2 files changed, 5 insertions, 0 deletions

diff --git a/drivers/hwmon/lm70.c b/drivers/hwmon/lm70.c
index 7eaae3834e15..275d392eca61 100644
--- a/drivers/hwmon/lm70.c
+++ b/drivers/hwmon/lm70.c
@@ -96,6 +96,10 @@ static int __devinit lm70_probe(struct spi_device *spi)
         struct lm70 *p_lm70;
         int status;
 
+        /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
+        if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
+                return -EINVAL;
+
         p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
         if (!p_lm70)
                 return -ENOMEM;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 1be5ea059477..302b81d1d117 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -76,6 +76,7 @@ struct spi_device {
 #define SPI_MODE_3      (SPI_CPOL|SPI_CPHA)
 #define SPI_CS_HIGH     0x04                    /* chipselect active high? */
 #define SPI_LSB_FIRST   0x08                    /* per-word bits-on-wire */
+#define SPI_3WIRE       0x10                    /* SI/SO signals shared */
         u8                      bits_per_word;
         int                     irq;
         void                    *controller_state;