mmc: sdhci-cadence: add Cadence SD4HC support

Add a driver for the Cadence SD4HC SD/SDIO/eMMC Controller.

For SD, it basically relies on the SDHCI standard code.
For eMMC, this driver provides some callbacks to support the
hardware part that is specific to this IP design.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

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

+* Cadence SD/SDIO/eMMC Host Controller
+
+Required properties:
+- compatible: should be "cdns,sd4hc".
+- reg: offset and length of the register set for the device.
+- interrupts: a single interrupt specifier.
+- clocks: phandle to the input clock.
+
+Optional properties:
+For eMMC configuration, supported speed modes are not indicated by the SDHCI
+Capabilities Register.  Instead, the following properties should be specified
+if supported.  See mmc.txt for details.
+- mmc-ddr-1_8v
+- mmc-ddr-1_2v
+- mmc-hs200-1_8v
+- mmc-hs200-1_2v
+- mmc-hs400-1_8v
+- mmc-hs400-1_2v
+
+Example:
+	emmc: sdhci@5a000000 {
+		compatible = "cdns,sd4hc";
+		reg = <0x5a000000 0x400>;
+		interrupts = <0 78 4>;
+		clocks = <&clk 4>;
+		bus-width = <8>;
+		mmc-ddr-1_8v;
+		mmc-hs200-1_8v;
+		mmc-hs400-1_8v;
+	};

drivers/mmc/host/Kconfig

@@ -165,6 +165,17 @@ config MMC_SDHCI_OF_HLWD
 
 	  If unsure, say N.
 
+config MMC_SDHCI_CADENCE
+	tristate "SDHCI support for the Cadence SD/SDIO/eMMC controller"
+	depends on MMC_SDHCI_PLTFM
+	depends on OF
+	help
+	  This selects the Cadence SD/SDIO/eMMC driver.
+
+	  If you have a controller with this interface, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_SDHCI_CNS3XXX
 	tristate "SDHCI support on the Cavium Networks CNS3xxx SoC"
 	depends on ARCH_CNS3XXX

drivers/mmc/host/Makefile

@@ -63,6 +63,7 @@ obj-$(CONFIG_MMC_REALTEK_PCI)	+= rtsx_pci_sdmmc.o
 obj-$(CONFIG_MMC_REALTEK_USB)	+= rtsx_usb_sdmmc.o
 
 obj-$(CONFIG_MMC_SDHCI_PLTFM)		+= sdhci-pltfm.o
+obj-$(CONFIG_MMC_SDHCI_CADENCE)		+= sdhci-cadence.o
 obj-$(CONFIG_MMC_SDHCI_CNS3XXX)		+= sdhci-cns3xxx.o
 obj-$(CONFIG_MMC_SDHCI_ESDHC_IMX)	+= sdhci-esdhc-imx.o
 obj-$(CONFIG_MMC_SDHCI_DOVE)		+= sdhci-dove.o

