iio: imu: st_lsm6dsx: support active-low interrupts

Add support for active low interrupts (IRQF_TRIGGER_LOW and
IRQF_TRIGGER_FALLING). Configure the device as active high or low
according to the requested irq line.

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c

@@ -37,6 +37,8 @@
 #define ST_LSM6DSX_REG_FIFO_THH_ADDR 0x07
 #define ST_LSM6DSX_FIFO_TH_MASK GENMASK(11, 0)
 #define ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR 0x08
+#define ST_LSM6DSX_REG_HLACTIVE_ADDR 0x12
+#define ST_LSM6DSX_REG_HLACTIVE_MASK BIT(5)
 #define ST_LSM6DSX_REG_FIFO_MODE_ADDR 0x0a
 #define ST_LSM6DSX_FIFO_MODE_MASK GENMASK(2, 0)
 #define ST_LSM6DSX_FIFO_ODR_MASK GENMASK(6, 3)
@@ -417,19 +419,31 @@ int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw)
 {
  struct iio_buffer *buffer;
  unsigned long irq_type;
+ bool irq_active_low;
  int i, err;
 
  irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));
 
  switch (irq_type) {
  case IRQF_TRIGGER_HIGH:
  case IRQF_TRIGGER_RISING:
+ irq_active_low = false;
+ break;
+ case IRQF_TRIGGER_LOW:
+ case IRQF_TRIGGER_FALLING:
+ irq_active_low = true;
  break;
  default:
  dev_info(hw->dev, "mode %lx unsupported\n", irq_type);
  return -EINVAL;
  }
 
+ err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_HLACTIVE_ADDR,
+ ST_LSM6DSX_REG_HLACTIVE_MASK,
+ irq_active_low);
+ if (err < 0)
+ return err;
+
  err = devm_request_threaded_irq(hw->dev, hw->irq,
  st_lsm6dsx_handler_irq,
  st_lsm6dsx_handler_thread,