Re: [PATCH v8 1/2] platform/x86: dell-privacy: Add support for Dell hardware privacy

[Hans de Goede <hdegoede@redhat.com>]

Hi Perry,

On 5/20/21 2:16 PM, Hans de Goede wrote:
> Hi Perry,
> 
> On 5/18/21 3:02 PM, Hans de Goede wrote:
>> Hi Perry,
>>
>> On 5/6/21 1:56 PM, Perry Yuan wrote:
>>> From: Perry Yuan <perry_yuan@dell.com>
>>>
>>> add support for Dell privacy driver for the Dell units equipped
>>> hardware privacy design, which protect users privacy of audio and
>>> camera from hardware level. Once the audio or camera privacy mode
>>> activated, any applications will not get any audio or video stream
>>> when user pressed ctrl+F4 hotkey, audio privacy mode will be
>>> enabled, micmute led will be also changed accordingly
>>> The micmute led is fully controlled by hardware & EC(embedded controller)
>>> and camera mute hotkey is Ctrl+F9. Currently design only emits
>>> SW_CAMERA_LENS_COVER event while the camera lens shutter will be
>>> changed by EC & HW(hardware) control
>>>
>>> *The flow is like this:
>>> 1) User presses key. HW does stuff with this key (timeout timer is started)
>>> 2) WMI event is emitted from BIOS to kernel
>>> 3) WMI event is received by dell-privacy
>>> 4) KEY_MICMUTE emitted from dell-privacy
>>> 5) Userland picks up key and modifies kcontrol for SW mute
>>> 6) Codec kernel driver catches and calls ledtrig_audio_set, like this:
>>>    ledtrig_audio_set(LED_AUDIO_MICMUTE, rt715->micmute_led ? LED_ON :LED_OFF);
>>> 7) If "LED" is set to on dell-privacy notifies EC, and timeout is cancelled,
>>>    HW mic mute activated. If EC not notified, HW mic mute will also be
>>>    activated when timeout used up, it is just later than active ack
>>>
>>> Signed-off-by: Perry Yuan <perry_yuan@dell.com>
>>>
>>> ---
>>> v7 -> v8:
>>> * addressed feedback from Hans
>>> * use sysfs_emit_at in the sysfs attributes
>>> * Update Kconfig
>>> * improve led_classdev_unregister logic in dell-laptop 
>>
>> Thank you, this version looks good to me, with the exception of
>> then issue with e.g. dell-wmi being builtin vs dell-privacy being
>> a module which will lead to the kernel not compiling.
>>
>> I've implemented the fix which I described/suggested in the discussion
>> about this in the v7 thread.
>>
>> I've attached 4 patches:
>>
>> [PATCH 1/4] platform/x86: dell-wmi: Rename dell-wmi.c to dell-wmi-base.c
>> -This is a preparation patch for the Makefile + Kconfig changes suggested
>>  in the v7 email thread
>> [PATCH 2/4] platform/x86: dell-privacy: Add support for Dell hardware privacy
>> -This is your v8 patch (without any changes)
>> [PATCH 3/4] FIXUP platform/x86: dell-privacy: Add support for Dell hardware privacy
>> -This implements the discussed Makefile + Kconfig changes, as well as
>>  renaming dell-privacy-wmi.? to dell-wmi-privacy.? to because the privacy
>>  code now is a part of the dell-wmi module
>> [PATCH 4/4] FIXUP platform/x86: dell-privacy: Add support for Dell hardware privacy
>> -Some small changes from reviewing v8
>>
>> I've also pushed these 4 to my review-hans branch. Perry, if you can let me know if
>> the suggested changes in the 2 FIXUP patches are ok with you then I'll squash
>> them into the 2/4 patch (so that only 1/2 and 2/2 remain) and then push this to
>> for-next.
> 
> Perry, can you please let me know if you are ok with the changes from the 2
> FIXME follow up patches which I attached to my previous email and which are
> also in the pdx86/review-hans branch ?
> 
> I would like to ge this merged and I'm waiting for your ack for this.

Ping? Can I get a reaction to this please. If you are busy with some other
things and need some time, that is fine, but please let me know.

