path: root/target/linux/brcm2708/patches-4.1/0009-Adding-bcm2835-sdhost-driver-and-an-overlay-to-enabl.patch

From 8086ce054d96d5a9a2237e5bb1d270dbce759189 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 25 Mar 2015 17:49:47 +0000
Subject: [PATCH 009/203] Adding bcm2835-sdhost driver, and an overlay to
 enable it

BCM2835 has two SD card interfaces. This driver uses the other one.

bcm2835-sdhost: Error handling fix, and code clarification

bcm2835-sdhost: Adding overclocking option

Allow a different clock speed to be substitued for a requested 50MHz.
This option is exposed using the "overclock_50" DT parameter.
Note that the sdhost interface is restricted to integer divisions of
core_freq, and the highest sensible option for a core_freq of 250MHz
is 84 (250/3 = 83.3MHz), the next being 125 (250/2) which is much too
high.

Use at your own risk.

bcm2835-sdhost: Round up the overclock, so 62 works for 62.5Mhz

Also only warn once for each overclock setting.
---
 drivers/mmc/host/Kconfig          |   10 +
 drivers/mmc/host/Makefile         |    1 +
 drivers/mmc/host/bcm2835-sdhost.c | 1702 +++++++++++++++++++++++++++++++++++++
 3 files changed, 1713 insertions(+)
 create mode 100644 drivers/mmc/host/bcm2835-sdhost.c

--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -33,6 +33,16 @@ config MMC_BCM2835_PIO_DMA_BARRIER
 
 	  If unsure, say 2 here.
 
+config MMC_BCM2835_SDHOST
+	tristate "Support for the SDHost controller on BCM2708/9"
+	depends on MACH_BCM2708 || MACH_BCM2709 || ARCH_BCM2835
+	help
+	  This selects the SDHost controller on BCM2835/6.
+
+	  If you have a controller with this interface, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_ARMMMCI
 	tristate "ARM AMBA Multimedia Card Interface support"
 	depends on ARM_AMBA
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MMC_SDHCI_S3C)	+= sdhci-s3c
 obj-$(CONFIG_MMC_SDHCI_SIRF)   	+= sdhci-sirf.o
 obj-$(CONFIG_MMC_SDHCI_F_SDH30)	+= sdhci_f_sdh30.o
 obj-$(CONFIG_MMC_SDHCI_SPEAR)	+= sdhci-spear.o
+obj-$(CONFIG_MMC_BCM2835_SDHOST)	+= bcm2835-sdhost.o
 obj-$(CONFIG_MMC_BCM2835)	+= bcm2835-mmc.o
 obj-$(CONFIG_MMC_WBSD)		+= wbsd.o
 obj-$(CONFIG_MMC_AU1X)		+= au1xmmc.o
--- /dev/null
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -0,0 +1,1702 @@
+/*
+ * BCM2835 SD host driver.
+ *
+ * Author:      Phil Elwell <phil@raspberrypi.org>
+ *              Copyright 2015
+ *
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ */
+
+#define SAFE_READ_THRESHOLD     4
+#define SAFE_WRITE_THRESHOLD    4
+#define ALLOW_DMA               1
+#define ALLOW_CMD23             0
+#define ALLOW_FAST              1
+#define USE_BLOCK_IRQ           1
+
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/mmc/mmc.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/sd.h>
+#include <linux/scatterlist.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/blkdev.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/of_dma.h>
+#include <linux/time.h>
+
+#define DRIVER_NAME "sdhost-bcm2835"
+
+#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   */
+#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_CRC16_ERROR|SDHSTS_REW_TIME_OUT|SDHSTS_FIFO_ERROR)
+#define SDHSTS_ERROR_MASK               (SDHSTS_CMD_TIME_OUT|SDHSTS_TRANSFER_ERROR_MASK)
+/* SDHSTS_CRC7_ERROR - ignore this as MMC cards generate this spuriously */
+
+#define SDHCFG_BUSY_IRPT_EN     (1<<10)
+#define SDHCFG_BLOCK_IRPT_EN    (1<<8)
+#define SDHCFG_SDIO_IRPT_EN     (1<<5)
+#define SDHCFG_DATA_IRPT_EN     (1<<4)
+#define SDHCFG_SLOW_CARD        (1<<3)
+#define SDHCFG_WIDE_EXT_BUS     (1<<2)
+#define SDHCFG_WIDE_INT_BUS     (1<<1)
+#define SDHCFG_REL_CMD_LINE     (1<<0)
+
+#define SDEDM_FORCE_DATA_MODE   (1<<19)
+#define SDEDM_CLOCK_PULSE       (1<<20)
+#define SDEDM_BYPASS            (1<<21)
+
+#define SDEDM_WRITE_THRESHOLD_SHIFT 9
+#define SDEDM_READ_THRESHOLD_SHIFT 14
+#define SDEDM_THRESHOLD_MASK     0x1f
+
+/* the inclusive limit in bytes under which PIO will be used instead of DMA */
+#ifdef CONFIG_MMC_BCM2835_SDHOST_PIO_DMA_BARRIER
+#define PIO_DMA_BARRIER CONFIG_MMC_BCM2835_SDHOST_PIO_DMA_BARRIER
+#else
+#define PIO_DMA_BARRIER 0
+#endif
+
+#define MIN_FREQ 400000
+#define TIMEOUT_VAL 0xE
+#define BCM2835_SDHOST_WRITE_DELAY(f)	(((2 * 1000000) / f) + 1)
+
+#ifndef BCM2708_PERI_BASE
+ #define BCM2708_PERI_BASE 0x20000000
+#endif
+
+/* FIXME: Needs IOMMU support */
+#define BCM2835_VCMMU_SHIFT		(0x7E000000 - BCM2708_PERI_BASE)
+
+
+struct bcm2835_host {
+	spinlock_t		lock;
+
+	void __iomem		*ioaddr;
+	u32			phys_addr;
+
+	struct mmc_host		*mmc;
+
+	u32			timeout;
+
+	int			clock;		/* Current clock speed */
+
+	bool			slow_card;	/* Force 11-bit divisor */
+
+	unsigned int		max_clk;	/* Max possible freq */
+	unsigned int		timeout_clk;	/* Timeout freq (KHz) */
+
+	struct tasklet_struct	finish_tasklet;	/* Tasklet structures */
+
+	struct timer_list	timer;		/* Timer for timeouts */
+
+	struct sg_mapping_iter	sg_miter;	/* SG state for PIO */
+	unsigned int		blocks;		/* remaining PIO blocks */
+
+	int			irq;		/* Device IRQ */
+
+
+	/* 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 */
+	unsigned int			data_complete:1;	/* Data finished before cmd */
+
+	unsigned int			flush_fifo:1;		/* Drain the fifo when finishing */
+
+	unsigned int			use_busy:1;		/* Wait for busy interrupt */
+
+	u32				thread_isr;
+
+	/*DMA part*/
+	struct dma_chan			*dma_chan_rx;		/* DMA channel for reads */
+	struct dma_chan			*dma_chan_tx;		/* DMA channel for writes */
+
+	bool				allow_dma;
+	bool				have_dma;
+	bool				use_dma;
+	/*end of DMA part*/
+
+	int				max_delay;	/* maximum length of time spent waiting */
+	struct timeval			stop_time;	/* when the last stop was issued */
+	u32				delay_after_stop; /* minimum time between stop and subsequent data transfer */
