<PARA>All device drivers in <EMPHASIS>eCos</EMPHASIS> are described
by a device table entry, using the <type>cyg_devtab_entry_t</type> type.
The entry should be created using the <FUNCTION>DEVTAB_ENTRY()</FUNCTION> macro,
like this:</PARA>

<PROGRAMLISTING><function>
DEVTAB_ENTRY</function>(l, name, dep_name, handlers, init, lookup, priv)
</PROGRAMLISTING>

<variablelist>
<title>Arguments</title>
  <varlistentry>
    <term><parameter>l</parameter></term>
    <listitem><para>The "C" label for this device table entry.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>name</parameter></term>
    <listitem><para>The "C" string name for the device.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>dep_name</parameter></term>
    <listitem><para>For a layered device, the "C" string name of the
    device this device is built upon.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>handlers</parameter></term>
    <listitem><para>A pointer to the I/O function "handlers" (see below).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>init</parameter></term>
    <listitem><para>A function called when eCos is initialized. This
    function can query the device, setup hardware, etc.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>lookup</parameter></term>
    <listitem><para>A function called when <function>cyg_io_lookup()</function> is called
    for this device. </para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>priv</parameter></term>
    <listitem><para>A placeholder for any device specific data
    required by the driver.</para></listitem>
  </varlistentry>
</variablelist>

<PARA>The interface to the driver is through the <structfield><!--
<index></index> -->handlers</structfield> field.  This is a pointer to
a set of functions which implement the various <function>cyg_io_XXX()</function>
routines. This table is defined by the macro:</PARA>


<PROGRAMLISTING>
DEVIO_TABLE(l, write, read, select, get_config, set_config)
</PROGRAMLISTING>

<variablelist>
<title>Arguments</title>
  <varlistentry>
    <term><parameter>l</parameter></term>
    <listitem><para>The "C" label for this table of handlers.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term>write</term>
    <listitem><para>The function called as a result of
    <function>cyg_io_write()</function>.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term>read</term>
    <listitem><para>The function called as a result of
    <function>cyg_io_read()</function>. </para></listitem>
  </varlistentry>
  <varlistentry>
    <term>select</term>
    <listitem><para>The function called as a result of
    <function>cyg_io_select()</function>. </para></listitem>
  </varlistentry>
  <varlistentry>
    <term>get_config</term>
    <listitem><para>The function called as a result of
    <function>cyg_io_get_config()</function>.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term>set_config</term>
    <listitem><para>The function called as a result of
    <function>cyg_io_set_config()</function>. </para></listitem>
  </varlistentry>
</variablelist>

<PARA>
When <EMPHASIS>eCos</EMPHASIS> is initialized (sometimes called
&ldquo;boot&rdquo; time), the <function>init()</function> function is called
for all devices in the system. The <function>init()</function> function is
allowed to return an error in which case the device will be placed
&ldquo;off line&rdquo; and all I/O requests to that device will be
considered in error.
</PARA>

<PARA>
The <function>lookup()</function> function is called whenever
the <FUNCTION>cyg_io_lookup()</FUNCTION> function
is called with this device name. The lookup function may cause the device
to come &ldquo;on line&rdquo; which would then allow I/O
operations to proceed. Future versions of the I/O system
will allow for other states, including power saving modes,
etc.
</PARA>

<!-- }}} -->
<!-- {{{ How to Write a Serial Hardware Interface Driver -->

<SECTION id="io-how-to-write-serial-interface-driver">
<TITLE>How to Write a Serial Hardware Interface Driver</TITLE>


<PARA>The standard serial driver supplied with
<EMPHASIS>eCos</EMPHASIS> is structured as a hardware independent
portion and a hardware dependent interface module. To add support for
a new serial port, the user should be able to use the existing
hardware independent portion and just add their own <!--
<index></index> -->interface driver which handles the details of the
actual device. The user should have no need to change the hardware
independent portion. </PARA>

<PARA>The interfaces used by the serial driver and serial implementation
modules are contained in the file <filename>&lt;cyg/io/serial.h&gt;</filename>
</PARA>

<NOTE>
<PARA>In the sections below we use the notation &lt;&lt;xx&gt;&gt; to
mean a module specific value, referred to as &ldquo;xx&rdquo; below.</PARA>
</NOTE>

<!-- {{{ DevTab Entry -->

<section>
<title>DevTab Entry</title>

<PARA>The interface module contains the devtab entry (or entries
if a single module supports more than one interface). This entry
should have the form: </PARA>

<PROGRAMLISTING>
DEVTAB_ENTRY(&lt;&lt;module_name&gt;&gt;, 
             &lt;&lt;device_name&gt;&gt;,
             0,
             &amp;serial_devio, 
             &lt;&lt;module_init&gt;&gt;, 
             &lt;&lt;module_lookup&gt;&gt;,
             &amp;&lt;&lt;serial_channel&gt;&gt;
            );
</PROGRAMLISTING>

<variablelist>
<title>Arguments</title>
  <varlistentry>
    <term><parameter>module_name</parameter></term>
    <listitem><para>The "C" label for this devtab entry</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>device_name</parameter></term>
    <listitem><para>The "C" string for the
    device. E.g. <filename>/dev/serial0</filename>.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>serial_devio</parameter></term>
    <listitem><para>The table of I/O functions. This set is defined in
    the hardware independent serial driver and should be used.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>module_init</parameter></term>
    <listitem><para>The module initialization function.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>module_lookup</parameter></term>
    <listitem><para>The device lookup function. This function
    typically sets up the device for actual use, turning on
    interrupts, configuring the port, etc.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>serial_channel</parameter></term>
    <listitem><para>This table (defined below) contains the interface
    between the interface module and the serial driver proper.</para></listitem>
  </varlistentry>
</variablelist>

</section>

<!-- }}} -->
<!-- {{{ Serial Channel Structure -->

<section>
<title>Serial Channel Structure</title>

<PARA>Each serial device must have a &ldquo;serial channel&rdquo;.
This is a set of data which describes all operations on the device.
It also contains buffers, etc., if the device is to be buffered.
The serial channel is created by the macro: </PARA>

<PROGRAMLISTING>
SERIAL_CHANNEL_USING_INTERRUPTS(l, funs, dev_priv, baud,stop, parity, word_length,
                                flags, out_buf, out_buflen, in_buf, in_buflen)
</PROGRAMLISTING>

