RE: [PATCH v5 1/2] platform/x86: dell-privacy: Add support for Dell hardware privacy

["Yuan, Perry" <Perry.Yuan@dell.com>]

Hi Hans.
Reviewing your feedback and working on next version below
 

> -----Original Message-----
> From: Hans de Goede <hdegoede@redhat.com>
> Sent: Wednesday, March 24, 2021 7:19 PM
> To: Yuan, Perry; pobrn@protonmail.com; pierre-
> louis.bossart@linux.intel.com; oder_chiou@realtek.com; perex@perex.cz;
> tiwai@suse.com; mgross@linux.intel.com; Limonciello, Mario
> Cc: lgirdwood@gmail.com; broonie@kernel.org; alsa-devel@alsa-project.org;
> linux-kernel@vger.kernel.org; platform-driver-x86@vger.kernel.org
> Subject: Re: [PATCH v5 1/2] platform/x86: dell-privacy: Add support for Dell
> hardware privacy
> 
> 
> [EXTERNAL EMAIL]
> 
> Hi,
> 
> On 3/22/21 10:38 AM, 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 emmits SW_CAMERA_LENS_COVER
> > event while the camera lens shutter will be changed by EC &
> > hw(hadware) 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.
> >
> > Signed-off-by: Perry Yuan <perry_yuan@dell.com>
> > ---
> > 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   |  32 ++
> >  drivers/platform/x86/dell/Kconfig             |  16 +
> >  drivers/platform/x86/dell/Makefile            |   3 +
> >  drivers/platform/x86/dell/dell-laptop.c       |  23 +-
> >  drivers/platform/x86/dell/dell-privacy-acpi.c | 164 +++++++++
> > drivers/platform/x86/dell/dell-privacy-wmi.c  | 340 ++++++++++++++++++
> > drivers/platform/x86/dell/dell-privacy-wmi.h  |  35 ++
> >  drivers/platform/x86/dell/dell-wmi.c          |  27 +-
> >  8 files changed, 627 insertions(+), 13 deletions(-)  create mode
> > 100644 Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi
> >  create mode 100644 drivers/platform/x86/dell/dell-privacy-acpi.c
> >  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..20c15a51ec38
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-platform-dell-privacy-wmi
> > @@ -0,0 +1,32 @@
> > +What:		/sys/bus/wmi/devices/6932965F-1671-4CEB-B988-
> D3AB0A901919/devices_supported
> > +Date:		Feb 2021
> > +KernelVersion:	5.12
> > +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:
> > +		- 0 = Not Supported
> > +		- 1 = Supported
> > +		- Bit0 -> Microphone
> > +		- Bit1 -> Camera
> > +		- Bit2 -> ePrivacy Screen
> > +
> > +What:		/sys/bus/wmi/devices/6932965F-1671-4CEB-B988-
> D3AB0A901919/current_state
> > +Date:		Feb 2021
> > +KernelVersion:	5.12
> > +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
> > +		There are three Bits for available states:
> > +		- 0 = Enabled
> > +		- 1 = Disabled
> 
> What is the definition of enabled/disabled ? Does enabled mean that the
> device is enabled, or that the device is in privacy mode, so in case of the
> microphone it is actually disabled (muted) ?
> 
> > +		- Bit0 -> Microphone
> > +		- Bit1 -> Camera
> > +		- Bit2 -> ePrivacyScreen
> > +
> 
> Normally we would use strings for something like this and not direclty export
> a bitfield, this would also allow avoiding the enabled / disabled ambiguity
> 
> E.g. you could have the following:
> 
> # supported devices
> $ cat /sys/bus/wmi/devices/6932965F-1671-4CEB-B988-
> D3AB0A901919/devices_supported
> Microphone Mute
> Camera Shutter
> ePrivacyScreen
> 
> # All devices in privacy mode:
> $ cat /sys/bus/wmi/devices/6932965F-1671-4CEB-B988-
> D3AB0A901919/current_state
> Microphone muted
> Camera Shutter closed
> ePrivacyScreen privacy-filter enabled
> 
> # All devices in non-privacy mode:
> 
> $ cat /sys/bus/wmi/devices/6932965F-1671-4CEB-B988-
> D3AB0A901919/current_state
> Microphone unmuted
> Camera Shutter open
> ePrivacyScreen privacy-filter disabled
> 
> You can easily do the bitfield -> string mapping in the kernel by having 3
> string arrays (support, privacy_on, privacy_off) indexed by the bitfield indices.
