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/mpc52xx_psc_spi.c b/drivers/spi/mpc52xx_psc_spi.c
index 11f36bef3057..d2a4b2bdb07b 100644
--- a/drivers/spi/mpc52xx_psc_spi.c
+++ b/drivers/spi/mpc52xx_psc_spi.c
@@ -270,6 +270,9 @@ static void mpc52xx_psc_spi_work(struct work_struct *work)
         spin_unlock_irq(&mps->lock);
 }
 
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST)
+
 static int mpc52xx_psc_spi_setup(struct spi_device *spi)
 {
         struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
@@ -279,6 +282,12 @@ static int mpc52xx_psc_spi_setup(struct spi_device *spi)
         if (spi->bits_per_word%8)
                 return -EINVAL;
 
+        if (spi->mode & ~MODEBITS) {
+                dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+                        spi->mode & ~MODEBITS);
+                return -EINVAL;
+        }
+
         if (!cs) {
                 cs = kzalloc(sizeof *cs, GFP_KERNEL);
                 if (!cs)