MMC: meson: initial support for GX platforms

Initial support for the SD/eMMC controller in the Amlogic S905/GX*
family of SoCs.

Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

MAINTAINERS

@@ -1043,6 +1043,7 @@ F:	arch/arm/mach-meson/
 F:	arch/arm/boot/dts/meson*
 F:	arch/arm64/boot/dts/amlogic/
 F: 	drivers/pinctrl/meson/
+F:	drivers/mmc/host/meson*
 N:	meson
 
 ARM/Annapurna Labs ALPINE ARCHITECTURE

drivers/mmc/host/Kconfig

@@ -322,6 +322,16 @@ config MMC_SDHCI_IPROC
 
 	  If unsure, say N.
 
+config MMC_MESON_GX
+	tristate "Amlogic S905/GX* SD/MMC Host Controller support"
+	depends on ARCH_MESON && MMC
+	help
+	  This selects support for the Amlogic SD/MMC Host Controller
+	  found on the S905/GX* family of SoCs.  This controller is
+	  MMC 5.1 compliant and supports SD, eMMC and SDIO interfaces.
+
+	  If you have a controller with this interface, say Y here.
+
 config MMC_MOXART
 	tristate "MOXART SD/MMC Host Controller support"
 	depends on ARCH_MOXART && MMC

drivers/mmc/host/Makefile

@@ -53,6 +53,7 @@ obj-$(CONFIG_MMC_JZ4740)	+= jz4740_mmc.o
 obj-$(CONFIG_MMC_VUB300)	+= vub300.o
 obj-$(CONFIG_MMC_USHC)		+= ushc.o
 obj-$(CONFIG_MMC_WMT)		+= wmt-sdmmc.o
+obj-$(CONFIG_MMC_MESON_GX)	+= meson-gx-mmc.o
 obj-$(CONFIG_MMC_MOXART)	+= moxart-mmc.o
 obj-$(CONFIG_MMC_SUNXI)		+= sunxi-mmc.o
 obj-$(CONFIG_MMC_USDHI6ROL0)	+= usdhi6rol0.o

drivers/mmc/host/meson-gx-mmc.c

@@ -0,0 +1,851 @@
+/*
+ * Amlogic SD/eMMC driver for the GX/S905 family SoCs
+ *
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Kevin Hilman <khilman@baylibre.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ * The full GNU General Public License is included in this distribution
+ * in the file called COPYING.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/ioport.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>
+#include <linux/mmc/sdio.h>
+#include <linux/mmc/slot-gpio.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/regulator/consumer.h>
+
+#define DRIVER_NAME "meson-gx-mmc"
+
+#define SD_EMMC_CLOCK 0x0
+#define   CLK_DIV_SHIFT 0
+#define   CLK_DIV_WIDTH 6
+#define   CLK_DIV_MASK 0x3f
+#define   CLK_DIV_MAX 63
+#define   CLK_SRC_SHIFT 6
+#define   CLK_SRC_WIDTH 2
+#define   CLK_SRC_MASK 0x3
+#define   CLK_SRC_XTAL 0   /* external crystal */
+#define   CLK_SRC_XTAL_RATE 24000000
+#define   CLK_SRC_PLL 1    /* FCLK_DIV2 */
+#define   CLK_SRC_PLL_RATE 1000000000
+#define   CLK_PHASE_SHIFT 8
+#define   CLK_PHASE_MASK 0x3
+#define   CLK_PHASE_0 0
+#define   CLK_PHASE_90 1
+#define   CLK_PHASE_180 2
+#define   CLK_PHASE_270 3
+#define   CLK_ALWAYS_ON BIT(24)
+
+#define SD_EMMC_DElAY 0x4
+#define SD_EMMC_ADJUST 0x8
+#define SD_EMMC_CALOUT 0x10
+#define SD_EMMC_START 0x40
+#define   START_DESC_INIT BIT(0)
+#define   START_DESC_BUSY BIT(1)
+#define   START_DESC_ADDR_SHIFT 2
+#define   START_DESC_ADDR_MASK (~0x3)
+
+#define SD_EMMC_CFG 0x44
