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    Subject[PATCH v5 1/3] power: reset: new driver regulator-poweroff
    Date
    This driver registers a pm_power_off function to turn off the board
    by force-disabling a devicetree-defined regulator.

    Signed-off-by: Michael Klein <michael@fossekall.de>
    ---
    drivers/power/reset/Kconfig | 7 ++
    drivers/power/reset/Makefile | 1 +
    drivers/power/reset/regulator-poweroff.c | 82 ++++++++++++++++++++++++
    3 files changed, 90 insertions(+)
    create mode 100644 drivers/power/reset/regulator-poweroff.c

    diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
    index d55b3727e00e..b22c4fdb2561 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
    + power regulator 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..f697088e0ad1
    --- /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", },
    + {},
    +};
    +
    +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
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