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path: root/drivers/power/reset/regulator-poweroff.c
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Diffstat (limited to 'drivers/power/reset/regulator-poweroff.c')
-rw-r--r--drivers/power/reset/regulator-poweroff.c82
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");