HID: wacom: Add ability to provide explicit battery status info

At the moment, our driver relies on 'wacom_battery_get_property()' to
determine the most likely battery state (e.g charging, discharging, or
full) based on the information available. It is not always possible
for the function to properly determine this, however. For instance,
whenever an AES pen leaves proximity the battery state becomes
indeterminite. This commit adds the ability to provide it with explict
state information if desired. Whenever explicit state is not required
(the majority of circumstances), WACOM_POWER_SUPPLY_STATUS_AUTO can
be used in its place.

Three uses of explicit battery status are added: two wireless disconnect
paths and the AES case mentioned above.

Signed-off-by: Jason Gerecke <[e-mail]>
Reviewed-by: Ping Cheng <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/wacom.h

···
 	struct power_supply_desc bat_desc;
 	struct power_supply *battery;
 	char bat_name[WACOM_NAME_MAX];
+	int bat_status;
 	int battery_capacity;
 	int bat_charging;
 	int bat_connected;

drivers/hid/wacom_sys.c

···
 			val->intval = battery->battery_capacity;
 			break;
 		case POWER_SUPPLY_PROP_STATUS:
-			if (battery->bat_charging)
+			if (battery->bat_status != WACOM_POWER_SUPPLY_STATUS_AUTO)
+				val->intval = battery->bat_status;
+			else if (battery->bat_charging)
 				val->intval = POWER_SUPPLY_STATUS_CHARGING;
 			else if (battery->battery_capacity == 100 &&
 				    battery->ps_connected)

drivers/hid/wacom_wac.c

···
 static unsigned short batcap_i4[8] = { 1, 15, 30, 45, 60, 70, 85, 100 };
 
 static void __wacom_notify_battery(struct wacom_battery *battery,
-				   int bat_capacity, bool bat_charging,
-				   bool bat_connected, bool ps_connected)
+				   int bat_status, int bat_capacity,
+				   bool bat_charging, bool bat_connected,
+				   bool ps_connected)
 {
-	bool changed = battery->battery_capacity != bat_capacity  ||
+	bool changed = battery->bat_status       != bat_status    ||
+		       battery->battery_capacity != bat_capacity  ||
 		       battery->bat_charging     != bat_charging  ||
 		       battery->bat_connected    != bat_connected ||
 		       battery->ps_connected     != ps_connected;
 
 	if (changed) {
+		battery->bat_status = bat_status;
 		battery->battery_capacity = bat_capacity;
 		battery->bat_charging = bat_charging;
 		battery->bat_connected = bat_connected;
···
 }
 
 static void wacom_notify_battery(struct wacom_wac *wacom_wac,
-	int bat_capacity, bool bat_charging, bool bat_connected,
-	bool ps_connected)
+	int bat_status, int bat_capacity, bool bat_charging,
+	bool bat_connected, bool ps_connected)
 {
 	struct wacom *wacom = container_of(wacom_wac, struct wacom, wacom_wac);
 
-	__wacom_notify_battery(&wacom->battery, bat_capacity, bat_charging,
-			       bat_connected, ps_connected);
+	__wacom_notify_battery(&wacom->battery, bat_status, bat_capacity,
+			       bat_charging, bat_connected, ps_connected);
 }
 
 static int wacom_penpartner_irq(struct wacom_wac *wacom)
···
 		rw = (data[7] >> 2 & 0x07);
 		battery_capacity = batcap_gr[rw];
 		ps_connected = rw == 7;
-		wacom_notify_battery(wacom, battery_capacity, ps_connected,
-				     1, ps_connected);
+		wacom_notify_battery(wacom, WACOM_POWER_SUPPLY_STATUS_AUTO,
+				     battery_capacity, ps_connected, 1,
+				     ps_connected);
 	}
 exit:
 	return retval;
···
 			wacom->led.groups[i].select = touch_ring_mode;
 	}
 
-	__wacom_notify_battery(&remote->remotes[index].battery, bat_percent,
+	__wacom_notify_battery(&remote->remotes[index].battery,
+				WACOM_POWER_SUPPLY_STATUS_AUTO, bat_percent,
 				bat_charging, 1, bat_charging);
 
 out:
···
 		bat_charging = (power_raw & 0x08) ? 1 : 0;
 		ps_connected = (power_raw & 0x10) ? 1 : 0;
 		battery_capacity = batcap_i4[power_raw & 0x07];
-		wacom_notify_battery(wacom, battery_capacity, bat_charging,
+		wacom_notify_battery(wacom, WACOM_POWER_SUPPLY_STATUS_AUTO,
+				     battery_capacity, bat_charging,
 				     battery_capacity || bat_charging,
 				     ps_connected);
 		break;
···
 	bool chg = data[284] & 0x80;
 	int battery_status = data[284] & 0x7F;
 
