[PATCH v3 2/9] platform/x86: dell-privacy: Use new buffer-based WMI API

Armin Wolf
2026-03-14T17:53:26Z

Use the new buffer-based WMI API to also support ACPI firmware
implementations that do not use ACPI buffers for the device state.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
drivers/platform/x86/dell/dell-wmi-privacy.c | 78 ++++++++++----------
1 file changed, 38 insertions(+), 40 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-privacy.c b/drivers/platform/x86/dell/dell-wmi-privacy.c
index ed099a431ea4..470273cc2fd2 100644
--- a/drivers/platform/x86/dell/dell-wmi-privacy.c
+++ b/drivers/platform/x86/dell/dell-wmi-privacy.c
@@ -9,6 +9,7 @@

#include <linux/acpi.h>
#include <linux/bitops.h>
+#include <linux/compiler_attributes.h>
#include <linux/input.h>
#include <linux/input/sparse-keymap.h>
#include <linux/list.h>
@@ -25,6 +26,26 @@
#define DELL_PRIVACY_CAMERA_EVENT 0x2
#define led_to_priv(c) container_of(c, struct privacy_wmi_data, cdev)

+/*
+ * 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
+ * };
+ */
+struct device_state {
+ __le32 devices_supported;
+ __le32 current_state;
+} __packed;
+
/*
* The wmi_list is used to store the privacy_priv struct with mutex protecting
*/
@@ -185,59 +206,36 @@ static struct attribute *privacy_attrs[] = {
};
ATTRIBUTE_GROUPS(privacy);

-/*
- * 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;
+ struct device_state *state;
+ struct wmi_buffer buffer;
+ int ret;

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;
- }
+ ret = wmidev_query_block(wdev, 0, &buffer);
+ if (ret < 0)
+ return ret;

- 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);
+ if (buffer.length < sizeof(*state)) {
+ dev_err(&wdev->dev, "Dell privacy buffer contains not enough data (%zu)!\n",
+ buffer.length);
ret = -EINVAL;
- goto obj_free;
+ goto buffer_free;
}
- buffer = (u32 *)obj_present->buffer.pointer;
- priv->features_present = buffer[0];
- priv->last_status = buffer[1];

-obj_free:
- kfree(obj_present);
+ state = buffer.data;
+ priv->features_present = le32_to_cpu(state->devices_supported);
+ priv->last_status = le32_to_cpu(state->current_state);
+
+buffer_free:
+ kfree(buffer.data);
return ret;
}

--
2.39.5