<variablelist>
  <title>Arguments</title>
  <varlistentry>
    <term><parameter>l</parameter></term>
    <listitem><para>The "C" label for this structure.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>funs</parameter></term>
    <listitem><para>The set of interface functions (see below).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>dev_priv</structfield></term>
    <listitem><para>A placeholder for any device specific data for
    this channel.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>baud</structfield></term>
    <listitem><para>The initial baud rate value
    (<type>cyg_serial_baud_t</type>).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>stop</structfield></term>
    <listitem><para>The initial stop bits value
    (<type>cyg_serial_stop_bits_t</type>).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>parity</structfield></term>
    <listitem><para>The initial parity mode value
    (<type>cyg_serial_parity_t</type>).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>word_length</structfield></term>
    <listitem><para>The initial word length value
    (<type>cyg_serial_word_length_t</type>).</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>flags</structfield></term>
    <listitem><para>The initial driver flags value.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>out_buf</structfield></term>
    <listitem><para>Pointer to the output
    buffer. <literal>NULL</literal> if none required.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>out_buflen</structfield></term>
    <listitem><para>The length of the output buffer.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>in_buf</structfield></term>
    <listitem><para>pointer to the input
    buffer. <literal>NULL</literal> if none required.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>in_buflen</structfield></term>
    <listitem><para>The length of the input buffer. </PARA></listitem>
  </varlistentry>
</variablelist>

<PARA>
If either buffer length is zero, no buffering will take place
in that direction and only polled mode functions will be used.
</PARA>

<PARA>
The interface from the hardware independent driver into the
hardware interface module is contained in the <structfield>funs</structfield> table.
This is defined by the macro:
</PARA>

</section>

<!-- }}} -->
<!-- {{{ Serial Functions Structure -->

<section>
<title>Serial Functions Structure</title>

<PROGRAMLISTING>
SERIAL_FUNS(l, putc, getc, set_config, start_xmit, stop_xmit)
</PROGRAMLISTING>


<variablelist>
  <title>Arguments</title>
  <varlistentry>
    <term><structfield>l</structfield></term>
    <listitem><para>The "C" label for this structure.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>putc</structfield></term>
    <listitem>
      <para><literal>bool (*putc)(serial_channel *priv, unsigned char
      c)</literal></para>
      <para>
      This function sends one character to the interface. It should
      return <literal>true</literal> if the character is actually consumed. It should
      return <literal>false</literal> if there is no space in the interface
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>getc</structfield></term>
    <listitem>
      <para><literal>unsigned char (*getc)(serial_channel *priv)</literal></para>
      <para>
      This function fetches one character from the interface. It will
      be only called in a non-interrupt driven mode, thus it should
      wait for a character by polling the device until ready.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><structfield>set_config</structfield></term>
    <listitem>
      <para><literal>bool (*set_config)(serial_channel
      *priv,cyg_serial_info_t *config)</literal></para>
      <para>
        This function is used to configure the port. It should return
        <literal>true</literal> if the hardware is updated to match the desired
        configuration. It should return <literal>false</literal> if the port cannot
        support some parameter specified by the given
        configuration. E.g. selecting 1.5 stop bits and 8 data bits is
        invalid for most serial devices and should not be allowed.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>start_xmit</parameter></term>
    <listitem><para><literal>void (*start_xmit)(serial_channel *priv)</literal></para>
      <para>
        In interrupt mode, turn on the transmitter and allow for
        transmit interrupts.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><parameter>stop_xmit</parameter></term>
    <listitem>
      <para><literal>void (*stop_xmit)(serial_channel *priv)</literal></para>
      <para>In interrupt mode, turn off the transmitter.</PARA>
    </listitem>
  </varlistentry>
</variablelist>

</section>

<!-- }}} -->
<!-- {{{ Callbacks -->

<section>
<title>Callbacks</title>

<PARA>
The device interface module can execute functions in the
hardware independent driver via <literal>chan-&gt;callbacks</literal>.
These functions are available:
</PARA>

<PROGRAMLISTING>
void (*serial_init)( serial_channel *chan )
</PROGRAMLISTING>

<PARA>This function is used to initialize the serial channel. It
is only required if the channel is being used in interrupt
mode.</PARA>

<PROGRAMLISTING>
void (*xmt_char)( serial_channel *chan )
</PROGRAMLISTING>

<PARA>
This function would be called from an interrupt handler after a
transmit interrupt indicating that additional characters may be
sent. The upper driver will call the <function>putc</function>
function as appropriate to send more data to the device.</PARA>

<PROGRAMLISTING>
void (*rcv_char)( serial_channel *chan, unsigned char c )
</PROGRAMLISTING>


<PARA>
This function is used to tell the driver that a character has arrived
at the interface. This function is typically called from the interrupt
handler. </PARA>

<PARA>
Furthermore, if the device has a FIFO it should require the hardware
independent driver to provide block transfer functionality (driver CDL
should include &quot;implements
CYGINT_IO_SERIAL_BLOCK_TRANSFER&quot;).  In that case, the following
functions are available as well:</PARA>

<PROGRAMLISTING>
xmt_req_reply_t (*data_xmt_req)(serial_channel *chan,
                     int space,
                     int* chars_avail,
                     unsigned char** chars)
void (*data_xmt_done)(serial_channel *chan, int chars_sent)
</PROGRAMLISTING>

<PARA>
Instead of calling <function>xmt_char()</function> to get a single
character for transmission at a time, the driver should call
<function>data_xmt_req()</function> in a loop, requesting character
blocks for transfer. Call with a <parameter>space</parameter> argument of how much space
there is available in the FIFO.</PARA>

<PARA>If the call returns <literal>true</literal>, the driver can read
<parameter>chars_avail</parameter> characters from
<parameter>chars</parameter> and copy them into the FIFO.</PARA>

<PARA>If the call returns <literal>false</literal>, there are
no more buffered characters and the driver should continue without
filling up the FIFO.</PARA>

<PARA>When all data has been unloaded, the
driver must call <function>data_xmt_done()</function>.</PARA>


<PROGRAMLISTING>
rcv_req_reply_t (*data_rcv_req)(serial_channel *chan,
                     int avail,
                     int* space_avail,
                     unsigned char** space)
void (*data_rcv_done)(serial_channel *chan, int chars_rcvd)
</PROGRAMLISTING>

<PARA>Instead of calling <function>rcv_char()</function> with a single
character at a time, the driver should call
<function>data_rcv_req()</function> in a loop, requesting space to
unload the FIFO to. <parameter>avail</parameter> is the number of
characters the driver wishes to unload.</PARA>


<PARA>If the call returns <literal>true</literal>, the driver can copy
<parameter>space_avail</parameter> characters to
<parameter>space</parameter>. </PARA>


<PARA>If the call returns <literal>false</literal>, the input buffer is
full. It is up to the driver to decide what to do in that case
(callback functions for registering overflow are being planned for
later versions of the serial driver).
</PARA>

<PARA>When all data has been unloaded, the driver must call
<function>data_rcv_done()</function>.</PARA>

</section>

<!-- }}} -->

</SECTION>

<!-- }}} -->
<!-- {{{ Serial Testing -->

<section id="io-serial-testing-with-serfilter">
<title>Serial testing with ser_filter</title>

<!-- {{{ Rationale -->

<section id="io-serfilter-rationale">
<title>Rationale</title>

<para>
Since some targets only have one serial connection, a serial testing harness
needs to be able to share the connection with <application>GDB</application>
(however, the test and <application>GDB</application> can also run on separate
lines).
</para>

<para>
The <firstterm>serial filter</firstterm> (<application>ser_filter</application>)
sits between the serial port and <application>GDB</application> and monitors
the exchange of data between <application>GDB</application> and the target.
Normally, no changes are made to the data.
</para>

