From bd668494b65c280e06ba3820fad48260a9087124 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 25 Mar 2015 17:49:47 +0000
Subject: [PATCH 0094/1085] 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.

bcm2835-sdhost: Improve error handling and recovery

1) Expose the hw_reset method to the MMC framework, removing many
   internal calls by the driver.

2) Reduce overclock setting on error.

3) Increase timeout to cope with high capacity cards.

4) Add properties and parameters to control pio_limit and debug.

5) Reduce messages at probe time.

bcm2835-sdhost: Further improve overclock back-off

bcm2835-sdhost: Clear HBLC for PIO mode

Also update pio_limit default in overlay README.

bcm2835-sdhost: Add the ERASE capability

See: https://github.com/raspberrypi/linux/issues/1076

bcm2835-sdhost: Ignore CRC7 for MMC CMD1

It seems that the sdhost interface returns CRC7 errors for CMD1,
which is the MMC-specific SEND_OP_COND. Returning these errors to
the MMC layer causes a downward spiral, but ignoring them seems
to be harmless.

bcm2835-mmc/sdhost: Remove ARCH_BCM2835 differences

The bcm2835-mmc driver (and -sdhost driver that copied from it)
contains code to handle SDIO interrupts in a threaded interrupt
handler rather than waking the MMC framework thread. The change
follows a patch from Russell King that adds the facility as the
preferred way of working.

However, the new code path is only present in ARCH_BCM2835
builds, which I have taken to be a way of testing the waters
rather than making the change across the board; I can't see
any technical reason why it wouldn't be enabled for MACH_BCM270X
builds. So this patch standardises on the ARCH_BCM2835 code,
removing the old code paths.

bcm2835-sdhost: Don't log timeout errors unless debug=1

The MMC card-discovery process generates timeouts. This is
expected behaviour, so reporting it to the user serves no purpose.
Suppress the reporting of timeout errors unless the debug flag
is on.

bcm2835-sdhost: Add workaround for odd behaviour on some cards

For reasons not understood, the sdhost driver fails when reading
sectors very near the end of some SD cards. The problem could
be related to the similar issue that reading the final sector
of any card as part of a multiple read never completes, and the
workaround is an extension of the mechanism introduced to solve
that problem which ensures those sectors are always read singly.

bcm2835-sdhost: Major revision

This is a significant revision of the bcm2835-sdhost driver. It
improves on the original in a number of ways:

1) Through the use of CMD23 for reads it appears to avoid problems
   reading some sectors on certain high speed cards.
2) Better atomicity to prevent crashes.
3) Higher performance.
4) Activity logging included, for easier diagnosis in the event
   of a problem.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Restore ATOMIC flag to PIO sg mapping

Allocation problems have been seen in a wireless driver, and
this is the only change which might have been responsible.

SQUASH: bcm2835-sdhost: Only claim one DMA channel

With both MMC controllers enabled there are few DMA channels left. The
bcm2835-sdhost driver only uses DMA in one direction at a time, so it
doesn't need to claim two channels.

See: https://github.com/raspberrypi/linux/issues/1327

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Workaround for "slow" sectors

Some cards have been seen to cause timeouts after certain sectors are
read. This workaround enforces a minimum delay between the stop after
reading one of those sectors and a subsequent data command.

Using CMD23 (SET_BLOCK_COUNT) avoids this problem, so good cards will
not be penalised by this workaround.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Firmware manages the clock divisor

The bcm2835-sdhost driver hands control of the CDIV clock divisor
register to matching firmware, allowing it to adjust to a changing
core clock. This removes the need to use the performance governor or
to enable io_is_busy on the on-demand governor in order to get the
best SD performance.

N.B. As SD clocks must be an integer divisor of the core clock, it is
possible that the SD clock for "turbo" mode can be different (even
lower) than "normal" mode.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Reset the clock in task context

Since reprogramming the clock can now involve a round-trip to the
firmware it must not be done at atomic context, and a tasklet
is not a task.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Don't exit cmd wait loop on error

The FAIL flag can be set in the CMD register before command processing
is complete, leading to spurious "failed to complete" errors. This has
the effect of promoting harmless CRC7 errors during CMD1 processing
into errors that can delay and even prevent booting.

Also:
1) Convert the last KERN_ERROR message in the register dumping to
   KERN_INFO.
2) Remove an unnecessary reset call from  bcm2835_sdhost_add_host.

See: https://github.com/raspberrypi/linux/pull/1492

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: mmc_card_blockaddr fix

Get the definition of mmc_card_blockaddr from drivers/mmc/core/card.h.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: New timer API

mmc: bcm2835-sdhost: Support underclocking

Support underclocking of the SD bus in two ways:
1. using the max-frequency DT property (which currently has no DT
   parameter), and
2. using the exiting sd_overclock parameter.

The two methods differ slightly - in the former the MMC subsystem is
aware of the underclocking, while in the latter it isn't - but the
end results should be the same.

See: https://github.com/raspberrypi/linux/issues/2350

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

mmc: bcm2835-sdhost: Add include

highmem.h (needed for kmap_atomic) is pulled in by one of the other
include files, but only with some CONFIG settings. Make the inclusion
explicit to cater for cases where the CONFIG setting is absent.

See: https://github.com/raspberrypi/linux/issues/2366

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

mmc/bcm2835-sdhost: Recover from MMC_SEND_EXT_CSD

If the user issues an "mmc extcsd read", the SD controller receives
what it thinks is a SEND_IF_COND command with an unexpected data block.
The resulting operations leave the FSM stuck in READWAIT, a state which
persists until the MMC framework resets the controller, by which point
the root filesystem is likely to have been unmounted.

A less heavyweight solution is to detect the condition and nudge the
FSM by asserting the (self-clearing) FORCE_DATA_MODE bit.

N.B. This workaround was essentially discovered by accident and without
a full understanding the inner workings of the controller, so it is
fortunate that the "fix" only modifies error paths.

See: https://github.com/raspberrypi/linux/issues/2728

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

mmc: bcm2835-sdhost: Fix warnings on arm64

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Allow for sg entries that cross pages

The dma_complete handling code calculates a virtual address for a page
then adds an offset, but if the offset is more than a page and HIGHMEM
is in use then the summed address could be in an unmapped (or just
incorrect) page.

The upstream SDHOST driver allows for this possibility - copy the code
that does so.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Fix DMA channel leak on error/remove

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

mmc: bcm2835-sdhost: Support 64-bit physical addresses

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

bcm2835-sdhost: Replace obsolete struct timeval

struct timeval has been retired due to the impending linux 32-bit tv_sec
rollover (only 18 years to go) - timespec64 is the obvious replacement.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

mmc: sdhost: Pass DT pointer to rpi_firmware_get

Using the rpi_firmware API as intended allows proper reference counting
of the firmware device and means we can remove a downstream patch to
the firmware driver.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

bcm2835-sdhost: Use DT to configure logging

Retrieve the system timer base address directly from DT.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

bcm2835-sdhost: Use phys addresses for slave DMA config

Contrary to what struct snd_dmaengine_dai_dma_data suggests, the
configuration of addresses of DMA slave interfaces should be done in
CPU physical addresses.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 drivers/mmc/host/Kconfig          |   10 +
 drivers/mmc/host/Makefile         |    1 +
 drivers/mmc/host/bcm2835-sdhost.c | 2200 +++++++++++++++++++++++++++++
 3 files changed, 2211 insertions(+)
 create mode 100644 drivers/mmc/host/bcm2835-sdhost.c