> 
> 
> > diff --git a/drivers/platform/x86/dell/Kconfig
> > b/drivers/platform/x86/dell/Kconfig
> > index e0a55337f51a..0e0f1eb35bd6 100644
> > --- a/drivers/platform/x86/dell/Kconfig
> > +++ b/drivers/platform/x86/dell/Kconfig
> > @@ -204,4 +204,20 @@ 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
> > +	select DELL_WMI
> > +	help
> > +	  This driver provides support for the "Dell Hardware Privacy" feature
> > +	  of Dell laptops.
> > +	  Support for a micmute and camera mute privacy will be provided as
> > +	  hardware button Ctrl+F4 and Ctrl+F9 hotkey.
> 
> This suggests that that the driver implements the buttons, which is not the
> case. How about:
> 
> 	  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..8b0883ee9412 100644
> > --- a/drivers/platform/x86/dell/Makefile
> > +++ b/drivers/platform/x86/dell/Makefile
> > @@ -19,3 +19,6 @@ 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.o
> > +dell-privacy-objs                       := dell-privacy-wmi.o \
> > +	                                   dell-privacy-acpi.o
> > diff --git a/drivers/platform/x86/dell/dell-laptop.c
> > b/drivers/platform/x86/dell/dell-laptop.c
> > index 70edc5bb3a14..4c840ab6cb59 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 has_privacy;
> >
> >  module_param(force_rfkill, bool, 0444);
> > MODULE_PARM_DESC(force_rfkill, "enable rfkill on non whitelisted
> > models"); @@ -2206,10 +2209,16 @@ static int __init dell_init(void)
> >
> >  	if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
> >  	    dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
> > -		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;
> > +		if (!privacy_valid)
> 
> This privacy_valid variable is coming from another module, so you're adding a
> "privacy_valid" symbol to the global kernel symbol namespace, even though
> this is dell specific. Please use the dell_privacy_present() function (see below)
> instead, so you get:
> 
> 		if (dell_privacy_present())
> 			has_privacy = true;
> 		else
> 			has_privacy = false;
> 
> Which makes much more sense then "if (!privacy_valid) has_privacy = true;"
> which feels as if it is inverted to what it should be.
