From patchwork Fri Nov 3 18:57:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Armin Wolf X-Patchwork-Id: 13444916 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A1C3C4167D for ; Fri, 3 Nov 2023 18:58:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346225AbjKCS6W (ORCPT ); Fri, 3 Nov 2023 14:58:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345884AbjKCS6T (ORCPT ); Fri, 3 Nov 2023 14:58:19 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CC2AD6C; Fri, 3 Nov 2023 11:58:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1699037858; x=1699642658; i=w_armin@gmx.de; bh=TJgFoJSEZ7oco6vbH2uSKw0a8ZVpn5/M8nMVqzHvOZo=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To: References; b=BYSCoL+pIdDXwXl/6kR4OTi+DESwfNZOxbep/QZIKAFJKcUApLJltQGJZ2d4nYQe YEeVFpxauq/8XMMKZuKWWOAgC0TA+b5kgqFXZnYiPNawzau8js40HcnoexWWxY+De MO9OeKwO5k+K2G+FvEtzfZ9iBbEkMSiiaTEiXCRSX0N6Q0qt3iNddNkEsG0k7uFsM kLEX5z8M6DpVnDmUl26dLLOCqGnUZvAX/rhWzagTGIzzlVymQ9c6y8C9CyOntm0xU pxH2vCamA9Mz10IAqX2jGz+Q8Q6ExY7ZkRe5wMlG9qKUfCX6zZ/3+NUFquXvbvctL Ckq19/JQeUbMC7oALw== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from mx-amd-b650.users.agdsn.de ([141.30.226.129]) by mail.gmx.net (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MeCpR-1rXVAL0yIx-00bLtj; Fri, 03 Nov 2023 19:57:38 +0100 From: Armin Wolf To: pali@kernel.org Cc: jdelvare@suse.com, linux@roeck-us.net, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 8/9] hwmon: (dell-smm) Document the WMI SMM interface Date: Fri, 3 Nov 2023 19:57:15 +0100 Message-Id: <20231103185716.11007-9-W_Armin@gmx.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231103185716.11007-1-W_Armin@gmx.de> References: <20231103185716.11007-1-W_Armin@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:TrSHmD4i5OZnstY4A3RxAkbMGUr3UEZcJLJCOCdsFx5ENHUxOT2 jaYRNr0AaCuMvMeF5CTDfjR6P9wLtgtm8cPW8f769MmiY7vGZ838/POYuf0sa1tXFTTe28c lbgTHWPRvpUMpMYLNOuha8lxRGJACvFeEhFjpqf1f2GvquK41MLU6PKsaaRfDdmaO5dMaqr 34eY9Z+Lin9EH6pNPhBHA== UI-OutboundReport: notjunk:1;M01:P0:Rlimnw2H6FE=;af55sEDBauzCOwcmmik/s0KEY+n dpm/c5tj+HsULnAQAR89zPZ5YCPO8i8+iHVHtf/P7fLFa/IznTitSGa31xr7uhSPbkkquJTF9 AvPQk0GBP/bSKj5gkUv5XYanRYz+shOYwBk1CNz29Rfzy2uEKKuC2TUJTBa86BYiBPnU1Me3h teX5C00T7VpxkFEYjKJuRf7SUedNSbjSvTvPQsoRSE+MZR/+9RMq6lMANVSRgEdViV9qHIMB0 KopR1oDEqiI/XY6r9SXzYxIMHzgCU4Z8txvTZ3ugX1MqfrYL+NAbcKyrrbEJLgAIU5VXCubKn Cm0Gd2hEplcQrMrBhfkQCjk/8NhVVhp7BDM6P/HfZ6B4frbHdfjGPhHHfrB6efDlQwRNgEoUI w+cz4mYwq9Y3y2ggKLZL0aLarr62ePUvQBOw3dA8mFNqwkPmACGluFigVW1xcY8ejE8Ln/B5s crujHHAl3k/uH8BWyMZwgv/HLZSlir3gRkI+I4m3uCwb+gFP4xfmtuYGWMxJfHHOBkixnljJY DdfoeYNNtuwb4WeuUODCaWgKSF5EjedEAna7uM+QmiUF7S7hpPkqwrjebcLJIa1CzmY0nVK2L YYGU4z9/jXXY9PPHIdJgWCgthRIJ1IB8gjbOgz6Kt0+enPcViSSjlmVBNi5ztqcCdfo2c9n4N KzQMWXg10KkcJSXZ1RE807LlYOzvVtO//VFnEK2Am1apimECgioAigk4AsZtqImW8TaDoodbv xeAWHVqYNxVb/kGxtSkjVwhS9DqKKKVNljq96ehuH0UUFtyJhAJYXM/tgxRD1/TmsW1+5O8hi IsnYX4jNS1fK++m4PGAhgGjsVneV+4mdV2k/S+1wbBadDQZQYffS7TJS+5Kc8ZZWNZ1M0I1q+ nRApftoAAUoyr/xxhDQ+GsyBP0Doim4Nj7vMifLVX6uNfCyLGrlEFPOoXHqBm7FsGSoudXFwD 37Fmb/eqPPWOAPxlE/8q/L7yUc4= Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org Document the WMI SMM interface so that future developers can better understand how it works. Signed-off-by: Armin Wolf --- Documentation/hwmon/dell-smm-hwmon.rst | 33 +++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) -- 2.39.2 diff --git a/Documentation/hwmon/dell-smm-hwmon.rst b/Documentation/hwmon/dell-smm-hwmon.rst index d8f1d6859b96..fea8cf76088e 100644 --- a/Documentation/hwmon/dell-smm-hwmon.rst +++ b/Documentation/hwmon/dell-smm-hwmon.rst @@ -186,8 +186,7 @@ SMM Interface The driver uses the SMM interface to send commands to the system BIOS. This interface is normally used by Dell's 32-bit diagnostic program or on newer notebook models by the buildin BIOS diagnostics. -The SMM is triggered by writing to the special ioports ``0xb2`` and ``0x84``, -and may cause short hangs when the BIOS code is taking too long to +The SMM may cause short hangs when the BIOS code is taking too long to execute. The SMM handler inside the system BIOS looks at the contents of the @@ -210,7 +209,35 @@ The SMM handler can signal a failure by either: - setting the lower sixteen bits of ``eax`` to ``0xffff`` - not modifying ``eax`` at all -- setting the carry flag +- setting the carry flag (legacy SMM interface only) + +Legacy SMM Interface +-------------------- + +When using the legacy SMM interface, a SMM is triggered by writing the least significant byte +of the command code to the special ioports ``0xb2`` and ``0x84``. This interface is not +described inside the ACPI tables and can thus only be detected by issuing a test SMM call. + +WMI SMM Interface +----------------- + +On modern Dell machines, the SMM calls are done over ACPI WMI: + +:: + + #pragma namespace("\\\\.\\root\\dcim\\sysman\\diagnostics") + [WMI, Provider("Provider_DiagnosticsServices"), Dynamic, Locale("MS\\0x409"), Description("RunDellDiag"), guid("{F1DDEE52-063C-4784-A11E-8A06684B9B01}")] + class LegacyDiags { + [key, read] string InstanceName; + [read] boolean Active; + + [WmiMethodId(1), Implemented, read, write, Description("Legacy Method ")] void Execute([in, out] uint32 EaxLen, [in, out, WmiSizeIs("EaxLen") : ToInstance] uint8 EaxVal[], [in, out] uint32 EbxLen, [in, out, WmiSizeIs("EbxLen") : ToInstance] uint8 EbxVal[], [in, out] uint32 EcxLen, [in, out, WmiSizeIs("EcxLen") : ToInstance] uint8 EcxVal[], [in, out] uint32 EdxLen, [in, out, WmiSizeIs("EdxLen") : ToInstance] uint8 EdxVal[]); + }; + +Some machines support only the WMI SMM interface, while some machines support both interfaces. +The driver automatically detects which interfaces are present and will use the WMI SMM interface +if the legacy SMM interface is not present. The WMI SMM interface is usually slower than the +legacy SMM interface since ACPI methods need to be called in order to trigger a SMM. SMM command codes -----------------