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Message-ID: <57e155e6-6ccc-f5b0-3f8e-efcd8ba18bb0@roeck-us.net>
Date: Sun, 10 Apr 2022 06:43:22 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Pali Rohár <pali@...nel.org>,
Armin Wolf <W_Armin@....de>
Cc: jdelvare@...e.com, linux-hwmon@...r.kernel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (dell-smm) Add cooling device support
On 4/10/22 03:08, Pali Rohár wrote:
> On Saturday 09 April 2022 17:33:48 Armin Wolf wrote:
>> Am 30.03.22 um 18:33 schrieb Armin Wolf:
>>
>>> Until now, only the temperature sensors where exported thru
>>> the thermal subsystem. Export the fans as "dell-smm-fan[1-3]" too
>>> to make them available as cooling devices.
>>> Also update Documentation.
>>>
>>> Signed-off-by: Armin Wolf <W_Armin@....de>
>>> ---
>>> Documentation/hwmon/dell-smm-hwmon.rst | 7 ++
>>> drivers/hwmon/Kconfig | 1 +
>>> drivers/hwmon/dell-smm-hwmon.c | 94 +++++++++++++++++++++++++-
>>> 3 files changed, 99 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/Documentation/hwmon/dell-smm-hwmon.rst b/Documentation/hwmon/dell-smm-hwmon.rst
>>> index d3323a96665d..41839b7de2c1 100644
>>> --- a/Documentation/hwmon/dell-smm-hwmon.rst
>>> +++ b/Documentation/hwmon/dell-smm-hwmon.rst
>>> @@ -86,6 +86,13 @@ probe the BIOS on your machine and discover the appropriate codes.
>>>
>>> Again, when you find new codes, we'd be happy to have your patches!
>>>
>>> +``thermal`` interface
>>> +---------------------------
>>> +
>>> +The driver also exports the fans as thermal cooling devices with
>>> +``type`` set to ``dell-smm-fan[1-3]``. This allows for easy fan control
>>> +using one of the thermal governors.
>>> +
>>> Module parameters
>>> -----------------
>>>
>>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>>> index 9ab4e9b3d27b..1175b8e38c45 100644
>>> --- a/drivers/hwmon/Kconfig
>>> +++ b/drivers/hwmon/Kconfig
>>> @@ -498,6 +498,7 @@ config SENSORS_DS1621
>>> config SENSORS_DELL_SMM
>>> tristate "Dell laptop SMM BIOS hwmon driver"
>>> depends on X86
>>> + imply THERMAL
>>> help
>>> This hwmon driver adds support for reporting temperature of different
>>> sensors and controls the fans on Dell laptops via System Management
>>> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
>>> index 84cb1ede7bc0..0c29386f4bd3 100644
>>> --- a/drivers/hwmon/dell-smm-hwmon.c
>>> +++ b/drivers/hwmon/dell-smm-hwmon.c
>>> @@ -21,6 +21,7 @@
>>> #include <linux/errno.h>
>>> #include <linux/hwmon.h>
>>> #include <linux/init.h>
>>> +#include <linux/kconfig.h>
>>> #include <linux/kernel.h>
>>> #include <linux/module.h>
>>> #include <linux/mutex.h>
>>> @@ -29,6 +30,7 @@
>>> #include <linux/seq_file.h>
>>> #include <linux/string.h>
>>> #include <linux/smp.h>
>>> +#include <linux/thermal.h>
>>> #include <linux/types.h>
>>> #include <linux/uaccess.h>
>>>
>>> @@ -80,6 +82,11 @@ struct dell_smm_data {
>>> int *fan_nominal_speed[DELL_SMM_NO_FANS];
>>> };
>>>
>>> +struct dell_smm_cooling_data {
>>> + u8 fan_num;
>>> + struct dell_smm_data *data;
>>> +};
>>> +
>>> MODULE_AUTHOR("Massimo Dal Zotto (dz@...ian.org)");
>>> MODULE_AUTHOR("Pali Rohár <pali@...nel.org>");
>>> MODULE_DESCRIPTION("Dell laptop SMM BIOS hwmon driver");
>>> @@ -638,9 +645,50 @@ static void __init i8k_init_procfs(struct device *dev)
>>>
>>> #endif
>>>
>>> -/*
>>> - * Hwmon interface
>>> - */
>>> +static int dell_smm_get_max_state(struct thermal_cooling_device *dev, unsigned long *state)
>>> +{
