Re: [PATCH] hwmon: (dell-smm) Add cooling device support

From: Armin Wolf
Date: Sat Apr 09 2022 - 11:36:19 EST

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@xxxxxx>
---
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@xxxxxxxxxx)");
MODULE_AUTHOR("Pali Rohár <pali@xxxxxxxxxx>");
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.