+	u32				overclock_50;	/* frequency to use when 50MHz is requested (in MHz) */
+	u32				max_overclock;	/* Highest reported */
+};
+
+
+static inline void bcm2835_sdhost_write(struct bcm2835_host *host, u32 val, int reg)
+{
+	writel(val, host->ioaddr + reg);
+}
+
+static inline u32 bcm2835_sdhost_read(struct bcm2835_host *host, int reg)
+{
+	return readl(host->ioaddr + reg);
+}
+
+static inline u32 bcm2835_sdhost_read_relaxed(struct bcm2835_host *host, int reg)
+{
+	return readl_relaxed(host->ioaddr + reg);
+}
+
+static void bcm2835_sdhost_dumpregs(struct bcm2835_host *host)
+{
+	pr_info(DRIVER_NAME ": =========== REGISTER DUMP (%s)===========\n",
+		mmc_hostname(host->mmc));
+
+	pr_info(DRIVER_NAME ": SDCMD  0x%08x\n",
+		bcm2835_sdhost_read(host, SDCMD));
+	pr_info(DRIVER_NAME ": SDARG  0x%08x\n",
+		bcm2835_sdhost_read(host, SDARG));
+	pr_info(DRIVER_NAME ": SDTOUT 0x%08x\n",
+		bcm2835_sdhost_read(host, SDTOUT));
+	pr_info(DRIVER_NAME ": SDCDIV 0x%08x\n",
+		bcm2835_sdhost_read(host, SDCDIV));
+	pr_info(DRIVER_NAME ": SDRSP0 0x%08x\n",
+		bcm2835_sdhost_read(host, SDRSP0));
+	pr_info(DRIVER_NAME ": SDRSP1 0x%08x\n",
+		bcm2835_sdhost_read(host, SDRSP1));
+	pr_info(DRIVER_NAME ": SDRSP2 0x%08x\n",
+		bcm2835_sdhost_read(host, SDRSP2));
+	pr_info(DRIVER_NAME ": SDRSP3 0x%08x\n",
+		bcm2835_sdhost_read(host, SDRSP3));
+	pr_info(DRIVER_NAME ": SDHSTS 0x%08x\n",
+		bcm2835_sdhost_read(host, SDHSTS));
+	pr_info(DRIVER_NAME ": SDVDD  0x%08x\n",
+		bcm2835_sdhost_read(host, SDVDD));
+	pr_info(DRIVER_NAME ": SDEDM  0x%08x\n",
+		bcm2835_sdhost_read(host, SDEDM));
+	pr_info(DRIVER_NAME ": SDHCFG 0x%08x\n",
+		bcm2835_sdhost_read(host, SDHCFG));
+	pr_info(DRIVER_NAME ": SDHBCT 0x%08x\n",
+		bcm2835_sdhost_read(host, SDHBCT));
+	pr_info(DRIVER_NAME ": SDHBLC 0x%08x\n",
+		bcm2835_sdhost_read(host, SDHBLC));
+
+	pr_debug(DRIVER_NAME ": ===========================================\n");
+}
+
+
+static void bcm2835_sdhost_set_power(struct bcm2835_host *host, bool on)
+{
+	bcm2835_sdhost_write(host, on ? 1 : 0, SDVDD);
+}
+
+
+static void bcm2835_sdhost_reset(struct bcm2835_host *host)
+{
+	u32 temp;
+
+	pr_debug("bcm2835_sdhost_reset\n");
+
+	bcm2835_sdhost_set_power(host, false);
+
+	bcm2835_sdhost_write(host, 0, SDCMD);
+	bcm2835_sdhost_write(host, 0, SDARG);
+	bcm2835_sdhost_write(host, 0xf00000, SDTOUT);
+	bcm2835_sdhost_write(host, 0, SDCDIV);
+	bcm2835_sdhost_write(host, 0x7f8, SDHSTS); /* Write 1s to clear */
+	bcm2835_sdhost_write(host, 0, SDHCFG);
+	bcm2835_sdhost_write(host, 0, SDHBCT);
+	bcm2835_sdhost_write(host, 0, SDHBLC);
+
+	/* Limit fifo usage due to silicon bug */
+	temp = bcm2835_sdhost_read(host, SDEDM);
+	temp &= ~((SDEDM_THRESHOLD_MASK<<SDEDM_READ_THRESHOLD_SHIFT) |
+		  (SDEDM_THRESHOLD_MASK<<SDEDM_WRITE_THRESHOLD_SHIFT));
+	temp |= (SAFE_READ_THRESHOLD << SDEDM_READ_THRESHOLD_SHIFT) |
+		(SAFE_WRITE_THRESHOLD << SDEDM_WRITE_THRESHOLD_SHIFT);
+	bcm2835_sdhost_write(host, temp, SDEDM);
+	mdelay(10);
+	bcm2835_sdhost_set_power(host, true);
+	mdelay(10);
+	host->clock = 0;
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+	bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+	mmiowb();
+}
+
+static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios);
+
+static void bcm2835_sdhost_init(struct bcm2835_host *host, int soft)
+{
+	pr_debug("bcm2835_sdhost_init(%d)\n", soft);
+
+	/* Set interrupt enables */
+	host->hcfg = SDHCFG_BUSY_IRPT_EN;
+
+	bcm2835_sdhost_reset(host);
+
+	if (soft) {
+		/* force clock reconfiguration */
+		host->clock = 0;
+		bcm2835_sdhost_set_ios(host->mmc, &host->mmc->ios);
+	}
+}
+
+static bool bcm2835_sdhost_is_write_complete(struct bcm2835_host *host)
+{
+	bool write_complete = ((bcm2835_sdhost_read(host, SDEDM) & 0xf) == 1);
+
+	if (!write_complete) {
+		/* Request an IRQ for the last block */
+		host->hcfg |= SDHCFG_BLOCK_IRPT_EN;
+		bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+		if ((bcm2835_sdhost_read(host, SDEDM) & 0xf) == 1) {
+			/* The write has now completed. Disable the interrupt
+			   and clear the status flag */
+			host->hcfg &= ~SDHCFG_BLOCK_IRPT_EN;
+			bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+			bcm2835_sdhost_write(host, SDHSTS_BLOCK_IRPT, SDHSTS);
+			write_complete = true;
+		}
+	}
+
+	return write_complete;
+}
+
+static void bcm2835_sdhost_wait_write_complete(struct bcm2835_host *host)
+{
+	int timediff;
+#ifdef DEBUG
+	static struct timeval start_time;
+	static int max_stall_time = 0;
+	static int total_stall_time = 0;
+	struct timeval before, after;
+
+	do_gettimeofday(&before);
+	if (max_stall_time == 0)
+		start_time = before;
+#endif
+
+	timediff = 0;
+
+	while (1) {
+		u32 edm = bcm2835_sdhost_read(host, SDEDM);
+		if ((edm & 0xf) == 1)
+			break;
+		timediff++;
+		if (timediff > 5000000) {
+#ifdef DEBUG
+			do_gettimeofday(&after);
+			timediff = (after.tv_sec - before.tv_sec)*1000000 +
+				(after.tv_usec - before.tv_usec);
+
+			pr_err(" wait_write_complete - still waiting after %dus\n",
+			       timediff);
+#else
+			pr_err(" wait_write_complete - still waiting after %d retries\n",
+			       timediff);
+#endif
+			bcm2835_sdhost_dumpregs(host);
+			host->data->error = -ETIMEDOUT;
+			return;
+		}
+	}
+
+#ifdef DEBUG
+	do_gettimeofday(&after);
+	timediff = (after.tv_sec - before.tv_sec)*1000000 + (after.tv_usec - before.tv_usec);
+
+	total_stall_time += timediff;
+	if (timediff > max_stall_time)
+		max_stall_time = timediff;
+
+	if ((after.tv_sec - start_time.tv_sec) > 10) {
+		pr_debug(" wait_write_complete - max wait %dus, total %dus\n",
+			 max_stall_time, total_stall_time);
+		start_time = after;
+		max_stall_time = 0;
+		total_stall_time = 0;
+	}
+#endif
+}
+
+static void bcm2835_sdhost_finish_data(struct bcm2835_host *host);
+
+static void bcm2835_sdhost_dma_complete(void *param)
+{
+	struct bcm2835_host *host = param;
