From: Sung-Chi Li <lschyi@chromium.org>

Newer EC firmware supports controlling fans through host commands, so
adding corresponding implementations for controlling these fans in the
driver for other kernel services and userspace to control them.

The driver will first probe the supported host command versions (get and
set of fan PWM values, get and set of fan control mode) to see if the
connected EC fulfills the requirements of controlling the fan, then
exposes corresponding sysfs nodes for userspace to control the fan with
corresponding read and write implementations.
As EC will automatically change the fan mode to auto when the device is
suspended, the power management hooks are added as well to keep the fan
control mode and fan PWM value consistent during suspend and resume. As
we need to access the hwmon device in the power management hook, update
the driver by storing the hwmon device in the driver data as well.

Signed-off-by: Sung-Chi Li <lschyi@chromium.org>
---
 Documentation/hwmon/cros_ec_hwmon.rst |   5 +-
 drivers/hwmon/cros_ec_hwmon.c         | 228 ++++++++++++++++++++++++++++++++++
 2 files changed, 232 insertions(+), 1 deletion(-)

diff --git a/Documentation/hwmon/cros_ec_hwmon.rst b/Documentation/hwmon/cros_ec_hwmon.rst
index 47ecae983bdbef4bfcafc5dd2fff3de039f77f8e..355557a08c9a54b4c177bafde3743e7dc02218be 100644
--- a/Documentation/hwmon/cros_ec_hwmon.rst
+++ b/Documentation/hwmon/cros_ec_hwmon.rst
@@ -23,4 +23,7 @@ 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.
+Fan and temperature readings are supported. PWM fan control is also supported if
+the EC also supports setting fan PWM values and fan mode. Note that EC will
+switch fan control mode back to auto when suspended. This driver will restore
+the fan state to what they were before suspended when resumed.
diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index 9991c3fa020ac859cbbff29dfb669e53248df885..884be1d34000c1a7485a381373c78329108dd427 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -7,6 +7,7 @@
 
 #include <linux/device.h>
 #include <linux/hwmon.h>
+#include <linux/math.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -17,10 +18,17 @@
 
 #define DRV_NAME	"cros-ec-hwmon"
 
+#define CROS_EC_HWMON_PWM_GET_FAN_DUTY_CMD_VERSION	0
+#define CROS_EC_HWMON_PWM_SET_FAN_DUTY_CMD_VERSION	1
+#define CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION	2
+
 struct cros_ec_hwmon_priv {
 	struct cros_ec_device *cros_ec;
 	const char *temp_sensor_names[EC_TEMP_SENSOR_ENTRIES + EC_TEMP_SENSOR_B_ENTRIES];
 	u8 usable_fans;
+	bool fan_control_supported;
+	u8 manual_fans; /* bits to indicate whether the fan is set to manual */
+	u8 manual_fan_pwm_values[EC_FAN_SPEED_ENTRIES];
 };
 
 static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index, u16 *speed)
@@ -36,6 +44,42 @@ static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index
 	return 0;
 }
 
