Re: [PATCH v11] platform/x86: add lenovo wmi camera button driver

[Kuppuswamy Sathyanarayanan]

On 3/21/24 11:47 PM, Ai Chao wrote:
> Add lenovo generic wmi driver to support camera button.
> The Camera button is a GPIO device. This driver receives ACPI notifyi
> when the camera button is switched on/off. This driver is used in
> Lenovo A70, it is a Computer integrated machine.
>
> Signed-off-by: Ai Chao <aichao@xxxxxxxxxx>
> ---
> v11: remove input_unregister_device.
> v10: Add lenovo_wmi_remove and mutex_destroy.
> v9: Add mutex for wmi notify.
> v8: Dev_deb convert to dev_err.
> v7: Add dev_dbg and remove unused dev in struct.
> v6: Modify SW_CAMERA_LENS_COVER to KEY_CAMERA_ACCESS_ENABLE/KEY_CAMERA_ACCESS_DISABLE.
> v5: Remove camera button groups, modify KEY_CAMERA to SW_CAMERA_LENS_COVER.
> v4: Remove lenovo_wmi_input_setup, move camera_mode into struct lenovo_wmi_priv.
> v3: Remove lenovo_wmi_remove function.
> v2: Adjust GPL v2 to GPL, adjust sprintf to sysfs_emit.
>
>  drivers/platform/x86/Kconfig             |  12 +++
>  drivers/platform/x86/Makefile            |   1 +
>  drivers/platform/x86/lenovo-wmi-camera.c | 126 +++++++++++++++++++++++
>  3 files changed, 139 insertions(+)
>  create mode 100644 drivers/platform/x86/lenovo-wmi-camera.c
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index bdd302274b9a..9506a455b547 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1001,6 +1001,18 @@ config INSPUR_PLATFORM_PROFILE
>  	To compile this driver as a module, choose M here: the module
>  	will be called inspur-platform-profile.
>  
> +config LENOVO_WMI_CAMERA
> +	tristate "Lenovo WMI Camera Button driver"
> +	depends on ACPI_WMI
> +	depends on INPUT
> +	help
> +	  This driver provides support for Lenovo camera button. The Camera
> +	  button is a GPIO device. This driver receives ACPI notify when the
> +	  camera button is switched on/off.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called lenovo-wmi-camera.
> +
>  source "drivers/platform/x86/x86-android-tablets/Kconfig"
>  
>  config FW_ATTR_CLASS
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 1de432e8861e..217e94d7c877 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -66,6 +66,7 @@ obj-$(CONFIG_SENSORS_HDAPS)	+= hdaps.o
>  obj-$(CONFIG_THINKPAD_ACPI)	+= thinkpad_acpi.o
>  obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
>  obj-$(CONFIG_YOGABOOK)		+= lenovo-yogabook.o
> +obj-$(CONFIG_LENOVO_WMI_CAMERA)	+= lenovo-wmi-camera.o
>  
>  # Intel
>  obj-y				+= intel/
> diff --git a/drivers/platform/x86/lenovo-wmi-camera.c b/drivers/platform/x86/lenovo-wmi-camera.c
> new file mode 100644
> index 000000000000..fda936e2f37c
> --- /dev/null
> +++ b/drivers/platform/x86/lenovo-wmi-camera.c
> @@ -0,0 +1,126 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Lenovo WMI Camera Button Driver
> + *
> + * Author: Ai Chao <aichao@xxxxxxxxxx>
> + * Copyright (C) 2024 KylinSoft Corporation.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/input.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/wmi.h>
> +
> +#define WMI_LENOVO_CAMERABUTTON_EVENT_GUID "50C76F1F-D8E4-D895-0A3D-62F4EA400013"
> +