--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -34,6 +34,16 @@ 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 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_DEBUG
 	bool "MMC host drivers debugging"
 	depends on MMC != n
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_MMC_SDHCI_MILBEAUT)	+= sdhc
 obj-$(CONFIG_MMC_SDHCI_SPEAR)	+= sdhci-spear.o
 obj-$(CONFIG_MMC_SDHCI_AM654)	+= sdhci_am654.o
 obj-$(CONFIG_MMC_BCM2835_MMC)	+= bcm2835-mmc.o
+obj-$(CONFIG_MMC_BCM2835_SDHOST)	+= bcm2835-sdhost.o
 obj-$(CONFIG_MMC_WBSD)		+= wbsd.o
 obj-$(CONFIG_MMC_AU1X)		+= au1xmmc.o
 obj-$(CONFIG_MMC_ALCOR)	+= alcor.o
--- /dev/null
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -0,0 +1,2200 @@
+/*
+ * BCM2835 SD host driver.
+ *
+ * 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
+ *
+ * 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 FIFO_READ_THRESHOLD     4
+#define FIFO_WRITE_THRESHOLD    4
+#define ALLOW_CMD23_READ        1
+#define ALLOW_CMD23_WRITE       0
+#define ENABLE_LOG              1
+#define SDDATA_FIFO_PIO_BURST   8
+#define CMD_DALLY_US            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/mmc/sdio.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>
+#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+/* For mmc_card_blockaddr */
+#include "../core/card.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_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     (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
+
+#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 USE_CMD23_FLAGS          ((ALLOW_CMD23_READ * MMC_DATA_READ) | \
+				  (ALLOW_CMD23_WRITE * MMC_DATA_WRITE))
+
+#define MHZ 1000000
+
+
+struct bcm2835_host {
+	spinlock_t		lock;
+
+	struct rpi_firmware	*fw;
+
+	void __iomem		*ioaddr;
+	phys_addr_t		bus_addr;
+
+	struct mmc_host		*mmc;
+
+	u32			pio_timeout;	/* In jiffies */
+
+	int			clock;		/* Current clock speed */
+
+	bool			slow_card;	/* Force 11-bit divisor */
+
+	unsigned int		max_clk;	/* Max possible freq */
+
+	struct tasklet_struct	finish_tasklet;	/* Tasklet structures */
+
+	struct work_struct	cmd_wait_wq;	/* Workqueue function */
+
+	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 */
+
+	u32			cmd_quick_poll_retries;
+	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 */
+	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 */
+
+	unsigned int			use_sbc:1;		/* Send CMD23 */
+
+	unsigned int			debug:1;		/* Enable debug output */
+	unsigned int			firmware_sets_cdiv:1;	/* Let the firmware manage the clock */
+	unsigned int			reset_clock:1;		/* Reset the clock fore the next request */
+
+	/*DMA part*/
+	struct dma_chan			*dma_chan_rxtx;		/* DMA channel for reads and writes */
+	struct dma_chan			*dma_chan;		/* Channel in use */
+	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				allow_dma;
+	bool				use_dma;
+	/*end of DMA part*/
+
+	int				max_delay;	/* maximum length of time spent waiting */
+	struct timespec64		stop_time;	/* when the last stop was issued */
+	u32				delay_after_stop; /* minimum time between stop and subsequent data transfer */
+	u32				delay_after_this_stop; /* minimum time between this stop and subsequent data transfer */
+	u32				user_overclock_50; /* User's preferred frequency to use when 50MHz is requested (in MHz) */
+	u32				overclock_50;	/* frequency to use when 50MHz is requested (in MHz) */
+	u32				overclock;	/* Current frequency if overclocked, else zero */
+	u32				pio_limit;	/* Maximum block count for PIO (0 = always DMA) */
+
+	u32				sectors;	/* Cached card size in sectors */
+};
+
+#if ENABLE_LOG
+
+struct log_entry_struct {
+	char event[4];