> 
> > +			has_privacy = true;
> > +		else
> > +			has_privacy = false;
> > +		if (!has_privacy) {
> > +			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;
> > +		}
> >  	}
> >
> >  	if (acpi_video_get_backlight_type() != acpi_backlight_vendor) @@
> > -2257,7 +2266,8 @@ static int __init dell_init(void)
> >  fail_get_brightness:
> >  	backlight_device_unregister(dell_backlight_device);
> >  fail_backlight:
> > -	led_classdev_unregister(&micmute_led_cdev);
> > +	if (!has_privacy)
> > +		led_classdev_unregister(&micmute_led_cdev);
> >  fail_led:
> >  	dell_cleanup_rfkill();
> >  fail_rfkill:
> > @@ -2278,7 +2288,8 @@ 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 (!has_privacy)
> > +		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-acpi.c
> > b/drivers/platform/x86/dell/dell-privacy-acpi.c
> > new file mode 100644
> > index 000000000000..4c785b62c7c4
> > --- /dev/null
> > +++ b/drivers/platform/x86/dell/dell-privacy-acpi.c
> > @@ -0,0 +1,164 @@
> > +// 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/bits.h>
> > +#include <linux/device.h>
> > +#include <linux/fs.h>
> > +#include <linux/kernel.h>
> > +#include <linux/leds.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/string.h>
> > +#include <linux/sysfs.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +#include <linux/wmi.h>
> > +
> > +#include "dell-privacy-wmi.h"
> > +
> > +#define PRIVACY_PLATFORM_NAME	"dell-privacy-acpi"
> > +#define DELL_PRIVACY_GUID	"6932965F-1671-4CEB-B988-
> D3AB0A901919"
> > +
> > +struct privacy_acpi_priv {
> > +	struct device *dev;
> > +	struct platform_device *platform_device;
> > +	struct led_classdev cdev;
> > +};
> > +static struct privacy_acpi_priv *privacy_acpi;
> > +
> > +static int dell_privacy_micmute_led_set(struct led_classdev *led_cdev,
> > +		enum led_brightness brightness)
> > +{
> > +	struct privacy_acpi_priv *priv = privacy_acpi;
> 
> Please use container_of on the passed in led_cdev here instead of relying on
> a global variable.
> 
> > +	acpi_status status;
> > +	acpi_handle handle;
> > +	static char *acpi_method = (char *)"ECAK";
> > +
> > +	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->dev, "Error setting privacy EC ack value: %s\n",
> > +				acpi_format_exception(status));
> > +		return -EIO;
> > +	}
> > +	pr_debug("set dell privacy micmute ec ack event done\n");
> > +	return 0;
> > +}
> > +
> > +static int dell_privacy_acpi_remove(struct platform_device *pdev) {
> > +	struct privacy_acpi_priv *priv = dev_get_drvdata(privacy_acpi->dev);
> > +
> > +	led_classdev_unregister(&priv->cdev);
> > +
> > +	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_acpi_priv *priv = dev_get_drvdata(dev);
> > +	int ret = 0;
> > +
> > +	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);
> > +	ret = devm_led_classdev_register(dev, &priv->cdev);
> > +	if (ret)
> > +		return ret;
> > +	return 0;
> > +}
> > +
> > +static int dell_privacy_acpi_probe(struct platform_device *pdev) {
> > +	int ret;
> > +
> > +	platform_set_drvdata(pdev, privacy_acpi);
> > +	privacy_acpi->dev = &pdev->dev;
> > +	privacy_acpi->platform_device = pdev;
> > +
> > +	ret = dell_privacy_leds_setup(&pdev->dev);
> > +	if (ret)
> > +		return -EIO;
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver dell_privacy_platform_drv = {
> > +	.driver = {
> > +		.name = PRIVACY_PLATFORM_NAME,
> > +	},
> > +	.probe = dell_privacy_acpi_probe,
> > +	.remove = dell_privacy_acpi_remove,
> > +};
> > +
> > +int __init dell_privacy_acpi_init(void) {
> > +	int err;
> > +	struct platform_device *pdev;
> > +
> > +	if (!wmi_has_guid(DELL_PRIVACY_GUID))
> > +		return -ENODEV;
> > +
> > +	privacy_acpi = kzalloc(sizeof(*privacy_acpi), GFP_KERNEL);
> > +	if (!privacy_acpi)
> > +		return -ENOMEM;
> > +
> > +	err = platform_driver_register(&dell_privacy_platform_drv);
> > +	if (err)
> > +		goto pdrv_err;
> > +
> > +	pdev = platform_device_register_simple(
> > +			PRIVACY_PLATFORM_NAME,
> PLATFORM_DEVID_NONE, NULL, 0);
> > +	if (IS_ERR(pdev)) {
> > +		err = PTR_ERR(pdev);
> > +		goto pdev_err;
> > +	}
> 
> So you're creating a platform_device here, from code called from the
> init_dell_privacy() function in dell-privacy-wmi.c, just so that the probe()
> function for that platform-device can register the led_classdev for the
> (alternative) mute LED.
