From: David Brownell Add a new spi->mode bit: SPI_3WIRE, for chips where the SI and SO signals are shared (and which are thus only half duplex). Update the LM70 driver to require support for that hardware mode from the controller. Signed-off-by: David Brownell Signed-off-by: Andrew Morton --- drivers/hwmon/lm70.c | 4 ++++ include/linux/spi/spi.h | 1 + 2 files changed, 5 insertions(+) diff -puN drivers/hwmon/lm70.c~spi-add-3wire-mode-flag drivers/hwmon/lm70.c --- a/drivers/hwmon/lm70.c~spi-add-3wire-mode-flag +++ a/drivers/hwmon/lm70.c @@ -96,6 +96,10 @@ static int __devinit lm70_probe(struct s 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 -puN include/linux/spi/spi.h~spi-add-3wire-mode-flag include/linux/spi/spi.h --- a/include/linux/spi/spi.h~spi-add-3wire-mode-flag +++ a/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; _