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Date: Fri, 22 Mar 2024 19:48:57 +0100
From: Armin Wolf <W_Armin@....de>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Ai Chao <aichao@...inos.cn>, Hans de Goede <hdegoede@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v11] platform/x86: add lenovo wmi camera button driver
Am 22.03.24 um 17:47 schrieb 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@...inos.cn>
>>>> ---
>>>> 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@...inos.cn>
>>>> + * 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.
Hi,
AFAIK calling mutex_destroy() allows the lock debugging code to catch
attempts to access the mutex afterwards, so this would allow us to spot
such issues when enabling lock debugging.
For the whole driver:
Reviewed-by: Armin Wolf <W_Armin@....de>
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