1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/power/reset/regulator-poweroff.c b/drivers/power/reset/regulator-poweroff.c
new file mode 100644
index 0000000000..7f87fbb8b0
--- /dev/null
+++ b/drivers/power/reset/regulator-poweroff.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Force-disables a regulator to power down a device
+ *
+ * Michael Klein <michael@fossekall.de>
+ *
+ * Copyright (C) 2020 Michael Klein
+ *
+ * Based on the gpio-poweroff driver.
+ */
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+#define TIMEOUT_MS 3000
+
+/*
+ * Hold configuration here, cannot be more than one instance of the driver
+ * since pm_power_off itself is global.
+ */
+static struct regulator *cpu_regulator;
+
+static void regulator_poweroff_do_poweroff(void)
+{
+	if (cpu_regulator && regulator_is_enabled(cpu_regulator))
+		regulator_force_disable(cpu_regulator);
+
+	/* give it some time */
+	mdelay(TIMEOUT_MS);
+
+	WARN_ON(1);
+}
+
+static int regulator_poweroff_probe(struct platform_device *pdev)
+{
+	/* If a pm_power_off function has already been added, leave it alone */
+	if (pm_power_off != NULL) {
+		dev_err(&pdev->dev,
+			"%s: pm_power_off function already registered\n",
+			__func__);
+		return -EBUSY;
+	}
+
+	cpu_regulator = devm_regulator_get(&pdev->dev, "cpu");
+	if (IS_ERR(cpu_regulator))
+		return PTR_ERR(cpu_regulator);
+
+	pm_power_off = &regulator_poweroff_do_poweroff;
+	return 0;
+}
+
+static int regulator_poweroff_remove(__maybe_unused struct platform_device *pdev)
+{
+	if (pm_power_off == &regulator_poweroff_do_poweroff)
+		pm_power_off = NULL;
+
+	return 0;
+}
+
+static const struct of_device_id of_regulator_poweroff_match[] = {
+	{ .compatible = "regulator-poweroff", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match);
+
+static struct platform_driver regulator_poweroff_driver = {
+	.probe = regulator_poweroff_probe,
+	.remove = regulator_poweroff_remove,
+	.driver = {
+		.name = "poweroff-regulator",
+		.of_match_table = of_regulator_poweroff_match,
+	},
+};
+
+module_platform_driver(regulator_poweroff_driver);
+
+MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
+MODULE_DESCRIPTION("Regulator poweroff driver");
+MODULE_ALIAS("platform:poweroff-regulator");