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Message-ID: <f857fcdb-0da1-4bc7-9e7a-541317d8b424@roeck-us.net>
Date: Sat, 3 May 2025 06:00:20 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Thomas Weißschuh <linux@...ssschuh.net>,
lschyi@...omium.org
Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>,
Jean Delvare <jdelvare@...e.com>, 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 5/3/25 00:27, Thomas Weißschuh wrote:
> 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;
Also, error handling always comes first.
if (ret)
return ret;
*val = read_val;
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 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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