platform/x86: asus-wmi: Expand support of GPU fan to read RPM and label

The previously added patch to add support for pwm change for TUF laptops
also is usuable for more than TUF. The same method `0x00110014` is
used to read the fan RPM.

Add two extra attributes for reading fan2 plus fan2 label.
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20220916004623.10992-1-luke@ljones.devReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/asus-wmi.c

@@ -72,6 +72,7 @@ module_param(fnlock_default, bool, 0444);
 
 #define ASUS_WMI_FNLOCK_BIOS_DISABLED	BIT(0)
 
+#define ASUS_GPU_FAN_DESC		"gpu_fan"
 #define ASUS_FAN_DESC			"cpu_fan"
 #define ASUS_FAN_MFUN			0x13
 #define ASUS_FAN_SFUN_READ		0x06
@@ -2078,6 +2079,30 @@ static ssize_t asus_hwmon_temp1(struct device *dev,
 }
 
 /* GPU fan on modern ROG laptops */
+static ssize_t fan2_input_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+	int value;
+	int ret;
+
+	ret = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_GPU_FAN_CTRL, &value);
+	if (ret < 0)
+		return ret;
+
+	value &= 0xffff;
+
+	return sysfs_emit(buf, "%d\n", value * 100);
+}
+
+static ssize_t fan2_label_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	return sysfs_emit(buf, "%s\n", ASUS_GPU_FAN_DESC);
+}
+
 static ssize_t pwm2_enable_show(struct device *dev,
 				struct device_attribute *attr,
 				char *buf)
@@ -2127,9 +2152,12 @@ static ssize_t pwm2_enable_store(struct device *dev,
 /* Fan1 */
 static DEVICE_ATTR_RW(pwm1);
 static DEVICE_ATTR_RW(pwm1_enable);
-static DEVICE_ATTR_RW(pwm2_enable);
 static DEVICE_ATTR_RO(fan1_input);
 static DEVICE_ATTR_RO(fan1_label);
+/* Fan2 - GPU fan */
+static DEVICE_ATTR_RW(pwm2_enable);
+static DEVICE_ATTR_RO(fan2_input);
+static DEVICE_ATTR_RO(fan2_label);
 
 /* Temperature */
 static DEVICE_ATTR(temp1_input, S_IRUGO, asus_hwmon_temp1, NULL);
@@ -2140,6 +2168,8 @@ static struct attribute *hwmon_attributes[] = {
 	&dev_attr_pwm2_enable.attr,
 	&dev_attr_fan1_input.attr,
 	&dev_attr_fan1_label.attr,
+	&dev_attr_fan2_input.attr,
+	&dev_attr_fan2_label.attr,
 
 	&dev_attr_temp1_input.attr,
 	NULL
@@ -2160,7 +2190,9 @@ static umode_t asus_hwmon_sysfs_is_visible(struct kobject *kobj,
 	    || attr == &dev_attr_pwm1_enable.attr) {
 		if (asus->fan_type == FAN_TYPE_NONE)
 			return 0;
-	} else if (attr == &dev_attr_pwm2_enable.attr) {
+	} else if (attr == &dev_attr_fan2_input.attr
+	    || attr == &dev_attr_fan2_label.attr
+	    || attr == &dev_attr_pwm2_enable.attr) {
 		if (asus->gpu_fan_type == FAN_TYPE_NONE)
 			return 0;
 	} else if (attr == &dev_attr_temp1_input.attr) {