spi: Support transfer speed checking in the core

Allow drivers to avoid implementing their own checks for simple rates by
specifying the limits in the master structure.

Signed-off-by: Mark Brown <broonie@linaro.org>

2 files changed, 13 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 978dda2c5239..a52f16685d6a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1387,6 +1387,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
                                         BIT(xfer->bits_per_word - 1)))
                                 return -EINVAL;
                 }
+
+                if (xfer->speed_hz && master->min_speed_hz &&
+                    xfer->speed_hz < master->min_speed_hz)
+                        return -EINVAL;
+                if (xfer->speed_hz && master->max_speed_hz &&
+                    xfer->speed_hz > master->max_speed_hz)
+                        return -EINVAL;
         }
 
         message->spi = spi;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 28e440be1c07..cdf668156154 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -233,6 +233,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  *      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.
+ * @min_speed_hz: Lowest supported transfer speed
+ * @max_speed_hz: Highest supported transfer speed
  * @flags: other constraints relevant to this driver
  * @bus_lock_spinlock: spinlock for SPI bus locking
  * @bus_lock_mutex: mutex for SPI bus locking
@@ -312,6 +314,10 @@ struct spi_master {
 #define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0UL : (BIT(bits) - 1))
 #define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
 
+        /* limits on transfer speed */
+        u32                     min_speed_hz;
+        u32                     max_speed_hz;
+
         /* other constraints relevant to this driver */
         u16                     flags;
 #define SPI_MASTER_HALF_DUPLEX  BIT(0)          /* can't do full duplex */