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: Stephen Warren <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 38c2b92..733eb5e 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -228,6 +228,11 @@
* 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 @@
/* 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 */
