Re: [PATCH] platform/x86: asus-wmi: add keystone dongle support
From: Dariusz Figzał
Date: Thu May 28 2026 - 07:08:05 EST
On 5/28/26 11:06 AM, Ilpo Järvinen wrote:
On Thu, 28 May 2026, Denis Benato wrote:
On 5/26/26 23:44, Dariusz Figzał wrote:
The ASUS Keystone is a physical NFC-like dongle that slots into supportedThanks for this!
ASUS laptops. The EC fires WMI notify code 0xB4 on insert/remove events.
Expose the current insert state via a sysfs attribute by querying WMI
device ID 0x00120091 (DSTS). This devid does not follow the standard DSTS
convention: PRESENCE_BIT (0x00010000) encodes the insert state rather than
feature presence, and STATUS_BIT is never set. Presence of a keystone slot
is detected by a successful DSTS call (any result other than -ENODEV).
Ilpo might have some suggestions on how to make the code better,
As we discussed a fair bit about this I say LGTM.
Reviewed-by: Denis Benato <denis.benato@xxxxxxxxx>
Signed-off-by: Dariusz Figzał <dariuszfigzal@xxxxxxxxx>
---
drivers/platform/x86/asus-wmi.c | 75 ++++++++++++++++++++++
include/linux/platform_data/x86/asus-wmi.h | 7 ++
2 files changed, 82 insertions(+)
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 80144c412b90..a3fa3921aef3 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -70,6 +70,7 @@ module_param(fnlock_default, bool, 0444);
#define NOTIFY_KBD_TTP 0xae
#define NOTIFY_LID_FLIP 0xfa
#define NOTIFY_LID_FLIP_ROG 0xbd
+#define NOTIFY_KEYSTONE 0xb4
#define ASUS_WMI_FNLOCK_BIOS_DISABLED BIT(0)
@@ -279,6 +280,8 @@ struct asus_wmi {
u32 tablet_switch_dev_id;
bool tablet_switch_inverted;
+ bool keystone_detected;
+
enum fan_type fan_type;
enum fan_type gpu_fan_type;
enum fan_type mid_fan_type;
@@ -646,6 +649,66 @@ static bool asus_wmi_dev_is_present(struct asus_wmi *asus, u32 dev_id)
return status == 0 && (retval & ASUS_WMI_DSTS_PRESENCE_BIT);
}
+/* Keystone *******************************************************************/
+
+static ssize_t keystone_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct asus_wmi *asus = dev_get_drvdata(dev);
+ u32 retval;
+ int err;
+
+ err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_KEYSTONE, &retval);
+ if (err)
+ return err;
+
+ return sysfs_emit(buf, "%d\n", !!(retval & ASUS_WMI_DSTS_PRESENCE_BIT));
+}
+
+static DEVICE_ATTR_RO(keystone);
+
+static void asus_wmi_keystone_notify(struct asus_wmi *asus)
+{
+ sysfs_notify(&asus->platform_device->dev.kobj, NULL, "keystone");
+}
+
+static int asus_wmi_keystone_init(struct asus_wmi *asus)
+{
+ u32 retval;
+ int err;
+
+ /*
+ * Use a raw devstate call rather than asus_wmi_dev_is_present().
+ * For this devid, PRESENCE_BIT encodes current insert state, not
+ * feature presence, so asus_wmi_dev_is_present() would return false
+ * whenever the dongle is absent at boot, even on machines that have
+ * a keystone slot.
+ * -ENODEV means the firmware doesn't know this devid at all.
+ * retval is not examined here, only the return code matters.
+ */
+ err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_KEYSTONE, &retval);
+ if (err == -ENODEV)
+ return 0;
+ if (err)
+ return err;
+
+ err = device_create_file(&asus->platform_device->dev, &dev_attr_keystone);
+ if (err)
+ return err;
+
+ asus->keystone_detected = true;
+ return 0;
+}
The visibility of this should be controlled using .is_visible and the
attribute should be placed into the normal attribute array.
Thanks for the review. I'll fix this in v2.
+static void asus_wmi_keystone_exit(struct asus_wmi *asus)
+{
+ if (!asus->keystone_detected)
+ return;
+
+ device_remove_file(&asus->platform_device->dev, &dev_attr_keystone);
+ asus->keystone_detected = false;
+}
+
/* Input **********************************************************************/
static void asus_wmi_tablet_sw_report(struct asus_wmi *asus, bool value)
{
@@ -4575,6 +4638,12 @@ static void asus_wmi_handle_event_code(int code, struct asus_wmi *asus)
return;
}
+ if (code == NOTIFY_KEYSTONE) {
+ if (asus->keystone_detected)
+ asus_wmi_keystone_notify(asus);
+ return;
+ }
+
if (code == NOTIFY_KBD_FBM || code == NOTIFY_KBD_TTP) {
if (asus->fan_boost_mode_available)
fan_boost_mode_switch_next(asus);
@@ -5085,6 +5154,10 @@ static int asus_wmi_add(struct platform_device *pdev)
if (err)
goto fail_sysfs;
+ err = asus_wmi_keystone_init(asus);
+ if (err)
+ dev_warn(&pdev->dev, "Keystone initialization failed: %d\n", err);
+
err = asus_wmi_input_init(asus);
if (err)
goto fail_input;
@@ -5170,6 +5243,7 @@ static int asus_wmi_add(struct platform_device *pdev)
fail_hwmon:
asus_wmi_input_exit(asus);
fail_input:
+ asus_wmi_keystone_exit(asus);
asus_wmi_sysfs_exit(asus->platform_device);
fail_sysfs:
fail_custom_fan_curve:
@@ -5191,6 +5265,7 @@ static void asus_wmi_remove(struct platform_device *device)
asus_wmi_backlight_exit(asus);
asus_screenpad_exit(asus);
asus_wmi_input_exit(asus);
+ asus_wmi_keystone_exit(asus);
asus_wmi_led_exit(asus);
asus_wmi_rfkill_exit(asus);
asus_wmi_debugfs_exit(asus);
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index 554f41b827e1..c29962d5baac 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -147,6 +147,13 @@
#define ASUS_WMI_DEVID_GPU_MUX 0x00090016
#define ASUS_WMI_DEVID_GPU_MUX_VIVO 0x00090026
+/* Keystone dongle insert/remove state.
+ * PRESENCE_BIT (0x00010000) encodes insert state:
+ * 0x00010000 = inserted, 0x00000000 = absent. STATUS_BIT is never set.
+ * 0xFFFFFFFE means no keystone slot on this machine.
+ */
+#define ASUS_WMI_DEVID_KEYSTONE 0x00120091
+
/* TUF laptop RGB modes/colours */
#define ASUS_WMI_DEVID_TUF_RGB_MODE 0x00100056
#define ASUS_WMI_DEVID_TUF_RGB_MODE2 0x0010005A