+static int cros_ec_hwmon_read_pwm_value(struct cros_ec_device *cros_ec, u8 index, u8 *pwm_value)
+{
+	struct ec_params_pwm_get_fan_duty req = {
+		.fan_idx = index,
+	};
+	struct ec_response_pwm_get_fan_duty resp;
+	int ret;
+
+	ret = cros_ec_cmd(cros_ec, CROS_EC_HWMON_PWM_GET_FAN_DUTY_CMD_VERSION,
+			  EC_CMD_PWM_GET_FAN_DUTY, &req, sizeof(req), &resp, sizeof(resp));
+	if (ret < 0)
+		return ret;
+
+	*pwm_value = (u8)DIV_ROUND_CLOSEST(le32_to_cpu(resp.percent) * 255, 100);
+	return 0;
+}
+
+static int cros_ec_hwmon_read_pwm_enable(struct cros_ec_device *cros_ec, u8 index,
+					 u8 *control_method)
+{
+	struct ec_params_auto_fan_ctrl_v2 req = {
+		.cmd = EC_AUTO_FAN_CONTROL_CMD_GET,
+		.fan_idx = index,
+	};
+	struct ec_response_auto_fan_control resp;
+	int ret;
+
+	ret = cros_ec_cmd(cros_ec, CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION,
+			  EC_CMD_THERMAL_AUTO_FAN_CTRL, &req, sizeof(req), &resp, sizeof(resp));
+	if (ret < 0)
+		return ret;
+
+	*control_method = resp.is_auto ? 2 : 1;
+	return 0;
+}
+
 static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
 {
 	unsigned int offset;
@@ -73,7 +117,9 @@ static long cros_ec_hwmon_temp_to_millicelsius(u8 temp)
 static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 			      u32 attr, int channel, long *val)
 {
+	u8 control_method;
 	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
+	u8 pwm_value;
 	int ret = -EOPNOTSUPP;
 	u16 speed;
 	u8 temp;
@@ -92,6 +138,16 @@ static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 			if (ret == 0)
 				*val = cros_ec_hwmon_is_error_fan(speed);
 		}
+	} else if (type == hwmon_pwm) {
+		if (attr == hwmon_pwm_enable) {
+			ret = cros_ec_hwmon_read_pwm_enable(priv->cros_ec, channel, &control_method);
+			if (ret == 0)
+				*val = control_method;
+		} else if (attr == hwmon_pwm_input) {
+			ret = cros_ec_hwmon_read_pwm_value(priv->cros_ec, channel, &pwm_value);
+			if (ret == 0)
+				*val = pwm_value;
+		}
 	} else if (type == hwmon_temp) {
 		if (attr == hwmon_temp_input) {
 			ret = cros_ec_hwmon_read_temp(priv->cros_ec, channel, &temp);
@@ -124,6 +180,74 @@ static int cros_ec_hwmon_read_string(struct device *dev, enum hwmon_sensor_types
 	return -EOPNOTSUPP;
 }
 
+static int cros_ec_hwmon_set_fan_pwm_val(struct cros_ec_device *cros_ec, u8 index, u8 val)
+{
+	struct ec_params_pwm_set_fan_duty_v1 req = {
+		.fan_idx = index,
+		.percent = DIV_ROUND_CLOSEST((uint32_t)val * 100, 255),
+	};
+	int ret;
+
+	ret = cros_ec_cmd(cros_ec, CROS_EC_HWMON_PWM_SET_FAN_DUTY_CMD_VERSION,
+			  EC_CMD_PWM_SET_FAN_DUTY, &req, sizeof(req), NULL, 0);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int cros_ec_hwmon_write_pwm_input(struct cros_ec_device *cros_ec, u8 index, u8 val)
+{
+	u8 control_method;
+	int ret;
+
+	ret = cros_ec_hwmon_read_pwm_enable(cros_ec, index, &control_method);
+	if (ret)
+		return ret;
+	if (control_method != 1)
+		return -EOPNOTSUPP;
+
+	return cros_ec_hwmon_set_fan_pwm_val(cros_ec, index, val);
+}
+
+static int cros_ec_hwmon_write_pwm_enable(struct cros_ec_device *cros_ec, u8 index, u8 val)
+{
+	struct ec_params_auto_fan_ctrl_v2 req = {
+		.fan_idx = index,
+		.cmd = EC_AUTO_FAN_CONTROL_CMD_SET,
+	};
+	int ret;
+
+	/* No CROS EC supports no fan speed control */
+	if (val == 0)
+		return -EOPNOTSUPP;
+
+	req.set_auto = (val != 1) ? true : false;
+	ret = cros_ec_cmd(cros_ec, CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION,
+			  EC_CMD_THERMAL_AUTO_FAN_CTRL, &req, sizeof(req), NULL, 0);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int cros_ec_hwmon_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+			       int channel, long val)
+{
+	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
+
+	if (type == hwmon_pwm) {
+		switch (attr) {
+		case hwmon_pwm_input:
+			return cros_ec_hwmon_write_pwm_input(priv->cros_ec, channel, val);
+		case hwmon_pwm_enable:
+			return cros_ec_hwmon_write_pwm_enable(priv->cros_ec, channel, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	}
+
+	return -EOPNOTSUPP;
+}
+
 static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
 					u32 attr, int channel)
 {
@@ -132,6 +256,9 @@ static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_type
 	if (type == hwmon_fan) {
 		if (priv->usable_fans & BIT(channel))
 			return 0444;
+	} else if (type == hwmon_pwm) {
+		if (priv->fan_control_supported && priv->usable_fans & BIT(channel))
+			return 0644;
 	} else if (type == hwmon_temp) {
 		if (priv->temp_sensor_names[channel])
 			return 0444;
@@ -147,6 +274,11 @@ static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
 	HWMON_CHANNEL_INFO(temp,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_LABEL,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_LABEL,
@@ -178,6 +310,7 @@ static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
 static const struct hwmon_ops cros_ec_hwmon_ops = {
 	.read = cros_ec_hwmon_read,
 	.read_string = cros_ec_hwmon_read_string,
+	.write = cros_ec_hwmon_write,
 	.is_visible = cros_ec_hwmon_is_visible,
 };
 
