From patchwork Wed Feb 14 18:30:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cristian Marussi X-Patchwork-Id: 13556938 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AC156C48BC3 for ; Wed, 14 Feb 2024 18:31:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4EVKzfuXUF07WskvUgc/A/d2KYWfLJeWKhlS/p7GLeA=; b=L3FRtVL9Ot5i2v Ya0kZjFA0rsrmOj0lCdzvlYM/0ULwocbZ+Mw0V8BGGtd0VVVpGhEXT3o5iGBSUuQ8xeEdd2V3622J 4UtDZxy3SFIMDHZBCGTPhhJJka1rTl4wWWOAdw6FfkVfnbxCw33R4VZOyt2668MwtCUI6i01uXTfC JjwFwvt1ZTSF4RfYE2+I/COUe8VUMSC/m5aBITFuXXW/BfFSHd6HDOluGNWzlLMr9zHrZE6x1r4hy kPMwLqX/a5+RPboczyHx1FD/PIeHPeGDYocqQzVntLMzvLh3GXyR9lXPK6LVaomfAlFuOHbRvAEWh j6MycPqkDBKWzJgo8l8Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1raK1u-0000000DwX0-3wGQ; Wed, 14 Feb 2024 18:30:46 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1raK1l-0000000DwTF-44yD for linux-arm-kernel@lists.infradead.org; Wed, 14 Feb 2024 18:30:39 +0000 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 8B94A1476; Wed, 14 Feb 2024 10:31:15 -0800 (PST) Received: from pluto.fritz.box (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DC2173F7B4; Wed, 14 Feb 2024 10:30:32 -0800 (PST) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, peng.fan@oss.nxp.com, michal.simek@amd.com, quic_sibis@quicinc.com, quic_nkela@quicinc.com, souvik.chakravarty@arm.com, Cristian Marussi Subject: [PATCH 2/7] firmware: arm_scmi: Add support for v3.2 NEGOTIATE_PROTOCOL_VERSION Date: Wed, 14 Feb 2024 18:30:01 +0000 Message-ID: <20240214183006.3403207-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240214183006.3403207-1-cristian.marussi@arm.com> References: <20240214183006.3403207-1-cristian.marussi@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240214_103038_123487_0BFFA0D0 X-CRM114-Status: GOOD ( 18.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Freshly introduced NEGOTIATE_PROTOCOL_VERSION allows the agent to ascertain upfront if a specific, usually older, protocol version is supported by the platform. It is used by the agent in case the platform has advertised the support of a newer protocol version than the latest version supported by the agent, since backward compatibility cannot be automatically assumed. Emit a warning about possible incompatibility when negotiation was not possible or just print the successfully negotiated protocol. Signed-off-by: Cristian Marussi --- drivers/firmware/arm_scmi/driver.c | 65 ++++++++++++++++++++++++--- drivers/firmware/arm_scmi/protocols.h | 1 + 2 files changed, 61 insertions(+), 5 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 4a64ad5c21ee..34d77802c990 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -86,6 +86,12 @@ struct scmi_xfers_info { * @users: A refcount to track effective users of this protocol. * @priv: Reference for optional protocol private data. * @version: Protocol version supported by the platform as detected at runtime. + * @negotiated_version: When the platform supports a newer protocol version, + * the agent will try to negotiate with the platform the + * usage of the newest version known to it, since + * backward compatibility is NOT automatically assured. + * This field is NON-zero when a successful negotiation + * has completed. * @ph: An embedded protocol handle that will be passed down to protocol * initialization code to identify this instance. * @@ -99,6 +105,7 @@ struct scmi_protocol_instance { refcount_t users; void *priv; unsigned int version; + unsigned int negotiated_version; struct scmi_protocol_handle ph; }; @@ -1815,6 +1822,44 @@ scmi_revision_area_get(const struct scmi_protocol_handle *ph) return pi->handle->version; } +/** + * scmi_protocol_version_negotiate - Negotiate protocol version + * + * @ph: A reference to the protocol handle. + * + * An helper to negotiate a protocol version different from the latest + * advertised as supported from the platform: on Success backward + * compatibility is assured by the platform. + * + * Return: 0 on Success + */ +static int scmi_protocol_version_negotiate(struct scmi_protocol_handle *ph) +{ + int ret; + struct scmi_xfer *t; + struct scmi_protocol_instance *pi = ph_to_pi(ph); + + /* At first check if NEGOTIATE_PROTOCOL_VERSION is supported ... */ + ret = scmi_protocol_msg_check(ph, NEGOTIATE_PROTOCOL_VERSION, NULL); + if (ret) + return ret; + + /* ... then attempt protocol version negotiation */ + ret = xfer_get_init(ph, NEGOTIATE_PROTOCOL_VERSION, + sizeof(__le32), 0, &t); + if (ret) + return ret; + + put_unaligned_le32(pi->proto->supported_version, t->tx.buf); + ret = do_xfer(ph, t); + if (!ret) + pi->negotiated_version = pi->proto->supported_version; + + xfer_put(ph, t); + + return ret; +} + /** * scmi_alloc_init_protocol_instance - Allocate and initialize a protocol * instance descriptor. @@ -1887,11 +1932,21 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info, devres_close_group(handle->dev, pi->gid); dev_dbg(handle->dev, "Initialized protocol: 0x%X\n", pi->proto->id); - if (pi->version > proto->supported_version) - dev_warn(handle->dev, - "Detected UNSUPPORTED higher version 0x%X for protocol 0x%X." - "Backward compatibility is NOT assured.\n", - pi->version, pi->proto->id); + if (pi->version > proto->supported_version) { + ret = scmi_protocol_version_negotiate(&pi->ph); + if (!ret) { + dev_info(handle->dev, + "Protocol 0x%X successfully negotiated version 0x%X\n", + proto->id, pi->negotiated_version); + } else { + dev_warn(handle->dev, + "Detected UNSUPPORTED higher version 0x%X for protocol 0x%X.\n", + pi->version, pi->proto->id); + dev_warn(handle->dev, + "Trying version 0x%X. Backward compatibility is NOT assured.\n", + pi->proto->supported_version); + } + } return pi; diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h index 26a3edd49fea..693019fff0f6 100644 --- a/drivers/firmware/arm_scmi/protocols.h +++ b/drivers/firmware/arm_scmi/protocols.h @@ -33,6 +33,7 @@ enum scmi_common_cmd { PROTOCOL_VERSION = 0x0, PROTOCOL_ATTRIBUTES = 0x1, PROTOCOL_MESSAGE_ATTRIBUTES = 0x2, + NEGOTIATE_PROTOCOL_VERSION = 0x10, }; /**