Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1484 insertions, 0 deletions

diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c
new file mode 100644
index 000000000..c15226be4
--- /dev/null
+++ b/drivers/mmc/host/bcm2835.c
@@ -0,0 +1,1484 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcm2835 sdhost driver.
+ *
+ * The 2835 has two SD controllers: The Arasan sdhci controller
+ * (supported by the iproc driver) and a custom sdhost controller
+ * (supported by this driver).
+ *
+ * The sdhci controller supports both sdcard and sdio.  The sdhost
+ * controller supports the sdcard only, but has better performance.
+ * Also note that the rpi3 has sdio wifi, so driving the sdcard with
+ * the sdhost controller allows to use the sdhci controller for wifi
+ * support.
+ *
+ * The configuration is done by devicetree via pin muxing.  Both
+ * SD controller are available on the same pins (2 pin groups = pin 22
+ * to 27 + pin 48 to 53).  So it's possible to use both SD controllers
+ * at the same time with different pin groups.
+ *
+ * Author:      Phil Elwell <phil@raspberrypi.org>
+ *              Copyright (C) 2015-2016 Raspberry Pi (Trading) Ltd.
+ *
+ * Based on
+ *  mmc-bcm2835.c by Gellert Weisz
+ * which is, in turn, based on
+ *  sdhci-bcm2708.c by Broadcom
+ *  sdhci-bcm2835.c by Stephen Warren and Oleksandr Tymoshenko
+ *  sdhci.c and sdhci-pci.c by Pierre Ossman
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/highmem.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/scatterlist.h>
+#include <linux/time.h>
+#include <linux/workqueue.h>
+
+#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>
+#include <linux/mmc/sd.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
+/* Reserved */
+/* Reserved */
+#define SDHSTS_DATA_FLAG		0x01
+
+#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_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 PIO_THRESHOLD	1  /* Maximum block count for PIO (0 = always DMA) */
+
+struct bcm2835_host {
+	spinlock_t		lock;
+	struct mutex		mutex;
+
+	void __iomem		*ioaddr;
+	u32			phys_addr;
+
+	struct platform_device	*pdev;
+
+	int			clock;		/* Current clock speed */
+	unsigned int		max_clk;	/* Max possible freq */
+	struct work_struct	dma_work;
+	struct delayed_work	timeout_work;	/* Timer for timeouts */
+	struct sg_mapping_iter	sg_miter;	/* SG state for PIO */
+	unsigned int		blocks;		/* remaining PIO blocks */
+	int			irq;		/* Device IRQ */
+
+	u32			ns_per_fifo_word;
+
+	/* cached registers */
+	u32			hcfg;
+	u32			cdiv;
+
+	struct mmc_request	*mrq;		/* Current request */
+	struct mmc_command	*cmd;		/* Current command */
+	struct mmc_data		*data;		/* Current data request */
+	bool			data_complete:1;/* Data finished before cmd */
+	bool			use_busy:1;	/* Wait for busy interrupt */
+	bool			use_sbc:1;	/* Send CMD23 */
+
+	/* for threaded irq handler */
+	bool			irq_block;
+	bool			irq_busy;
+	bool			irq_data;
+
+	/* DMA part */
+	struct dma_chan		*dma_chan_rxtx;
+	struct dma_chan		*dma_chan;
+	struct dma_slave_config dma_cfg_rx;
+	struct dma_slave_config dma_cfg_tx;
+	struct dma_async_tx_descriptor	*dma_desc;
+	u32			dma_dir;
+	u32			drain_words;
+	struct page		*drain_page;
+	u32			drain_offset;
+	bool			use_dma;
+};
+
+static void bcm2835_dumpcmd(struct bcm2835_host *host, struct mmc_command *cmd,
+			    const char *label)
+{
+	struct device *dev = &host->pdev->dev;
+
+	if (!cmd)
+		return;
+
+	dev_dbg(dev, "%c%s op %d arg 0x%x flags 0x%x - resp %08x %08x %08x %08x, err %d\n",
+		(cmd == host->cmd) ? '>' : ' ',
+		label, cmd->opcode, cmd->arg, cmd->flags,
+		cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3],
+		cmd->error);
+}
+
+static void bcm2835_dumpregs(struct bcm2835_host *host)
+{
+	struct mmc_request *mrq = host->mrq;
+	struct device *dev = &host->pdev->dev;
+
+	if (mrq) {
+		bcm2835_dumpcmd(host, mrq->sbc, "sbc");
+		bcm2835_dumpcmd(host, mrq->cmd, "cmd");
+		if (mrq->data) {
+			dev_dbg(dev, "data blocks %x blksz %x - err %d\n",
+				mrq->data->blocks,
+				mrq->data->blksz,
+				mrq->data->error);
+		}
+		bcm2835_dumpcmd(host, mrq->stop, "stop");
+	}
+
+	dev_dbg(dev, "=========== REGISTER DUMP ===========\n");
+	dev_dbg(dev, "SDCMD  0x%08x\n", readl(host->ioaddr + SDCMD));
+	dev_dbg(dev, "SDARG  0x%08x\n", readl(host->ioaddr + SDARG));
