iio: cros: unify hw fifo attributes without API changes

Commit 2e2366c2d141 ("iio: cros_ec: unify hw fifo attributes into the core file")
should be reverted as it set buffer extended attributes at
the wrong place. However, to revert it will requires to revert more
commits:
commit 165aea80e2e2 ("iio: cros_ec: use devm_iio_triggered_buffer_setup_ext()")
commit 21232b4456ba ("iio: buffer: remove iio_buffer_set_attrs() helper")).
and we would still have conflict with more recent development.
commit ee708e6baacd ("iio: buffer: introduce support for attaching more IIO buffers")

Instead, this commit reverts the first 2 commits without re-adding
iio_buffer_set_attrs() and set the buffer extended attributes at the
right place:

1. Instead of adding has_fw_fifo, deduct it from the configuration:
- EC must support FIFO (EC_FEATURE_MOTION_SENSE_FIFO) set.
- sensors send data a regular interval (accelerometer, gyro,
magnetomer, barometer, light sensor).
- "Legacy accelerometer" is only present on EC without FIFO, so we don't
need to set buffer attributes.

2. devm_iio_triggered_buffer_setup_ext() does not need to be called when
EC does not support FIFO, as there is no FIFO to manage.

3. Use devm_iio_triggered_buffer_setup_ext() when EC has a FIFO to
specify the buffer extended attributes.

Fixes: 2e2366c2d141 ("iio: cros_ec: unify hw fifo attributes into the core file")
Fixes: 165aea80e2e2 ("iio: cros_ec: use devm_iio_triggered_buffer_setup_ext()")
Signed-off-by: Gwendal Grignou <[e-mail]>
Reviewed-by: Alexandru Ardelean <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/accel/cros_ec_accel_legacy.c

···
 		return -ENOMEM;
 
 	ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
-					cros_ec_sensors_capture, NULL, false);
+					cros_ec_sensors_capture, NULL);
 	if (ret)
 		return ret;
 

drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c

···
 	if (!indio_dev)
 		return -ENOMEM;
 
-	ret = cros_ec_sensors_core_init(pdev, indio_dev, false, NULL,
-					NULL, false);
+	ret = cros_ec_sensors_core_init(pdev, indio_dev, false, NULL, NULL);
 	if (ret)
 		return ret;
 

drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c

···
 
 	ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
 					cros_ec_sensors_capture,
-					cros_ec_sensors_push_data,
-					true);
+					cros_ec_sensors_push_data);
 	if (ret)
 		return ret;
 

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c

···
 #include <linux/iio/iio.h>
 #include <linux/iio/kfifo_buf.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/kernel.h>
···
  *    for backward compatibility.
  * @push_data:          function to call when cros_ec_sensorhub receives
  *    a sample for that sensor.
- * @has_hw_fifo:	Set true if this device has/uses a HW FIFO
  *
  * Return: 0 on success, -errno on failure.
  */
···
 			      struct iio_dev *indio_dev,
 			      bool physical_device,
 			      cros_ec_sensors_capture_t trigger_capture,
-			      cros_ec_sensorhub_push_data_cb_t push_data,
-			      bool has_hw_fifo)
+			      cros_ec_sensorhub_push_data_cb_t push_data)
 {
 	struct device *dev = &pdev->dev;
 	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
···
 			 * We can not use trigger here, as events are generated
 			 * as soon as sample_frequency is set.
 			 */
-			ret = devm_iio_kfifo_buffer_setup(dev, indio_dev,
-							  INDIO_BUFFER_SOFTWARE,
-							  NULL);
+			ret = devm_iio_kfifo_buffer_setup_ext(dev, indio_dev,
+							      INDIO_BUFFER_SOFTWARE, NULL,
+							      cros_ec_sensor_fifo_attributes);
 			if (ret)
 				return ret;
 
···
 			ret = iio_device_set_clock(indio_dev, CLOCK_BOOTTIME);
 			if (ret)
 				return ret;
+
 		} else {
-			const struct attribute **fifo_attrs;
-
-			if (has_hw_fifo)
-				fifo_attrs = cros_ec_sensor_fifo_attributes;
-			else
-				fifo_attrs = NULL;
-
 			/*
 			 * The only way to get samples in buffer is to set a
 			 * software trigger (systrig, hrtimer).
 			 */
-			ret = devm_iio_triggered_buffer_setup_ext(
-					dev, indio_dev, NULL, trigger_capture,
-					NULL, fifo_attrs);
+			ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+					NULL, trigger_capture, NULL);
 			if (ret)
 				return ret;
 		}

drivers/iio/light/cros_ec_light_prox.c

···
 
 	ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
 					cros_ec_sensors_capture,
-					cros_ec_sensors_push_data,
-					true);
+					cros_ec_sensors_push_data);
 	if (ret)
 		return ret;
 

drivers/iio/pressure/cros_ec_baro.c

···
 
 	ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
 					cros_ec_sensors_capture,
-					cros_ec_sensors_push_data,
-					true);
+					cros_ec_sensors_push_data);
 	if (ret)
 		return ret;
 

include/linux/iio/common/cros_ec_sensors_core.h

···
 int cros_ec_sensors_core_init(struct platform_device *pdev,
 			      struct iio_dev *indio_dev, bool physical_device,
 			      cros_ec_sensors_capture_t trigger_capture,
-			      cros_ec_sensorhub_push_data_cb_t push_data,
-			      bool has_hw_fifo);
+			      cros_ec_sensorhub_push_data_cb_t push_data);
 
 irqreturn_t cros_ec_sensors_capture(int irq, void *p);
 int cros_ec_sensors_push_data(struct iio_dev *indio_dev,