+	struct dma_chan *dma_chan;
+	unsigned long flags;
+	u32 dir_data;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	if (host->data) {
+		bool write_complete;
+		if (USE_BLOCK_IRQ)
+			write_complete = bcm2835_sdhost_is_write_complete(host);
+		else {
+			bcm2835_sdhost_wait_write_complete(host);
+			write_complete = true;
+		}
+		pr_debug("dma_complete() - write_complete=%d\n",
+			 write_complete);
+
+		if (write_complete || (host->data->flags & MMC_DATA_READ))
+		{
+			if (write_complete) {
+				dma_chan = host->dma_chan_tx;
+				dir_data = DMA_TO_DEVICE;
+			} else {
+				dma_chan = host->dma_chan_rx;
+				dir_data = DMA_FROM_DEVICE;
+			}
+
+			dma_unmap_sg(dma_chan->device->dev,
+				     host->data->sg, host->data->sg_len,
+				     dir_data);
+
+			bcm2835_sdhost_finish_data(host);
+		}
+	}
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_read_block_pio(struct bcm2835_host *host)
+{
+	unsigned long flags;
+	size_t blksize, len;
+	u32 *buf;
+
+	blksize = host->data->blksz;
+
+	local_irq_save(flags);
+
+	while (blksize) {
+		if (!sg_miter_next(&host->sg_miter))
+			BUG();
+
+		len = min(host->sg_miter.length, blksize);
+		BUG_ON(len % 4);
+
+		blksize -= len;
+		host->sg_miter.consumed = len;
+
+		buf = (u32 *)host->sg_miter.addr;
+
+		while (len) {
+			while (1) {
+				u32 hsts;
+				hsts = bcm2835_sdhost_read(host, SDHSTS);
+				if (hsts & SDHSTS_DATA_FLAG)
+					break;
+
+				if (hsts & SDHSTS_ERROR_MASK) {
+					pr_err("%s: Transfer error - HSTS %x, HBCT %x - %x left\n",
+					       mmc_hostname(host->mmc),
+					       hsts,
+					       bcm2835_sdhost_read(host, SDHBCT),
+					       blksize + len);
+					if (hsts & SDHSTS_REW_TIME_OUT)
+						host->data->error = -ETIMEDOUT;
+					else if (hsts & (SDHSTS_CRC16_ERROR ||
+						    SDHSTS_CRC7_ERROR))
+						host->data->error = -EILSEQ;
+					else {
+						pr_err("%s: unexpected data error\n",
+						       mmc_hostname(host->mmc));
+						bcm2835_sdhost_dumpregs(host);
+						host->cmd->error = -EIO;
+					}
+				}
+			}
+
+			*(buf++) = bcm2835_sdhost_read(host, SDDATA);
+			len -= 4;
+		}
+	}
+
+	sg_miter_stop(&host->sg_miter);
+
+	local_irq_restore(flags);
+}
+
+static void bcm2835_sdhost_write_block_pio(struct bcm2835_host *host)
+{
+	unsigned long flags;
+	size_t blksize, len;
+	u32 *buf;
+
+	blksize = host->data->blksz;
+
+	local_irq_save(flags);
+
+	while (blksize) {
+		if (!sg_miter_next(&host->sg_miter))
+			BUG();
+
+		len = min(host->sg_miter.length, blksize);
+		BUG_ON(len % 4);
+
+		blksize -= len;
+		host->sg_miter.consumed = len;
+
+		buf = host->sg_miter.addr;
+
+		while (len) {
+			while (!(bcm2835_sdhost_read(host, SDHSTS) & SDHSTS_DATA_FLAG))
+				continue;
+			bcm2835_sdhost_write(host, *(buf++), SDDATA);
+			len -= 4;
+		}
+	}
+
+	sg_miter_stop(&host->sg_miter);
+
+	local_irq_restore(flags);
+}
+
+
+static void bcm2835_sdhost_transfer_pio(struct bcm2835_host *host)
+{
+	BUG_ON(!host->data);
+
+	if (host->data->flags & MMC_DATA_READ)
+		bcm2835_sdhost_read_block_pio(host);
+	else
+		bcm2835_sdhost_write_block_pio(host);
+}
+
+
+static void bcm2835_sdhost_transfer_dma(struct bcm2835_host *host)
+{
+	u32 len, dir_data, dir_slave;
+	struct dma_async_tx_descriptor *desc = NULL;
+	struct dma_chan *dma_chan;
+
+	pr_debug("bcm2835_sdhost_transfer_dma()\n");
+
+	WARN_ON(!host->data);
+
+	if (!host->data)
+		return;
+
+	if (host->data->flags & MMC_DATA_READ) {
+		dma_chan = host->dma_chan_rx;
+		dir_data = DMA_FROM_DEVICE;
+		dir_slave = DMA_DEV_TO_MEM;
+	} else {
+		dma_chan = host->dma_chan_tx;
+		dir_data = DMA_TO_DEVICE;
+		dir_slave = DMA_MEM_TO_DEV;
+	}
+
+	BUG_ON(!dma_chan->device);
+	BUG_ON(!dma_chan->device->dev);
+	BUG_ON(!host->data->sg);
+
+	len = dma_map_sg(dma_chan->device->dev, host->data->sg,
+			 host->data->sg_len, dir_data);
+	if (len > 0) {
+		desc = dmaengine_prep_slave_sg(dma_chan, host->data->sg,
+					       len, dir_slave,
+					       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	} else {
+		dev_err(mmc_dev(host->mmc), "dma_map_sg returned zero length\n");
+	}
+	if (desc) {
+		desc->callback = bcm2835_sdhost_dma_complete;
+		desc->callback_param = host;
+		dmaengine_submit(desc);
+		dma_async_issue_pending(dma_chan);
+	}
+
+}
+
+
+static void bcm2835_sdhost_set_transfer_irqs(struct bcm2835_host *host)
+{
+	u32 all_irqs = SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN |
+		SDHCFG_BUSY_IRPT_EN;
+	if (host->use_dma)
+		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;
+
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+}
+
+
+static void bcm2835_sdhost_prepare_data(struct bcm2835_host *host, struct mmc_command *cmd)
+{
+	struct mmc_data *data = cmd->data;
+
+	WARN_ON(host->data);
+
+	if (!data)
+		return;
+
+	/* Sanity checks */
+	BUG_ON(data->blksz * data->blocks > 524288);
+	BUG_ON(data->blksz > host->mmc->max_blk_size);
+	BUG_ON(data->blocks > 65535);
+
+	host->data = data;
+	host->data_complete = 0;
+	host->flush_fifo = 0;
+	host->data->bytes_xfered = 0;
+
+	if (!host->use_dma) {
+		int flags;
+
+		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;
+	}
+
+	host->use_dma = host->have_dma && data->blocks > PIO_DMA_BARRIER;
+
+	bcm2835_sdhost_set_transfer_irqs(host);
+
+	bcm2835_sdhost_write(host, data->blksz, SDHBCT);
+	if (host->use_dma)
+		bcm2835_sdhost_write(host, data->blocks, SDHBLC);
+
+	BUG_ON(!host->data);
+}
+
+
+void bcm2835_sdhost_send_command(struct bcm2835_host *host, struct mmc_command *cmd)
+{
+	u32 sdcmd;
+	unsigned long timeout;
+
+	WARN_ON(host->cmd);
+
+	if (1) {
+		pr_debug("bcm2835_sdhost_send_command: %08x %08x (flags %x)\n",
+			 cmd->opcode, cmd->arg, (cmd->flags & 0xff) | (cmd->data ? cmd->data->flags : 0));
+		if (cmd->data)
+			pr_debug("bcm2835_sdhost_send_command: %s %d*%x\n",
+				 (cmd->data->flags & MMC_DATA_READ) ?