drivers/mmc/host/sdhci-cadence.c

+/*
+ * Copyright (C) 2016 Socionext Inc.
+ *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * 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.
+ *
+ * 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/bitops.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/mmc/host.h>
+
+#include "sdhci-pltfm.h"
+
+/* HRS - Host Register Set (specific to Cadence) */
+#define SDHCI_CDNS_HRS04		0x10		/* PHY access port */
+#define   SDHCI_CDNS_HRS04_ACK			BIT(26)
+#define   SDHCI_CDNS_HRS04_RD			BIT(25)
+#define   SDHCI_CDNS_HRS04_WR			BIT(24)
+#define   SDHCI_CDNS_HRS04_RDATA_SHIFT		12
+#define   SDHCI_CDNS_HRS04_WDATA_SHIFT		8
+#define   SDHCI_CDNS_HRS04_ADDR_SHIFT		0
+
+#define SDHCI_CDNS_HRS06		0x18		/* eMMC control */
+#define   SDHCI_CDNS_HRS06_TUNE_UP		BIT(15)
+#define   SDHCI_CDNS_HRS06_TUNE_SHIFT		8
+#define   SDHCI_CDNS_HRS06_TUNE_MASK		0x3f
+#define   SDHCI_CDNS_HRS06_MODE_MASK		0x7
+#define   SDHCI_CDNS_HRS06_MODE_SD		0x0
+#define   SDHCI_CDNS_HRS06_MODE_MMC_SDR		0x2
+#define   SDHCI_CDNS_HRS06_MODE_MMC_DDR		0x3
+#define   SDHCI_CDNS_HRS06_MODE_MMC_HS200	0x4
+#define   SDHCI_CDNS_HRS06_MODE_MMC_HS400	0x5
+
+/* SRS - Slot Register Set (SDHCI-compatible) */
+#define SDHCI_CDNS_SRS_BASE		0x200
+
+/* PHY */
+#define SDHCI_CDNS_PHY_DLY_SD_HS	0x00
+#define SDHCI_CDNS_PHY_DLY_SD_DEFAULT	0x01
+#define SDHCI_CDNS_PHY_DLY_UHS_SDR12	0x02
+#define SDHCI_CDNS_PHY_DLY_UHS_SDR25	0x03
+#define SDHCI_CDNS_PHY_DLY_UHS_SDR50	0x04
+#define SDHCI_CDNS_PHY_DLY_UHS_DDR50	0x05
+#define SDHCI_CDNS_PHY_DLY_EMMC_LEGACY	0x06
+#define SDHCI_CDNS_PHY_DLY_EMMC_SDR	0x07
+#define SDHCI_CDNS_PHY_DLY_EMMC_DDR	0x08
+
+/*
+ * The tuned val register is 6 bit-wide, but not the whole of the range is
+ * available.  The range 0-42 seems to be available (then 43 wraps around to 0)
+ * but I am not quite sure if it is official.  Use only 0 to 39 for safety.
+ */
+#define SDHCI_CDNS_MAX_TUNING_LOOP	40
+
+struct sdhci_cdns_priv {
+	void __iomem *hrs_addr;
+};
+
+static void sdhci_cdns_write_phy_reg(struct sdhci_cdns_priv *priv,
+				     u8 addr, u8 data)
+{
+	void __iomem *reg = priv->hrs_addr + SDHCI_CDNS_HRS04;
+	u32 tmp;
+
+	tmp = (data << SDHCI_CDNS_HRS04_WDATA_SHIFT) |
+	      (addr << SDHCI_CDNS_HRS04_ADDR_SHIFT);
+	writel(tmp, reg);
+
+	tmp |= SDHCI_CDNS_HRS04_WR;
+	writel(tmp, reg);
+
+	tmp &= ~SDHCI_CDNS_HRS04_WR;
+	writel(tmp, reg);
+}
+
+static void sdhci_cdns_phy_init(struct sdhci_cdns_priv *priv)
+{
+	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_SD_HS, 4);
+	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_SD_DEFAULT, 4);
+	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_LEGACY, 9);
+	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_SDR, 2);
+	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_DDR, 3);
+}
+
+static inline void *sdhci_cdns_priv(struct sdhci_host *host)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+
+	return sdhci_pltfm_priv(pltfm_host);
+}
+
+static unsigned int sdhci_cdns_get_timeout_clock(struct sdhci_host *host)
+{
+	/*
+	 * Cadence's spec says the Timeout Clock Frequency is the same as the
+	 * Base Clock Frequency.  Divide it by 1000 to return a value in kHz.
+	 */
+	return host->max_clk / 1000;
+}
+
+static void sdhci_cdns_set_uhs_signaling(struct sdhci_host *host,
+					 unsigned int timing)
+{
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+	u32 mode, tmp;
+
+	switch (timing) {
+	case MMC_TIMING_MMC_HS:
+		mode = SDHCI_CDNS_HRS06_MODE_MMC_SDR;
+		break;
+	case MMC_TIMING_MMC_DDR52:
+		mode = SDHCI_CDNS_HRS06_MODE_MMC_DDR;
+		break;
+	case MMC_TIMING_MMC_HS200:
+		mode = SDHCI_CDNS_HRS06_MODE_MMC_HS200;
+		break;
+	case MMC_TIMING_MMC_HS400:
+		mode = SDHCI_CDNS_HRS06_MODE_MMC_HS400;
+		break;
+	default:
+		mode = SDHCI_CDNS_HRS06_MODE_SD;
+		break;
+	}
+
+	/* The speed mode for eMMC is selected by HRS06 register */
+	tmp = readl(priv->hrs_addr + SDHCI_CDNS_HRS06);
+	tmp &= ~SDHCI_CDNS_HRS06_MODE_MASK;
+	tmp |= mode;
+	writel(tmp, priv->hrs_addr + SDHCI_CDNS_HRS06);
+
+	/* For SD, fall back to the default handler */
+	if (mode == SDHCI_CDNS_HRS06_MODE_SD)
+		sdhci_set_uhs_signaling(host, timing);
+}
+
+static const struct sdhci_ops sdhci_cdns_ops = {
+	.set_clock = sdhci_set_clock,
+	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
+	.set_bus_width = sdhci_set_bus_width,
+	.reset = sdhci_reset,
+	.set_uhs_signaling = sdhci_cdns_set_uhs_signaling,
+};
+
+static const struct sdhci_pltfm_data sdhci_cdns_pltfm_data = {
+	.ops = &sdhci_cdns_ops,
+};
+
+static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
+{
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+	void __iomem *reg = priv->hrs_addr + SDHCI_CDNS_HRS06;
+	u32 tmp;
+
+	if (WARN_ON(val > SDHCI_CDNS_HRS06_TUNE_MASK))
+		return -EINVAL;
+
+	tmp = readl(reg);
+	tmp &= ~(SDHCI_CDNS_HRS06_TUNE_MASK << SDHCI_CDNS_HRS06_TUNE_SHIFT);
+	tmp |= val << SDHCI_CDNS_HRS06_TUNE_SHIFT;
+	tmp |= SDHCI_CDNS_HRS06_TUNE_UP;
+	writel(tmp, reg);
+
+	return readl_poll_timeout(reg, tmp, !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
+				  0, 1);
+}
+
+static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	int cur_streak = 0;
+	int max_streak = 0;
+	int end_of_streak = 0;
+	int i;
+
+	/*
+	 * This handler only implements the eMMC tuning that is specific to
+	 * this controller.  Fall back to the standard method for SD timing.
+	 */
+	if (host->timing != MMC_TIMING_MMC_HS200)
+		return sdhci_execute_tuning(mmc, opcode);
+
+	if (WARN_ON(opcode != MMC_SEND_TUNING_BLOCK_HS200))
+		return -EINVAL;
+
+	for (i = 0; i < SDHCI_CDNS_MAX_TUNING_LOOP; i++) {
+		if (sdhci_cdns_set_tune_val(host, i) ||
+		    mmc_send_tuning(host->mmc, opcode, NULL)) { /* bad */
+			cur_streak = 0;
+		} else { /* good */
+			cur_streak++;
+			if (cur_streak > max_streak) {
+				max_streak = cur_streak;
+				end_of_streak = i;
+			}
+		}
+	}
+
+	if (!max_streak) {
+		dev_err(mmc_dev(host->mmc), "no tuning point found\n");
+		return -EIO;
+	}
+
+	return sdhci_cdns_set_tune_val(host, end_of_streak - max_streak / 2);
+}
+
+static int sdhci_cdns_probe(struct platform_device *pdev)
+{
+	struct sdhci_host *host;
+	struct sdhci_pltfm_host *pltfm_host;
+	struct sdhci_cdns_priv *priv;
+	struct clk *clk;
+	int ret;
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		return ret;
+
+	host = sdhci_pltfm_init(pdev, &sdhci_cdns_pltfm_data, sizeof(*priv));
+	if (IS_ERR(host)) {
+		ret = PTR_ERR(host);
+		goto disable_clk;
+	}
+
+	pltfm_host = sdhci_priv(host);
+	pltfm_host->clk = clk;
+
+	priv = sdhci_cdns_priv(host);
+	priv->hrs_addr = host->ioaddr;
+	host->ioaddr += SDHCI_CDNS_SRS_BASE;
+	host->mmc_host_ops.execute_tuning = sdhci_cdns_execute_tuning;
+
+	ret = mmc_of_parse(host->mmc);
+	if (ret)
+		goto free;
+
+	sdhci_cdns_phy_init(priv);
+
+	ret = sdhci_add_host(host);
+	if (ret)
+		goto free;
+
+	return 0;
+free:
+	sdhci_pltfm_free(pdev);
+disable_clk:
+	clk_disable_unprepare(clk);
+
+	return ret;
+}
+
+static const struct of_device_id sdhci_cdns_match[] = {
+	{ .compatible = "cdns,sd4hc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sdhci_cdns_match);
+
+static struct platform_driver sdhci_cdns_driver = {
+	.driver = {
+		.name = "sdhci-cdns",
+		.pm = &sdhci_pltfm_pmops,
+		.of_match_table = sdhci_cdns_match,
+	},
+	.probe = sdhci_cdns_probe,
+	.remove = sdhci_pltfm_unregister,
+};
+module_platform_driver(sdhci_cdns_driver);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
+MODULE_DESCRIPTION("Cadence SD/SDIO/eMMC Host Controller Driver");
+MODULE_LICENSE("GPL");