mmc: dw_mmc: add support for exynos specific implementation of dw-mshc

Samsung Exynos SoC's extend the dw-mshc controller for additional clock
and bus control. Add support for these extensions and include provide
device tree based discovery suppory as well.
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt

+* Samsung Exynos specific extensions to the Synopsis Designware Mobile
+  Storage Host Controller
+
+The Synopsis designware mobile storage host controller is used to interface
+a SoC with storage medium such as eMMC or SD/MMC cards. This file documents
+differences between the core Synopsis dw mshc controller properties described
+by synposis-dw-mshc.txt and the properties used by the Samsung Exynos specific
+extensions to the Synopsis Designware Mobile Storage Host Controller.
+
+Required Properties:
+
+* compatible: should be
+	- "samsung,exynos4210-dw-mshc": for controllers with Samsung Exynos4210
+	  specific extentions.
+	- "samsung,exynos4412-dw-mshc": for controllers with Samsung Exynos4412
+	  specific extentions.
+	- "samsung,exynos5250-dw-mshc": for controllers with Samsung Exynos5250
+	  specific extentions.
+
+* samsung,dw-mshc-ciu-div: Specifies the divider value for the card interface
+  unit (ciu) clock. This property is applicable only for Exynos5 SoC's and
+  ignored for Exynos4 SoC's. The valid range of divider value is 0 to 7.
+
+* samsung,dw-mshc-sdr-timing: Specifies the value of CIU clock phase shift value
+  in transmit mode and CIU clock phase shift value in receive mode for single
+  data rate mode operation. Refer notes below for the order of the cells and the
+  valid values.
+
+* samsung,dw-mshc-ddr-timing: Specifies the value of CUI clock phase shift value
+  in transmit mode and CIU clock phase shift value in receive mode for double
+  data rate mode operation. Refer notes below for the order of the cells and the
+  valid values.
+
+  Notes for the sdr-timing and ddr-timing values:
+
+    The order of the cells should be
+      - First Cell: CIU clock phase shift value for tx mode.
+      - Second Cell: CIU clock phase shift value for rx mode.
+
+    Valid values for SDR and DDR CIU clock timing for Exynos5250:
+      - valid value for tx phase shift and rx phase shift is 0 to 7.
+      - when CIU clock divider value is set to 3, all possible 8 phase shift
+        values can be used.
+      - if CIU clock divider value is 0 (that is divide by 1), both tx and rx
+        phase shift clocks should be 0.
+
+Required properties for a slot:
+
+* gpios: specifies a list of gpios used for command, clock and data bus. The
+  first gpio is the command line and the second gpio is the clock line. The
+  rest of the gpios (depending on the bus-width property) are the data lines in
+  no particular order. The format of the gpio specifier depends on the gpio
+  controller.
+
+Example:
+
+  The MSHC controller node can be split into two portions, SoC specific and
+  board specific portions as listed below.
+
+	dwmmc0@12200000 {
+		compatible = "samsung,exynos5250-dw-mshc";
+		reg = <0x12200000 0x1000>;
+		interrupts = <0 75 0>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
+
+	dwmmc0@12200000 {
+		num-slots = <1>;
+		supports-highspeed;
+		broken-cd;
+		fifo-depth = <0x80>;
+		card-detect-delay = <200>;
+		samsung,dw-mshc-ciu-div = <3>;
+		samsung,dw-mshc-sdr-timing = <2 3>;
+		samsung,dw-mshc-ddr-timing = <1 2>;
+
+		slot@0 {
+			reg = <0>;
+			bus-width = <8>;
+			gpios = <&gpc0 0 2 0 3>, <&gpc0 1 2 0 3>,
+				<&gpc1 0 2 3 3>, <&gpc1 1 2 3 3>,
+				<&gpc1 2 2 3 3>, <&gpc1 3 2 3 3>,
+				<&gpc0 3 2 3 3>, <&gpc0 4 2 3 3>,
+				<&gpc0 5 2 3 3>, <&gpc0 6 2 3 3>;
+		};
+	};

drivers/mmc/host/Kconfig

@@ -540,6 +540,15 @@ config MMC_DW_PLTFM
 
 	  If unsure, say Y.
 
+config MMC_DW_EXYNOS
+	tristate "Exynos specific extentions for Synopsys DW Memory Card Interface"
+	depends on MMC_DW
+	select MMC_DW_PLTFM
+	help
+	  This selects support for Samsung Exynos SoC specific extensions to the
+	  Synopsys DesignWare Memory Card Interface driver. Select this option
+	  for platforms based on Exynos4 and Exynos5 SoC's.
+
 config MMC_DW_PCI
 	tristate "Synopsys Designware MCI support on PCI bus"
 	depends on MMC_DW && PCI

drivers/mmc/host/Makefile

@@ -39,6 +39,7 @@ obj-$(CONFIG_MMC_VIA_SDMMC)	+= via-sdmmc.o
 obj-$(CONFIG_SDH_BFIN)		+= bfin_sdh.o
 obj-$(CONFIG_MMC_DW)		+= dw_mmc.o
 obj-$(CONFIG_MMC_DW_PLTFM)	+= dw_mmc-pltfm.o
+obj-$(CONFIG_MMC_DW_EXYNOS)	+= dw_mmc-exynos.o
 obj-$(CONFIG_MMC_DW_PCI)	+= dw_mmc-pci.o
 obj-$(CONFIG_MMC_SH_MMCIF)	+= sh_mmcif.o
 obj-$(CONFIG_MMC_JZ4740)	+= jz4740_mmc.o