> 
> Please just put the cdev struct inside struct privacy_wmi_data and call
> dell_privacy_leds_setup() with the wmi-dev as parameter from
> dell_privacy_wmi_probe and have the wmi-dev as the parent of the
> led_classdev.
> 
> This allows removing both the platform-driver and the instantiation of the
> platform-device.
> 
> After removing the unnecessary platfrom-dev/driver there will be so little left
> of dell-privacy-acpi.c, that what remains can and should just be folded into
> dell-privacy-wmi.c. At which point you're down to one file for the module
> which also simplifies the Makefile.
> 
> > +
> > +	return 0;
> > +
> > +pdev_err:
> > +	platform_device_unregister(pdev);
> > +pdrv_err:
> > +	kfree(privacy_acpi);
> > +	return err;
> > +}
> > +
> > +void __exit dell_privacy_acpi_exit(void) {
> > +	struct platform_device *pdev =
> > +to_platform_device(privacy_acpi->dev);
> > +
> > +	platform_device_unregister(pdev);
> > +	platform_driver_unregister(&dell_privacy_platform_drv);
> > +	kfree(privacy_acpi);
> > +}
> > +
> > +MODULE_AUTHOR("Perry Yuan <perry_yuan@dell.com>");
> > +MODULE_DESCRIPTION("DELL Privacy ACPI Driver");
> > +MODULE_LICENSE("GPL");
> > 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..8bde97613477
> > --- /dev/null
> > +++ b/drivers/platform/x86/dell/dell-privacy-wmi.c
> > @@ -0,0 +1,340 @@
> > +// 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/input.h>
> > +#include <linux/input/sparse-keymap.h> #include <linux/list.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 PRIVACY_SCREEN_STATUS		BIT(2)
> > +
> > +/*
> > + * The wmi_list is used to store the privacy_priv struct with mutex
> > +protecting  */ static LIST_HEAD(wmi_list); static
> > +DEFINE_MUTEX(list_mutex);
> > +/*
> > + * 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  */
> > +int privacy_valid = -EPROBE_DEFER; EXPORT_SYMBOL_GPL(privacy_valid);
> 
> None of the callers are interpreting the error-codes stored here.
> So this is really treated as a bool, and the info stored in the bool is already
> available inside the wmi_list-head. So just drop this.
> 
> > +
> > +struct privacy_wmi_data {
> > +	struct input_dev *input_dev;
> > +	struct wmi_device *wdev;
> > +	struct list_head list;
> > +	u32 features_present;
> > +	u32 last_status;
> > +};
> > +
> > +/*
> > + * 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},
> > +};
> > +
> > +int dell_privacy_state(void)
> 
> Please rename this to dell_privacy_present(), "state" is very generic / not
> descriptive and use list_first_entry_or_null(&wmi_list) as done in
> dell_privacy_process_event(), e.g.:
> 
> 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;
> }
> 
> 
> 
> > +{
> > +	return privacy_valid;
> > +}
> > +EXPORT_SYMBOL_GPL(dell_privacy_state);
> > +/*
> > + * 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.
> > + */
> > +void dell_privacy_process_event(int type, int code, int status)
> 
> Please make this return a bool, returning true when it has consumed the
> event and false when it did not consume the event. This will allow other
> 0x0012 0xXXXX codes to still be handled by the existing dell-wmi.c code for
> this.
