The original "Pass the bus number we expect the S3C24XX SPI driver to
attach to via the platform data." [1] patch was mis-sent, and missed two
important parts of the diff, which was to actually set the bus_num field
and add the relevant field to the platform data.
The previous commit 50f426b55d promised to
add a bus_num field, but failed to include the two hunks that added this
field to include/asm-arm/arch-s3c2410/spi.h and then pass it to the spi
core when creating the new master field in drivers/spi/spi_s3c24xx.c.
[1] git commit 50f426b55d
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The block transfer routine in the mpc52xx psc spi driver misinterpret
the datasheet. According to the processor datasheet the chipselect is
held as long as the EOF is not written.
Theoretically blocks of any sizes can be transferred in this way. The
old routine however writes an EOF after every word, which has the size
of size_of_word. This makes the transfer slow.
Also fixed some duplicate code.
Signed-off-by: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add per-device dma_mapping_ops support for CONFIG_X86_64 as POWER
architecture does:
This enables us to cleanly fix the Calgary IOMMU issue that some devices
are not behind the IOMMU (http://lkml.org/lkml/2008/5/8/423).
I think that per-device dma_mapping_ops support would be also helpful for
KVM people to support PCI passthrough but Andi thinks that this makes it
difficult to support the PCI passthrough (see the above thread). So I
CC'ed this to KVM camp. Comments are appreciated.
A pointer to dma_mapping_ops to struct dev_archdata is added. If the
pointer is non NULL, DMA operations in asm/dma-mapping.h use it. If it's
NULL, the system-wide dma_ops pointer is used as before.
If it's useful for KVM people, I plan to implement a mechanism to register
a hook called when a new pci (or dma capable) device is created (it works
with hot plugging). It enables IOMMUs to set up an appropriate
dma_mapping_ops per device.
The major obstacle is that dma_mapping_error doesn't take a pointer to the
device unlike other DMA operations. So x86 can't have dma_mapping_ops per
device. Note all the POWER IOMMUs use the same dma_mapping_error function
so this is not a problem for POWER but x86 IOMMUs use different
dma_mapping_error functions.
The first patch adds the device argument to dma_mapping_error. The patch
is trivial but large since it touches lots of drivers and dma-mapping.h in
all the architecture.
This patch:
dma_mapping_error() doesn't take a pointer to the device unlike other DMA
operations. So we can't have dma_mapping_ops per device.
Note that POWER already has dma_mapping_ops per device but all the POWER
IOMMUs use the same dma_mapping_error function. x86 IOMMUs use device
argument.
[akpm@linux-foundation.org: fix sge]
[akpm@linux-foundation.org: fix svc_rdma]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix bnx2x]
[akpm@linux-foundation.org: fix s2io]
[akpm@linux-foundation.org: fix pasemi_mac]
[akpm@linux-foundation.org: fix sdhci]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix sparc]
[akpm@linux-foundation.org: fix ibmvscsi]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
spi_new_device() allocates and registers an spi device all in one swoop.
If the driver needs to add extra data to the spi_device before it is
registered, then this causes problems. This is needed for OF device
tree support so that the SPI device tree helper can add a pointer to
the device node after the device is allocated, but before the device
is registered. OF aware SPI devices can then retrieve data out of the
device node to populate a platform data structure.
This patch splits the allocation and registration portions of code out
of spi_new_device() and creates two new functions; spi_alloc_device()
and spi_register_device(). spi_new_device() is modified to use the new
functions for allocation and registration. None of the existing users
of spi_new_device() should be affected by this change.
Drivers using the new API can forego the use of spi_board_info
structure to describe the device layout and populate data into the
spi_device structure directly.
This change is in preparation for adding an OF device tree parser to
generate spi_devices based on data in the device tree.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Improve PIO transfer mode of au1550 spi controller by continuing of spi
transfer, instead of aborting transfer when transmit underflow interrupt
occurrs.
Verified by oscilloscope that the spi clock pauses on trasmit underflow,
so transfer continuation is perfectly valid even though au1550 datasheet
says that on tx underflow zeroes will be transfered.
Also make some error messages more specific.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the Au1550 resource table and instead extract MMIO/IRQ/DMA
resources from platform resource information like any well-behaved
platform driver.
Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Another step to removing ->ioctl and to removing the BKL
[dbrownell@users.sourceforge.net: take final step; BKL not needed]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, 'modalias' in the spi_device structure is a 'const char *'.
The spi_new_device() function fills in the modalias value from a passed in
spi_board_info data block. Since it is a pointer copy, the new spi_device
remains dependent on the spi_board_info structure after the new spi_device
is registered (no other fields in spi_device directly depend on the
spi_board_info structure; all of the other data is copied).
This causes a problem when dynamically propulating the list of attached
SPI devices. For example, in arch/powerpc, the list of SPI devices can be
populated from data in the device tree. With the current code, the device
tree adapter must kmalloc() a new spi_board_info structure for each new
SPI device it finds in the device tree, and there is no simple mechanism
in place for keeping track of these allocations.
This patch changes modalias from a 'const char *' to a fixed char array.
By copying the modalias string instead of referencing it, the dependency
on the spi_board_info structure is eliminated and an outside caller does
not need to maintain a separate spi_board_info allocation for each device.
If searched through the code to the best of my ability for any references
to modalias which may be affected by this change and haven't found
anything. It has been tested with the lite5200b platform in arch/powerpc.
[dbrownell@users.sourceforge.net: cope with linux-next changes: KOBJ_NAME_LEN obliterated, etc]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use "if SPI_MASTER" to remove numerous dependencies.
[dbrownell@users.sourceforge.net: remove a couple now-needless EXPERIMENTAL dependencies too]
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
xilinx_spi->irq is unsigned, so the test fails
Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Andrei Konovalov <akonovalov@ru.mvista.com>
Cc: Yuri Frolov <yfrolov@ru.mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This updates the SPI clock rate calculations for the spi_mpc83xx driver.
Some boundary conditions were wrong, and in several cases divide-by-16
wasn't always needed
Signed-off-by: Chen Gong <g.chen@freescale.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This mirrors the functionality that driver_find_device has as well.
We add a start variable, and all callers of the function are fixed up at
the same time.
The block layer will be using this new functionality in a follow-on
patch.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Switch over to use the shiny new device_create_drvdata() call
instead of the original device_create() calls, so this continues
to work after device_create() is removed.
Note that this driver never had the race which motivated removing
the original call; it locked correctly.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (241 commits)
[ARM] 5171/1: ep93xx: fix compilation of modules using clocks
[ARM] 5133/2: at91sam9g20 defconfig file
[ARM] 5130/4: Support for the at91sam9g20
[ARM] 5160/1: IOP3XX: gpio/gpiolib support
[ARM] at91: Fix NAND FLASH timings for at91sam9x evaluation kits.
[ARM] 5084/1: zylonite: Register AC97 device
[ARM] 5085/2: PXA: Move AC97 over to the new central device declaration model
[ARM] 5120/1: pxa: correct platform driver names for PXA25x and PXA27x UDC drivers
[ARM] 5147/1: pxaficp_ir: drop pxa_gpio_mode calls, as pin setting
[ARM] 5145/1: PXA2xx: provide api to control IrDA pins state
[ARM] 5144/1: pxaficp_ir: cleanup includes
[ARM] pxa: remove pxa_set_cken()
[ARM] pxa: allow clk aliases
[ARM] Feroceon: don't disable BPU on boot
[ARM] Orion: LED support for HP mv2120
[ARM] Orion: add RD88F5181L-FXO support
[ARM] Orion: add RD88F5181L-GE support
[ARM] Orion: add Netgear WNR854T support
[ARM] s3c2410_defconfig: update for current build
[ARM] Acer n30: Minor style and indentation fixes.
...
This got broken by the recent "fix rmmod $spi_driver while spidev-user is
active". I tested the rmmod & write path but didn't check the read path.
I am sorry. The read logic changed and spidev_sync_read() +
spidev_sync_write() do not return zero on success anymore but the number
of bytes that has been transfered over the bus. This patch changes the
logic and copy_to_user() gets called again.
The write path returns the number of bytes which are written to the
underlying device what may be less than the requested size. This patch
makes the same change to the read path or else we request a read of 20
bytes, get 10, don't call copy to user and report to the user that we read
10 bytes.