@@ -233,6 +366,25 @@ static void cros_ec_hwmon_probe_fans(struct cros_ec_hwmon_priv *priv)
 	}
 }
 
+static inline bool is_cros_ec_cmd_fulfilled(struct cros_ec_device *cros_ec,
+					    u16 cmd, u8 version)
+{
+	int ret;
+
+	ret = cros_ec_get_cmd_versions(cros_ec, cmd);
+	return ret >= 0 && (ret & EC_VER_MASK(version));
+}
+
+static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cros_ec)
+{
+	if (!IS_ENABLED(CONFIG_PM))
+		return false;
+
+	return is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_PWM_GET_FAN_DUTY, CROS_EC_HWMON_PWM_GET_FAN_DUTY_CMD_VERSION) &&
+	       is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_PWM_SET_FAN_DUTY, CROS_EC_HWMON_PWM_SET_FAN_DUTY_CMD_VERSION) &&
+	       is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_THERMAL_AUTO_FAN_CTRL, CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION);
+}
+
 static int cros_ec_hwmon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -259,13 +411,87 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
 
 	cros_ec_hwmon_probe_temp_sensors(dev, priv, thermal_version);
 	cros_ec_hwmon_probe_fans(priv);
+	priv->fan_control_supported = cros_ec_hwmon_probe_fan_control_supported(priv->cros_ec);
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
 							 &cros_ec_hwmon_chip_info, NULL);
+	platform_set_drvdata(pdev, priv);
 
