linux-toradex.git/drivers/w1/w1_io.c, branch v3.7.4

w1: Disable irqs during 1-wire bus operations, extend 1-wire reset pulse

2012-04-11T23:44:10+00:00

This patch offers the possibility to disables irqs during w1_write_bit()
and w1_reset_bus() operations as timing requirements are very strict for
the 1-wire bus protocol. Per default interrupts are enabled but can be
disabled via the module parameter "w1_disable_irqs".

Extend 1-wire reset pulse length from 480us to 500us as 480us is the
minimum requirement for the 1-wire reset/presence pulse.

Signed-off-by: Markus Franke 
Acked-by: Evgeniy Polyakov 
Signed-off-by: Greg Kroah-Hartman

w1: disable irqs in critical section

2011-11-02T23:07:03+00:00

Interrupting w1_delay() in w1_read_bit() results in missing the low level
on the w1 line and receiving "1" instead of "0".

Add local_irq_save()/local_irq_restore() around the critical section

Signed-off-by: Jan Weitzel 
Acked-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

MAINTAINERS: Evgeniy has moved

2011-08-25T23:25:33+00:00

Signed-off-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

w1: add 1-wire (w1) reset and resume command API support

2011-05-27T00:12:38+00:00

The first patch adds generic functionnality to w1_io for Resume Command
[A5h] lots of slaves support.  I found it useful for multi-commands/reset
workflows with the same slave on a multi-slave bus.

This DS2408 w1 slave driver is not complete for all the features of the
chip, but its sufficient if you use it as a simple IO expander.  Enjoy!

The ds1wm had Kconfig dependencies towards ARM && HAVE_CLK.  I took them
out since I was using the ds1wm on an x86_64 platform (ds1wm in a FPGA
through pcie) and found them irrelevant.

The clock freq/divisors at the top of ds1wm.c did not have the MSB set to
1.  This bit is CLK_EN which turns the whole prescaler and dividers on.
The driver never mentionned this bit either, so I just included this bit
right in the table entries.  I also took the liberty to add a couple of
entries to the table.  The spec doesn't explicitely mentions these
possibilities but the description and examination of the core shows the
prescalers & dividers can be used for more than the table explicitely
shows.  The table I enlarged still doesn't cover all possibilities, but
it's a good start.

I also made a few tweaks to a couple of the read and write algorithms
which made sense while I had my head very deep in the ds1wm documentation.
 We stressed it a lot with 10+ slaves on the bus, many ds2408, ds2431 and
ds2433 at the same time doing extensive interaction.  It proved quite
stable in our production environment.

This patch:

Add generic functionnality to w1_io for Resume Command [A5h] lots of
slaves support.

Signed-off-by: Jean-François Dagenais 
Cc: Evgeniy Polyakov 
Cc: Szabolcs Gyurko 
Cc: Matt Reimer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

w1: coding style cleanups in w1_io.c

2009-04-03T02:05:04+00:00

This fixes a number of coding style issues I stubled over.

Acked-by: Evgeniy Polyakov 
Signed-off-by: Daniel Mack 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

w1: add touch block command

2009-01-08T16:31:13+00:00

Writes and returns sampled data back to userspace.

Signed-off-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

w1: fix slave selection on big-endian systems

2008-12-23T23:58:21+00:00

During test of the w1-gpio driver i found that in "w1.c:679
w1_slave_found()" the device id is converted to little-endian with
"cpu_to_le64()", but its not converted back to cpu format in "w1_io.c:293
w1_reset_select_slave()".

Based on a patch created by Andreas Hummel.

[akpm@linux-foundation.org: remove unneeded cast]
Reported-by: Andreas Hummel 
Signed-off-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

w1: export w1_read_8 function

2008-11-13T01:17:18+00:00

Export the w1_read_8 function for use of drivers.  The OMAP HDQ
driver(drivers/w1/masters/omap_hdq.c) uses this function.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Madhusudhan Chikkature
Acked-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

W1: w1_io.c reset comments and msleep

2008-10-16T18:21:50+00:00

w1_reset_bus, added some comments about the timing and switched to msleep
for the later delay.  I don't have the hardware to test the sleep after
reset change.  The one wire doesn't have a timing requirement between
commands so it is fine.  I do have the USB hardware and it would be in big
trouble with 10ms interrupt transfers to find that the reset completed.

Signed-off-by: David Fries 
Signed-off-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

W1: feature, enable hardware strong pullup

2008-10-16T18:21:49+00:00

Add a strong pullup option to the w1 system.  This supplies extra power
for parasite powered devices.  There is a w1_master_pullup sysfs entry and
enable_pullup module parameter to enable or disable the strong pullup.

The one wire bus requires at a minimum one wire and ground.  The common
wire is used for sending and receiving data as well as supplying power to
devices that are parasite powered of which temperature sensors can be one
example.  The bus must be idle and left high while a temperature
conversion is in progress, in addition the normal pullup resister on
larger networks or even higher temperatures might not supply enough power.
 The pullup resister can't provide too much pullup current, because
devices need to pull the bus down to write a value.  This enables the
strong pullup for supported hardware, which can supply more current when
requested.  Unsupported hardware will just delay with the bus high.

The hardware USB 2490 one wire bus master has a bit on some commands which
will enable the strong pullup as soon as the command finishes executing.
To use strong pullup, call the new w1_next_pullup function to register the
duration.  The next write command will call set_pullup before sending the
data, and reset the duration to zero once it returns.

Switched from simple_strtol to strict_strtol.

Signed-off-by: David Fries 
Cc: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds