[PATCH v3 1/3] power: reset: new driver regulator-poweroff

Michael Klein
2020-12-07T14:29:49Z

This driver registers a pm_power_off function to disable a set of
regulators defined in the devicetree to turn off the board.

Signed-off-by: Michael Klein <michael@fossekall.de>
---
drivers/power/reset/Kconfig | 7 ++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/regulator-poweroff.c | 107 +++++++++++++++++++++++
3 files changed, 115 insertions(+)
create mode 100644 drivers/power/reset/regulator-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index d55b3727e00e..ae6cb7b0bd4d 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -177,6 +177,13 @@ config POWER_RESET_QNAP

Say Y if you have a QNAP NAS.

+config POWER_RESET_REGULATOR
+ bool "Regulator subsystem power-off driver"
+ depends on OF && REGULATOR
+ help
+ This driver supports turning off your board by disabling a set
+ of regulators defined in the devicetree.
+
config POWER_RESET_RESTART
bool "Restart power-off driver"
help
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index c51eceba9ea3..9dc49d3a57ff 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
+obj-$(CONFIG_POWER_RESET_REGULATOR) += regulator-poweroff.o
obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
diff --git a/drivers/power/reset/regulator-poweroff.c b/drivers/power/reset/regulator-poweroff.c
new file mode 100644
index 000000000000..df2ca4fdcc49
--- /dev/null
+++ b/drivers/power/reset/regulator-poweroff.c
@@ -0,0 +1,107 @@
+// 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/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#define DEFAULT_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 **poweroff_regulators;
+static u32 timeout = DEFAULT_TIMEOUT_MS;
+
+static void regulator_poweroff_do_poweroff(void)
+{
+ struct regulator **it;
+
+ if (poweroff_regulators)
+ for (it = poweroff_regulators; *it; ++it)
+ if (regulator_is_enabled(*it))
+ regulator_force_disable(*it);
+
+ /* give it some time */
+ mdelay(timeout);
+
+ WARN_ON(1);
+}
+
+static int regulator_poweroff_probe(struct platform_device *pdev)
+{
+ int count;
+ const char *name;
+ struct regulator **it;
+ struct property *prop;
+ struct device_node *node = pdev->dev.of_node;
+
+ /* 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;
+ }
+
+ count = of_property_count_strings(node, "regulator-names");
+ if (count <= 0)
+ return -ENOENT;
+
+ poweroff_regulators = devm_kcalloc(&pdev->dev, count + 1,
+ sizeof(struct regulator *), GFP_KERNEL);
+
+ it = poweroff_regulators;
+ of_property_for_each_string(node, "regulator-names", prop, name) {
+ *it = devm_regulator_get(&pdev->dev, name);
+ if (IS_ERR(*it))
+ return PTR_ERR(*it);
+ it++;
+ }
+
+ of_property_read_u32(node, "timeout-ms", &timeout);
+
+ 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", },
+ {},
+};
+
+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_LICENSE("GPL v2");
+MODULE_ALIAS("platform:poweroff-regulator");
--
2.29.2