From patchwork Sun Mar 7 17:07:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 395740 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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS 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 E7902C433DB for ; Sun, 7 Mar 2021 17:08:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D5306503E for ; Sun, 7 Mar 2021 17:08:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232548AbhCGRIW (ORCPT ); Sun, 7 Mar 2021 12:08:22 -0500 Received: from aposti.net ([89.234.176.197]:40130 "EHLO aposti.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232563AbhCGRIC (ORCPT ); Sun, 7 Mar 2021 12:08:02 -0500 From: Paul Cercueil To: Michael Turquette , Stephen Boyd , Ulf Hansson , Russell King Cc: od@zcrc.me, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, Paul Cercueil Subject: [PATCH 1/2] clk: Add clk_get_first_to_set_rate Date: Sun, 7 Mar 2021 17:07:41 +0000 Message-Id: <20210307170742.70949-2-paul@crapouillou.net> In-Reply-To: <20210307170742.70949-1-paul@crapouillou.net> References: <20210307170742.70949-1-paul@crapouillou.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org The purpose of this function is to be used along with the notifier mechanism. When a parent clock can see its rate externally changed at any moment, and a driver needs a specific clock rate to function, it can register a notifier on the parent clock, and call clk_set_rate() on the base clock to adjust its frequency according to the new parent clock. This works fine, until the base clock has the CLK_SET_RATE_PARENT flag set. In that case, calling clk_set_rate() on the base clock will call clk_set_rate() on the parent clock, which will trigger the notifier again, and we're in a loop. For that reason, we need to register the notifier on the parent clock of the first ancestor of the base clock that will effectively modify its rate when clk_set_rate() is called, which we can now obtain with clk_get_first_to_set_rate(). Signed-off-by: Paul Cercueil --- drivers/clk/clk.c | 9 +++++++++ include/linux/clk.h | 16 ++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 5052541a0986..3fd75e283482 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -2450,6 +2450,15 @@ struct clk *clk_get_parent(struct clk *clk) } EXPORT_SYMBOL_GPL(clk_get_parent); +struct clk *clk_get_first_to_set_rate(struct clk *clk) +{ + while (clk && (clk->core->flags & CLK_SET_RATE_PARENT)) + clk = clk_get_parent(clk); + + return clk; +} + + static struct clk_core *__clk_init_parent(struct clk_core *core) { u8 index = 0; diff --git a/include/linux/clk.h b/include/linux/clk.h index 266e8de3cb51..f0ea6ac6aa39 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -766,6 +766,17 @@ struct clk *clk_get_parent(struct clk *clk); */ struct clk *clk_get_sys(const char *dev_id, const char *con_id); +/** + * clk_get_first_to_set_rate - get a pointer to the clock that will + * effectively modify its rate when clk_set_rate(clk) is called + * (might be clk itself, or any ancestor) + * @clk: clock source + * + * Returns struct clk corresponding to the matched clock source, or + * NULL on error. + */ +struct clk *clk_get_first_to_set_rate(struct clk *clk); + /** * clk_save_context - save clock context for poweroff * @@ -928,6 +939,11 @@ static inline struct clk *clk_get_parent(struct clk *clk) return NULL; } +static inline struct clk *clk_get_first_to_set_rate(struct clk *clk) +{ + return NULL; +} + static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id) { return NULL; From patchwork Sun Mar 7 17:07:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 395739 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=-11.0 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 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 91866C4332D for ; Sun, 7 Mar 2021 17:08:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72CB96503E for ; Sun, 7 Mar 2021 17:08:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232565AbhCGRIW (ORCPT ); Sun, 7 Mar 2021 12:08:22 -0500 Received: from aposti.net ([89.234.176.197]:40154 "EHLO aposti.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232564AbhCGRIJ (ORCPT ); Sun, 7 Mar 2021 12:08:09 -0500 From: Paul Cercueil To: Michael Turquette , Stephen Boyd , Ulf Hansson , Russell King Cc: od@zcrc.me, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, Paul Cercueil Subject: [PATCH 2/2] mmc: jz4740: Add support for monitoring PLL clock rate changes Date: Sun, 7 Mar 2021 17:07:42 +0000 Message-Id: <20210307170742.70949-3-paul@crapouillou.net> In-Reply-To: <20210307170742.70949-1-paul@crapouillou.net> References: <20210307170742.70949-1-paul@crapouillou.