+				 "read" : "write", cmd->data->blocks,
+				 cmd->data->blksz);
+	}
+
+	/* Wait max 10 ms */
+	timeout = 1000;
+
+	while (bcm2835_sdhost_read(host, SDCMD) & SDCMD_NEW_FLAG) {
+		if (timeout == 0) {
+			pr_err("%s: Previous command never completed.\n",
+				mmc_hostname(host->mmc));
+			bcm2835_sdhost_dumpregs(host);
+			cmd->error = -EIO;
+			tasklet_schedule(&host->finish_tasklet);
+			return;
+		}
+		timeout--;
+		udelay(10);
+	}
+
+	if ((1000-timeout)/100 > 1 && (1000-timeout)/100 > host->max_delay) {
+		host->max_delay = (1000-timeout)/100;
+		pr_warning("Warning: SDHost controller hung for %d ms\n", host->max_delay);
+	}
+
+	timeout = jiffies;
+#ifdef CONFIG_ARCH_BCM2835
+	if (!cmd->data && cmd->busy_timeout > 9000)
+		timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
+	else
+#endif
+	timeout += 10 * HZ;
+	mod_timer(&host->timer, timeout);
+
+	host->cmd = cmd;
+
+	bcm2835_sdhost_prepare_data(host, cmd);
+
+	bcm2835_sdhost_write(host, cmd->arg, SDARG);
+
+	if ((cmd->flags & MMC_RSP_136) && (cmd->flags & MMC_RSP_BUSY)) {
+		pr_err("%s: Unsupported response type!\n",
+			mmc_hostname(host->mmc));
+		cmd->error = -EINVAL;
+		tasklet_schedule(&host->finish_tasklet);
+		return;
+	}
+
+	sdcmd = cmd->opcode & SDCMD_CMD_MASK;
+
+	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 = 1;
+		}
+	}
+
+	if (cmd->data) {
+		if (host->delay_after_stop) {
+			struct timeval now;
+			int time_since_stop;
+			do_gettimeofday(&now);
+			time_since_stop = (now.tv_sec - host->stop_time.tv_sec);
+			if (time_since_stop < 2) {
+				/* Possibly less than one second */
+				time_since_stop = time_since_stop * 1000000 +
+					(now.tv_usec - host->stop_time.tv_usec);
+				if (time_since_stop < host->delay_after_stop)
+					udelay(host->delay_after_stop -
+					       time_since_stop);
+			}
+		}
+
+		if (cmd->data->flags & MMC_DATA_WRITE)
+			sdcmd |= SDCMD_WRITE_CMD;
+		if (cmd->data->flags & MMC_DATA_READ)
+			sdcmd |= SDCMD_READ_CMD;
+	}
+
+	bcm2835_sdhost_write(host, sdcmd | SDCMD_NEW_FLAG, SDCMD);
+}
+
+
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host);
+static void bcm2835_sdhost_transfer_complete(struct bcm2835_host *host);
+
+static void bcm2835_sdhost_finish_data(struct bcm2835_host *host)
+{
+	struct mmc_data *data;
+
+	data = host->data;
+	BUG_ON(!data);
+
+	pr_debug("finish_data(error %d, stop %d, sbc %d)\n",
+	       data->error, data->stop ? 1 : 0,
+	       host->mrq->sbc ? 1 : 0);
+
+	host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+
+	if (data->error) {
+		data->bytes_xfered = 0;
+	} else
+		data->bytes_xfered = data->blksz * data->blocks;
+
+	host->data_complete = 1;
+
+	if (host->cmd) {
+		/*
+		 * Data managed to finish before the
+		 * command completed. Make sure we do
+		 * things in the proper order.
+		 */
+		pr_debug("Finished early - HSTS %x\n",
+			 bcm2835_sdhost_read(host, SDHSTS));
+	}
+	else
+		bcm2835_sdhost_transfer_complete(host);
+}
+
+
+static void bcm2835_sdhost_transfer_complete(struct bcm2835_host *host)
+{
+	struct mmc_data *data;
+
+	BUG_ON(host->cmd);
+	BUG_ON(!host->data);
+	BUG_ON(!host->data_complete);
+
+	data = host->data;
+	host->data = NULL;
+
+	pr_debug("transfer_complete(error %d, stop %d)\n",
+	       data->error, data->stop ? 1 : 0);
+
+	if (data->error)
+		/*
+		 * The controller needs a reset of internal state machines
+		 * upon error conditions.
