[PATCH v2 1/4] mci: add driver for BCM283x sdhost core

[Lucas Stach <l.stach@pengutronix.de>]

The sdhost is a simple MMC controller found on the Broadcom
BCM283x line of SoCs. The driver code was ported from U-Boot
and then simplified a bit, by dropping a lot of the state
tracking.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
 drivers/mci/Kconfig          |   4 +
 drivers/mci/Makefile         |   1 +
 drivers/mci/bcm2835-sdhost.c | 638 +++++++++++++++++++++++++++++++++++
 3 files changed, 643 insertions(+)
 create mode 100644 drivers/mci/bcm2835-sdhost.c

diff --git a/drivers/mci/Kconfig b/drivers/mci/Kconfig
index 911cc0cb1e..08c8c84e8c 100644
--- a/drivers/mci/Kconfig
+++ b/drivers/mci/Kconfig
@@ -66,6 +66,10 @@ config MCI_BCM283X
 	bool "MCI support for BCM283X"
 	depends on ARCH_BCM283X
 
+config MCI_BCM283X_SDHOST
+	bool "BCM283X sdhost"
+	depends on ARCH_BCM283X
+
 config MCI_DOVE
 	bool "Marvell Dove SDHCI"
 	depends on ARCH_DOVE
diff --git a/drivers/mci/Makefile b/drivers/mci/Makefile
index f6214c0cbb..25a1d073dc 100644
--- a/drivers/mci/Makefile
+++ b/drivers/mci/Makefile
@@ -1,6 +1,7 @@
 obj-$(CONFIG_MCI)		+= mci-core.o
 obj-$(CONFIG_MCI_ATMEL)		+= atmel_mci.o
 obj-$(CONFIG_MCI_BCM283X)	+= mci-bcm2835.o
+obj-$(CONFIG_MCI_BCM283X_SDHOST)	+= bcm2835-sdhost.o
 obj-$(CONFIG_MCI_DOVE)		+= dove-sdhci.o
 obj-$(CONFIG_MCI_IMX)		+= imx.o
 obj-$(CONFIG_MCI_IMX_ESDHC)	+= imx-esdhc.o
diff --git a/drivers/mci/bcm2835-sdhost.c b/drivers/mci/bcm2835-sdhost.c
new file mode 100644
index 0000000000..1d3a6c0969
--- /dev/null
+++ b/drivers/mci/bcm2835-sdhost.c
@@ -0,0 +1,638 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This code is ported from U-Boot by Lucas Stach <l.stach@pengutronix.de> and
+ * has the following contributors listed in the original license header:
+ * Alexander Graf <agraf@suse.de>
+ * Phil Elwell <phil@raspberrypi.org>
+ * Gellert Weisz
+ * Stephen Warren
+ * Oleksandr Tymoshenko
+ */
+
+#include <clock.h>
+#include <common.h>
+#include <driver.h>
+#include <init.h>
+#include <linux/clk.h>
+#include <linux/iopoll.h>
+#include <linux/log2.h>
+#include <mci.h>
+
+#define SDCMD  0x00 /* Command to SD card              - 16 R/W */
+#define SDARG  0x04 /* Argument to SD card             - 32 R/W */
+#define SDTOUT 0x08 /* Start value for timeout counter - 32 R/W */
+#define SDCDIV 0x0c /* Start value for clock divider   - 11 R/W */
+#define SDRSP0 0x10 /* SD card response (31:0)         - 32 R   */
+#define SDRSP1 0x14 /* SD card response (63:32)        - 32 R   */
+#define SDRSP2 0x18 /* SD card response (95:64)        - 32 R   */
+#define SDRSP3 0x1c /* SD card response (127:96)       - 32 R   */
+#define SDHSTS 0x20 /* SD host status                  - 11 R/W */
+#define SDVDD  0x30 /* SD card power control           -  1 R/W */
+#define SDEDM  0x34 /* Emergency Debug Mode            - 13 R/W */
+#define SDHCFG 0x38 /* Host configuration              -  2 R/W */
+#define SDHBCT 0x3c /* Host byte count (debug)         - 32 R/W */
+#define SDDATA 0x40 /* Data to/from SD card            - 32 R/W */
+#define SDHBLC 0x50 /* Host block count (SDIO/SDHC)    -  9 R/W */
+
+#define SDCMD_NEW_FLAG			0x8000
+#define SDCMD_FAIL_FLAG			0x4000
+#define SDCMD_BUSYWAIT			0x800
+#define SDCMD_NO_RESPONSE		0x400
+#define SDCMD_LONG_RESPONSE		0x200
+#define SDCMD_WRITE_CMD			0x80
+#define SDCMD_READ_CMD			0x40
+#define SDCMD_CMD_MASK			0x3f
+
+#define SDCDIV_MAX_CDIV			0x7ff
+
+#define SDHSTS_BUSY_IRPT		0x400
+#define SDHSTS_BLOCK_IRPT		0x200
+#define SDHSTS_SDIO_IRPT		0x100
+#define SDHSTS_REW_TIME_OUT		0x80
+#define SDHSTS_CMD_TIME_OUT		0x40
+#define SDHSTS_CRC16_ERROR		0x20
+#define SDHSTS_CRC7_ERROR		0x10
+#define SDHSTS_FIFO_ERROR		0x08
+#define SDHSTS_DATA_FLAG		0x01
+
+#define SDHSTS_CLEAR_MASK		(SDHSTS_BUSY_IRPT | \
+					 SDHSTS_BLOCK_IRPT | \
+					 SDHSTS_SDIO_IRPT | \
+					 SDHSTS_REW_TIME_OUT | \
+					 SDHSTS_CMD_TIME_OUT | \
+					 SDHSTS_CRC16_ERROR | \
+					 SDHSTS_CRC7_ERROR | \
+					 SDHSTS_FIFO_ERROR)
+
+#define SDHSTS_TRANSFER_ERROR_MASK	(SDHSTS_CRC7_ERROR | \
+					 SDHSTS_CRC16_ERROR | \
+					 SDHSTS_REW_TIME_OUT | \
+					 SDHSTS_FIFO_ERROR)
+
+#define SDHSTS_ERROR_MASK		(SDHSTS_CMD_TIME_OUT | \
+					 SDHSTS_TRANSFER_ERROR_MASK)
+
+#define SDHCFG_BUSY_IRPT_EN	BIT(10)
+#define SDHCFG_BLOCK_IRPT_EN	BIT(8)
+#define SDHCFG_SDIO_IRPT_EN	BIT(5)
+#define SDHCFG_DATA_IRPT_EN	BIT(4)
+#define SDHCFG_SLOW_CARD	BIT(3)
+#define SDHCFG_WIDE_EXT_BUS	BIT(2)
+#define SDHCFG_WIDE_INT_BUS	BIT(1)
+#define SDHCFG_REL_CMD_LINE	BIT(0)
+
+#define SDVDD_POWER_OFF		0
+#define SDVDD_POWER_ON		1
+
+#define SDEDM_FORCE_DATA_MODE	BIT(19)
+#define SDEDM_CLOCK_PULSE	BIT(20)
+#define SDEDM_BYPASS		BIT(21)
+
+#define SDEDM_FIFO_FILL_SHIFT	4
+#define SDEDM_FIFO_FILL_MASK	0x1f
+static u32 edm_fifo_fill(u32 edm)
+{
+	return (edm >> SDEDM_FIFO_FILL_SHIFT) & SDEDM_FIFO_FILL_MASK;
+}
+
+#define SDEDM_WRITE_THRESHOLD_SHIFT	9
+#define SDEDM_READ_THRESHOLD_SHIFT	14
+#define SDEDM_THRESHOLD_MASK		0x1f
+
+#define SDEDM_FSM_MASK		0xf
+#define SDEDM_FSM_IDENTMODE	0x0
