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author | David Brownell <dbrownell@users.sourceforge.net> | 2009-09-22 16:46:18 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 07:39:44 -0700 |
commit | 568d0697f42771425ae9f1e9a3db769fef7e10b6 (patch) | |
tree | 8f4d1178b88481e3d3daba3e049c700a3cef72e4 /include/linux | |
parent | 7869c0b9ed44404bbc675ef76f8ccb3be5496f39 (diff) | |
download | op-kernel-dev-568d0697f42771425ae9f1e9a3db769fef7e10b6.zip op-kernel-dev-568d0697f42771425ae9f1e9a3db769fef7e10b6.tar.gz |
spi: handle TX-only/RX-only
Support two new half-duplex SPI implementation restrictions, for links
that talk to TX-only or RX-only devices. (Existing half-duplex flavors
support both transfer directions, just not at the same time.)
Move spi_async() into the spi.c core, and stop inlining it. Then make
that function perform error checks and reject messages that demand more
than the underlying controller can support.
Based on a patch from Marek Szyprowski which did this only for the
bitbanged GPIO driver.
Cc: Marek Szyprowski <m.szyprowski@samsung.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>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/spi/spi.h | 39 |
1 files changed, 3 insertions, 36 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index e2051f3..97b60b3 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -258,6 +258,8 @@ struct spi_master { /* other constraints relevant to this driver */ u16 flags; #define SPI_MASTER_HALF_DUPLEX BIT(0) /* can't do full duplex */ +#define SPI_MASTER_NO_RX BIT(1) /* can't do buffer read */ +#define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */ /* Setup mode and clock, etc (spi driver may call many times). * @@ -538,42 +540,7 @@ static inline void spi_message_free(struct spi_message *m) } extern int spi_setup(struct spi_device *spi); - -/** - * spi_async - asynchronous SPI transfer - * @spi: device with which data will be exchanged - * @message: describes the data transfers, including completion callback - * Context: any (irqs may be blocked, etc) - * - * This call may be used in_irq and other contexts which can't sleep, - * as well as from task contexts which can sleep. - * - * The completion callback is invoked in a context which can't sleep. - * Before that invocation, the value of message->status is undefined. - * When the callback is issued, message->status holds either zero (to - * indicate complete success) or a negative error code. After that - * callback returns, the driver which issued the transfer request may - * deallocate the associated memory; it's no longer in use by any SPI - * core or controller driver code. - * - * Note that although all messages to a spi_device are handled in - * FIFO order, messages may go to different devices in other orders. - * Some device might be higher priority, or have various "hard" access - * time requirements, for example. - * - * On detection of any fault during the transfer, processing of - * the entire message is aborted, and the device is deselected. - * Until returning from the associated message completion callback, - * no other spi_message queued to that device will be processed. - * (This rule applies equally to all the synchronous transfer calls, - * which are wrappers around this core asynchronous primitive.) - */ -static inline int -spi_async(struct spi_device *spi, struct spi_message *message) -{ - message->spi = spi; - return spi->master->transfer(spi, message); -} +extern int spi_async(struct spi_device *spi, struct spi_message *message); /*---------------------------------------------------------------------------*/ |