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, 15 deletions

diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c
index 656be4a5094a..aee9ad6f633c 100644
--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -1163,6 +1163,9 @@ msg_rejected:
         return -EINVAL;
 }
 
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
+
 /* On first setup bad values must free chip_data memory since will cause
    spi_new_device to fail. Bad value setup from protocol driver are simply not
    applied and notified to the calling driver. */
@@ -1174,6 +1177,12 @@ static int setup(struct spi_device *spi)
         u32 tmp;
         int status = 0;
 
+        if (spi->mode & ~MODEBITS) {
+                dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+                        spi->mode & ~MODEBITS);
+                return -EINVAL;
+        }
+
         /* Get controller data */
         chip_info = spi->controller_data;
 
@@ -1245,21 +1254,6 @@ static int setup(struct spi_device *spi)
 
         /* SPI mode */
         tmp = spi->mode;
-        if (tmp & SPI_LSB_FIRST) {
-                status = -EINVAL;
-                if (first_setup) {
-                        dev_err(&spi->dev,
-                                "setup - "
-                                "HW doesn't support LSB first transfer\n");
-                        goto err_first_setup;
-                } else {
-                        dev_err(&spi->dev,
-                                "setup - "
-                                "HW doesn't support LSB first transfer, "
-                                "default to MSB first\n");
-                        spi->mode &= ~SPI_LSB_FIRST;
-                }
-        }
         if (tmp & SPI_CS_HIGH) {
                 u32_EDIT(chip->control,
                                 SPI_CONTROL_SSPOL, SPI_CONTROL_SSPOL_ACT_HIGH);