<para>
When a test request packet is sent from the test on the target, it is 
intercepted by the filter.
</para>

<para>
The filter and target then enter a loop, exchanging protocol data between
them which <application>GDB</application> never sees.
</para>

<para>
In the event of a timeout, or a crash on the target, the filter falls
back into its pass-through mode. If this happens due to a crash it should be
possible to start regular debugging with <application>GDB</application>. The
filter will stay in the pass-though mode until <application>GDB</application>
disconnects.
</para>
</section>

<!-- }}} -->
<!-- {{{ The Protocol -->

<section id="io-serfilter-protocol">
<title>The Protocol</title>

<para>The protocol commands are prefixed with an <literal>&quot;@&quot;</literal>
character which the serial filter is looking for. The protocol
commands include:
</para>

<variablelist>
  <varlistentry>
    <term><literal>PING</literal></term>
    <listitem>
      <para>Allows the test on the target to probe for the filter. The
      filter responds with <literal>OK</literal>, while
      <application>GDB</application> would just ignore the
      command. This allows the tests to do nothing if they require the
      filter and it is not present.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><literal>CONFIG</literal></term>
    <listitem>
      <para>Requests a change of serial line configuration. Arguments
      to the command specify baud rate, data bits, stop bits, and
      parity. [This command is not fully implemented yet - there is no
      attempt made to recover if the new configuration turns out to
      cause loss of data.]</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><literal>BINARY</literal></term>
    <listitem>
      <para>Requests data to be sent from the filter to the
      target. The data is checksummed, allowing errors in the transfer
      to be detected.  Sub-options of this command control how the
      data transfer is made:</para>
      <variablelist>
        <varlistentry>
          <term><literal>NO_ECHO</literal></term>
          <listitem>
            <para>(serial driver receive test) Just send data from the
            filter to the target. The test verifies the checksum and
            PASS/FAIL depending on the result. </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><literal>EOP_ECHO</literal></term>
          <listitem>
            <para>(serial driver half-duplex receive and send test) As
            <literal>NO_ECHO</literal> but the test echoes back the
            data to the filter.  The filter does a checksum on the
            received data and sends the result to the target. The test
            PASS/FAIL depending on the result of both checksum
            verifications.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><literal>DUPLEX_ECHO</literal></term>
          <listitem>
            <para>(serial driver duplex receive and send test) Smaller
            packets of data are sent back and forth in a pattern that
            ensures that the serial driver will be both sending and
            receiving at the same time. Again, checksums are computed
            and verified resulting in PASS/FAIL.
            </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><literal>TEXT</literal></term>
    <listitem>
      <para> This is a test of the text translations in the TTY layer.
      Requests a transfer of text data from the target to the filter
      and possibly back again. The filter treats this as a binary
      transfer, while the target ma be doing translations on the
      data. The target provides the filter with checksums for what it
      should expect to see. This test is not implemented yet.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>The above commands may be extended, and new commands added, as
required to test (new) parts of the serial drivers in
<productname>eCos</productname>.
</para>

</section>

<!-- }}} -->
<!-- {{{ The Serial Tests -->

<section id="io-serfilter-serial-tests">
<title>The Serial Tests</title>

<para>
The serial tests are built as any other eCos test. After running the
<command>make tests</command> command, the tests can be found in
<filename>install/tests/io_serial/</filename></para>

<variablelist>
  <varlistentry>
    <term><filename>serial1</filename></term>
    <listitem><para>A simple API test.</para></listitem>
  </varlistentry>
  <varlistentry>
    <term><filename>serial2</filename></term>
    <listitem>
      <para>A simple serial send test. It writes out two strings, one
      raw and one encoded as a <application>GDB</application>
      O-packet</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><filename>serial3</filename> [ requires the serial filter ]</term>
    <listitem>
      <para>This tests the half-duplex send and receive capabilities
      of the serial driver. </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><filename>serial4</filename> [ requires the serial filter ]</term>
    <listitem>
      <para>This test attempts to use a few different serial
      configurations, testing the driver's configuration/setup
      functionality. </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><filename>serial5</filename> [ requires the serial filter ]</term>
    <listitem>
      <para>This tests the duplex send and receive capabilities of the
      serial driver. </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>All tests should complete in less than 30 seconds.</para>

</section>

<!-- }}} -->
<!-- {{{ Serial Filter Usage-->

<section id="io-serfilter-usage">
<title>Serial Filter Usage</title>

<para>Running the ser_filter program with no (or wrong) arguments results in
the following output:
</para>

<screen>
Usage: ser_filter [-t -S] TcpIPport SerialPort BaudRate 
or: ser_filter -n [-t -S] SerialPort BaudRate 
-t: Enable tracing. 
-S: Output data read from serial line. 
-c: Output data on console instead of via GDB. 
-n: No GDB. 
</screen>

<para>The normal way to use it with GDB is to start the filter:</para>

<screen>
$ <userinput>ser_filter -t 9000 com1 38400</userinput>
</screen>

<para>
In this case, the filter will be listening on port 9000 and connect to the
target via the serial port <literal>COM1</literal> at 38400 baud. On a UNIX
host, replace "<literal>COM1</literal>" with a device such as 
"<filename>/dev/ttyS0</filename>".
</para>

<para>
The <option>-t</option> option enables tracing which will cause the
filter to describe its actions on the console.
</para>

<para>Now start <application>GDB</application> with one of the tests as an
argument:
</para>

<screen>
$ <userinput>mips-tx39-elf-gdb -nw install/tests/io_serial/serial3</userinput>
</screen>

<para>Then connect to the filter:</para>

<screen>
(gdb) <userinput>target remote localhost:9000</userinput>
</screen>

<para>
This should result in a connection in exactly the same way as if you
had connected directly to the target on the serial line.
</para>

<screen>
(gdb) <userinput>c</userinput>
</screen>

<para>
Which should result in output similar to the below:
</para>

<screen>
Continuing. 
INFO: &lt;BINARY:16:1!&gt; 
PASS: &lt;Binary test completed&gt;
INFO: &lt;BINARY:128:1!&gt; 
PASS: &lt;Binary test completed&gt;
INFO: &lt;BINARY:256:1!&gt; 
PASS: &lt;Binary test completed&gt;
INFO: &lt;BINARY:1024:1!&gt; 
PASS: &lt;Binary test completed&gt;
INFO: &lt;BINARY:512:0!&gt;
PASS: &lt;Binary test completed&gt;
... 
PASS: &lt;Binary test completed&gt;
INFO: &lt;BINARY:16384:0!&gt;
PASS: &lt;Binary test completed&gt;
PASS: &lt;serial13 test OK&gt;
EXIT: &lt;done&gt;
</screen>

<para>
If any of the individual tests fail the testing will terminate with a 
<computeroutput>FAIL</computeroutput>.
</para>

<para>
With tracing enabled, you would also see the filter's status output:
</para>

<para>
The <literal>PING</literal> command sent from the target to determine the
presence of the filter:
</para>

