From: Michal Suchanek
On some SPI controllers it is not feasible to transfer arbitrary amount
of data at once.
When the limit on transfer size is a few kilobytes at least it makes
sense to use the SPI hardware rather than reverting to gpio driver.
The protocol drivers need a way to check that they do not sent overly
long messages, though.
Signed-off-by: Michal Suchanek
Signed-off-by: Mark Brown
Git-commit: 4acad4aae10d1fa79a075b38b5c73772c44f576c
Patch-mainline: v4.5-rc1
Signed-off-by: Matwey V. Kornilov
---
include/linux/spi/spi.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index cce80e6dc7d1..3eebc6c235fb 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -425,6 +425,12 @@ struct spi_master {
#define SPI_MASTER_MUST_RX BIT(3) /* requires rx */
#define SPI_MASTER_MUST_TX BIT(4) /* requires tx */
+ /*
+ * on some hardware transfer size may be constrained
+ * the limit may depend on device transfer settings
+ */
+ size_t (*max_transfer_size)(struct spi_device *spi);
+
/* lock and mutex for SPI bus locking */
spinlock_t bus_lock_spinlock;
struct mutex bus_lock_mutex;
@@ -832,6 +838,15 @@ extern int spi_async(struct spi_device *spi, struct spi_message *message);
extern int spi_async_locked(struct spi_device *spi,
struct spi_message *message);
+static inline size_t
+spi_max_transfer_size(struct spi_device *spi)
+{
+ struct spi_master *master = spi->master;
+ if (!master->max_transfer_size)
+ return SIZE_MAX;
+ return master->max_transfer_size(spi);
+}
+
/*---------------------------------------------------------------------------*/
/* All these synchronous SPI transfer routines are utilities layered
--
2.12.0
--
To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org
To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org
