platform/x86: asus-wmi: add support for showing charger mode

Expose a WMI method in sysfs platform for showing which connected
charger the laptop is currently using.
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230630053552.976579-2-luke@ljones.devSigned-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/ABI/testing/sysfs-platform-asus-wmi

@@ -98,3 +98,13 @@ Description:
 		Enable an LCD response-time boost to reduce or remove ghosting:
 			* 0 - Disable,
 			* 1 - Enable
+
+What:		/sys/devices/platform/<platform>/charge_mode
+Date:		Jun 2023
+KernelVersion:	6.5
+Contact:	"Luke Jones" <luke@ljones.dev>
+Description:
+		Get the current charging mode being used:
+			* 1 - Barrel connected charger,
+			* 2 - USB-C charging
+			* 3 - Both connected, barrel used for charging
\ No newline at end of file

drivers/platform/x86/asus-wmi.c

@@ -237,6 +237,7 @@ struct asus_wmi {
 	u8 fan_boost_mode_mask;
 	u8 fan_boost_mode;
 
+	bool charge_mode_available;
 	bool egpu_enable_available;
 	bool dgpu_disable_available;
 	bool gpu_mux_mode_available;
@@ -586,6 +587,22 @@ static void asus_wmi_tablet_mode_get_state(struct asus_wmi *asus)
 		asus_wmi_tablet_sw_report(asus, result);
 }
 
+/* Charging mode, 1=Barrel, 2=USB ******************************************/
+static ssize_t charge_mode_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+	int result, value;
+
+	result = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_CHARGE_MODE, &value);
+	if (result < 0)
+		return result;
+
+	return sysfs_emit(buf, "%d\n", value & 0xff);
+}
+
+static DEVICE_ATTR_RO(charge_mode);
+
 /* dGPU ********************************************************************/
 static ssize_t dgpu_disable_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
@@ -3462,6 +3479,7 @@ static struct attribute *platform_attributes[] = {
 	&dev_attr_camera.attr,
 	&dev_attr_cardr.attr,
 	&dev_attr_touchpad.attr,
+	&dev_attr_charge_mode.attr,
 	&dev_attr_egpu_enable.attr,
 	&dev_attr_dgpu_disable.attr,
 	&dev_attr_gpu_mux_mode.attr,
@@ -3491,6 +3509,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
 		devid = ASUS_WMI_DEVID_LID_RESUME;
 	else if (attr == &dev_attr_als_enable.attr)
 		devid = ASUS_WMI_DEVID_ALS_ENABLE;
+	else if (attr == &dev_attr_charge_mode.attr)
+		ok = asus->charge_mode_available;
 	else if (attr == &dev_attr_egpu_enable.attr)
 		ok = asus->egpu_enable_available;
 	else if (attr == &dev_attr_dgpu_disable.attr)
@@ -3757,6 +3777,7 @@ static int asus_wmi_add(struct platform_device *pdev)
 	if (err)
 		goto fail_platform;
 
+	asus->charge_mode_available = asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_CHARGE_MODE);
 	asus->egpu_enable_available = asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_EGPU);
 	asus->dgpu_disable_available = asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_DGPU);
 	asus->gpu_mux_mode_available = asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_GPU_MUX);

include/linux/platform_data/x86/asus-wmi.h

@@ -95,6 +95,9 @@
 /* Keyboard dock */
 #define ASUS_WMI_DEVID_KBD_DOCK		0x00120063
 
+/* Charging mode - 1=Barrel, 2=USB */
+#define ASUS_WMI_DEVID_CHARGE_MODE	0x0012006C
+
 /* dgpu on/off */
 #define ASUS_WMI_DEVID_EGPU		0x00090019