+		 */
+		bcm2835_sdhost_reset(host);
+
+	/*
+	 * Need to send CMD12 if -
+	 * a) open-ended multiblock transfer (no CMD23)
+	 * b) error in multiblock transfer
+	 */
+	if (data->stop &&
+	    (data->error ||
+	     !host->mrq->sbc)) {
+		host->flush_fifo = 1;
+		bcm2835_sdhost_send_command(host, data->stop);
+		if (host->delay_after_stop)
+			do_gettimeofday(&host->stop_time);
+		if (!host->use_busy)
+			bcm2835_sdhost_finish_command(host);
+	} else {
+		tasklet_schedule(&host->finish_tasklet);
+	}
+}
+
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host)
+{
+	u32 sdcmd;
+	int timeout = 1000;
+#ifdef DEBUG
+	struct timeval before, after;
+	int timediff = 0;
+#endif
+
+	pr_debug("finish_command(%x)\n", bcm2835_sdhost_read(host, SDCMD));
+
+	BUG_ON(!host->cmd || !host->mrq);
+
+#ifdef DEBUG
+	do_gettimeofday(&before);
+#endif
+	for (sdcmd = bcm2835_sdhost_read(host, SDCMD);
+	     (sdcmd & SDCMD_NEW_FLAG) && timeout;
+	     timeout--) {
+		if (host->flush_fifo) {
+			while (bcm2835_sdhost_read(host, SDHSTS) &
+			       SDHSTS_DATA_FLAG)
+				(void)bcm2835_sdhost_read(host, SDDATA);
+		}
+		udelay(10);
+		sdcmd = bcm2835_sdhost_read(host, SDCMD);
+	}
+#ifdef DEBUG
+	do_gettimeofday(&after);
+	timediff = (after.tv_sec - before.tv_sec)*1000000 +
+		(after.tv_usec - before.tv_usec);
+
+	pr_debug(" finish_command - waited %dus\n", timediff);
+#endif
+
+	if (timeout == 0) {
+		pr_err("%s: Command never completed.\n",
+		       mmc_hostname(host->mmc));
+		bcm2835_sdhost_dumpregs(host);
+		host->cmd->error = -EIO;
+		tasklet_schedule(&host->finish_tasklet);
+		return;
+	}
+
+	if (host->flush_fifo) {
+		for (timeout = 100;
+		     (bcm2835_sdhost_read(host, SDHSTS) & SDHSTS_DATA_FLAG) && timeout;
+		     timeout--) {
+			(void)bcm2835_sdhost_read(host, SDDATA);
+		}
+		host->flush_fifo = 0;
+		if (timeout == 0) {
+			pr_err("%s: FIFO never drained.\n",
+			       mmc_hostname(host->mmc));
+			bcm2835_sdhost_dumpregs(host);
+			host->cmd->error = -EIO;
+			tasklet_schedule(&host->finish_tasklet);
+			return;
+		}
+	}
+
+	/* Check for errors */
+	if (sdcmd & SDCMD_FAIL_FLAG)
+	{
+		u32 sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+
+		pr_debug("%s: error detected - CMD %x, HSTS %03x, EDM %x\n",
+		       mmc_hostname(host->mmc), sdcmd, sdhsts,
+		       bcm2835_sdhost_read(host, SDEDM));
+
+		if (sdhsts & SDHSTS_CMD_TIME_OUT)
+			host->cmd->error = -ETIMEDOUT;
+		else
+		{
+			pr_err("%s: unexpected command error\n",
+			       mmc_hostname(host->mmc));
+			bcm2835_sdhost_dumpregs(host);
+			host->cmd->error = -EIO;
+		}
+		tasklet_schedule(&host->finish_tasklet);
+		return;
+	}
+
+	if (host->cmd->flags & MMC_RSP_PRESENT) {
+		if (host->cmd->flags & MMC_RSP_136) {
+			int i;
+			for (i = 0; i < 4; i++)
+				host->cmd->resp[3 - i] = bcm2835_sdhost_read(host, SDRSP0 + i*4);
+			pr_debug("bcm2835_sdhost_finish_command: %08x %08x %08x %08x\n",
+				 host->cmd->resp[0], host->cmd->resp[1], host->cmd->resp[2], host->cmd->resp[3]);
+		} else {
+			host->cmd->resp[0] = bcm2835_sdhost_read(host, SDRSP0);
+			pr_debug("bcm2835_sdhost_finish_command: %08x\n",
+				 host->cmd->resp[0]);
+		}
+	}
+
+	host->cmd->error = 0;
+
+	if (host->cmd == host->mrq->sbc) {
+		/* Finished CMD23, now send actual command. */
+		host->cmd = NULL;
+		bcm2835_sdhost_send_command(host, host->mrq->cmd);
+
+		if (host->cmd->data && host->use_dma)
+			/* DMA transfer starts now, PIO starts after irq */
+			bcm2835_sdhost_transfer_dma(host);
+
+		if (!host->use_busy)
+			bcm2835_sdhost_finish_command(host);
+	} else if (host->cmd == host->mrq->stop)
+		/* Finished CMD12 */
+		tasklet_schedule(&host->finish_tasklet);
+	else {
+		/* Processed actual command. */
+		host->cmd = NULL;
+		if (!host->data)
+			tasklet_schedule(&host->finish_tasklet);
+		else if (host->data_complete)
+			bcm2835_sdhost_transfer_complete(host);
+	}
+}
+
+static void bcm2835_sdhost_timeout_timer(unsigned long data)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+
+	host = (struct bcm2835_host *)data;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	if (host->mrq) {
+		pr_err("%s: Timeout waiting for hardware interrupt.\n",
+			mmc_hostname(host->mmc));
+		bcm2835_sdhost_dumpregs(host);
+
+		if (host->data) {
+			host->data->error = -ETIMEDOUT;
+			bcm2835_sdhost_finish_data(host);
+		} else {
+			if (host->cmd)
+				host->cmd->error = -ETIMEDOUT;
+			else
+				host->mrq->cmd->error = -ETIMEDOUT;
+
+			pr_debug("timeout_timer tasklet_schedule\n");
+			tasklet_schedule(&host->finish_tasklet);
+		}
+	}
+
+	mmiowb();
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_enable_sdio_irq_nolock(struct bcm2835_host *host, int enable)
+{
+	if (enable)
+		host->hcfg |= SDHCFG_SDIO_IRPT_EN;
+	else
+		host->hcfg &= ~SDHCFG_SDIO_IRPT_EN;
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+	mmiowb();
+}
+
+static void bcm2835_sdhost_enable_sdio_irq(struct mmc_host *mmc, int enable)
+{
+	struct bcm2835_host *host = mmc_priv(mmc);
+	unsigned long flags;
+
+	pr_debug("bcm2835_sdhost_enable_sdio_irq(%d)\n", enable);
+	spin_lock_irqsave(&host->lock, flags);
+	bcm2835_sdhost_enable_sdio_irq_nolock(host, enable);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static u32 bcm2835_sdhost_busy_irq(struct bcm2835_host *host, u32 intmask)
+{
+	const u32 handled = (SDHSTS_CMD_TIME_OUT | SDHSTS_CRC16_ERROR |
+			     SDHSTS_CRC7_ERROR | SDHSTS_FIFO_ERROR);
+
+	if (!host->cmd) {
+		pr_err("%s: Got command busy interrupt 0x%08x even "
+			"though no command operation was in progress.\n",
+			mmc_hostname(host->mmc), (unsigned)intmask);
+		bcm2835_sdhost_dumpregs(host);
+		return 0;
+	}
+
+	if (!host->use_busy) {
+		pr_err("%s: Got command busy interrupt 0x%08x even "
+			"though not expecting one.\n",
+			mmc_hostname(host->mmc), (unsigned)intmask);
+		bcm2835_sdhost_dumpregs(host);
+		return 0;
+	}
+	host->use_busy = 0;
+
+	if (intmask & SDHSTS_CMD_TIME_OUT)
+		host->cmd->error = -ETIMEDOUT;
+	else if (intmask & (SDHSTS_CRC16_ERROR | SDHSTS_CRC7_ERROR |
+			SDHSTS_FIFO_ERROR))
+		host->cmd->error = -EILSEQ;
+
+	if (host->cmd->error)
+		tasklet_schedule(&host->finish_tasklet);
+	else
+		bcm2835_sdhost_finish_command(host);
+
+	return handled;
+}
+
+static u32 bcm2835_sdhost_data_irq(struct bcm2835_host *host, u32 intmask)
+{
+	const u32 handled = (SDHSTS_CMD_TIME_OUT | SDHSTS_CRC16_ERROR |
+			     SDHSTS_CRC7_ERROR | SDHSTS_FIFO_ERROR);
+
+	/* 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 0;
+
+	// XXX FIFO_ERROR
+	if (intmask & SDHSTS_CMD_TIME_OUT)
+		host->cmd->error = -ETIMEDOUT;
+	else if ((intmask & (SDHSTS_CRC16_ERROR | SDHSTS_CRC7_ERROR)) &&
+		 ((bcm2835_sdhost_read(host, SDCMD) & SDCMD_CMD_MASK)
+		  != MMC_BUS_TEST_R))
+		host->cmd->error = -EILSEQ;
+
+	/* Use the block interrupt for writes after the first block */
+	if (host->data->flags & MMC_DATA_WRITE) {
+		host->hcfg &= ~(SDHCFG_DATA_IRPT_EN);
+		host->hcfg |= SDHCFG_BLOCK_IRPT_EN;
+		bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+		if (host->data->error)
+			bcm2835_sdhost_finish_data(host);
+		else
+			bcm2835_sdhost_transfer_pio(host);
+	} else {
+		if (!host->data->error) {
+			bcm2835_sdhost_transfer_pio(host);
+			host->blocks--;
+		}
+		if ((host->blocks == 0) || host->data->error)
+			bcm2835_sdhost_finish_data(host);
+	}
+
+	return handled;
+}
+
+static u32 bcm2835_sdhost_block_irq(struct bcm2835_host *host, u32 intmask)
+{
+	struct dma_chan *dma_chan;
+	u32 dir_data;
+	const u32 handled = (SDHSTS_CMD_TIME_OUT | SDHSTS_CRC16_ERROR |
+			     SDHSTS_CRC7_ERROR | SDHSTS_FIFO_ERROR);
+
+	if (!host->data) {
+		pr_err("%s: Got block interrupt 0x%08x even "
+			"though no data operation was in progress.\n",
+			mmc_hostname(host->mmc), (unsigned)intmask);
+		bcm2835_sdhost_dumpregs(host);
+		return handled;
+	}
+
+	if (intmask & SDHSTS_CMD_TIME_OUT)
+		host->cmd->error = -ETIMEDOUT;
+	else if ((intmask & (SDHSTS_CRC16_ERROR | SDHSTS_CRC7_ERROR)) &&
+		 ((bcm2835_sdhost_read(host, SDCMD) & SDCMD_CMD_MASK)
+		  != MMC_BUS_TEST_R))
+		host->cmd->error = -EILSEQ;
+
+	if (!host->use_dma) {
+		BUG_ON(!host->blocks);
+		host->blocks--;
+		if ((host->blocks == 0) || host->data->error)
+			bcm2835_sdhost_finish_data(host);
+		else
+			bcm2835_sdhost_transfer_pio(host);
+	} else if (host->data->flags & MMC_DATA_WRITE) {
+		dma_chan = host->dma_chan_tx;
+		dir_data = DMA_TO_DEVICE;
+		dma_unmap_sg(dma_chan->device->dev,
+			     host->data->sg, host->data->sg_len,
+			     dir_data);
+
+		bcm2835_sdhost_finish_data(host);
+	}
+
+	return handled;
+}
+
+
+static irqreturn_t bcm2835_sdhost_irq(int irq, void *dev_id)
+{
+	irqreturn_t result = IRQ_NONE;
+	struct bcm2835_host *host = dev_id;
+	u32 unexpected = 0, early = 0;
+	int loops = 0;
+#ifndef CONFIG_ARCH_BCM2835
+	int cardint = 0;
+#endif
+	spin_lock(&host->lock);
+
+	for (loops = 0; loops < 1; loops++) {
+		u32 intmask, handled;
+
+		intmask = bcm2835_sdhost_read(host, SDHSTS);
+		handled = intmask & (SDHSTS_BUSY_IRPT |
+				     SDHSTS_BLOCK_IRPT |
+				     SDHSTS_SDIO_IRPT |
+				     SDHSTS_DATA_FLAG);
+		if ((handled == SDHSTS_DATA_FLAG) && // XXX
+		    (loops == 0) && !host->data) {
+			pr_err("%s: sdhost_irq data interrupt 0x%08x even "
+			       "though no data operation was in progress.\n",
+			       mmc_hostname(host->mmc),
+			       (unsigned)intmask);
+
+			bcm2835_sdhost_dumpregs(host);
+		}
+
+		if (!handled)
+			break;
+
+		if (loops)
+			early |= handled;
+
+		result = IRQ_HANDLED;
+
+		/* Clear all interrupts and notifications */
+		bcm2835_sdhost_write(host, intmask, SDHSTS);
+
+		if (intmask & SDHSTS_BUSY_IRPT)
+			handled |= bcm2835_sdhost_busy_irq(host, intmask);
+
+		/* 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))
+			handled |= bcm2835_sdhost_data_irq(host, intmask);
+
+		if (intmask & SDHSTS_BLOCK_IRPT)
+			handled |= bcm2835_sdhost_block_irq(host, intmask);
+
+		if (intmask & SDHSTS_SDIO_IRPT) {
+#ifndef CONFIG_ARCH_BCM2835
+			cardint = 1;
+#else
+			bcm2835_sdhost_enable_sdio_irq_nolock(host, false);
+			host->thread_isr |= SDHSTS_SDIO_IRPT;
+			result = IRQ_WAKE_THREAD;
+#endif
+		}
+
+		unexpected |= (intmask & ~handled);
+	}
+
+	mmiowb();
+
+	spin_unlock(&host->lock);
+
+	if (early)
+		pr_debug("%s: early %x (loops %d)\n", mmc_hostname(host->mmc), early, loops);
+
+	if (unexpected) {
+		pr_err("%s: Unexpected interrupt 0x%08x.\n",
+			   mmc_hostname(host->mmc), unexpected);
+		bcm2835_sdhost_dumpregs(host);
+	}
+
+#ifndef CONFIG_ARCH_BCM2835
+	if (cardint)
+		mmc_signal_sdio_irq(host->mmc);
+#endif
+
+	return result;
+}
+
+#ifdef CONFIG_ARCH_BCM2835
+static irqreturn_t bcm2835_sdhost_thread_irq(int irq, void *dev_id)
+{
+	struct bcm2835_host *host = dev_id;
+	unsigned long flags;
+	u32 isr;
+
+	spin_lock_irqsave(&host->lock, flags);
+	isr = host->thread_isr;
+	host->thread_isr = 0;
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (isr & SDHSTS_SDIO_IRPT) {
+		sdio_run_irqs(host->mmc);
+
+/* Is this necessary? Why re-enable an interrupt which is enabled?