[akpm@linux-foundation.org: remove test of known-to-be-zero local]
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
imx_dma_request_by_prio can return channel number by itself.
No need to supply variable address through parameters.
Also converted all drivers using this function.
Signed-off-by: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This addresses other oopsing paths in "spidev" by changing how it manages
refcounting. It decouples the lifecycle of the per-device data from the
class device (not just the spi device):
- Use class_{create,destroy} not class_{register,unregister}.
- Use device_{create,destroy} not device_{register,unregister}.
- Free the per-device data only when TWO conditions are true:
* Driver is unbound from underlying SPI device, and
* Device is no longer open (new)
Also, spi_{get,set}_drvdata not dev_{get,set}_drvdata for simpler code.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Sebastian Siewior <bigeasy@tglx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Somehow the spidev code forgot to include a critical mechanism: when the
underlying device is removed (e.g. spi_master rmmod), open file
descriptors must be prevented from issuing new I/O requests to that
device. On penalty of the oopsing reported by Sebastian Siewior
<bigeasy@tglx.de> ...
This is a partial fix, adding handshaking between the lower level (SPI
messaging) and the file operations using the spi_dev. (It also fixes an
issue where reads and writes didn't return the number of bytes sent or
received.)
There's still a refcounting issue to be addressed (separately).
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Reported-by: Sebastian Siewior <bigeasy@tglx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current driver may cause glitches on SPI CLK line since one must disable
the SPI controller before changing any HW settings. Fix this by implementing
a local spi_transfer function that won't change speed and/or word size while
CS is active.
While doing that heavy lifting a few other issues were addressed too:
- Make word size 16 and 32 work too.
- Honor bits_per_word and speed_hz in spi transaction.
- Optimize the common path.
This also stops using the "bitbang" framework (except for a few constants).
[Roel Kluin <12o3l@tiscali.nl>: "irq" needs to be signed]
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a typo in pxa2xx_spi.c, comment says "Enable the SSP clock", code
says: clk_disable ... so after resume, the SSP is dead.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ned Forrester <nforrester@whoi.edu>
Cc: Stephen Street <stephen@streetfiresound.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On Fri, Apr 18, 2008 at 09:08:55PM +0200, Julia Lawall wrote:
> I found 63 occurrences of this problem with the following semantic match
> (http://www.emn.fr/x-info/coccinelle/):
>
> @@ unsigned int i; @@
>
> * i < 0
>
Since this one's always in the range 0-255, it could probably be made
signed, but it's just as easy to make it work unsigned.
Reported-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use PIO for full-duplex transfers, instead of DMA.
Signed-off-by: Vitja Makarov <vitja.makarov@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the baud rate divisor calculation code a bit more readable and add a
few comments.
Also fix wrong debug information being displayed when !new_1 and
max_speed_hz == 0.
[david-b@pacbell.net: fix it]
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Cc: "Janesh Ramakrishnan" <jramakrishnan@neuropace.com>
Acked-by David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Updates to the i.MX SPI controller driver:
1) Some comments changed and/or added.
2) End of transfers is now managed on TXFIFO empty interrupt after the
last write to TXFIFO. This speeds interrupt execution by removing
the wait for TXFIFO to become empty. On TXFIFO empty interrupt the
handler needs only to poll for the end of the ongoing transaction
(SPI_CONTROL_XCH) to close the transfer.
(2.1) Write only transfers are closed flushing RXFIFO.
(2.2) Read transfers are closed reading trailing bytes from RXFIFO.
(2.3) Read transfers where RXFIFO overrun occurred are closed by
flushing RXFIFO and aborting the message.
3) Fifos are now flushed via SPI disable after the end of ongoing
transaction.
