Re: [PATCH v8] platform/x86: add lenovo wmi camera button driver

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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@kylinos.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@kylinos.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?

-- 
 i.

> > +
> > +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_KEY, KEY_CAMERA_ACCESS_ENABLE);
> > +	input_set_capability(priv->idev, EV_KEY, KEY_CAMERA_ACCESS_DISABLE);
> > +
> > +	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@kylinos.cn>");
> > +MODULE_DESCRIPTION("Lenovo WMI Camera Button Driver");
> > +MODULE_LICENSE("GPL");
> 
> Looks good to me.
> 
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
>