+		spin_lock_irqsave(&host->lock, flags);
+		if (host->flags & SDHSTS_SDIO_IRPT_ENABLED)
+			bcm2835_sdhost_enable_sdio_irq_nolock(host, true);
+		spin_unlock_irqrestore(&host->lock, flags);
+*/
+	}
+
+	return isr ? IRQ_HANDLED : IRQ_NONE;
+}
+#endif
+
+
+
+void bcm2835_sdhost_set_clock(struct bcm2835_host *host, unsigned int clock)
+{
+	int div = 0; /* Initialized for compiler warning */
+	unsigned int input_clock = clock;
+
+	if (host->overclock_50 && (clock == 50000000))
+		clock = host->overclock_50 * 1000000 + 999999;
+
+	/* 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.
+	*/
+
+	host->mmc->actual_clock = 0;
+
+	if (clock < 100000) {
+	    /* Can't stop the clock, but make it as slow as possible
+	     * to show willing
+	     */
+	    host->cdiv = SDCDIV_MAX_CDIV;
+	    bcm2835_sdhost_write(host, host->cdiv, 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);
+	host->mmc->actual_clock = clock;
+
+	if ((clock > input_clock) && (clock > host->max_overclock)) {
+		pr_warn("%s: Overclocking to %dHz\n",
+			mmc_hostname(host->mmc), clock);
+		host->max_overclock = clock;
+	}
+
+	host->cdiv = div;
+	bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+
+	pr_debug(DRIVER_NAME ": clock=%d -> max_clk=%d, cdiv=%x (actual clock %d)\n",
+		 input_clock, host->max_clk, host->cdiv, host->mmc->actual_clock);
+}
+
+static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+
+	if (1) {
+		struct mmc_command *cmd = mrq->cmd;
+		const char *src = "cmd";
+		BUG_ON(!cmd);
+		pr_debug("bcm2835_sdhost_request: %s %08x %08x (flags %x)\n",
+			 src, cmd->opcode, cmd->arg, cmd->flags);
+		if (cmd->data)
+			pr_debug("bcm2835_sdhost_request: %s %d*%d\n",
+				 (cmd->data->flags & MMC_DATA_READ) ?
+				 "read" : "write", cmd->data->blocks,
+				 cmd->data->blksz);
+	}
+
+	if (mrq->data && !is_power_of_2(mrq->data->blksz)) {
+		pr_err("%s: Unsupported block size (%d bytes)\n",
+		       mmc_hostname(mmc), mrq->data->blksz);
+		mrq->cmd->error = -EINVAL;
+		mmc_request_done(mmc, mrq);
+		return;
+	}
+
+	host = mmc_priv(mmc);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	WARN_ON(host->mrq != NULL);
+
+	host->mrq = mrq;
+
+	if (mrq->sbc)
+		bcm2835_sdhost_send_command(host, mrq->sbc);
+	else
+		bcm2835_sdhost_send_command(host, mrq->cmd);
+
+	mmiowb();
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (!mrq->sbc && mrq->cmd->data && host->use_dma)
+		/* DMA transfer starts now, PIO starts after irq */
+		bcm2835_sdhost_transfer_dma(host);
+
+	if (!host->use_busy)
+		bcm2835_sdhost_finish_command(host);
+}
+
+
+static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+
+	struct bcm2835_host *host = mmc_priv(mmc);
+	unsigned long flags;
+
+	pr_debug("bcm2835_sdhost_set_ios: clock %d, pwr %d, bus_width %d, timing %d, vdd %d, drv_type %d\n",
+	       ios->clock, ios->power_mode, ios->bus_width,
+	       ios->timing, ios->signal_voltage, ios->drv_type);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	if (!ios->clock || ios->clock != host->clock) {
+		bcm2835_sdhost_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;
+
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+
+	mmiowb();
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static int bcm2835_sdhost_multi_io_quirk(struct mmc_card *card,
+					 unsigned int direction,
+					 u32 blk_pos, int blk_size)
+{
+	/* There is a bug in the host controller hardware that makes
+	   reading the final sector of the card as part of a multiple read
+	   problematic. Detect that case and shorten the read accordingly.
+	*/
+	/* csd.capacity is in weird units - convert to sectors */
+	u32 card_sectors = (card->csd.capacity << (card->csd.read_blkbits - 9));
+
+	if ((direction == MMC_DATA_READ) &&
+	    ((blk_pos + blk_size) == card_sectors))
+		blk_size--;
+
+	return blk_size;
+}
+
+
+static struct mmc_host_ops bcm2835_sdhost_ops = {
+	.request = bcm2835_sdhost_request,
+	.set_ios = bcm2835_sdhost_set_ios,
+	.enable_sdio_irq = bcm2835_sdhost_enable_sdio_irq,
+	.multi_io_quirk = bcm2835_sdhost_multi_io_quirk,
+};
+
+
+static void bcm2835_sdhost_tasklet_finish(unsigned long param)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+	struct mmc_request *mrq;
+
+	host = (struct bcm2835_host *)param;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	/*
+	 * If this tasklet gets rescheduled while running, it will
+	 * be run again afterwards but without any active request.
+	 */
+	if (!host->mrq) {
+		spin_unlock_irqrestore(&host->lock, flags);
+		return;
+	}
+
+	del_timer(&host->timer);
+
+	mrq = host->mrq;
+
+	/*
+	 * The controller needs a reset of internal state machines
+	 * upon error conditions.
