linux-toradex.git/drivers/tty/serial/amba-pl011.c, branch v3.10.37

serial: amba-pl011: use port lock to guard control register access

2014-01-25T16:27:12+00:00

commit fe43390702a1b5741fdf217063b05c7612b38303 upstream.

When the pl011 is being used for a console, pl011_console_write forces
the control register (CR) to enable the UART for transmission and then
restores this to the original value afterwards. It does this while
holding the port lock.

Unfortunately, when the uart is started or shutdown - say in response to
userland using the serial device for a terminal - then this updates the
control register without any locking.

This means we can have

  pl011_console_write   Save CR
  pl011_startup         Initialise CR, e.g. enable receive
  pl011_console_write   Restore old CR with receive not enabled

this result is a serial port which doesn't respond to any input.

A similar race in reverse could happen when the device is shutdown.

We can fix these problems by taking the port lock when updating CR.

Signed-off-by: Jon Medhurst 
Signed-off-by: Greg Kroah-Hartman

serial: pl011: protect attribute read from NULL platform data struct

2013-05-20T18:54:55+00:00

It's completely feasible that platform data will be empty i.e. when
booting with Device Tree with no device AUXDATA. So we must protect
it's use in these use-cases, or risk a kernel Oops.

Cc: Russell King 
Cc: Jiri Slaby 
Cc: Arnd Bergmann 
Signed-off-by: Lee Jones 
Reviewed-by: Linus Walleij 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'cleanup-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

2013-05-07T18:22:14+00:00

Pull ARM SoC late cleanups from Arnd Bergmann:
 "These are cleanups and smaller changes that either depend on earlier
  feature branches or came in late during the development cycle.  We
  normally try to get all cleanups early, so these are the exceptions:

   - A follow-up on the clocksource reworks, hopefully the last time we
     need to merge clocksource subsystem changes through arm-soc.

     A first set of patches was part of the original 3.10 arm-soc
     cleanup series because of interdependencies with timer drivers now
     moved out of arch/arm.

   - Migrating the SPEAr13xx platform away from using auxdata for DMA
     channel descriptions towards using information in device tree,
     based on the earlier SPEAr multiplatform series

   - A few follow-ups on the Atmel SAMA5 support and other changes for
     Atmel at91 based on the larger at91 reworks.

   - Moving the armada irqchip implementation to drivers/irqchip

   - Several OMAP cleanups following up on the larger series already
     merged in 3.10."

* tag 'cleanup-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (50 commits)
  ARM: OMAP4: change the device names in usb_bind_phy
  ARM: OMAP2+: Fix mismerge for timer.c between ff931c82 and da4a686a
  ARM: SPEAr: conditionalize SMP code
  ARM: arch_timer: Silence debug preempt warnings
  ARM: OMAP: remove unused variable
  serial: amba-pl011: fix !CONFIG_DMA_ENGINE case
  ata: arasan: remove the need for platform_data
  ARM: at91/sama5d34ek.dts: remove not needed compatibility string
  ARM: at91: dts: add MCI DMA support
  ARM: at91: dts: add i2c dma support
  ARM: at91: dts: set #dma-cells to the correct value
  ARM: at91: suspend both memory controllers on at91sam9263
  irqchip: armada-370-xp: slightly cleanup irq controller driver
  irqchip: armada-370-xp: move IRQ handler to avoid forward declaration
  irqchip: move IRQ driver for Armada 370/XP
  ARM: mvebu: move L2 cache initialization in init_early()
  devtree: add binding documentation for sp804
  ARM: integrator-cp: convert use CLKSRC_OF for timer init
  ARM: versatile: use OF init for sp804 timer
  ARM: versatile: add versatile dtbs to dtbs target
  ...

serial: amba-pl011: fix !CONFIG_DMA_ENGINE case

2013-04-20T07:40:33+00:00

I changed the prototype of the function earlier but only
in the section for CONFIG_DMA_ENGINE, not the alternative.
This makes the driver build again, e.g. for vexpress_defconfig.

Signed-off-by: Arnd Bergmann

ARM: PL011: add support for extended FIFO-size of PL011-r1p5

2013-04-17T17:15:21+00:00

The latest r1p5-revision of the ARM PL011 UART has 32-byte FIFOs,
while all earlier ones have 16-byte FIFOs. This patch suggests
a way to set the FIFO-size correctly & flexibly by using a member
function named get_fifosize, rather than using the fifosize member
variable. The function takes the UARTPeriphID, and returns the
correct FIFO size.

Signed-off-by: Jongsung Kim 
Signed-off-by: Greg Kroah-Hartman

amba-pl011: fix build error if CONFIG_DMA_ENGINE is not enabled

2013-04-03T18:34:55+00:00

Following patch will fix build error if CONFIG_DMA_ENGINE is unset.

Reported-by: Stephen Rothwell 
Signed-off-by: Chanho Min 
Signed-off-by: Greg Kroah-Hartman

ARM: PL011: Add support for Rx DMA buffer polling.

2013-03-29T16:20:05+00:00

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 
Signed-off-by: Greg Kroah-Hartman

serial: pl011: use generic DMA slave configuration if possible

2013-03-12T16:56:09+00:00

With the new OF DMA binding, it is possible to completely avoid the
need for platform_data for configuring a DMA channel. In cases where the
platform has already been converted, calling dma_request_slave_channel
should get all the necessary information from the device tree.

This also adds a binding document specific to the pl011 controller,
and extends the generic primecell binding to mention "dmas" and other
common properties.

Like the patch that converts the dw_dma controller, this is completely
untested and is looking for someone to try it out.

Signed-off-by: Arnd Bergmann 
Acked-by: Grant Likely 
Acked-by: Greg Kroah-Hartman 
Cc: Russell King 
Cc: Jiri Slaby 
Cc: Viresh Kumar 
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org

TTY: switch tty_flip_buffer_push

2013-01-16T06:30:15+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_string

2013-01-16T06:22:35+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman