Re: [PATCH] platform/x86: asus-wmi: add keystone dongle support

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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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 supported
> > 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).
> Thanks for this!
> 
> 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@linux.dev>
> > Signed-off-by: Dariusz Figzał <dariuszfigzal@gmail.com>
> > ---
> >  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.

> > +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
> 

-- 
 i.