> 
> > +{
> > +	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) {
> > +		pr_err("dell privacy priv is NULL\n");
> > +		goto error;
> > +	}
> > +	key = sparse_keymap_entry_from_scancode(priv->input_dev, (type
> << 16) | code);
> > +	if (!key) {
> > +		dev_dbg(&priv->wdev->dev, "Unknown key with type 0x%04x
> and code 0x%04x pressed\n",
> > +				type, code);
> > +		goto error;
> > +	}
> > +	switch (code) {
> > +	case DELL_PRIVACY_TYPE_AUDIO: /* Mic mute */
> > +		priv->last_status = status;
> > +		sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> 
> 		ret = true;
> 
> > +		break;
> > +	case DELL_PRIVACY_TYPE_CAMERA: /* Camera mute */
> > +		priv->last_status = status;
> > +		sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> 
> 		ret = true;
> 
> > +		break;
> 
> These 2 cases are exactly the same, please merge them into a single case.
> 
> > +	default:
> > +		dev_dbg(&priv->wdev->dev, "unknown event type 0x%04x
> 0x%04x",
> > +				type, code);
> > +	}
> > +
> > +error:
> > +	mutex_unlock(&list_mutex);
> 
> 	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dell_privacy_process_event);
> > +
> > +static ssize_t devices_supported_show(struct device *dev,
> > +		struct device_attribute *attr,
> > +		char *buf)
> > +{
> > +	struct privacy_wmi_data *priv = dev_get_drvdata(dev);
> > +
> > +	return sysfs_emit(buf, "%x\n", priv->features_present); }
> > +
> > +static ssize_t current_state_show(struct device *dev,
> > +		struct device_attribute *attr,
> > +		char *buf)
> > +{
> > +	struct privacy_wmi_data *priv = dev_get_drvdata(dev);
> > +
> > +	return sysfs_emit(buf, "%x\n", priv->last_status); }
> 
> Please change these to emit strings as discussed above (assuming you agree
> with my above proposal for this).
> 
> > +
> > +static DEVICE_ATTR_RO(devices_supported);
> > +static DEVICE_ATTR_RO(current_state);
> > +
> > +static struct attribute *privacy_attributes[] = {
> > +	&dev_attr_devices_supported.attr,
> > +	&dev_attr_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) {
> > +		pr_err("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");
> > +		ret = -EIO;
> > +		privacy_valid = ret;
> > +		return ret;
> > +	}
> > +
> > +	if (obj_present->type != ACPI_TYPE_BUFFER) {
> > +		dev_err(&wdev->dev, "Binary MOF is not a buffer!\n");
> > +		ret = -EIO;
> > +		privacy_valid = ret;
> > +		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;
> > +		privacy_valid = ret;
> > +		goto obj_free;
> > +	}
> > +	buffer = (u32 *)obj_present->buffer.pointer;
> > +	priv->features_present = buffer[0];
> > +	priv->last_status = buffer[1];
> > +	privacy_valid = 0;
> 
> As discussed, there is no need for the privacy_valid variable, remove all
> references to it here.
> 
> > +
> > +obj_free:
> > +	kfree(obj_present);
> > +	return ret;
> > +}
> > +
> > +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;
> > +
> > +	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) {
> > +		ret = -ENOMEM;
> > +		goto err_free_dev;
> > +	}
> 
> No need for the goto here just simplify this to:
> 
> 	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);
> 
> You're done with the keymap here, please put a single:
> 
> 	kfree(keymap);
> 
> Here before the if (ret), then you won't need any goto style cleanup
> anywhere in this function.
> 
> This also fixes not free-ing the keymap when sparse_keymap_setup() fails.
> 
> > +	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;
> > +	if (input_register_device(priv->input_dev)) {
> > +		pr_debug("input_register_device failed to register!\n");
> 
> You're not setting ret here.
> 
> > +		goto err_free_keymap;
> > +	}
> 
> No need for the pr_debug, the kernel will already complain if this fails.
> Also since all your resources are devm managed and we've already taken care
> of the keymap this can be simplified to:
> 
> 	ret = input_register_device(priv->input_dev);
> 	if (ret)
> 		returm ret;
> 
> > +	mutex_lock(&list_mutex);
> > +	list_add_tail(&priv->list, &wmi_list);
> > +	mutex_unlock(&list_mutex);
> 
> Move this to directly above the return 0; below, see below.