Signed-off-by: Andrea Paterniani <a.paterniani@swapp-eng.it>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A spi transfer with zero length is not invalid. For example, such
transfer (len == 0 && delay_usecs != 0) can be used to achieve delay
before first CLK edge after chipselect assertion.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Various cleanups to pxa2xx_spi suggested by "sparse": make sure that
register addresess are "void __iomem *", and make a few functions properly
static.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ned Forrester <nforrester@whoi.edu>
Cc: Stephen Street <stephen@streetfiresound.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The SPI core now expects num_chipselect to be set correctly as due to added
checks on the chip being selected before an transfer is allowed. This patch
adds a num_cs field to the platform data which needs to be set correctly
before adding the SPI platform device.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass the bus number we expect the S3C24XX SPI driver to attach to via the
platform data.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The s3c24xx_spi_txrx() function should initialise the completion each time
before using it, otherwise we end up with the possibility of returning success
before the interrupt handler has processed all the data.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since 43cc71eed1, the platform modalias is
prefixed with "platform:". Add MODULE_ALIAS() to the hotpluggable SPI
platform drivers, to allow module auto loading.
[dbrownell@users.sourceforge.net: more drivers: registration fixes]
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix bug in SPI probe: first initialize peripheral pins, and just after
register spi master device. This fixes problems with SPI drivers built-in
kernel.
Singed-off-by: Vitja Makarov <vitja.makarov@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix breakage cause by overzealous line wrapping; there should be only one
format string.
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SPI controller drivers return number of bytes actually transfered from
bitbang->txrx_bufs() method. This updates handling of short transfers (where
the transfer size is less than requested):
- Even zero byte short transfers should report errors;
- Include short transfers in the total of transferred bytes;
- Use EREMOTEIO (like USB) not EMSGSIZE to report short transfers
Short transfers don't normally mean invalid message sizes, but if the
underlying controller driver needs to use EMSGSIZE it can still do so.
[db: fix two more minor issues]
Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove struct pt_regs *regs from prototype of au1550_spi_irq handler to avoid
warning in request_irq(). Also fix comment type leadin.
Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit id 94f389485e (Separate MPC52xx PSC FIOF
regsiters from the rest of PSC) split the PSC fifo registers away from the
core PSC regs. Doing so broke the mpc52xx_psc_spi driver.
This patch teaches the mpc52xx_psc_spi driver about the new PSC fifo
register definitions.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: David Brownell <david-b@pacbell.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@gate.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes a sequencing bug in spi driver pxa2xx_spi.c in which the chip select
for a transfer may be asserted before the clock polarity is set on the
interface. As a result of this bug, the clock signal may have the wrong
polarity at transfer start, so it may need to make an extra half transition
before the intended clock/data signals begin. (This probably means all
transfers are one bit out of sequence.)
This only occurs on the first transfer following a change in clock polarity
in systems using more than one more than one such polarity. The fix
assures that the clock mode is properly set before asserting chip select.
This bug was introduced in a patch merged on 2006/12/10, kernel 2.6.20.
The patch defines an additional bit in: include/asm-arm/arch-pxa/regs-ssp.h
for 2.6.25 and newer kernels but this addition must be made in:
include/asm-arm/arch-pxa/pxa-regs.h for kernels between 2.6.20 and 2.6.24,
inclusive
Signed-off-by: Ned Forrester <nforrester@whoi.edu>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The atmel_spi driver does not initialize clock polarity correctly (except for
at91rm9200 CS0 channel) in some case.
The atmel_spi driver uses gpio-controlled chipselect. OTOH spi clock signal
is controlled by CSRn.CPOL bit, but this register controls clock signal
correctly only in 'real transfer' duration. At the time of cs_activate()
call, CSRn.CPOL will be initialized correctly, but the controller do not know
which channel is to be used next, so clock signal will stay at the inactive
state of last transfer. If clock polarity of new transfer and last transfer
was differ, new transfer will start with wrong clock signal state.
For example, if you started SPI MODE 2 or 3 transfer after SPI MODE 0 or 1
transfer, the clock signal state at the assertion of chipselect will be low.
Of course this will violates SPI transfer.
This patch is short term solution for this problem. It makes all CSRn.CPOL
match for the transfer before activating chipselect. For longer term, the
best fix might be to let NPCS0 stay selected permanently in MR and overwrite
CSR0 with to the new slave's settings before asserting CS.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove some more references to dev->power.power_state. That field is overdue
for removal, but we can't do that while it's still referenced in the kernel.
The only reason to update it was to make the /sys/devices/.../power/state
files (now removed) work better.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
