[PATCH 2/3] iio: common: cros_ec_sensors: add sysfs attribute for frequencies

[Fabien Lahoudere <fabien.lahoudere@collabora.com>]

In order to provide minimum and maximum frequencies for each sensors,
we use a standard API (sampling_frequency_available) to provide them
to userland.
As cros_ec_sensors_core_init do not manage default attrs, we change
the signature to let all kind of sensors to provide "struct iio_info"
with their callback. This change impact drivers using that function.

Then cros_ec_* sensors provides frequencies range in sysfs like this:
[min step max]

Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
---
 .../common/cros_ec_sensors/cros_ec_sensors.c  |  6 +--
 .../cros_ec_sensors/cros_ec_sensors_core.c    | 38 +++++++++++++++++++
 drivers/iio/light/cros_ec_light_prox.c        |  6 +--
 drivers/iio/pressure/cros_ec_baro.c           |  6 +--
 .../linux/iio/common/cros_ec_sensors_core.h   |  4 +-
 5 files changed, 50 insertions(+), 10 deletions(-)

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..a0ecee15a6c8 100644
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
+++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
@@ -172,7 +172,7 @@ static int cros_ec_sensors_write(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static const struct iio_info ec_sensors_info = {
+static struct iio_info ec_sensors_info = {
 	.read_raw = &cros_ec_sensors_read,
 	.write_raw = &cros_ec_sensors_write,
 };
@@ -195,11 +195,11 @@ static int cros_ec_sensors_probe(struct platform_device *pdev)
 	if (!indio_dev)
 		return -ENOMEM;
 
-	ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
+	ret = cros_ec_sensors_core_init(pdev, indio_dev, &ec_sensors_info,
+					true);
 	if (ret)
 		return ret;
 
-	indio_dev->info = &ec_sensors_info;
 	state = iio_priv(indio_dev);
 	for (channel = state->channels, i = CROS_EC_SENSOR_X;
 	     i < CROS_EC_SENSOR_MAX_AXIS; i++, channel++) {
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 d5c8b4714ad6..2c2a608a10ec 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
@@ -10,6 +10,7 @@
 #include <linux/iio/buffer.h>
 #include <linux/iio/common/cros_ec_sensors_core.h>
 #include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
 #include <linux/iio/kfifo_buf.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/kernel.h>
@@ -97,8 +98,42 @@ static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
 	return ret;
 }
 
+/**
+ * cros_ec_sensors_read_freq() - sysfs function to get available frequencies
+ * @dev: Device structure for this device.
+ * @attr: Description of the attribute.
+ * @buf: Incoming string
+ *
+ * The later modes are only relevant to the ring buffer - and depend on current
+ * mode. Note that data sheet gives rather wide tolerances for these so integer
+ * division will give good enough answer and not all chips have them specified
+ * at all.
+ **/
+static ssize_t cros_ec_sensors_read_freq(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
+
+	return snprintf(buf, PAGE_SIZE, "[ %d 1 %d ]\n", state->min_freq,
+			state->max_freq);
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(cros_ec_sensors_read_freq);
+
+static struct attribute *cros_ec_sensors_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group cros_ec_sensors_attribute_group = {
+	.attrs = cros_ec_sensors_attributes,
+};
+
 int cros_ec_sensors_core_init(struct platform_device *pdev,
 			      struct iio_dev *indio_dev,
+			      struct iio_info *info,
 			      bool physical_device)
 {
 	struct device *dev = &pdev->dev;
@@ -164,6 +199,9 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
 		}
 	}
 
+	info->attrs = &cros_ec_sensors_attribute_group;
+	indio_dev->info = info;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cros_ec_sensors_core_init);
diff --git a/drivers/iio/light/cros_ec_light_prox.c b/drivers/iio/light/cros_ec_light_prox.c
index 308ee6ff2e22..1772e339cf14 100644
--- a/drivers/iio/light/cros_ec_light_prox.c
+++ b/drivers/iio/light/cros_ec_light_prox.c
@@ -161,7 +161,7 @@ static int cros_ec_light_prox_write(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static const struct iio_info cros_ec_light_prox_info = {
+static struct iio_info cros_ec_light_prox_info = {
 	.read_raw = &cros_ec_light_prox_read,
 	.write_raw = &cros_ec_light_prox_write,
 };
@@ -184,11 +184,11 @@ static int cros_ec_light_prox_probe(struct platform_device *pdev)
 	if (!indio_dev)
 		return -ENOMEM;
 
-	ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
+	ret = cros_ec_sensors_core_init(pdev, indio_dev,
+					&cros_ec_light_prox_info, true);
 	if (ret)
 		return ret;
 
-	indio_dev->info = &cros_ec_light_prox_info;
 	state = iio_priv(indio_dev);
 	state->core.type = state->core.resp->info.type;
 	state->core.loc = state->core.resp->info.location;
diff --git a/drivers/iio/pressure/cros_ec_baro.c b/drivers/iio/pressure/cros_ec_baro.c
index 034ce98d6e97..cd3be0f16226 100644
--- a/drivers/iio/pressure/cros_ec_baro.c
+++ b/drivers/iio/pressure/cros_ec_baro.c
@@ -107,7 +107,7 @@ static int cros_ec_baro_write(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static const struct iio_info cros_ec_baro_info = {
+static struct iio_info cros_ec_baro_info = {
 	.read_raw = &cros_ec_baro_read,
 	.write_raw = &cros_ec_baro_write,
 };
@@ -130,11 +130,11 @@ static int cros_ec_baro_probe(struct platform_device *pdev)
 	if (!indio_dev)
 		return -ENOMEM;
 
-	ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
+	ret = cros_ec_sensors_core_init(pdev, indio_dev, &cros_ec_baro_info,
+					true);
 	if (ret)
 		return ret;
 
-	indio_dev->info = &cros_ec_baro_info;
 	state = iio_priv(indio_dev);
 	state->core.type = state->core.resp->info.type;
 	state->core.loc = state->core.resp->info.location;
diff --git a/include/linux/iio/common/cros_ec_sensors_core.h b/include/linux/iio/common/cros_ec_sensors_core.h
index 4742a9637a85..7052cfb5884a 100644
--- a/include/linux/iio/common/cros_ec_sensors_core.h
+++ b/include/linux/iio/common/cros_ec_sensors_core.h
@@ -117,12 +117,14 @@ struct platform_device;
  * cros_ec_sensors_core_init() - basic initialization of the core structure
  * @pdev:		platform device created for the sensors
  * @indio_dev:		iio device structure of the device
+ * @info:		iio info structure with read and write callback
  * @physical_device:	true if the device refers to a physical device
  *
  * Return: 0 on success, -errno on failure.
  */
 int cros_ec_sensors_core_init(struct platform_device *pdev,
-			      struct iio_dev *indio_dev, bool physical_device);
+			      struct iio_dev *indio_dev, struct iio_info *info,
+			      bool physical_device);
 
 /**
  * cros_ec_sensors_capture() - the trigger handler function
-- 
2.20.1