asus-wmi: Add panel overdrive functionality

Some ASUS ROG laptops have the ability to drive the display panel
a higher rate to eliminate or reduce ghosting.
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20210807023656.25020-2-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

@@ -216,6 +216,9 @@ struct asus_wmi {
 	// The RSOC controls the maximum charging percentage.
 	bool battery_rsoc_available;
 
+	bool panel_overdrive_available;
+	bool panel_overdrive;
+
 	struct hotplug_slot hotplug_slot;
 	struct mutex hotplug_lock;
 	struct mutex wmi_lock;
@@ -1221,6 +1224,87 @@ static int asus_wmi_rfkill_init(struct asus_wmi *asus)
 	return result;
 }
 
+/* Panel Overdrive ************************************************************/
+static int panel_od_check_present(struct asus_wmi *asus)
+{
+	u32 result;
+	int err;
+
+	asus->panel_overdrive_available = false;
+
+	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_PANEL_OD, &result);
+	if (err) {
+		if (err == -ENODEV)
+			return 0;
+		return err;
+	}
+
+	if (result & ASUS_WMI_DSTS_PRESENCE_BIT) {
+		asus->panel_overdrive_available = true;
+		asus->panel_overdrive = result & ASUS_WMI_DSTS_STATUS_BIT;
+	}
+
+	return 0;
+}
+
+static int panel_od_write(struct asus_wmi *asus)
+{
+	u32 retval;
+	u8 value;
+	int err;
+
+	/* Don't rely on type conversion */
+	value = asus->panel_overdrive ? 1 : 0;
+
+	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_PANEL_OD, value, &retval);
+
+	if (err) {
+		pr_warn("Failed to set panel overdrive: %d\n", err);
+		return err;
+	}
+
+	if (retval > 1 || retval < 0) {
+		pr_warn("Failed to set panel overdrive (retval): 0x%x\n", retval);
+		return -EIO;
+	}
+
+	sysfs_notify(&asus->platform_device->dev.kobj, NULL, "panel_od");
+
+	return 0;
+}
+
+static ssize_t panel_od_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", asus->panel_overdrive);
+}
+
+static ssize_t panel_od_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	bool overdrive;
+	int result;
+
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+
+	result = kstrtobool(buf, &overdrive);
+	if (result)
+		return result;
+
+	asus->panel_overdrive = overdrive;
+	result = panel_od_write(asus);
+
+	if (result)
+		return result;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(panel_od);
+
 /* Quirks *********************************************************************/
 
 static void asus_wmi_set_xusb2pr(struct asus_wmi *asus)
@@ -2332,6 +2416,7 @@ static struct attribute *platform_attributes[] = {
 	&dev_attr_als_enable.attr,
 	&dev_attr_fan_boost_mode.attr,
 	&dev_attr_throttle_thermal_policy.attr,
+	&dev_attr_panel_od.attr,
 	NULL
 };
 
@@ -2357,6 +2442,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
 		ok = asus->fan_boost_mode_available;
 	else if (attr == &dev_attr_throttle_thermal_policy.attr)
 		ok = asus->throttle_thermal_policy_available;
+	else if (attr == &dev_attr_panel_od.attr)
+		ok = asus->panel_overdrive_available;
 
 	if (devid != -1)
 		ok = !(asus_wmi_get_devstate_simple(asus, devid) < 0);
@@ -2622,6 +2709,10 @@ static int asus_wmi_add(struct platform_device *pdev)
 	else
 		throttle_thermal_policy_set_default(asus);
 
+	err = panel_od_check_present(asus);
+	if (err)
+		goto fail_panel_od;
+
 	err = asus_wmi_sysfs_init(asus->platform_device);
 	if (err)
 		goto fail_sysfs;
@@ -2709,6 +2800,7 @@ static int asus_wmi_add(struct platform_device *pdev)
 fail_throttle_thermal_policy:
 fail_fan_boost_mode:
 fail_platform:
+fail_panel_od:
 	kfree(asus);
 	return err;
 }

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

@@ -61,6 +61,7 @@
 #define ASUS_WMI_DEVID_THROTTLE_THERMAL_POLICY 0x00120075
 
 /* Misc */
+#define ASUS_WMI_DEVID_PANEL_OD		0x00050019
 #define ASUS_WMI_DEVID_CAMERA		0x00060013
 #define ASUS_WMI_DEVID_LID_FLIP		0x00060062