mmc: sdhci-of-at91: introduce driver for the Atmel SDMMC

Introduce driver for he Atmel SDMMC available on sama5d2. It is a sdhci
compliant controller.
Signed-off-by: NLudovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/sdhci-atmel.txt

+* Atmel SDHCI controller
+
+This file documents the differences between the core properties in
+Documentation/devicetree/bindings/mmc/mmc.txt and the properties used by the
+sdhci-of-at91 driver.
+
+Required properties:
+- compatible:		Must be "atmel,sama5d2-sdhci".
+- clocks:		Phandlers to the clocks.
+- clock-names:		Must be "hclock", "multclk", "baseclk";
+
+
+Example:
+
+sdmmc0: sdio-host@a0000000 {
+	compatible = "atmel,sama5d2-sdhci";
+	reg = <0xa0000000 0x300>;
+	interrupts = <31 IRQ_TYPE_LEVEL_HIGH 0>;
+	clocks = <&sdmmc0_hclk>, <&sdmmc0_gclk>, <&main>;
+	clock-names = "hclock", "multclk", "baseclk";
+};

drivers/mmc/host/Kconfig

@@ -129,6 +129,14 @@ config MMC_SDHCI_OF_ARASAN
 
 	  If unsure, say N.
 
+config MMC_SDHCI_OF_AT91
+	tristate "SDHCI OF support for the Atmel SDMMC controller"
+	depends on MMC_SDHCI_PLTFM
+	depends on OF
+	select MMC_SDHCI_IO_ACCESSORS
+	help
+	  This selects the Atmel SDMMC driver
+
 config MMC_SDHCI_OF_ESDHC
 	tristate "SDHCI OF support for the Freescale eSDHC controller"
 	depends on MMC_SDHCI_PLTFM

drivers/mmc/host/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_MMC_SDHCI_ESDHC_IMX)	+= sdhci-esdhc-imx.o
 obj-$(CONFIG_MMC_SDHCI_DOVE)		+= sdhci-dove.o
 obj-$(CONFIG_MMC_SDHCI_TEGRA)		+= sdhci-tegra.o
 obj-$(CONFIG_MMC_SDHCI_OF_ARASAN)	+= sdhci-of-arasan.o
+obj-$(CONFIG_MMC_SDHCI_OF_AT91)		+= sdhci-of-at91.o
 obj-$(CONFIG_MMC_SDHCI_OF_ESDHC)	+= sdhci-of-esdhc.o
 obj-$(CONFIG_MMC_SDHCI_OF_HLWD)		+= sdhci-of-hlwd.o
 obj-$(CONFIG_MMC_SDHCI_BCM_KONA)	+= sdhci-bcm-kona.o