> 
> > +
> > +	if (get_current_status(priv->wdev))
> > +		goto err_free_input;
> 
> You're again not setting ret here before the goto.
> 
> And you are returning with an error here after adding the device to the
> wmi_list, the list_add_tail call should be done last, directly above the return 0
> call.
> 
> Also since all your resources are devm managed and we've already taken care
> of the keymap this can be simplified to:
> 
> 	ret = get_current_status(priv->wdev);
> 	if (ret)
> 		return ret;
> 
> > +
> > +	ret = devm_device_add_group(&wdev->dev,
> &privacy_attribute_group);
> > +	if (ret)
> > +		goto err_free_input;
> 
> Replace the goto err_free_input() with return ret;
> 
> > +
> > +	kfree(keymap);
> 
> Drop this kfree() (already done above now).
> 
> Move the list_add_tail() here.
> 
> > +	return 0;
> > +
> > +err_free_input:
> > +	input_unregister_device(priv->input_dev);
> 
> This is not necessary for an input_device allocated with
> devm_input_allocate_device(), which means that none of these error
> handling labels are necessary now, so this can all be removed.
> 
> 
> 
> > +err_free_keymap:
> > +	privacy_valid = -ENODEV;
> > +	kfree(keymap);
> > +err_free_dev:
> > +	return ret;
> > +}
> > +
> > +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);
> > +	privacy_valid = -ENODEV;
> > +	input_unregister_device(priv->input_dev);
> 
> The input_unregister is not necessary (and privacy_valid is gone too).
> 
> > +
> > +	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, };
> > +
> > +static int __init init_dell_privacy(void) {
> > +	int ret;
> > +
> > +	ret = wmi_has_guid(DELL_PRIVACY_GUID);> +	if (!ret) {
> > +		privacy_valid = -ENODEV;
> > +		pr_debug("Unable to detect available Dell privacy
> devices: %d\n", ret);
> > +		return privacy_valid;
> > +	}
> 
> This driver will only get modprobed if the GUID is present and when it is not
> present then loading the driver is a no-op so this can be checked.
> 
> > +
> > +	ret = wmi_driver_register(&dell_privacy_wmi_driver);
> > +	if (ret) {
> > +		pr_err("failed to initialize privacy wmi driver: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = dell_privacy_acpi_init();
> > +	if (ret) {
> > +		pr_err("failed to initialize privacy acpi driver: %d\n", ret);
> > +		goto err_init;
> > +	}
> 
> And with the platform-device/driver removed this is not necessary too, which
> means ...
> 
> > +
> > +	return 0;
> > +
> > +err_init:
> > +	wmi_driver_unregister(&dell_privacy_wmi_driver);
> > +	return ret;
> > +}
> > +
> > +static void dell_privacy_wmi_exit(void) {
> > +	wmi_driver_unregister(&dell_privacy_wmi_driver);
> > +}
> > +
> > +static void __exit exit_dell_privacy(void) {
> > +	dell_privacy_wmi_exit();
> > +	dell_privacy_acpi_exit();
> > +}
> > +
> > +module_init(init_dell_privacy);
> > +module_exit(exit_dell_privacy);
> 
> That all of the init_dell_privacy / exit_dell_privacy stuff can be replaced with
> a single line:
> 
> 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..6dda2990df5d
> > --- /dev/null
> > +++ b/drivers/platform/x86/dell/dell-privacy-wmi.h
> > @@ -0,0 +1,35 @@
> > +/* 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)
> > +extern int privacy_valid;
> 
> Please remove this from the global kernel namespace (make it a static global
> inside the dell-privacy-wmi.c code).
> 
> > +int  dell_privacy_state(void);
> > +void dell_privacy_process_event(int type, int code, int status);
> > +#else /* CONFIG_DELL_PRIVACY */ int privacy_valid = -ENODEV;
> 
> Drop this.
