iio: accel: st_accel: add SPI-3wire support

Add SPI Serial Interface Mode (SIM) register information
in st_sensor_settings look up table to support devices
(like LSM303AGR accel sensor) that allow just SPI-3wire
communication mode. SIM mode has to be configured before any
other operation since it is not enabled by default and the driver
is not able to read without that configuration

Whilst a fairly substantial patch, the actual logic is simple and it
is better to have the generic fix than a band aid.

Fixes: ddc05fa28606 (iio: st-accel: add support for lsm303agr accel)
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
index 497f2b3a5a62..97f1b465d04f 100644
--- a/include/linux/iio/common/st_sensors.h
+++ b/include/linux/iio/common/st_sensors.h
@@ -105,6 +105,11 @@ struct st_sensor_fullscale {
 	struct st_sensor_fullscale_avl fs_avl[ST_SENSORS_FULLSCALE_AVL_MAX];
 };
 
+struct st_sensor_sim {
+	u8 addr;
+	u8 value;
+};
+
 /**
  * struct st_sensor_bdu - ST sensor device block data update
  * @addr: address of the register.
@@ -197,6 +202,7 @@ struct st_sensor_transfer_function {
  * @bdu: Block data update register.
  * @das: Data Alignment Selection register.
  * @drdy_irq: Data ready register of the sensor.
+ * @sim: SPI serial interface mode register of the sensor.
  * @multi_read_bit: Use or not particular bit for [I2C/SPI] multi-read.
  * @bootime: samples to discard when sensor passing from power-down to power-up.
  */
@@ -213,6 +219,7 @@ struct st_sensor_settings {
 	struct st_sensor_bdu bdu;
 	struct st_sensor_das das;
 	struct st_sensor_data_ready_irq drdy_irq;
+	struct st_sensor_sim sim;
 	bool multi_read_bit;
 	unsigned int bootime;
 };