-	wacom_notify_battery(wacom, battery_status, chg, 1, chg);
+	wacom_notify_battery(wacom, WACOM_POWER_SUPPLY_STATUS_AUTO,
+			     battery_status, chg, 1, chg);
 }
 
 static int wacom_intuos_pro2_bt_irq(struct wacom_wac *wacom, size_t len)
···
 		value = value * 100 / (field->logical_maximum - field->logical_minimum);
 		wacom_wac->hid_data.battery_capacity = value;
 		wacom_wac->hid_data.bat_connected = 1;
+		wacom_wac->hid_data.bat_status = WACOM_POWER_SUPPLY_STATUS_AUTO;
 		break;
 
 	case WACOM_HID_WD_BATTERY_CHARGING:
···
 	struct wacom_features *features = &wacom_wac->features;
 
 	if (features->quirks & WACOM_QUIRK_BATTERY) {
+		int status = wacom_wac->hid_data.bat_status;
 		int capacity = wacom_wac->hid_data.battery_capacity;
 		bool charging = wacom_wac->hid_data.bat_charging;
 		bool connected = wacom_wac->hid_data.bat_connected;
 		bool powered = wacom_wac->hid_data.ps_connected;
 
-		wacom_notify_battery(wacom_wac, capacity, charging,
-				     connected, powered);
+		wacom_notify_battery(wacom_wac, status, capacity,
+				     charging, connected, powered);
 	}
 }
 
···
 			wacom_wac->hid_data.sense_state = value;
 		return;
 	case HID_DG_BATTERYSTRENGTH:
-		if (value == 0) /* "not available" */
-			break;
-		value = value * 100 / (field->logical_maximum - field->logical_minimum);
-		wacom_wac->hid_data.battery_capacity = value;
-		wacom_wac->hid_data.bat_connected = 1;
+		if (value == 0) {
+			wacom_wac->hid_data.bat_status = POWER_SUPPLY_STATUS_UNKNOWN;
+		}
+		else {
+			value = value * 100 / (field->logical_maximum - field->logical_minimum);
+			wacom_wac->hid_data.battery_capacity = value;
+			wacom_wac->hid_data.bat_connected = 1;
+			wacom_wac->hid_data.bat_status = WACOM_POWER_SUPPLY_STATUS_AUTO;
+		}
 		break;
 	case HID_DG_INVERT:
 		wacom_wac->hid_data.invert_state = value;
···
 			wacom_schedule_work(wacom, WACOM_WORKER_WIRELESS);
 		}
 
-		wacom_notify_battery(wacom, battery, charging, 1, 0);
+		wacom_notify_battery(wacom, WACOM_POWER_SUPPLY_STATUS_AUTO,
+				     battery, charging, 1, 0);
 
 	} else if (wacom->pid != 0) {
 		/* disconnected while previously connected */
 		wacom->pid = 0;
 		wacom_schedule_work(wacom, WACOM_WORKER_WIRELESS);
-		wacom_notify_battery(wacom, 0, 0, 0, 0);
+		wacom_notify_battery(wacom, POWER_SUPPLY_STATUS_UNKNOWN, 0, 0, 0, 0);
 	}
 
 	return 0;
···
 		int battery = (data[8] & 0x3f) * 100 / 31;
 		bool charging = !!(data[8] & 0x80);
 
-		wacom_notify_battery(wacom_wac, battery, charging,
-				     battery || charging, 1);
+		wacom_notify_battery(wacom_wac, WACOM_POWER_SUPPLY_STATUS_AUTO,
+				     battery, charging, battery || charging, 1);
 
 		if (!wacom->battery.battery &&
 		    !(features->quirks & WACOM_QUIRK_BATTERY)) {
···
 		 wacom->battery.battery) {
 		features->quirks &= ~WACOM_QUIRK_BATTERY;
 		wacom_schedule_work(wacom_wac, WACOM_WORKER_BATTERY);
-		wacom_notify_battery(wacom_wac, 0, 0, 0, 0);
+		wacom_notify_battery(wacom_wac, POWER_SUPPLY_STATUS_UNKNOWN, 0, 0, 0, 0);
 	}
 	return 0;
 }

drivers/hid/wacom_wac.h

···
 #define WACOM_DEVICETYPE_WL_MONITOR     0x0008
 #define WACOM_DEVICETYPE_DIRECT         0x0010
 
+#define WACOM_POWER_SUPPLY_STATUS_AUTO  -1
+
 #define WACOM_HID_UP_WACOMDIGITIZER     0xff0d0000
 #define WACOM_HID_SP_PAD                0x00040000
 #define WACOM_HID_SP_BUTTON             0x00090000
···
 	int last_slot_field;
 	int num_expected;
 	int num_received;
+	int bat_status;
 	int battery_capacity;
 	int bat_charging;
 	int bat_connected;