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, 7 insertions, 1 deletions

diff --git a/drivers/spi/spi_s3c24xx.c b/drivers/spi/spi_s3c24xx.c
index d5a710f6e445..7071ff8da63e 100644
--- a/drivers/spi/spi_s3c24xx.c
+++ b/drivers/spi/spi_s3c24xx.c
@@ -146,6 +146,9 @@ static int s3c24xx_spi_setupxfer(struct spi_device *spi,
         return 0;
 }
 
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
+
 static int s3c24xx_spi_setup(struct spi_device *spi)
 {
         int ret;
@@ -153,8 +156,11 @@ static int s3c24xx_spi_setup(struct spi_device *spi)
         if (!spi->bits_per_word)
                 spi->bits_per_word = 8;
 
-        if ((spi->mode & SPI_LSB_FIRST) != 0)
+        if (spi->mode & ~MODEBITS) {
+                dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+                        spi->mode & ~MODEBITS);
                 return -EINVAL;
+        }
 
         ret = s3c24xx_spi_setupxfer(spi, NULL);
         if (ret < 0) {