According to the AD7877 datasheet:

Each transfer operation is 16-bit. If multiple read/write operations are
to be performed, CS must be taken high after the end of each read/write
operation before another read/write operation can be performed by
taking CS low again.

Make sure CS toggles after each transfer in the message.
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

With no word size given in the users platform data, a generic spi host
controller driver will assume a default word size of eight bit. This
causes transmission to be performed bytewise, which will fail on little
endian machines for sure. Failure on big endian depends on usage
of slave select to mark word boundaries.

Anyway, ad7877 is specified to work with 16 bit per word, so
unconditionally set the word size accordingly. Flag an error where 16
bit per word is not available.
Signed-off-by: NOskar Schirmer <os@emlix.com>
Signed-off-by: NDaniel Glöckner <dg@emlix.com>
Signed-off-by: NOliver Schneidewind <osw@emlix.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

With dma based spi transmission, data corruption is observed
occasionally. With dma buffers located right next to msg and
xfer fields, cache lines correctly flushed in preparation for
dma usage may be polluted again when writing to fields in the
same cache line.

Make sure cache fields used with dma do not share cache lines
with fields changed during dma handling. As both fields are part
of a struct that is allocated via kzalloc, thus cache aligned,
moving the fields to the 1st position and insert padding for
alignment does the job.
Signed-off-by: NOskar Schirmer <os@emlix.com>
Signed-off-by: NDaniel Glöckner <dg@emlix.com>
Signed-off-by: NOliver Schneidewind <osw@emlix.com>
Signed-off-by: NJohannes Weiner <jw@emlix.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
[dtor@mail.ru - changed to use ___cacheline_aligned as suggested
 by akpm]
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

The time interval between consecutive interrupts depends on a number of
tunables: first_conversion_delay, acquisition_time, averaging and foremost
the pen_down_acc_interval.

Since the mod_timer() action for the PEN UP event happens in the
spi_async() callback function, latencies incurred by the spi bus drivers
also need to be taken into account.

So all in all, give the PEN UP event a bit more wiggle room and increase
timeout to 100ms.
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

This makes it consistent with other buses (platform, i2c, vio, ...).  I'm
not sure why we use the prefixes, but there must be a reason.

This was easy enough to do it, and I did it.
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Samuel Ortiz <sameo@openedhand.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Acked-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch removes depreciated IRQF_SAMPLE_RANDOM flags from
ad7877 and ad7879 touchscreen drivers.
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

[dtor@mail.ru: locking and other fixups]
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>