+	dev_dbg(dev, "SDTOUT 0x%08x\n", readl(host->ioaddr + SDTOUT));
+	dev_dbg(dev, "SDCDIV 0x%08x\n", readl(host->ioaddr + SDCDIV));
+	dev_dbg(dev, "SDRSP0 0x%08x\n", readl(host->ioaddr + SDRSP0));
+	dev_dbg(dev, "SDRSP1 0x%08x\n", readl(host->ioaddr + SDRSP1));
+	dev_dbg(dev, "SDRSP2 0x%08x\n", readl(host->ioaddr + SDRSP2));
+	dev_dbg(dev, "SDRSP3 0x%08x\n", readl(host->ioaddr + SDRSP3));
+	dev_dbg(dev, "SDHSTS 0x%08x\n", readl(host->ioaddr + SDHSTS));
+	dev_dbg(dev, "SDVDD  0x%08x\n", readl(host->ioaddr + SDVDD));
+	dev_dbg(dev, "SDEDM  0x%08x\n", readl(host->ioaddr + SDEDM));
+	dev_dbg(dev, "SDHCFG 0x%08x\n", readl(host->ioaddr + SDHCFG));
+	dev_dbg(dev, "SDHBCT 0x%08x\n", readl(host->ioaddr + SDHBCT));
+	dev_dbg(dev, "SDHBLC 0x%08x\n", readl(host->ioaddr + SDHBLC));
+	dev_dbg(dev, "===========================================\n");
+}
+
+static void bcm2835_reset_internal(struct bcm2835_host *host)
+{
+	u32 temp;
+
+	writel(SDVDD_POWER_OFF, host->ioaddr + SDVDD);
+	writel(0, host->ioaddr + SDCMD);
+	writel(0, host->ioaddr + SDARG);
+	writel(0xf00000, host->ioaddr + SDTOUT);
+	writel(0, host->ioaddr + SDCDIV);
+	writel(0x7f8, host->ioaddr + SDHSTS); /* Write 1s to clear */
+	writel(0, host->ioaddr + SDHCFG);
+	writel(0, host->ioaddr + SDHBCT);
+	writel(0, host->ioaddr + SDHBLC);
+
+	/* Limit fifo usage due to silicon bug */
+	temp = readl(host->ioaddr + 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->ioaddr + SDEDM);
+	msleep(20);
+	writel(SDVDD_POWER_ON, host->ioaddr + SDVDD);
+	msleep(20);
+	host->clock = 0;
+	writel(host->hcfg, host->ioaddr + SDHCFG);
+	writel(host->cdiv, host->ioaddr + SDCDIV);
+}
+
+static void bcm2835_reset(struct mmc_host *mmc)
+{
+	struct bcm2835_host *host = mmc_priv(mmc);
+
+	if (host->dma_chan)
+		dmaengine_terminate_sync(host->dma_chan);
+	host->dma_chan = NULL;
+	bcm2835_reset_internal(host);
+}
+
+static void bcm2835_finish_command(struct bcm2835_host *host);
+
+static void bcm2835_wait_transfer_complete(struct bcm2835_host *host)
+{
+	int timediff;
+	u32 alternate_idle;
+
+	alternate_idle = (host->mrq->data->flags & MMC_DATA_READ) ?
+		SDEDM_FSM_READWAIT : SDEDM_FSM_WRITESTART1;
+
+	timediff = 0;
+
+	while (1) {
+		u32 edm, fsm;
+
+		edm = readl(host->ioaddr + SDEDM);
+		fsm = edm & SDEDM_FSM_MASK;
+
+		if ((fsm == SDEDM_FSM_IDENTMODE) ||
+		    (fsm == SDEDM_FSM_DATAMODE))
+			break;
+		if (fsm == alternate_idle) {
+			writel(edm | SDEDM_FORCE_DATA_MODE,
+			       host->ioaddr + SDEDM);
+			break;
+		}
+
+		timediff++;
+		if (timediff == 100000) {
+			dev_err(&host->pdev->dev,
+				"wait_transfer_complete - still waiting after %d retries\n",
+				timediff);
+			bcm2835_dumpregs(host);
+			host->mrq->data->error = -ETIMEDOUT;
+			return;
+		}
+		cpu_relax();
+	}
+}
+
+static void bcm2835_dma_complete(void *param)
+{
+	struct bcm2835_host *host = param;
+
+	schedule_work(&host->dma_work);
+}
+
+static void bcm2835_transfer_block_pio(struct bcm2835_host *host, bool is_read)
+{
+	unsigned long flags;
+	size_t blksize;
+	unsigned long wait_max;
+
+	blksize = host->data->blksz;
+
+	wait_max = jiffies + msecs_to_jiffies(500);
+
+	local_irq_save(flags);
+
+	while (blksize) {
+		int copy_words;
+		u32 hsts = 0;
+		size_t len;
+		u32 *buf;
+
+		if (!sg_miter_next(&host->sg_miter)) {
+			host->data->error = -EINVAL;
+			break;
+		}
+
+		len = min(host->sg_miter.length, blksize);
+		if (len % 4) {
+			host->data->error = -EINVAL;
+			break;
+		}
+
+		blksize -= len;
+		host->sg_miter.consumed = len;
+
+		buf = (u32 *)host->sg_miter.addr;
+
+		copy_words = len / 4;
+
+		while (copy_words) {
+			int burst_words, words;
+			u32 edm;
+
+			burst_words = min(SDDATA_FIFO_PIO_BURST, copy_words);
+			edm = readl(host->ioaddr + SDEDM);
+			if (is_read)
+				words = ((edm >> 4) & 0x1f);
+			else
+				words = SDDATA_FIFO_WORDS - ((edm >> 4) & 0x1f);
+
+			if (words < burst_words) {
+				int fsm_state = (edm & SDEDM_FSM_MASK);
+				struct device *dev = &host->pdev->dev;
+
+				if ((is_read &&
+				     (fsm_state != SDEDM_FSM_READDATA &&
+				      fsm_state != SDEDM_FSM_READWAIT &&
+				      fsm_state != SDEDM_FSM_READCRC)) ||
+				    (!is_read &&
+				     (fsm_state != SDEDM_FSM_WRITEDATA &&
+				      fsm_state != SDEDM_FSM_WRITESTART1 &&
+				      fsm_state != SDEDM_FSM_WRITESTART2))) {