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }
 
+static int cros_ec_hwmon_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	u8 control_method;
+	size_t i;
+	struct cros_ec_hwmon_priv *priv = platform_get_drvdata(pdev);
+	int ret;
+
+	if (!priv->fan_control_supported)
+		return 0;
+
+	/* EC sets fan control to auto after suspended, store settings before suspending. */
+	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
+		if (!(priv->usable_fans & BIT(i)))
+			continue;
+
+		ret = cros_ec_hwmon_read_pwm_enable(priv->cros_ec, i, &control_method);
+		if (ret) {
+			dev_warn(&pdev->dev, "failed to get mode setting for fan %zu: %d", i, ret);
+			continue;
+		}
+
+		if (control_method != 1) {
+			priv->manual_fans &= ~BIT(i);
+			continue;
+		} else {
+			priv->manual_fans |= BIT(i);
+		}
+
+		ret = cros_ec_hwmon_read_pwm_value(
+			priv->cros_ec, i, &priv->manual_fan_pwm_values[i]);
+		/*
+		 * If failed for storing the value, invalidate the stored mode value by setting it
+		 * to auto control. EC will automatically switch to auto mode for that fan after
+		 * suspended.
+		 */
+		if (ret) {
+			priv->manual_fans &= ~BIT(i);
+			dev_warn(&pdev->dev, "failed to get PWM setting for fan %zu: %d", i, ret);
+			continue;
+		}
+	}
+
+	return 0;
+}
+
+static int cros_ec_hwmon_resume(struct platform_device *pdev)
+{
+	size_t i;
+	const struct cros_ec_hwmon_priv *priv = platform_get_drvdata(pdev);
+	int ret;
+
+	if (!priv->fan_control_supported)
+		return 0;
+
+	/* EC sets fan control to auto after suspended, restore to settings before suspended. */
+	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
+		if (!(priv->manual_fans & BIT(i)))
+			continue;
+
+		/*
+		 * Setting fan PWM value to EC will change the mode to manual for that fan in EC as
+		 * well, so we do not need to issue a separate fan mode to manual call.
+		 */
+		ret = cros_ec_hwmon_set_fan_pwm_val(
+			priv->cros_ec, i, priv->manual_fan_pwm_values[i]);
+		if (ret)
+			dev_warn(&pdev->dev, "failed to restore settings for fan %zu: %d", i, ret);
+	}
+
+	return 0;
+}
+
 static const struct platform_device_id cros_ec_hwmon_id[] = {
 	{ DRV_NAME, 0 },
 	{}
@@ -274,6 +500,8 @@ static const struct platform_device_id cros_ec_hwmon_id[] = {
 static struct platform_driver cros_ec_hwmon_driver = {
 	.driver.name	= DRV_NAME,
 	.probe		= cros_ec_hwmon_probe,
+	.suspend	= pm_ptr(cros_ec_hwmon_suspend),
+	.resume		= pm_ptr(cros_ec_hwmon_resume),
 	.id_table	= cros_ec_hwmon_id,
 };
 module_platform_driver(cros_ec_hwmon_driver);

-- 
2.49.0.1015.ga840276032-goog

On 2025-05-12 15:11:56+0800, Sung-Chi Li via B4 Relay wrote:
> From: Sung-Chi Li <lschyi@chromium.org>
> 
> Newer EC firmware supports controlling fans through host commands, so
> adding corresponding implementations for controlling these fans in the
> driver for other kernel services and userspace to control them.
> 
> The driver will first probe the supported host command versions (get and
> set of fan PWM values, get and set of fan control mode) to see if the
> connected EC fulfills the requirements of controlling the fan, then
> exposes corresponding sysfs nodes for userspace to control the fan with
> corresponding read and write implementations.
> As EC will automatically change the fan mode to auto when the device is
> suspended, the power management hooks are added as well to keep the fan
> control mode and fan PWM value consistent during suspend and resume. As
> we need to access the hwmon device in the power management hook, update
> the driver by storing the hwmon device in the driver data as well.
> 
> Signed-off-by: Sung-Chi Li <lschyi@chromium.org>
> ---
>  Documentation/hwmon/cros_ec_hwmon.rst |   5 +-
>  drivers/hwmon/cros_ec_hwmon.c         | 228 ++++++++++++++++++++++++++++++++++
>  2 files changed, 232 insertions(+), 1 deletion(-)

<snip>

>  static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
>  {
>  	unsigned int offset;
> @@ -73,7 +117,9 @@ static long cros_ec_hwmon_temp_to_millicelsius(u8 temp)
>  static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>  			      u32 attr, int channel, long *val)
>  {
> +	u8 control_method;
>  	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> +	u8 pwm_value;
>  	int ret = -EOPNOTSUPP;
>  	u16 speed;
>  	u8 temp;

Ordering again.

This should be:

struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
int ret = -EOPNOTSUPP;
u8 control_method;
u8 pwm_value;
u16 speed;
u8 temp;

or:

struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
u8 control_method, pwm_value, temp;
int ret = -EOPNOTSUPP;
u16 speed;

<snip>

> +static inline bool is_cros_ec_cmd_fulfilled(struct cros_ec_device *cros_ec,
> +					    u16 cmd, u8 version)

"fulfilled" -> "available" or "present"

> +{
> +	int ret;
> +
> +	ret = cros_ec_get_cmd_versions(cros_ec, cmd);
> +	return ret >= 0 && (ret & EC_VER_MASK(version));
> +}
> +
> +static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cros_ec)
> +{
> +	if (!IS_ENABLED(CONFIG_PM))
> +		return false;

Why? This should generally work fine without CONFIG_PM.
Only the suspend/resume callbacks are unnecessary in that case.

> +
> +	return is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_PWM_GET_FAN_DUTY, CROS_EC_HWMON_PWM_GET_FAN_DUTY_CMD_VERSION) &&
> +	       is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_PWM_SET_FAN_DUTY, CROS_EC_HWMON_PWM_SET_FAN_DUTY_CMD_VERSION) &&
> +	       is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_THERMAL_AUTO_FAN_CTRL, CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION);
> +}

<snip>

> +static int cros_ec_hwmon_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	u8 control_method;
> +	size_t i;
> +	struct cros_ec_hwmon_priv *priv = platform_get_drvdata(pdev);
> +	int ret;

Ordering.

> +
> +	if (!priv->fan_control_supported)
> +		return 0;
> +
> +	/* EC sets fan control to auto after suspended, store settings before suspending. */
> +	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
> +		if (!(priv->usable_fans & BIT(i)))
> +			continue;
> +
> +		ret = cros_ec_hwmon_read_pwm_enable(priv->cros_ec, i, &control_method);
> +		if (ret) {
> +			dev_warn(&pdev->dev, "failed to get mode setting for fan %zu: %d", i, ret);
> +			continue;
> +		}
> +
> +		if (control_method != 1) {
> +			priv->manual_fans &= ~BIT(i);
> +			continue;
> +		} else {
> +			priv->manual_fans |= BIT(i);
> +		}
> +
> +		ret = cros_ec_hwmon_read_pwm_value(
> +			priv->cros_ec, i, &priv->manual_fan_pwm_values[i]);
> +		/*
> +		 * If failed for storing the value, invalidate the stored mode value by setting it

"If storing the value failed"

> +		 * to auto control. EC will automatically switch to auto mode for that fan after
> +		 * suspended.
> +		 */
> +		if (ret) {
> +			priv->manual_fans &= ~BIT(i);
> +			dev_warn(&pdev->dev, "failed to get PWM setting for fan %zu: %d", i, ret);

Print the warning first, so it's easier to follow the logic.

> +			continue;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int cros_ec_hwmon_resume(struct platform_device *pdev)
> +{
> +	size_t i;
> +	const struct cros_ec_hwmon_priv *priv = platform_get_drvdata(pdev);
> +	int ret;

Ordering.

> +
> +	if (!priv->fan_control_supported)
> +		return 0;
> +
> +	/* EC sets fan control to auto after suspended, restore to settings before suspended. */

"after suspend"

> +	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
> +		if (!(priv->manual_fans & BIT(i)))
> +			continue;
> +
> +		/*
> +		 * Setting fan PWM value to EC will change the mode to manual for that fan in EC as
> +		 * well, so we do not need to issue a separate fan mode to manual call.
> +		 */
> +		ret = cros_ec_hwmon_set_fan_pwm_val(
> +			priv->cros_ec, i, priv->manual_fan_pwm_values[i]);

You could rename "manual_fan_pwm_values" to "manual_fan_pwm" to save
some linebreaks here and in _suspend().

