greybus: power_supply: Add runtime pm support

Modify Power_supply greybus driver to support runtime PM framework.

During charging state, the driver will block remote device of suspending,
and then enables runtime suspend when remote device is in none chargin
state.

Testing Done: Compiled and verified on EVT2, EVT2 1x2 GPB test module
and Device class daughter board.

Signed-off-by: Philip Yang <[e-mail]>
Reviewed-by: Rui Miguel Silva <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/greybus/power_supply.c

···
 	bool				changed;
 	struct gb_power_supply_prop	*props;
 	enum power_supply_property	*props_raw;
+	bool				pm_acquired;
+	struct mutex			supply_lock;
 };
 
 struct gb_power_supplies {
···
 			     struct gb_power_supply_prop *prop);
 };
 
+static void gb_power_supply_state_change(struct gb_power_supply *gbpsy,
+					 struct gb_power_supply_prop *prop);
+
 static const struct gb_power_supply_changes psy_props_changes[] = {
 	{	.prop			= GB_POWER_SUPPLY_PROP_STATUS,
 		.tolerance_change	= 0,
-		.prop_changed		= NULL,
+		.prop_changed		= gb_power_supply_state_change,
 	},
 	{	.prop			= GB_POWER_SUPPLY_PROP_TEMP,
 		.tolerance_change	= 500,
···
 	power_supply_changed(gbpsy->psy);
 }
 #endif
+
+static void gb_power_supply_state_change(struct gb_power_supply *gbpsy,
+					 struct gb_power_supply_prop *prop)
+{
+	struct gb_connection *connection = get_conn_from_psy(gbpsy);
+	int ret;
+
+	/*
+	 * Check gbpsy->pm_acquired to make sure only one pair of 'get_sync'
+	 * and 'put_autosuspend' runtime pm call for state property change.
+	 */
+	mutex_lock(&gbpsy->supply_lock);
+
+	if ((prop->val == GB_POWER_SUPPLY_STATUS_CHARGING) &&
+	    !gbpsy->pm_acquired) {
+		ret = gb_pm_runtime_get_sync(connection->bundle);
+		if (ret)
+			dev_err(&connection->bundle->dev,
+				"Fail to set wake lock for charging state\n");
+		else
+			gbpsy->pm_acquired = true;
+	} else {
+		if (gbpsy->pm_acquired) {
+			ret = gb_pm_runtime_put_autosuspend(connection->bundle);
+			if (ret)
+				dev_err(&connection->bundle->dev,
+					"Fail to set wake unlock for none charging\n");
+			else
+				gbpsy->pm_acquired = false;
+		}
+	}
+
+	mutex_unlock(&gbpsy->supply_lock);
+}
 
 static void check_changed(struct gb_power_supply *gbpsy,
 			  struct gb_power_supply_prop *prop)
···
 
 static int gb_power_supply_status_get(struct gb_power_supply *gbpsy)
 {
+	struct gb_connection *connection = get_conn_from_psy(gbpsy);
 	int ret = 0;
 	int i;
 
 	if (is_cache_valid(gbpsy))
 		return 0;
+
+	ret = gb_pm_runtime_get_sync(connection->bundle);
+	if (ret)
+		return ret;
 
 	for (i = 0; i < gbpsy->properties_count; i++) {
 		ret = __gb_power_supply_property_update(gbpsy,
···
 	if (ret == 0)
 		gbpsy->last_update = jiffies;
 
+	gb_pm_runtime_put_autosuspend(connection->bundle);
 	return ret;
 }
 
···
 	struct gb_power_supply_set_property_request req;
 	int ret;
 
+	ret = gb_pm_runtime_get_sync(connection->bundle);
+	if (ret)
+		return ret;
+
 	prop = get_psy_prop(gbpsy, psp);
-	if (!prop)
-		return -EINVAL;
+	if (!prop) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	req.psy_id = gbpsy->id;
 	req.property = prop->gb_prop;
 	req.prop_val = cpu_to_le32((s32)val);
···
 	prop->val = val;
 
 out:
+	gb_pm_runtime_put_autosuspend(connection->bundle);
 	return ret;
 }
 
···
 					  sizeof(gbpsy->name));
 	if (ret < 0)
 		return ret;
+
+	mutex_init(&gbpsy->supply_lock);
 
 	ret = gb_power_supply_register(gbpsy);
 	if (ret < 0)
···
 	if (ret < 0)
 		goto error_connection_disable;
 
+	gb_pm_runtime_put_autosuspend(bundle);
 	return 0;
 
 error_connection_disable: