@@ -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
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 <hramrach@gmail.com> --- - return SIZE_MAX when no limit is known --- include/linux/spi/spi.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)