Regards,

Hans






>>> v6 -> v7:
>>> * addressed feedback from Hans
>>> * addressed feedback from Pierre
>>> * optimize some debug format with dev_dbg()
>>> v5 -> v6:
>>> * remove platform driver,combined privacy acpi driver into single wmi
>>>   driver file
>>> * optimize sysfs interface with string added to be more clearly reading
>>> * remove unused function and clear header file
>>> v4 -> v5:
>>> * addressed feedback from Randy Dunlap
>>> * addressed feedback from Pierre-Louis Bossart
>>> * rebase to latest 5.12 rc4 upstream kernel
>>> * fix some space alignment problem
>>> v3 -> v4:
>>> * fix format for Kconfig
>>> * add sysfs document
>>> * add flow comments to the privacy wmi/acpi driver
>>> * addressed feedback from Barnabás Pőcze[Thanks very much]
>>> * export privacy_valid to make the global state simpler to query
>>> * fix one issue which will block the dell-laptop driver to load when
>>>   privacy driver invalid
>>> * addressed feedback from Pierre-Louis Bossart,remove the EC ID match
>>> v2 -> v3:
>>> * add sysfs attributes doc
>>> v1 -> v2:
>>> * query EC handle from EC driver directly.
>>> * fix some code style.
>>> * add KEY_END to keymap array.
>>> * clean platform device when cleanup called
>>> * use hexadecimal format for log print in dev_dbg
>>> * remove __set_bit for the report keys from probe.
>>> * fix keymap leak
>>> * add err_free_keymap in dell_privacy_wmi_probe
>>> * wmi driver will be unregistered if privacy_acpi_init() fails
>>> * add sysfs attribute files for user space query.
>>> * add leds micmute driver to privacy acpi
>>> * add more design info the commit info
>>> ---
>>> ---
>>>  .../testing/sysfs-platform-dell-privacy-wmi   |  55 +++
>>>  drivers/platform/x86/dell/Kconfig             |  14 +
>>>  drivers/platform/x86/dell/Makefile            |   1 +
>>>  drivers/platform/x86/dell/dell-laptop.c       |  13 +-
>>>  drivers/platform/x86/dell/dell-privacy-wmi.c  | 394 ++++++++++++++++++
>>>  drivers/platform/x86/dell/dell-privacy-wmi.h  |  25 ++
>>>  drivers/platform/x86/dell/dell-wmi.c          |   9 +-
>>>  7 files changed, 507 insertions(+), 4 deletions(-)
>>>  create mode 100644 Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi
>>>  create mode 100644 drivers/platform/x86/dell/dell-privacy-wmi.c
>>>  create mode 100644 drivers/platform/x86/dell/dell-privacy-wmi.h
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi b/Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi
>>> new file mode 100644
>>> index 000000000000..7f9e18705861
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi
>>> @@ -0,0 +1,55 @@
>>> +What:		/sys/bus/wmi/devices/6932965F-1671-4CEB-B988-D3AB0A901919/dell_privacy_supported_type
>>> +Date:		Apr 2021
>>> +KernelVersion:	5.13
>>> +Contact:	"perry.yuan@dell.com>"
>>> +Description:
>>> +		Display which dell hardware level privacy devices are supported
>>> +		“Dell Privacy” is a set of HW, FW, and SW features to enhance
>>> +		Dell’s commitment to platform privacy for MIC, Camera, and
>>> +		ePrivacy screens.
>>> +		The supported hardware privacy devices are:
>>> +Attributes:
>>> +		Microphone Mute:
>>> +				Identifies the local microphone can be muted by hardware, no applications
>>> +				is available to capture system mic sound
>>> +
>>> +		Camera Shutter:
>>> +				Identifies camera shutter controlled by hardware, which is a micromechanical
>>> +				shutter assembly that is built onto the camera module to block capturing images
>>> +				from outside the laptop
>>> +
>>> +		supported:
>>> +				The privacy device is supported by this system
>>> +
>>> +		unsupported:
>>> +				The privacy device is not supported on this system
>>> +
>>> +		For example to check which privacy devices are supported:
>>> +
>>> +		# cat /sys/bus/wmi/drivers/dell-privacy/6932965F-1671-4CEB-B988-D3AB0A901919/dell_privacy_supported_type
>>> +		[Microphone Mute] [supported]
>>> +		[Camera Shutter] [supported]
>>> +		[ePrivacy Screen] [unsupported]
>>> +
>>> +What:		/sys/bus/wmi/devices/6932965F-1671-4CEB-B988-D3AB0A901919/dell_privacy_current_state
>>> +Date:		Apr 2021
>>> +KernelVersion:	5.13
>>> +Contact:	"perry.yuan@dell.com>"
>>> +Description:
>>> +		Allow user space to check current dell privacy device state.
