Re: [PATCH v5 07/10] power: reset: macsmc-reboot: Add driver for rebooting via Apple SMC

[Stefan Wahren]

Hi Sven,

Am 11.05.25 um 10:18 schrieb Sven Peter via B4 Relay:
> From: Hector Martin <marcan@xxxxxxxxx>
>
> This driver implements the reboot/shutdown support exposed by the SMC
> on Apple Silicon machines, such as Apple M1 Macs.
>
> Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
> Signed-off-by: Sven Peter <sven@xxxxxxxxxxxxx>
> ---
>   MAINTAINERS                         |   1 +
>   drivers/power/reset/Kconfig         |  11 ++
>   drivers/power/reset/Makefile        |   1 +
>   drivers/power/reset/macsmc-reboot.c | 363 ++++++++++++++++++++++++++++++++++++
>   4 files changed, 376 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fa3a5f9ee40446bcc725c9eac2a36651e6bc7553..84f7a730eb2260b7c1e0487d18c8eb3de82f5206 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2303,6 +2303,7 @@ F:	drivers/mfd/macsmc.c
>   F:	drivers/nvme/host/apple.c
>   F:	drivers/nvmem/apple-efuses.c
>   F:	drivers/pinctrl/pinctrl-apple-gpio.c
> +F:	drivers/power/reset/macsmc-reboot.c
>   F:	drivers/pwm/pwm-apple.c
>   F:	drivers/soc/apple/*
>   F:	drivers/spi/spi-apple.c
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 60bf0ca64cf395cd18238fc626611c74d29844ee..6e8dfff64fdc001d09b6c00630cd8b7e2fafdd8e 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -128,6 +128,17 @@ config POWER_RESET_LINKSTATION
>   
>   	  Say Y here if you have a Buffalo LinkStation LS421D/E.
>   
> +config POWER_RESET_MACSMC
> +	tristate "Apple SMC reset/power-off driver"
> +	depends on ARCH_APPLE || COMPILE_TEST
> +	depends on MFD_MACSMC
> +	depends on OF
> +	help
> +	  This driver supports reset and power-off on Apple Mac machines
> +	  that implement this functionality via the SMC.
> +
> +	  Say Y here if you have an Apple Silicon Mac.
> +
>   config POWER_RESET_MSM
>   	bool "Qualcomm MSM power-off driver"
>   	depends on ARCH_QCOM
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index 10782d32e1da39f4b8b4566e8a885f2e13f65130..887dd9e49b7293b69b9429ddc0c1571194a153cf 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
>   obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
>   obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
>   obj-$(CONFIG_POWER_RESET_LINKSTATION) += linkstation-poweroff.o
> +obj-$(CONFIG_POWER_RESET_MACSMC) += macsmc-reboot.o
>   obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
>   obj-$(CONFIG_POWER_RESET_MT6323) += mt6323-poweroff.o
>   obj-$(CONFIG_POWER_RESET_QCOM_PON) += qcom-pon.o
> diff --git a/drivers/power/reset/macsmc-reboot.c b/drivers/power/reset/macsmc-reboot.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..d82339e427886667be4ad2de0d1d5c04d2383059
> --- /dev/null
> +++ b/drivers/power/reset/macsmc-reboot.c
> @@ -0,0 +1,363 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC Reboot/Poweroff Handler
> + * Copyright The Asahi Linux Contributors
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/macsmc.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/slab.h>
> +
> +struct macsmc_reboot_nvmem {
> +	struct nvmem_cell *shutdown_flag;
> +	struct nvmem_cell *pm_setting;
> +	struct nvmem_cell *boot_stage;
> +	struct nvmem_cell *boot_error_count;
> +	struct nvmem_cell *panic_count;
> +};
> +
> +static const char * const nvmem_names[] = {
> +	"shutdown_flag",
> +	"pm_setting",
> +	"boot_stage",
> +	"boot_error_count",
> +	"panic_count",
> +};
> +
> +enum boot_stage {
> +	BOOT_STAGE_SHUTDOWN		= 0x00, /* Clean shutdown */
> +	BOOT_STAGE_IBOOT_DONE		= 0x2f, /* Last stage of bootloader */
> +	BOOT_STAGE_KERNEL_STARTED	= 0x30, /* Normal OS booting */
> +};
> +
> +enum pm_setting {
> +	PM_SETTING_AC_POWER_RESTORE	= 0x02,
> +	PM_SETTING_AC_POWER_OFF		= 0x03,
> +};
> +
> +static const char * const ac_power_modes[] = { "off", "restore" };
> +
> +static int ac_power_mode_map[] = {
> +	PM_SETTING_AC_POWER_OFF,
> +	PM_SETTING_AC_POWER_RESTORE,
> +};
> +
> +struct macsmc_reboot {
> +	struct device *dev;
> +	struct apple_smc *smc;
> +	struct notifier_block reboot_notify;
> +
> +	union {
> +		struct macsmc_reboot_nvmem nvm;
> +		struct nvmem_cell *nvm_cells[ARRAY_SIZE(nvmem_names)];
> +	};
> +};
> +
> +/* Helpers to read/write a u8 given a struct nvmem_cell */
> +static int nvmem_cell_get_u8(struct nvmem_cell *cell)
> +{
> +	size_t len;
> +	u8 val;
> +	void *ret = nvmem_cell_read(cell, &len);
in case this series needs a respin, please rename the pointer (e.g. 
buf). This is very unusual, because ret is usually of type int.

Regards