power: reset: syscon-poweroff: Use devm_register_sys_off_handler(POWER_OFF)

Use device life-cycle managed register function to simplify probe and
exit paths.

This also makes our data struct per-device and not global, which allows
for more than one instance of this device.
Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240212162831.67838-20-afd@ti.comSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/reset/syscon-poweroff.c

@@ -13,6 +13,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
+#include <linux/reboot.h>
 #include <linux/regmap.h>
 
 struct syscon_poweroff_data {
@@ -22,21 +23,24 @@ struct syscon_poweroff_data {
 	u32 mask;
 };
 
-static struct syscon_poweroff_data *data;
-
-static void syscon_poweroff(void)
+static int syscon_poweroff(struct sys_off_data *off_data)
 {
+	struct syscon_poweroff_data *data = off_data->cb_data;
+
 	/* Issue the poweroff */
 	regmap_update_bits(data->map, data->offset, data->mask, data->value);
 
 	mdelay(1000);
 
 	pr_emerg("Unable to poweroff system\n");
+
+	return NOTIFY_DONE;
 }
 
 static int syscon_poweroff_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct syscon_poweroff_data *data;
 	int mask_err, value_err;
 
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
@@ -73,21 +77,10 @@ static int syscon_poweroff_probe(struct platform_device *pdev)
 		data->mask = 0xFFFFFFFF;
 	}
 
-	if (pm_power_off) {
-		dev_err(dev, "pm_power_off already claimed for %ps",
-			pm_power_off);
-		return -EBUSY;
-	}
-
-	pm_power_off = syscon_poweroff;
-
-	return 0;
-}
-
-static void syscon_poweroff_remove(struct platform_device *pdev)
-{
-	if (pm_power_off == syscon_poweroff)
-		pm_power_off = NULL;
+	return devm_register_sys_off_handler(&pdev->dev,
+					     SYS_OFF_MODE_POWER_OFF,
+					     SYS_OFF_PRIO_DEFAULT,
+					     syscon_poweroff, data);
 }
 
 static const struct of_device_id syscon_poweroff_of_match[] = {
@@ -97,7 +90,6 @@ static const struct of_device_id syscon_poweroff_of_match[] = {
 
 static struct platform_driver syscon_poweroff_driver = {
 	.probe = syscon_poweroff_probe,
-	.remove_new = syscon_poweroff_remove,
 	.driver = {
 		.name = "syscon-poweroff",
 		.of_match_table = syscon_poweroff_of_match,