drivers/mmc/host/sdhci-of-at91.c

+/*
+ * Atmel SDMMC controller driver.
+ *
+ * Copyright (C) 2015 Atmel,
+ *		 2015 Ludovic Desroches <ludovic.desroches@atmel.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mmc/host.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include "sdhci-pltfm.h"
+
+#define SDMMC_CACR	0x230
+#define		SDMMC_CACR_CAPWREN	BIT(0)
+#define		SDMMC_CACR_KEY		(0x46 << 8)
+
+struct sdhci_at91_priv {
+	struct clk *hclock;
+	struct clk *gck;
+	struct clk *mainck;
+};
+
+static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
+	.set_clock		= sdhci_set_clock,
+	.set_bus_width		= sdhci_set_bus_width,
+	.reset			= sdhci_reset,
+	.set_uhs_signaling	= sdhci_set_uhs_signaling,
+};
+
+static const struct sdhci_pltfm_data soc_data_sama5d2 = {
+	.ops = &sdhci_at91_sama5d2_ops,
+};
+
+static const struct of_device_id sdhci_at91_dt_match[] = {
+	{ .compatible = "atmel,sama5d2-sdhci", .data = &soc_data_sama5d2 },
+	{}
+};
+
+static int sdhci_at91_probe(struct platform_device *pdev)
+{
+	const struct of_device_id	*match;
+	const struct sdhci_pltfm_data	*soc_data;
+	struct sdhci_host		*host;
+	struct sdhci_pltfm_host		*pltfm_host;
+	struct sdhci_at91_priv		*priv;
+	unsigned int			caps0, caps1;
+	unsigned int			clk_base, clk_mul;
+	unsigned int			gck_rate, real_gck_rate;
+	int				ret;
+
+	match = of_match_device(sdhci_at91_dt_match, &pdev->dev);
+	if (!match)
+		return -EINVAL;
+	soc_data = match->data;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(&pdev->dev, "unable to allocate private data\n");
+		return -ENOMEM;
+	}
+
+	priv->mainck = devm_clk_get(&pdev->dev, "baseclk");
+	if (IS_ERR(priv->mainck)) {
+		dev_err(&pdev->dev, "failed to get baseclk\n");
+		return PTR_ERR(priv->mainck);
+	}
+
+	priv->hclock = devm_clk_get(&pdev->dev, "hclock");
+	if (IS_ERR(priv->hclock)) {
+		dev_err(&pdev->dev, "failed to get hclock\n");
+		return PTR_ERR(priv->hclock);
+	}
+
+	priv->gck = devm_clk_get(&pdev->dev, "multclk");
+	if (IS_ERR(priv->gck)) {
+		dev_err(&pdev->dev, "failed to get multclk\n");
+		return PTR_ERR(priv->gck);
+	}
+
+	host = sdhci_pltfm_init(pdev, soc_data, 0);
+	if (IS_ERR(host))
+		return PTR_ERR(host);
+
+	/*
+	 * The mult clock is provided by as a generated clock by the PMC
+	 * controller. In order to set the rate of gck, we have to get the
+	 * base clock rate and the clock mult from capabilities.
+	 */
+	clk_prepare_enable(priv->hclock);
+	caps0 = readl(host->ioaddr + SDHCI_CAPABILITIES);
+	caps1 = readl(host->ioaddr + SDHCI_CAPABILITIES_1);
+	clk_base = (caps0 & SDHCI_CLOCK_V3_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
+	clk_mul = (caps1 & SDHCI_CLOCK_MUL_MASK) >> SDHCI_CLOCK_MUL_SHIFT;
+	gck_rate = clk_base * 1000000 * (clk_mul + 1);
+	ret = clk_set_rate(priv->gck, gck_rate);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to set gck");
+		goto hclock_disable_unprepare;
+		return -EINVAL;
+	}
+	/*
+	 * We need to check if we have the requested rate for gck because in
+	 * some cases this rate could be not supported. If it happens, the rate
+	 * is the closest one gck can provide. We have to update the value
+	 * of clk mul.
+	 */
+	real_gck_rate = clk_get_rate(priv->gck);
+	if (real_gck_rate != gck_rate) {
+		clk_mul = real_gck_rate / (clk_base * 1000000) - 1;
+		caps1 &= (~SDHCI_CLOCK_MUL_MASK);
+		caps1 |= ((clk_mul << SDHCI_CLOCK_MUL_SHIFT) & SDHCI_CLOCK_MUL_MASK);
+		/* Set capabilities in r/w mode. */
+		writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN, host->ioaddr + SDMMC_CACR);
+		writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
+		/* Set capabilities in ro mode. */
+		writel(0, host->ioaddr + SDMMC_CACR);
+		dev_info(&pdev->dev, "update clk mul to %u as gck rate is %u Hz\n",
+			 clk_mul, real_gck_rate);
+	}
+
+	clk_prepare_enable(priv->mainck);
+	clk_prepare_enable(priv->gck);
+
+	pltfm_host = sdhci_priv(host);
+	pltfm_host->priv = priv;
+
+	ret = mmc_of_parse(host->mmc);
+	if (ret)
+		goto clocks_disable_unprepare;
+
+	sdhci_get_of_property(pdev);
+
+	ret = sdhci_add_host(host);
+	if (ret)
+		goto clocks_disable_unprepare;
+
+	return 0;
+
+clocks_disable_unprepare:
+	clk_disable_unprepare(priv->gck);
+	clk_disable_unprepare(priv->mainck);
+hclock_disable_unprepare:
+	clk_disable_unprepare(priv->hclock);
+	sdhci_pltfm_free(pdev);
+	return ret;
+}
+
+static int sdhci_at91_remove(struct platform_device *pdev)
+{
+	struct sdhci_host	*host = platform_get_drvdata(pdev);
+	struct sdhci_pltfm_host	*pltfm_host = sdhci_priv(host);
+	struct sdhci_at91_priv	*priv = pltfm_host->priv;
+
+	sdhci_pltfm_unregister(pdev);
+
+	clk_disable_unprepare(priv->gck);
+	clk_disable_unprepare(priv->hclock);
+	clk_disable_unprepare(priv->mainck);
+
+	return 0;
+}
+
+static struct platform_driver sdhci_at91_driver = {
+	.driver		= {
+		.name	= "sdhci-at91",
+		.owner	= THIS_MODULE,
+		.of_match_table = sdhci_at91_dt_match,
+		.pm	= SDHCI_PLTFM_PMOPS,
+	},
+	.probe		= sdhci_at91_probe,
+	.remove		= sdhci_at91_remove,
+};
+
+module_platform_driver(sdhci_at91_driver);
+
+MODULE_DESCRIPTION("SDHCI driver for at91");
+MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@atmel.com>");
+MODULE_LICENSE("GPL v2");