+					hsts = readl(host->ioaddr + SDHSTS);
+					dev_err(dev, "fsm %x, hsts %08x\n",
+						fsm_state, hsts);
+					if (hsts & SDHSTS_ERROR_MASK)
+						break;
+				}
+
+				if (time_after(jiffies, wait_max)) {
+					dev_err(dev, "PIO %s timeout - EDM %08x\n",
+						is_read ? "read" : "write",
+						edm);
+					hsts = SDHSTS_REW_TIME_OUT;
+					break;
+				}
+				ndelay((burst_words - words) *
+				       host->ns_per_fifo_word);
+				continue;
+			} else if (words > copy_words) {
+				words = copy_words;
+			}
+
+			copy_words -= words;
+
+			while (words) {
+				if (is_read)
+					*(buf++) = readl(host->ioaddr + SDDATA);
+				else
+					writel(*(buf++), host->ioaddr + SDDATA);
+				words--;
+			}
+		}
+
+		if (hsts & SDHSTS_ERROR_MASK)
+			break;
+	}
+
+	sg_miter_stop(&host->sg_miter);
+
+	local_irq_restore(flags);
+}
+
+static void bcm2835_transfer_pio(struct bcm2835_host *host)
+{
+	struct device *dev = &host->pdev->dev;
+	u32 sdhsts;
+	bool is_read;
+
+	is_read = (host->data->flags & MMC_DATA_READ) != 0;
+	bcm2835_transfer_block_pio(host, is_read);
+
+	sdhsts = readl(host->ioaddr + SDHSTS);
+	if (sdhsts & (SDHSTS_CRC16_ERROR |
+		      SDHSTS_CRC7_ERROR |
+		      SDHSTS_FIFO_ERROR)) {
+		dev_err(dev, "%s transfer error - HSTS %08x\n",
+			is_read ? "read" : "write", sdhsts);
+		host->data->error = -EILSEQ;
+	} else if ((sdhsts & (SDHSTS_CMD_TIME_OUT |
+			      SDHSTS_REW_TIME_OUT))) {
+		dev_err(dev, "%s timeout error - HSTS %08x\n",
+			is_read ? "read" : "write", sdhsts);
+		host->data->error = -ETIMEDOUT;
+	}
+}
+
+static
+void bcm2835_prepare_dma(struct bcm2835_host *host, struct mmc_data *data)
+{
+	int sg_len, dir_data, dir_slave;
+	struct dma_async_tx_descriptor *desc = NULL;
+	struct dma_chan *dma_chan;
+
+	dma_chan = host->dma_chan_rxtx;
+	if (data->flags & MMC_DATA_READ) {
+		dir_data = DMA_FROM_DEVICE;
+		dir_slave = DMA_DEV_TO_MEM;
+	} else {
+		dir_data = DMA_TO_DEVICE;
+		dir_slave = DMA_MEM_TO_DEV;
+	}
+
+	/* The block doesn't manage the FIFO DREQs properly for
+	 * multi-block transfers, so don't attempt to DMA the final
+	 * few words.  Unfortunately this requires the final sg entry
+	 * to be trimmed.  N.B. This code demands that the overspill
+	 * is contained in a single sg entry.
+	 */
+
+	host->drain_words = 0;
+	if ((data->blocks > 1) && (dir_data == DMA_FROM_DEVICE)) {
+		struct scatterlist *sg;
+		u32 len;
+		int i;
+
+		len = min((u32)(FIFO_READ_THRESHOLD - 1) * 4,
+			  (u32)data->blocks * data->blksz);
+
+		for_each_sg(data->sg, sg, data->sg_len, i) {
+			if (sg_is_last(sg)) {
+				WARN_ON(sg->length < len);
+				sg->length -= len;
+				host->drain_page = sg_page(sg);
+				host->drain_offset = sg->offset + sg->length;
+			}
+		}
+		host->drain_words = len / 4;
+	}
+
+	/* The parameters have already been validated, so this will not fail */
+	(void)dmaengine_slave_config(dma_chan,
+				     (dir_data == DMA_FROM_DEVICE) ?
+				     &host->dma_cfg_rx :
+				     &host->dma_cfg_tx);
+
+	sg_len = dma_map_sg(dma_chan->device->dev, data->sg, data->sg_len,
+			    dir_data);
+	if (!sg_len)
+		return;
+
+	desc = dmaengine_prep_slave_sg(dma_chan, data->sg, sg_len, dir_slave,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
+	if (!desc) {
+		dma_unmap_sg(dma_chan->device->dev, data->sg, sg_len, dir_data);
+		return;
+	}
+
+	desc->callback = bcm2835_dma_complete;
+	desc->callback_param = host;
+	host->dma_desc = desc;
+	host->dma_chan = dma_chan;
+	host->dma_dir = dir_data;
+}
+
+static void bcm2835_start_dma(struct bcm2835_host *host)
+{
+	dmaengine_submit(host->dma_desc);
+	dma_async_issue_pending(host->dma_chan);
+}
+
+static void bcm2835_set_transfer_irqs(struct bcm2835_host *host)
+{
+	u32 all_irqs = SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN |
+		SDHCFG_BUSY_IRPT_EN;
+
+	if (host->dma_desc) {
+		host->hcfg = (host->hcfg & ~all_irqs) |
+			SDHCFG_BUSY_IRPT_EN;
+	} else {
+		host->hcfg = (host->hcfg & ~all_irqs) |
+			SDHCFG_DATA_IRPT_EN |
+			SDHCFG_BUSY_IRPT_EN;
+	}
+
+	writel(host->hcfg, host->ioaddr + SDHCFG);
+}
+
+static
+void bcm2835_prepare_data(struct bcm2835_host *host, struct mmc_command *cmd)
+{
+	struct mmc_data *data = cmd->data;
+
+	WARN_ON(host->data);
+
+	host->data = data;
+	if (!data)
+		return;
+
+	host->data_complete = false;
+	host->data->bytes_xfered = 0;
+
+	if (!host->dma_desc) {
