iio: common: cros_ec_sensors: Expose cros_ec_sensors frequency range via iio sysfs

Embedded controller return minimum and maximum frequencies, unfortunately
we have no way to know the step for all available frequencies.
Even if not complete, we can return a list of known values using the
standard read_avail callback (IIO_CHAN_INFO_SAMP_FREQ) to provide them to
userland.

Now cros_ec_* sensors provides frequencies values in sysfs like this:
"0 min max". 0 is always true to disable the sensor.

Default frequencies are provided for earlier protocol.
Signed-off-by: Nick Vaccaro <nvaccaro@chromium.org>
Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
[rebased on top of iio/testing and solved conflicts]
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c

@@ -215,6 +215,7 @@ static int cros_ec_sensors_write(struct iio_dev *indio_dev,
 static const struct iio_info ec_sensors_info = {
 	.read_raw = &cros_ec_sensors_read,
 	.write_raw = &cros_ec_sensors_write,
+	.read_avail = &cros_ec_sensors_core_read_avail,
 };
 
 static int cros_ec_sensors_probe(struct platform_device *pdev)
@@ -252,6 +253,8 @@ static int cros_ec_sensors_probe(struct platform_device *pdev)
 			BIT(IIO_CHAN_INFO_SCALE) |
 			BIT(IIO_CHAN_INFO_FREQUENCY) |
 			BIT(IIO_CHAN_INFO_SAMP_FREQ);
+		channel->info_mask_shared_by_all_available =
+			BIT(IIO_CHAN_INFO_SAMP_FREQ);
 		channel->scan_type.realbits = CROS_EC_SENSOR_BITS;
 		channel->scan_type.storagebits = CROS_EC_SENSOR_BITS;
 		channel->scan_index = i;

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c

@@ -50,6 +50,37 @@ static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
 	return ret;
 }
 
+static void get_default_min_max_freq(enum motionsensor_type type,
+				     u32 *min_freq,
+				     u32 *max_freq)
+{
+	switch (type) {
+	case MOTIONSENSE_TYPE_ACCEL:
+	case MOTIONSENSE_TYPE_GYRO:
+		*min_freq = 12500;
+		*max_freq = 100000;
+		break;
+	case MOTIONSENSE_TYPE_MAG:
+		*min_freq = 5000;
+		*max_freq = 25000;
+		break;
+	case MOTIONSENSE_TYPE_PROX:
+	case MOTIONSENSE_TYPE_LIGHT:
+		*min_freq = 100;
+		*max_freq = 50000;
+		break;
+	case MOTIONSENSE_TYPE_BARO:
+		*min_freq = 250;
+		*max_freq = 20000;
+		break;
+	case MOTIONSENSE_TYPE_ACTIVITY:
+	default:
+		*min_freq = 0;
+		*max_freq = 0;
+		break;
+	}
+}
+
 int cros_ec_sensors_core_init(struct platform_device *pdev,
 			      struct iio_dev *indio_dev,
 			      bool physical_device)
@@ -104,6 +135,19 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
 
 		/* Set sign vector, only used for backward compatibility. */
 		memset(state->sign, 1, CROS_EC_SENSOR_MAX_AXIS);
+
+		/* 0 is a correct value used to stop the device */
+		state->frequencies[0] = 0;
+		if (state->msg->version < 3) {
+			get_default_min_max_freq(state->resp->info.type,
+						 &state->frequencies[1],
+						 &state->frequencies[2]);
+		} else {
+			state->frequencies[1] =
+			    state->resp->info_3.min_frequency;
+			state->frequencies[2] =
+			    state->resp->info_3.max_frequency;
+		}
 	}
 
 	return 0;
@@ -471,6 +515,27 @@ int cros_ec_sensors_core_read(struct cros_ec_sensors_core_state *st,
 }
 EXPORT_SYMBOL_GPL(cros_ec_sensors_core_read);
 
+int cros_ec_sensors_core_read_avail(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan,
+				    const int **vals,
+				    int *type,
+				    int *length,
+				    long mask)
+{
+	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*length = ARRAY_SIZE(state->frequencies);
+		*vals = (const int *)&state->frequencies;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(cros_ec_sensors_core_read_avail);
+
 int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
 			       struct iio_chan_spec const *chan,
 			       int val, int val2, long mask)

drivers/iio/light/cros_ec_light_prox.c

@@ -162,6 +162,7 @@ static int cros_ec_light_prox_write(struct iio_dev *indio_dev,
 static const struct iio_info cros_ec_light_prox_info = {
 	.read_raw = &cros_ec_light_prox_read,
 	.write_raw = &cros_ec_light_prox_write,
+	.read_avail = &cros_ec_sensors_core_read_avail,
 };
 
 static int cros_ec_light_prox_probe(struct platform_device *pdev)
@@ -196,6 +197,8 @@ static int cros_ec_light_prox_probe(struct platform_device *pdev)
 	channel->info_mask_shared_by_all =
 		BIT(IIO_CHAN_INFO_SAMP_FREQ) |
 		BIT(IIO_CHAN_INFO_FREQUENCY);
+	channel->info_mask_shared_by_all_available =
+		BIT(IIO_CHAN_INFO_SAMP_FREQ);
 	channel->scan_type.realbits = CROS_EC_SENSOR_BITS;
 	channel->scan_type.storagebits = CROS_EC_SENSOR_BITS;
 	channel->scan_type.shift = 0;

include/linux/iio/common/cros_ec_sensors_core.h

@@ -73,6 +73,9 @@ struct cros_ec_sensors_core_state {
 				    unsigned long scan_mask, s16 *data);
 
 	int curr_sampl_freq;
+
+	/* Table of known available frequencies : 0, Min and Max in mHz */
+	int frequencies[3];
 };
 
 /**
@@ -153,6 +156,24 @@ int cros_ec_sensors_core_read(struct cros_ec_sensors_core_state *st,
 			      struct iio_chan_spec const *chan,
 			      int *val, int *val2, long mask);
 
+/**
+ * cros_ec_sensors_core_read_avail() - get available values
+ * @indio_dev:		pointer to state information for device
+ * @chan:	channel specification structure table
+ * @vals:	list of available values
+ * @type:	type of data returned
+ * @length:	number of data returned in the array
+ * @mask:	specifies which values to be requested
+ *
+ * Return:	an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST
+ */
+int cros_ec_sensors_core_read_avail(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan,
+				    const int **vals,
+				    int *type,
+				    int *length,
+				    long mask);
+
 /**
  * cros_ec_sensors_core_write() - function to write a value to the sensor
  * @st:		pointer to state information for device