+#define   CFG_BUS_WIDTH_SHIFT 0
+#define   CFG_BUS_WIDTH_MASK 0x3
+#define   CFG_BUS_WIDTH_1 0x0
+#define   CFG_BUS_WIDTH_4 0x1
+#define   CFG_BUS_WIDTH_8 0x2
+#define   CFG_DDR BIT(2)
+#define   CFG_BLK_LEN_SHIFT 4
+#define   CFG_BLK_LEN_MASK 0xf
+#define   CFG_RESP_TIMEOUT_SHIFT 8
+#define   CFG_RESP_TIMEOUT_MASK 0xf
+#define   CFG_RC_CC_SHIFT 12
+#define   CFG_RC_CC_MASK 0xf
+#define   CFG_STOP_CLOCK BIT(22)
+#define   CFG_CLK_ALWAYS_ON BIT(18)
+#define   CFG_AUTO_CLK BIT(23)
+
+#define SD_EMMC_STATUS 0x48
+#define   STATUS_BUSY BIT(31)
+
+#define SD_EMMC_IRQ_EN 0x4c
+#define   IRQ_EN_MASK 0x3fff
+#define   IRQ_RXD_ERR_SHIFT 0
+#define   IRQ_RXD_ERR_MASK 0xff
+#define   IRQ_TXD_ERR BIT(8)
+#define   IRQ_DESC_ERR BIT(9)
+#define   IRQ_RESP_ERR BIT(10)
+#define   IRQ_RESP_TIMEOUT BIT(11)
+#define   IRQ_DESC_TIMEOUT BIT(12)
+#define   IRQ_END_OF_CHAIN BIT(13)
+#define   IRQ_RESP_STATUS BIT(14)
+#define   IRQ_SDIO BIT(15)
+
+#define SD_EMMC_CMD_CFG 0x50
+#define SD_EMMC_CMD_ARG 0x54
+#define SD_EMMC_CMD_DAT 0x58
+#define SD_EMMC_CMD_RSP 0x5c
+#define SD_EMMC_CMD_RSP1 0x60
+#define SD_EMMC_CMD_RSP2 0x64
+#define SD_EMMC_CMD_RSP3 0x68
+
+#define SD_EMMC_RXD 0x94
+#define SD_EMMC_TXD 0x94
+#define SD_EMMC_LAST_REG SD_EMMC_TXD
+
+#define SD_EMMC_CFG_BLK_SIZE 512 /* internal buffer max: 512 bytes */
+#define SD_EMMC_CFG_RESP_TIMEOUT 256 /* in clock cycles */
+#define SD_EMMC_CFG_CMD_GAP 16 /* in clock cycles */
+#define MUX_CLK_NUM_PARENTS 2
+
+struct meson_host {
+	struct	device		*dev;
+	struct	mmc_host	*mmc;
+	struct	mmc_request	*mrq;
+	struct	mmc_command	*cmd;
+
+	spinlock_t lock;
+	void __iomem *regs;
+	int irq;
+	u32 ocr_mask;
+	struct clk *core_clk;
+	struct clk_mux mux;
+	struct clk *mux_clk;
+	struct clk *mux_parent[MUX_CLK_NUM_PARENTS];
+	unsigned long mux_parent_rate[MUX_CLK_NUM_PARENTS];
+
+	struct clk_divider cfg_div;
+	struct clk *cfg_div_clk;
+
+	unsigned int bounce_buf_size;
+	void *bounce_buf;
+	dma_addr_t bounce_dma_addr;
+
+	bool vqmmc_enabled;
+};
+
+struct sd_emmc_desc {
+	u32 cmd_cfg;
+	u32 cmd_arg;
+	u32 cmd_data;
+	u32 cmd_resp;
+};
+#define CMD_CFG_LENGTH_SHIFT 0
+#define CMD_CFG_LENGTH_MASK 0x1ff
+#define CMD_CFG_BLOCK_MODE BIT(9)
+#define CMD_CFG_R1B BIT(10)
+#define CMD_CFG_END_OF_CHAIN BIT(11)
+#define CMD_CFG_TIMEOUT_SHIFT 12
+#define CMD_CFG_TIMEOUT_MASK 0xf
+#define CMD_CFG_NO_RESP BIT(16)
+#define CMD_CFG_NO_CMD BIT(17)
+#define CMD_CFG_DATA_IO BIT(18)
+#define CMD_CFG_DATA_WR BIT(19)
+#define CMD_CFG_RESP_NOCRC BIT(20)
+#define CMD_CFG_RESP_128 BIT(21)
+#define CMD_CFG_RESP_NUM BIT(22)
+#define CMD_CFG_DATA_NUM BIT(23)
+#define CMD_CFG_CMD_INDEX_SHIFT 24
+#define CMD_CFG_CMD_INDEX_MASK 0x3f
+#define CMD_CFG_ERROR BIT(30)
+#define CMD_CFG_OWNER BIT(31)
+
+#define CMD_DATA_MASK (~0x3)
+#define CMD_DATA_BIG_ENDIAN BIT(1)
+#define CMD_DATA_SRAM BIT(0)
+#define CMD_RESP_MASK (~0x1)
+#define CMD_RESP_SRAM BIT(0)
+
