spi: check bits_per_word in spi_setup

This allows drivers for devices connected via SPI to check if the
controller supports a given bits_per_word value during setup.
Currently any BPW value is accepted durings setup, and transfers
are rejected later.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 637d892b316de6dceb8663eb47ad3887491830a6..829323ce7cdfb39d526add7cdeb0aadeda8e3b4c 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1740,6 +1740,20 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
  * other core methods are currently defined as inline functions.
  */
 
+static int __spi_validate_bits_per_word(struct spi_master *master, u8 bits_per_word)
+{
+       if (master->bits_per_word_mask) {
+               /* Only 32 bits fit in the mask */
+               if (bits_per_word > 32)
+                       return -EINVAL;
+               if (!(master->bits_per_word_mask &
+                               SPI_BPW_MASK(bits_per_word)))
+                       return -EINVAL;
+       }
+
+       return 0;
+}
+
 /**
  * spi_setup - setup SPI mode and clock rate
  * @spi: the device whose settings are being modified
@@ -1798,6 +1812,9 @@ int spi_setup(struct spi_device *spi)
        if (!spi->bits_per_word)
                spi->bits_per_word = 8;
 
+       if (__spi_validate_bits_per_word(spi->master, spi->bits_per_word))
+               return -EINVAL;
+
        if (!spi->max_speed_hz)
                spi->max_speed_hz = spi->master->max_speed_hz;
 
@@ -1867,14 +1884,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
                    xfer->speed_hz > master->max_speed_hz)
                        xfer->speed_hz = master->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;
-               }
+               if (__spi_validate_bits_per_word(master, xfer->bits_per_word))
+                       return -EINVAL;
 
                /*
                 * SPI transfer length should be multiple of SPI word size