> +		if (ret)
> +			dev_warn(&pdev->dev, "failed to restore settings for fan %zu: %d", i, ret);

You can use %pe to print errors instead of %d:

"%zu: %pe\n", i, ERR_PTR(ret);

Also missing newline at the end of the message.

> +	}
> +
> +	return 0;
> +}

<snip>

On Mon, May 12, 2025 at 09:30:39AM +0200, Thomas Weißschuh wrote:

Sorry for the late reply, I missed mails for this series.

> On 2025-05-12 15:11:56+0800, Sung-Chi Li via B4 Relay wrote:
> > From: Sung-Chi Li <lschyi@chromium.org>
> >  static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
> >  {
> >  	unsigned int offset;
> > @@ -73,7 +117,9 @@ static long cros_ec_hwmon_temp_to_millicelsius(u8 temp)
> >  static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> >  			      u32 attr, int channel, long *val)
> >  {
> > +	u8 control_method;
> >  	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> > +	u8 pwm_value;
> >  	int ret = -EOPNOTSUPP;
> >  	u16 speed;
> >  	u8 temp;
> 
> Ordering again.
> 
> This should be:
> 
> struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> int ret = -EOPNOTSUPP;
> u8 control_method;
> u8 pwm_value;
> u16 speed;
> u8 temp;
> 
> or:
> 
> struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> u8 control_method, pwm_value, temp;
> int ret = -EOPNOTSUPP;
> u16 speed;
> 
> <snip>
> 

Would you mind to share the sorting logic, so I do not bother you with checking
these styling issue? Initially, I thought the sorting is based on the variable
name, but after seeing your example (which I am appreciated), I am not sure how
the sorting works. Is it sorted along with the variable types (
"u8 control_method", "u16 speed", etc)? If that is the case, why "u16 speed" is
in the middle of the u8 group variables?

> > +static inline bool is_cros_ec_cmd_fulfilled(struct cros_ec_device *cros_ec,
> > +					    u16 cmd, u8 version)
> 
> "fulfilled" -> "available" or "present"
> 
> > +{
> > +	int ret;
> > +
> > +	ret = cros_ec_get_cmd_versions(cros_ec, cmd);
> > +	return ret >= 0 && (ret & EC_VER_MASK(version));
> > +}
> > +
> > +static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cros_ec)
> > +{
> > +	if (!IS_ENABLED(CONFIG_PM))
> > +		return false;
> 
> Why? This should generally work fine without CONFIG_PM.
> Only the suspend/resume callbacks are unnecessary in that case.
> 

I treat fan control should include restoring the fan setting after resume, so
I think if no CONFIG_PM, the fan control is not complete. I am good with
removing this check, and if you have any thoughts after this explanation, please
share with me, otherwise I will remove it in the next series.

On 6/18/25 00:26, Sung-Chi Li wrote:
> On Mon, May 12, 2025 at 09:30:39AM +0200, Thomas Weißschuh wrote:
> 
> Sorry for the late reply, I missed mails for this series.
> 
>> On 2025-05-12 15:11:56+0800, Sung-Chi Li via B4 Relay wrote:
>>> From: Sung-Chi Li <lschyi@chromium.org>
>>>   static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
>>>   {
>>>   	unsigned int offset;
>>> @@ -73,7 +117,9 @@ static long cros_ec_hwmon_temp_to_millicelsius(u8 temp)
>>>   static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>>>   			      u32 attr, int channel, long *val)
>>>   {
>>> +	u8 control_method;
>>>   	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
>>> +	u8 pwm_value;
>>>   	int ret = -EOPNOTSUPP;
>>>   	u16 speed;
>>>   	u8 temp;
>>
>> Ordering again.
>>
>> This should be:
>>
>> struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
>> int ret = -EOPNOTSUPP;
>> u8 control_method;
>> u8 pwm_value;
>> u16 speed;
>> u8 temp;
>>
>> or:
>>
>> struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
>> u8 control_method, pwm_value, temp;
>> int ret = -EOPNOTSUPP;
>> u16 speed;
>>
>> <snip>
>>
> 
> Would you mind to share the sorting logic, so I do not bother you with checking
> these styling issue? Initially, I thought the sorting is based on the variable
> name, but after seeing your example (which I am appreciated), I am not sure how
> the sorting works. Is it sorted along with the variable types (
> "u8 control_method", "u16 speed", etc)? If that is the case, why "u16 speed" is
> in the middle of the u8 group variables?
> 


