HID: wacom: Remove AES power_supply after extended inactivity

Even if a user does not use their AES pen for an extended period,
the battery power supply attributes continue to exist.
This results in the desktop showing battery status for a pen
that is no longer in use and which may in fact be in a different
state (e.g. the user may be charging the pen).
To avoid confusion and ensure userspace has an accurate view
of the battery state, this patch automatically removes
the power_supply after 30 minutes of inactivity.

Signed-off-by: Tatsunosuke Tobita <[email protected]>
Reviewed-by: Jason Gerecke <[email protected]>
Reviewed-by: Aaron Skomra <[email protected]>
Reviewed-by: Josh Dickens <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Benjamin Tissoires <[email protected]>

Author: flying-elephant

drivers/hid/wacom.h

@@ -164,6 +164,7 @@ struct wacom {
 	struct work_struct battery_work;
 	struct work_struct remote_work;
 	struct delayed_work init_work;
+	struct delayed_work aes_battery_work;
 	struct wacom_remote *remote;
 	struct work_struct mode_change_work;
 	struct timer_list idleprox_timer;

drivers/hid/wacom_sys.c

@@ -1813,6 +1813,13 @@ static void wacom_destroy_battery(struct wacom *wacom)
 	}
 }
 
+static void wacom_aes_battery_handler(struct work_struct *work)
+{
+	struct wacom *wacom = container_of(work, struct wacom, aes_battery_work.work);
+
+	wacom_destroy_battery(wacom);
+}
+
 static ssize_t wacom_show_speed(struct device *dev,
 				struct device_attribute
 				*attr, char *buf)
@@ -2794,6 +2801,7 @@ static int wacom_probe(struct hid_device *hdev,
 
 	mutex_init(&wacom->lock);
 	INIT_DELAYED_WORK(&wacom->init_work, wacom_init_work);
+	INIT_DELAYED_WORK(&wacom->aes_battery_work, wacom_aes_battery_handler);
 	INIT_WORK(&wacom->wireless_work, wacom_wireless_work);
 	INIT_WORK(&wacom->battery_work, wacom_battery_work);
 	INIT_WORK(&wacom->remote_work, wacom_remote_work);

drivers/hid/wacom_wac.c

@@ -2528,11 +2528,12 @@ static void wacom_wac_pen_report(struct hid_device *hdev,
 	struct input_dev *input = wacom_wac->pen_input;
 	bool range = wacom_wac->hid_data.inrange_state;
 	bool sense = wacom_wac->hid_data.sense_state;
+	bool entering_range = !wacom_wac->tool[0] && range;
 
 	if (wacom_wac->is_invalid_bt_frame)
 		return;
 
-	if (!wacom_wac->tool[0] && range) { /* first in range */
+	if (entering_range) { /* first in range */
 		/* Going into range select tool */
 		if (wacom_wac->hid_data.invert_state)
 			wacom_wac->tool[0] = BTN_TOOL_RUBBER;
@@ -2583,6 +2584,15 @@ static void wacom_wac_pen_report(struct hid_device *hdev,
 		input_sync(input);
 	}
 
+	/* Handle AES battery timeout behavior */
+	if (wacom_wac->features.quirks & WACOM_QUIRK_AESPEN) {
+		if (entering_range)
+			cancel_delayed_work(&wacom->aes_battery_work);
+		if (!sense)
+			schedule_delayed_work(&wacom->aes_battery_work,
+					      msecs_to_jiffies(WACOM_AES_BATTERY_TIMEOUT));
+	}
+
 	if (!sense) {
 		wacom_wac->tool[0] = 0;
 		wacom_wac->id[0] = 0;

drivers/hid/wacom_wac.h

@@ -14,6 +14,7 @@
 #define WACOM_MAX_REMOTES	5
 #define WACOM_STATUS_UNKNOWN	255
 #define WACOM_REMOTE_BATTERY_TIMEOUT	21000000000ll
+#define WACOM_AES_BATTERY_TIMEOUT       1800000
 
 /* packet length for individual models */
 #define WACOM_PKGLEN_BBFUN	 9