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Date: Fri, 15 Mar 2024 18:26:23 +0100
From: Armin Wolf <W_Armin@....de>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Ai Chao <aichao@...inos.cn>
Cc: Hans de Goede <hdegoede@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v8] platform/x86: add lenovo wmi camera button driver
Am 15.03.24 um 12:51 schrieb Ilpo Järvinen:
> On Thu, 14 Mar 2024, Armin Wolf wrote:
>
>> Am 14.03.24 um 06:03 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>
>>> ---
>>> 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 | 108 +++++++++++++++++++++++
>>> 3 files changed, 121 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..f83e3ccd9189
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/lenovo-wmi-camera.c
>>> @@ -0,0 +1,108 @@
>>> +// 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;
>>> +};
>>> +
>>> +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);
>>> + 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;
>>> + }
>>> +
>>> + if (camera_mode == SW_CAMERA_ON) {
>>> + input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 1);
>>> + input_sync(priv->idev);
>>> + input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 0);
>>> + } else {
>>> + input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 1);
>>> + input_sync(priv->idev);
>>> + input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 0);
>>> + }
> While not exactly wrong the if seems unnecessary, you could do:
>
> unsigned int keycode;
>
> ...
>
> 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);
>>> +}
> Armin,
>
> I tried to figure out the concurrency rules for the WMI notify handler but
> came up basically nothing. I suppose it boils down on ACPI notify handling
> and I couldn't find useful documentation about that either. :-/
>
> Could you perhaps add this information into WMI documentation?
As far as i know, the ACPI notify handlers can be scheduled concurrently on all CPUs,
see https://lore.kernel.org/all/7617703.EvYhyI6sBW@kreacher/ for details.
I will add a short note about this to the WMI driver guide which i plan to upstream
soon (after the EC handler stuff is finished).
Thanks,
Armin Wolf
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