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

Maxime Ripard
2020-12-08T10:12:19Z

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On Mon, Dec 07, 2020 at 03:27:54PM +0100, Michael Klein wrote:
> 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);

Since this can't be compiled as a module, you can use
module_platform_driver_probe instead.

Maxime

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