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

[Kuppuswamy Sathyanarayanan]

On 3/22/24 7:39 AM, Ilpo Järvinen wrote:
> On Fri, 22 Mar 2024, Kuppuswamy Sathyanarayanan wrote:
>> 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.
> Is all debug code going to be happy if it's not called?
>
I am not aware of any issue. Do you have any details about it?

>From the comments, it looks like mutex_destroy() is used to mark a
mutex unusable. Not sure why we need to mark a device priv lock
unusable during the unload process.


-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer