mfd: tps6586x: Use devm-based power off handler

Convert the power off handler to a devm-based power off handler.
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-4-18699d5dcd76@skidata.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/tps6586x.c

@@ -22,6 +22,7 @@
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/regmap.h>
 #include <linux/of.h>
 
@@ -457,13 +458,21 @@ static const struct regmap_config tps6586x_regmap_config = {
 	.cache_type = REGCACHE_RBTREE,
 };
 
-static struct device *tps6586x_dev;
-static void tps6586x_power_off(void)
+static int tps6586x_power_off_handler(struct sys_off_data *data)
 {
-	if (tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT))
-		return;
+	int ret;
+
+	/* Put the PMIC into sleep state. This takes at least 20ms. */
+	ret = tps6586x_clr_bits(data->dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT);
+	if (ret)
+		return notifier_from_errno(ret);
+
+	ret = tps6586x_set_bits(data->dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);
+	if (ret)
+		return notifier_from_errno(ret);
 
-	tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);
+	mdelay(50);
+	return notifier_from_errno(-ETIME);
 }
 
 static void tps6586x_print_version(struct i2c_client *client, int version)
@@ -559,9 +568,13 @@ static int tps6586x_i2c_probe(struct i2c_client *client)
 		goto err_add_devs;
 	}
 
-	if (pdata->pm_off && !pm_power_off) {
-		tps6586x_dev = &client->dev;
-		pm_power_off = tps6586x_power_off;
+	if (pdata->pm_off) {
+		ret = devm_register_power_off_handler(&client->dev, &tps6586x_power_off_handler,
+						      NULL);
+		if (ret) {
+			dev_err(&client->dev, "register power off handler failed: %d\n", ret);
+			goto err_add_devs;
+		}
 	}
 
 	return 0;