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=-14.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNWANTED_LANGUAGE_BODY, USER_AGENT_GIT 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 A1AF4C07E99 for ; Mon, 5 Jul 2021 17:11:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B6266197C for ; Mon, 5 Jul 2021 17:11:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230002AbhGERNj (ORCPT ); Mon, 5 Jul 2021 13:13:39 -0400 Received: from foss.arm.com ([217.140.110.172]:51236 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229996AbhGERNf (ORCPT ); Mon, 5 Jul 2021 13:13:35 -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 958BD1042; Mon, 5 Jul 2021 10:10:58 -0700 (PDT) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DD71D3F694; Mon, 5 Jul 2021 10:10:56 -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: [RFC PATCH v2 8/8] firmware: arm_scmi: Make smc transport atomic Date: Mon, 5 Jul 2021 18:10:22 +0100 Message-Id: <20210705171022.25861-9-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210705171022.25861-1-cristian.marussi@arm.com> References: <20210705171022.25861-1-cristian.marussi@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 cab1d0d50d8e..e33985a02068 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; }; @@ -114,7 +117,7 @@ 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; @@ -133,6 +136,15 @@ 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) { @@ -140,16 +152,17 @@ 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; } @@ -168,7 +181,7 @@ 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 @@ -194,4 +207,5 @@ const struct scmi_desc scmi_smc_desc = { .max_rx_timeout_ms = 30, .max_msg = 20, .max_msg_size = 128, + .atomic_capable = true, }; -- 2.17.1