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 <nvacc...@chromium.org>
Signed-off-by: Fabien Lahoudere <fabien.lahoud...@collabora.com>
---
 .../common/cros_ec_sensors/cros_ec_sensors.c  |  3 +
 .../cros_ec_sensors/cros_ec_sensors_core.c    | 65 +++++++++++++++++++
 drivers/iio/light/cros_ec_light_prox.c        |  3 +
 .../linux/iio/common/cros_ec_sensors_core.h   | 21 ++++++
 4 files changed, 92 insertions(+)

diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c 
b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
index 17af4e0fd5f8..2f1b6d8d617b 100644
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
+++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
@@ -175,6 +175,7 @@ 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)
@@ -211,6 +212,8 @@ 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;
diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c 
b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
index 81111af8a167..805652250960 100644
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
+++ b/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)
@@ -100,6 +131,19 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
                }
                state->type = state->resp->info.type;
                state->loc = state->resp->info.location;
+
+               /* 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;
@@ -461,6 +505,27 @@ 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)
diff --git a/drivers/iio/light/cros_ec_light_prox.c 
b/drivers/iio/light/cros_ec_light_prox.c
index 308ee6ff2e22..c62cb022b6bc 100644
--- a/drivers/iio/light/cros_ec_light_prox.c
+++ b/drivers/iio/light/cros_ec_light_prox.c
@@ -164,6 +164,7 @@ 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)
@@ -198,6 +199,8 @@ 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;
diff --git a/include/linux/iio/common/cros_ec_sensors_core.h 
b/include/linux/iio/common/cros_ec_sensors_core.h
index 0c636b9fe8d7..a9623111f7c9 100644
--- a/include/linux/iio/common/cros_ec_sensors_core.h
+++ b/include/linux/iio/common/cros_ec_sensors_core.h
@@ -70,6 +70,9 @@ 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];
 };
 
 /**
@@ -150,6 +153,24 @@ 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
-- 
2.19.2

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