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Message-ID: <4138a86e-c0cd-4bd1-948c-88dd73749027@gmx.de>
Date: Thu, 7 Mar 2024 19:17:04 +0100
From: Armin Wolf <W_Armin@....de>
To: Ai Chao <aichao@...inos.cn>, hdegoede@...hat.com,
ilpo.jarvinen@...ux.intel.com, linux-kernel@...r.kernel.org,
platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v5] platform/x86: add lenovo wmi camera button driver
Am 07.03.24 um 09:59 schrieb Ai Chao:
> 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>
> ---
> 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 | 89 ++++++++++++++++++++++++
> 3 files changed, 102 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..571d67ade8ac
> --- /dev/null
> +++ b/drivers/platform/x86/lenovo-wmi-camera.c
> @@ -0,0 +1,89 @@
> +// 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/wmi.h>
> +
> +#define WMI_LENOVO_CAMERABUTTON_EVENT_GUID "50C76F1F-D8E4-D895-0A3D-62F4EA400013"
> +
> +struct lenovo_wmi_priv {
> + struct input_dev *idev;
> + struct device *dev;
> +};
> +
> +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);
> +
> + if (obj->type == ACPI_TYPE_BUFFER &&
> + obj->buffer.pointer[0] <= SW_CAMERA_ON) {
Hi,
please check that the ACPI buffer has an appropriate size before you access it.
In this case, check that the ACPI buffer has a length of 1;
> + /* obj->buffer.pointer[0] is camera mode:
> + * 0 camera close
> + * 1 camera open
> + */
> + input_report_switch(priv->idev, SW_CAMERA_LENS_COVER,
> + obj->buffer.pointer[0]);
If SW_CAMERA_LENS_COVER is set, then it means that the camera lens is covered. So in this case
you have to pass 1 when the camera is closed and 0 when the camera is open (basically the opposite
of camera mode).
> + input_sync(priv->idev);
> + } else {
> + dev_dbg(&wdev->dev, "Bad response type %d\n", obj->type);
> + }
> +}
> +
> +static int lenovo_wmi_probe(struct wmi_device *wdev, const void *context)
> +{
> + struct lenovo_wmi_priv *priv;
> +
> + 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_SW, SW_CAMERA_LENS_COVER);
> +
Is there a way to determine the current state of the camera switch without having
to wait for an WMI event?
If its not possible to determine the current state of the camera switch, then your
driver has to defer the initialization of the input device until it knows the current
state of the camera switch. Otherwise the initial switch state reported by the
input device might be wrong.
In this case, that means your driver must initialize the input device when receiving
a valid WMI event for the first time.
Basically when your driver receives a WMI event, it has to check if the input device
is already initialized. If this is not the case, then the input device is initialized.
Please protect this check and the input device initialization with a mutex, since WMI
event handling is multithreaded.
After that the event is reported as usual.
Other than that, the driver seems to be in good shape.
Thanks,
Armin Wolf
> + return input_register_device(priv->idev);
> +}
> +
> +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,
> +};
> +
> +module_wmi_driver(lenovo_wmi_driver);
> +
> +MODULE_DEVICE_TABLE(wmi, lenovo_wmi_id_table);
> +MODULE_AUTHOR("Ai Chao <aichao@...inos.cn>");
> +MODULE_DESCRIPTION("Lenovo WMI Camera Button Driver");
> +MODULE_LICENSE("GPL");
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