On Tue, 26 May 2026, Vishnu Sankar wrote: > Hi Ilpo, > > Thank you for the comments. > > On Tue, May 26, 2026 at 2:19 AM Ilpo Järvinen > wrote: > > > > On Fri, 22 May 2026, Vishnu Sankar wrote: > > > > > Newer ThinkPad systems expose a USB-C Security (Restricted Mode) feature. > > > When active, USB-C data connections are disabled while power delivery is > > > preserved. This is useful for kiosk and physically-secured deployments. > > > > > > Hardware interface: > > > > > > The HKEY device exposes a read-only ACPI method USCS(): > > > > > > Return value bit layout: > > > Bit 16 : Capability flag (1 = feature present on this SKU) > > > Bit 0 : Current state (0 = security OFF, 1 = security ON) > > > > > > The sysfs attribute is read-only. > > > > > > The Fn+U followed by Fn+S hotkey chord is the only way to toggle the > > > hardware state. > > > > > > Hotkey: > > > > > > Fn+U followed by Fn+S generates HKEY event 0x131e. > > > > > > sysfs interface: > > > > > > /sys/devices/platform/thinkpad_acpi/usb_c_security (read-only) > > > "enabled\n" -- data connections are currently blocked > > > "disabled\n" -- data connections are currently allowed > > > > > > The attribute is hidden on SKUs where the USCS capability bit (bit 16) > > > is not set, so there is no ABI impact on unsupported hardware. > > > > > > Suggested-by: Mark Pearson > > > Signed-off-by: Vishnu Sankar > > > --- > > > .../admin-guide/laptops/thinkpad-acpi.rst | 24 ++++ > > > drivers/platform/x86/lenovo/thinkpad_acpi.c | 115 ++++++++++++++++++ > > > 2 files changed, 139 insertions(+) > > > > > > diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst > > > index f874db31801d..db4588af0278 100644 > > > --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst > > > +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst > > > @@ -1543,6 +1543,30 @@ Values: > > > > > > This setting can also be toggled via the Fn+doubletap hotkey. > > > > > > +USB-C Security > > > +-------------- > > > + > > > +sysfs: usb_c_security > > > + > > > +Reports the current state of the USB-C Security (Restricted Mode) feature > > > +on supported ThinkPad systems. When enabled, USB-C data connections are > > > +disabled while power delivery is preserved. > > > + > > > +The available command is:: > > > + > > > + cat /sys/devices/platform/thinkpad_acpi/usb_c_security > > > + > > > +Values: > > > + > > > + * ``enabled`` - USB-C data connections are currently blocked > > > + * ``disabled`` - USB-C data connections are currently allowed > > > + > > > +The attribute is read-only. The USB-C Security state can only be toggled > > > +via the Fn+U followed by Fn+S hotkey chord. > > > + > > > +The sysfs attribute is not created on platforms that do not support this > > > +feature. > > > + > > > Auxmac > > > ------ > > > > > > diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c > > > index e1cee42a1683..889db802185a 100644 > > > --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c > > > +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c > > > @@ -185,6 +185,7 @@ enum tpacpi_hkey_event_t { > > > TP_HKEY_EV_AMT_TOGGLE = 0x131a, /* Toggle AMT on/off */ > > > TP_HKEY_EV_CAMERASHUTTER_TOGGLE = 0x131b, /* Toggle Camera Shutter */ > > > TP_HKEY_EV_DOUBLETAP_TOGGLE = 0x131c, /* Toggle trackpoint doubletap on/off */ > > > + TP_HKEY_EV_USB_C_SECURITY = 0x131e, /* Toggle USB C Security ON/OFF */ > > > TP_HKEY_EV_PROFILE_TOGGLE = 0x131f, /* Toggle platform profile in 2024 systems */ > > > TP_HKEY_EV_PROFILE_TOGGLE2 = 0x1401, /* Toggle platform profile in 2025 + systems */ > > > > > > @@ -373,6 +374,8 @@ static struct { > > > u32 has_adaptive_kbd:1; > > > u32 kbd_lang:1; > > > u32 trackpoint_doubletap_enable:1; > > > + u32 usbc_security_supported:1; > > > + u32 usbc_security_enabled:1; > > > struct quirk_entry *quirks; > > > } tp_features; > > > > > > @@ -11265,6 +11268,111 @@ static struct ibm_struct hwdd_driver_data = { > > > .name = "hwdd", > > > }; > > > > > > +/************************************************************************* > > > + * USB-C Security subdriver > > > + * > > > + * HKEY.USCS(0) is a read-only ACPI method; its argument is ignored. > > > + * It always returns: > > > + * bit 16 - USB-C security capability present on this SKU or not > > > + * bit 0 - USB-C Security state (enable or disable) > > > + * > > > + * Hotkey > > > + * ------ > > > + * 0x131e (Fn+U, Fn+S): firmware toggles USBS before firing the event. > > > + * The driver reads back the new state and notifies the sysfs attribute. > > > + * > > > + */ > > > + > > > +/* USCS() return word bit layout */ > > > +#define USCS_CAP_BIT BIT(16) /* capability: feature present on SKU */ > > > +#define USCS_STATUS_BIT BIT(0) /* current security state */ > > > + > > > +static DEFINE_MUTEX(usbc_security_mutex); > > > + > > > +/* > > > + * usbc_security_query - read current USB-C security state via USCS() > > > + * @enabled: out - true when security is ON (data connections blocked) > > > + * > > > + * Returns true if the feature is supported and query succeeded, > > > + * false otherwise (feature absent or ACPI call failed). > > > + */ > > > +static bool usbc_security_query(bool *enabled) > > > +{ > > > + int status; > > > + > > > + mutex_lock(&usbc_security_mutex); > > > + if (!acpi_evalf(hkey_handle, &status, "USCS", "dd", 0)) { > > > + mutex_unlock(&usbc_security_mutex); > > > + return false; > > > + } > > > + mutex_unlock(&usbc_security_mutex); > > > > Please use cleanup.h. > Will do. > Will replace the manual mutex_lock/unlock pattern with guard(mutex). > > > > > + > > > + if (!