drivers/mmc/host/dw_mmc-exynos.c

+/*
+ * Exynos Specific Extensions for Synopsys DW Multimedia Card Interface driver
+ *
+ * Copyright (C) 2012, Samsung Electronics Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/dw_mmc.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+
+#include "dw_mmc.h"
+#include "dw_mmc-pltfm.h"
+
+#define NUM_PINS(x)			(x + 2)
+
+#define SDMMC_CLKSEL			0x09C
+#define SDMMC_CLKSEL_CCLK_SAMPLE(x)	(((x) & 7) << 0)
+#define SDMMC_CLKSEL_CCLK_DRIVE(x)	(((x) & 7) << 16)
+#define SDMMC_CLKSEL_CCLK_DIVIDER(x)	(((x) & 7) << 24)
+#define SDMMC_CLKSEL_GET_DRV_WD3(x)	(((x) >> 16) & 0x7)
+#define SDMMC_CLKSEL_TIMING(x, y, z)	(SDMMC_CLKSEL_CCLK_SAMPLE(x) |	\
+					SDMMC_CLKSEL_CCLK_DRIVE(y) |	\
+					SDMMC_CLKSEL_CCLK_DIVIDER(z))
+
+#define SDMMC_CMD_USE_HOLD_REG		BIT(29)
+
+#define EXYNOS4210_FIXED_CIU_CLK_DIV	2
+#define EXYNOS4412_FIXED_CIU_CLK_DIV	4
+
+/* Variations in Exynos specific dw-mshc controller */
+enum dw_mci_exynos_type {
+	DW_MCI_TYPE_EXYNOS4210,
+	DW_MCI_TYPE_EXYNOS4412,
+	DW_MCI_TYPE_EXYNOS5250,
+};
+
+/* Exynos implementation specific driver private data */
+struct dw_mci_exynos_priv_data {
+	enum dw_mci_exynos_type		ctrl_type;
+	u8				ciu_div;
+	u32				sdr_timing;
+	u32				ddr_timing;
+};
+
+static struct dw_mci_exynos_compatible {
+	char				*compatible;
+	enum dw_mci_exynos_type		ctrl_type;
+} exynos_compat[] = {
+	{
+		.compatible	= "samsung,exynos4210-dw-mshc",
+		.ctrl_type	= DW_MCI_TYPE_EXYNOS4210,
+	}, {
+		.compatible	= "samsung,exynos4412-dw-mshc",
+		.ctrl_type	= DW_MCI_TYPE_EXYNOS4412,
+	}, {
+		.compatible	= "samsung,exynos5250-dw-mshc",
+		.ctrl_type	= DW_MCI_TYPE_EXYNOS5250,
+	},
+};
+
+static int dw_mci_exynos_priv_init(struct dw_mci *host)
+{
+	struct dw_mci_exynos_priv_data *priv;
+	int idx;
+
+	priv = devm_kzalloc(host->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(host->dev, "mem alloc failed for private data\n");
+		return -ENOMEM;
+	}
+
+	for (idx = 0; idx < ARRAY_SIZE(exynos_compat); idx++) {
+		if (of_device_is_compatible(host->dev->of_node,
+					exynos_compat[idx].compatible))
+			priv->ctrl_type = exynos_compat[idx].ctrl_type;
+	}
+
+	host->priv = priv;
+	return 0;
+}
+
+static int dw_mci_exynos_setup_clock(struct dw_mci *host)
+{
+	struct dw_mci_exynos_priv_data *priv = host->priv;
+
+	if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS5250)
+		host->bus_hz /= (priv->ciu_div + 1);
+	else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4412)
+		host->bus_hz /= EXYNOS4412_FIXED_CIU_CLK_DIV;
+	else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4210)
+		host->bus_hz /= EXYNOS4210_FIXED_CIU_CLK_DIV;
+
+	return 0;
+}
+
+static void dw_mci_exynos_prepare_command(struct dw_mci *host, u32 *cmdr)
+{
+	/*
+	 * Exynos4412 and Exynos5250 extends the use of CMD register with the
+	 * use of bit 29 (which is reserved on standard MSHC controllers) for
+	 * optionally bypassing the HOLD register for command and data. The
+	 * HOLD register should be bypassed in case there is no phase shift
+	 * applied on CMD/DATA that is sent to the card.
+	 */
+	if (SDMMC_CLKSEL_GET_DRV_WD3(mci_readl(host, CLKSEL)))
+		*cmdr |= SDMMC_CMD_USE_HOLD_REG;
+}
+
+static void dw_mci_exynos_set_ios(struct dw_mci *host, struct mmc_ios *ios)
+{
+	struct dw_mci_exynos_priv_data *priv = host->priv;
+
+	if (ios->timing == MMC_TIMING_UHS_DDR50)
+		mci_writel(host, CLKSEL, priv->ddr_timing);
+	else
+		mci_writel(host, CLKSEL, priv->sdr_timing);
+}
+
+static int dw_mci_exynos_parse_dt(struct dw_mci *host)
+{
+	struct dw_mci_exynos_priv_data *priv = host->priv;
+	struct device_node *np = host->dev->of_node;
+	u32 timing[2];
+	u32 div = 0;
+	int ret;
+
