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>
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>
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>
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>
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>
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>
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>