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org The main PLL can have its rate changed at any moment. To keep the MMC clock running at a rate that fits the specifications, we need to recompute the MMC clock rate every time the PLL rate changes. Use a mutex to ensure that the MMC is idle before performing the PLL and MMC rate changes. Signed-off-by: Paul Cercueil --- drivers/mmc/host/jz4740_mmc.c | 70 ++++++++++++++++++++++++++++++++++- 1 file changed, 69 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c index b3c636edbb46..1197b8c6b6ed 100644 --- a/drivers/mmc/host/jz4740_mmc.c +++ b/drivers/mmc/host/jz4740_mmc.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -149,6 +150,10 @@ struct jz4740_mmc_host { struct platform_device *pdev; struct clk *clk; + atomic_t clk_mutex_count; + struct mutex clk_mutex; + struct notifier_block clock_nb; + enum jz4740_mmc_version version; int irq; @@ -338,6 +343,9 @@ static void jz4740_mmc_pre_request(struct mmc_host *mmc, struct jz4740_mmc_host *host = mmc_priv(mmc); struct mmc_data *data = mrq->data; + if (atomic_inc_and_test(&host->clk_mutex_count)) + mutex_lock(&host->clk_mutex); + if (!host->use_dma) return; @@ -353,6 +361,9 @@ static void jz4740_mmc_post_request(struct mmc_host *mmc, struct jz4740_mmc_host *host = mmc_priv(mmc); struct mmc_data *data = mrq->data; + if (atomic_dec_return(&host->clk_mutex_count) == -1) + mutex_unlock(&host->clk_mutex); + if (data && data->host_cookie != COOKIE_UNMAPPED) jz4740_mmc_dma_unmap(host, data); @@ -955,6 +966,48 @@ static const struct mmc_host_ops jz4740_mmc_ops = { .enable_sdio_irq = jz4740_mmc_enable_sdio_irq, }; +static inline struct jz4740_mmc_host * +jz4740_mmc_nb_get_priv(struct notifier_block *nb) +{ + return container_of(nb, struct jz4740_mmc_host, clock_nb); +} + +static struct clk *jz4740_mmc_get_parent_clk(struct clk *clk) +{ + /* + * Return the first clock above the one that will effectively modify + * its rate when clk_set_rate(clk) is called. + */ + clk = clk_get_first_to_set_rate(clk); + + return clk_get_parent(clk); +} + +static int jz4740_mmc_update_clk(struct notifier_block *nb, + unsigned long action, + void *data) +{ + struct jz4740_mmc_host *host = jz4740_mmc_nb_get_priv(nb); + + /* + * PLL may have changed its frequency; our clock may be running above + * spec. Wait until MMC is idle (using host->clk_mutex) before changing + * the PLL clock, and after it's done, reset our clock rate. + */ + + switch (action) { + case PRE_RATE_CHANGE: + mutex_lock(&host->clk_mutex); + break; + default: + clk_set_rate(host->clk, host->mmc->f_max); + mutex_unlock(&host->clk_mutex); + break; + } + + return NOTIFY_OK; +} + static const struct of_device_id jz4740_mmc_of_match[] = { { .compatible = "ingenic,jz4740-mmc", .data = (void *) JZ_MMC_JZ4740 }, { .compatible = "ingenic,jz4725b-mmc", .data = (void *)JZ_MMC_JZ4725B }, @@ -971,6 +1024,7 @@ static int jz4740_mmc_probe(struct platform_device* pdev) struct mmc_host *mmc; struct jz4740_mmc_host *host; const struct of_device_id *match; + struct clk *parent_clk; mmc = mmc_alloc_host(sizeof(struct jz4740_mmc_host), &pdev->dev); if (!mmc) { @@ -1058,12 +1112,24 @@ static int jz4740_mmc_probe(struct platform_device* pdev) goto err_free_irq; host->use_dma = !ret; + atomic_set(&host->clk_mutex_count, -1); + mutex_init(&host->clk_mutex); + host->clock_nb.notifier_call = jz4740_mmc_update_clk; + + parent_clk = jz4740_mmc_get_parent_clk(host->clk); + + ret = clk_notifier_register(parent_clk, &host->clock_nb); + if (ret) { + dev_err(&pdev->dev, "Unable to register clock notifier\n"); + goto err_release_dma; + } + platform_set_drvdata(pdev, host); ret = mmc_add_host(mmc); if (ret) { dev_err(&pdev->dev, "Failed to add mmc host: %d\n", ret); - goto err_release_dma; + goto err_unregister_clk_notifier; } dev_info(&pdev->dev, "Ingenic SD/MMC card driver registered\n"); @@ -1074,6 +1140,8 @@ static int jz4740_mmc_probe(struct platform_device* pdev) return 0; +err_unregister_clk_notifier: + clk_notifier_unregister(parent_clk, &host->clock_nb); err_release_dma: if (host->use_dma) jz4740_mmc_release_dma_channels(host);