From patchwork Sun Mar 3 08:49:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Shenhar, Talel" X-Patchwork-Id: 10837003 X-Patchwork-Delegate: eduardo.valentin@ti.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2595117EF for ; Sun, 3 Mar 2019 08:50:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FC472A478 for ; Sun, 3 Mar 2019 08:50:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 046B82A4DD; Sun, 3 Mar 2019 08:50:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 690A92A4D7 for ; Sun, 3 Mar 2019 08:50:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726066AbfCCIuZ (ORCPT ); Sun, 3 Mar 2019 03:50:25 -0500 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:59127 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725923AbfCCIuY (ORCPT ); Sun, 3 Mar 2019 03:50:24 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1551603023; x=1583139023; h=from:to:subject:date:message-id:in-reply-to:references: mime-version; bh=4S9FTXzHr+n2eJIbYY/rc6G5bREyIJD7sJxEazerOHM=; b=ijbdmLtmXbochNqBP/rrMaPdFkAGiinV6tjQz3BM8jnKRE9liD8QDjXj TizXrTPvuOakdMPPse4E66/EIEiaLjTk3P+JEHpV/7qe4edPR55SFeOAX saPmzMvGzU/2RSFUStuvhIjd4shxdNz9oM3E4qDZr+wtYf0bbx/EyMVaq U=; X-IronPort-AV: E=Sophos;i="5.58,435,1544486400"; d="scan'208";a="662822105" Received: from sea3-co-svc-lb6-vlan3.sea.amazon.com (HELO email-inbound-relay-1e-17c49630.us-east-1.amazon.com) ([10.47.22.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 03 Mar 2019 08:50:20 +0000 Received: from EX13MTAUEA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1e-17c49630.us-east-1.amazon.com (8.14.7/8.14.7) with ESMTP id x238oGSb086937 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Sun, 3 Mar 2019 08:50:17 GMT Received: from EX13D01EUB001.ant.amazon.com (10.43.166.194) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Sun, 3 Mar 2019 08:50:16 +0000 Received: from udc4a3e82dbc15a031435.hfa14.amazon.com (10.43.161.217) by EX13D01EUB001.ant.amazon.com (10.43.166.194) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Sun, 3 Mar 2019 08:50:10 +0000 From: Talel Shenhar To: , , , , , , , , , , , Subject: [PATCH 1/2] dt-bindings: thermal: thermal_mmio: Add binding documentation Date: Sun, 3 Mar 2019 10:49:25 +0200 Message-ID: <1551602966-2334-2-git-send-email-talel@amazon.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551602966-2334-1-git-send-email-talel@amazon.com> References: <1551602966-2334-1-git-send-email-talel@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.161.217] X-ClientProxiedBy: EX13D24UWA004.ant.amazon.com (10.43.160.233) To EX13D01EUB001.ant.amazon.com (10.43.166.194) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add thermal binding documentation for thermal MMIO driver. Signed-off-by: Talel Shenhar --- .../devicetree/bindings/thermal/thermal_mmio.txt | 173 +++++++++++++++++++++ 1 file changed, 173 insertions(+) create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt diff --git a/Documentation/devicetree/bindings/thermal/thermal_mmio.txt b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt new file mode 100644 index 0000000..1f4d738 --- /dev/null +++ b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt @@ -0,0 +1,173 @@ +Generic Thermal MMIO Driver + +The generic thermal driver enables easy connectivity between "simple" +thermal HW devices to the thermal subsystem. "simple" - thermal HW that +doesn't need any configuration (such as power reset or clock enable) by a +driver and only exports the temperature via simple MMIO access, or, +alternatively, all the configuration is done by other entity (e.g. +bootloader). + +Any system that allows temperature reading via a single memory map read, be +it register or shared memory, is a potential candidate to work with this +driver. +This driver allows manipulations on the read value in order to allow some +flexibility for the various thermal HW, e.g. sensor-factor which will be +multiplied by the read value. + +This driver is most suitable for cases such as the following: +- The entire thermal HW setup (e.g. configure the thermal HW to work in + continuous mode) is done by another SW entity (e.g. bootloader) and all + that is left is to read the current temperature from a register +- The thermal reading is done by an external CPU (e.g. micro-controller) + and that CPU is exporting the reading via a shared memory +- The thermal HW setup and reading is done via CPLD, which exports the + current temperature to the system via a register +- The thermal HW is working out-of-the-box and only reports temperature