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.

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-hid.c | 209 +++++++++++++++++++++++++
 4 files changed, 222 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 2eb23522654dd050262eb06e077587030cc335aa..b3b5220fcd0d4bbef67613c8ee9afa880c0aa45d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2412,6 +2412,7 @@ 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-hid.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 0fb21c99a5e3d1230d7f40f99e0c2d360bbe80e8..a430c50e7f63f245bba56bd526026ec7901cf821 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -961,4 +961,15 @@ config INPUT_STPMIC1_ONKEY
 	  To compile this driver as a module, choose M here: the
 	  module will be called stpmic1_onkey.
 
+config INPUT_MACSMC_HID
+	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-hid.
+
 endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index d468c8140b93da5bb537e8a3baea2b90e7bb4229..95b8ebbb9ebbe6f3afc9db724d2ebeba1d75d1a6 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-$(CONFIG_INPUT_MACSMC_HID)		+= macsmc-hid.o
 obj-$(CONFIG_INPUT_MAX77650_ONKEY)	+= max77650-onkey.o
 obj-$(CONFIG_INPUT_MAX77693_HAPTIC)	+= max77693-haptic.o
 obj-$(CONFIG_INPUT_MAX8925_ONKEY)	+= max8925_onkey.o
diff --git a/drivers/input/misc/macsmc-hid.c b/drivers/input/misc/macsmc-hid.c
new file mode 100644
index 0000000000000000000000000000000000000000..c7cd56e5c17f08936cc623f7d3690f27e05012a5
--- /dev/null
+++ b/drivers/input/misc/macsmc-hid.c
@@ -0,0 +1,209 @@
+// 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.
+ * 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_hid
+ * @dev: Underlying struct device for the HID 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_hid {
+	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_hid_event_button(struct macsmc_hid *smchid, unsigned long event)
+{
+	u8 button = (event >> 8) & 0xff;
+	u8 state = !!(event & 0xff);
+
+	switch (button) {
+	case BTN_POWER:
+	case BTN_TOUCHID:
+		if (smchid->wakeup_mode) {
+			if (state)
+				pm_wakeup_hard_event(smchid->dev);
+		} else {
+			input_report_key(smchid->input, KEY_POWER, state);
+			input_sync(smchid->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(smchid->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(smchid->dev, "Unknown SMC button event: %04lx\n", event & 0xffff);
+	}
+}
+
+static void macsmc_hid_event_lid(struct macsmc_hid *smchid, unsigned long event)
+{
+	u8 lid_state = !!((event >> 8) & 0xff);
+
+	if (smchid->wakeup_mode && !lid_state)
+		pm_wakeup_hard_event(smchid->dev);
+
+	input_report_switch(smchid->input, SW_LID, lid_state);
+	input_sync(smchid->input);
+}
+
+static int macsmc_hid_event(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct macsmc_hid *smchid = container_of(nb, struct macsmc_hid, nb);
+	u16 type = event >> 16;
+
+	switch (type) {
+	case SMC_EV_BTN:
+		macsmc_hid_event_button(smchid, event);
+		return NOTIFY_OK;
+	case SMC_EV_LID:
+		macsmc_hid_event_lid(smchid, event);
+		return NOTIFY_OK;
+	default:
+		/* SMC event meant for another driver */
+		return NOTIFY_DONE;
+	}
+}
+
+static int macsmc_hid_probe(struct platform_device *pdev)
+{
+	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
+	struct macsmc_hid *smchid;
+	bool have_lid, have_power;
+	int ret;
+
+	/* 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;
+
+	smchid = devm_kzalloc(&pdev->dev, sizeof(*smchid), GFP_KERNEL);
+	if (!smchid)
+		return -ENOMEM;
+
+	smchid->dev = &pdev->dev;
+	smchid->smc = smc;
+	platform_set_drvdata(pdev, smchid);
+
+	smchid->input = devm_input_allocate_device(&pdev->dev);
+	if (!smchid->input)
+		return -ENOMEM;
+
+	smchid->input->phys = "macsmc-hid (0)";
+	smchid->input->name = "Apple SMC power/lid events";
+
+	if (have_lid)
+		input_set_capability(smchid->input, EV_SW, SW_LID);
+	if (have_power)
+		input_set_capability(smchid->input, EV_KEY, KEY_POWER);
+
+	ret = input_register_device(smchid->input);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register input device: %d\n", ret);
+		return ret;
+	}
+
+	if (have_lid) {
+		u8 val;
+
+		ret = apple_smc_read_u8(smc, SMC_KEY(MSLD), &val);
+		if (ret < 0)
+			dev_warn(&pdev->dev, "Failed to read initial lid state\n");
+		else
+			input_report_switch(smchid->input, SW_LID, val);
+	}
+
+	if (have_power) {
+		u32 val;
+
+		ret = apple_smc_read_u32(smc, SMC_KEY(bHLD), &val);
+		if (ret < 0)
+			dev_warn(&pdev->dev, "Failed to read initial power button state\n");
+		else
+			input_report_key(smchid->input, KEY_POWER, val & 1);
+	}
+
+	input_sync(smchid->input);
+
+	smchid->nb.notifier_call = macsmc_hid_event;
+	blocking_notifier_chain_register(&smc->event_handlers, &smchid->nb);
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	return 0;
+}
+
+static int macsmc_hid_pm_prepare(struct device *dev)
+{
+	struct macsmc_hid *smchid = dev_get_drvdata(dev);
+
+	smchid->wakeup_mode = true;
+	return 0;
+}
+
+static void macsmc_hid_pm_complete(struct device *dev)
+{
+	struct macsmc_hid *smchid = dev_get_drvdata(dev);
+
+	smchid->wakeup_mode = false;
+}
+
+static const struct dev_pm_ops macsmc_hid_pm_ops = {
+	.prepare = macsmc_hid_pm_prepare,
+	.complete = macsmc_hid_pm_complete,
+};
+
+static struct platform_driver macsmc_hid_driver = {
+	.driver = {
+		.name = "macsmc-hid",
+		.pm = &macsmc_hid_pm_ops,
+	},
+	.probe = macsmc_hid_probe,
+};
+module_platform_driver(macsmc_hid_driver);
+
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC HID driver");
+MODULE_ALIAS("platform:macsmc-hid");

