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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 11C39C43463 for ; Fri, 18 Sep 2020 16:33:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8E76208DB for ; Fri, 18 Sep 2020 16:33:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726393AbgIRQdN (ORCPT ); Fri, 18 Sep 2020 12:33:13 -0400 Received: from plasma31.jpberlin.de ([80.241.56.82]:27825 "EHLO plasma31.jpberlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbgIRQdN (ORCPT ); Fri, 18 Sep 2020 12:33:13 -0400 X-Greylist: delayed 400 seconds by postgrey-1.27 at vger.kernel.org; Fri, 18 Sep 2020 12:33:11 EDT Received: from spamfilter03.heinlein-hosting.de (spamfilter03.heinlein-hosting.de [80.241.56.117]) by plasma.jpberlin.de (Postfix) with ESMTP id 810E01025E4; Fri, 18 Sep 2020 18:26:26 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from plasma.jpberlin.de ([80.241.56.76]) by spamfilter03.heinlein-hosting.de (spamfilter03.heinlein-hosting.de [80.241.56.117]) (amavisd-new, port 10030) with ESMTP id BIAa6MxQyu22; Fri, 18 Sep 2020 18:26:24 +0200 (CEST) Received: from webmail.opensynergy.com (unknown [217.66.60.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client CN "*.opensynergy.com", Issuer "Starfield Secure Certificate Authority - G2" (not verified)) (Authenticated sender: opensynergy@jpberlin.de) by plasma.jpberlin.de (Postfix) with ESMTPSA id B07F7100971; Fri, 18 Sep 2020 18:26:23 +0200 (CEST) From: Peter Hilber To: , , , CC: Rob Herring , , , , , , , , , Peter Hilber , Jason Wang , Jassi Brar , Lorenzo Pieralisi , Mark Rutland , "Michael S. Tsirkin" Subject: [RFC PATCH 0/7] firmware: arm_scmi: Add virtio transport Date: Fri, 18 Sep 2020 18:23:09 +0200 Message-ID: <20200918162311.254564-1-peter.hilber@opensynergy.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-ClientProxiedBy: SR-MAIL-01.open-synergy.com (10.26.10.21) To SR-MAIL-01.open-synergy.com (10.26.10.21) X-MBO-SPAM-Probability: X-Rspamd-Score: -3.87 / 15.00 / 15.00 X-Rspamd-Queue-Id: 810E01025E4 X-Rspamd-UID: d4e547 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org This series implements an SCMI virtio driver according to the virtio SCMI device spec patch v5 [1], after simple preparatory changes to the existing arm-scmi driver. The virtio transport differs in some respects from the existing shared-memory based SCMI transports. Message timeouts can be a problem if the virtio device (SCMI platform) does not have real-time properties. I set a high message rx timeout value which should work for non real-time virtio devices as well. There are other timeouts for delayed response and polling which were not addressed yet. Delayed responses are not really needed since, with the virtio transport, message responses may be transmitted out of order. Polling doesn't make sense at least for virtio devices without real-time behavior, in my understanding. There are some known issues which will be resolved before removing the RFC tag: - Further work is needed on the scmi_xfer management. Unlike shmem based transports, the virtio transport is actually exchanging messages with the SCMI agent through the scmi_xfer tx and rx buffers. In case of a message rx timeout, the arm-scmi driver could try to re-use the scmi_xfer, while that might still be used by the virtio device. I think part of the scmi_xfers_info bookkeeping could be optionally outsourced to the transport to remediate this. - After arm-scmi driver probe failure, or after remove, the scmi-virtio driver may still try to process and forward message responses from the virtio device. - We must be sure that the virtio transport option (such as virtio over MMIO) is available when the virtio SCMI device is probed. The series is based on for-next/scmi [2], on top of commit 66d90f6ecee7 ("firmware: arm_scmi: Enable building as a single module") The series was actually tested with a v5.4 based kernel, with the Base protocol and Sensor management protocol. The virtio SCMI device used was a proprietary implementation by OpenSynergy. Delayed responses were not tested. Any comments are very welcome. [1] https://lists.oasis-open.org/archives/virtio-comment/202005/msg00096.html [2] https://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux.git Igor Skalkin (7): firmware: arm_scmi, smccc, mailbox: Make shmem based transports optional firmware: arm_scmi: Document that max_msg is a per channel type limit firmware: arm_scmi: Add op to override max message # firmware: arm_scmi: Add per message transport data firmware: arm_scmi: Add xfer_init_buffers transport op dt-bindings: arm: Add virtio transport for SCMI firmware: arm_scmi: Add virtio transport .../devicetree/bindings/arm/arm,scmi.txt | 38 +- MAINTAINERS | 1 + drivers/firmware/Kconfig | 19 +- drivers/firmware/arm_scmi/Makefile | 3 +- drivers/firmware/arm_scmi/common.h | 31 +- drivers/firmware/arm_scmi/driver.c | 83 +++- drivers/firmware/arm_scmi/virtio.c | 470 ++++++++++++++++++ drivers/firmware/smccc/Kconfig | 1 + drivers/mailbox/Kconfig | 1 + include/uapi/linux/virtio_ids.h | 1 + include/uapi/linux/virtio_scmi.h | 41 ++ 11 files changed, 664 insertions(+), 25 deletions(-) create mode 100644 drivers/firmware/arm_scmi/virtio.c create mode 100644 include/uapi/linux/virtio_scmi.h base-commit: 66d90f6ecee755e9c19a119c9255e80091165498 -- 2.25.1