<screen>
[400 11:35:16] Dispatching command PING 
[400 11:35:16] Responding with status OK
</screen>

<para>Each of the binary commands result in output similar to:</para>

<screen>
[400 11:35:16] Dispatching command BINARY 
[400 11:35:16] Binary data (Size:16, Flags:1). 
[400 11:35:16] Sending CRC: '170231!', len: 7. 
[400 11:35:16] Reading 16 bytes from target. 
[400 11:35:16] Done. in_crc 170231, out_crc 170231. 
[400 11:35:16] Responding with status OK 
[400 11:35:16] Received DONE from target.
</screen>

<para>
This tracing output is normally sent as O-packets to <application>GDB
</application> which will display the tracing text. By using the
<option>-c </option> option, the tracing text can be redirected to the
console from which ser_filter was started.
</para>

</section>

<!-- }}} -->
<!-- {{{ A Note on Failures -->

<section id="io-serfilter-failures">
<title>A Note on Failures</title>

<para>
A serial connection (especially when driven at a high baud rate) can garble the
transmitted data because of noise from the environment. It is not the job of
the serial driver to ensure data integrity - that is the job of protocols
layering on top of the serial driver. </para>

<para>In the current implementation the serial tests and the serial filter are
not resilient to such data errors. This means that the test may crash or hang
(possibly without reporting a <computeroutput>FAIL</computeroutput>). It also
means that you should be aware of random errors - a <computeroutput>FAIL
</computeroutput> is not necessarily caused by a bug in the serial driver.
</para>

<para>Ideally, the serial testing infrastructure should be able to distinguish
random errors from consistent errors - the former are most likely due to noise
in the transfer medium, while the latter are more likely to be caused by faulty
drivers. The current implementation of the infrastructure does not have this
capability.</para>

</section>

<!-- }}} -->
<!-- {{{ Debugging -->

<section id="io-serfilter-debugging">
<title>Debugging</title>

<para>If a test fails, the serial filter's output may provide some hints about
what the problem is. If the option <option>-S</option> is used when starting
the filter, data received from the target is printed out: 
</para>

<screen>
[400 11:35:16] 0000 50 41 53 53 3a 3c 42 69 'PASS:&lt;Bi'
[400 11:35:16] 0008 6e 61 72 79 20 74 65 73 'nary.tes' 
[400 11:35:16] 0010 74 20 63 6f 6d 70 6c 65 't.comple' 
[400 11:35:16] 0018 74 65 64 3e 0d 0a 49 4e 'ted&gt;..IN' 
[400 11:35:16] 0020 46 4f 3a 3c 42 49 4e 41 'FO:&lt;BINA'
[400 11:35:16] 0028 52 59 3a 31 32 38 3a 31 'RY:128:1' 
[400 11:35:16] 0030 21 3e 0d 0a 40 42 49 4e '!..@BIN' 
[400 11:35:16] 0038 41 52 59 3a 31 32 38 3a 'ARY:128:' 
[400 11:35:16] 0040 31 21 .. .. .. .. .. .. '1!' 
</screen>

<para>In the case of an error during a testing command the data received by the
filter will be printed out, as will the data that was expected. This allows
the two data sets to be compared which may give some idea of what the problem
is.</para>

</section>

<!-- }}} -->

</section>

<!-- }}} -->

</chapter>

<!-- }}} -->
<!-- {{{ Device Driver API -->

<CHAPTER id="devapi-device-driver-interface-to-the-kernel">
<TITLE>Device Driver Interface to the Kernel</TITLE>

<PARA>
This chapter describes the API that device drivers may use
to interact with the kernel and HAL. It is primarily concerned with
the control and management of interrupts and the synchronization of
ISRs, DSRs and threads.
</PARA>

<PARA>
The same API will be present in configurations where the kernel
is not present. In this case the functions will be supplied by code
acting directly on the HAL.
</PARA>


<!-- {{{ Interrupt Model -->

<SECTION id="devapi-interrupt-model">
<TITLE>Interrupt Model</TITLE>

<PARA>
<EMPHASIS>eCos</EMPHASIS> presents a three level interrupt model to
<!-- <index></index> -->device drivers. This consists of <!--
<index></index> -->Interrupt Service Routines (ISRs) that are invoked
in response to a hardware interrupt; <!-- <index></index> -->Deferred
Service Routines (DSRs) that are invoked in response to a request by
an ISR; and threads that are the clients of the driver. </PARA>

<PARA>
Hardware interrupts are delivered with minimal intervention to an
ISR. The HAL decodes the hardware source of the interrupt and calls
the ISR of the attached interrupt object. This ISR may manipulate the
hardware but is only allowed to make a restricted set of calls on the
driver API. When it returns, an ISR may request that its DSR should be
scheduled to run.
</PARA>

<PARA>
A DSR will be run when it is safe to do so without interfering with
the scheduler. Most of the time the DSR will run immediately after the
ISR, but if the current thread is in the scheduler, it will be delayed
until the thread is finished. A DSR is allowed to make a larger set of
driver API calls, including, in particular, being able to call
<FUNCTION>cyg_drv_cond_signal()</FUNCTION> to wake up waiting
threads.
</PARA>

<PARA>
Finally, threads are able to make all API calls and in particular are
allowed to wait on mutexes and condition variables. </PARA>


<PARA>
For a device driver to receive interrupts it must first define ISR and
DSR routines as shown below, and then call
<FUNCTION>cyg_drv_interrupt_create()</FUNCTION>.  Using the handle
returned, the driver must then call
<FUNCTION>cyg_drv_interrupt_attach()</FUNCTION> to actually attach the
interrupt to the hardware vector.
</PARA>


</SECTION>

<!-- }}} -->
<!-- {{{ Synchronization -->

<SECTION id="devapi-synchronization">
<TITLE><!-- <index></index> -->Synchronization</TITLE>

<PARA>There are three levels of synchronization supported:</PARA>

<ORDEREDLIST>
  <LISTITEM>
    <PARA>
    Synchronization with ISRs. This normally means disabling
    interrupts to prevent the ISR running during a critical
    section. In an SMP environment, this will also require the use of
    a spinlock to synchronize with ISRs, DSRs or threads running on
    other CPUs.  This is implemented by the
    <FUNCTION>cyg_drv_isr_lock()</FUNCTION> and
    <FUNCTION>cyg_drv_isr_unlock()</FUNCTION> functions. This
    mechanism should be used sparingly and for short periods only.
    For finer grained synchronization, individual spinlocks are also
    supplied.
    </PARA>
  </LISTITEM>

  <LISTITEM>
    <PARA>
    Synchronization with DSRs. This will be implemented in the kernel
    by taking the scheduler lock to prevent DSRs running during
    critical sections. In non-kernel configurations it will be
    implemented by non-kernel code. This is implemented by the
    <FUNCTION>cyg_drv_dsr_lock()</FUNCTION> and
    <FUNCTION>cyg_drv_dsr_unlock()</FUNCTION> functions. As with ISR
    synchronization, this mechanism should be used sparingly. Only
    DSRs and threads may use this synchronization mechanism, ISRs are
    not allowed to do this.
    </PARA>
  </LISTITEM>
  <LISTITEM>
    <PARA>
    Synchronization with threads. This is implemented with mutexes
    and condition variables. Only threads may lock the mutexes and
    wait on the condition variables, although DSRs may signal
    condition variables.
    </PARA>
  </LISTITEM>
</ORDEREDLIST>

<PARA>
Any data that is accessed from more than one level must be protected
against concurrent access. Data that is accessed by ISRs must be
protected with the ISR lock, or a spinlock at all times,
<emphasis>even in ISRs</emphasis>. Data that is shared between DSRs
and threads should be protected with the DSR lock. Data that is only
accessed by threads must be protected with mutexes.
</PARA>

</SECTION>

<!-- }}} -->
<!-- {{{ SMP Support -->

<SECTION id="devapi-smp-support">
<TITLE><!-- <index></index> -->SMP Support</TITLE>

<para>
Some eCos targets contain support for Symmetric Multi-Processing (SMP)
configurations, where more than one CPU may be present. This option
has a number of ramifications for the way in which device drivers must
be written if they are to be SMP-compatible. 
</para>

<para>
Since it is possible for the ISR, DSR and thread components of a
device driver to execute on different CPUs, it is important that
SMP-compatible device drivers use the driver API routines correctly.
</para>

<para>
Synchronization between threads and DSRs continues to require that the
thread-side code use <function>cyg_drv_dsr_lock()</function> and
<function>cyg_drv_dsr_unlock()</function> to protect access to shared
data. While it is not strictly necessary for DSR code to claim the DSR
lock, since DSRs are run with it claimed already, it is good practice
to do so.
</para>

<para>
Synchronization between ISRs and DSRs or threads requires that access
to sensitive data be protected, in all places, by calls to
<function>cyg_drv_isr_lock()</function> and
<function>cyg_drv_isr_unlock()</function>. Disabling or masking
interrupts is not adequate, since the thread or DSR may be running on
a different CPU and interrupt enable/disable only work on the current
CPU.
</para>

<para>
The ISR lock, for SMP systems, not only disables local interrupts, but
also acquires a spinlock to protect against concurrent access from
other CPUs. This is necessary because ISRs are not run with the
scheduler lock claimed. Hence they can run in parallel with the other
components of the device driver.
</para>

<para>
The ISR lock provided by the driver API is just a shared spinlock that
is available for use by all drivers. If a driver needs to implement a
finer grain of locking, it can use private spinlocks, accessed via the
<function>cyg_drv_spinlock_*()</function> functions.
</para>

</section>

<!-- }}} -->
<!-- {{{ Device Driver Models -->

<SECTION id="devapi-device-driver-models">
<TITLE>Device Driver Models</TITLE>

<PARA>
There are several ways in which <!-- <index></index> -->device drivers
may be built. The exact model chosen will depend on the properties of
the device and the behavior desired. There are three basic models that
may be adopted.
</PARA>

<PARA>
The first model is to do all device processing in the ISR.  When it is
invoked the ISR programs the device hardware directly and accesses
data to be transferred directly in memory. The ISR should also call
<FUNCTION>cyg_drv_interrupt_acknowledge()</FUNCTION>.  When it is
finished it may optionally request that its DSR be invoked.  The DSR
does nothing but call <FUNCTION>cyg_drv_cond_signal()</FUNCTION> to
cause a thread to be woken up. Thread level code must call
<FUNCTION>cyg_drv_isr_lock()</FUNCTION>, or
<FUNCTION>cyg_drv_interrupt_mask()</FUNCTION> to prevent ISRs running
while it manipulates shared memory.
</PARA>

<PARA>
The second model is to defer device processing to the DSR.  The ISR
simply prevents further delivery of interrupts by either programming
the device, or by calling
<FUNCTION>cyg_drv_interrupt_mask()</FUNCTION>.  It must then call
<FUNCTION>cyg_drv_interrupt_acknowledge()</FUNCTION> to allow other
interrupts to be delivered and then request that its DSR be
called. When the DSR runs it does the majority of the device handling,
optionally signals a condition variable to wake a thread, and finishes
by calling <FUNCTION>cyg_drv_interrupt_unmask()</FUNCTION> to re-allow
device interrupts. Thread level code uses
<FUNCTION>cyg_drv_dsr_lock()</FUNCTION> to prevent DSRs running while
it manipulates shared memory.  The eCos serial device drivers use this
approach.
</PARA>

<PARA>
The third model is to defer device processing even further to a
thread. The ISR behaves exactly as in the previous model and simply
blocks and acknowledges the interrupt before request that the DSR
run. The DSR itself only calls
<FUNCTION>cyg_drv_cond_signal()</FUNCTION> to wake the thread. When
the thread awakens it performs all device processing, and has full
access to all kernel facilities while it does so. It should finish by
calling <FUNCTION>cyg_drv_interrupt_unmask()</FUNCTION> to re-allow
device interrupts.  The eCos ethernet device drivers are written to
this model.
</PARA>

<PARA>
The first model is good for devices that need immediate processing and
interact infrequently with thread level. The second model trades a
little latency in dealing with the device for a less intrusive
synchronization mechanism. The last model allows device processing to
be scheduled with other threads and permits more complex device
handling.
</PARA>

</SECTION>

<!-- }}} -->
<!-- {{{ Synchronization Levels -->

<SECTION id="devapi-synchronization-levels">
<TITLE>Synchronization Levels</TITLE>

<PARA>
Since it would be dangerous for an ISR or DSR to make a call
that might reschedule the current thread (by trying to lock a mutex
for example) all functions in this API have an associated synchronization
level. These levels are:
</PARA>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Thread</TERM>
    <LISTITEM>
      <PARA>
      This function may only be called from within threads. This is
      usually the client code that makes calls into the device driver.
      In a non-kernel configuration, this will be code running at the
      default non-interrupt level.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM>DSR</TERM>
    <LISTITEM>
      <PARA>
      This function may be called by either DSR or thread code.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
    <TERM>ISR</TERM>
    <LISTITEM>
      <PARA>
      This function may be called from ISR, DSR or thread code.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

<PARA>
The following table shows, for each API function, the levels
at which is may be called:
</PARA>