-- 
2.51.0

On Wed, Aug 27, 2025 at 09:22:41PM +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.
> 
> 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-hid.c | 209 +++++++++++++++++++++++++

I would rename this driver to macsmc-input. I would expect hid driver to
live in drivers/hid/ and use HID report descriptors

>  4 files changed, 222 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2eb23522654dd050262eb06e077587030cc335aa..b3b5220fcd0d4bbef67613c8ee9afa880c0aa45d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2412,6 +2412,7 @@ 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-hid.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 0fb21c99a5e3d1230d7f40f99e0c2d360bbe80e8..a430c50e7f63f245bba56bd526026ec7901cf821 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -961,4 +961,15 @@ config INPUT_STPMIC1_ONKEY
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called stpmic1_onkey.
>  
> +config INPUT_MACSMC_HID
> +	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-hid.
> +
>  endif
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index d468c8140b93da5bb537e8a3baea2b90e7bb4229..95b8ebbb9ebbe6f3afc9db724d2ebeba1d75d1a6 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-$(CONFIG_INPUT_MACSMC_HID)		+= macsmc-hid.o
>  obj-$(CONFIG_INPUT_MAX77650_ONKEY)	+= max77650-onkey.o
>  obj-$(CONFIG_INPUT_MAX77693_HAPTIC)	+= max77693-haptic.o
>  obj-$(CONFIG_INPUT_MAX8925_ONKEY)	+= max8925_onkey.o
> diff --git a/drivers/input/misc/macsmc-hid.c b/drivers/input/misc/macsmc-hid.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..c7cd56e5c17f08936cc623f7d3690f27e05012a5
> --- /dev/null
> +++ b/drivers/input/misc/macsmc-hid.c
> @@ -0,0 +1,209 @@
> +// 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.
> + * 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_hid
> + * @dev: Underlying struct device for the HID 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_hid {
> +	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_hid_event_button(struct macsmc_hid *smchid, unsigned long event)
> +{
> +	u8 button = (event >> 8) & 0xff;
> +	u8 state = !!(event & 0xff);
> +
> +	switch (button) {
> +	case BTN_POWER:
> +	case BTN_TOUCHID:
> +		if (smchid->wakeup_mode) {
> +			if (state)
> +				pm_wakeup_hard_event(smchid->dev);
> +		} else {
> +			input_report_key(smchid->input, KEY_POWER, state);
> +			input_sync(smchid->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(smchid->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(smchid->dev, "Unknown SMC button event: %04lx\n", event & 0xffff);
> +	}
> +}
> +
> +static void macsmc_hid_event_lid(struct macsmc_hid *smchid, unsigned long event)
> +{
> +	u8 lid_state = !!((event >> 8) & 0xff);
> +
> +	if (smchid->wakeup_mode && !lid_state)
> +		pm_wakeup_hard_event(smchid->dev);
> +
> +	input_report_switch(smchid->input, SW_LID, lid_state);
> +	input_sync(smchid->input);
> +}
> +
> +static int macsmc_hid_event(struct notifier_block *nb, unsigned long event, void *data)
> +{