+		/* Use PIO */
+		int flags = SG_MITER_ATOMIC;
+
+		if (data->flags & MMC_DATA_READ)
+			flags |= SG_MITER_TO_SG;
+		else
+			flags |= SG_MITER_FROM_SG;
+		sg_miter_start(&host->sg_miter, data->sg, data->sg_len, flags);
+		host->blocks = data->blocks;
+	}
+
+	bcm2835_set_transfer_irqs(host);
+
+	writel(data->blksz, host->ioaddr + SDHBCT);
+	writel(data->blocks, host->ioaddr + SDHBLC);
+}
+
+static u32 bcm2835_read_wait_sdcmd(struct bcm2835_host *host, u32 max_ms)
+{
+	struct device *dev = &host->pdev->dev;
+	u32 value;
+	int ret;
+
+	ret = readl_poll_timeout(host->ioaddr + SDCMD, value,
+				 !(value & SDCMD_NEW_FLAG), 1, 10);
+	if (ret == -ETIMEDOUT)
+		/* if it takes a while make poll interval bigger */
+		ret = readl_poll_timeout(host->ioaddr + SDCMD, value,
+					 !(value & SDCMD_NEW_FLAG),
+					 10, max_ms * 1000);
+	if (ret == -ETIMEDOUT)
+		dev_err(dev, "%s: timeout (%d ms)\n", __func__, max_ms);
+
+	return value;
+}
+
+static void bcm2835_finish_request(struct bcm2835_host *host)
+{
+	struct dma_chan *terminate_chan = NULL;
+	struct mmc_request *mrq;
+
+	cancel_delayed_work(&host->timeout_work);
+
+	mrq = host->mrq;
+
+	host->mrq = NULL;
+	host->cmd = NULL;
+	host->data = NULL;
+
+	host->dma_desc = NULL;
+	terminate_chan = host->dma_chan;
+	host->dma_chan = NULL;
+
+	if (terminate_chan) {
+		int err = dmaengine_terminate_all(terminate_chan);
+
+		if (err)
+			dev_err(&host->pdev->dev,
+				"failed to terminate DMA (%d)\n", err);
+	}
+
+	mmc_request_done(mmc_from_priv(host), mrq);
+}
+
+static
+bool bcm2835_send_command(struct bcm2835_host *host, struct mmc_command *cmd)
+{
+	struct device *dev = &host->pdev->dev;
+	u32 sdcmd, sdhsts;
+	unsigned long timeout;
+
+	WARN_ON(host->cmd);
+
+	sdcmd = bcm2835_read_wait_sdcmd(host, 100);
+	if (sdcmd & SDCMD_NEW_FLAG) {
+		dev_err(dev, "previous command never completed.\n");
+		bcm2835_dumpregs(host);
+		cmd->error = -EILSEQ;
+		bcm2835_finish_request(host);
+		return false;
+	}
+
+	if (!cmd->data && cmd->busy_timeout > 9000)
+		timeout = DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
+	else
+		timeout = 10 * HZ;
+	schedule_delayed_work(&host->timeout_work, timeout);
+
+	host->cmd = cmd;
+
+	/* Clear any error flags */
+	sdhsts = readl(host->ioaddr + SDHSTS);
+	if (sdhsts & SDHSTS_ERROR_MASK)
+		writel(sdhsts, host->ioaddr + SDHSTS);
+
+	if ((cmd->flags & MMC_RSP_136) && (cmd->flags & MMC_RSP_BUSY)) {
+		dev_err(dev, "unsupported response type!\n");
+		cmd->error = -EINVAL;
+		bcm2835_finish_request(host);
+		return false;
+	}
+
+	bcm2835_prepare_data(host, cmd);
+
+	writel(cmd->arg, host->ioaddr + SDARG);
+
+	sdcmd = cmd->opcode & SDCMD_CMD_MASK;
+
+	host->use_busy = false;
+	if (!(cmd->flags & MMC_RSP_PRESENT)) {
+		sdcmd |= SDCMD_NO_RESPONSE;
+	} else {
+		if (cmd->flags & MMC_RSP_136)
+			sdcmd |= SDCMD_LONG_RESPONSE;
+		if (cmd->flags & MMC_RSP_BUSY) {
+			sdcmd |= SDCMD_BUSYWAIT;
+			host->use_busy = true;
+		}
+	}
+
+	if (cmd->data) {
+		if (cmd->data->flags & MMC_DATA_WRITE)
+			sdcmd |= SDCMD_WRITE_CMD;
+		if (cmd->data->flags & MMC_DATA_READ)
+			sdcmd |= SDCMD_READ_CMD;
+	}
+
+	writel(sdcmd | SDCMD_NEW_FLAG, host->ioaddr + SDCMD);
+
+	return true;
+}
+
+static void bcm2835_transfer_complete(struct bcm2835_host *host)
+{
+	struct mmc_data *data;
+
+	WARN_ON(!host->data_complete);
+
+	data = host->data;
+	host->data = NULL;
+
+	/* Need to send CMD12 if -
+	 * a) open-ended multiblock transfer (no CMD23)
+	 * b) error in multiblock transfer
+	 */
+	if (host->mrq->stop && (data->error || !host->use_sbc)) {
+		if (bcm2835_send_command(host, host->mrq->stop)) {
+			/* No busy, so poll for completion */
+			if (!host->use_busy)
+				bcm2835_finish_command(host);
+		}
+	} else {
+		bcm2835_wait_transfer_complete(host);
+		bcm2835_finish_request(host);
+	}
+}
+
+static void bcm2835_finish_data(struct bcm2835_host *host)
+{
+	struct device *dev = &host->pdev->dev;
+	struct mmc_data *data;
+
+	data = host->data;
+
+	host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
+	writel(host->hcfg, host->ioaddr + SDHCFG);
+
+	data->bytes_xfered = data->error ? 0 : (data->blksz * data->blocks);
+
+	host->data_complete = true;
+
+	if (host->cmd) {
+		/* Data managed to finish before the
+		 * command completed. Make sure we do
+		 * things in the proper order.
