From patchwork Mon Jul 12 16:26:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cristian Marussi X-Patchwork-Id: 12371517 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=-14.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 2B18CC07E99 for ; Mon, 12 Jul 2021 16:32:37 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id DF672611CC for ; Mon, 12 Jul 2021 16:32:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DF672611CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id: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=ap7tfkCGf0q384T/TN+YjXEgUt+eLAPTUTtippLzCtk=; b=J+OHixvsTSj/KU 3t09fY2XMAslTZ4G8oQTtOe3k3UL0nq6zg86msJ83J8PnqTFcAM1A7RGTponihm/p4FO0s11wBCwQ 7mqxoDx4ZNgr1VCFg2VVM6BpiLQuYFuzeCCvgTb+hV2jdhKv4Xt1nl4c3toC7frQPW6qXHbqR+Wz1 nFkEaWbgXhbR32MlrUySaFyKUp/Gg/jbJ6t6g/V4hagFCFyzeXDL3IDOFfqT8CbzLWCGJbY7juqc6 vHmEOoXkjGvpti8Q8Z1D2h+EZhf1NiOB5UJexabAdEwasJKAXvYR8aB0b917LklFn25STj/eKWc00 EXrxN898bK+OyPxq7pCg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m2ypV-007v7A-BO; Mon, 12 Jul 2021 16:30:50 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m2ylr-007tNf-K4 for linux-arm-kernel@lists.infradead.org; Mon, 12 Jul 2021 16:27:05 +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 53C6431B; Mon, 12 Jul 2021 09:27:02 -0700 (PDT) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 86AD63F774; Mon, 12 Jul 2021 09:27:00 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com, cristian.marussi@arm.com Subject: [PATCH v3 8/8] [RFC] firmware: arm_scmi: Make smc transport atomic Date: Mon, 12 Jul 2021 17:26:25 +0100 Message-Id: <20210712162626.34705-9-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210712162626.34705-1-cristian.marussi@arm.com> References: <20210712162626.34705-1-cristian.marussi@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210712_092703_811484_DA90AF7B X-CRM114-Status: GOOD ( 12.82 ) 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: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Substitute mutex usages with busy-waiting and declare smc transport as .atomic_capable. Signed-off-by: Cristian Marussi --- drivers/firmware/arm_scmi/smc.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c index ec895a82a9ad..8c6e21b04767 100644 --- a/drivers/firmware/arm_scmi/smc.c +++ b/drivers/firmware/arm_scmi/smc.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -14,6 +15,7 @@ #include #include #include +#include #include #include "common.h" @@ -23,14 +25,15 @@ * * @cinfo: SCMI channel info * @shmem: Transmit/Receive shared memory area - * @shmem_lock: Lock to protect access to Tx/Rx shared memory area + * @inflight: Atomic flag to protect access to Tx/Rx shared memory area * @func_id: smc/hvc call function id */ struct scmi_smc { struct scmi_chan_info *cinfo; struct scmi_shared_mem __iomem *shmem; - struct mutex shmem_lock; +#define INFLIGHT_NONE MSG_TOKEN_MAX + atomic_t inflight; u32 func_id; }; @@ -115,7 +118,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, scmi_info->func_id = func_id; scmi_info->cinfo = cinfo; - mutex_init(&scmi_info->shmem_lock); + atomic_set(&scmi_info->inflight, INFLIGHT_NONE); cinfo->transport_info = scmi_info; return 0; @@ -134,6 +137,15 @@ static int smc_chan_free(int id, void *p, void *data) return 0; } +static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight) +{ + int ret; + + ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq); + + return ret == INFLIGHT_NONE; +} + static int smc_send_message(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) { @@ -141,17 +153,18 @@ static int smc_send_message(struct scmi_chan_info *cinfo, struct arm_smccc_res res; /* - * Channel lock will be released only once response has been + * Channel will be released only once response has been * surely fully retrieved, so after .mark_txdone() */ - mutex_lock(&scmi_info->shmem_lock); + spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight)); + shmem_tx_prepare(scmi_info->shmem, xfer); arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res); /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */ if (res.a0) { - mutex_unlock(&scmi_info->shmem_lock); + atomic_set(&scmi_info->inflight, INFLIGHT_NONE); return -EOPNOTSUPP; } @@ -170,7 +183,7 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret) { struct scmi_smc *scmi_info = cinfo->transport_info; - mutex_unlock(&scmi_info->shmem_lock); + atomic_set(&scmi_info->inflight, INFLIGHT_NONE); } static bool @@ -196,4 +209,5 @@ const struct scmi_desc scmi_smc_desc = { .max_rx_timeout_ms = 30, .max_msg = 20, .max_msg_size = 128, + .atomic_capable = true, };