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Commit 543bb255 authored by Stephen Warren's avatar Stephen Warren Committed by Mark Brown
Browse files

spi: add ability to validate xfer->bits_per_word in SPI core 



Allow SPI masters to define the set of bits_per_word values they support.
If they do this, then the SPI core will reject transfers that attempt to
use an unsupported bits_per_word value. This eliminates the need for each
SPI driver to implement this checking in most cases.

Signed-off-by: default avatarStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 5c725b34

drivers/spi/spi.c

+8 −0
Original line number Diff line number Diff line
@@ -1377,6 +1377,14 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message) 
			xfer->bits_per_word = spi->bits_per_word;

		if (!xfer->speed_hz)

			xfer->speed_hz = spi->max_speed_hz;

		if (master->bits_per_word_mask) {

			/* Only 32 bits fit in the mask */

			if (xfer->bits_per_word > 32)

				return -EINVAL;

			if (!(master->bits_per_word_mask &

					BIT(xfer->bits_per_word - 1)))

				return -EINVAL;

		}

	}



	message->spi = spi;

include/linux/spi/spi.h

+8 −0
Original line number Diff line number Diff line
@@ -228,6 +228,11 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) 
 *	every chipselect is connected to a slave.

 * @dma_alignment: SPI controller constraint on DMA buffers alignment.

 * @mode_bits: flags understood by this controller driver

 * @bits_per_word_mask: A mask indicating which values of bits_per_word are

 *	supported by the driver. Bit n indicates that a bits_per_word n+1 is

 *	suported. If set, the SPI core will reject any transfer with an

 *	unsupported bits_per_word. If not set, this value is simply ignored,

 *	and it's up to the individual driver to perform any validation.

 * @flags: other constraints relevant to this driver

 * @bus_lock_spinlock: spinlock for SPI bus locking

 * @bus_lock_mutex: mutex for SPI bus locking
@@ -301,6 +306,9 @@ struct spi_master { 
	/* spi_device.mode flags understood by this controller driver */

	u16			mode_bits;



	/* bitmask of supported bits_per_word for transfers */

	u32			bits_per_word_mask;



	/* other constraints relevant to this driver */

	u16			flags;

#define SPI_MASTER_HALF_DUPLEX	BIT(0)		/* can't do full duplex */