platform/x86: alienware-wmi-wmax: Add support for manual fan control

All models with the "AWCC" WMAX device support a way of manually
controlling fans.

The PWM duty cycle of a fan can't be controlled directly. Instead the
AWCC interface let's us tune a fan `boost` value, which has the
following empirically discovered, approximate behavior over the PWM
value:

	pwm = pwm_base + (fan_boost / 255) * (pwm_max - pwm_base)

Where the pwm_base is the locked PWM value controlled by the FW and
fan_boost is a value between 0 and 255.

Expose this fan_boost knob as a custom HWMON attribute.

Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: linux-hwmon@vger.kernel.org
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Link: https://lore.kernel.org/r/20250329-hwm-v7-8-a14ea39d8a94@gmail.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/dell/alienware-wmi-wmax.c

@@ -14,8 +14,12 @@
 #include <linux/bits.h>
 #include <linux/dmi.h>
 #include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/kstrtox.h>
+#include <linux/minmax.h>
 #include <linux/moduleparam.h>
 #include <linux/platform_profile.h>
+#include <linux/pm.h>
 #include <linux/units.h>
 #include <linux/wmi.h>
 #include "alienware-wmi.h"
@@ -183,10 +187,12 @@ enum AWCC_THERMAL_INFORMATION_OPERATIONS {
 	AWCC_OP_GET_FAN_MIN_RPM			= 0x08,
 	AWCC_OP_GET_FAN_MAX_RPM			= 0x09,
 	AWCC_OP_GET_CURRENT_PROFILE		= 0x0B,
+	AWCC_OP_GET_FAN_BOOST			= 0x0C,
 };
 
 enum AWCC_THERMAL_CONTROL_OPERATIONS {
 	AWCC_OP_ACTIVATE_PROFILE		= 0x01,
+	AWCC_OP_SET_FAN_BOOST			= 0x02,
 };
 
 enum AWCC_GAME_SHIFT_STATUS_OPERATIONS {
@@ -250,6 +256,7 @@ struct awcc_fan_data {
 	const char *label;
 	u32 min_rpm;
 	u32 max_rpm;
+	u8 suspend_cache;
 	u8 id;
 };
 
@@ -638,6 +645,18 @@ static int awcc_op_get_temperature(struct wmi_device *wdev, u8 temp_id, u32 *out
 	return awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_INFORMATION, &args, out);
 }
 
+static int awcc_op_get_fan_boost(struct wmi_device *wdev, u8 fan_id, u32 *out)
+{
+	struct wmax_u32_args args = {
+		.operation = AWCC_OP_GET_FAN_BOOST,
+		.arg1 = fan_id,
+		.arg2 = 0,
+		.arg3 = 0,
+	};
+
+	return awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_INFORMATION, &args, out);
+}
+
 static int awcc_op_get_current_profile(struct wmi_device *wdev, u32 *out)
 {
 	struct wmax_u32_args args = {
@@ -663,6 +682,19 @@ static int awcc_op_activate_profile(struct wmi_device *wdev, u8 profile)
 	return awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_CONTROL, &args, &out);
 }
 
+static int awcc_op_set_fan_boost(struct wmi_device *wdev, u8 fan_id, u8 boost)
+{
+	struct wmax_u32_args args = {
+		.operation = AWCC_OP_SET_FAN_BOOST,
+		.arg1 = fan_id,
+		.arg2 = boost,
+		.arg3 = 0,
+	};
+	u32 out;
+
+	return awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_CONTROL, &args, &out);
+}
+
 /*
  * HWMON
  *  - Provides temperature and fan speed monitoring as well as manual fan
@@ -827,6 +859,81 @@ static const struct hwmon_chip_info awcc_hwmon_chip_info = {
 	.info = awcc_hwmon_info,
 };
 