+#define SDEDM_FSM_DATAMODE	0x1
+#define SDEDM_FSM_READDATA	0x2
+#define SDEDM_FSM_WRITEDATA	0x3
+#define SDEDM_FSM_READWAIT	0x4
+#define SDEDM_FSM_READCRC	0x5
+#define SDEDM_FSM_WRITECRC	0x6
+#define SDEDM_FSM_WRITEWAIT1	0x7
+#define SDEDM_FSM_POWERDOWN	0x8
+#define SDEDM_FSM_POWERUP	0x9
+#define SDEDM_FSM_WRITESTART1	0xa
+#define SDEDM_FSM_WRITESTART2	0xb
+#define SDEDM_FSM_GENPULSES	0xc
+#define SDEDM_FSM_WRITEWAIT2	0xd
+#define SDEDM_FSM_STARTPOWDOWN	0xf
+
+#define SDDATA_FIFO_WORDS	16
+
+#define FIFO_READ_THRESHOLD	4
+#define FIFO_WRITE_THRESHOLD	4
+#define SDDATA_FIFO_PIO_BURST	8
+
+#define SDHST_TIMEOUT_MAX_USEC	100000
+
+struct bcm2835_host {
+	struct mci_host		mci;
+	void __iomem		*regs;
+	struct clk		*clk;
+};
+
+static inline struct bcm2835_host *to_bcm2835_host(struct mci_host *mci)
+{
+	return container_of(mci, struct bcm2835_host, mci);
+}
+
+static int bcm2835_sdhost_init(struct mci_host *mci, struct device_d *dev)
+{
+	struct bcm2835_host *host = to_bcm2835_host(mci);
+	u32 temp;
+
+	writel(SDVDD_POWER_OFF, host->regs + SDVDD);
+	writel(0, host->regs + SDCMD);
+	writel(0, host->regs + SDARG);
+	/* Set timeout to a big enough value so we don't hit it */
+	writel(0xf00000, host->regs + SDTOUT);
+	writel(0, host->regs + SDCDIV);
+	/* Clear status register */
+	writel(SDHSTS_CLEAR_MASK, host->regs + SDHSTS);
+	writel(0, host->regs + SDHCFG);
+	writel(0, host->regs + SDHBCT);
+	writel(0, host->regs + SDHBLC);
+
+	/* Limit fifo usage due to silicon bug */
+	temp = readl(host->regs + SDEDM);
+	temp &= ~((SDEDM_THRESHOLD_MASK << SDEDM_READ_THRESHOLD_SHIFT) |
+		  (SDEDM_THRESHOLD_MASK << SDEDM_WRITE_THRESHOLD_SHIFT));
+	temp |= (FIFO_READ_THRESHOLD << SDEDM_READ_THRESHOLD_SHIFT) |
+		(FIFO_WRITE_THRESHOLD << SDEDM_WRITE_THRESHOLD_SHIFT);
+	writel(temp, host->regs + SDEDM);
+	/* Wait for FIFO threshold to populate */
+	mdelay(20);
+	writel(SDVDD_POWER_ON, host->regs + SDVDD);
+	/* Wait for all components to go through power on cycle */
+	mdelay(20);
+	writel(0, host->regs + SDHCFG);
+	writel(0, host->regs + SDCDIV);
+
+	return 0;
+}
+
+static int bcm2835_wait_transfer_complete(struct bcm2835_host *host)
+{
+	uint64_t start = get_time_ns();
+
+	while (1) {
+		u32 edm, fsm;
+
+		edm = readl(host->regs + SDEDM);
+		fsm = edm & SDEDM_FSM_MASK;
+
+		if ((fsm == SDEDM_FSM_IDENTMODE) ||
+		    (fsm == SDEDM_FSM_DATAMODE))
+			break;
+
+		if ((fsm == SDEDM_FSM_READWAIT) ||
+		    (fsm == SDEDM_FSM_WRITESTART1) ||
+		    (fsm == SDEDM_FSM_READDATA)) {
+			writel(edm | SDEDM_FORCE_DATA_MODE,
