SPI controller drivers: check for unsupported modes

Minor SPI controller driver updates: make the setup() methods reject
spi->mode bits they don't support, by masking aginst the inverse of bits
they *do* support.  This insures against misbehavior later when new mode
bits get added.

Most controllers can't support SPI_LSB_FIRST; more handle SPI_CS_HIGH.
Support for all four SPI clock/transfer modes is routine.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
index 9f2c887ffa04..e51311b2da0b 100644
--- a/drivers/spi/pxa2xx_spi.c
+++ b/drivers/spi/pxa2xx_spi.c
@@ -1067,6 +1067,9 @@ static int transfer(struct spi_device *spi, struct spi_message *msg)
         return 0;
 }
 
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA)
+
 static int setup(struct spi_device *spi)
 {
         struct pxa2xx_spi_chip *chip_info = NULL;
@@ -1093,6 +1096,12 @@ static int setup(struct spi_device *spi)
                 return -EINVAL;
         }
 
+        if (spi->mode & ~MODEBITS) {
+                dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+                        spi->mode & ~MODEBITS);
+                return -EINVAL;
+        }
+
         /* Only alloc on first setup */
         chip = spi_get_ctldata(spi);
         if (!chip) {