iio: st_sensors: verify interrupt event to status

This makes all ST sensor drivers check that they actually have
new data available for the requested channel(s) before claiming
an IRQ, by reading the status register (which is conveniently
the same for all ST sensors) and check that the channel has new
data before proceeding to read it and fill the buffer.

This way sensors can share an interrupt line: it can be flaged
as shared and then the sensor that did not fire will return
NO_IRQ, and the sensor that fired will handle the IRQ and
return IRQ_HANDLED.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
index 6670c3d25c58..d8da075bfda0 100644
--- a/include/linux/iio/common/st_sensors.h
+++ b/include/linux/iio/common/st_sensors.h
@@ -37,6 +37,7 @@
 #define ST_SENSORS_DEFAULT_AXIS_ADDR            0x20
 #define ST_SENSORS_DEFAULT_AXIS_MASK            0x07
 #define ST_SENSORS_DEFAULT_AXIS_N_BIT           3
+#define ST_SENSORS_DEFAULT_STAT_ADDR            0x27
 
 #define ST_SENSORS_MAX_NAME                     17
 #define ST_SENSORS_MAX_4WAI                     7
@@ -121,6 +122,7 @@ struct st_sensor_bdu {
  * @mask_int2: mask to enable/disable IRQ on INT2 pin.
  * @addr_ihl: address to enable/disable active low on the INT lines.
  * @mask_ihl: mask to enable/disable active low on the INT lines.
+ * @addr_stat_drdy: address to read status of DRDY (data ready) interrupt
  * struct ig1 - represents the Interrupt Generator 1 of sensors.
  * @en_addr: address of the enable ig1 register.
  * @en_mask: mask to write the on/off value for enable.
@@ -131,6 +133,7 @@ struct st_sensor_data_ready_irq {
         u8 mask_int2;
         u8 addr_ihl;
         u8 mask_ihl;
+        u8 addr_stat_drdy;
         struct {
                 u8 en_addr;
                 u8 en_mask;