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Message-ID: <b2432c5c-2589-4cfe-821f-47e5128af2d0@t-8ch.de>
Date: Sat, 3 May 2025 09:27:18 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: lschyi@...omium.org
Cc: Benson Leung <bleung@...omium.org>, 
	Guenter Roeck <groeck@...omium.org>, Jean Delvare <jdelvare@...e.com>, 
	Guenter Roeck <linux@...ck-us.net>, Jonathan Corbet <corbet@....net>, 
	chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org, 
	linux-doc@...r.kernel.org, Sung-Chi Li <lschyi@...gle.com>
Subject: Re: [PATCH v2 3/3] hwmon: (cros_ec) register fans into thermal
 framework cooling devices

On 2025-05-02 13:34:47+0800, Sung-Chi Li via B4 Relay wrote:
> From: Sung-Chi Li <lschyi@...omium.org>
> 
> Register fans connected under EC as thermal cooling devices as well, so
> these fans can then work with the thermal framework.
> 
> During the driver probing phase, we will also try to register each fan
> as a thermal cooling device based on previous probe result (whether the
> there are fans connected on that channel, and whether EC supports fan
> control). The basic get max state, get current state, and set current
> state methods are then implemented as well.
> 
> Signed-off-by: Sung-Chi Li <lschyi@...omium.org>
> ---
>  Documentation/hwmon/cros_ec_hwmon.rst |  2 ++
>  drivers/hwmon/cros_ec_hwmon.c         | 66 +++++++++++++++++++++++++++++++++++
>  2 files changed, 68 insertions(+)
> 
> diff --git a/Documentation/hwmon/cros_ec_hwmon.rst b/Documentation/hwmon/cros_ec_hwmon.rst
> index 5b802be120438732529c3d25b1afa8b4ee353305..82c75bdaf912a116eaafa3149dc1252b3f7007d2 100644
> --- a/Documentation/hwmon/cros_ec_hwmon.rst
> +++ b/Documentation/hwmon/cros_ec_hwmon.rst
> @@ -27,3 +27,5 @@ 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 before suspended.
> +If a fan is controllable, this driver will register that fan as a cooling device
> +in the thermal framework as well.
> diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
> index c5e42e2a03a0c8c68d3f8afbb2bb45b93a58b955..abfcf44fb7505189124e78c651b0eb1e0533b4e8 100644
> --- a/drivers/hwmon/cros_ec_hwmon.c
> +++ b/drivers/hwmon/cros_ec_hwmon.c
> @@ -13,6 +13,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/platform_data/cros_ec_commands.h>
>  #include <linux/platform_data/cros_ec_proto.h>
> +#include <linux/thermal.h>

Needs a dependency on CONFIG_THERMAL.

>  #include <linux/types.h>
>  #include <linux/units.h>
>  
> @@ -27,6 +28,11 @@ struct cros_ec_hwmon_priv {
>  	u8 manual_fan_pwm_values[EC_FAN_SPEED_ENTRIES];
>  };
>  
> +struct cros_ec_hwmon_cooling_priv {
> +	struct cros_ec_hwmon_priv *hwmon_priv;
> +	u8 index;
> +};
> +
>  static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index, u16 *speed)
>  {
>  	int ret;
> @@ -300,6 +306,34 @@ static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
>  	NULL
>  };
>  
> +static int
> +cros_ec_hwmon_cooling_get_max_state(struct thermal_cooling_device *cdev,
> +				    unsigned long *val)
> +{
> +	*val = 255;
> +	return 0;
> +}
> +
> +static int cros_ec_hwmon_cooling_get_cur_state(struct thermal_cooling_device *cdev,
> +					       unsigned long *val)
> +{
> +	const struct cros_ec_hwmon_cooling_priv *priv = cdev->devdata;
> +	u8 read_val;
> +	int ret = cros_ec_hwmon_read_pwm_value(priv->hwmon_priv->cros_ec, priv->index, &read_val);

Split declaration and assignment.

> +
> +	if (ret == 0)
> +		*val = read_val;
> +	return ret;
> +}
> +
> +static int cros_ec_hwmon_cooling_set_cur_state(struct thermal_cooling_device *cdev,
> +					       unsigned long val)
> +{
> +	const struct cros_ec_hwmon_cooling_priv *priv = cdev->devdata;
> +
> +	return cros_ec_hwmon_write_pwm_input(priv->hwmon_priv->cros_ec, priv->index, val);
> +}
> +
>  static const struct hwmon_ops cros_ec_hwmon_ops = {
>  	.read = cros_ec_hwmon_read,
>  	.read_string = cros_ec_hwmon_read_string,
> @@ -307,6 +341,12 @@ static const struct hwmon_ops cros_ec_hwmon_ops = {
>  	.is_visible = cros_ec_hwmon_is_visible,
>  };
>  
> +static const struct thermal_cooling_device_ops cros_ec_thermal_cooling_ops = {
> +	.get_max_state = cros_ec_hwmon_cooling_get_max_state,
> +	.get_cur_state = cros_ec_hwmon_cooling_get_cur_state,
> +	.set_cur_state = cros_ec_hwmon_cooling_set_cur_state,
> +};

Move this directly after the definition of the functions.

> +
>  static const struct hwmon_chip_info cros_ec_hwmon_chip_info = {
>  	.ops = &cros_ec_hwmon_ops,
>  	.info = cros_ec_hwmon_info,
> @@ -374,6 +414,31 @@ static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cro
>  	       is_cros_ec_cmd_fulfilled(cros_ec, EC_CMD_THERMAL_AUTO_FAN_CTRL, 2);
>  }
>  
> +static void cros_ec_hwmon_register_fan_cooling_devices(struct device *dev,
> +						       struct cros_ec_hwmon_priv *priv)
> +{
> +	struct cros_ec_hwmon_cooling_priv *cpriv;
> +	size_t i;

if (!IS_ENABLED(CONFIG_THERMAL))
	return;

> +
> +	if (!priv->fan_control_supported)
> +		return;
> +
> +	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
> +		if (!(priv->usable_fans & BIT(i)))
> +			continue;
> +
> +		cpriv = devm_kzalloc(dev, sizeof(*cpriv), GFP_KERNEL);
> +		if (!cpriv)
> +			return;
> +
> +		cpriv->hwmon_priv = priv;
> +		cpriv->index = i;
> +		devm_thermal_of_cooling_device_register(
> +			dev, NULL, devm_kasprintf(dev, GFP_KERNEL, "cros-ec-fan%zu", i), cpriv,

What happens for multiple/chained ECs? If both provide sensors the
thermal device names will collide.

Error handling for devm_kasprintf() is missing.

> +			&cros_ec_thermal_cooling_ops);

Error handling for devm_thermal_of_cooling_device_register() is missing.

> +	}
> +}
> +
>  static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -402,6 +467,7 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  	cros_ec_hwmon_probe_fans(priv);
>  	priv->fan_control_supported =
>  		cros_ec_hwmon_probe_fan_control_supported(priv->cros_ec);
> +	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
>  
>  	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
>  							 &cros_ec_hwmon_chip_info, NULL);
> 
> -- 
> 2.49.0.906.g1f30a19c02-goog
> 
> 

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