+static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
+{
+	struct mmc_host *mmc = host->mmc;
+	int ret = 0;
+	u32 cfg;
+
+	if (clk_rate) {
+		if (WARN_ON(clk_rate > mmc->f_max))
+			clk_rate = mmc->f_max;
+		else if (WARN_ON(clk_rate < mmc->f_min))
+			clk_rate = mmc->f_min;
+	}
+
+	if (clk_rate == mmc->actual_clock)
+		return 0;
+
+	/* stop clock */
+	cfg = readl(host->regs + SD_EMMC_CFG);
+	if (!(cfg & CFG_STOP_CLOCK)) {
+		cfg |= CFG_STOP_CLOCK;
+		writel(cfg, host->regs + SD_EMMC_CFG);
+	}
+
+	dev_dbg(host->dev, "change clock rate %u -> %lu\n",
+		mmc->actual_clock, clk_rate);
+
+	if (clk_rate == 0) {
+		mmc->actual_clock = 0;
+		return 0;
+	}
+
+	ret = clk_set_rate(host->cfg_div_clk, clk_rate);
+	if (ret)
+		dev_warn(host->dev, "Unable to set cfg_div_clk to %lu. ret=%d\n",
+			 clk_rate, ret);
+	else if (clk_rate && clk_rate != clk_get_rate(host->cfg_div_clk))
+		dev_warn(host->dev, "divider requested rate %lu != actual rate %lu: ret=%d\n",
+			 clk_rate, clk_get_rate(host->cfg_div_clk), ret);
+	else
+		mmc->actual_clock = clk_rate;
+
+	/* (re)start clock, if non-zero */
+	if (!ret && clk_rate) {
+		cfg = readl(host->regs + SD_EMMC_CFG);
+		cfg &= ~CFG_STOP_CLOCK;
+		writel(cfg, host->regs + SD_EMMC_CFG);
+	}
+
+	return ret;
+}
+
+/*
+ * The SD/eMMC IP block has an internal mux and divider used for
+ * generating the MMC clock.  Use the clock framework to create and
+ * manage these clocks.
+ */
+static int meson_mmc_clk_init(struct meson_host *host)
+{
+	struct clk_init_data init;
+	char clk_name[32];
+	int i, ret = 0;
+	const char *mux_parent_names[MUX_CLK_NUM_PARENTS];
+	unsigned int mux_parent_count = 0;
+	const char *clk_div_parents[1];
+	unsigned int f_min = UINT_MAX;
+	u32 clk_reg, cfg;
+
+	/* get the mux parents */
+	for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) {
+		char name[16];
+
+		snprintf(name, sizeof(name), "clkin%d", i);
+		host->mux_parent[i] = devm_clk_get(host->dev, name);
+		if (IS_ERR(host->mux_parent[i])) {
+			ret = PTR_ERR(host->mux_parent[i]);
+			if (PTR_ERR(host->mux_parent[i]) != -EPROBE_DEFER)
+				dev_err(host->dev, "Missing clock %s\n", name);
+			host->mux_parent[i] = NULL;
+			return ret;
+		}
+
+		host->mux_parent_rate[i] = clk_get_rate(host->mux_parent[i]);
+		mux_parent_names[i] = __clk_get_name(host->mux_parent[i]);
+		mux_parent_count++;
+		if (host->mux_parent_rate[i] < f_min)
+			f_min = host->mux_parent_rate[i];
+	}
+
+	/* cacluate f_min based on input clocks, and max divider value */
+	if (f_min != UINT_MAX)
+		f_min = DIV_ROUND_UP(CLK_SRC_XTAL_RATE, CLK_DIV_MAX);
+	else
+		f_min = 4000000;  /* default min: 400 MHz */
+	host->mmc->f_min = f_min;
+
+	/* create the mux */
+	snprintf(clk_name, sizeof(clk_name), "%s#mux", dev_name(host->dev));
+	init.name = clk_name;
+	init.ops = &clk_mux_ops;
+	init.flags = 0;
+	init.parent_names = mux_parent_names;
+	init.num_parents = mux_parent_count;