<PROGRAMLISTING role="ascii-art">
                                  Callable from:
Function                       ISR     DSR    Thread
-------------------------------------------------------------------------

cyg_drv_isr_lock                X       X       X
cyg_drv_isr_unlock              X       X       X
cyg_drv_spinlock_init                           X
cyg_drv_spinlock_destroy                        X
cyg_drv_spinlock_spin           X       X       X
cyg_drv_spinlock_clear          X       X       X
cyg_drv_spinlock_try            X       X       X
cyg_drv_spinlock_test           X       X       X
cyg_drv_spinlock_spin_intsave   X       X       X
cyg_drv_spinlock_clear_intsave  X       X       X
cyg_drv_dsr_lock                        X       X
cyg_drv_dsr_unlock                      X       X
cyg_drv_mutex_init                              X
cyg_drv_mutex_destroy                           X
cyg_drv_mutex_lock                              X
cyg_drv_mutex_trylock                           X
cyg_drv_mutex_unlock                            X
cyg_drv_mutex_release                           X
cyg_drv_cond_init                               X
cyg_drv_cond_destroy                            X
cyg_drv_cond_wait                               X
cyg_drv_cond_signal                     X       X
cyg_drv_cond_broadcast                  X       X
cyg_drv_interrupt_create                        X
cyg_drv_interrupt_delete                        X
cyg_drv_interrupt_attach        X       X       X
cyg_drv_interrupt_detach        X       X       X
cyg_drv_interrupt_mask          X       X       X
cyg_drv_interrupt_unmask        X       X       X
cyg_drv_interrupt_acknowledge   X       X       X
cyg_drv_interrupt_configure     X       X       X
cyg_drv_interrupt_level         X       X       X
cyg_drv_interrupt_set_cpu       X       X       X
cyg_drv_interrupt_get_cpu       X       X       X

</PROGRAMLISTING>
</SECTION>

<!-- }}} -->
<!-- {{{ The API -->

<SECTION id="devapi-api">
<TITLE>The API</TITLE>

<PARA>
This section details the <!-- <index></index> -->Driver Kernel
Interface. Note that most of these functions are identical to Kernel C
API calls, and will in most configurations be wrappers for them. In
non-kernel configurations they will be supported directly by the HAL,
or by code to emulate the required behavior.
</PARA>

<PARA>This API is defined in the header file
<FILENAME>&lt;cyg/hal/drv_api.h&gt;</FILENAME>.
</PARA>