>>> +		Describes the Device State class exposed by BIOS which can be
>>> +		consumed by various applications interested in knowing the Privacy
>>> +		feature capabilities
>>> +Attributes:
>>> +		muted:
>>> +			Identifies the privacy device is turned off and cannot send stream to OS applications
>>> +
>>> +		unmuted:
>>> +			Identifies the privacy device is turned on ,audio or camera driver can get
>>> +			stream from mic and camera module to OS applications
>>> +
>>> +		For example to check all supported current privacy device states:
>>> +
>>> +		# cat /sys/bus/wmi/drivers/dell-privacy/6932965F-1671-4CEB-B988-D3AB0A901919/dell_privacy_current_state
>>> +		[Microphone] [unmuted]
>>> +		[Camera Shutter] [unmuted]
>>> diff --git a/drivers/platform/x86/dell/Kconfig b/drivers/platform/x86/dell/Kconfig
>>> index e0a55337f51a..be570ccbbce0 100644
>>> --- a/drivers/platform/x86/dell/Kconfig
>>> +++ b/drivers/platform/x86/dell/Kconfig
>>> @@ -204,4 +204,18 @@ config DELL_WMI_SYSMAN
>>>  	  To compile this driver as a module, choose M here: the module will
>>>  	  be called dell-wmi-sysman.
>>>  
>>> +config DELL_PRIVACY
>>> +	tristate "Dell Hardware Privacy Support"
>>> +	depends on ACPI
>>> +	depends on ACPI_WMI
>>> +	depends on INPUT
>>> +	depends on DELL_LAPTOP
>>> +	depends on LEDS_TRIGGER_AUDIO
>>> +	depends on DELL_WMI
>>> +	help
>>> +	  This driver provides integration with the "Dell Hardware Privacy" feature
>>> +	  of Dell laptops.
>>> +
>>> +	  To compile this driver as a module, choose M here: the module will
>>> +	  be called dell_privacy.
>>>  endif # X86_PLATFORM_DRIVERS_DELL
>>> diff --git a/drivers/platform/x86/dell/Makefile b/drivers/platform/x86/dell/Makefile
>>> index d720a3e42ae3..7da0c33dfcca 100644
>>> --- a/drivers/platform/x86/dell/Makefile
>>> +++ b/drivers/platform/x86/dell/Makefile
>>> @@ -19,3 +19,4 @@ obj-$(CONFIG_DELL_WMI_AIO)		+= dell-wmi-aio.o
>>>  obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
>>>  obj-$(CONFIG_DELL_WMI_LED)		+= dell-wmi-led.o
>>>  obj-$(CONFIG_DELL_WMI_SYSMAN)		+= dell-wmi-sysman/
>>> +obj-$(CONFIG_DELL_PRIVACY)              += dell-privacy-wmi.o
>>> diff --git a/drivers/platform/x86/dell/dell-laptop.c b/drivers/platform/x86/dell/dell-laptop.c
>>> index 70edc5bb3a14..529547fb0cb1 100644
>>> --- a/drivers/platform/x86/dell/dell-laptop.c
>>> +++ b/drivers/platform/x86/dell/dell-laptop.c
>>> @@ -31,6 +31,8 @@
>>>  #include "dell-rbtn.h"
>>>  #include "dell-smbios.h"
>>>  
>>> +#include "dell-privacy-wmi.h"
>>> +
>>>  struct quirk_entry {
>>>  	bool touchpad_led;
>>>  	bool kbd_led_not_present;
>>> @@ -90,6 +92,7 @@ static struct rfkill *wifi_rfkill;
>>>  static struct rfkill *bluetooth_rfkill;
>>>  static struct rfkill *wwan_rfkill;
>>>  static bool force_rfkill;
>>> +static bool micmute_led_registered;
>>>  
>>>  module_param(force_rfkill, bool, 0444);
>>>  MODULE_PARM_DESC(force_rfkill, "enable rfkill on non whitelisted models");
>>> @@ -2205,11 +2208,13 @@ static int __init dell_init(void)
>>>  	dell_laptop_register_notifier(&dell_laptop_notifier);
>>>  
>>>  	if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
>>> -	    dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
>>> +	    dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE) &&
>>> +	    !dell_privacy_present()) {
>>>  		micmute_led_cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
>>>  		ret = led_classdev_register(&platform_device->dev, &micmute_led_cdev);
>>>  		if (ret < 0)
>>>  			goto fail_led;
>>> +		micmute_led_registered = true;
>>>  	}
>>>  
>>>  	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
>>> @@ -2257,7 +2262,8 @@ static int __init dell_init(void)
>>>  fail_get_brightness:
>>>  	backlight_device_unregister(dell_backlight_device);
>>>  fail_backlight:
>>> -	led_classdev_unregister(&micmute_led_cdev);
>>> +	if (micmute_led_registered)
>>> +		led_classdev_unregister(&micmute_led_cdev);
>>>  fail_led:
>>>  	dell_cleanup_rfkill();
>>>  fail_rfkill:
>>> @@ -2278,7 +2284,8 @@ static void __exit dell_exit(void)
>>>  		touchpad_led_exit();
>>>  	kbd_led_exit();
>>>  	backlight_device_unregister(dell_backlight_device);
>>> -	led_classdev_unregister(&micmute_led_cdev);
>>> +	if (micmute_led_registered)
>>> +		led_classdev_unregister(&micmute_led_cdev);
>>>  	dell_cleanup_rfkill();
>>>  	if (platform_device) {
>>>  		platform_device_unregister(platform_device);
>>> diff --git a/drivers/platform/x86/dell/dell-privacy-wmi.c b/drivers/platform/x86/dell/dell-privacy-wmi.c
>>> new file mode 100644
>>> index 000000000000..a32d0fbd99da
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/dell/dell-privacy-wmi.c
>>> @@ -0,0 +1,394 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * Dell privacy notification driver
>>> + *
>>> + * Copyright (C) 2021 Dell Inc. All Rights Reserved.
>>> + */
>>> +
>>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>> +
>>> +#include <linux/acpi.h>
>>> +#include <linux/bitops.h>
>>> +#include <linux/input.h>
>>> +#include <linux/input/sparse-keymap.h>
>>> +#include <linux/list.h>
>>> +#include <linux/leds.h>
>>> +#include <linux/module.h>
>>> +#include <linux/wmi.h>
>>> +
>>> +#include "dell-privacy-wmi.h"
>>> +
>>> +#define DELL_PRIVACY_GUID "6932965F-1671-4CEB-B988-D3AB0A901919"
>>> +#define MICROPHONE_STATUS		BIT(0)
>>> +#define CAMERA_STATUS		        BIT(1)
>>> +#define DELL_PRIVACY_AUDIO_EVENT  0x1
>>> +#define DELL_PRIVACY_CAMERA_EVENT 0x2
>>> +#define led_to_priv(c)       container_of(c, struct privacy_wmi_data, cdev)
>>> +
>>> +/*
>>> + * The wmi_list is used to store the privacy_priv struct with mutex protecting
>>> + */
>>> +static LIST_HEAD(wmi_list);
>>> +static DEFINE_MUTEX(list_mutex);
>>> +
>>> +struct privacy_wmi_data {
>>> +	struct input_dev *input_dev;
>>> +	struct wmi_device *wdev;
>>> +	struct list_head list;
>>> +	struct led_classdev cdev;
>>> +	u32 features_present;
>>> +	u32 last_status;
>>> +};
>>> +
>>> +/* DELL Privacy Type */
>>> +enum dell_hardware_privacy_type {
>>> +	DELL_PRIVACY_TYPE_AUDIO = 0,
>>> +	DELL_PRIVACY_TYPE_CAMERA,
>>> +	DELL_PRIVACY_TYPE_SCREEN,
>>> +	DELL_PRIVACY_TYPE_MAX,
>>> +};
>>> +
>>> +static const char * const privacy_types[DELL_PRIVACY_TYPE_MAX] = {
>>> +	[DELL_PRIVACY_TYPE_AUDIO] = "Microphone",
>>> +	[DELL_PRIVACY_TYPE_CAMERA] = "Camera Shutter",
>>> +	[DELL_PRIVACY_TYPE_SCREEN] = "ePrivacy Screen",
>>> +};
>>> +
>>> +/*
>>> + * Keymap for WMI privacy events of type 0x0012
>>> + */
>>> +static const struct key_entry dell_wmi_keymap_type_0012[] = {
>>> +	/* privacy mic mute */
>>> +	{ KE_KEY, 0x0001, { KEY_MICMUTE } },
>>> +	/* privacy camera mute */
>>> +	{ KE_SW,  0x0002, { SW_CAMERA_LENS_COVER } },
>>> +	{ KE_END, 0},
>>> +};
>>> +
>>> +/*
>>> + * global privacy state for other modules to query if the privacy driver loaded successfully
>>> + * or no privacy WMI device was detected at initial probe phase
>>> + */
>>> +bool dell_privacy_present(void)
>>> +{
>>> +	struct privacy_wmi_data *priv;
>>> +
>>> +	mutex_lock(&list_mutex);
>>> +	priv = list_first_entry_or_null(&wmi_list,
>>> +			struct privacy_wmi_data,
>>> +			list);
>>> +	mutex_unlock(&list_mutex);
>>> +
>>> +	return priv && (priv->features_present & BIT(DELL_PRIVACY_TYPE_AUDIO));
>>> +}
>>> +EXPORT_SYMBOL_GPL(dell_privacy_present);
>>> +
>>> +/*
>>> + * The flow of privacy event:
>>> + * 1) User presses key. HW does stuff with this key (timeout is started)
>>> + * 2) WMI event is emitted from BIOS
>>> + * 3) WMI event is received by dell-privacy
>>> + * 4) KEY_MICMUTE emitted from dell-privacy
>>> + * 5) Userland picks up key and modifies kcontrol for SW mute
>>> + * 6) Codec kernel driver catches and calls ledtrig_audio_set defined by
>>> + *    dell-privacy-acpi driver. Codec driver will call like this to switch micmute led state.
>>> + *    ledtrig_audio_set(LED_AUDIO_MICMUTE, micmute_led ? LED_ON :LED_OFF);
>>> + * 7) If "LED" is set to on dell-privacy notifies EC,and timeout is cancelled,
>>> + *	HW mic mute activated.
>>> + */
>>> +bool dell_privacy_process_event(int type, int code, int status)
>>> +{
>>> +	struct privacy_wmi_data *priv;
>>> +	const struct key_entry *key;
>>> +	bool ret = false;
>>> +
>>> +	mutex_lock(&list_mutex);
>>> +	priv = list_first_entry_or_null(&wmi_list,
>>> +			struct privacy_wmi_data,
>>> +			list);
>>> +	if (!priv)
>>> +		goto error;
>>> +
>>> +	key = sparse_keymap_entry_from_scancode(priv->input_dev, (type << 16) | code);
>>> +	if (!key) {
>>> +		dev_warn(&priv->wdev->dev, "Unknown key with type 0x%04x and code 0x%04x pressed\n",
>>> +			type, code);
>>> +		goto error;
>>> +	}
>>> +	dev_dbg(&priv->wdev->dev, "Key with type 0x%04x and code 0x%04x pressed\n", type, code);
>>> +
>>> +	switch (code) {
>>> +	case DELL_PRIVACY_AUDIO_EVENT: /* Mic mute */
>>> +	case DELL_PRIVACY_CAMERA_EVENT: /* Camera mute */
>>> +		priv->last_status = status;
>>> +		sparse_keymap_report_entry(priv->input_dev, key, 1, true);
>>> +		ret = true;
>>> +		break;
>>> +	default:
>>> +		dev_dbg(&priv->wdev->dev, "unknown event type 0x%04x 0x%04x\n", type, code);
>>> +	}
>>> +
>>> +error:
>>> +	mutex_unlock(&list_mutex);
>>> +	return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(dell_privacy_process_event);
>>> +
>>> +static ssize_t dell_privacy_supported_type_show(struct device *dev,
>>> +					struct device_attribute *attr,
>>> +					char *buf)
>>> +{
>>> +	struct privacy_wmi_data *priv = dev_get_drvdata(dev);
>>> +	enum dell_hardware_privacy_type type;
>>> +	u32 privacy_list;
>>> +	int len = 0;
>>> +
>>> +	privacy_list = priv->features_present;
>>> +	for (type = DELL_PRIVACY_TYPE_AUDIO; type < DELL_PRIVACY_TYPE_MAX; type++) {
>>> +		if (privacy_list & BIT(type))
>>> +			len += sysfs_emit_at(buf, len, "[%s] [supported]\n", privacy_types[type]);
>>> +		else
>>> +			len += sysfs_emit_at(buf, len, "[%s] [unsupported]\n", privacy_types[type]);
>>> +	}
>>> +
>>> +	return len;
>>> +}
>>> +
>>> +static ssize_t dell_privacy_current_state_show(struct device *dev,
>>> +					struct device_attribute *attr,
>>> +					char *buf)
>>> +{
>>> +	struct privacy_wmi_data *priv = dev_get_drvdata(dev);
>>> +	u32 privacy_supported = priv->features_present;
>>> +	enum dell_hardware_privacy_type type;
>>> +	u32 privacy_state = priv->last_status;
>>> +	int len = 0;
>>> +
>>> +	for (type = DELL_PRIVACY_TYPE_AUDIO; type < DELL_PRIVACY_TYPE_MAX; type++) {
>>> +		if (privacy_supported & BIT(type)) {
>>> +			if (privacy_state & BIT(type))
>>> +				len += sysfs_emit_at(buf, len, "[%s] [unmuted]\n", privacy_types[type]);
>>> +			else
>>> +				len += sysfs_emit_at(buf, len, "[%s] [muted]\n", privacy_types[type]);
>>> +		}
>>> +	}
>>> +
>>> +	return len;
>>> +}
>>> +
>>> +static DEVICE_ATTR_RO(dell_privacy_supported_type);
>>> +static DEVICE_ATTR_RO(dell_privacy_current_state);
>>> +
>>> +static struct attribute *privacy_attributes[] = {
>>> +	&dev_attr_dell_privacy_supported_type.attr,
>>> +	&dev_attr_dell_privacy_current_state.attr,
>>> +	NULL,
>>> +};
>>> +
>>> +static const struct attribute_group privacy_attribute_group = {
>>> +	.attrs = privacy_attributes
>>> +};
>>> +
>>> +/*
>>> + * Describes the Device State class exposed by BIOS which can be consumed by
>>> + * various applications interested in knowing the Privacy feature capabilities.
>>> + * class DeviceState
>>> + * {
>>> + *  [key, read] string InstanceName;
>>> + *  [read] boolean ReadOnly;
>>> + *
>>> + *  [WmiDataId(1), read] uint32 DevicesSupported;
>>> + *   0 - None; 0x1 - Microphone; 0x2 - Camera; 0x4 - ePrivacy  Screen
>>> + *
>>> + *  [WmiDataId(2), read] uint32 CurrentState;
>>> + *   0 - Off; 1 - On; Bit0 - Microphone; Bit1 - Camera; Bit2 - ePrivacyScreen
>>> + * };
>>> + */
>>> +static int get_current_status(struct wmi_device *wdev)
>>> +{
>>> +	struct privacy_wmi_data *priv = dev_get_drvdata(&wdev->dev);
>>> +	union acpi_object *obj_present;
>>> +	u32 *buffer;
>>> +	int ret = 0;
>>> +
>>> +	if (!priv) {
>>> +		dev_err(&wdev->dev, "dell privacy priv is NULL\n");
>>> +		return -EINVAL;
>>> +	}
>>> +	/* check privacy support features and device states */
>>> +	obj_present = wmidev_block_query(wdev, 0);
>>> +	if (!obj_present) {
>>> +		dev_err(&wdev->dev, "failed to read Binary MOF\n");
>>> +		return -EIO;
>>> +	}
>>> +
>>> +	if (obj_present->type != ACPI_TYPE_BUFFER) {
>>> +		dev_err(&wdev->dev, "Binary MOF is not a buffer!\n");
>>> +		ret = -EIO;
>>> +		goto obj_free;
>>> +	}
>>> +	/*  Although it's not technically a failure, this would lead to
>>> +	 *  unexpected behavior
>>> +	 */
>>> +	if (obj_present->buffer.length != 8) {
>>> +		dev_err(&wdev->dev, "Dell privacy buffer has unexpected length (%d)!\n",
>>> +				obj_present->buffer.length);
>>> +		ret = -EINVAL;
>>> +		goto obj_free;
>>> +	}
>>> +	buffer = (u32 *)obj_present->buffer.pointer;
>>> +	priv->features_present = buffer[0];
>>> +	priv->last_status = buffer[1];
>>> +
>>> +obj_free:
>>> +	kfree(obj_present);
>>> +	return ret;
>>> +}
>>> +
>>> +static int dell_privacy_micmute_led_set(struct led_classdev *led_cdev,
>>> +					enum led_brightness brightness)
>>> +{
>>> +	struct privacy_wmi_data *priv = led_to_priv(led_cdev);
>>> +	static char *acpi_method = (char *)"ECAK";
>>> +	acpi_status status;
>>> +	acpi_handle handle;
>>> +
>>> +	handle = ec_get_handle();
>>> +	if (!handle)
>>> +		return -EIO;
>>> +
>>> +	if (!acpi_has_method(handle, acpi_method))
>>> +		return -EIO;
>>> +
>>> +	status = acpi_evaluate_object(handle, acpi_method, NULL, NULL);
>>> +	if (ACPI_FAILURE(status)) {
>>> +		dev_err(&priv->wdev->dev, "Error setting privacy EC ack value: %s\n",
>>> +				acpi_format_exception(status));
>>> +		return -EIO;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +/*
>>> + * Pressing the mute key activates a time delayed circuit to physically cut
>>> + * off the mute. The LED is in the same circuit, so it reflects the true
>>> + * state of the HW mute.  The reason for the EC "ack" is so that software
>>> + * can first invoke a SW mute before the HW circuit is cut off.  Without SW
>>> + * cutting this off first does not affect the time delayed muting or status
>>> + * of the LED but there is a possibility of a "popping" noise.
