From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0B7CC32792 for ; Mon, 30 Sep 2019 14:26:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F96F21906 for ; Mon, 30 Sep 2019 14:26:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731764AbfI3O0s (ORCPT ); Mon, 30 Sep 2019 10:26:48 -0400 Received: from foss.arm.com ([217.140.110.172]:55616 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731276AbfI3O0r (ORCPT ); Mon, 30 Sep 2019 10:26:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 18DD228; Mon, 30 Sep 2019 07:26:47 -0700 (PDT) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9E2FF3F706; Mon, 30 Sep 2019 07:26:45 -0700 (PDT) Date: Mon, 30 Sep 2019 15:26:40 +0100 From: Sudeep Holla To: Peng Fan Cc: "robh+dt@kernel.org" , "mark.rutland@arm.com" , "jassisinghbrar@gmail.com" , "andre.przywara@arm.com" , "f.fainelli@gmail.com" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , dl-linux-imx , Sudeep Holla Subject: Re: [PATCH V10 1/2] dt-bindings: mailbox: add binding doc for the ARM SMC/HVC mailbox Message-ID: <20190930142640.GA24945@bogus> References: <1569824287-4263-1-git-send-email-peng.fan@nxp.com> <1569824287-4263-2-git-send-email-peng.fan@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1569824287-4263-2-git-send-email-peng.fan@nxp.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 30, 2019 at 06:20:09AM +0000, Peng Fan wrote: > From: Peng Fan > > The ARM SMC/HVC mailbox binding describes a firmware interface to trigger > actions in software layers running in the EL2 or EL3 exception levels. > The term "ARM" here relates to the SMC instruction as part of the ARM > instruction set, not as a standard endorsed by ARM Ltd. > FWIW: Reviewed-by: Sudeep Holla > Reviewed-by: Rob Herring > Reviewed-by: Andre Przywara > Reviewed-by: Florian Fainelli > Signed-off-by: Peng Fan > --- > .../devicetree/bindings/mailbox/arm-smc.yaml | 96 ++++++++++++++++++++++ > 1 file changed, 96 insertions(+) > create mode 100644 Documentation/devicetree/bindings/mailbox/arm-smc.yaml > > diff --git a/Documentation/devicetree/bindings/mailbox/arm-smc.yaml b/Documentation/devicetree/bindings/mailbox/arm-smc.yaml > new file mode 100644 > index 000000000000..c165946a64e4 > --- /dev/null > +++ b/Documentation/devicetree/bindings/mailbox/arm-smc.yaml > @@ -0,0 +1,96 @@ > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/mailbox/arm-smc.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: ARM SMC Mailbox Interface > + > +maintainers: > + - Peng Fan > + > +description: | > + This mailbox uses the ARM smc (secure monitor call) or hvc (hypervisor > + call) instruction to trigger a mailbox-connected activity in firmware, > + executing on the very same core as the caller. The value of r0/w0/x0 > + the firmware returns after the smc call is delivered as a received > + message to the mailbox framework, so synchronous communication can be > + established. The exact meaning of the action the mailbox triggers as > + well as the return value is defined by their users and is not subject > + to this binding. > + > + One example use case of this mailbox is the SCMI interface, which uses > + shared memory to transfer commands and parameters, and a mailbox to > + trigger a function call. This allows SoCs without a separate management > + processor (or when such a processor is not available or used) to use > + this standardized interface anyway. > + > + This binding describes no hardware, but establishes a firmware interface. > + Upon receiving an SMC using the described SMC function identifier, the > + firmware is expected to trigger some mailbox connected functionality. > + The communication follows the ARM SMC calling convention. > + Firmware expects an SMC function identifier in r0 or w0. The supported > + identifier is listed in the the arm,func-id property as described below. > + The firmware can return one value in the first SMC result register, > + it is expected to be an error value, which shall be propagated to the > + mailbox client. > + > + Any core which supports the SMC or HVC instruction can be used, as long > + as a firmware component running in EL3 or EL2 is handling these calls. > + > +properties: > + compatible: > + oneOf: > + - description: > + For implementations using ARM SMC instruction. > + const: arm,smc-mbox > + > + - description: > + For implementations using ARM HVC instruction. > + const: arm,hvc-mbox > + > + "#mbox-cells": > + const: 0 > + > + arm,func-id: > + description: | > + An single 32-bit value specifying the function ID used by the mailbox. > + The function ID follows the ARM SMC calling convention standard. > + $ref: /schemas/types.yaml#/definitions/uint32 > + > +required: > + - compatible > + - "#mbox-cells" > + - arm,func-id > + > +examples: > + - | > + sram@93f000 { > + compatible = "mmio-sram"; > + reg = <0x0 0x93f000 0x0 0x1000>; > + #address-cells = <1>; > + #size-cells = <1>; > + ranges = <0x0 0x93f000 0x1000>; > + > + cpu_scp_lpri: scp-shmem@0 { > + compatible = "arm,scmi-shmem"; > + reg = <0x0 0x200>; > + }; > + }; > + > + smc_tx_mbox: tx_mbox { [nit] ^^^^^^^^^ s/tx_mbox/mailbox/ ? mailbox sounds more generic name to use, you can always use what ever name in the label. This is not a must change, just thought of mentioning as the pattern followed is to use generic names. -- Regards, Sudeep