<!-- {{{ cyg_drv_isr_lock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_isr_lock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_isr_lock()</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <PARA>
      Disables delivery of interrupts, preventing all ISRs running.  This
      function maintains a counter of the number of times it is
      called.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_isr_unlock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_isr_unlock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_isr_unlock()</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Re-enables delivery of interrupts, allowing ISRs to
      run. This function decrements the counter maintained by
      <FUNCTION>cyg_drv_isr_lock()</FUNCTION>, and only re-allows
      interrupts when it goes to zero. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_init -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_init</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
<programlisting>
void cyg_drv_spinlock_init(cyg_spinlock_t *lock, cyg_bool_t locked )
</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to initialize</PARA>
      <PARA><parameter>locked</parameter> - initial state of lock</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Initialize a spinlock. The <parameter>locked</parameter>
      argument indicates how the spinlock should be initialized:
      <literal>TRUE</literal> for locked or <literal>FALSE</literal>
      for unlocked state.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_destroy -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_destroy</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_spinlock_destroy(cyg_spinlock_t *lock )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock destroy</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Destroy a spinlock that is no longer of use. There should be no
      CPUs attempting to claim the lock at the time this function is
      called, otherwise the behavior is undefined.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_spin -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_spin</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_spinlock_spin(cyg_spinlock_t *lock )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to claim</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Claim a spinlock, waiting in a busy loop until it is
      available. Wherever this is called from, this operation
      effectively pauses the CPU until it succeeds. This operations
      should therefore be used sparingly, and in situations where
      deadlocks/livelocks cannot occur. Also see
      <function>cyg_drv_spinlock_spin_intsave()</function>.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_clear -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_clear</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_spinlock_clear(cyg_spinlock_t *lock )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to clear </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Clear a spinlock. This clears the spinlock and allows another
      CPU to claim it. If there is more than one CPU waiting in
      <function>cyg_drv_spinlock_spin()</function> then just one of
      them will be allowed to proceed.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_try -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_try</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>cyg_bool_t cyg_drv_spinlock_try(cyg_spinlock_t *lock )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to try</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA><literal>TRUE</literal> if the spinlock was claimed,
      <literal>FALSE</literal> otherwise.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Try to claim the spinlock without waiting. If the spinlock could
      be claimed immediately then <literal>TRUE</literal> is
      returned. If the spinlock is already claimed then the result is
      <literal>FALSE</literal>.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_test -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_test</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>cyg_bool_t cyg_drv_spinlock_test(cyg_spinlock_t *lock )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to test</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA><literal>TRUE</literal> if the spinlock is available,
      <literal>FALSE</literal> otherwise.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      Inspect the state of the spinlock. If the spinlock is not locked
      then the result is <literal>TRUE</literal>. If it is locked then
      the result will be <literal>FALSE</literal>.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_spin_intsave -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_spin_intsave</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
<programlisting>
void cyg_drv_spinlock_spin_intsave(cyg_spinlock_t *lock,
                                   cyg_addrword_t *istate )
</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to claim</PARA>
      <PARA><parameter>istate</parameter> - pointer to interrupt state save location</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      This function behaves exactly like
      <function>cyg_drv_spinlock_spin()</function> except that it also
      disables interrupts before attempting to claim the lock. The
      current interrupt enable state is saved in
      <parameter>*istate</parameter>. Interrupts remain disabled once
      the spinlock had been claimed and must be restored by calling
      <function>cyg_drv_spinlock_clear_intsave()</function>.
      </para>
      <para>
      In general, device drivers should use this function to claim and
      release spinlocks rather than the
      non-<function>_intsave()</function> variants, to ensure proper
      exclusion with code running on both other CPUs and this CPU.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_spinlock_clear_intsave -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_spinlock_clear_intsave</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
<programlisting>
void cyg_drv_spinlock_clear_intsave( cyg_spinlock_t *lock,
                                     cyg_addrword_t istate )
</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>lock</parameter> - pointer to spinlock to clear </PARA>
      <PARA><parameter>istate</parameter> - interrupt state to restore </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <para>
      This function behaves exactly like
      <function>cyg_drv_spinlock_clear()</function> except that it
      also restores an interrupt state saved by
      <function>cyg_drv_spinlock_spin_intsave()</function>. The
      <parameter>istate</parameter> argument must have been
      initialized by a previous call to
      <function>cyg_drv_spinlock_spin_intsave()</function>.
      </para>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_dsr_lock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_dsr_lock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_dsr_lock()</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>DSR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Disables scheduling of DSRs. This function maintains a
      counter of the number of times it has been called. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_dsr_unlock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_dsr_unlock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_dsr_unlock()</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>		</PARA>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>DSR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Re-enables scheduling of DSRs. This function decrements
      the counter incremented by
      <FUNCTION>cyg_drv_dsr_lock()</FUNCTION>.  DSRs are only allowed
      to be delivered when the counter goes to zero. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_init -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_init</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_mutex_init(cyg_drv_mutex_t *mutex)</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>mutex</parameter> - pointer to mutex to initialize</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Initialize the mutex pointed to by the
      <literal>mutex</literal> argument. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_destroy -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_destroy</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_mutex_destroy( cyg_drv_mutex_t *mutex )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>mutex</parameter> - pointer to mutex to destroy</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Destroy the mutex pointed to by the
      <parameter>mutex</parameter> argument. The mutex should be unlocked
      and there should be no threads waiting to lock it when this call
      in made.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_lock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_lock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>cyg_bool cyg_drv_mutex_lock( cyg_drv_mutex_t *mutex )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>mutex</parameter> - pointer to mutex to lock</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA><literal>TRUE</literal> it the thread has claimed the
      lock, <literal>FALSE</literal> otherwise.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Attempt to lock the mutex pointed to by the
      <parameter>mutex</parameter> argument.  If the mutex is already
      locked by another thread then this thread will wait until that
      thread is finished. If the result from this function is
      <literal>FALSE</literal> then the thread was broken out of its
      wait by some other thread. In this case the mutex will not have
      been locked. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_trylock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_trylock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
      <PARA><programlisting>cyg_bool cyg_drv_mutex_trylock( cyg_drv_mutex_t *mutex )</programlisting></PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>mutex</parameter> - pointer to mutex to lock</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA><literal>TRUE</literal> if the mutex has been locked,
      <literal>FALSE</literal> otherwise. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description:</TERM>
    <LISTITEM>
      <PARA>Attempt to lock the mutex pointed to by the
      <parameter>mutex</parameter> argument without waiting. If the
      mutex is already locked by some other thread then this function
      returns <literal>FALSE</literal>. If the function can lock the
      mutex without waiting, then <literal>TRUE</literal> is
      returned. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_unlock -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_unlock</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_mutex_unlock( cyg_drv_mutex_t *mutex )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>mutex</parameter> - pointer to mutex to unlock</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
    <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Unlock the mutex pointed to by the
      <parameter>mutex</parameter> argument. If there are any threads
      waiting to claim the lock, one of them is woken up to try and
      claim it. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_mutex_release -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_mutex_release</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_mutex_release( cyg_drv_mutex_t *mutex )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><literal>mutex</literal> - pointer to mutex to release</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Release all threads waiting on the mutex pointed to by the
      <parameter>mutex</parameter> argument. These threads will return
      from <FUNCTION>cyg_drv_mutex_lock()</FUNCTION> with a
      <literal>FALSE</literal> result and will not have claimed the
      mutex. This function has no effect on any thread that may have
      the mutex claimed. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_cond_init -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_cond_init</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting> void cyg_drv_cond_init( cyg_drv_cond_t *cond, cyg_drv_mutex_t *mutex )
	      </programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>cond</parameter> - condition variable to initialize</PARA>
      <PARA><parameter>mutex</parameter> - mutex to associate with this condition variable</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Initialize the condition variable pointed to by the
      <parameter>cond</parameter> argument.  The
      <parameter>mutex</parameter> argument must point to a mutex with
      which this condition variable is associated. A thread may only
      wait on this condition variable when it has already locked the
      associated mutex. Waiting will cause the mutex to be unlocked,
      and when the thread is reawakened, it will automatically claim
      the mutex before continuing. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_cond_destroy -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_cond_destroy</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting> void cyg_drv_cond_destroy( cyg_drv_cond_t *cond )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>cond</parameter> - condition variable to destroy</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Destroy the condition variable pointed to by the
      <parameter>cond</parameter> argument. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_cond_wait -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_cond_wait</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_cond_wait( cyg_drv_cond_t *cond )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>cond</parameter> - condition variable to wait on</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Wait for a signal on the condition variable pointed to by
      the <parameter>cond</parameter> argument. The thread must have
      locked the associated mutex, supplied in
      <function>cyg_drv_cond_init()</function>, before waiting on this
      condition variable. While the thread waits, the mutex will be
      unlocked, and will be re-locked before this function returns. It
      is possible for threads waiting on a condition variable to
      occasionally wake up spuriously. For this reason it is necessary
      to use this function in a loop that re-tests the condition each
      time it returns. Note that this function performs an implicit
      scheduler unlock/relock sequence, so that it may be used within
      an explicit
      <literal>cyg_drv_dsr_lock()...cyg_drv_dsr_unlock()</literal>
      structure.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_cond_signal -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_cond_signal</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_cond_signal( cyg_drv_cond_t *cond )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>cond</parameter> - condition variable to signal</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>DSR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Signal the condition variable pointed to by the <parameter>cond</parameter>
      argument.  If there are any threads waiting on this variable at
      least one of them will be awakened. Note that in some
      configurations there may not be any difference between this
      function and <FUNCTION>cyg_drv_cond_broadcast()</FUNCTION>.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_cond_broadcast -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_cond_broadcast</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_cond_broadcast( cyg_drv_cond_t *cond )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>cond</parameter> - condition variable to broadcast to</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>DSR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Signal the condition variable pointed to by the
      <parameter>cond</parameter> argument.  If there are any threads
      waiting on this variable they will all be awakened. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_create -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_create</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
<PROGRAMLISTING>
void cyg_drv_interrupt_create( cyg_vector_t vector,
                               cyg_priority_t priority,
                               cyg_addrword_t data,
                               cyg_ISR_t *isr,
                               cyg_DSR_t *dsr,
                               cyg_handle_t *handle,
                               cyg_interrupt *intr
                             )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to attach to</PARA>
      <PARA><parameter>priority</parameter> - queuing priority</PARA>
      <PARA><parameter>data</parameter> - data pointer</PARA>
      <PARA><parameter>isr</parameter> - interrupt service routine</PARA>
      <PARA><parameter>dsr</parameter> - deferred service routine</PARA>
      <PARA><parameter>handle</parameter> - returned handle</PARA>
      <PARA><parameter>intr</parameter> - put interrupt object here</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Create an interrupt object and returns a handle to it. The
      object contains information about which interrupt vector to use
      and the ISR and DSR that will be called after the interrupt
      object is attached to the vector. The interrupt object will be
      allocated in the memory passed in the
      <parameter>intr</parameter> parameter. The interrupt object is
      not immediately attached; it must be attached with the
      <FUNCTION>cyg_interrupt_attach()</FUNCTION> call. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_delete -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_delete</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting> void cyg_drv_interrupt_delete( cyg_handle_t interrupt )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>interrupt</parameter> - interrupt to delete</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>Thread</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Detach the interrupt from the vector and free the memory
      passed in the <parameter>intr</parameter> argument to
      <FUNCTION>cyg_drv_interrupt_create()</FUNCTION> for
      reuse. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_attach -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_attach</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_attach( cyg_handle_t interrupt )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>interrupt</parameter> - interrupt to attach</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Attach the interrupt to the vector so that interrupts will
      be delivered to the ISR when the interrupt occurs. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_detach -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_detach</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_detach( cyg_handle_t interrupt )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>interrupt</parameter> - interrupt to detach</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Detach the interrupt from the vector so that interrupts
      will no longer be delivered to the ISR. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_mask -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_mask</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_mask(cyg_vector_t vector )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to mask</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller to stop delivery of
      interrupts on the given vector. On architectures which implement
      interrupt priority levels this may also disable all lower
      priority interrupts. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_mask_intunsafe -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_mask_intunsafe</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_mask_intunsafe(cyg_vector_t vector )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to mask</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller to stop delivery of
      interrupts on the given vector. On architectures which implement
      interrupt priority levels this may also disable all lower
      priority interrupts. This version differs from
      <function>cyg_drv_interrupt_mask()</function> in not being
      interrupt safe. So in situations where, for example, interrupts
      are already known to be disabled, this may be called to avoid
      the extra overhead.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_unmask -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_unmask</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_unmask(cyg_vector_t vector )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to unmask</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller to re-allow delivery of
      interrupts on the given <parameter>vector</parameter>. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_unmask_intunsafe -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_unmask_intunsafe</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_unmask_intunsafe(cyg_vector_t vector )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to unmask</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller to re-allow delivery of
      interrupts on the given <parameter>vector</parameter>. This
      version differs from
      <function>cyg_drv_interrupt_unmask()</function> in not being
      interrupt safe.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_acknowledge -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_acknowledge</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <programlisting>void cyg_drv_interrupt_acknowledge( cyg_vector_t vector )</programlisting>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to acknowledge</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Perform any processing required at the interrupt
      controller and in the CPU to cancel the current interrupt
      request on the <parameter>vector</parameter>. An ISR may also
      need to program the hardware of the device to prevent an
      immediate re-triggering of the interrupt. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>
</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_configure -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_configure</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
      <PROGRAMLISTING>
void cyg_drv_interrupt_configure( cyg_vector_t vector,
                                  cyg_bool_t level, 
                                  cyg_bool_t up
                                )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to configure</PARA>
      <PARA><parameter>level</parameter> - level or edge triggered</PARA>
      <PARA><parameter>up</parameter> - rising/falling edge, high/low level</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller with the characteristics
      of the interrupt source. The <parameter>level</parameter>
      argument chooses between level- or edge-triggered
      interrupts. The <parameter>up</parameter> argument chooses
      between high and low level for level triggered interrupts or
      rising and falling edges for edge triggered interrupts. This
      function only works with interrupt controllers that can control
      these parameters. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_level -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_level</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function: 	</TERM>
    <LISTITEM>
<PROGRAMLISTING>
void cyg_drv_interrupt_level( cyg_vector_t vector,
                              cyg_priority_t level
                            )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector to configure</PARA>
      <PARA><parameter>level</parameter> - level to set</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level: 	</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Program the interrupt controller to deliver the given
       interrupt at the supplied priority level. This function only
       works with interrupt controllers that can control this
       parameter.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_set_cpu -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_set_cpu</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
<PROGRAMLISTING>
void cyg_drv_interrupt_set_cpu( cyg_vector_t vector,
                                cyg_cpu_t cpu
                              )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - interrupt vector to route</PARA>
      <PARA><parameter>cpu</parameter> - destination CPU</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>
      This function causes all interrupts on the given vector to be
      routed to the specified CPU. Subsequently, all such interrupts
      will be handled by that CPU. This only works if the underlying
      hardware is capable of performing this kind of routing. This
      function does nothing on a single CPU system.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_drv_interrupt_get_cpu -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_drv_interrupt_get_cpu</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Function:</TERM>
    <LISTITEM>
<PROGRAMLISTING>
cyg_cpu_t cyg_drv_interrupt_set_cpu( cyg_vector_t vector )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Arguments:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - interrupt vector to query</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result:</TERM>
    <LISTITEM>
      <PARA>The CPU to which this vector is routed</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Level:</TERM>
    <LISTITEM>
      <PARA>ISR</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>
      In multi-processor systems this function returns the id of the
      CPU to which interrupts on the given vector are current being
      delivered. In single CPU systems this function returns zero.
      </PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_ISR_t -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_ISR_t</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Type: 	</TERM>
    <LISTITEM>
<PROGRAMLISTING>
typedef cyg_uint32 cyg_ISR_t( cyg_vector_t vector,
                              cyg_addrword_t data
                            )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Fields:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector being delivered</PARA>
      <PARA><parameter>data</parameter> - data value supplied by client</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>Bit mask indicating whether interrupt was handled and
      whether the DSR should be called. </PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Interrupt Service Routine definition. A pointer to a
      function with this prototype is passed to
      <FUNCTION>cyg_interrupt_create()</FUNCTION> when an interrupt
      object is created. When an interrupt is delivered the function
      will be called with the vector number and the data value that
      was passed to <FUNCTION>cyg_interrupt_create()</FUNCTION>.
      </PARA>
      <PARA>The return value is a bit mask containing one or both of the
      following bits: </PARA>
      <variablelist>
	<VARLISTENTRY>
	  <TERM>CYG_ISR_HANDLED 	</TERM>
	  <LISTITEM>
	    <PARA>indicates that the interrupt was handled by this
	    ISR. It is a configuration option whether this will
	    prevent further ISR being run. </PARA>
	  </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	  <TERM>CYG_ISR_CALL_DSR 	</TERM>
	  <LISTITEM>
	    <PARA>causes the DSR that was passed to
	    <FUNCTION>cyg_interrupt_create()</FUNCTION> to be
	    scheduled to be called.</PARA>
	  </LISTITEM>
	</VARLISTENTRY>
      </variablelist>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->
<!-- {{{ cyg_DSR_t -->

