[PATCH 2/5] hwmon: (cros_ec) Add support for fan target speed

[Thomas Weißschuh]

Use EC_CMD_PWM_GET_FAN_TARGET_RPM to retrieve the target fan speed.
The CrOS EC only supports this for the first fan.

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
 Documentation/hwmon/cros_ec_hwmon.rst |  6 +++++-
 drivers/hwmon/cros_ec_hwmon.c         | 26 +++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/Documentation/hwmon/cros_ec_hwmon.rst b/Documentation/hwmon/cros_ec_hwmon.rst
index 47ecae983bdb..4aede331baeb 100644
--- a/Documentation/hwmon/cros_ec_hwmon.rst
+++ b/Documentation/hwmon/cros_ec_hwmon.rst
@@ -23,4 +23,8 @@ ChromeOS embedded controller used in Chromebooks and other devices.
 
 The channel labels exposed via hwmon are retrieved from the EC itself.
 
-Fan and temperature readings are supported.
+Supported features:
+
+  - Current fan speed
+  - Target fan speed (for fan 1 only)
+  - Current temperature
diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index 5514cf780b8b..09b8057e1223 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -36,6 +36,20 @@ static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index
 	return 0;
 }
 
+static int cros_ec_hwmon_read_fan_target(struct cros_ec_device *cros_ec, u16 *speed)
+{
+	struct ec_response_pwm_get_fan_rpm resp;
+	int ret;
+
+	ret = cros_ec_cmd(cros_ec, 0, EC_CMD_PWM_GET_FAN_TARGET_RPM,
+			  NULL, 0, &resp, sizeof(resp));
+	if (ret < 0)
+		return ret;
+
+	*speed = resp.rpm;
+	return 0;
+}
+
 static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
 {
 	unsigned int offset;
@@ -91,6 +105,11 @@ static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 			ret = cros_ec_hwmon_read_fan_speed(priv->cros_ec, channel, &speed);
 			if (ret == 0)
 				*val = cros_ec_hwmon_is_error_fan(speed);
+
+		} else if (attr == hwmon_fan_target) {
+			ret = cros_ec_hwmon_read_fan_target(priv->cros_ec, &speed);
+			if (ret == 0)
+				*val = speed;
 		}
 	} else if (type == hwmon_temp) {
 		if (attr == hwmon_temp_input) {
@@ -128,8 +147,13 @@ static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_type
 					u32 attr, int channel)
 {
 	const struct cros_ec_hwmon_priv *priv = data;
+	u16 speed;
 
 	if (type == hwmon_fan) {
+		if (attr == hwmon_fan_target &&
+		    cros_ec_hwmon_read_fan_target(priv->cros_ec, &speed) == -EOPNOTSUPP)
+			return 0;
+
 		if (priv->usable_fans & BIT(channel))
 			return 0444;
 	} else if (type == hwmon_temp) {
@@ -142,7 +166,7 @@ static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_type
 
 static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
 	HWMON_CHANNEL_INFO(fan,
-			   HWMON_F_INPUT | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_FAULT | HWMON_F_TARGET,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT),

-- 
2.45.2