From patchwork Sun Jan 24 17:02:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Vasut X-Patchwork-Id: 12042529 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 C7AF5C433DB for ; Sun, 24 Jan 2021 17:04:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95AEB22CA2 for ; Sun, 24 Jan 2021 17:04:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726230AbhAXREX (ORCPT ); Sun, 24 Jan 2021 12:04:23 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:45619 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726173AbhAXREW (ORCPT ); Sun, 24 Jan 2021 12:04:22 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4DNzpT3xvlz1qsjq; Sun, 24 Jan 2021 18:03:13 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4DNzpT39Shz1tYWh; Sun, 24 Jan 2021 18:03:13 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id B9luffZZyPk5; Sun, 24 Jan 2021 18:03:12 +0100 (CET) X-Auth-Info: L0M/oZrwQYMgWrNB0X1JCV1bhtNsrieVCzPE2WKxE9A= Received: from tr.lan (ip-89-176-112-137.net.upcbroadband.cz [89.176.112.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Sun, 24 Jan 2021 18:03:12 +0100 (CET) From: Marek Vasut To: linux-mmc@vger.kernel.org Cc: Marek Vasut , Yann Gautier , Linus Walleij , Alexandre Torgue , Ludovic Barre , Ulf Hansson , linux-stm32@st-md-mailman.stormreply.com Subject: [PATCH V2 2/4] mmc: mmci: Add support for probing bus voltage level translator Date: Sun, 24 Jan 2021 18:02:56 +0100 Message-Id: <20210124170258.32862-2-marex@denx.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210124170258.32862-1-marex@denx.de> References: <20210124170258.32862-1-marex@denx.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org Add support for testing whether bus voltage level translator is present and operational. This is useful on systems where the bus voltage level translator is optional, as the translator can be auto-detected by the driver and the feedback clock functionality can be disabled if it is not present. This requires additional pinmux state, "init", where the CMD, CK, CKIN lines are not configured, so they can be claimed as GPIOs early on in probe(). The translator test sets CMD high to avoid interfering with a card, and then verifies whether signal set on CK is detected on CKIN. If the signal is detected, translator is present, otherwise the CKIN feedback clock are disabled. Tested-by: Yann Gautier Reviewed-by: Linus Walleij Signed-off-by: Marek Vasut Cc: Alexandre Torgue Cc: Linus Walleij Cc: Ludovic Barre Cc: Ulf Hansson Cc: linux-stm32@st-md-mailman.stormreply.com --- V2: Rebase on next-20210122, add TB and RB --- drivers/mmc/host/mmci.c | 70 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 5 deletions(-) diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index b5a41a7ce165..1bc674577ff9 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include @@ -1888,6 +1889,65 @@ static struct mmc_host_ops mmci_ops = { .start_signal_voltage_switch = mmci_sig_volt_switch, }; +static void mmci_probe_level_translator(struct mmc_host *mmc) +{ + struct device *dev = mmc_dev(mmc); + struct mmci_host *host = mmc_priv(mmc); + struct gpio_desc *cmd_gpio; + struct gpio_desc *ck_gpio; + struct gpio_desc *ckin_gpio; + int clk_hi, clk_lo; + + /* + * Assume the level translator is present if st,use-ckin is set. + * This is to cater for DTs which do not implement this test. + */ + host->clk_reg_add |= MCI_STM32_CLK_SELCKIN; + + cmd_gpio = gpiod_get(dev, "st,cmd", GPIOD_OUT_HIGH); + if (IS_ERR(cmd_gpio)) + goto exit_cmd; + + ck_gpio = gpiod_get(dev, "st,ck", GPIOD_OUT_HIGH); + if (IS_ERR(ck_gpio)) + goto exit_ck; + + ckin_gpio = gpiod_get(dev, "st,ckin", GPIOD_IN); + if (IS_ERR(ckin_gpio)) + goto exit_ckin; + + /* All GPIOs are valid, test whether level translator works */ + + /* Sample CKIN */ + clk_hi = !!gpiod_get_value(ckin_gpio); + + /* Set CK low */ + gpiod_set_value(ck_gpio, 0); + + /* Sample CKIN */ + clk_lo = !!gpiod_get_value(ckin_gpio); + + /* Tristate all */ + gpiod_direction_input(cmd_gpio); + gpiod_direction_input(ck_gpio); + + /* Level translator is present if CK signal is propagated to CKIN */ + if (!clk_hi || clk_lo) { + host->clk_reg_add &= ~MCI_STM32_CLK_SELCKIN; + dev_warn(dev, + "Level translator inoperable, CK signal not detected on CKIN, disabling.\n"); + } + + gpiod_put(ckin_gpio); + +exit_ckin: + gpiod_put(ck_gpio); +exit_ck: + gpiod_put(cmd_gpio); +exit_cmd: + pinctrl_select_default_state(dev); +} + static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc) { struct mmci_host *host = mmc_priv(mmc); @@ -1913,7 +1973,7 @@ static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc) if (of_get_property(np, "st,neg-edge", NULL)) host->clk_reg_add |= MCI_STM32_CLK_NEGEDGE; if (of_get_property(np, "st,use-ckin", NULL)) - host->clk_reg_add |= MCI_STM32_CLK_SELCKIN; + mmci_probe_level_translator(mmc); if (of_get_property(np, "mmc-cap-mmc-highspeed", NULL)) mmc->caps |= MMC_CAP_MMC_HIGHSPEED; @@ -1949,15 +2009,15 @@ static int mmci_probe(struct amba_device *dev, if (!mmc) return -ENOMEM; - ret = mmci_of_parse(np, mmc); - if (ret) - goto host_free; - host = mmc_priv(mmc); host->mmc = mmc; host->mmc_ops = &mmci_ops; mmc->ops = &mmci_ops; + ret = mmci_of_parse(np, mmc); + if (ret) + goto host_free; + /* * Some variant (STM32) doesn't have opendrain bit, nevertheless * pins can be set accordingly using pinctrl