+		 */
+		dev_dbg(dev, "Finished early - HSTS %08x\n",
+			readl(host->ioaddr + SDHSTS));
+	} else {
+		bcm2835_transfer_complete(host);
+	}
+}
+
+static void bcm2835_finish_command(struct bcm2835_host *host)
+{
+	struct device *dev = &host->pdev->dev;
+	struct mmc_command *cmd = host->cmd;
+	u32 sdcmd;
+
+	sdcmd = bcm2835_read_wait_sdcmd(host, 100);
+
+	/* Check for errors */
+	if (sdcmd & SDCMD_NEW_FLAG) {
+		dev_err(dev, "command never completed.\n");
+		bcm2835_dumpregs(host);
+		host->cmd->error = -EIO;
+		bcm2835_finish_request(host);
+		return;
+	} else if (sdcmd & SDCMD_FAIL_FLAG) {
+		u32 sdhsts = readl(host->ioaddr + SDHSTS);
+
+		/* Clear the errors */
+		writel(SDHSTS_ERROR_MASK, host->ioaddr + SDHSTS);
+
+		if (!(sdhsts & SDHSTS_CRC7_ERROR) ||
+		    (host->cmd->opcode != MMC_SEND_OP_COND)) {
+			u32 edm, fsm;
+
+			if (sdhsts & SDHSTS_CMD_TIME_OUT) {
+				host->cmd->error = -ETIMEDOUT;
+			} else {
+				dev_err(dev, "unexpected command %d error\n",
+					host->cmd->opcode);
+				bcm2835_dumpregs(host);
+				host->cmd->error = -EILSEQ;
+			}
+			edm = readl(host->ioaddr + SDEDM);
+			fsm = edm & SDEDM_FSM_MASK;
+			if (fsm == SDEDM_FSM_READWAIT ||
+			    fsm == SDEDM_FSM_WRITESTART1)
+				/* Kick the FSM out of its wait */
+				writel(edm | SDEDM_FORCE_DATA_MODE,
+				       host->ioaddr + SDEDM);
+			bcm2835_finish_request(host);
+			return;
+		}
+	}
+
+	if (cmd->flags & MMC_RSP_PRESENT) {
+		if (cmd->flags & MMC_RSP_136) {
+			int i;
+
+			for (i = 0; i < 4; i++) {
+				cmd->resp[3 - i] =
+					readl(host->ioaddr + SDRSP0 + i * 4);
+			}
+		} else {
+			cmd->resp[0] = readl(host->ioaddr + SDRSP0);
+		}
+	}
+
+	if (cmd == host->mrq->sbc) {
+		/* Finished CMD23, now send actual command. */
+		host->cmd = NULL;
+		if (bcm2835_send_command(host, host->mrq->cmd)) {
+			if (host->data && host->dma_desc)
+				/* DMA transfer starts now, PIO starts
+				 * after irq
+				 */
+				bcm2835_start_dma(host);
+
+			if (!host->use_busy)
+				bcm2835_finish_command(host);
+		}
+	} else if (cmd == host->mrq->stop) {
+		/* Finished CMD12 */
+		bcm2835_finish_request(host);
+	} else {
+		/* Processed actual command. */
+		host->cmd = NULL;
+		if (!host->data)
+			bcm2835_finish_request(host);
+		else if (host->data_complete)
+			bcm2835_transfer_complete(host);
+	}
+}
+
+static void bcm2835_timeout(struct work_struct *work)
+{
+	struct delayed_work *d = to_delayed_work(work);
+	struct bcm2835_host *host =
+		container_of(d, struct bcm2835_host, timeout_work);
+	struct device *dev = &host->pdev->dev;
+
+	mutex_lock(&host->mutex);
+
+	if (host->mrq) {
+		dev_err(dev, "timeout waiting for hardware interrupt.\n");
+		bcm2835_dumpregs(host);
+
+		bcm2835_reset(mmc_from_priv(host));
+
+		if (host->data) {
+			host->data->error = -ETIMEDOUT;
+			bcm2835_finish_data(host);
+		} else {
+			if (host->cmd)
+				host->cmd->error = -ETIMEDOUT;
+			else
+				host->mrq->cmd->error = -ETIMEDOUT;
+
+			bcm2835_finish_request(host);
+		}
+	}
+
+	mutex_unlock(&host->mutex);
+}
+
+static bool bcm2835_check_cmd_error(struct bcm2835_host *host, u32 intmask)
+{
+	struct device *dev = &host->pdev->dev;
+
+	if (!(intmask & SDHSTS_ERROR_MASK))
+		return false;
+
+	if (!host->cmd)
+		return true;
+
+	dev_err(dev, "sdhost_busy_irq: intmask %08x\n", intmask);
+	if (intmask & SDHSTS_CRC7_ERROR) {
+		host->cmd->error = -EILSEQ;
+	} else if (intmask & (SDHSTS_CRC16_ERROR |
+			      SDHSTS_FIFO_ERROR)) {
+		if (host->mrq->data)
+			host->mrq->data->error = -EILSEQ;
+		else
+			host->cmd->error = -EILSEQ;
+	} else if (intmask & SDHSTS_REW_TIME_OUT) {
+		if (host->mrq->data)
+			host->mrq->data->error = -ETIMEDOUT;
+		else
+			host->cmd->error = -ETIMEDOUT;
+	} else if (intmask & SDHSTS_CMD_TIME_OUT) {
+		host->cmd->error = -ETIMEDOUT;
+	}
+	bcm2835_dumpregs(host);
+	return true;
+}
+
+static void bcm2835_check_data_error(struct bcm2835_host *host, u32 intmask)
+{
+	if (!host->data)
+		return;
+	if (intmask & (SDHSTS_CRC16_ERROR | SDHSTS_FIFO_ERROR))
+		host->data->error = -EILSEQ;
+	if (intmask & SDHSTS_REW_TIME_OUT)
+		host->data->error = -ETIMEDOUT;
+}
+
+static void bcm2835_busy_irq(struct bcm2835_host *host)
+{
+	if (WARN_ON(!host->cmd)) {
+		bcm2835_dumpregs(host);
+		return;
+	}
+
+	if (WARN_ON(!host->use_busy)) {
+		bcm2835_dumpregs(host);
+		return;
+	}
+	host->use_busy = false;
+
+	bcm2835_finish_command(host);
+}
+
+static void bcm2835_data_irq(struct bcm2835_host *host, u32 intmask)
+{
+	/* There are no dedicated data/space available interrupt
+	 * status bits, so it is necessary to use the single shared
+	 * data/space available FIFO status bits. It is therefore not
+	 * an error to get here when there is no data transfer in
+	 * progress.