+	 */
+	if (((mrq->cmd && mrq->cmd->error) ||
+		 (mrq->data && (mrq->data->error ||
+		  (mrq->data->stop && mrq->data->stop->error))))) {
+
+		bcm2835_sdhost_reset(host);
+	}
+
+	host->mrq = NULL;
+	host->cmd = NULL;
+	host->data = NULL;
+
+	mmiowb();
+
+	spin_unlock_irqrestore(&host->lock, flags);
+	mmc_request_done(host->mmc, mrq);
+}
+
+
+
+int bcm2835_sdhost_add_host(struct bcm2835_host *host)
+{
+	struct mmc_host *mmc;
+	struct dma_slave_config cfg;
+	int ret;
+
+	mmc = host->mmc;
+
+	bcm2835_sdhost_reset(host);
+
+	mmc->f_max = host->max_clk;
+	mmc->f_min = host->max_clk / SDCDIV_MAX_CDIV;
+
+	/* SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK */
+	host->timeout_clk = mmc->f_max / 1000;
+#ifdef CONFIG_ARCH_BCM2835
+	mmc->max_busy_timeout = (1 << 27) / host->timeout_clk;
+#endif
+	/* host controller capabilities */
+	mmc->caps |= /* MMC_CAP_SDIO_IRQ |*/ MMC_CAP_4_BIT_DATA |
+		MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED |
+		MMC_CAP_NEEDS_POLL |
+		(ALLOW_CMD23 * MMC_CAP_CMD23);
+
+	spin_lock_init(&host->lock);
+
+	if (host->allow_dma) {
+		if (!host->dma_chan_tx || !host->dma_chan_rx ||
+		    IS_ERR(host->dma_chan_tx) || IS_ERR(host->dma_chan_rx)) {
+			pr_err("%s: Unable to initialise DMA channels. Falling back to PIO\n", DRIVER_NAME);
+			host->have_dma = false;
+		} else {
+			pr_info("DMA channels allocated for the SDHost driver");
+			host->have_dma = true;
+
+			cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+			cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+			cfg.slave_id = 13;		/* DREQ channel */
+
+			cfg.direction = DMA_MEM_TO_DEV;
+			cfg.src_addr = 0;
+			cfg.dst_addr = host->phys_addr + SDDATA;
+			ret = dmaengine_slave_config(host->dma_chan_tx, &cfg);
+
+			cfg.direction = DMA_DEV_TO_MEM;
+			cfg.src_addr = host->phys_addr + SDDATA;
+			cfg.dst_addr = 0;
+			ret = dmaengine_slave_config(host->dma_chan_rx, &cfg);
+		}
+	} else {
+		pr_info("Forcing PIO mode\n");
+		host->have_dma = false;
+	}
+
+	mmc->max_segs = 128;
+	mmc->max_req_size = 524288;
+	mmc->max_seg_size = mmc->max_req_size;
+	mmc->max_blk_size = 512;
+	mmc->max_blk_count =  65535;
+
+	/* report supported voltage ranges */
+	mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
+
+	tasklet_init(&host->finish_tasklet,
+		bcm2835_sdhost_tasklet_finish, (unsigned long)host);
+
+	setup_timer(&host->timer, bcm2835_sdhost_timeout_timer, (unsigned long)host);
+
+	bcm2835_sdhost_init(host, 0);
+#ifndef CONFIG_ARCH_BCM2835
+	ret = request_irq(host->irq, bcm2835_sdhost_irq, 0 /*IRQF_SHARED*/,
+				  mmc_hostname(mmc), host);
+#else
+	ret = request_threaded_irq(host->irq, bcm2835_sdhost_irq, bcm2835_sdhost_thread_irq,
+				   IRQF_SHARED,	mmc_hostname(mmc), host);
+#endif
+	if (ret) {
+		pr_err("%s: Failed to request IRQ %d: %d\n",
+		       mmc_hostname(mmc), host->irq, ret);
+		goto untasklet;
+	}
+
+	mmiowb();
+	mmc_add_host(mmc);
+
+	pr_info("Load BCM2835 SDHost driver\n");
+	if (host->delay_after_stop)
+		pr_info("BCM2835 SDHost: delay_after_stop=%dus\n",
+			host->delay_after_stop);
+
+	return 0;
+
+untasklet:
+	tasklet_kill(&host->finish_tasklet);
+
+	return ret;
+}
+
+static int bcm2835_sdhost_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct clk *clk;
+	struct resource *iomem;
+	struct bcm2835_host *host;
+	struct mmc_host *mmc;
+	int ret;
+
+	pr_debug("bcm2835_sdhost_probe\n");
+	mmc = mmc_alloc_host(sizeof(*host), dev);
+	if (!mmc)
+		return -ENOMEM;
+
+	mmc->ops = &bcm2835_sdhost_ops;
+	host = mmc_priv(mmc);
+	host->mmc = mmc;
+	host->timeout = msecs_to_jiffies(1000);
+	spin_lock_init(&host->lock);
+
+	iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	host->ioaddr = devm_ioremap_resource(dev, iomem);
+	if (IS_ERR(host->ioaddr)) {
+		ret = PTR_ERR(host->ioaddr);
+		goto err;
+	}
+
+	host->phys_addr = iomem->start + BCM2835_VCMMU_SHIFT;
+	pr_debug(" - ioaddr %lx, iomem->start %lx, phys_addr %lx\n",
+		 (unsigned long)host->ioaddr,
+		 (unsigned long)iomem->start,
+		 (unsigned long)host->phys_addr);
+
+	host->allow_dma = ALLOW_DMA;
+
+	if (node) {
+		/* Read any custom properties */
+		of_property_read_u32(node,
+				     "brcm,delay-after-stop",
+				     &host->delay_after_stop);
+		of_property_read_u32(node,
+				     "brcm,overclock-50",
+				     &host->overclock_50);
+		host->allow_dma = ALLOW_DMA &&
+			!of_property_read_bool(node, "brcm,force-pio");
+	}
+
+	if (host->allow_dma) {
+		if (node) {
+			host->dma_chan_tx =
+				dma_request_slave_channel(dev, "tx");
+			host->dma_chan_rx =
+				dma_request_slave_channel(dev, "rx");
+		} else {
+			dma_cap_mask_t mask;
+
+			dma_cap_zero(mask);
+			/* we don't care about the channel, any would work */
+			dma_cap_set(DMA_SLAVE, mask);
+			host->dma_chan_tx =
+				dma_request_channel(mask, NULL, NULL);
+			host->dma_chan_rx =
+				dma_request_channel(mask, NULL, NULL);
+		}
+	}
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "could not get clk\n");
+		ret = PTR_ERR(clk);
+		goto err;
+	}
+
+	host->max_clk = clk_get_rate(clk);
+
+	host->irq = platform_get_irq(pdev, 0);
+	if (host->irq <= 0) {
+		dev_err(dev, "get IRQ failed\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	pr_debug(" - max_clk %lx, irq %d\n",
+		 (unsigned long)host->max_clk,
+		 (int)host->irq);
+
+	if (node)
+		mmc_of_parse(mmc);
+	else
+		mmc->caps |= MMC_CAP_4_BIT_DATA;
+
+	ret = bcm2835_sdhost_add_host(host);
+	if (ret)
+		goto err;
+
+	platform_set_drvdata(pdev, host);
+
+	pr_debug("bcm2835_sdhost_probe -> OK\n");
+
+	return 0;
+
+err:
+	pr_debug("bcm2835_sdhost_probe -> err %d\n", ret);
+	mmc_free_host(mmc);
+
+	return ret;
+}
+
+static int bcm2835_sdhost_remove(struct platform_device *pdev)
+{
+	struct bcm2835_host *host = platform_get_drvdata(pdev);
+
+	pr_debug("bcm2835_sdhost_remove\n");
+
+	mmc_remove_host(host->mmc);
+
+	bcm2835_sdhost_set_power(host, false);
+
+	free_irq(host->irq, host);
+
+	del_timer_sync(&host->timer);
+
+	tasklet_kill(&host->finish_tasklet);
+
+	mmc_free_host(host->mmc);
+	platform_set_drvdata(pdev, NULL);
+
+	pr_debug("bcm2835_sdhost_remove - OK\n");
+	return 0;
+}
+
+
+static const struct of_device_id bcm2835_sdhost_match[] = {
+	{ .compatible = "brcm,bcm2835-sdhost" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bcm2835_sdhost_match);
+
+
+
+static struct platform_driver bcm2835_sdhost_driver = {
+	.probe      = bcm2835_sdhost_probe,
+	.remove     = bcm2835_sdhost_remove,
+	.driver     = {
+		.name		= DRIVER_NAME,
+		.owner		= THIS_MODULE,
+		.of_match_table	= bcm2835_sdhost_match,
+	},
+};
+module_platform_driver(bcm2835_sdhost_driver);
+
+MODULE_ALIAS("platform:sdhost-bcm2835");
+MODULE_DESCRIPTION("BCM2835 SDHost driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Phil Elwell");