Date:   Mon, 28 Dec 2020 20:26:22 +0000
From:   Barnabás Pőcze <pobrn@...tonmail.com>
To:     Perry Yuan <Perry.Yuan@...l.com>
Cc:     "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "mgross@...ux.intel.com" <mgross@...ux.intel.com>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Limonciello Mario <Mario.Limonciello@...l.com>
Subject: Re: [PATCH v2 1/2] platform/x86: dell-privacy: Add support for Dell hardware privacy

Hi


Firstly, a minor note: the newly created sysfs attributes are not documented, so
I believe you should either move them to debugfs or add documentation. And I
believe you might have forgotten to send the second patch in the series.

I added a couple comments regarding the code, but unfortunately I believe there
are deeper, architectural problems. I cannot help but think that this is a bit
over-complicated with its 1 platform device, 1 platform driver, 1 WMI driver,
2 source files, not-immediately-clear relationship between the two "submodules",
and (a bit) forced integration with the dell-wmi module.

If it were up to me I would do it the simplest way: a single module,
exports dell_privacy_is_ok() and dell_privacy_event(); its probe checks the WMI
GUID, the EC handle, and the ECAK method; registers a single platform device
with PLATFORM_DEVID_NONE and with the necessary attributes (devices_supported,
current_state); registers the LED and input device under the platform device.

But, of course, you should wait for Hans or Mark to see what they'd prefer.


2020. december 28., hétfő 14:28 keltezéssel, Perry Yuan írta:

> From: Perry Yuan <perry_yuan@...l.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 enabled, 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.

I believe at the first occurrence of "EC" it should be noted what it stands for.


> and camera mute hotkey is ctrl+F9.currently design only emmit
> SW_CAMERA_LENS_COVER event while the camera LENS shutter will be

Why is "LENS" capitalized?


> changed by EC & HW control.
>
> *The flow is like this:
> 1) User presses key. HW does stuff with this key (timeout is started)
> 2) Event is emitted from FW
> 3) Event 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.
>

Please proofread the commit message again, and pay attention to capitalization
and spacing.


> Signed-off-by: Perry Yuan  <perry_yuan@...l.com>
> Signed-off-by: Limonciello Mario <mario_limonciello@...l.com>
> ---
> 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
> ---
> ---
>  drivers/platform/x86/Kconfig             |  17 ++
>  drivers/platform/x86/Makefile            |   4 +-
>  drivers/platform/x86/dell-laptop.c       |  29 ++-
>  drivers/platform/x86/dell-privacy-acpi.c | 165 ++++++++++++
>  drivers/platform/x86/dell-privacy-wmi.c  | 309 +++++++++++++++++++++++
>  drivers/platform/x86/dell-privacy-wmi.h  |  33 +++
>  drivers/platform/x86/dell-wmi.c          |  26 +-
>  7 files changed, 567 insertions(+), 16 deletions(-)
>  create mode 100644 drivers/platform/x86/dell-privacy-acpi.c
>  create mode 100644 drivers/platform/x86/dell-privacy-wmi.c
>  create mode 100644 drivers/platform/x86/dell-privacy-wmi.h
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 91e6176cdfbd..9d5cc2454b3e 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -491,6 +491,23 @@ config DELL_WMI_LED
>  	  This adds support for the Latitude 2100 and similar
>  	  notebooks that have an external LED.
>
> +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
> +
> +	To compile this driver as a module, choose M here: the module will
> +	be called dell_privacy.
> +
>  config AMILO_RFKILL
>  	tristate "Fujitsu-Siemens Amilo rfkill support"
>  	depends on RFKILL
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 581475f59819..18c430456de7 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -51,7 +51,9 @@ obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
>  obj-$(CONFIG_DELL_WMI_AIO)		+= dell-wmi-aio.o
>  obj-$(CONFIG_DELL_WMI_LED)		+= dell-wmi-led.o
>  obj-$(CONFIG_DELL_WMI_SYSMAN)		+= dell-wmi-sysman/
> -
> +obj-$(CONFIG_DELL_PRIVACY)              += dell-privacy.o
> +dell-privacy-objs                       := dell-privacy-wmi.o \
> +	                                   dell-privacy-acpi.o
>  # Fujitsu
>  obj-$(CONFIG_AMILO_RFKILL)	+= amilo-rfkill.o
>  obj-$(CONFIG_FUJITSU_LAPTOP)	+= fujitsu-laptop.o
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index 70edc5bb3a14..ea0c8a8099ff 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -30,6 +30,7 @@
>  #include <acpi/video.h>
>  #include "dell-rbtn.h"
>  #include "dell-smbios.h"
> +#include "dell-privacy-wmi.h"
>
>  struct quirk_entry {
>  	bool touchpad_led;
> @@ -90,6 +91,7 @@ static struct rfkill *wifi_rfkill;
>  static struct rfkill *bluetooth_rfkill;
>  static struct rfkill *wwan_rfkill;
>  static bool force_rfkill;
> +static bool privacy_valid;
>
>  module_param(force_rfkill, bool, 0444);
>  MODULE_PARM_DESC(force_rfkill, "enable rfkill on non whitelisted models");
> @@ -1587,10 +1589,10 @@ static ssize_t kbd_led_timeout_store(struct device *dev,
>  		switch (unit) {
>  		case KBD_TIMEOUT_DAYS:
>  			value *= 24;
> -			fallthrough;
> +			/* fall through */
>  		case KBD_TIMEOUT_HOURS:
>  			value *= 60;
> -			fallthrough;
> +			/* fall through */