+
+	host->mux.reg = host->regs + SD_EMMC_CLOCK;
+	host->mux.shift = CLK_SRC_SHIFT;
+	host->mux.mask = CLK_SRC_MASK;
+	host->mux.flags = 0;
+	host->mux.table = NULL;
+	host->mux.hw.init = &init;
+
+	host->mux_clk = devm_clk_register(host->dev, &host->mux.hw);
+	if (WARN_ON(IS_ERR(host->mux_clk)))
+		return PTR_ERR(host->mux_clk);
+
+	/* create the divider */
+	snprintf(clk_name, sizeof(clk_name), "%s#div", dev_name(host->dev));
+	init.name = devm_kstrdup(host->dev, clk_name, GFP_KERNEL);
+	init.ops = &clk_divider_ops;
+	init.flags = CLK_SET_RATE_PARENT;
+	clk_div_parents[0] = __clk_get_name(host->mux_clk);
+	init.parent_names = clk_div_parents;
+	init.num_parents = ARRAY_SIZE(clk_div_parents);
+
+	host->cfg_div.reg = host->regs + SD_EMMC_CLOCK;
+	host->cfg_div.shift = CLK_DIV_SHIFT;
+	host->cfg_div.width = CLK_DIV_WIDTH;
+	host->cfg_div.hw.init = &init;
+	host->cfg_div.flags = CLK_DIVIDER_ONE_BASED |
+		CLK_DIVIDER_ROUND_CLOSEST | CLK_DIVIDER_ALLOW_ZERO;
+
+	host->cfg_div_clk = devm_clk_register(host->dev, &host->cfg_div.hw);
+	if (WARN_ON(PTR_ERR_OR_ZERO(host->cfg_div_clk)))
+		return PTR_ERR(host->cfg_div_clk);
+
+	/* init SD_EMMC_CLOCK to sane defaults w/min clock rate */
+	clk_reg = 0;
+	clk_reg |= CLK_PHASE_180 << CLK_PHASE_SHIFT;
+	clk_reg |= CLK_SRC_XTAL << CLK_SRC_SHIFT;
+	clk_reg |= CLK_DIV_MAX << CLK_DIV_SHIFT;
+	clk_reg &= ~CLK_ALWAYS_ON;
+	writel(clk_reg, host->regs + SD_EMMC_CLOCK);
+
+	/* Ensure clock starts in "auto" mode, not "always on" */
+	cfg = readl(host->regs + SD_EMMC_CFG);
+	cfg &= ~CFG_CLK_ALWAYS_ON;
+	cfg |= CFG_AUTO_CLK;
+	writel(cfg, host->regs + SD_EMMC_CFG);
+
+	ret = clk_prepare_enable(host->cfg_div_clk);
+	if (!ret)
+		ret = meson_mmc_clk_set(host, f_min);
+
+	if (!ret)
+		clk_disable_unprepare(host->cfg_div_clk);
+
+	return ret;
+}
+
+static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	struct meson_host *host = mmc_priv(mmc);
+	u32 bus_width;
+	u32 val, orig;
+
+	/*
+	 * GPIO regulator, only controls switching between 1v8 and
+	 * 3v3, doesn't support MMC_POWER_OFF, MMC_POWER_ON.
+	 */
+	switch (ios->power_mode) {
+	case MMC_POWER_OFF:
+		if (!IS_ERR(mmc->supply.vmmc))
+			mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
+
+		if (!IS_ERR(mmc->supply.vqmmc) && host->vqmmc_enabled) {
+			regulator_disable(mmc->supply.vqmmc);
+			host->vqmmc_enabled = false;
+		}
+
+		break;
+
+	case MMC_POWER_UP:
+		if (!IS_ERR(mmc->supply.vmmc))
+			mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, ios->vdd);
+		break;
+
+	case MMC_POWER_ON:
+		if (!IS_ERR(mmc->supply.vqmmc) && !host->vqmmc_enabled) {
+			int ret = regulator_enable(mmc->supply.vqmmc);
+
+			if (ret < 0)
+				dev_err(mmc_dev(mmc),
+					"failed to enable vqmmc regulator\n");
+			else
+				host->vqmmc_enabled = true;
+		}
+
+		break;
+	}
+
+
+	meson_mmc_clk_set(host, ios->clock);
+
+	/* Bus width */
+	val = readl(host->regs + SD_EMMC_CFG);