(status & USCS_CAP_BIT)) { > > > + pr_debug("USCS cap bit absent (raw=0x%x)\n", status); > > > + return false; > > > + } > > > + > > > + *enabled = !!(status & USCS_STATUS_BIT); > > > > No need to do !! when assigning to bool. > Agreed, will remove the !!. > > > > > + return true; > > > +} > > > + > > > +/* sysfs: /sys/devices/platform/thinkpad_acpi/usb_c_security ---------- */ > > > +static ssize_t usb_c_security_show(struct device *dev, > > > + struct device_attribute *attr, > > > + char *buf) > > > +{ > > > + return sysfs_emit(buf, "%s\n", > > > + tp_features.usbc_security_enabled ? "enabled" : "disabled"); > > > > Please use string_choices.h. > Will use str_enabled_disabled() which is already used in > thinkpad_acpi.c for similar pattern. > > > > > +} > > > + > > > +static DEVICE_ATTR_RO(usb_c_security); > > > + > > > +static struct attribute *usbc_security_attributes[] = { > > > + &dev_attr_usb_c_security.attr, > > > + NULL, > > > +}; > > > + > > > +static umode_t usbc_security_attr_is_visible(struct kobject *kobj, > > > + struct attribute *attr, int n) > > > +{ > > > + return tp_features.usbc_security_supported ? attr->mode : 0; > > > +} > > > + > > > +static const struct attribute_group usbc_security_attr_group = { > > > + .is_visible = usbc_security_attr_is_visible, > > > + .attrs = usbc_security_attributes, > > > +}; > > > + > > > +static int tpacpi_usbc_security_init(struct ibm_init_struct *iibm) > > > +{ > > > + bool enabled; > > > + > > > + tp_features.usbc_security_supported = > > > + usbc_security_query(&enabled); > > > > Fits to one line. > Acked. > > > > > + tp_features.usbc_security_enabled = enabled; > > > > I'm not sure I follow the logic here as you always seem set it enabled > > disregarding even support or not? > > > > And that hotkey enabling seems deadcode with it already enabled here. > > > > I feel like I must blind to something obvious but cannot just find > > what that would be. > I'm sorry, this is a bug. > I will change to the following: > tp_features.usbc_security_supported = usbc_security_query(&enabled); > if (tp_features.usbc_security_supported) > tp_features.usbc_security_enabled = enabled; > > The hotkey path is not dead code — it updates usbc_security_enabled > when the user presses Fn+U Fn+S, since the EC firmware toggles the > state and fires the event. The init only captures the state at boot; > subsequent toggles come through the hotkey. Sorry for the confusion in > the init code. Oh, I see now what I was missing and it's just as obvious I was I thinking... I, for some reason, read these as: tp_features.usbc_security_enabled = true; ...but you had = enabled there. I'm sorry about my confusion. I find the the way usbc_security_query() is architected a bit confusing though, it returns supported/not supported in return value and another boolean through the bool pointer. And that looks broken, if usbc_security_query() returns early, it won't set *enabled which then remains uninitialized (contains pseudogarbage from stack so your testing might have been luck and had it always working the way you wanted). > > > + return 0; > > > +} > > > + > > > +/* tpacpi_usbc_security_hotkey - handle Fn+U Fn+S hotkey (0x131e) */ > > > +static bool tpacpi_usbc_security_hotkey(void) > > > +{ > > > + bool enabled; > > > + > > > + if (!tp_features.usbc_security_supported) > > > + return false; > > > + > > > + if (!usbc_security_query(&enabled)) > > > + return false; > > > + > > > + tp_features.usbc_security_enabled = enabled; > > > + sysfs_notify(&tpacpi_pdev->dev.kobj, NULL, "usb_c_security"); > > > + return true; > > > +} > > > + > > > +static struct ibm_struct usbc_security_driver_data = { > > > + .name = "usbc_security", > > > +}; > > > + > > > /* --------------------------------------------------------------------- */ > > > > > > static struct attribute *tpacpi_driver_attributes[] = { > > > @@ -11325,6 +11433,7 @@ static const struct attribute_group *tpacpi_groups[] = { > > > &dprc_attr_group, > > > &auxmac_attr_group, > > > &hwdd_attr_group, > > > + &usbc_security_attr_group, > > > NULL, > > > }; > > > > > > @@ -11479,6 +11588,8 @@ static bool tpacpi_driver_event(const unsigned int hkey_event) > > > case TP_HKEY_EV_PROFILE_TOGGLE2: > > > platform_profile_cycle(); > > > return true; > > > + case TP_HKEY_EV_USB_C_SECURITY: > > > + return tpacpi_usbc_security_hotkey(); > > > } > > > > > > return false; > > > @@ -11930,6 +12041,10 @@ static struct ibm_init_struct ibms_init[] __initdata = { > > > .init = tpacpi_hwdd_init, > > > .data = &hwdd_driver_data, > > > }, > > > + { > > > + .init = tpacpi_usbc_security_init, > > > + .data = &usbc_security_driver_data, > > > + }, > > > }; > > > > > > static int __init set_ibm_param(const char *val, const struct kernel_param *kp) > > > > > > > -- > > i. > > > > I will update the v2 with all these changes soon, if no further comments. > -- i.