> +	struct macsmc_hid *smchid = container_of(nb, struct macsmc_hid, nb);
> +	u16 type = event >> 16;
> +
> +	switch (type) {
> +	case SMC_EV_BTN:
> +		macsmc_hid_event_button(smchid, event);
> +		return NOTIFY_OK;
> +	case SMC_EV_LID:
> +		macsmc_hid_event_lid(smchid, event);
> +		return NOTIFY_OK;
> +	default:
> +		/* SMC event meant for another driver */
> +		return NOTIFY_DONE;
> +	}
> +}
> +
> +static int macsmc_hid_probe(struct platform_device *pdev)
> +{
> +	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> +	struct macsmc_hid *smchid;
> +	bool have_lid, have_power;
> +	int ret;
> +
> +	/* 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;
> +
> +	smchid = devm_kzalloc(&pdev->dev, sizeof(*smchid), GFP_KERNEL);
> +	if (!smchid)
> +		return -ENOMEM;
> +
> +	smchid->dev = &pdev->dev;
> +	smchid->smc = smc;
> +	platform_set_drvdata(pdev, smchid);
> +
> +	smchid->input = devm_input_allocate_device(&pdev->dev);
> +	if (!smchid->input)
> +		return -ENOMEM;
> +
> +	smchid->input->phys = "macsmc-hid (0)";
> +	smchid->input->name = "Apple SMC power/lid events";
> +
> +	if (have_lid)
> +		input_set_capability(smchid->input, EV_SW, SW_LID);
> +	if (have_power)
> +		input_set_capability(smchid->input, EV_KEY, KEY_POWER);
> +
> +	ret = input_register_device(smchid->input);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register input device: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (have_lid) {
> +		u8 val;
> +
> +		ret = apple_smc_read_u8(smc, SMC_KEY(MSLD), &val);
> +		if (ret < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial lid state\n");
> +		else
> +			input_report_switch(smchid->input, SW_LID, val);
> +	}
> +
> +	if (have_power) {
> +		u32 val;
> +
> +		ret = apple_smc_read_u32(smc, SMC_KEY(bHLD), &val);
> +		if (ret < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial power button state\n");
> +		else
> +			input_report_key(smchid->input, KEY_POWER, val & 1);
> +	}
> +
> +	input_sync(smchid->input);
> +
> +	smchid->nb.notifier_call = macsmc_hid_event;
> +	blocking_notifier_chain_register(&smc->event_handlers, &smchid->nb);
> +
> +	device_init_wakeup(&pdev->dev, 1);
> +
> +	return 0;
> +}
> +
> +static int macsmc_hid_pm_prepare(struct device *dev)
> +{
> +	struct macsmc_hid *smchid = dev_get_drvdata(dev);
> +
> +	smchid->wakeup_mode = true;
> +	return 0;
> +}
> +
> +static void macsmc_hid_pm_complete(struct device *dev)
> +{
> +	struct macsmc_hid *smchid = dev_get_drvdata(dev);
> +
> +	smchid->wakeup_mode = false;
> +}
> +
> +static const struct dev_pm_ops macsmc_hid_pm_ops = {
> +	.prepare = macsmc_hid_pm_prepare,
> +	.complete = macsmc_hid_pm_complete,
> +};
> +
> +static struct platform_driver macsmc_hid_driver = {
> +	.driver = {
> +		.name = "macsmc-hid",
> +		.pm = &macsmc_hid_pm_ops,
> +	},
> +	.probe = macsmc_hid_probe,
> +};
> +module_platform_driver(macsmc_hid_driver);
> +
> +MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_DESCRIPTION("Apple SMC HID driver");
> +MODULE_ALIAS("platform:macsmc-hid");

The module alias should be removed.

Janne

Hi James,

On Wed, Aug 27, 2025 at 09:22:41PM +1000, James Calligeros wrote:
> +static void macsmc_hid_event_button(struct macsmc_hid *smchid, unsigned long event)
> +{
> +	u8 button = (event >> 8) & 0xff;
> +	u8 state = !!(event & 0xff);
> +
> +	switch (button) {
> +	case BTN_POWER:
> +	case BTN_TOUCHID:
> +		if (smchid->wakeup_mode) {
> +			if (state)
> +				pm_wakeup_hard_event(smchid->dev);
> +		} else {
> +			input_report_key(smchid->input, KEY_POWER, state);
> +			input_sync(smchid->input);
> +		}

I believe you should be using pm_wakeup_event() in all cases so that
pressing power would interrupt suspend even if resume() handler has not
been run yet. Also I do not think suppressing KEY_POWER is needed.
Userspace should be smart and decide whether to shutdown the system or
not when receiving KEY_POWER depending on the overall system state.

...
> +
> +static int macsmc_hid_probe(struct platform_device *pdev)
> +{
> +	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> +	struct macsmc_hid *smchid;
> +	bool have_lid, have_power;
> +	int ret;

	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;
> +
> +	smchid = devm_kzalloc(&pdev->dev, sizeof(*smchid), GFP_KERNEL);
> +	if (!smchid)
> +		return -ENOMEM;
> +
> +	smchid->dev = &pdev->dev;
> +	smchid->smc = smc;
> +	platform_set_drvdata(pdev, smchid);
> +
> +	smchid->input = devm_input_allocate_device(&pdev->dev);
> +	if (!smchid->input)
> +		return -ENOMEM;
> +
> +	smchid->input->phys = "macsmc-hid (0)";
> +	smchid->input->name = "Apple SMC power/lid events";
> +
> +	if (have_lid)
> +		input_set_capability(smchid->input, EV_SW, SW_LID);
> +	if (have_power)
> +		input_set_capability(smchid->input, EV_KEY, KEY_POWER);
> +
> +	ret = input_register_device(smchid->input);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register input device: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (have_lid) {
> +		u8 val;
> +
> +		ret = apple_smc_read_u8(smc, SMC_KEY(MSLD), &val);
> +		if (ret < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial lid state\n");
> +		else
> +			input_report_switch(smchid->input, SW_LID, val);
> +	}
> +
> +	if (have_power) {
> +		u32 val;
> +
> +		ret = apple_smc_read_u32(smc, SMC_KEY(bHLD), &val);
> +		if (ret < 0)
> +			dev_warn(&pdev->dev, "Failed to read initial power button state\n");
> +		else
> +			input_report_key(smchid->input, KEY_POWER, val & 1);
> +	}

Since you are doing this to seed initial switch/button state I would do
this before registering input device (this is safe to do so).

Thanks.

-- 
Dmitry