iio: cros_ec: Expose hwfifo_timeout

Expose EC minimal interrupt period through buffer/hwfifo_timeout:
- Maximal timeout is limited to 65s.
- When timeout for all sensors is set to 0, EC will not send events,
  even if the sensor sampling rate is greater than 0.

Rename frequency to sampling_frequency to match IIO ABI.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

include/linux/iio/common/cros_ec_sensors_core.h

@@ -50,7 +50,6 @@ typedef irqreturn_t (*cros_ec_sensors_capture_t)(int irq, void *p);
  *				the timestamp. The timestamp is always last and
  *				is always 8-byte aligned.
  * @read_ec_sensors_data:	function used for accessing sensors values
- * @cuur_sampl_freq:		current sampling period
  */
 struct cros_ec_sensors_core_state {
 	struct cros_ec_device *ec;
@@ -73,8 +72,6 @@ struct cros_ec_sensors_core_state {
 	int (*read_ec_sensors_data)(struct iio_dev *indio_dev,
 				    unsigned long scan_mask, s16 *data);
 
-	int curr_sampl_freq;
-
 	/* Table of known available frequencies : 0, Min and Max in mHz */
 	int frequencies[3];
 };
@@ -116,5 +113,6 @@ int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
 
 /* List of extended channel specification for all sensors */
 extern const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[];
+extern const struct attribute *cros_ec_sensor_fifo_attributes[];
 
 #endif  /* __CROS_EC_SENSORS_CORE_H */