+	 */
+	if (!host->data)
+		return;
+
+	bcm2835_check_data_error(host, intmask);
+	if (host->data->error)
+		goto finished;
+
+	if (host->data->flags & MMC_DATA_WRITE) {
+		/* Use the block interrupt for writes after the first block */
+		host->hcfg &= ~(SDHCFG_DATA_IRPT_EN);
+		host->hcfg |= SDHCFG_BLOCK_IRPT_EN;
+		writel(host->hcfg, host->ioaddr + SDHCFG);
+		bcm2835_transfer_pio(host);
+	} else {
+		bcm2835_transfer_pio(host);
+		host->blocks--;
+		if ((host->blocks == 0) || host->data->error)
+			goto finished;
+	}
+	return;
+
+finished:
+	host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
+	writel(host->hcfg, host->ioaddr + SDHCFG);
+}
+
+static void bcm2835_data_threaded_irq(struct bcm2835_host *host)
+{
+	if (!host->data)
+		return;
+	if ((host->blocks == 0) || host->data->error)
+		bcm2835_finish_data(host);
+}
+
+static void bcm2835_block_irq(struct bcm2835_host *host)
+{
+	if (WARN_ON(!host->data)) {
+		bcm2835_dumpregs(host);
+		return;
+	}
+
+	if (!host->dma_desc) {
+		WARN_ON(!host->blocks);
+		if (host->data->error || (--host->blocks == 0))
+			bcm2835_finish_data(host);
+		else
+			bcm2835_transfer_pio(host);
+	} else if (host->data->flags & MMC_DATA_WRITE) {
+		bcm2835_finish_data(host);
+	}
+}
+
+static irqreturn_t bcm2835_irq(int irq, void *dev_id)
+{
+	irqreturn_t result = IRQ_NONE;
+	struct bcm2835_host *host = dev_id;
+	u32 intmask;
+
+	spin_lock(&host->lock);
+
+	intmask = readl(host->ioaddr + SDHSTS);
+
+	writel(SDHSTS_BUSY_IRPT |
+	       SDHSTS_BLOCK_IRPT |
+	       SDHSTS_SDIO_IRPT |
+	       SDHSTS_DATA_FLAG,
+	       host->ioaddr + SDHSTS);
+
+	if (intmask & SDHSTS_BLOCK_IRPT) {
+		bcm2835_check_data_error(host, intmask);
+		host->irq_block = true;
+		result = IRQ_WAKE_THREAD;
+	}
+
+	if (intmask & SDHSTS_BUSY_IRPT) {
+		if (!bcm2835_check_cmd_error(host, intmask)) {
+			host->irq_busy = true;
+			result = IRQ_WAKE_THREAD;
+		} else {
+			result = IRQ_HANDLED;
+		}
+	}
+
+	/* There is no true data interrupt status bit, so it is
+	 * necessary to qualify the data flag with the interrupt
+	 * enable bit.
+	 */
+	if ((intmask & SDHSTS_DATA_FLAG) &&
+	    (host->hcfg & SDHCFG_DATA_IRPT_EN)) {
+		bcm2835_data_irq(host, intmask);
+		host->irq_data = true;
+		result = IRQ_WAKE_THREAD;
+	}
+
+	spin_unlock(&host->lock);
+
+	return result;
+}
+
+static irqreturn_t bcm2835_threaded_irq(int irq, void *dev_id)
+{
+	struct bcm2835_host *host = dev_id;
+	unsigned long flags;
+	bool block, busy, data;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	block = host->irq_block;
+	busy  = host->irq_busy;
+	data  = host->irq_data;
+	host->irq_block = false;
+	host->irq_busy  = false;
+	host->irq_data  = false;
+
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	mutex_lock(&host->mutex);
+
+	if (block)
+		bcm2835_block_irq(host);
+	if (busy)
+		bcm2835_busy_irq(host);
+	if (data)
+		bcm2835_data_threaded_irq(host);
+
+	mutex_unlock(&host->mutex);
+
+	return IRQ_HANDLED;
+}
+
+static void bcm2835_dma_complete_work(struct work_struct *work)
+{
+	struct bcm2835_host *host =
+		container_of(work, struct bcm2835_host, dma_work);
+	struct mmc_data *data;
+
+	mutex_lock(&host->mutex);
+
+	data = host->data;
+
+	if (host->dma_chan) {
+		dma_unmap_sg(host->dma_chan->device->dev,
+			     data->sg, data->sg_len,
+			     host->dma_dir);
+
+		host->dma_chan = NULL;
+	}
+
+	if (host->drain_words) {
+		unsigned long flags;
+		void *page;
+		u32 *buf;
+
+		if (host->drain_offset & PAGE_MASK) {
+			host->drain_page += host->drain_offset >> PAGE_SHIFT;
+			host->drain_offset &= ~PAGE_MASK;
+		}
+		local_irq_save(flags);
+		page = kmap_atomic(host->drain_page);
+		buf = page + host->drain_offset;
+
+		while (host->drain_words) {
+			u32 edm = readl(host->ioaddr + SDEDM);
+
+			if ((edm >> 4) & 0x1f)
+				*(buf++) = readl(host->ioaddr + SDDATA);
+			host->drain_words--;
+		}
+
+		kunmap_atomic(page);
+		local_irq_restore(flags);
+	}
+
+	bcm2835_finish_data(host);
+
+	mutex_unlock(&host->mutex);
+}
+
+static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
+{
+	struct mmc_host *mmc = mmc_from_priv(host);
+	int div;
+
+	/* The SDCDIV register has 11 bits, and holds (div - 2).  But
+	 * in data mode the max is 50MHz wihout 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
+		 */
+		host->cdiv = SDCDIV_MAX_CDIV;
+		writel(host->cdiv, host->ioaddr + SDCDIV);
+		return;
+	}
+