It is called "reverse christmas tree". Longer lines first.

Guenter

On 2025-06-18 15:26:38+0800, Sung-Chi Li wrote:
> On Mon, May 12, 2025 at 09:30:39AM +0200, Thomas Weißschuh wrote:
> 
> Sorry for the late reply, I missed mails for this series.
> 
> > On 2025-05-12 15:11:56+0800, Sung-Chi Li via B4 Relay wrote:
> > > From: Sung-Chi Li <lschyi@chromium.org>
> > >  static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
> > >  {
> > >  	unsigned int offset;
> > > @@ -73,7 +117,9 @@ static long cros_ec_hwmon_temp_to_millicelsius(u8 temp)
> > >  static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> > >  			      u32 attr, int channel, long *val)
> > >  {
> > > +	u8 control_method;
> > >  	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> > > +	u8 pwm_value;
> > >  	int ret = -EOPNOTSUPP;
> > >  	u16 speed;
> > >  	u8 temp;
> > 
> > Ordering again.
> > 
> > This should be:
> > 
> > struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> > int ret = -EOPNOTSUPP;
> > u8 control_method;
> > u8 pwm_value;
> > u16 speed;
> > u8 temp;
> > 
> > or:
> > 
> > struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
> > u8 control_method, pwm_value, temp;
> > int ret = -EOPNOTSUPP;
> > u16 speed;
> > 
> > <snip>
> > 
> 
> Would you mind to share the sorting logic, so I do not bother you with checking
> these styling issue? Initially, I thought the sorting is based on the variable
> name, but after seeing your example (which I am appreciated), I am not sure how
> the sorting works. Is it sorted along with the variable types (
> "u8 control_method", "u16 speed", etc)? If that is the case, why "u16 speed" is
> in the middle of the u8 group variables?

Welp, I really should have explained this, instead of assuming it to be
obvious, sorry. The sorting is based on the length of the line, AKA
the "reverse christmas tree".

While this is not a strict rule, the driver is already using it, so I'd
like to stick to it. "Bonus points" for preserving preserving
semantically useful ordering within the line-length based one.

> > > +static inline bool is_cros_ec_cmd_fulfilled(struct cros_ec_device *cros_ec,
> > > +					    u16 cmd, u8 version)
> > 
> > "fulfilled" -> "available" or "present"
> > 
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = cros_ec_get_cmd_versions(cros_ec, cmd);
> > > +	return ret >= 0 && (ret & EC_VER_MASK(version));
> > > +}
> > > +
> > > +static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cros_ec)
> > > +{
> > > +	if (!IS_ENABLED(CONFIG_PM))
> > > +		return false;
> > 
> > Why? This should generally work fine without CONFIG_PM.
> > Only the suspend/resume callbacks are unnecessary in that case.
> > 
> 
> I treat fan control should include restoring the fan setting after resume, so
> I think if no CONFIG_PM, the fan control is not complete. I am good with
> removing this check, and if you have any thoughts after this explanation, please
> share with me, otherwise I will remove it in the next series.

As far as I understand, with CONFIG_PM=n the kernel won't be able to do
any suspend/resume. So cros_ec_hwmon won't need to handle the
suspend/resume case. However even then the regular UAPI for fan duty
management is useful for users.


Thomas