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>
Support pm_ops in the AMBA bus, required to allow drivers to use runtime pm.
The implementation of AMBA bus pm ops is based on the platform bus
implementation.
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Now that the bus level code deals with a const id table, we can also
make the ID table in the amba_driver structure also const.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Make Primecell driver probe functions take a const pointer to their
ID tables. Drivers should never modify their ID tables in their
probe handler.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The ARM CLCD PL110 controller in TFT mode provides two output formats
based on whether the controller is in 24bpp mode or not - either 5551
or 888. PL111 augments this with a 444 and 565 modes.
Some implementations provide an external MUX on the PL110 output to
reassign the bits to achieve 565 mode.
Provide a system of capability flags to allow the CLCD driver to work
out what is supported by each panel and board, and therefore which
display formats are permitted.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Instead of matching the entire peripheral ID, match against
just the part number using the amba_xxx() macros.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Based on a patch from Linus Walleij.
Add dmaengine based support for DMA to the MMCI driver, using the
Primecell DMA engine interface. The changes over Linus' driver are:
- rename txsize_threshold to dmasize_threshold, as this reflects the
purpose more.
- use 'mmci_dma_' as the function prefix rather than 'dma_mmci_'.
- clean up requesting of dma channels.
- don't release a single channel twice when it's shared between tx and rx.
- get rid of 'dma_enable' bool - instead check whether the channel is NULL.
- detect incomplete DMA at the end of a transfer. Some DMA controllers
(eg, PL08x) are unable to be configured for scatter DMA and also listen
to all four DMA request signals [BREQ,SREQ,LBREQ,LSREQ] from the MMCI.
They can do one or other but not both. As MMCI uses LBREQ/LSREQ for the
final burst/words, PL08x does not transfer the last few words.
- map and unmap DMA buffers using the DMA engine struct device, not the
MMCI struct device - the DMA engine is doing the DMA transfer, not us.
- avoid double-unmapping of the DMA buffers on MMCI data errors.
- don't check for negative values from the dmaengine tx submission
function - Dan says this must never fail.
- use new dmaengine helper functions rather than using the ugly function
pointers directly.
- allow DMA code to be fully optimized away using dma_inprogress() which
is defined to constant 0 if DMA engine support is disabled.
- request maximum segment size from the DMA engine struct device and
set this appropriately.
- removed checking of buffer alignment - the DMA engine should deal with
its own restrictions on buffer alignment, not the individual DMA engine
users.
- removed setting DMAREQCTL - this confuses some DMA controllers as it
causes LBREQ to be asserted for the last seven transfers, rather than
six SREQ and one LSREQ.
- removed burst setting - the DMA controller should not burst past the
transfer size required to complete the DMA operation.
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx: (63 commits)
ARM: PL08x: cleanup comments
Update CONFIG_MD_RAID6_PQ to CONFIG_RAID6_PQ in drivers/dma/iop-adma.c
ARM: PL08x: fix a warning
Fix dmaengine_submit() return type
dmaengine: at_hdmac: fix race while monitoring channel status
dmaengine: at_hdmac: flags located in first descriptor
dmaengine: at_hdmac: use subsys_initcall instead of module_init
dmaengine: at_hdmac: no need set ACK in new descriptor
dmaengine: at_hdmac: trivial add precision to unmapping comment
dmaengine: at_hdmac: use dma_address to program DMA hardware
pch_dma: support new device ML7213 IOH
ARM: PL08x: prevent dma_set_runtime_config() reconfiguring memcpy channels
ARM: PL08x: allow dma_set_runtime_config() to return errors
ARM: PL08x: fix locking between prepare function and submit function
ARM: PL08x: introduce 'phychan_hold' to hold on to physical channels
ARM: PL08x: put txd's on the pending list in pl08x_tx_submit()
ARM: PL08x: rename 'desc_list' as 'pend_list'
ARM: PL08x: implement unmapping of memcpy buffers
ARM: PL08x: store prep_* flags in async_tx structure
ARM: PL08x: shrink srcbus/dstbus in txd structure
...
drivers/dma/amba-pl08x.c: In function 'pl08x_start_txd':
drivers/dma/amba-pl08x.c:205: warning: dereferencing 'void *' pointer
We never dereference llis_va aside from assigning it to a struct
pl08x_lli pointer or calculating the address of array element 0.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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 PL08x driver holds on to the channel lock with interrupts disabled
between the prepare and the subsequent submit API functions. This
means that the locking state when the prepare function returns is
dependent on whether it suceeeds or not.
It did this to ensure that the physical channel wasn't released, and
as it used to add the descriptor onto the pending list at prepare time
rather than submit time.
Now that we have reorganized the code to remove those reasons, we can
now safely release the spinlock at the end of preparation and reacquire
it in our submit function.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Introduce 'phychan_hold' to hold on to physical DMA channels while we're
preparing a new descriptor for it. This will be incremented when we
allocate a physical channel and set the MUX registers during the
preparation of the TXD, and will only be decremented when the TXD is
submitted.
This prevents the physical channel being given up before the new TXD
is placed on the queue.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This 'desc_list' is actually a list of pending descriptors, so name
it after its function (pending list) rather than what it contains
(descriptors).
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Platforms need to be able to control which AHB master interface is used,
as each AHB master interface may be asymetric. Allow the interfaces
used for fetching LLIs, memory, and each peripheral to be configured
individually.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The ccfg register is used to configure the channel parameters - the type
and direction of transfer, the flow control signal and IRQ mask enables.
The type and direction of transfer is known in the relevent prep_*
function where a txd is created. The IRQ mask enables are always set,
and the flow control signals are always set when we start processing a
txd according to phychan->signal.
If we store the ccfg value in the txd structure, we can avoid modifying
platform data - and even having it in platform data at all.
So, remove it from platform data too.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
As we now have all the code accessing the phychan {csrc,cdst,clli,cctl,
ccfg} members in one function, there's no point storing the data into
the struct. Get rid of the struct members. Re-order the register dump
in the dev_dbg() to reflect the order we write the registers to the DMA
device.
The txd {csrc,cdst,clli,cctl} values are duplicates of the lli[0]
values, so there's no point duplicating these either. Program the DMAC
registers directly from the lli[0] values.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