> 
> > +static inline int dell_privacy_state(void) {
> > +	return privacy_valid;
> 
> And directly return -ENODEV here.
> 
> > +}
> > +
> > +static inline void dell_privacy_process_event(int type, int code, int
> > +status) {} #endif /* CONFIG_DELL_PRIVACY */
> > +
> > +int  dell_privacy_acpi_init(void);
> > +void dell_privacy_acpi_exit(void);
> > +
> > +/* DELL Privacy Type */
> > +enum {
> > +	DELL_PRIVACY_TYPE_UNKNOWN = 0x0,
> > +	DELL_PRIVACY_TYPE_AUDIO,
> > +	DELL_PRIVACY_TYPE_CAMERA,
> > +};
> 
> This enum is only used inside dell-privacy-wmi.c, please move it there.
> 
> > +#endif
> 
> With the platform-device/driver removal discussed above all this header file
> needs to do is defines the prototypes / stubs for 2 functions:
> 
> int  dell_privacy_state(void);
> void dell_privacy_process_event(int type, int code, int status);
> 
> I think it would be best to just add these to dell-smbios.h, rather then adding
> a new header just for these 2 prototypes / stubs.
> 
> 
> > diff --git a/drivers/platform/x86/dell/dell-wmi.c
> > b/drivers/platform/x86/dell/dell-wmi.c
> > index bbdb3e860892..389e86de24b0 100644
> > --- a/drivers/platform/x86/dell/dell-wmi.c
> > +++ b/drivers/platform/x86/dell/dell-wmi.c
> > @@ -13,20 +13,22 @@
> >
> >  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> >
> > -#include <linux/kernel.h>
> > -#include <linux/module.h>
> > +#include <linux/acpi.h>
> > +#include <linux/dmi.h>
> >  #include <linux/init.h>
> > -#include <linux/slab.h>
> > -#include <linux/types.h>
> >  #include <linux/input.h>
> >  #include <linux/input/sparse-keymap.h> -#include <linux/acpi.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> >  #include <linux/string.h>
> > -#include <linux/dmi.h>
> > +#include <linux/types.h>
> >  #include <linux/wmi.h>
> >  #include <acpi/video.h>
> > +
> 
> Please split the changes sorting these includes alphabetically out into a
> separate cleanup patch.
> 
> >  #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>"); @@ -381,6 +383,7
> @@
> > static void dell_wmi_notify(struct wmi_device *wdev,
> >  	u16 *buffer_entry, *buffer_end;
> >  	acpi_size buffer_size;
> >  	int len, i;
> > +	int err;
> 
> Drop this.
> 
> >
> >  	if (obj->type != ACPI_TYPE_BUFFER) {
> >  		pr_warn("bad response type %x\n", obj->type); @@ -427,7
> +430,6 @@
> > 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 +441,17 @@ static void dell_wmi_notify(struct wmi_device
> *wdev,
> >  				dell_wmi_process_key(wdev, buffer_entry[1],
> >  						     buffer_entry[i]);
> >  			break;
> > +		case 0x0012:
> > +			err = dell_privacy_state();
> > +			if (err == 0) {
> > +				dell_privacy_process_event(buffer_entry[1],
> > +							   buffer_entry[3],
> buffer_entry[4]);
> 
> This needs a len > 4 check !
> 
> > +			} else {
> > +				if (len > 2)
> > +					dell_wmi_process_key(wdev,
> buffer_entry[1],
> > +							     buffer_entry[2]);
> > +			}
> 
> Combined with the change to have dell_privacy_process_event() return a
> bool, this should look something like this:
> 
> 			if (len > 4 &&
> dell_privacy_process_event(buffer_entry[1], buffer_entry[3], buffer_entry[4]))
> 				; /* Handled by dell_privacy_process_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]);
> >
> 
> Regards,
> 
> Hans