+	of_property_read_u32(np, "samsung,dw-mshc-ciu-div", &div);
+	priv->ciu_div = div;
+
+	ret = of_property_read_u32_array(np,
+			"samsung,dw-mshc-sdr-timing", timing, 2);
+	if (ret)
+		return ret;
+
+	priv->sdr_timing = SDMMC_CLKSEL_TIMING(timing[0], timing[1], div);
+
+	ret = of_property_read_u32_array(np,
+			"samsung,dw-mshc-ddr-timing", timing, 2);
+	if (ret)
+		return ret;
+
+	priv->ddr_timing = SDMMC_CLKSEL_TIMING(timing[0], timing[1], div);
+	return 0;
+}
+
+static int dw_mci_exynos_setup_bus(struct dw_mci *host,
+				struct device_node *slot_np, u8 bus_width)
+{
+	int idx, gpio, ret;
+
+	if (!slot_np)
+		return -EINVAL;
+
+	/* cmd + clock + bus-width pins */
+	for (idx = 0; idx < NUM_PINS(bus_width); idx++) {
+		gpio = of_get_gpio(slot_np, idx);
+		if (!gpio_is_valid(gpio)) {
+			dev_err(host->dev, "invalid gpio: %d\n", gpio);
+			return -EINVAL;
+		}
+
+		ret = devm_gpio_request(host->dev, gpio, "dw-mci-bus");
+		if (ret) {
+			dev_err(host->dev, "gpio [%d] request failed\n", gpio);
+			return -EBUSY;
+		}
+	}
+
+	gpio = of_get_named_gpio(slot_np, "wp-gpios", 0);
+	if (gpio_is_valid(gpio)) {
+		if (devm_gpio_request(host->dev, gpio, "dw-mci-wp"))
+			dev_info(host->dev, "gpio [%d] request failed\n",
+						gpio);
+	} else {
+		dev_info(host->dev, "wp gpio not available");
+		host->pdata->quirks |= DW_MCI_QUIRK_NO_WRITE_PROTECT;
+	}
+
+	if (host->pdata->quirks & DW_MCI_QUIRK_BROKEN_CARD_DETECTION)
+		return 0;
+
+	gpio = of_get_named_gpio(slot_np, "samsung,cd-pinmux-gpio", 0);
+	if (gpio_is_valid(gpio)) {
+		if (devm_gpio_request(host->dev, gpio, "dw-mci-cd"))
+			dev_err(host->dev, "gpio [%d] request failed\n", gpio);
+	} else {
+		dev_info(host->dev, "cd gpio not available");
+	}
+
+	return 0;
+}
+
+/* Exynos5250 controller specific capabilities */
+static unsigned long exynos5250_dwmmc_caps[4] = {
+	MMC_CAP_UHS_DDR50 | MMC_CAP_1_8V_DDR |
+		MMC_CAP_8_BIT_DATA | MMC_CAP_CMD23,
+	MMC_CAP_CMD23,
+	MMC_CAP_CMD23,
+	MMC_CAP_CMD23,
+};
+
+static struct dw_mci_drv_data exynos5250_drv_data = {
+	.caps			= exynos5250_dwmmc_caps,
+	.init			= dw_mci_exynos_priv_init,
+	.setup_clock		= dw_mci_exynos_setup_clock,
+	.prepare_command	= dw_mci_exynos_prepare_command,
+	.set_ios		= dw_mci_exynos_set_ios,
+	.parse_dt		= dw_mci_exynos_parse_dt,
+	.setup_bus		= dw_mci_exynos_setup_bus,
+};
+
+static const struct of_device_id dw_mci_exynos_match[] = {
+	{ .compatible = "samsung,exynos5250-dw-mshc",
+			.data = (void *)&exynos5250_drv_data, },
+	{},
+};
+MODULE_DEVICE_TABLE(of, dw_mci_pltfm_match);
+
+int dw_mci_exynos_probe(struct platform_device *pdev)
+{
+	struct dw_mci_drv_data *drv_data;
+	const struct of_device_id *match;
+
+	match = of_match_node(dw_mci_exynos_match, pdev->dev.of_node);
+	drv_data = match->data;
+	return dw_mci_pltfm_register(pdev, drv_data);
+}
+
+static struct platform_driver dw_mci_exynos_pltfm_driver = {
+	.probe		= dw_mci_exynos_probe,
+	.remove		= __exit_p(dw_mci_pltfm_remove),
+	.driver		= {
+		.name		= "dwmmc_exynos",
+		.of_match_table	= of_match_ptr(dw_mci_exynos_match),
+		.pm		= &dw_mci_pltfm_pmops,
+	},
+};
+
+module_platform_driver(dw_mci_exynos_pltfm_driver);
+
+MODULE_DESCRIPTION("Samsung Specific DW-MSHC Driver Extension");
+MODULE_AUTHOR("Thomas Abraham <thomas.ab@samsung.com");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dwmmc-exynos");

include/linux/mmc/dw_mmc.h

@@ -227,7 +227,7 @@ struct dw_mci_board {
 	u32 num_slots;
 
 	u32 quirks; /* Workaround / Quirk flags */
-	unsigned int bus_hz; /* Bus speed */
+	unsigned int bus_hz; /* Clock speed at the cclk_in pad */
 
 	unsigned int caps;	/* Capabilities */
 	unsigned int caps2;	/* More capabilities */