What is the reason behind changing "fallthrough;" to a comment?


>  		case KBD_TIMEOUT_MINUTES:
>  			value *= 60;
>  			unit = KBD_TIMEOUT_SECONDS;
> @@ -2205,11 +2207,18 @@ 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)) {
> -		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;
> +			dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
> +#if IS_ENABLED(CONFIG_DELL_PRIVACY)
> +		ret = dell_privacy_valid();
> +		if (!ret)
> +			privacy_valid = true;
> +#endif
> +		if (!privacy_valid) {
> +			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 (!privacy_valid)
> +		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 (!privacy_valid)
> +		led_classdev_unregister(&micmute_led_cdev);
>  	dell_cleanup_rfkill();
>  	if (platform_device) {
>  		platform_device_unregister(platform_device);
> diff --git a/drivers/platform/x86/dell-privacy-acpi.c b/drivers/platform/x86/dell-privacy-acpi.c
> new file mode 100644
> index 000000000000..fef781555b67
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-acpi.c
> @@ -0,0 +1,165 @@
> +// 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/device.h>
> +#include <linux/fs.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/string.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +#include <linux/wmi.h>
> +#include <linux/slab.h>
> +#include <linux/bits.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include "dell-privacy-wmi.h"

I believe it would be preferable to sort the list of includes lexicographically.
("dell-privacy-wmi.h" can remain separate)


> +
> +#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;

Any reason it needs to be dynamically allocated?


> +
> +static int dell_privacy_micmute_led_set(struct led_classdev *led_cdev,
> +		enum led_brightness brightness)
> +{
> +	struct privacy_acpi_priv *priv = privacy_acpi;
> +	acpi_status status;
> +	acpi_handle handle;
> +	char *acpi_method;
> +
> +	handle = ec_get_handle();
> +	if (!handle)
> +		return -EIO;
> +	if (acpi_has_method(handle, "ECAK"))
> +		acpi_method = "ECAK";
> +	else
> +		return -ENODEV;

I find this if-else a bit cumbersome. Any reason why

if (!acpi_has_method(handle, "ECAK"))
  return ...;

would not work? I believe you could also easily do away with the `acpi_method`
variable.


> +
> +	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;
> +	}
> +	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);
> +	dev_set_drvdata(&pdev->dev, NULL);

This is not needed as the driver sets the driver data to NULL when a driver
unbinds from a device.


> +
> +	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 void dell_privacy_leds_setup(struct device *dev)
> +{
> +	struct privacy_acpi_priv *priv = dev_get_drvdata(dev);
> +
> +	priv->cdev.name = "privacy::micmute";

Maybe "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);
> +	priv->cdev.dev = dev;

There is no need for this assignment.


> +	devm_led_classdev_register(dev, &priv->cdev);

I believe it'd be preferable to return the return value of this call.