+			       host->regs + SDEDM);
+			break;
+		}
+
+		/* Error out after 1 second */
+		if (is_timeout(start, 1 * SECOND)) {
+			dev_err(host->mci.hw_dev,
+				"wait_transfer_complete - still waiting 1s\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}
+
+static int bcm2835_transfer_block_pio(struct bcm2835_host *host,
+				      struct mci_data *data, unsigned int block,
+				      bool is_read)
+{
+	u32 *buf = is_read ? (u32 *)data->dest : (u32 *)data->src;
+	int copy_words = data->blocksize / sizeof(u32);
+	uint64_t start = get_time_ns();
+
+	if (data->blocksize % sizeof(u32))
+		return -EINVAL;
+
+	buf += (block * data->blocksize / sizeof(u32));
+
+	/* Copy all contents from/to the FIFO as far as it reaches. */
+	while (copy_words) {
+		int fifo_words;
+		u32 edm;
+
+		if (is_timeout(start, 100 * MSECOND)) {
+			dev_err(host->mci.hw_dev,
+				"transfer_block_pio timeout\n");
+			return -ETIMEDOUT;
+		}
+
+		edm = readl(host->regs + SDEDM);
+		if (is_read)
+			fifo_words = edm_fifo_fill(edm);
+		else
+			fifo_words = SDDATA_FIFO_WORDS - edm_fifo_fill(edm);
+
+		if (fifo_words > copy_words)
+			fifo_words = copy_words;
+
+		/* Copy current chunk to/from the FIFO */
+		while (fifo_words) {
+			if (is_read)
+				*(buf++) = readl(host->regs + SDDATA);
+			else
+				writel(*(buf++), host->regs + SDDATA);
+			fifo_words--;
+			copy_words--;
+		}
+	}
+
+	return 0;
+}
+
+static int bcm2835_transfer_pio(struct bcm2835_host *host,
+				struct mci_data *data)
+{
+	u32 sdhsts;
+	bool is_read = !!(data->flags & MMC_DATA_READ);
+	unsigned int block = 0;
+	int ret = 0;
+
+	while (block < data->blocks) {
+		ret = bcm2835_transfer_block_pio(host, data, block, is_read);
+		if (ret)
+			return ret;
+
+		sdhsts = readl(host->regs + SDHSTS);
+		if (sdhsts & (SDHSTS_CRC16_ERROR |
+			      SDHSTS_CRC7_ERROR |
+			      SDHSTS_FIFO_ERROR)) {
+			dev_err(host->mci.hw_dev,
+				"%s transfer error - HSTS %08x\n",
+				is_read ? "read" : "write", sdhsts);
+			ret =  -EILSEQ;
+		} else if ((sdhsts & (SDHSTS_CMD_TIME_OUT |
+				      SDHSTS_REW_TIME_OUT))) {
+			dev_err(host->mci.hw_dev,
+				"%s timeout error - HSTS %08x\n",
+				is_read ? "read" : "write", sdhsts);
+			ret = -ETIMEDOUT;
+		}
+		block++;
+	}
+
+	return ret;
+}
+
+static u32 bcm2835_read_wait_sdcmd(struct bcm2835_host *host)
+{
+	u32 value;
+	int ret;
+	int timeout_us = SDHST_TIMEOUT_MAX_USEC;
+
+	ret = readl_poll_timeout(host->regs + SDCMD, value,
+				 !(value & SDCMD_NEW_FLAG), timeout_us);
+	if (ret == -ETIMEDOUT)
