spi: move more spi_setup() functionality into core

Move some common spi_setup() error checks into the SPI framework from the
spi_master controller drivers:

 - Add a new "mode_bits" field to spi_master

 - Use that in spi_setup to validate the spi->mode value being
   requested.  Setting this new field is now mandatory for any
   controller supporting more than vanilla SPI_MODE_0.

 - Update all spi_master drivers to:

     * Initialize that field
     * Remove current spi_setup() checks using that value.

This is a net minor code shrink.

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, 11 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0276bc37e255..a525a3a848c1 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -607,8 +607,19 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
  */
 int spi_setup(struct spi_device *spi)
 {
+        unsigned        bad_bits;
         int             status;
 
+        /* help drivers fail *cleanly* when they need options
+         * that aren't supported with their current master
+         */
+        bad_bits = spi->mode & ~spi->master->mode_bits;
+        if (bad_bits) {
+                dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+                        bad_bits);
+                return -EINVAL;
+        }
+
         if (!spi->bits_per_word)
                 spi->bits_per_word = 8;