via + a single register access + +Some examples for cases that this driver is not suitable for: +- Your HW need clock enabling to be done by thermal driver +- Your HW need some registers configurations in order to start reporting + temperatures and it is not doable by other entities (e.g. bootloader) +- Your HW allows reading of temperatures only between ADCs (or any other + timing constrains) +- In case your HW was configured by a bootloader and it lose the + configuration as part of low-power-state and need to be reconfigured. + (bootloader configuration typically is not sustained across low power + states) +- In case the reading from the MMIO require any type of locking + +So the only operation this driver will do is MMIO read for the temperature. +In case you are using HW that require some configurations this driver is +not suitable (you can decide to move all the configuration logic into your +bootloader and only leave the temperature reading to this driver but this +is up to you). + +An example of a system that uses this driver is the Amazon Nitro SoC in +which there is the main CPU and micro-controller: +(1) The micro-controller accesses an SBUS controller to read the thermal + sensor from an SBUS slave called Avago Technologies digital + Temperature/Voltage Sensor (ip16_SENS_thermvolt25_0) +(2) Once the micro-controller gathers the temperature it relays it to the + main CPU via a Shared Integrated RAM which is MMIO accessible by the CPU +(3) The thermal_mmio driver that runs on the main CPU will read the + temperature via an MMIO access to the Shared RAM + ++------------------+ +----------------+ +| | (3) | | +| Main CPU +----->+ Integrated RAM | +| | | | ++------------------+ +---------^------+ + |(2) ++-----------------+ +------------------+ +| | (1) | | +| SBUS controller <-------+ micro-controller | +| | | | ++--------+--------+ +------------------+ + | ++--------v---------------------+ +| | +| Avago Technologies digital | +| Temperature/Voltage Sensor | +| (ip16_SENS_thermvolt25_0) | +| | ++------------------------------+ + +Required properties: +- compatible: "thermal-mmio". +- reg: The physical base address and length of the sensor's registers. +- #thermal-sensor-cells: Must be 1. See ./thermal.txt for a description. + +Optional properties: +- sensor-width: Width (in bytes) of each consecutive sensor. + Supported: 1, 2, 4. + (Default = 4) +- sensor-mask: Mask to be applied on the raw read value before any + calculation. + (Default = 0xFFFFFFFF) +- sensor-factor: Scale value by which to multiple the masked read value + This is a signed 32 bit value. + (Default = 1) +- sensor-bias: Bias value to be added to the scaled value. + This is a signed 32 bit value. + (Default = 0) +- sensor-divider: Dividing value by which to divide the calculated value. + Diving will be Integer Division. + This is a unsigned 32 bit value. + (Default = 1) + +Conversion formula from HW MMIO read value to millidegrees (Celsius): +T_millidegrees = (bias + (T_raw & mask)*factor)/divider + +Example 1, two thermal devices with one thermal sensor each, that uses only +the required properties (uses default): + + thermal_d1: thermal_d1 { + compatible = "thermal-mmio"; + reg = <0x0 0x05002860 0x0 0x4>; + #thermal-sensor-cells = <0x1>; + }; + + thermal_d2: thermal_d2 { + compatible = "thermal-mmio"; + reg = <0x0 0x05000730 0x0 0x4>; + #thermal-sensor-cells = <0x1>; + }; + + thermal-zones { + thermal_d1_z0 { + polling-delay-passive = <250>; + polling-delay = <1000>; + thermal-sensors = <&thermal_d1 0>; + trips { + thermal_d1_z0_crit { + temperature = <105000>; + hysteresis = <2000>; + type = "critical"; + }; + }; + + }; + + thermal_d2_z0 { + polling-delay-passive = <250>; + polling-delay = <1000>; + thermal-sensors = <&thermal_d2 0>; + trips { + thermal_d2_z0_crit { + temperature = <105000>; + hysteresis = <2000>; + type = "critical"; + }; + }; + }; + }; + +Example 2, one thermal device with two sensors of 6 bits each each, that +has a factor of -5, bias of 23 and dividing of 2: + + thermal_d3: thermal_d3 { + compatible = "thermal-mmio"; + reg = <0x0 0x05005700 0x0 0x2>; + #thermal-sensor-cells = <0x1>; + sensor-width = <1>; + sensor-mask = <0x3F>; + sensor-factor = <(-5)>; + sensor-bias = <23>; + sensor-divider = <2>; + }; + + thermal-zones { + thermal_d3 { + polling-delay-passive = <250>; + polling-delay = <1000>; + thermal-sensors = <&thermal_d3 0>; + trips { + thermal_d3_z0_crit { + temperature = <105000>; + hysteresis = <2000>; + type = "critical"; + }; + }; + }; + };