> +}
> +
> +static int dell_privacy_acpi_probe(struct platform_device *pdev)
> +{
> +	platform_set_drvdata(pdev, privacy_acpi);
> +	privacy_acpi->dev = &pdev->dev;
> +	privacy_acpi->platform_device = pdev;
> +	return 0;
> +}
> +
> +static const struct acpi_device_id privacy_acpi_device_ids[] = {
> +	{"PNP0C09", 0},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, privacy_acpi_device_ids);
> +
> +static struct platform_driver dell_privacy_platform_drv = {
> +	.driver = {
> +		.name = PRIVACY_PLATFORM_NAME,
> +		.acpi_match_table = ACPI_PTR(privacy_acpi_device_ids),
> +	},
> +	.remove = dell_privacy_acpi_remove,
> +};

I think using a platform driver here just complicates things for no reason.
Furthermore, I'm not sure if there's actually any need for the ACPI match table.


> +
> +int dell_privacy_acpi_init(void)

I believe this could be marked __init.


> +{
> +	int err;
> +	struct platform_device *pdev;
> +	int privacy_capable = wmi_has_guid(DELL_PRIVACY_GUID);
> +
> +	if (!privacy_capable)

It could just be `if (!wmi_has_guid(...))`.


> +		return -ENODEV;
> +
> +	privacy_acpi = kzalloc(sizeof(struct privacy_acpi_priv), GFP_KERNEL);

Please use `sizeof(*privacy_acpi)`.


> +	if (!privacy_acpi)
> +		return -ENOMEM;
> +
> +	pdev = platform_device_register_simple(
> +			PRIVACY_PLATFORM_NAME, -1, NULL, 0);

Please use `PLATFORM_DEVID_NONE` instead of -1.


> +	if (IS_ERR(pdev)) {
> +		err = PTR_ERR(pdev);
> +		goto pdev_err;
> +	}
> +	err = platform_driver_probe(&dell_privacy_platform_drv,
> +			dell_privacy_acpi_probe);

What is the reason for preferring this instead of specifying the probe callback
in the platform_driver struct and registering it?


> +	if (err)
> +		goto pdrv_err;
> +
> +	dell_privacy_leds_setup(&pdev->dev);

I think you should check if the call succeeds or not.


> +
> +	return 0;
> +
> +pdrv_err:
> +	platform_device_unregister(pdev);
> +pdev_err:
> +	kfree(privacy_acpi);
> +	return err;
> +}
> +
> +void dell_privacy_acpi_exit(void)

I believe this could be marked __exit.


> +{
> +	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@...l.com>");
> +MODULE_DESCRIPTION("DELL Privacy ACPI Driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/platform/x86/dell-privacy-wmi.c b/drivers/platform/x86/dell-privacy-wmi.c
> new file mode 100644
> index 000000000000..80637c7f617c
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-wmi.c
> @@ -0,0 +1,309 @@
> +// 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)
> +
> +static int privacy_valid = -EPROBE_DEFER;

I think it'd be better `privacy_valid` was a `bool` (or maybe an enum):

```
enum dell_privacy_state {
	DELL_PRIVACY_STATE_OK,
	DELL_PRIVACY_STATE_NOK,
	DELL_PRIVACY_STATE_UNKNOWN,
};
```

or something similar.


> +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;
> +	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 */

Any reason for "MIC" being capitalized?


> +	{ KE_KEY, 0x0001, { KEY_MICMUTE } },
> +	/* Privacy Camera Mute */
> +	{ KE_SW,  0x0002, { SW_CAMERA_LENS_COVER } },
> +	{ KE_END, 0},
> +};
> +
> +int dell_privacy_valid(void)
> +{
> +	int ret;
> +
> +	ret = wmi_has_guid(DELL_PRIVACY_GUID);
> +	if (!ret)
> +		return -ENODEV;
> +	ret = privacy_valid;
> +	return ret;

I find this function really confusing, and too verbose for what it does.