+	div = host->max_clk / clock;
+	if (div < 2)
+		div = 2;
+	if ((host->max_clk / div) > clock)
+		div++;
+	div -= 2;
+
+	if (div > SDCDIV_MAX_CDIV)
+		div = SDCDIV_MAX_CDIV;
+
+	clock = host->max_clk / (div + 2);
+	mmc->actual_clock = clock;
+
+	/* Calibrate some delays */
+
+	host->ns_per_fifo_word = (1000000000 / clock) *
+		((mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
+
+	host->cdiv = div;
+	writel(host->cdiv, host->ioaddr + SDCDIV);
+
+	/* Set the timeout to 500ms */
+	writel(mmc->actual_clock / 2, host->ioaddr + SDTOUT);
+}
+
+static void bcm2835_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct bcm2835_host *host = mmc_priv(mmc);
+	struct device *dev = &host->pdev->dev;
+	u32 edm, fsm;
+
+	/* Reset the error statuses in case this is a retry */
+	if (mrq->sbc)
+		mrq->sbc->error = 0;
+	if (mrq->cmd)
+		mrq->cmd->error = 0;
+	if (mrq->data)
+		mrq->data->error = 0;
+	if (mrq->stop)
+		mrq->stop->error = 0;
+
+	if (mrq->data && !is_power_of_2(mrq->data->blksz)) {
+		dev_err(dev, "unsupported block size (%d bytes)\n",
+			mrq->data->blksz);
+
+		if (mrq->cmd)
+			mrq->cmd->error = -EINVAL;
+
+		mmc_request_done(mmc, mrq);
+		return;
+	}
+
+	mutex_lock(&host->mutex);
+
+	WARN_ON(host->mrq);
+	host->mrq = mrq;
+
+	edm = readl(host->ioaddr + SDEDM);
+	fsm = edm & SDEDM_FSM_MASK;
+
+	if ((fsm != SDEDM_FSM_IDENTMODE) &&
+	    (fsm != SDEDM_FSM_DATAMODE)) {
+		dev_err(dev, "previous command (%d) not complete (EDM %08x)\n",
+			readl(host->ioaddr + SDCMD) & SDCMD_CMD_MASK,
+			edm);
+		bcm2835_dumpregs(host);
+
+		if (mrq->cmd)
+			mrq->cmd->error = -EILSEQ;
+
+		bcm2835_finish_request(host);
+		mutex_unlock(&host->mutex);
+		return;
+	}
+
+	if (host->use_dma && mrq->data && (mrq->data->blocks > PIO_THRESHOLD))
+		bcm2835_prepare_dma(host, mrq->data);
+
+	host->use_sbc = !!mrq->sbc && host->mrq->data &&
+			(host->mrq->data->flags & MMC_DATA_READ);
+	if (host->use_sbc) {
+		if (bcm2835_send_command(host, mrq->sbc)) {
+			if (!host->use_busy)
+				bcm2835_finish_command(host);
+		}
+	} else if (mrq->cmd && bcm2835_send_command(host, mrq->cmd)) {
+		if (host->data && host->dma_desc) {
+			/* DMA transfer starts now, PIO starts after irq */
+			bcm2835_start_dma(host);
+		}
+
+		if (!host->use_busy)
+			bcm2835_finish_command(host);
+	}
+
+	mutex_unlock(&host->mutex);
+}
+
+static void bcm2835_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	struct bcm2835_host *host = mmc_priv(mmc);
+
+	mutex_lock(&host->mutex);
+
+	if (!ios->clock || ios->clock != host->clock) {
+		bcm2835_set_clock(host, ios->clock);
+		host->clock = ios->clock;
+	}
+
+	/* set bus width */
+	host->hcfg &= ~SDHCFG_WIDE_EXT_BUS;
+	if (ios->bus_width == MMC_BUS_WIDTH_4)
+		host->hcfg |= SDHCFG_WIDE_EXT_BUS;
+
+	host->hcfg |= SDHCFG_WIDE_INT_BUS;
+
+	/* Disable clever clock switching, to cope with fast core clocks */
+	host->hcfg |= SDHCFG_SLOW_CARD;
+
+	writel(host->hcfg, host->ioaddr + SDHCFG);
+
+	mutex_unlock(&host->mutex);
+}
+
+static const struct mmc_host_ops bcm2835_ops = {
+	.request = bcm2835_request,
+	.set_ios = bcm2835_set_ios,
+	.card_hw_reset = bcm2835_reset,
+};
+
+static int bcm2835_add_host(struct bcm2835_host *host)
+{
+	struct mmc_host *mmc = mmc_from_priv(host);
+	struct device *dev = &host->pdev->dev;
+	char pio_limit_string[20];
+	int ret;
+
+	if (!mmc->f_max || mmc->f_max > host->max_clk)
+		mmc->f_max = host->max_clk;
+	mmc->f_min = host->max_clk / SDCDIV_MAX_CDIV;
+
+	mmc->max_busy_timeout = ~0 / (mmc->f_max / 1000);
+
+	dev_dbg(dev, "f_max %d, f_min %d, max_busy_timeout %d\n",
+		mmc->f_max, mmc->f_min, mmc->max_busy_timeout);
+
+	/* host controller capabilities */
+	mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED |
+		     MMC_CAP_NEEDS_POLL | MMC_CAP_HW_RESET | MMC_CAP_CMD23;
+
+	spin_lock_init(&host->lock);
+	mutex_init(&host->mutex);
+
+	if (!host->dma_chan_rxtx) {
+		dev_warn(dev, "unable to initialise DMA channel. Falling back to PIO\n");
+		host->use_dma = false;
+	} else {
+		host->use_dma = true;
+
+		host->dma_cfg_tx.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		host->dma_cfg_tx.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		host->dma_cfg_tx.direction = DMA_MEM_TO_DEV;
+		host->dma_cfg_tx.src_addr = 0;
+		host->dma_cfg_tx.dst_addr = host->phys_addr + SDDATA;
+
