Add (incomplete) support for the ZTE UART to the AMBA PL011 driver.
This is similar to the ARM and ST variants, except it has a different
register address layout, and requires 32-bit accesses to the registers.
Use the newly introduced register tables and access size support to
cope with these differences.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 8cd90e50d1408c65c355084b1c7f8f9085f49c6b as with
this patch the serial console is broken on lots of platforms.

Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Support ZTE uart with some registers differing offset.
Probe as platform device for not AMBA IP ID is
available on ZTE uart.

Signed-off-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Correct common misspelling of "identify" as "indentify" throughout
the kernel

Signed-off-by: Maxime Jayat <maxime@artisandeveloppeur.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

In DMA support, The received data is not pushed to tty until the DMA buffer
is filled. But some megabyte rate chips such as BT expect fast response and
data should be pushed immediately. In order to fix this issue, We suggest
the use of the timer for polling DMA buffer.
In our test, no data loss occurred at high-baudrate as compared with interrupt-
driven (We tested with 3Mbps).
We changes:

- We add timer for polling. If we set poll_timer to 10, every 10ms,
 timer handler checks the residue in the dma buffer and transfer data
 to the tty. Also, last_residue is updated for the next polling.

- poll_timeout is used to prevent the timer's system cost.
  If poll_timeout is set to 3000 and no data is received in 3 seconds,
  we inactivate poll timer and driver falls back to interrupt-driven.
  When data is received again in FIFO and UART irq is occurred, we switch
  back to DMA mode and start polling.

- We use consistent DMA mappings to avoid from the frequent cache operation
  of the timer function for default.

- pl011_dma_rx_chars is modified. the pending size is recalculated because
  data can be taken by polling.

- the polling time is adjusted if dma rx poll is enabled but no rate is
  specified. Ideal polling interval to push 1 character at every interval
  is the reciprocal of 'baud rate / 10 line bits per character / 1000 ms
  per sec'. But It is very aggressive to system. Experimentally,
 '10000000 / baud' is suitable to receive dozens of characters. the poll rate
 can be specified statically by dma_rx_poll_rate of the platform data as well.

Changes compared to v1:
 - Use of consistent DMA mappings.
 - Added dma_rx_poll_rate in platform data to specify the polling interval.
 - Added dma_rx_poll_timeout in platform data to specify the polling timeout.

Changes compared to v2:
 - Use of consistent DMA mappings for default.
 - Added dma_rx_poll_enable in platform data to adjust the polling time
   according to the baud rate.
 - remove unnecessary lock from the polling function.

Signed-off-by: Chanho Min <chanho.min@lge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since commit 4fd0690bb0c3955983560bb2767ee82e2b197f9b
"serial: pl011: implement workaround for CTS clear event issue"
the PL011 UART is no longer at risk to hang up, so get rid
of the callback altogether.

Cc: Rajanikanth H.V <rajanikanth.hv@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial.h uses bool, but its definition is missing, as it doesn't include
types.h. Fix this by including types.h

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

This workaround aims to break the deadlock situation
which raises during continuous transfer of data for long
duration over uart with hardware flow control. It is
observed that CTS interrupt cannot be cleared in uart
interrupt register (ICR). Hence further transfer over
uart gets blocked.

It is seen that during such deadlock condition ICR
don't get cleared even on multiple write. This leads
pass_counter to decrease and finally reach zero. This
can be taken as trigger point to run this UART_BT_WA.

Workaround backups the register configuration, does soft
reset of UART using BIT-0 of PRCC_K_SOFTRST_SET/CLEAR
registers and restores the registers.

This patch also provides support for uart init and exit
function calls if present.

Signed-off-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

ST Micro variants has some specific dma burst threshold compensation,
which allows them to make better use of a DMA controller.  Add support
to set this up.

Based on a patch from Linus Walleij.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Add DMA engine support for transmit to the PL011 driver.  Based on a
patch from Linus Walliej, with the following changes:

- remove RX DMA support.  As PL011 doesn't give us receive timeout
  interrupts, we only get notified of received data when the RX DMA
  has completed.  This rather sucks for interactive use of the TTY.

- remove abuse of completions.  Completions are supposed to be for
  events, not to tell what condition buffers are in.  Replace it with
  a simple 'queued' bool.

- fix locking - it is only safe to access the circular buffer with the
  port lock held.

- only map the DMA buffer when required - if we're ever behind an IOMMU
  this helps keep IOMMU usage down, and also ensures that we're legal
  when we change the scatterlist entry length.

- fix XON/XOFF sending - we must send XON/XOFF characters out as soon
  as possible - waiting for up to 4095 characters in the DMA buffer
  to be sent first is not acceptable.

- fix XON/XOFF receive handling - we need to stop DMA when instructed
  to by the TTY layer, and restart it again when instructed to.  There
  is a subtle problem here: we must not completely empty the circular
  buffer with DMA, otherwise we will not be notified of XON.

- change the 'enable_dma' flag into a 'using DMA' flag, and track
  whether we can use TX DMA by whether the channel pointer is non-NULL.
  This gives us more control over whether we use DMA in the driver.

- we don't need to have the TX DMA buffer continually allocated for
  each port - instead, allocate it when the port starts up, and free
  it when it's shut down.  Update the 'using DMA' flag if we get
  the buffer, and adjust the TTY FIFO size appropriately.

- if we're going to use PIO to send characters, use the existing IRQ
  based functionality rather than reimplementing it.  This also ensures
  we call uart_write_wakeup() at the appropriate time, otherwise we'll
  stall.

- use DMA engine helper functions for type safety.

- fix init when built as a module - we can't have to initcall functions,
  so we must settle on one.  This means we can eliminate the deferred
  DMA initialization.

- there is no need to terminate transfers on a failed prep_slave_sg()
  call - nothing has been setup, so nothing needs to be terminated.
  This avoids a potential deadlock in the DMA engine code
  (tasklet->callback->failed prepare->terminate->tasklet_disable
   which then ends up waiting for the tasklet to finish running.)

- Dan says that the submission callback should not return an error:
  | dma_submit_error() is something I should have removed after commit
  | a0587bcf "ioat1: move descriptor allocation from submit to prep" all
  | errors should be notified by prep failing to return a descriptor
  | handle.  Negative dma_cookie_t values are only returned by the
  | dma_async_memcpy* calls which translate a prep failure into -ENOMEM.
  So remove the error handling at that point.  This also solves the
  potential deadlock mentioned in the previous comment.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>