+		dev_err(host->mci.hw_dev, "%s: timeout (%d us)\n",
+			__func__, timeout_us);
+
+	return value;
+}
+
+static int bcm2835_send_command(struct bcm2835_host *host, struct mci_cmd *cmd,
+				struct mci_data *data)
+{
+	u32 sdcmd, sdhsts;
+
+	if ((cmd->resp_type & MMC_RSP_136) && (cmd->resp_type & MMC_RSP_BUSY)) {
+		dev_err(host->mci.hw_dev, "unsupported response type!\n");
+		return -EINVAL;
+	}
+
+	sdcmd = bcm2835_read_wait_sdcmd(host);
+	if (sdcmd & SDCMD_NEW_FLAG) {
+		dev_err(host->mci.hw_dev, "previous command never completed.\n");
+		return -EBUSY;
+	}
+
+	/* Clear any error flags */
+	sdhsts = readl(host->regs + SDHSTS);
+	if (sdhsts & SDHSTS_ERROR_MASK)
+		writel(sdhsts, host->regs + SDHSTS);
+
+	if (data) {
+		writel(data->blocksize, host->regs + SDHBCT);
+		writel(data->blocks, host->regs + SDHBLC);
+	}
+
+	writel(cmd->cmdarg, host->regs + SDARG);
+
+	sdcmd = cmd->cmdidx & SDCMD_CMD_MASK;
+
+	if (!(cmd->resp_type & MMC_RSP_PRESENT)) {
+		sdcmd |= SDCMD_NO_RESPONSE;
+	} else {
+		if (cmd->resp_type & MMC_RSP_136)
+			sdcmd |= SDCMD_LONG_RESPONSE;
+		if (cmd->resp_type & MMC_RSP_BUSY)
+			sdcmd |= SDCMD_BUSYWAIT;
+	}
+
+	if (data) {
+		if (data->flags & MMC_DATA_WRITE)
+			sdcmd |= SDCMD_WRITE_CMD;
+		if (data->flags & MMC_DATA_READ)
+			sdcmd |= SDCMD_READ_CMD;
+	}
+
+	writel(sdcmd | SDCMD_NEW_FLAG, host->regs + SDCMD);
+
+	return 0;
+}
+
+static int bcm2835_finish_command(struct bcm2835_host *host,
+				  struct mci_cmd *cmd)
+{
+	u32 sdcmd;
+	int ret = 0;
+
+	sdcmd = bcm2835_read_wait_sdcmd(host);
+
+	/* Check for errors */
+	if (sdcmd & SDCMD_NEW_FLAG) {
+		dev_err(host->mci.hw_dev, "command never completed.\n");
+		return -EIO;
+	} else if (sdcmd & SDCMD_FAIL_FLAG) {
+		u32 sdhsts = readl(host->regs + SDHSTS);
+
+		/* Clear the errors */
+		writel(SDHSTS_ERROR_MASK, host->regs + SDHSTS);
+
+		if (!(sdhsts & SDHSTS_CRC7_ERROR) ||
+		    (cmd->cmdidx != MMC_CMD_SEND_OP_COND)) {
+			if (sdhsts & SDHSTS_CMD_TIME_OUT) {
+				ret = -ETIMEDOUT;
+			} else {
+				dev_err(host->mci.hw_dev,
+					"unexpected command %d error\n",
+					cmd->cmdidx);
+				ret = -EILSEQ;
+			}
+
+			return ret;
+		}
+	}
+
+	if (cmd->resp_type & MMC_RSP_PRESENT) {
+		if (cmd->resp_type & MMC_RSP_136) {
+			int i;
+
+			for (i = 0; i < 4; i++) {
+				cmd->response[3 - i] =
+					readl(host->regs + SDRSP0 + i * 4);
+			}
+		} else {
+			cmd->response[0] = readl(host->regs + SDRSP0);
+		}
+	}
+
+	return ret;
+}
+
+static int bcm2835_check_cmd_error(struct bcm2835_host *host, u32 intmask)
+{
