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>
The ST Micro derivates have several extra interesting registers
that we may soon use for something interesting so may just as
well define them in the header.
Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Implementation of the ST-Ericsson baudrate extension in the PL011
block. In this modified variant it is possible to change the
sampling factor from 16 to 8, and thanks to this we can get higher
baudrates while still using the same peripheral clock.
Also replace the simple division to determine the baud divisor
with DIV_ROUND_CLOSEST() rather than a simple integer division.
Cc: Alessandro Rubini <rubini@unipv.it>
Cc: Jerzy Kasenberg <jerzy.kasenberg@tieto.com>
Signed-off-by: Marcin Mielczarczyk <marcin.mielczarczyk@tieto.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
In the ST-Ericsson version of the PL011 the TX and RX have different
control registers.
Cc: Alessandro Rubini <rubini@unipv.it>
Signed-off-by: Marcin Mielczarczyk <marcin.mielczarczyk@tieto.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (417 commits)
MAINTAINERS: EB110ATX is not ebsa110
MAINTAINERS: update Eric Miao's email address and status
fb: add support of LCD display controller on pxa168/910 (base layer)
[ARM] 5552/1: ep93xx get_uart_rate(): use EP93XX_SYSCON_PWRCNT and EP93XX_SYSCON_PWRCN
[ARM] pxa/sharpsl_pm: zaurus needs generic pxa suspend/resume routines
[ARM] 5544/1: Trust PrimeCell resource sizes
[ARM] pxa/sharpsl_pm: cleanup of gpio-related code.
[ARM] pxa/sharpsl_pm: drop set_irq_type calls
[ARM] pxa/sharpsl_pm: merge pxa-specific code into generic one
[ARM] pxa/sharpsl_pm: merge the two sharpsl_pm.c since it's now pxa specific
[ARM] sa1100: remove unused collie_pm.c
[ARM] pxa: fix the conflicting non-static declarations of global_gpios[]
[ARM] 5550/1: Add default configure file for w90p910 platform
[ARM] 5549/1: Add clock api for w90p910 platform.
[ARM] 5548/1: Add gpio api for w90p910 platform
[ARM] 5551/1: Add multi-function pin api for w90p910 platform.
[ARM] Make ARM_VIC_NR depend on ARM_VIC
[ARM] 5546/1: ARM PL022 SSP/SPI driver v3
ARM: OMAP4: SMP: Update defconfig for OMAP4430
ARM: OMAP4: SMP: Enable SMP support for OMAP4430
...
This header is sometimes included in the uncompress stage to get
register values, but no <linux/amba/bus.h> can be included there.
So declare "struct amba_device" here before using it in a prototype.
Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The Nomadik 8815 SoC has a slightly modified version of the PL011 block.
The patch uses the different ID value as a key to select a vendor
structure that is used to keep track of the differences, as suggested
by Russell King.
Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The amba-pl010 hardware does not provide RTS and DTR control lines; it
is expected that these will be implemented using GPIO. Allow platforms
to supply a function to implement manipulation of modem control lines.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Since the ARM AMBA bus is used on MIPS as well as ARM, we need
to make the bus available for other architectures to use. Move
the AMBA include files from include/asm-arm/hardware/ to
include/linux/amba/
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