> +struct lenovo_wmi_priv {
> +	struct input_dev *idev;
> +	struct mutex notify_lock;	/* lenovo wmi camera button notify lock */
> +};
> +
> +enum {
> +	SW_CAMERA_OFF	= 0,
> +	SW_CAMERA_ON	= 1,
> +};
> +
> +static void lenovo_wmi_notify(struct wmi_device *wdev, union acpi_object *obj)
> +{
> +	struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
> +	unsigned int keycode;
> +	u8 camera_mode;
> +
> +	if (obj->type != ACPI_TYPE_BUFFER) {
> +		dev_err(&wdev->dev, "Bad response type %u\n", obj->type);
> +		return;
> +	}
> +
> +	if (obj->buffer.length != 1) {
> +		dev_err(&wdev->dev, "Invalid buffer length %u\n", obj->buffer.length);
> +		return;
> +	}
> +
> +	/* obj->buffer.pointer[0] is camera mode:
> +	 *      0 camera close
> +	 *      1 camera open
> +	 */
> +	camera_mode = obj->buffer.pointer[0];
> +	if (camera_mode > SW_CAMERA_ON) {
> +		dev_err(&wdev->dev, "Unknown camera mode %u\n", camera_mode);
> +		return;
> +	}
> +
> +	mutex_lock(&priv->notify_lock);
> +
> +	keycode = (camera_mode == SW_CAMERA_ON ?
> +		   KEY_CAMERA_ACCESS_ENABLE : KEY_CAMERA_ACCESS_DISABLE);
> +	input_report_key(priv->idev, keycode, 1);
> +	input_sync(priv->idev);
> +	input_report_key(priv->idev, keycode, 0);
> +	input_sync(priv->idev);
> +
> +	mutex_unlock(&priv->notify_lock);
> +}
> +
> +static int lenovo_wmi_probe(struct wmi_device *wdev, const void *context)
> +{
> +	struct lenovo_wmi_priv *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	dev_set_drvdata(&wdev->dev, priv);
> +
> +	priv->idev = devm_input_allocate_device(&wdev->dev);
> +	if (!priv->idev)
> +		return -ENOMEM;
> +
> +	priv->idev->name = "Lenovo WMI Camera Button";
> +	priv->idev->phys = "wmi/input0";
> +	priv->idev->id.bustype = BUS_HOST;
> +	priv->idev->dev.parent = &wdev->dev;
> +	input_set_capability(priv->idev, EV_KEY, KEY_CAMERA_ACCESS_ENABLE);
> +	input_set_capability(priv->idev, EV_KEY, KEY_CAMERA_ACCESS_DISABLE);
> +
> +	ret = input_register_device(priv->idev);
> +	if (ret)
> +		return ret;
> +
> +	mutex_init(&priv->notify_lock);
> +
> +	return 0;
> +}
> +
> +static void lenovo_wmi_remove(struct wmi_device *wdev)
> +{
> +	struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
> +
> +	mutex_destroy(&priv->notify_lock);

Do you really need to call mutex_destroy() during the module unload?

I don't think kernel allocates any memory during mutex_init() that needs
be freed.

> +}
> +
> +static const struct wmi_device_id lenovo_wmi_id_table[] = {
> +	{ .guid_string = WMI_LENOVO_CAMERABUTTON_EVENT_GUID },
> +	{  }
> +};
> +
> +static struct wmi_driver lenovo_wmi_driver = {
> +	.driver = {
> +		.name = "lenovo-wmi-camera",
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +	.id_table = lenovo_wmi_id_table,
> +	.no_singleton = true,
> +	.probe = lenovo_wmi_probe,
> +	.notify = lenovo_wmi_notify,
> +	.remove = lenovo_wmi_remove,
> +};
> +
> +module_wmi_driver(lenovo_wmi_driver);
> +
> +MODULE_DEVICE_TABLE(wmi, lenovo_wmi_id_table);
> +MODULE_AUTHOR("Ai Chao <aichao@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Lenovo WMI Camera Button Driver");
> +MODULE_LICENSE("GPL");

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer