platform/x86: dell-privacy: Add support for Dell hardware privacy

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
7) dell-privacy notifies EC, the timeout is cancelled and the HW mute
   is activated. If the EC is not notified then the HW mic mute will
   activate when the timeout triggers, just a bit later than with the
   active ack.
Signed-off-by: Perry Yuan <perry_yuan@dell.com>
Link: https://lore.kernel.org/r/20210506115605.1504-1-Perry_Yuan@Dell.com
[hdegoede@redhat.com: Rework Kconfig/Makefile bits + other small fixups]
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi

+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]

MAINTAINERS

@@ -5172,6 +5172,13 @@ M:	Pali Rohár <pali@kernel.org>
 S:	Maintained
 F:	drivers/platform/x86/dell/dell-wmi-base.c
 
+DELL WMI HARDWARE PRIVACY SUPPORT
+M:	Perry Yuan <Perry.Yuan@dell.com>
+L:	Dell.Client.Kernel@dell.com
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	drivers/platform/x86/dell/dell-wmi-privacy.c
+
 DELTA ST MEDIA DRIVER
 M:	Hugues Fruchet <hugues.fruchet@foss.st.com>
 L:	linux-media@vger.kernel.org

drivers/platform/x86/dell/Kconfig

@@ -53,6 +53,7 @@ config DELL_LAPTOP
 	depends on BACKLIGHT_CLASS_DEVICE
 	depends on ACPI_VIDEO || ACPI_VIDEO = n
 	depends on RFKILL || RFKILL = n
+	depends on DELL_WMI || DELL_WMI = n
 	depends on SERIO_I8042
 	depends on DELL_SMBIOS
 	select POWER_SUPPLY
@@ -164,6 +165,14 @@ config DELL_WMI
 	  To compile this driver as a module, choose M here: the module will
 	  be called dell-wmi.
 
+config DELL_WMI_PRIVACY
+	bool "Dell WMI Hardware Privacy Support"
+	depends on DELL_WMI
+	depends on LEDS_TRIGGER_AUDIO
+	help
+	  This option adds integration with the "Dell Hardware Privacy"
+	  feature of Dell laptops to the dell-wmi driver.
+
 config DELL_WMI_AIO
 	tristate "WMI Hotkeys for Dell All-In-One series"
 	default m

drivers/platform/x86/dell/Makefile

@@ -16,6 +16,7 @@ dell-smbios-$(CONFIG_DELL_SMBIOS_SMM)	+= dell-smbios-smm.o
 obj-$(CONFIG_DELL_SMO8800)		+= dell-smo8800.o
 obj-$(CONFIG_DELL_WMI)			+= dell-wmi.o
 dell-wmi-objs				:= dell-wmi-base.o
+dell-wmi-$(CONFIG_DELL_WMI_PRIVACY)	+= dell-wmi-privacy.o
 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

drivers/platform/x86/dell/dell-laptop.c

@@ -31,6 +31,8 @@
 #include "dell-rbtn.h"
 #include "dell-smbios.h"
 
+#include "dell-wmi-privacy.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_has_mic_mute()) {
 		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);

drivers/platform/x86/dell/dell-wmi-base.c

@@ -27,6 +27,7 @@
 #include <acpi/video.h>
 #include "dell-smbios.h"
 #include "dell-wmi-descriptor.h"
+#include "dell-wmi-privacy.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]);
@@ -747,6 +754,10 @@ static int __init dell_wmi_init(void)
 		}
 	}
 
+	err = dell_privacy_register_driver();
+	if (err)
+		return err;
+
 	return wmi_driver_register(&dell_wmi_driver);
 }
 late_initcall(dell_wmi_init);
@@ -757,6 +768,7 @@ static void __exit dell_wmi_exit(void)
 		dell_wmi_events_set_enabled(false);
 
 	wmi_driver_unregister(&dell_wmi_driver);
+	dell_privacy_unregister_driver();
 }
 module_exit(dell_wmi_exit);
 

drivers/platform/x86/dell/dell-wmi-privacy.h

+/* 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_WMI_PRIVACY)
+bool dell_privacy_has_mic_mute(void);
+bool dell_privacy_process_event(int type, int code, int status);
+int dell_privacy_register_driver(void);
+void dell_privacy_unregister_driver(void);
+#else /* CONFIG_DELL_PRIVACY */
+static inline bool dell_privacy_has_mic_mute(void)
+{
+	return false;
+}
+
+static inline bool dell_privacy_process_event(int type, int code, int status)
+{
+	return false;
+}
+
+static inline int dell_privacy_register_driver(void)
+{
+	return 0;
+}
+
+static inline void dell_privacy_unregister_driver(void)
+{
+}
+#endif /* CONFIG_DELL_PRIVACY */
+#endif