+	switch (ios->bus_width) {
+	case MMC_BUS_WIDTH_1:
+		bus_width = CFG_BUS_WIDTH_1;
+		break;
+	case MMC_BUS_WIDTH_4:
+		bus_width = CFG_BUS_WIDTH_4;
+		break;
+	case MMC_BUS_WIDTH_8:
+		bus_width = CFG_BUS_WIDTH_8;
+		break;
+	default:
+		dev_err(host->dev, "Invalid ios->bus_width: %u.  Setting to 4.\n",
+			ios->bus_width);
+		bus_width = CFG_BUS_WIDTH_4;
+		return;
+	}
+
+	val = readl(host->regs + SD_EMMC_CFG);
+	orig = val;
+
+	val &= ~(CFG_BUS_WIDTH_MASK << CFG_BUS_WIDTH_SHIFT);
+	val |= bus_width << CFG_BUS_WIDTH_SHIFT;
+
+	val &= ~(CFG_BLK_LEN_MASK << CFG_BLK_LEN_SHIFT);
+	val |= ilog2(SD_EMMC_CFG_BLK_SIZE) << CFG_BLK_LEN_SHIFT;
+
+	val &= ~(CFG_RESP_TIMEOUT_MASK << CFG_RESP_TIMEOUT_SHIFT);
+	val |= ilog2(SD_EMMC_CFG_RESP_TIMEOUT) << CFG_RESP_TIMEOUT_SHIFT;
+
+	val &= ~(CFG_RC_CC_MASK << CFG_RC_CC_SHIFT);
+	val |= ilog2(SD_EMMC_CFG_CMD_GAP) << CFG_RC_CC_SHIFT;
+
+	writel(val, host->regs + SD_EMMC_CFG);
+
+	if (val != orig)
+		dev_dbg(host->dev, "%s: SD_EMMC_CFG: 0x%08x -> 0x%08x\n",
+			__func__, orig, val);
+}
+
+static int meson_mmc_request_done(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct meson_host *host = mmc_priv(mmc);
+
+	WARN_ON(host->mrq != mrq);
+
+	host->mrq = NULL;
+	host->cmd = NULL;
+	mmc_request_done(host->mmc, mrq);
+
+	return 0;
+}
+
+static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
+{
+	struct meson_host *host = mmc_priv(mmc);
+	struct sd_emmc_desc *desc, desc_tmp;
+	u32 cfg;
+	u8 blk_len, cmd_cfg_timeout;
+	unsigned int xfer_bytes = 0;
+
+	/* Setup descriptors */
+	dma_rmb();
+	desc = &desc_tmp;
+	memset(desc, 0, sizeof(struct sd_emmc_desc));
+
+	desc->cmd_cfg |= (cmd->opcode & CMD_CFG_CMD_INDEX_MASK)	<<
+		CMD_CFG_CMD_INDEX_SHIFT;
+	desc->cmd_cfg |= CMD_CFG_OWNER;  /* owned by CPU */
+	desc->cmd_arg = cmd->arg;
+
+	/* Response */
+	if (cmd->flags & MMC_RSP_PRESENT) {
+		desc->cmd_cfg &= ~CMD_CFG_NO_RESP;
+		if (cmd->flags & MMC_RSP_136)
+			desc->cmd_cfg |= CMD_CFG_RESP_128;
+		desc->cmd_cfg |= CMD_CFG_RESP_NUM;
+		desc->cmd_resp = 0;
+
+		if (!(cmd->flags & MMC_RSP_CRC))
+			desc->cmd_cfg |= CMD_CFG_RESP_NOCRC;
+
+		if (cmd->flags & MMC_RSP_BUSY)
+			desc->cmd_cfg |= CMD_CFG_R1B;
+	} else {
+		desc->cmd_cfg |= CMD_CFG_NO_RESP;
+	}
+
+	/* data? */
+	if (cmd->data) {
+		desc->cmd_cfg |= CMD_CFG_DATA_IO;
+		if (cmd->data->blocks > 1) {
+			desc->cmd_cfg |= CMD_CFG_BLOCK_MODE;
+			desc->cmd_cfg |=
+				(cmd->data->blocks & CMD_CFG_LENGTH_MASK) <<
+				CMD_CFG_LENGTH_SHIFT;
+
+			/* check if block-size matches, if not update */
+			cfg = readl(host->regs + SD_EMMC_CFG);
+			blk_len = cfg & (CFG_BLK_LEN_MASK << CFG_BLK_LEN_SHIFT);
+			blk_len >>= CFG_BLK_LEN_SHIFT;
+			if (blk_len != ilog2(cmd->data->blksz)) {
+				dev_warn(host->dev, "%s: update blk_len %d -> %d\n",
+					__func__, blk_len,
+					 ilog2(cmd->data->blksz));
+				blk_len = ilog2(cmd->data->blksz);
+				cfg &= ~(CFG_BLK_LEN_MASK << CFG_BLK_LEN_SHIFT);
