Re: [PATCH v3 08/13] input: macsmc-input: New driver to handle the Apple Mac SMC buttons/lid

[Janne Grunau <j@jannau.net>]

On Tue, Oct 07, 2025 at 09:16:49PM +1000, James Calligeros wrote:
> From: Hector Martin <marcan@marcan.st>
> 
> This driver implements power button and lid switch support for Apple Mac
> devices using SMC controllers driven by the macsmc driver.
> 
> In addition to basic input support, this also responds to the final
> shutdown warning (when the power button is held down long enough) by
> doing an emergency kernel poweroff. This allows the NVMe controller to
> be cleanly shut down, which prevents data loss for in-cache data.
> 
> Reviewed-by: Neal Gompa <neal@gompa.dev>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> Co-developed-by: Sven Peter <sven@kernel.org>
> Signed-off-by: Sven Peter <sven@kernel.org>
> Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
> ---
>  MAINTAINERS                       |   1 +
>  drivers/input/misc/Kconfig        |  11 ++
>  drivers/input/misc/Makefile       |   1 +
>  drivers/input/misc/macsmc-input.c | 208 +++++++++++++++++++++++++
>  4 files changed, 221 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 79b9f40224a9..e8283f127f11 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2451,6 +2451,7 @@ F:	drivers/hwmon/macsmc-hwmon.c
>  F:	drivers/pmdomain/apple/
>  F:	drivers/i2c/busses/i2c-pasemi-core.c
>  F:	drivers/i2c/busses/i2c-pasemi-platform.c
> +F:	drivers/input/misc/macsmc-input.c
>  F:	drivers/input/touchscreen/apple_z2.c
>  F:	drivers/iommu/apple-dart.c
>  F:	drivers/iommu/io-pgtable-dart.c
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 0e6b49fb54bc..5ab8a4729e0a 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -981,4 +981,15 @@ config INPUT_STPMIC1_ONKEY
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called stpmic1_onkey.
>  
> +config INPUT_MACSMC_INPUT

INPUT_MACSMC_INPUT looks redundant, is there a reason for not just using
INPUT_MACSMC?

> +	tristate "Apple Mac SMC lid/buttons"
> +	depends on MFD_MACSMC
> +	help
> +	  Say Y here if you want to use the input events delivered via the
> +	  SMC controller on Apple Mac machines using the macsmc driver.
> +	  This includes lid open/close and the power button.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called macsmc-input.
> +
>  endif
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index ae857c24f48e..480a0d08d4ae 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_INPUT_IQS7222)		+= iqs7222.o
>  obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
>  obj-$(CONFIG_INPUT_KXTJ9)		+= kxtj9.o
>  obj-$(CONFIG_INPUT_M68K_BEEP)		+= m68kspkr.o
> +obj-$(CONFIG_INPUT_MACSMC_INPUT)	+= macsmc-input.o
>  obj-$(CONFIG_INPUT_MAX7360_ROTARY)	+= max7360-rotary.o
>  obj-$(CONFIG_INPUT_MAX77650_ONKEY)	+= max77650-onkey.o
>  obj-$(CONFIG_INPUT_MAX77693_HAPTIC)	+= max77693-haptic.o
> diff --git a/drivers/input/misc/macsmc-input.c b/drivers/input/misc/macsmc-input.c
> new file mode 100644
> index 000000000000..ebbc7dfc31f5
> --- /dev/null
> +++ b/drivers/input/misc/macsmc-input.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC input event driver
> + * Copyright The Asahi Linux Contributors
> + *
> + * This driver exposes HID events from the SMC as an input device.