>>> + *
>>> + * If the EC receives the SW ack, the circuit will be activated before the
>>> + * delay completed.
>>> + *
>>> + * Exposing as an LED device allows the codec drivers notification path to
>>> + * EC ACK to work
>>> + */
>>> +static int dell_privacy_leds_setup(struct device *dev)
>>> +{
>>> +	struct privacy_wmi_data *priv = dev_get_drvdata(dev);
>>> +
>>> +	priv->cdev.name = "dell-privacy::micmute";
>>> +	priv->cdev.max_brightness = 1;
>>> +	priv->cdev.brightness_set_blocking = dell_privacy_micmute_led_set;
>>> +	priv->cdev.default_trigger = "audio-micmute";
>>> +	priv->cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
>>> +	return devm_led_classdev_register(dev, &priv->cdev);
>>> +}
>>> +
>>> +static int dell_privacy_wmi_probe(struct wmi_device *wdev, const void *context)
>>> +{
>>> +	struct privacy_wmi_data *priv;
>>> +	struct key_entry *keymap;
>>> +	int ret, i;
>>> +
>>> +	ret = wmi_has_guid(DELL_PRIVACY_GUID);
>>> +	if (!ret)
>>> +		pr_debug("Unable to detect available Dell privacy devices!\n");
>>> +
>>> +	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
>>> +	if (!priv)
>>> +		return -ENOMEM;
>>> +
>>> +	dev_set_drvdata(&wdev->dev, priv);
>>> +	priv->wdev = wdev;
>>> +	/* create evdev passing interface */
>>> +	priv->input_dev = devm_input_allocate_device(&wdev->dev);
>>> +	if (!priv->input_dev)
>>> +		return -ENOMEM;
>>> +
>>> +	/* remap the wmi keymap event to new keymap */
>>> +	keymap = kcalloc(ARRAY_SIZE(dell_wmi_keymap_type_0012),
>>> +			sizeof(struct key_entry), GFP_KERNEL);
>>> +	if (!keymap)
>>> +		return -ENOMEM;
>>> +
>>> +	/* remap the keymap code with Dell privacy key type 0x12 as prefix
>>> +	 * KEY_MICMUTE scancode will be reported as 0x120001
>>> +	 */
>>> +	for (i = 0; i < ARRAY_SIZE(dell_wmi_keymap_type_0012); i++) {
>>> +		keymap[i] = dell_wmi_keymap_type_0012[i];
>>> +		keymap[i].code |= (0x0012 << 16);
>>> +	}
>>> +	ret = sparse_keymap_setup(priv->input_dev, keymap, NULL);
>>> +	kfree(keymap);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	priv->input_dev->dev.parent = &wdev->dev;
>>> +	priv->input_dev->name = "Dell Privacy Driver";
>>> +	priv->input_dev->id.bustype = BUS_HOST;
>>> +
>>> +	ret = input_register_device(priv->input_dev);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = get_current_status(priv->wdev);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = devm_device_add_group(&wdev->dev, &privacy_attribute_group);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	if (priv->features_present & BIT(DELL_PRIVACY_TYPE_AUDIO)) {
>>> +		ret = dell_privacy_leds_setup(&priv->wdev->dev);
>>> +		if (ret)
>>> +			return ret;
>>> +	}
>>> +	mutex_lock(&list_mutex);
>>> +	list_add_tail(&priv->list, &wmi_list);
>>> +	mutex_unlock(&list_mutex);
>>> +	return 0;
>>> +}
>>> +
>>> +static int dell_privacy_wmi_remove(struct wmi_device *wdev)
>>> +{
>>> +	struct privacy_wmi_data *priv = dev_get_drvdata(&wdev->dev);
>>> +
>>> +	mutex_lock(&list_mutex);
>>> +	list_del(&priv->list);
>>> +	mutex_unlock(&list_mutex);
>>> +	return 0;
>>> +}
>>> +