+				cfg |= blk_len << CFG_BLK_LEN_SHIFT;
+				writel(cfg, host->regs + SD_EMMC_CFG);
+			}
+		} else {
+			desc->cmd_cfg &= ~CMD_CFG_BLOCK_MODE;
+			desc->cmd_cfg |=
+				(cmd->data->blksz & CMD_CFG_LENGTH_MASK) <<
+				CMD_CFG_LENGTH_SHIFT;
+		}
+
+		cmd->data->bytes_xfered = 0;
+		xfer_bytes = cmd->data->blksz * cmd->data->blocks;
+		if (cmd->data->flags & MMC_DATA_WRITE) {
+			desc->cmd_cfg |= CMD_CFG_DATA_WR;
+			WARN_ON(xfer_bytes > host->bounce_buf_size);
+			sg_copy_to_buffer(cmd->data->sg, cmd->data->sg_len,
+					  host->bounce_buf, xfer_bytes);
+			cmd->data->bytes_xfered = xfer_bytes;
+			dma_wmb();
+		} else {
+			desc->cmd_cfg &= ~CMD_CFG_DATA_WR;
+		}
+
+		if (xfer_bytes > 0) {
+			desc->cmd_cfg &= ~CMD_CFG_DATA_NUM;
+			desc->cmd_data = host->bounce_dma_addr & CMD_DATA_MASK;
+		} else {
+			/* write data to data_addr */
+			desc->cmd_cfg |= CMD_CFG_DATA_NUM;
+			desc->cmd_data = 0;
+		}
+
+		cmd_cfg_timeout = 12;
+	} else {
+		desc->cmd_cfg &= ~CMD_CFG_DATA_IO;
+		cmd_cfg_timeout = 10;
+	}
+	desc->cmd_cfg |= (cmd_cfg_timeout & CMD_CFG_TIMEOUT_MASK) <<
+		CMD_CFG_TIMEOUT_SHIFT;
+
+	host->cmd = cmd;
+
+	/* Last descriptor */
+	desc->cmd_cfg |= CMD_CFG_END_OF_CHAIN;
+	writel(desc->cmd_cfg, host->regs + SD_EMMC_CMD_CFG);
+	writel(desc->cmd_data, host->regs + SD_EMMC_CMD_DAT);
+	writel(desc->cmd_resp, host->regs + SD_EMMC_CMD_RSP);
+	wmb(); /* ensure descriptor is written before kicked */
+	writel(desc->cmd_arg, host->regs + SD_EMMC_CMD_ARG);
+}
+
+static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct meson_host *host = mmc_priv(mmc);
+
+	WARN_ON(host->mrq != NULL);
+
+	/* Stop execution */
+	writel(0, host->regs + SD_EMMC_START);
+
+	/* clear, ack, enable all interrupts */
+	writel(0, host->regs + SD_EMMC_IRQ_EN);
+	writel(IRQ_EN_MASK, host->regs + SD_EMMC_STATUS);
+	writel(IRQ_EN_MASK, host->regs + SD_EMMC_IRQ_EN);
+
+	host->mrq = mrq;
+
+	if (mrq->sbc)
+		meson_mmc_start_cmd(mmc, mrq->sbc);
+	else
+		meson_mmc_start_cmd(mmc, mrq->cmd);
+}
+
+static int meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
+{
+	struct meson_host *host = mmc_priv(mmc);
+
+	if (cmd->flags & MMC_RSP_136) {
+		cmd->resp[0] = readl(host->regs + SD_EMMC_CMD_RSP3);
+		cmd->resp[1] = readl(host->regs + SD_EMMC_CMD_RSP2);
+		cmd->resp[2] = readl(host->regs + SD_EMMC_CMD_RSP1);
+		cmd->resp[3] = readl(host->regs + SD_EMMC_CMD_RSP);
+	} else if (cmd->flags & MMC_RSP_PRESENT) {
+		cmd->resp[0] = readl(host->regs + SD_EMMC_CMD_RSP);
+	}
+
+	return 0;
+}
+
+static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
+{
+	struct meson_host *host = dev_id;
+	struct mmc_request *mrq;
+	struct mmc_command *cmd = host->cmd;
+	u32 irq_en, status, raw_status;
+	irqreturn_t ret = IRQ_HANDLED;
+
+	if (WARN_ON(!host))
+		return IRQ_NONE;
+
+	mrq = host->mrq;
+
+	if (WARN_ON(!mrq))
+		return IRQ_NONE;
+
+	if (WARN_ON(!cmd))
+		return IRQ_NONE;