+	int ret = -EINVAL;
+
+	if (!(intmask & SDHSTS_ERROR_MASK))
+		return 0;
+
+	dev_err(host->mci.hw_dev, "sdhost_busy_irq: intmask %08x\n", intmask);
+	if (intmask & SDHSTS_CRC7_ERROR) {
+		ret = -EILSEQ;
+	} else if (intmask & (SDHSTS_CRC16_ERROR |
+			      SDHSTS_FIFO_ERROR)) {
+		ret = -EILSEQ;
+	} else if (intmask & (SDHSTS_REW_TIME_OUT | SDHSTS_CMD_TIME_OUT)) {
+		ret = -ETIMEDOUT;
+	}
+
+	return ret;
+}
+
+static int bcm2835_check_data_error(struct bcm2835_host *host, u32 intmask)
+{
+	int ret = 0;
+
+	if (intmask & (SDHSTS_CRC16_ERROR | SDHSTS_FIFO_ERROR))
+		ret = -EILSEQ;
+	if (intmask & SDHSTS_REW_TIME_OUT)
+		ret = -ETIMEDOUT;
+
+	if (ret)
+		dev_err(host->mci.hw_dev, "data error %d\n", ret);
+
+	return ret;
+}
+
+static int bcm2835_transmit(struct bcm2835_host *host, struct mci_cmd *cmd,
+			    struct mci_data *data)
+{
+	u32 intmask = readl(host->regs + SDHSTS);
+	int ret;
+
+	/* Check for errors */
+	if (data) {
+		ret = bcm2835_check_data_error(host, intmask);
+		if (ret)
+			return ret;
+	}
+
+	ret = bcm2835_check_cmd_error(host, intmask);
+	if (ret)
+		return ret;
+
+	/* Handle wait for busy end */
+	if ((cmd->resp_type & MMC_RSP_BUSY) &&
+	    (intmask & SDHSTS_BUSY_IRPT)) {
+		writel(SDHSTS_BUSY_IRPT, host->regs + SDHSTS);
+		bcm2835_finish_command(host, cmd);
+	}
+
+	/* Handle PIO data transfer */
+	if (data) {
+		ret = bcm2835_transfer_pio(host, data);
+		if (ret)
+			return ret;
+		/* Transfer successful: wait for command to complete for real */
+		ret = bcm2835_wait_transfer_complete(host);
+	}
+
+	return ret;
+}
+
+static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
+{
+	int div;
+
+	/* The SDCDIV register has 11 bits, and holds (div - 2).  But
+	 * in data mode the max is 50MHz without a minimum, and only
+	 * the bottom 3 bits are used. Since the switch over is
+	 * automatic (unless we have marked the card as slow...),
+	 * chosen values have to make sense in both modes. Ident mode
+	 * must be 100-400KHz, so can range check the requested
+	 * clock. CMD15 must be used to return to data mode, so this
+	 * can be monitored.
+	 *
+	 * clock 250MHz -> 0->125MHz, 1->83.3MHz, 2->62.5MHz, 3->50.0MHz
+	 *                 4->41.7MHz, 5->35.7MHz, 6->31.3MHz, 7->27.8MHz
+	 *
+	 *		 623->400KHz/27.8MHz
+	 *		 reset value (507)->491159/50MHz
+	 *
+	 * BUT, the 3-bit clock divisor in data mode is too small if
+	 * the core clock is higher than 250MHz, so instead use the
+	 * SLOW_CARD configuration bit to force the use of the ident
+	 * clock divisor at all times.
+	 */
+
+	if (clock < 100000) {
+		/* Can't stop the clock, but make it as slow as possible
+		 * to show willing
+		 */
+		writel(SDCDIV_MAX_CDIV, host->regs + SDCDIV);
+		return;
+	}
+
+	div = host->mci.f_max / clock;
+	if (div < 2)
+		div = 2;
+	if ((host->mci.f_max / div) > clock)
+		div++;
+	div -= 2;
+
+	if (div > SDCDIV_MAX_CDIV)
+		div = SDCDIV_MAX_CDIV;
+
+	clock = host->mci.f_max / (div + 2);
+
+	writel(div, host->regs + SDCDIV);
+
+	/* Set the timeout to 500ms */
+	writel(clock / 2, host->regs + SDTOUT);
+}
+
+static int bcm2835_send_cmd(struct mci_host *mci, struct mci_cmd *cmd,
+			    struct mci_data *data)
+{
+	struct bcm2835_host *host = to_bcm2835_host(mci);
+	u32 edm, fsm;
+	int ret = 0;
+
+	if (data && !is_power_of_2(data->blocksize)) {
+		dev_err(mci->hw_dev, "unsupported block size (%d bytes)\n",
+			data->blocksize);
+		return -EINVAL;
+	}
+
+	edm = readl(host->regs + SDEDM);
+	fsm = edm & SDEDM_FSM_MASK;
+
+	if ((fsm != SDEDM_FSM_IDENTMODE) &&
+	    (fsm != SDEDM_FSM_DATAMODE) &&
+	    (cmd->cmdidx != MMC_CMD_STOP_TRANSMISSION)) {
+		dev_err(mci->hw_dev,
+			"previous command (%d) not complete (EDM %08x)\n",
+			readl(host->regs + SDCMD) & SDCMD_CMD_MASK, edm);
+
+		return -EILSEQ;
+	}
+
+	ret = bcm2835_send_command(host, cmd, data);
+	if (ret)
+		return ret;
+
+	if (!(cmd->resp_type & MMC_RSP_BUSY)) {
+		ret = bcm2835_finish_command(host, cmd);
+		if (ret)
+			return ret;
+	}
+
+	/* Wait for completion of busy signal or data transfer */
+	if ((cmd->resp_type & MMC_RSP_BUSY) || data)
+		ret = bcm2835_transmit(host, cmd, data);
+
+	return ret;
+}
+
+static void bcm2835_set_ios(struct mci_host *mci, struct mci_ios *ios)
+{
+	struct bcm2835_host *host = to_bcm2835_host(mci);
+	u32 hcfg = SDHCFG_WIDE_INT_BUS | SDHCFG_SLOW_CARD;
+
+	if (ios->clock)
+		bcm2835_set_clock(host, ios->clock);
+
+	/* set bus width */
+	if (ios->bus_width == MMC_BUS_WIDTH_4)
+		hcfg |= SDHCFG_WIDE_EXT_BUS;
+
+	writel(hcfg, host->regs + SDHCFG);
+}
+
+static int bcm2835_sdhost_detect(struct device_d *dev)
+{
+	struct bcm2835_host *host = dev->priv;
+
+	return mci_detect_card(&host->mci);
+}
+
+static int bcm2835_sdhost_probe(struct device_d *dev)
+{
+	struct bcm2835_host *host;
+	struct resource *iores;
+	struct mci_host *mci;
+
+	host = xzalloc(sizeof(*host));
+	mci = &host->mci;
+
+	host->clk = clk_get(dev, NULL);
+	if (IS_ERR(host->clk))
+		return PTR_ERR(host->clk);
+
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores)) {
+		dev_err(dev, "could not get iomem region\n");
+		return PTR_ERR(iores);
+	}
+	host->regs = IOMEM(iores->start);
+
+	mci->hw_dev = dev;
+	mci->f_max = clk_get_rate(host->clk);
+	mci->f_min = mci->f_max / SDCDIV_MAX_CDIV;
+	mci->voltages = MMC_VDD_32_33 | MMC_VDD_33_34;
+	mci->host_caps |= MMC_CAP_MMC_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED_52MHZ |
+			  MMC_CAP_SD_HIGHSPEED;
+
+	mci->init = bcm2835_sdhost_init;
+	mci->set_ios = bcm2835_set_ios;
+	mci->send_cmd = bcm2835_send_cmd;
+
+	dev->priv = host;
+	dev->detect = bcm2835_sdhost_detect,
+
+	mci_of_parse(mci);
+
+	return mci_register(mci);
+}
+
+static __maybe_unused struct of_device_id bcm2835_sdhost_compatible[] = {
+	{ .compatible = "brcm,bcm2835-sdhost" },
+	{ /* sentinel */ }
+};
+
+static struct driver_d bcm2835_sdhost_driver = {
+	.name  = "bcm2835-sdhost",
+	.probe = bcm2835_sdhost_probe,
+	.of_compatible = DRV_OF_COMPAT(bcm2835_sdhost_compatible),
+};
+device_platform_driver(bcm2835_sdhost_driver);
-- 
2.20.1


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