2 files changed, 14 insertions, 3 deletions

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 38b60ad0eda0..630f781aeb19 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -55,9 +55,16 @@
 static unsigned long    minors[N_SPI_MINORS / BITS_PER_LONG];
 
 
-/* Bit masks for spi_device.mode management */
-#define SPI_MODE_MASK                   (SPI_CPHA | SPI_CPOL)
-
+/* Bit masks for spi_device.mode management.  Note that incorrect
+ * settings for CS_HIGH and 3WIRE can cause *lots* of trouble for other
+ * devices on a shared bus:  CS_HIGH, because this device will be
+ * active when it shouldn't be;  3WIRE, because when active it won't
+ * behave as it should.
+ *
+ * REVISIT should changing those two modes be privileged?
+ */
+#define SPI_MODE_MASK           (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
+                                | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP)
 
 struct spidev_data {
         struct device           dev;
diff --git a/include/linux/spi/spidev.h b/include/linux/spi/spidev.h
index 7d700be57490..c93ef9d42a01 100644
--- a/include/linux/spi/spidev.h
+++ b/include/linux/spi/spidev.h
@@ -35,6 +35,10 @@
 #define SPI_MODE_2              (SPI_CPOL|0)
 #define SPI_MODE_3              (SPI_CPOL|SPI_CPHA)
 
+#define SPI_CS_HIGH             0x04
+#define SPI_LSB_FIRST           0x08
+#define SPI_3WIRE               0x10
+#define SPI_LOOP                0x20
 
 /*---------------------------------------------------------------------------*/