battery: optionally use capacity_level for determining battery state

Requires upower with a patch to expose capacity_level on sysfs [0]. The
functionality is enabled in the config file. It is additionally possible to
configure mce to consider the battery as completely empty when capacity_level
reports "Low".

[0] https://gitlab.freedesktop.org/upower/upower/-/merge_requests/259

Author: sicelo

config/mce.ini

@@ -312,6 +312,13 @@ PatternUserManual=9;1;0;1;0;0;0;0;0
 # Percentage at wich the battery is considerd "low" and a warning appears
 LowPercentage=10
 
+# Enable this to use capacity_level from sysfs for shutdown policy
+UseCapacityLevel=false
+
+# When UseCapacityLevel = true, enable this to consider battery as empty when
+# capacity_level is "low" instead of "critical"
+CapacityLevelLowCritical=false
+
 [Display]
 
 # Time in seconds between the display going dim and it turning off entirely

src/modules/battery-upower.c

@@ -62,6 +62,8 @@ G_MODULE_EXPORT module_info_struct module_info = {
 #define MCE_CONF_BATTERY_SECTION "Battery"
 #define MCE_CONF_CRIT_VOLTAGE_KEY "CriticalVoltage"
 #define MCE_CONF_LOW_PERCENT_KEY "LowPercentage"
+#define MCE_CONF_USE_CAPACITY_LEVEL "UseCapacityLevel"
+#define MCE_CONF_CAPACITY_LOW_CRITICAL_KEY "CapacityLevelLowCritical"
 
 
 /** Skip these devices */
@@ -83,6 +85,8 @@ static struct {
 	time_t    force_state;
 	gdouble min_voltage;
 	int low_percentage;
+	gboolean  use_capacity_level;
+	gboolean  level_low_critical;
 } private = {0};
 
 /** Battery properties available via UPower */
@@ -91,6 +95,7 @@ struct {
 	gdouble  percentage;
 	gdouble  voltage;
 	gboolean charger_online;
+	gchar    *supply_level;
 } upowbat = {0};
 
 /** Battery properties in mce statemachine compatible form */
@@ -113,6 +118,7 @@ upowbat_init(void)
 {
 	upowbat.percentage = 50;
 	upowbat.voltage    = 3.8;
+	upowbat.supply_level = NULL;
 	upowbat.state = UP_DEVICE_STATE_UNKNOWN;
 }
 
@@ -135,6 +141,7 @@ upowbat_update(void)
 	gdouble percentage;
 	gdouble voltage;
 	guint   state;
+	gchar  *supply_level;
 
 	if (private.battery == NULL)
 		return;
@@ -143,6 +150,7 @@ upowbat_update(void)
 				"percentage", &percentage,
 				"state", &state,
 				"voltage", &voltage,
+				"supply-level", &supply_level,
 				NULL);
 
 	if (upowbat.percentage != percentage) {
@@ -164,6 +172,11 @@ upowbat_update(void)
 		}
 	}
 
+	if (g_strcmp0(upowbat.supply_level, supply_level) != 0) {
+		mce_log(LL_DEBUG, "%s: Capacity Level: %s -> %s", MODULE_NAME, upowbat.supply_level, supply_level);
+		upowbat.supply_level = supply_level;
+	}
+
 	if (upowbat.state != state) {
 		if (upowbat.state == UP_DEVICE_STATE_FULLY_CHARGED && state == UP_DEVICE_STATE_CHARGING) {
 			/* Prevent 'fully charged' -> 'charging' transition */
@@ -191,13 +204,21 @@ mcebat_update_from_upowbat(void)
 								upowbat.state == UP_DEVICE_STATE_PENDING_CHARGE;
 	}
 
-	if (upowbat.state == UP_DEVICE_STATE_EMPTY ||
-		upowbat.voltage < private.min_voltage && !mcebat.charger_connected)
-		mcebat.status = BATTERY_STATUS_EMPTY;
-	else if (upowbat.percentage < private.low_percentage)
-		mcebat.status = BATTERY_STATUS_LOW;
-	else if (upowbat.state == UP_DEVICE_STATE_FULLY_CHARGED)
+	if (upowbat.state == UP_DEVICE_STATE_FULLY_CHARGED) {
 		mcebat.status = BATTERY_STATUS_FULL;
+	} else if (private.use_capacity_level) {
+		if (g_strcmp0(upowbat.supply_level, "Critical") == 0 ||
+		    (private.level_low_critical && g_strcmp0(upowbat.supply_level, "Low") == 0))
+			mcebat.status = BATTERY_STATUS_EMPTY;
+		else if (g_strcmp0(upowbat.supply_level, "Low") == 0)
+			mcebat.status = BATTERY_STATUS_LOW;
+	} else {
+		if (upowbat.state == UP_DEVICE_STATE_EMPTY ||
+		    (upowbat.voltage < private.min_voltage && !mcebat.charger_connected))
+			mcebat.status = BATTERY_STATUS_EMPTY;
+		else if (upowbat.percentage < private.low_percentage)
+			mcebat.status = BATTERY_STATUS_LOW;
+	}
 }
 
 static inline const char *
@@ -476,6 +497,10 @@ xup_battery_connect_handlers(void)
 	g_signal_connect(private.battery, "notify::voltage",
 					G_CALLBACK(xup_battery_properties_changed_cb),
 					NULL);
+
+	g_signal_connect(private.battery, "notify::supply-level",
+					G_CALLBACK(xup_battery_properties_changed_cb),
+					NULL);
 }
 
 /**
@@ -639,6 +664,8 @@ const gchar *g_module_check_init(GModule *module)
 	if(private.min_voltage > 0.1)
 		mce_log(LL_INFO, "%s: critical voltage set set to %f", MODULE_NAME, private.min_voltage);
 	private.low_percentage = mce_conf_get_int(MCE_CONF_BATTERY_SECTION, MCE_CONF_LOW_PERCENT_KEY, 5, NULL);
+	private.use_capacity_level = mce_conf_get_bool(MCE_CONF_BATTERY_SECTION, MCE_CONF_USE_CAPACITY_LEVEL, false, NULL);
+	private.level_low_critical = mce_conf_get_bool(MCE_CONF_BATTERY_SECTION, MCE_CONF_CAPACITY_LOW_CRITICAL_KEY, false, NULL);
 
 	/* Find battery/charger devices and add them to private */
 	xup_find_devices();