<SECTION>
<TITLE><!-- <index></index> -->cyg_DSR_t</TITLE>

<VARIABLELIST>
  <VARLISTENTRY>
    <TERM>Type: 	</TERM>
    <LISTITEM>
<PROGRAMLISTING>
typedef void cyg_DSR_t( cyg_vector_t vector,
                        cyg_ucount32 count,
                        cyg_addrword_t data
                      )
</PROGRAMLISTING>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Fields:</TERM>
    <LISTITEM>
      <PARA><parameter>vector</parameter> - vector being delivered</PARA>
      <PARA><parameter>count</parameter> - number of times DSR has been scheduled</PARA>
      <PARA><parameter>data</parameter> - data value supplied by client</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Result: 	</TERM>
    <LISTITEM>
      <PARA>None</PARA>
    </LISTITEM>
  </VARLISTENTRY>
  <VARLISTENTRY>
    <TERM>Description: 	</TERM>
    <LISTITEM>
      <PARA>Deferred Service Routine prototype. A pointer to a
      function with this prototype is passed to
      <FUNCTION>cyg_interrupt_create()</FUNCTION> when an interrupt
      object is created. When the ISR requests the scheduling of its
      DSR, this function will be called at some later point. In
      addition to the <parameter>vector</parameter> and
      <parameter>data</parameter> arguments, which will be the same as
      those passed to the ISR, this routine is also passed a
      <parameter>count</parameter> of the number of times the ISR has
      requested that this DSR be scheduled.  This counter is zeroed
      each time the DSR actually runs, so it indicates how many
      interrupts have occurred since it last ran.</PARA>
    </LISTITEM>
  </VARLISTENTRY>
</VARIABLELIST>

</SECTION>

<!-- }}} -->

</SECTION>

<!-- }}} -->

</CHAPTER>

<!-- }}} -->


</PART>