>>> +static const struct wmi_device_id dell_wmi_privacy_wmi_id_table[] = {
>>> +	{ .guid_string = DELL_PRIVACY_GUID },
>>> +	{ },
>>> +};
>>> +
>>> +static struct wmi_driver dell_privacy_wmi_driver = {
>>> +	.driver = {
>>> +		.name = "dell-privacy",
>>> +	},
>>> +	.probe = dell_privacy_wmi_probe,
>>> +	.remove = dell_privacy_wmi_remove,
>>> +	.id_table = dell_wmi_privacy_wmi_id_table,
>>> +};
>>> +
>>> +module_wmi_driver(dell_privacy_wmi_driver);
>>> +
>>> +MODULE_DEVICE_TABLE(wmi, dell_wmi_privacy_wmi_id_table);
>>> +MODULE_AUTHOR("Perry Yuan <perry_yuan@dell.com>");
>>> +MODULE_DESCRIPTION("Dell Privacy WMI Driver");
>>> +MODULE_LICENSE("GPL");
>>> diff --git a/drivers/platform/x86/dell/dell-privacy-wmi.h b/drivers/platform/x86/dell/dell-privacy-wmi.h
>>> new file mode 100644
>>> index 000000000000..54004eed7213
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/dell/dell-privacy-wmi.h
>>> @@ -0,0 +1,25 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>> +/*
>>> + * Dell privacy notification driver
>>> + *
>>> + * Copyright (C) 2021 Dell Inc. All Rights Reserved.
>>> + */
>>> +
>>> +#ifndef _DELL_PRIVACY_WMI_H_
>>> +#define _DELL_PRIVACY_WMI_H_
>>> +
>>> +#if IS_ENABLED(CONFIG_DELL_PRIVACY)
>>> +bool dell_privacy_present(void);
>>> +bool dell_privacy_process_event(int type, int code, int status);
>>> +#else /* CONFIG_DELL_PRIVACY */
>>> +static inline bool dell_privacy_present(void)
>>> +{
>>> +	return -ENODEV;
>>> +}
>>> +
>>> +static inline bool dell_privacy_process_event(int type, int code, int status)
>>> +{
>>> +	return false;
>>> +}
>>> +#endif /* CONFIG_DELL_PRIVACY */
>>> +#endif
>>> diff --git a/drivers/platform/x86/dell/dell-wmi.c b/drivers/platform/x86/dell/dell-wmi.c
>>> index bbdb3e860892..20367a580fa0 100644
>>> --- a/drivers/platform/x86/dell/dell-wmi.c
>>> +++ b/drivers/platform/x86/dell/dell-wmi.c
>>> @@ -27,6 +27,7 @@
>>>  #include <acpi/video.h>
>>>  #include "dell-smbios.h"
>>>  #include "dell-wmi-descriptor.h"
>>> +#include "dell-privacy-wmi.h"
>>>  
>>>  MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
>>>  MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
>>> @@ -427,7 +428,6 @@ static void dell_wmi_notify(struct wmi_device *wdev,
>>>  
>>>  		switch (buffer_entry[1]) {
>>>  		case 0x0000: /* One key pressed or event occurred */
>>> -		case 0x0012: /* Event with extended data occurred */
>>>  			if (len > 2)
>>>  				dell_wmi_process_key(wdev, buffer_entry[1],
>>>  						     buffer_entry[2]);
>>> @@ -439,6 +439,13 @@ static void dell_wmi_notify(struct wmi_device *wdev,
>>>  				dell_wmi_process_key(wdev, buffer_entry[1],
>>>  						     buffer_entry[i]);
>>>  			break;
>>> +		case 0x0012:
>>> +			if ((len > 4) && dell_privacy_process_event(buffer_entry[1], buffer_entry[3],
>>> +								    buffer_entry[4]))
>>> +				/* dell_privacy_process_event has handled the event */;
>>> +			else if (len > 2)
>>> +				dell_wmi_process_key(wdev, buffer_entry[1], buffer_entry[2]);
>>> +			break;
>>>  		default: /* Unknown event */
>>>  			pr_info("Unknown WMI event type 0x%x\n",
>>>  				(int)buffer_entry[1]);
>>>