Re: [PATCH v4 1/2] driver: reset: spacemit-p1: add driver for poweroff/reboot

[Troy Mitchell <troy.mitchell@linux.spacemit.com>]

On Sun, Oct 26, 2025 at 11:41:14PM +0100, Aurelien Jarno wrote:
> This driver implements poweroff/reboot support for the SpacemiT P1 PMIC
> chip, which is commonly paired with the SpacemiT K1 SoC.
> 
> The SpacemiT P1 support is implemented as a MFD driver, so the access is
> done directly through the regmap interface. Reboot or poweroff is
> triggered by setting a specific bit in a control register, which is
> automatically cleared by the hardware afterwards.
> 
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
> v2:
>  - Replace the "select" by a "depends on"
>  - Remove outdated Reviewed-by
> 
>  drivers/power/reset/Kconfig              |  9 +++
>  drivers/power/reset/Makefile             |  1 +
>  drivers/power/reset/spacemit-p1-reboot.c | 88 ++++++++++++++++++++++++
>  3 files changed, 98 insertions(+)
>  create mode 100644 drivers/power/reset/spacemit-p1-reboot.c
> 
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 8248895ca9038..61c16f3d5abc7 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -283,6 +283,15 @@ config POWER_RESET_KEYSTONE
>  	help
>  	  Reboot support for the KEYSTONE SoCs.
>  
> +config POWER_RESET_SPACEMIT_P1
> +	tristate "SpacemiT P1 poweroff and reset driver"
> +	depends on ARCH_SPACEMIT || COMPILE_TEST
> +	depends on MFD_SPACEMIT_P1
> +	default m
default m if ARCH_SPACEMIT? Or default ARCH_SPACEMIT?
I believe that reboot and shutdown are actually essential functionalities,
so it might make more sense: default ARCH_SPACEMIT?

                                      - Troy
> +	help
> +	  This driver supports power-off and reset operations for the SpacemiT
> +	  P1 PMIC.
> +
>  config POWER_RESET_SYSCON
>  	bool "Generic SYSCON regmap reset driver"
>  	depends on OF
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index 51da87e05ce76..0e4ae6f6b5c55 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -24,6 +24,7 @@ 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-$(CONFIG_POWER_RESET_SPACEMIT_P1) += spacemit-p1-reboot.o
>  obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
>  obj-$(CONFIG_POWER_RESET_TH1520_AON) += th1520-aon-reboot.o
>  obj-$(CONFIG_POWER_RESET_TORADEX_EC) += tdx-ec-poweroff.o
> diff --git a/drivers/power/reset/spacemit-p1-reboot.c b/drivers/power/reset/spacemit-p1-reboot.c
> new file mode 100644
> index 0000000000000..9ec3d1fff8f3d
> --- /dev/null
> +++ b/drivers/power/reset/spacemit-p1-reboot.c
> @@ -0,0 +1,88 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2025 by Aurelien Jarno
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/reboot.h>
> +
> +/* Power Control Register 2 */
> +#define PWR_CTRL2		0x7e
> +#define PWR_CTRL2_SHUTDOWN	BIT(2)	/* Shutdown request */
> +#define PWR_CTRL2_RST		BIT(1)	/* Reset request */
> +
> +static int spacemit_p1_pwroff_handler(struct sys_off_data *data)
> +{
> +	struct regmap *regmap = data->cb_data;
> +	int ret;
> +
> +	/* Put the PMIC into shutdown state */
> +	ret = regmap_set_bits(regmap, PWR_CTRL2, PWR_CTRL2_SHUTDOWN);
> +	if (ret) {
> +		dev_err(data->dev, "shutdown failed: %d\n", ret);
> +		return notifier_from_errno(ret);
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int spacemit_p1_restart_handler(struct sys_off_data *data)
> +{
> +	struct regmap *regmap = data->cb_data;
> +	int ret;
> +
> +	/* Put the PMIC into reset state */
> +	ret = regmap_set_bits(regmap, PWR_CTRL2, PWR_CTRL2_RST);
> +	if (ret) {
> +		dev_err(data->dev, "restart failed: %d\n", ret);
> +		return notifier_from_errno(ret);
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int spacemit_p1_reboot_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!regmap)
> +		return -ENODEV;
> +
> +	ret = devm_register_power_off_handler(dev, &spacemit_p1_pwroff_handler,
> +					      regmap);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to register power off handler\n");
> +
> +	ret = devm_register_restart_handler(dev, spacemit_p1_restart_handler,
> +					    regmap);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to register restart handler\n");
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id spacemit_p1_reboot_id_table[] = {
> +	{ "spacemit-p1-reboot", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(platform, spacemit_p1_reboot_id_table);
> +
> +static struct platform_driver spacemit_p1_reboot_driver = {
> +	.driver = {
> +		.name = "spacemit-p1-reboot",
> +	},
> +	.probe = spacemit_p1_reboot_probe,
> +	.id_table = spacemit_p1_reboot_id_table,
> +};
> +module_platform_driver(spacemit_p1_reboot_driver);
> +
> +MODULE_DESCRIPTION("SpacemiT P1 reboot/poweroff driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.47.2
> 
> 

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