mfd: max77620: Provide system power-off functionality

Provide system power-off functionality that allows to turn off machine
gracefully.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/max77620.c

@@ -37,6 +37,8 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 
+static struct max77620_chip *max77620_scratch;
+
 static const struct resource gpio_resources[] = {
 	DEFINE_RES_IRQ(MAX77620_IRQ_TOP_GPIO),
 };
@@ -481,6 +483,15 @@ static int max77620_read_es_version(struct max77620_chip *chip)
 	return ret;
 }
 
+static void max77620_pm_power_off(void)
+{
+	struct max77620_chip *chip = max77620_scratch;
+
+	regmap_update_bits(chip->rmap, MAX77620_REG_ONOFFCNFG1,
+			   MAX77620_ONOFFCNFG1_SFT_RST,
+			   MAX77620_ONOFFCNFG1_SFT_RST);
+}
+
 static int max77620_probe(struct i2c_client *client,
 			  const struct i2c_device_id *id)
 {
@@ -488,6 +499,7 @@ static int max77620_probe(struct i2c_client *client,
 	struct max77620_chip *chip;
 	const struct mfd_cell *mfd_cells;
 	int n_mfd_cells;
+	bool pm_off;
 	int ret;
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
@@ -554,6 +566,12 @@ static int max77620_probe(struct i2c_client *client,
 		return ret;
 	}
 
+	pm_off = of_device_is_system_power_controller(client->dev.of_node);
+	if (pm_off && !pm_power_off) {
+		max77620_scratch = chip;
+		pm_power_off = max77620_pm_power_off;
+	}
+
 	return 0;
 }