> +}
> +EXPORT_SYMBOL_GPL(dell_privacy_valid);
> +
> +void dell_privacy_process_event(int type, int code, int status)
> +{
> +	struct privacy_wmi_data *priv;
> +	const struct key_entry *key;
> +
> +	mutex_lock(&list_mutex);
> +	priv = list_first_entry_or_null(&wmi_list,
> +			struct privacy_wmi_data,
> +			list);

Can you please explain why this list is needed if only the first entry will
ever be used?


> +	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);
> +		break;
> +	case DELL_PRIVACY_TYPE_CAMERA: /* Camera mute */
> +		priv->last_status = status;
> +		sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> +		break;
> +	default:
> +			dev_dbg(&priv->wdev->dev, "unknown event type 0x%04x 0x%04x",
> +					type, code);
> +	}

Is this switch needed at all?


> +error:
> +	mutex_unlock(&list_mutex);
> +}
> +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 sprintf(buf, "%d\n", priv->features_present);

Please use `sysfs_emit()`. And I believe printing with %x would be preferable.


> +}
> +
> +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 sprintf(buf, "%d\n", priv->last_status);

Same here.


> +}
> +
> +static DEVICE_ATTR_RO(devices_supported);
> +static DEVICE_ATTR_RO(current_state);
> +
> +static struct attribute *platform_attributes[] = {

Maybe "privacy_attributes" or something similar would be more expressive?


> +	&dev_attr_devices_supported.attr,
> +	&dev_attr_current_state.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group privacy_attribute_group = {
> +	.attrs = platform_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 = NULL;

As far as I see there is not need to initialize `obj_present`.


> +	u32 *buffer;
> +	int ret = 0;
> +
> +	if (priv == NULL) {

Maybe `if (WARN_ON(!priv))`? But `!priv` is preferred in any case.


> +		pr_err("dell privacy priv is NULL\n");
> +		return -EINVAL;
> +	}
> +	/* check privacy support features and device states */
> +	obj_present = wmidev_block_query(wdev, 0);

`wmidev_block_query()` may return `NULL`, so you should check for that as well.


> +	if (obj_present->type != ACPI_TYPE_BUFFER) {
> +		dev_err(&wdev->dev, "Dell privacy failed to get device status!\n");

I think a more specific error message ("unexpected type") would be preferable.


> +		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 = -ENODEV;

I personally don't think ENODEV is the most suitable error code here. EINVAL/EILSEQ
seem more appropriate to me.


> +		privacy_valid = ret;
> +		goto obj_free;
> +	}
> +	buffer = (u32 *)obj_present->buffer.pointer;
> +	priv->features_present = buffer[0];
> +	priv->last_status = buffer[1];

I believe `get_unaligned_{le,be}32()` from `asm/unaligned.h` would be preferable
here.


> +	privacy_valid = 0;
> +
> +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, pos = 0;

There is actually no need for the `pos` variable.


> +
> +	priv = devm_kzalloc(&wdev->dev, sizeof(struct privacy_wmi_data),

Please use `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) +
> +			1,

I don't think that `+ 1` is not needed since the KE_END entry is already in the array.


> +			sizeof(struct key_entry), GFP_KERNEL);
> +	if (!keymap) {
> +		ret = -ENOMEM;
> +		goto err_free_dev;
> +	}
> +	/* 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[pos] = dell_wmi_keymap_type_0012[i];
> +		keymap[pos].code |= (0x0012 << 16);
> +		pos++;
> +	}
> +	ret = sparse_keymap_setup(priv->input_dev, keymap, NULL);
> +	if (ret)
> +		return ret;

A copy of the keymap is created by `sparse_keymap_setup()`, so returning
here will leak `keymap`. You could just call `kfree(keymap)` directly after
the `sparse_keymap_setup()` call. But I find it completely unnecessary
to do this allocate-copy-modify thing. Is there any reason why the static array
(`dell_wmi_keymap_type_0012`) cannot already contain the correct values?


> +	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");
> +		goto err_free_keymap;
> +	}
> +	mutex_lock(&list_mutex);
> +	list_add_tail(&priv->list, &wmi_list);
> +	mutex_unlock(&list_mutex);
> +	if (get_current_status(priv->wdev))
> +		goto err_free_keymap;

The input device is not unregistered in this branch.


> +	ret = sysfs_create_group(&wdev->dev.kobj, &privacy_attribute_group);

I suggest you replace `sysfs_{create,remove}_group()` with
`device_{add,remove}_group()` as it is more expressive in my opinion.