>>> + struct dell_smm_cooling_data *cdata = dev->devdata;
>>> +
>>> + *state = cdata->data->i8k_fan_max;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int dell_smm_get_cur_state(struct thermal_cooling_device *dev, unsigned long *state)
>>> +{
>>> + struct dell_smm_cooling_data *cdata = dev->devdata;
>>> + int ret;
>>> +
>>> + ret = i8k_get_fan_status(cdata->data, cdata->fan_num);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + *state = ret;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int dell_smm_set_cur_state(struct thermal_cooling_device *dev, unsigned long state)
>>> +{
>>> + struct dell_smm_cooling_data *cdata = dev->devdata;
>>> + struct dell_smm_data *data = cdata->data;
>>> + int ret;
>>> +
>>> + if (state > data->i8k_fan_max)
>>> + return -EINVAL;
>>> +
>>> + mutex_lock(&data->i8k_mutex);
>>> + ret = i8k_set_fan(data, cdata->fan_num, (int)state);
>>> + mutex_unlock(&data->i8k_mutex);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static const struct thermal_cooling_device_ops dell_smm_cooling_ops = {
>>> + .get_max_state = dell_smm_get_max_state,
>>> + .get_cur_state = dell_smm_get_cur_state,
>>> + .set_cur_state = dell_smm_set_cur_state,
>>> +};
>>>
>>> static umode_t dell_smm_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
>>> int channel)
>>> @@ -941,6 +989,37 @@ static const struct hwmon_chip_info dell_smm_chip_info = {
>>> .info = dell_smm_info,
>>> };
>>>
>>> +static int __init dell_smm_init_cdev(struct device *dev, u8 fan_num)
>>> +{
>>> + struct dell_smm_data *data = dev_get_drvdata(dev);
>>> + struct thermal_cooling_device *cdev;
>>> + struct dell_smm_cooling_data *cdata;
>>> + int ret = 0;
>>> + char *name;
>>> +
>>> + name = kasprintf(GFP_KERNEL, "dell-smm-fan%u", fan_num + 1);
>>> + if (!name)
>>> + return -ENOMEM;
>>> +
>>> + cdata = devm_kmalloc(dev, sizeof(*cdata), GFP_KERNEL);
>>> + if (cdata) {
>>> + cdata->fan_num = fan_num;
>>> + cdata->data = data;
>>> + cdev = devm_thermal_of_cooling_device_register(dev, NULL, name, cdata,
>>> + &dell_smm_cooling_ops);
>>> + if (IS_ERR(cdev)) {
>>> + devm_kfree(dev, cdata);
>>> + ret = PTR_ERR(cdev);
>>> + }
>>> + } else {
>>> + ret = -ENOMEM;
>>> + }
>>> +
>>> + kfree(name);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> static int __init dell_smm_init_hwmon(struct device *dev)
>>> {
>>> struct dell_smm_data *data = dev_get_drvdata(dev);
>>> @@ -967,6 +1046,15 @@ static int __init dell_smm_init_hwmon(struct device *dev)
>>> continue;
>>>
>>> data->fan[i] = true;
>>> +
>>> + /* the cooling device it not critical, ignore failures */
>>> + if (IS_REACHABLE(CONFIG_THERMAL)) {
>>> + err = dell_smm_init_cdev(dev, i);
>>> + if (err < 0)
>>> + dev_err(dev, "Failed to register cooling device for fan %u\n",
>>> + i + 1);
>>> + }
>>> +
>>> data->fan_nominal_speed[i] = devm_kmalloc_array(dev, data->i8k_fan_max + 1,
>>> sizeof(*data->fan_nominal_speed[i]),
>>> GFP_KERNEL);
>>> --
>>> 2.30.2
>>>
>> Any thoughts on this? I tested it on a Dell Inspiron 3505, so i can prove it works.
>
> Hello! If hwmon maintainers are happy with this approach and this new
> API then I'm fine with it. Maybe one thing to discuss, should not be
> dell_smm_init_cdev() fatal on error?
"the cooling device it not critical, ignore failures"
Besides the misspelling - if it is not fatal, the code should not use
dev_err() but dev_warning(). Other than that I am ok as well.
Guenter
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