+		host->dma_cfg_rx.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		host->dma_cfg_rx.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		host->dma_cfg_rx.direction = DMA_DEV_TO_MEM;
+		host->dma_cfg_rx.src_addr = host->phys_addr + SDDATA;
+		host->dma_cfg_rx.dst_addr = 0;
+
+		if (dmaengine_slave_config(host->dma_chan_rxtx,
+					   &host->dma_cfg_tx) != 0 ||
+		    dmaengine_slave_config(host->dma_chan_rxtx,
+					   &host->dma_cfg_rx) != 0)
+			host->use_dma = false;
+	}
+
+	mmc->max_segs = 128;
+	mmc->max_req_size = min_t(size_t, 524288, dma_max_mapping_size(dev));
+	mmc->max_seg_size = mmc->max_req_size;
+	mmc->max_blk_size = 1024;
+	mmc->max_blk_count =  65535;
+
+	/* report supported voltage ranges */
+	mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
+
+	INIT_WORK(&host->dma_work, bcm2835_dma_complete_work);
+	INIT_DELAYED_WORK(&host->timeout_work, bcm2835_timeout);
+
+	/* Set interrupt enables */
+	host->hcfg = SDHCFG_BUSY_IRPT_EN;
+
+	bcm2835_reset_internal(host);
+
+	ret = request_threaded_irq(host->irq, bcm2835_irq,
+				   bcm2835_threaded_irq,
+				   0, mmc_hostname(mmc), host);
+	if (ret) {
+		dev_err(dev, "failed to request IRQ %d: %d\n", host->irq, ret);
+		return ret;
+	}
+
+	ret = mmc_add_host(mmc);
+	if (ret) {
+		free_irq(host->irq, host);
+		return ret;
+	}
+
+	pio_limit_string[0] = '\0';
+	if (host->use_dma && (PIO_THRESHOLD > 0))
+		sprintf(pio_limit_string, " (>%d)", PIO_THRESHOLD);
+	dev_info(dev, "loaded - DMA %s%s\n",
+		 host->use_dma ? "enabled" : "disabled", pio_limit_string);
+
+	return 0;
+}
+
+static int bcm2835_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct clk *clk;
+	struct bcm2835_host *host;
+	struct mmc_host *mmc;
+	const __be32 *regaddr_p;
+	int ret;
+
+	dev_dbg(dev, "%s\n", __func__);
+	mmc = mmc_alloc_host(sizeof(*host), dev);
+	if (!mmc)
+		return -ENOMEM;
+
+	mmc->ops = &bcm2835_ops;
+	host = mmc_priv(mmc);
+	host->pdev = pdev;
+	spin_lock_init(&host->lock);
+
+	host->ioaddr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(host->ioaddr)) {
+		ret = PTR_ERR(host->ioaddr);
+		goto err;
+	}
+
+	/* Parse OF address directly to get the physical address for
+	 * DMA to our registers.
+	 */
+	regaddr_p = of_get_address(pdev->dev.of_node, 0, NULL, NULL);
+	if (!regaddr_p) {
+		dev_err(dev, "Can't get phys address\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	host->phys_addr = be32_to_cpup(regaddr_p);
+
+	host->dma_chan = NULL;
+	host->dma_desc = NULL;
+
+	host->dma_chan_rxtx = dma_request_chan(dev, "rx-tx");
+	if (IS_ERR(host->dma_chan_rxtx)) {
+		ret = PTR_ERR(host->dma_chan_rxtx);
+		host->dma_chan_rxtx = NULL;
+
+		if (ret == -EPROBE_DEFER)
+			goto err;
+
+		/* Ignore errors to fall back to PIO mode */
+	}
+
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		ret = dev_err_probe(dev, PTR_ERR(clk), "could not get clk\n");
+		goto err;
+	}
+
+	host->max_clk = clk_get_rate(clk);
+
+	host->irq = platform_get_irq(pdev, 0);
+	if (host->irq < 0) {
+		ret = host->irq;
+		goto err;
+	}
+
+	ret = mmc_of_parse(mmc);
+	if (ret)
+		goto err;
+
+	ret = bcm2835_add_host(host);
+	if (ret)
+		goto err;
+
+	platform_set_drvdata(pdev, host);
+
+	dev_dbg(dev, "%s -> OK\n", __func__);
+
+	return 0;
+
+err:
+	dev_dbg(dev, "%s -> err %d\n", __func__, ret);
+	if (host->dma_chan_rxtx)
+		dma_release_channel(host->dma_chan_rxtx);
+	mmc_free_host(mmc);
+
+	return ret;
+}
+
+static int bcm2835_remove(struct platform_device *pdev)
+{
+	struct bcm2835_host *host = platform_get_drvdata(pdev);
+	struct mmc_host *mmc = mmc_from_priv(host);
+
+	mmc_remove_host(mmc);
+
+	writel(SDVDD_POWER_OFF, host->ioaddr + SDVDD);
+
+	free_irq(host->irq, host);
+
+	cancel_work_sync(&host->dma_work);
+	cancel_delayed_work_sync(&host->timeout_work);
+
+	if (host->dma_chan_rxtx)
+		dma_release_channel(host->dma_chan_rxtx);
+
+	mmc_free_host(mmc);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835_match[] = {
+	{ .compatible = "brcm,bcm2835-sdhost" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bcm2835_match);
+
+static struct platform_driver bcm2835_driver = {
+	.probe      = bcm2835_probe,
+	.remove     = bcm2835_remove,
+	.driver     = {
+		.name		= "sdhost-bcm2835",
+		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table	= bcm2835_match,
+	},
+};
+module_platform_driver(bcm2835_driver);
+
+MODULE_ALIAS("platform:sdhost-bcm2835");
+MODULE_DESCRIPTION("BCM2835 SDHost driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Phil Elwell");