+static ssize_t fan_boost_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct awcc_priv *priv = dev_get_drvdata(dev);
+	int index = to_sensor_dev_attr(attr)->index;
+	struct awcc_fan_data *fan = priv->fan_data[index];
+	u32 boost;
+	int ret;
+
+	ret = awcc_op_get_fan_boost(priv->wdev, fan->id, &boost);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%u\n", boost);
+}
+
+static ssize_t fan_boost_store(struct device *dev, struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct awcc_priv *priv = dev_get_drvdata(dev);
+	int index = to_sensor_dev_attr(attr)->index;
+	struct awcc_fan_data *fan = priv->fan_data[index];
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	ret = awcc_op_set_fan_boost(priv->wdev, fan->id, clamp_val(val, 0, 255));
+
+	return ret ? ret : count;
+}
+
+static SENSOR_DEVICE_ATTR_RW(fan1_boost, fan_boost, 0);
+static SENSOR_DEVICE_ATTR_RW(fan2_boost, fan_boost, 1);
+static SENSOR_DEVICE_ATTR_RW(fan3_boost, fan_boost, 2);
+static SENSOR_DEVICE_ATTR_RW(fan4_boost, fan_boost, 3);
+static SENSOR_DEVICE_ATTR_RW(fan5_boost, fan_boost, 4);
+static SENSOR_DEVICE_ATTR_RW(fan6_boost, fan_boost, 5);
+
+static umode_t fan_boost_attr_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+	struct awcc_priv *priv = dev_get_drvdata(kobj_to_dev(kobj));
+
+	return n < priv->fan_count ? attr->mode : 0;
+}
+
+static bool fan_boost_group_visible(struct kobject *kobj)
+{
+	return true;
+}
+
+DEFINE_SYSFS_GROUP_VISIBLE(fan_boost);
+
+static struct attribute *fan_boost_attrs[] = {
+	&sensor_dev_attr_fan1_boost.dev_attr.attr,
+	&sensor_dev_attr_fan2_boost.dev_attr.attr,
+	&sensor_dev_attr_fan3_boost.dev_attr.attr,
+	&sensor_dev_attr_fan4_boost.dev_attr.attr,
+	&sensor_dev_attr_fan5_boost.dev_attr.attr,
+	&sensor_dev_attr_fan6_boost.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group fan_boost_group = {
+	.attrs = fan_boost_attrs,
+	.is_visible = SYSFS_GROUP_VISIBLE(fan_boost),
+};
+
+static const struct attribute_group *awcc_hwmon_groups[] = {
+	&fan_boost_group,
+	NULL
+};
+
 static int awcc_hwmon_temps_init(struct wmi_device *wdev)
 {
 	struct awcc_priv *priv = dev_get_drvdata(&wdev->dev);
@@ -964,12 +1071,56 @@ static int awcc_hwmon_init(struct wmi_device *wdev)
 	if (ret)
 		return ret;
 
-	priv->hwdev = devm_hwmon_device_register_with_info(&wdev->dev, "alienware_wmi", priv,
+	priv->hwdev = devm_hwmon_device_register_with_info(&wdev->dev, "alienware_wmi",
-							   &awcc_hwmon_chip_info, NULL);
+							   priv, &awcc_hwmon_chip_info,
+							   awcc_hwmon_groups);
 
 	return PTR_ERR_OR_ZERO(priv->hwdev);
 }
 
+static void awcc_hwmon_suspend(struct device *dev)
+{
+	struct awcc_priv *priv = dev_get_drvdata(dev);
+	struct awcc_fan_data *fan;
+	unsigned int i;
+	u32 boost;
+	int ret;
+
+	for (i = 0; i < priv->fan_count; i++) {
+		fan = priv->fan_data[i];
+
+		ret = awcc_thermal_information(priv->wdev, AWCC_OP_GET_FAN_BOOST,
+					       fan->id, &boost);
+		if (ret)
+			dev_err(dev, "Failed to store Fan %u boost while suspending\n", i);
+
+		fan->suspend_cache = ret ? 0 : clamp_val(boost, 0, 255);
+
+		awcc_op_set_fan_boost(priv->wdev, fan->id, 0);
+		if (ret)
+			dev_err(dev, "Failed to set Fan %u boost to 0 while suspending\n", i);
+	}
+}
+
+static void awcc_hwmon_resume(struct device *dev)
+{
+	struct awcc_priv *priv = dev_get_drvdata(dev);
+	struct awcc_fan_data *fan;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < priv->fan_count; i++) {
+		fan = priv->fan_data[i];
+
+		if (!fan->suspend_cache)
+			continue;
+
+		ret = awcc_op_set_fan_boost(priv->wdev, fan->id, fan->suspend_cache);
+		if (ret)
+			dev_err(dev, "Failed to restore Fan %u boost while resuming\n", i);
+	}
+}
+
 /*
  * Thermal Profile control
  *  - Provides thermal profile control through the Platform Profile API
@@ -1196,6 +1347,24 @@ static int wmax_wmi_probe(struct wmi_device *wdev, const void *context)
 	return ret;
 }
 
+static int wmax_wmi_suspend(struct device *dev)
+{
+	if (awcc->hwmon)
+		awcc_hwmon_suspend(dev);
+
+	return 0;
+}
+
+static int wmax_wmi_resume(struct device *dev)
+{
+	if (awcc->hwmon)
+		awcc_hwmon_resume(dev);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(wmax_wmi_pm_ops, wmax_wmi_suspend, wmax_wmi_resume);
+
 static const struct wmi_device_id alienware_wmax_device_id_table[] = {
 	{ WMAX_CONTROL_GUID, NULL },
 	{ },
@@ -1206,6 +1375,7 @@ static struct wmi_driver alienware_wmax_wmi_driver = {
 	.driver = {
 		.name = "alienware-wmi-wmax",
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.pm = pm_sleep_ptr(&wmax_wmi_pm_ops),
 	},
 	.id_table = alienware_wmax_device_id_table,
 	.probe = wmax_wmi_probe,