Hi,

On 4/12/21 11:19 AM, Perry Yuan wrote:
> From: Perry Yuan <[email protected]>
> 
> 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 <[email protected]>
> ---
> v5 -> v6:
> * addressed feedback from Hans
> * addressed feedback from Pierre
> * optimize some debug format with dev_dbg()
> * 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

Thank you, almost there. A few small remarks inline.

> 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       |  23 +-
>  drivers/platform/x86/dell/dell-privacy-wmi.c  | 394 ++++++++++++++++++
>  drivers/platform/x86/dell/dell-privacy-wmi.h  |  23 +
>  drivers/platform/x86/dell/dell-wmi.c          |   8 +-
>  7 files changed, 511 insertions(+), 7 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:     "[email protected]>"
> +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:     "[email protected]>"
> +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..05d124442b25 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
> +     select DELL_WMI

DELL_WMI is not a helper library which can be selected, please use depends on 
here.

More in general I'm a bit worried about the dependencies being added to
dell-laptop.c and dell-wmi.c on the new dell-privacy-wmi.ko module.

What if e.g. dell-laptop.c gets builtin while dell-privacy-wmi.c is a module.

Then we have dell-laptop.c depending on the dell_privacy_present linker-symbol,
but that symbol is in a module, so the main vmlinuz binary will fail to link
due to that missing symbol.

To fix this you need to add:

        depends on DELL_PRIVACY || DELL_PRIVACY = n

To the Kconfig sections for both DELL_WMI and DELL_LAPTOP


> +     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..e7ffc0b81208 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;

There is a problem in the del-laptop.c code with the led_classdev
unregistering which is not introduced by this patch, but this patch is a good
opportunity to fix this.

The problem is that in the dell_init error-exit path as well as in
dell_exit led_classdev_unregister() gets called unconditionally,
while the registering has only happened under the following condition:

        if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
            dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {

So this means that the code may end up unregistering a never
registered led_classdev which is not good.

Since you are making the unregistering conditional in this patch,
it would be good to also fix this issue.

Please change:

static bool has_privacy;

To:

static bool micmute_led_registered;



>  
>  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 (dell_privacy_present())
> +                     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;
> +             }
>       }

And change this block to

        if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
            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;
        }

This also looks cleaner/nicer with one less indent level too :)


>  
>       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)

Change this to:

        if (micmute_led_registered)
> +             led_classdev_unregister(&micmute_led_cdev);

This way the if condition also is more logical / easier to see
why the if is there.

>  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)

And here too, change this to:

        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..4be7548d1a03
> --- /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;
> +}
> +EXPORT_SYMBOL_GPL(dell_privacy_present);

I thought that we had chaned this to dell_privacy_has_mic_mute ?

Returning:

        return priv && (priv->features_present & BIT(DELL_PRIVACY_TYPE_AUDIO));

?

What has happened to that change, please change that back, the only user of
dell_privacy_present() is dell-laptop.c and that wants to know if
dell-privacy.c will be handling the mute-led or not, so only checking
for dell-privacy presence is not enough.



> +
> +/*
> + * 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;
> +     char *s = buf;
> +
> +     privacy_list = priv->features_present;
> +     for (type = DELL_PRIVACY_TYPE_AUDIO; type < DELL_PRIVACY_TYPE_MAX; 
> type++) {
> +             if (privacy_list & BIT(type))
> +                     s += sprintf(s, "[%s] [supported]\n", 
> privacy_types[type]);
> +             else
> +                     s += sprintf(s, "[%s] [unsupported]\n", 
> privacy_types[type]);
> +     }
> +
> +     return (s - buf);
> +}

As mentioned before I think (not sure), please use sysfs_emit_at here, like 
this:

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;
}

This will ensure that we never overrun the size of the passed in buffer.



> +
> +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;
> +     char *s = buf;
> +
> +     for (type = DELL_PRIVACY_TYPE_AUDIO; type < DELL_PRIVACY_TYPE_MAX; 
> type++) {
> +             if (privacy_supported & BIT(type)) {
> +                     if (privacy_state & BIT(type))
> +                             s += sprintf(s, "[%s] [unmuted]\n", 
> privacy_types[type]);
> +                     else
> +                             s += sprintf(s, "[%s] [muted]\n", 
> privacy_types[type]);
> +             }
> +     }
> +
> +     return (s - buf);
> +}

And the same here.


> +
> +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;
> +
> +     ret = dell_privacy_leds_setup(&priv->wdev->dev);
> +     if (ret)
> +             return ret;

This should be conditional on the audio privacy feature being supported:

        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 <[email protected]>");
> +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..04c49d2fa924
> --- /dev/null
> +++ b/drivers/platform/x86/dell/dell-privacy-wmi.h
> @@ -0,0 +1,23 @@
> +/* 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)
> +{}

This is missing a return false; between the {}.

> +#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..228e85a427f5 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 <[email protected]>");
>  MODULE_AUTHOR("Pali Rohár <[email protected]>");
> @@ -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 +439,12 @@ 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]))
> +                             /* privacy hotkey handle */;

Please change this comment to:

                                /* 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]);
> 



Regards,

Hans

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