+
+	spin_lock(&host->lock);
+	irq_en = readl(host->regs + SD_EMMC_IRQ_EN);
+	raw_status = readl(host->regs + SD_EMMC_STATUS);
+	status = raw_status & irq_en;
+
+	if (!status) {
+		dev_warn(host->dev, "Spurious IRQ! status=0x%08x, irq_en=0x%08x\n",
+			 raw_status, irq_en);
+		ret = IRQ_NONE;
+		goto out;
+	}
+
+	cmd->error = 0;
+	if (status & IRQ_RXD_ERR_MASK) {
+		dev_dbg(host->dev, "Unhandled IRQ: RXD error\n");
+		cmd->error = -EILSEQ;
+	}
+	if (status & IRQ_TXD_ERR) {
+		dev_dbg(host->dev, "Unhandled IRQ: TXD error\n");
+		cmd->error = -EILSEQ;
+	}
+	if (status & IRQ_DESC_ERR)
+		dev_dbg(host->dev, "Unhandled IRQ: Descriptor error\n");
+	if (status & IRQ_RESP_ERR) {
+		dev_dbg(host->dev, "Unhandled IRQ: Response error\n");
+		cmd->error = -EILSEQ;
+	}
+	if (status & IRQ_RESP_TIMEOUT) {
+		dev_dbg(host->dev, "Unhandled IRQ: Response timeout\n");
+		cmd->error = -ETIMEDOUT;
+	}
+	if (status & IRQ_DESC_TIMEOUT) {
+		dev_dbg(host->dev, "Unhandled IRQ: Descriptor timeout\n");
+		cmd->error = -ETIMEDOUT;
+	}
+	if (status & IRQ_SDIO)
+		dev_dbg(host->dev, "Unhandled IRQ: SDIO.\n");
+
+	if (status & (IRQ_END_OF_CHAIN | IRQ_RESP_STATUS))
+		ret = IRQ_WAKE_THREAD;
+	else  {
+		dev_warn(host->dev, "Unknown IRQ! status=0x%04x: MMC CMD%u arg=0x%08x flags=0x%08x stop=%d\n",
+			 status, cmd->opcode, cmd->arg,
+			 cmd->flags, mrq->stop ? 1 : 0);
+		if (cmd->data) {
+			struct mmc_data *data = cmd->data;
+
+			dev_warn(host->dev, "\tblksz %u blocks %u flags 0x%08x (%s%s)",
+				 data->blksz, data->blocks, data->flags,
+				 data->flags & MMC_DATA_WRITE ? "write" : "",
+				 data->flags & MMC_DATA_READ ? "read" : "");
+		}
+	}
+
+out:
+	/* ack all (enabled) interrupts */
+	writel(status, host->regs + SD_EMMC_STATUS);
+
+	if (ret == IRQ_HANDLED) {
+		meson_mmc_read_resp(host->mmc, cmd);
+		meson_mmc_request_done(host->mmc, cmd->mrq);
+	}
+
+	spin_unlock(&host->lock);
+	return ret;
+}
+
+static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
+{
+	struct meson_host *host = dev_id;
+	struct mmc_request *mrq = host->mrq;
+	struct mmc_command *cmd = host->cmd;
+	struct mmc_data *data;
+	unsigned int xfer_bytes;
+	int ret = IRQ_HANDLED;
+
+	if (WARN_ON(!mrq))
+		ret = IRQ_NONE;
+
+	if (WARN_ON(!cmd))
+		ret = IRQ_NONE;
+
+	data = cmd->data;
+	if (data) {
+		xfer_bytes = data->blksz * data->blocks;
+		if (data->flags & MMC_DATA_READ) {
+			WARN_ON(xfer_bytes > host->bounce_buf_size);
+			sg_copy_from_buffer(data->sg, data->sg_len,
+					    host->bounce_buf, xfer_bytes);
+			data->bytes_xfered = xfer_bytes;
+		}
+	}
+
+	meson_mmc_read_resp(host->mmc, cmd);
+	if (!data || !data->stop || mrq->sbc)
+		meson_mmc_request_done(host->mmc, mrq);
+	else
+		meson_mmc_start_cmd(host->mmc, data->stop);
+
+	return ret;
+}
+
+/*
+ * NOTE: we only need this until the GPIO/pinctrl driver can handle
+ * interrupts.  For now, the MMC core will use this for polling.