> +	if (ret)
> +		goto err_free_keymap;

Similarly, the input device is not unregistered in this branch.


> +	return 0;

`keymap` is again leaked by this return.


> +
> +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;
> +	sysfs_remove_group(&wdev->dev.kobj, &privacy_attribute_group);
> +

The input device is not unregistered.

> +	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)
> +		return -ENODEV;

The init function of a module that exports symbols must not fail, otherwise
it'll prevent the loading of dependent modules.


> +
> +	ret = dell_privacy_acpi_init();
> +	if (ret) {
> +		pr_err("failed to initialize privacy acpi driver: %d\n", ret);
> +		goto err_init;
> +	}
> +
> +	ret = wmi_driver_register(&dell_privacy_wmi_driver);
> +	if (ret) {
> +		pr_err("failed to initialize privacy wmi driver: %d\n", ret);
> +		return ret;
> +	}
> +	return 0;
> +
> +err_init:
> +	wmi_driver_unregister(&dell_privacy_wmi_driver);

At this point the WMI driver is not registered.


> +	return ret;
> +}
> +
> +static void dell_privacy_wmi_exit(void)

I believe this function could be marked __exit as well.


> +{
> +	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);
> +
> +MODULE_DEVICE_TABLE(wmi, dell_wmi_privacy_wmi_id_table);
> +MODULE_AUTHOR("Perry Yuan <perry_yuan@...l.com>");
> +MODULE_DESCRIPTION("Dell Privacy WMI Driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/platform/x86/dell-privacy-wmi.h b/drivers/platform/x86/dell-privacy-wmi.h
> new file mode 100644
> index 000000000000..9fa01d084f7d
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-wmi.h
> @@ -0,0 +1,33 @@
> +/* 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)
> +int  dell_privacy_valid(void);
> +void dell_privacy_process_event(int type, int code, int status);
> +#else /* CONFIG_DELL_PRIVACY */
> +static inline int dell_privacy_valid(void)
> +{
> +	return  -ENODEV;
> +}
> +
> +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,
> +};
> +#endif
> diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
> index bbdb3e860892..4b22bd21fc42 100644
> --- a/drivers/platform/x86/dell-wmi.c
> +++ b/drivers/platform/x86/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@...hat.com>");
>  MODULE_AUTHOR("Pali Rohár <pali@...nel.org>");
> @@ -381,6 +382,7 @@ static void dell_wmi_notify(struct wmi_device *wdev,
>  	u16 *buffer_entry, *buffer_end;
>  	acpi_size buffer_size;
>  	int len, i;
> +	int err;
>
>  	if (obj->type != ACPI_TYPE_BUFFER) {
>  		pr_warn("bad response type %x\n", obj->type);
> @@ -427,18 +429,30 @@ 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]);
> -			/* Extended data is currently ignored */
> -			break;
>  		case 0x0010: /* Sequence of keys pressed */
>  		case 0x0011: /* Sequence of events occurred */
>  			for (i = 2; i < len; ++i)
>  				dell_wmi_process_key(wdev, buffer_entry[1],
>  						     buffer_entry[i]);
>  			break;
> +		case 0x0012:

The comment "Event with extended data occurred" has been deleted.


> +#if IS_ENABLED(CONFIG_DELL_PRIVACY)
> +			err = dell_privacy_valid();
> +			if (err == 0) {
> +				dell_privacy_process_event(buffer_entry[1],
> +						buffer_entry[3], buffer_entry[4]);

What if `len < 5`?


> +			} else {
> +				if (len > 2)
> +					dell_wmi_process_key(wdev, buffer_entry[1],
> +							buffer_entry[2]);
> +			}
> +#else
> +			/* Extended data is currently ignored */
> +			if (len > 2)
> +				dell_wmi_process_key(wdev, buffer_entry[1],
> +						buffer_entry[2]);
> +#endif
> +			break;
>  		default: /* Unknown event */
>  			pr_info("Unknown WMI event type 0x%x\n",
>  				(int)buffer_entry[1]);
> --
> 2.25.1


Regards,
Barnabás Pőcze

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