From patchwork Thu Nov 23 00:48:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Armin Wolf X-Patchwork-Id: 13465652 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmx.de header.i=w_armin@gmx.de header.b="NdJ4HKu/" Received: from mout.gmx.net (mout.gmx.net [212.227.17.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F9D1171F; Wed, 22 Nov 2023 16:49:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1700700531; x=1701305331; i=w_armin@gmx.de; bh=IpekB6HD5lK7F+Kd+JJ/yZUrtd4vGeb83HYctPW2R2A=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To: References; b=NdJ4HKu/4pf25CY2MZm6gSq/iAN3XQT6Z8G+8KOQAdRChXMM9vMexkHsZ16giomR u9TQxLoqSYXjUKbZdM/LJUig0e34CQP6G6D9HVbHsZY7tc2fUHxqChbqCwOV6oZK/ 3CVVYsMH3beNP8RlV0CbhTRVhmjoqUysmb1W+z4jQlH+gb2avSDziI9niVPQ8vAhR C5zjkfOcCNMRnUYlUayNW3p0a68DWdeYJxIdFuMS70VgTCfwXVBWfqnVCUm6ISbIs IBV/px230m+lF/5TPTe1KCjPhb68txNd7TysHG75PJClK8zlH2vocu9IzTM+5DFui pHiVE8NgYwEBY9h/CA== 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 (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MwQXN-1rMfpu0oSr-00sLCa; Thu, 23 Nov 2023 01:48:51 +0100 From: Armin Wolf To: pali@kernel.org Cc: jdelvare@suse.com, linux@roeck-us.net, hdegoede@redhat.com, markgross@kernel.org, ilpo.jarvinen@linux.intel.com, platform-driver-x86@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 8/9] hwmon: (dell-smm) Document the WMI SMM interface Date: Thu, 23 Nov 2023 01:48:19 +0100 Message-Id: <20231123004820.50635-9-W_Armin@gmx.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231123004820.50635-1-W_Armin@gmx.de> References: <20231123004820.50635-1-W_Armin@gmx.de> Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Provags-ID: V03:K1:jfeSQcpPOAV12U7567kj2GLK7TAcbn+LqR+47Zhm2vMDhL47PDT kH/3wLvLTHRuKXeW9AnRV7+T889shCc9R1mOwcP17d3PEstgxlLEtFv2A4dmAW/fTg8V48n a6laLjfk28PRBUdKv2ZmohZyVhUS0yZNTDkZScvM4XbGROwrY64KVhX7niMk2rznXyEy6Kl Iv4sFQ3caidVxOZgrE6SQ== UI-OutboundReport: notjunk:1;M01:P0:8JXhW/qO+Zs=;h+T4cUIgBQMOQdKZEU/teBj3t4n i7AQl3qZyclJo4S+GOIwYibtiZdooOORDmwWgbUXX9Mx27iuc50to6wffpCJSZviCvMjE0BPt YR4NkCbI6szgJgc5p89HcRVyM+eShAdI9J/cQcm6e8AToRkvdzxqvcJsBErpqbJfaSX8/kbGE StFPuQXDIf5yaclpnbrFGK8lNrPX6iTKgpaNRSLLJfIniI+Z/7XLT4lh6UDi7My+xSQFE2hXs T+BT4REcOn5vuyhe2tk78hEtGKIdaWsh8pjrXjFfm/dTJSz+8pEwRunbFqTllfl7t8vPXjBkc zUOFS0jM7dSVI5C/sg9+RI6udbe3vDt+kv5w6Lk1EKXybghY2TBReHqxtRhWgeVOkh8uQfeCk skigdNF26DvAHS5UDj/pxcQJmF/dRXQYeWJjtA0kCarYsmqnl2pm8gLEjjj7wrYQkU0vt0/MU nL1wkqXO72ZDtz8v9Pcdr6Su0WSDCGADOWUYULuOZFaNeCfRCiuCl1fk0RozeKCdTd0E3DTCE RdA89SnXNAVaN0PVMiXzRIXqaMZUBau/ONxEEQ3cBoHDjqQL/N0ypYcuq140DNh2EXcCvpITB kGMDOJkF6PWvE9EqyIMhXRs+DTNmMJF7IcR/a/Xp6czr0XMvpGTTKVs/aVL692C7mS0fu1TeC d57+HARJOEvXr4p7fVUtGtQIH8GoXnvHj1aLsyrtWIT82kJxqi2NvPdEuP729QRXn1g+aUxF4 m4qT8H7mPgmLYsgiwAGurL2LAD/KiUtdba1K9wHZ4p/qu33wiReUBEjz69Jsv+DhLHqEpRifu f3AohTK+0RN7lIfjIFNY6jvN8zrLc6dXDtepZqQ5Rf0/sSfiAZSOWL6KvBEW8d3TWpyrDKOJc usV0DFgtzutjNz7FZsSwqA5IgnJV+ke370JTrGls6z/UhOV4ZjOvZgsGcCmb9R6uVK1Ye9Nvo 3im6R+Q1GYDYuQC6dLw9f9jOO7U= Document the WMI SMM interface so that future developers can better understand how it works. Reviewed-by: Hans de Goede Signed-off-by: Armin Wolf --- Documentation/hwmon/dell-smm-hwmon.rst | 38 ++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 3 deletions(-) -- 2.39.2 diff --git a/Documentation/hwmon/dell-smm-hwmon.rst b/Documentation/hwmon/dell-smm-hwmon.rst index d8f1d6859b96..977263cb57a8 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 +209,40 @@ 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 -----------------