From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30F4B41D4CE; Tue, 7 Jul 2026 13:32:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783431157; cv=none; b=t0rXO5UI+so6s7lr0Nt8SaqvqDiSlGxUbd3G1aU2jdvUcsiAU/wpy2CslGg/RRgYuP0u+Y4uU0kPrh59uc4kw9nXyWWv5dKM3xfKU8m9U1T8E03UNyk4x6Zv4I4rclFP/z3u8ZxlNxD4Bp4ootcEMywZsJd+Pe9krzue+uEisMQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783431157; c=relaxed/simple; bh=nvIOop0wkzf0lbjWCF3/zxj3ywTCvsCVOIEs1kM1fFM=; h=From:Date:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=Nso5oyxuBXQhT2a68y6+9eKnUYRwh8JgyDzhdEKTDeGE9eRqtWZDJ/wLbhkxBq8LF7Mtjun6neEHzqIzoLno4quxcl3ru02eS7/Eb4Q2Vxbl+HChywFvNUOV0uEVmSyHeW6st963jHvhHneIhf74c/EJuSrySlsnOVES3GZri/o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PdhuXOqs; arc=none smtp.client-ip=198.175.65.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PdhuXOqs" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1783431156; x=1814967156; h=from:date:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=nvIOop0wkzf0lbjWCF3/zxj3ywTCvsCVOIEs1kM1fFM=; b=PdhuXOqskDrNTYoQ8tMRUA/V844YKMxXZ1pQS+U3CuRqiWqNVoBEBcXB Hi9cpBHnNjTrLOLuY0izsumSzqfDLe+nnpmqy3jl6MvvffJGr/25+a6SY 4MIi14V2oZKgZ2DLBbVws3MC4KJgkCdaL/cJyyj3lTjSbzjUt+XnuFCtt 0hj9PvqSXeFCL/pYsz2pFzJF/9Tt7UVfTw+L1WbZuMKoM5W12RQbpb5/R uEdCVQYOpFaeOnXk1j6mD2rWIFq+ahpB1mN/y0qp1lVBDBdtAKzZTueec D8oD8OsEbcQCgq2+ozKS+kGeNRxeFzynDoOcm1AOC3HbF37EhsFyM8VYB Q==; X-CSE-ConnectionGUID: eyL7N0skRuCccIyzTvOwaA== X-CSE-MsgGUID: 9tcXnjdbRoe0ZkcuPtrEFA== X-IronPort-AV: E=McAfee;i="6800,10657,11840"; a="84267097" X-IronPort-AV: E=Sophos;i="6.25,153,1779174000"; d="scan'208";a="84267097" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2026 06:32:36 -0700 X-CSE-ConnectionGUID: AvFGhoisQ06gXwv+p7NYfQ== X-CSE-MsgGUID: T69eIJ1HTJKL28VAlr6/Yw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,153,1779174000"; d="scan'208";a="277220107" Received: from ijarvine-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.226]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2026 06:32:31 -0700 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Tue, 7 Jul 2026 16:32:28 +0300 (EEST) To: Vishnu Sankar cc: Mark Pearson , skhan@linuxfoundation.org, corbet@lwn.net, hmh@hmh.eng.br, Hans de Goede , derekjohn.clark@gmail.com, LKML , ibm-acpi-devel@lists.sourceforge.net, linux-doc@vger.kernel.org, platform-driver-x86@vger.kernel.org, vsankar@lenovo.com Subject: Re: [PATCH v3] platform/x86: thinkpad_acpi: Add USB-C Security (USCS) support In-Reply-To: <20260613225736.30906-1-vishnuocv@gmail.com> Message-ID: <2c7578ec-432e-e77c-c19f-668e2edc1733@linux.intel.com> References: <20260613225736.30906-1-vishnuocv@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Sun, 14 Jun 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 > --- > Changes since v2: > - Move usbc_security_enabled out of tp_features bitfield to a bool > member of tp_features to avoid unsafe concurrent bitfield RMW; > usbc_security_supported remains a bitfield as it is init-only. > - Pass &tp_features.usbc_security_enabled directly to > usbc_security_query() removing the local bool intermediary > in both init and hotkey paths. > - Remove extra blank line before */ in block comment. > - Fix kerneldoc Returns: syntax and rewrite return value description > to match the int return type. > - Split ternary return into two separate if statements for clarity > > Changes since v1: > - Use guard(mutex) from cleanup.h instead of manual mutex_lock/unlock > - Revert usbc_security_query() to return int (-EIO/-ENODEV/0) instead > of bool to avoid uninitialized *enabled bug on unsupported platforms > - Remove !! when assigning to bool in usbc_security_query() > - Remove dead tp_features.usbc_security_supported check in show() > since is_visible() already gates the attribute on unsupported SKUs > - Use str_enabled_disabled() from string_choices.h in show() > - Fix uninitialized *enabled bug in tpacpi_usbc_security_init() by > only assigning usbc_security_enabled after a successful query > --- > .../admin-guide/laptops/thinkpad-acpi.rst | 24 ++++ > drivers/platform/x86/lenovo/thinkpad_acpi.c | 116 ++++++++++++++++++ > 2 files changed, 140 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..59b485a57ffe 100644 > --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c > +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c > @@ -38,6 +38,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -66,6 +67,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -185,6 +187,7 @@ 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, /* USB C Security (Fn+U, Fn+S) */ > 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 +376,8 @@ static struct { > u32 has_adaptive_kbd:1; > u32 kbd_lang:1; > u32 trackpoint_doubletap_enable:1; > + u32 usbc_security_supported:1; > + bool usbc_security_enabled; > struct quirk_entry *quirks; > } tp_features; > > @@ -11265,6 +11270,110 @@ 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); Please add a comment to document what the lock protects. > + > +/** > + * usbc_security_query - read current USB-C security state via USCS() > + * @enabled: out - true when security is ON (data connections blocked) > + * > + * Returns: > + * 0 success, @enabled contains the current state > + * -EIO ACPI evaluation failed > + * -ENODEV capability bit absent; feature not present on this SKU* > + */ > +static int usbc_security_query(bool *enabled) > +{ > + int status; > + > + guard(mutex)(&usbc_security_mutex); > + if (!acpi_evalf(hkey_handle, &status, "USCS", "dd", 0)) > + return -EIO; > + > + if (!(status & USCS_CAP_BIT)) { > + pr_debug("USCS cap bit absent (raw=0x%x)\n", status); > + return -ENODEV; > + } > + > + *enabled = status & USCS_STATUS_BIT; > + return 0; > +} > + > +/* 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", > + str_enabled_disabled(tp_features.usbc_security_enabled)); > +} > + > +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) > +{ > + int err; > + > + err = usbc_security_query(&tp_features.usbc_security_enabled); > + if (err == -ENODEV) > + return 0; > + if (err) > + return err; > + > + tp_features.usbc_security_supported = true; > + return 0; > +} > + > +/* tpacpi_usbc_security_hotkey - handle Fn+U Fn+S hotkey (0x131e) */ > +static bool tpacpi_usbc_security_hotkey(void) > +{ > + if (!tp_features.usbc_security_supported) > + return false; > + > + if (usbc_security_query(&tp_features.usbc_security_enabled)) > + return false; > + > + 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 +11434,7 @@ static const struct attribute_group *tpacpi_groups[] = { > &dprc_attr_group, > &auxmac_attr_group, > &hwdd_attr_group, > + &usbc_security_attr_group, > NULL, > }; > > @@ -11479,6 +11589,8 @@ 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 +12042,10 @@ 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.