+ */
+static int meson_mmc_get_cd(struct mmc_host *mmc)
+{
+	int status = mmc_gpio_get_cd(mmc);
+
+	if (status == -ENOSYS)
+		return 1; /* assume present */
+
+	return status;
+}
+
+static const struct mmc_host_ops meson_mmc_ops = {
+	.request	= meson_mmc_request,
+	.set_ios	= meson_mmc_set_ios,
+	.get_cd         = meson_mmc_get_cd,
+};
+
+static int meson_mmc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct meson_host *host;
+	struct mmc_host *mmc;
+	int ret;
+
+	mmc = mmc_alloc_host(sizeof(struct meson_host), &pdev->dev);
+	if (!mmc)
+		return -ENOMEM;
+	host = mmc_priv(mmc);
+	host->mmc = mmc;
+	host->dev = &pdev->dev;
+	dev_set_drvdata(&pdev->dev, host);
+
+	spin_lock_init(&host->lock);
+
+	/* Get regulators and the supported OCR mask */
+	host->vqmmc_enabled = false;
+	ret = mmc_regulator_get_supply(mmc);
+	if (ret == -EPROBE_DEFER)
+		goto free_host;
+
+	ret = mmc_of_parse(mmc);
+	if (ret) {
+		dev_warn(&pdev->dev, "error parsing DT: %d\n", ret);
+		goto free_host;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	host->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(host->regs)) {
+		ret = PTR_ERR(host->regs);
+		goto free_host;
+	}
+
+	host->irq = platform_get_irq(pdev, 0);
+	if (host->irq == 0) {
+		dev_err(&pdev->dev, "failed to get interrupt resource.\n");
+		ret = -EINVAL;
+		goto free_host;
+	}
+
+	host->core_clk = devm_clk_get(&pdev->dev, "core");
+	if (IS_ERR(host->core_clk)) {
+		ret = PTR_ERR(host->core_clk);
+		goto free_host;
+	}
+
+	ret = clk_prepare_enable(host->core_clk);
+	if (ret)
+		goto free_host;
+
+	ret = meson_mmc_clk_init(host);
+	if (ret)
+		goto free_host;
+
+	/* Stop execution */
+	writel(0, host->regs + SD_EMMC_START);
+
+	/* clear, ack, enable all interrupts */
+	writel(0, host->regs + SD_EMMC_IRQ_EN);
+	writel(IRQ_EN_MASK, host->regs + SD_EMMC_STATUS);
+
+	ret = devm_request_threaded_irq(&pdev->dev, host->irq,
+					meson_mmc_irq, meson_mmc_irq_thread,
+					IRQF_SHARED, DRIVER_NAME, host);
+	if (ret)
+		goto free_host;
+
+	/* data bounce buffer */
+	host->bounce_buf_size = SZ_512K;
+	host->bounce_buf =
+		dma_alloc_coherent(host->dev, host->bounce_buf_size,
+				   &host->bounce_dma_addr, GFP_KERNEL);
+	if (host->bounce_buf == NULL) {
+		dev_err(host->dev, "Unable to map allocate DMA bounce buffer.\n");
+		ret = -ENOMEM;
+		goto free_host;
+	}
+
+	mmc->ops = &meson_mmc_ops;
+	mmc_add_host(mmc);
+
+	return 0;
+
+free_host:
+	clk_disable_unprepare(host->cfg_div_clk);
+	clk_disable_unprepare(host->core_clk);
+	mmc_free_host(mmc);
+	return ret;
+}
+
+static int meson_mmc_remove(struct platform_device *pdev)
+{
+	struct meson_host *host = dev_get_drvdata(&pdev->dev);
+
+	if (WARN_ON(!host))
+		return 0;
+
+	if (host->bounce_buf)
+		dma_free_coherent(host->dev, host->bounce_buf_size,
+				  host->bounce_buf, host->bounce_dma_addr);
+
+	clk_disable_unprepare(host->cfg_div_clk);
+	clk_disable_unprepare(host->core_clk);
+
+	mmc_free_host(host->mmc);
+	return 0;
+}
+
+static const struct of_device_id meson_mmc_of_match[] = {
+	{ .compatible = "amlogic,meson-gx-mmc", },
+	{ .compatible = "amlogic,meson-gxbb-mmc", },
+	{ .compatible = "amlogic,meson-gxl-mmc", },
+	{ .compatible = "amlogic,meson-gxm-mmc", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, meson_mmc_of_match);
+
+static struct platform_driver meson_mmc_driver = {
+	.probe		= meson_mmc_probe,
+	.remove		= meson_mmc_remove,
+	.driver		= {
+		.name = DRIVER_NAME,
+		.of_match_table = of_match_ptr(meson_mmc_of_match),
+	},
+};
+
+module_platform_driver(meson_mmc_driver);
+
+MODULE_DESCRIPTION("Amlogic S905*/GX* SD/eMMC driver");
+MODULE_AUTHOR("Kevin Hilman <khilman@baylibre.com>");
+MODULE_LICENSE("GPL v2");