s/HID //

> + * This includes the lid open/close and power button notifications.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/input.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/macsmc.h>
> +#include <linux/module.h>
> +#include <linux/reboot.h>
> +
> +/**
> + * struct macsmc_input
> + * @dev: Underlying struct device for the input sub-device
> + * @smc: Pointer to apple_smc struct of the mfd parent
> + * @input: Allocated input_dev; devres managed
> + * @nb: Notifier block used for incoming events from SMC (e.g. button pressed down)
> + * @wakeup_mode: Set to true when system is suspended and power button events should wake it
> + */
> +struct macsmc_input {
> +	struct device *dev;
> +	struct apple_smc *smc;
> +	struct input_dev *input;
> +	struct notifier_block nb;
> +	bool wakeup_mode;
> +};
> +
> +#define SMC_EV_BTN 0x7201
> +#define SMC_EV_LID 0x7203
> +
> +#define BTN_POWER		0x01 /* power button on e.g. Mac Mini chasis pressed */
> +#define BTN_TOUCHID		0x06 /* combined TouchID / power button on MacBooks pressed */
> +#define BTN_POWER_HELD_SHORT	0xfe /* power button briefly held down */
> +#define BTN_POWER_HELD_LONG	0x00 /* power button held down; sent just before forced poweroff */
> +
> +static void macsmc_input_event_button(struct macsmc_input *smcin, unsigned long event)
> +{
> +	u8 button = (event >> 8) & 0xff;
> +	u8 state = !!(event & 0xff);
> +
> +	switch (button) {
> +	case BTN_POWER:
> +	case BTN_TOUCHID:
> +		if (smcin->wakeup_mode) {
> +			if (state)
> +				pm_wakeup_event(smcin->dev, 0);
> +		} else {
> +			input_report_key(smcin->input, KEY_POWER, state);
> +			input_sync(smcin->input);
> +		}
> +		break;
> +	case BTN_POWER_HELD_SHORT: /* power button held down; ignore */
> +		break;
> +	case BTN_POWER_HELD_LONG:
> +		/*
> +		 * If we get here the power button has been held down for a while and
> +		 * we have about 4 seconds before forced power-off is triggered by SMC.
> +		 * Try to do an emergency shutdown to make sure the NVMe cache is
> +		 * flushed. macOS actually does this by panicing (!)...
> +		 */
> +		if (state) {
> +			dev_crit(smcin->dev, "Triggering forced shutdown!\n");
> +			if (kernel_can_power_off())
> +				kernel_power_off();
> +			else /* Missing macsmc-reboot driver? */
> +				kernel_restart("SMC power button triggered restart");
> +		}
> +		break;
> +	default:
> +		dev_warn(smcin->dev, "Unknown SMC button event: %04lx\n", event & 0xffff);
> +	}
> +}
> +
> +static void macsmc_input_event_lid(struct macsmc_input *smcin, unsigned long event)
> +{
> +	u8 lid_state = !!((event >> 8) & 0xff);
> +
> +	if (smcin->wakeup_mode && !lid_state)
> +		pm_wakeup_event(smcin->dev, 0);
> +
> +	input_report_switch(smcin->input, SW_LID, lid_state);
> +	input_sync(smcin->input);
> +}
> +
> +static int macsmc_input_event(struct notifier_block *nb, unsigned long event, void *data)
> +{
> +	struct macsmc_input *smcin = container_of(nb, struct macsmc_input, nb);
> +	u16 type = event >> 16;
> +
> +	switch (type) {
> +	case SMC_EV_BTN:
> +		macsmc_input_event_button(smcin, event);
> +		return NOTIFY_OK;
> +	case SMC_EV_LID:
> +		macsmc_input_event_lid(smcin, event);
> +		return NOTIFY_OK;
> +	default:
> +		/* SMC event meant for another driver */
> +		return NOTIFY_DONE;
> +	}
> +}
> +
> +static int macsmc_input_probe(struct platform_device *pdev)
> +{
> +	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> +	struct macsmc_input *smcin;
> +	bool have_lid, have_power;
> +	int error;
> +
> +	/* Bail early if this SMC neither supports power button nor lid events */
> +	have_lid = apple_smc_key_exists(smc, SMC_KEY(MSLD));
> +	have_power = apple_smc_key_exists(smc, SMC_KEY(bHLD));
> +	if (!have_lid && !have_power)
> +		return -ENODEV;
> +
> +	smcin = devm_kzalloc(&pdev->dev, sizeof(*smcin), GFP_KERNEL);
> +	if (!smcin)
> +		return -ENOMEM;
> +
> +	smcin->dev = &pdev->dev;
> +	smcin->smc = smc;
> +	platform_set_drvdata(pdev, smcin);
> +
> +	smcin->input = devm_input_allocate_device(&pdev->dev);
> +	if (!smcin->input)
> +		return -ENOMEM;
> +
> +	smcin->input->phys = "macsmc-input (0)";
> +	smcin->input->name = "Apple SMC power/lid events";
> +
> +	if (have_lid)
> +		input_set_capability(smcin->input, EV_SW, SW_LID);
> +	if (have_power)
> +		input_set_capability(smcin->input, EV_KEY, KEY_POWER);
> +
> +	if (have_lid) {
> +		u8 val;
> +
> +		error = apple_smc_read_u8(smc, SMC_KEY(MSLD), &val);
> +		if (error < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial lid state\n");
> +		else
> +			input_report_switch(smcin->input, SW_LID, val);
> +	}
> +
> +	if (have_power) {
> +		u32 val;
> +
> +		error = apple_smc_read_u32(smc, SMC_KEY(bHLD), &val);
> +		if (error < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial power button state\n");
> +		else
> +			input_report_key(smcin->input, KEY_POWER, val & 1);
> +	}
> +
> +	error = input_register_device(smcin->input);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to register input device: %d\n", error);
> +		return error;
> +	}
> +
> +	input_sync(smcin->input);
> +
> +	smcin->nb.notifier_call = macsmc_input_event;
> +	blocking_notifier_chain_register(&smc->event_handlers, &smcin->nb);
> +
> +	device_init_wakeup(&pdev->dev, 1);
> +
> +	return 0;
> +}
> +
> +static int macsmc_input_pm_prepare(struct device *dev)
> +{
> +	struct macsmc_input *smcin = dev_get_drvdata(dev);
> +
> +	smcin->wakeup_mode = true;
> +	return 0;
> +}
> +
> +static void macsmc_input_pm_complete(struct device *dev)
> +{
> +	struct macsmc_input *smcin = dev_get_drvdata(dev);
> +
> +	smcin->wakeup_mode = false;
> +}
> +
> +static const struct dev_pm_ops macsmc_input_pm_ops = {
> +	.prepare = macsmc_input_pm_prepare,
> +	.complete = macsmc_input_pm_complete,
> +};
> +
> +static struct platform_driver macsmc_input_driver = {
> +	.driver = {
> +		.name = "macsmc-input",
> +		.pm = &macsmc_input_pm_ops,
> +	},
> +	.probe = macsmc_input_probe,
> +};
> +module_platform_driver(macsmc_input_driver);
> +
> +MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_DESCRIPTION("Apple SMC input driver");

mssing 'MODULE_ALIAS("platform:macsmc-input");'. This is required when
using MFD_CELL_NAME(). My ask for it to be removed was based on my
mistaken idea to add a pointless node to the DT and use MFD_CELL_OF().

Janne