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Message-ID: <f0584025-6dbb-44ab-bcaf-19827a45fa37@t-8ch.de>
Date: Fri, 20 Jun 2025 07:05:19 +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 v4 3/3] hwmon: (cros_ec) register fans into thermal
framework cooling devices
On 2025-06-19 15:42:56+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>
Also some tiny nitpicks below, with these fixed:
Acked-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
> Documentation/hwmon/cros_ec_hwmon.rst | 2 +
> drivers/hwmon/cros_ec_hwmon.c | 85 +++++++++++++++++++++++++++++++++++
> 2 files changed, 87 insertions(+)
>
> diff --git a/Documentation/hwmon/cros_ec_hwmon.rst b/Documentation/hwmon/cros_ec_hwmon.rst
> index 355557a08c9a54b4c177bafde3743e7dc02218be..6db812708325f7abb6d319af3312b4079e6923c6 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 to what they were before suspended when resumed.
> +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 c0c4ffa6f85419edf5dacd730192e7f1c28e2e5c..572b194e51fb1a05fa5151abb0826d1c8ba2948d 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>
> #include <linux/types.h>
> #include <linux/units.h>
>
> @@ -31,6 +32,11 @@ struct cros_ec_hwmon_priv {
> u8 manual_fan_pwm[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;
> @@ -306,6 +312,42 @@ 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;
> +
> + ret = cros_ec_hwmon_read_pwm_value(priv->hwmon_priv->cros_ec, priv->index, &read_val);
> + if (ret)
> + return ret;
> +
> + *val = read_val;
> + return ret;
return 0;
> +}
> +
> +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 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,
> +};
> +
> static const struct hwmon_ops cros_ec_hwmon_ops = {
> .read = cros_ec_hwmon_read,
> .read_string = cros_ec_hwmon_read_string,
> @@ -381,6 +423,48 @@ static bool cros_ec_hwmon_probe_fan_control_supported(struct cros_ec_device *cro
> is_cros_ec_cmd_available(cros_ec, EC_CMD_THERMAL_AUTO_FAN_CTRL, CROS_EC_HWMON_THERMAL_AUTO_FAN_CTRL_CMD_VERSION);
> }
>
> +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;
> + struct thermal_cooling_device *cdev;
> + char *type;
const char *type;
> + 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) {
> + dev_warn(dev, "no memory for registering fan %zu as a cooling device\n", i);
> + continue;
> + }
> +
> + type = devm_kasprintf(dev, GFP_KERNEL, "%s-fan%zu", dev_name(dev), i);
> + if (!type) {
> + dev_warn(dev, "no memory to compose cooling device type for fan %zu\n", i);
> + continue;
> + }
> +
> + cpriv->hwmon_priv = priv;
> + cpriv->index = i;
> + cdev = devm_thermal_of_cooling_device_register(dev, NULL, type, cpriv,
> + &cros_ec_thermal_cooling_ops);
> + if (IS_ERR(cdev)) {
> + dev_warn(dev, "failed to register fan %zu as a cooling device: %pe\n", i,
> + cdev);
> + continue;
> + }
> + }
> +}
> +
> static int cros_ec_hwmon_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -408,6 +492,7 @@ 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);
> + 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);
>
> --
> 2.50.0.rc2.701.gf1e915cc24-goog
>
>
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