+	u32 timestamp;
+	u32 param1;
+	u32 param2;
+};
+
+typedef struct log_entry_struct LOG_ENTRY_T;
+
+LOG_ENTRY_T *sdhost_log_buf;
+dma_addr_t sdhost_log_addr;
+static u32 sdhost_log_idx;
+static spinlock_t log_lock;
+static void __iomem *timer_base;
+
+#define LOG_ENTRIES (256*1)
+#define LOG_SIZE (sizeof(LOG_ENTRY_T)*LOG_ENTRIES)
+
+static void log_init(struct device *dev)
+{
+	struct device_node *np;
+
+	spin_lock_init(&log_lock);
+	sdhost_log_buf = dma_alloc_coherent(dev, LOG_SIZE, &sdhost_log_addr,
+					     GFP_KERNEL);
+	if (sdhost_log_buf) {
+		np = of_find_compatible_node(NULL, NULL,
+					     "brcm,bcm2835-system-timer");
+		pr_info("sdhost: log_buf @ %p (%llx)\n",
+			sdhost_log_buf, (u64)sdhost_log_addr);
+		timer_base = of_iomap(np, 0);
+		if (!timer_base)
+			pr_err("sdhost: failed to remap timer\n");
+	}
+	else
+		pr_err("sdhost: failed to allocate log buf\n");
+}
+
+static void log_event_impl(const char *event, u32 param1, u32 param2)
+{
+	if (sdhost_log_buf) {
+		LOG_ENTRY_T *entry;
+		unsigned long flags;
+
+		spin_lock_irqsave(&log_lock, flags);
+
+		entry = sdhost_log_buf + sdhost_log_idx;
+		memcpy(entry->event, event, 4);
+		entry->timestamp = (readl(timer_base + 4) & 0x3fffffff) +
+			(smp_processor_id()<<30);
+		entry->param1 = param1;
+		entry->param2 = param2;
+		sdhost_log_idx = (sdhost_log_idx + 1) % LOG_ENTRIES;
+
+		spin_unlock_irqrestore(&log_lock, flags);
+	}
+}
+
+static void log_dump(void)
+{
+	if (sdhost_log_buf) {
+		LOG_ENTRY_T *entry;
+		unsigned long flags;
+		int idx;
+
+		spin_lock_irqsave(&log_lock, flags);
+
+		idx = sdhost_log_idx;
+		do {
+			entry = sdhost_log_buf + idx;
+			if (entry->event[0] != '\0')
+				pr_info("[%08x] %.4s %x %x\n",
+				       entry->timestamp,
+				       entry->event,
+				       entry->param1,
+				       entry->param2);
+			idx = (idx + 1) % LOG_ENTRIES;
+		} while (idx != sdhost_log_idx);
+
+		spin_unlock_irqrestore(&log_lock, flags);
+	}
+}
+
+#define log_event(event, param1, param2) log_event_impl(event, (u32)(uintptr_t)param1, (u32)(uintptr_t)param2)
+
+#else
+
+#define log_init(x) (void)0
+#define log_event(event, param1, param2) (void)0
+#define log_dump() (void)0
+
+#endif
+
+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_dumpcmd(struct bcm2835_host *host,
+				   struct mmc_command *cmd,
+				   const char *label)
+{
+	if (cmd)
+		pr_info("%s:%c%s op %d arg 0x%x flags 0x%x - resp %08x %08x %08x %08x, err %d\n",
+			mmc_hostname(host->mmc),
+			(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_sdhost_dumpregs(struct bcm2835_host *host)
+{
+	if (host->mrq)
+	{
+		bcm2835_sdhost_dumpcmd(host, host->mrq->sbc, "sbc");
+		bcm2835_sdhost_dumpcmd(host, host->mrq->cmd, "cmd");
+		if (host->mrq->data)
+			pr_info("%s: data blocks %x blksz %x - err %d\n",
+			       mmc_hostname(host->mmc),
+			       host->mrq->data->blocks,
+			       host->mrq->data->blksz,
+			       host->mrq->data->error);
+		bcm2835_sdhost_dumpcmd(host, host->mrq->stop, "stop");
+	}
+
+	pr_info("%s: =========== REGISTER DUMP ===========\n",
+		mmc_hostname(host->mmc));
+
+	pr_info("%s: SDCMD  0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDCMD));
+	pr_info("%s: SDARG  0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDARG));
+	pr_info("%s: SDTOUT 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDTOUT));
+	pr_info("%s: SDCDIV 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDCDIV));
+	pr_info("%s: SDRSP0 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDRSP0));
+	pr_info("%s: SDRSP1 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDRSP1));
+	pr_info("%s: SDRSP2 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDRSP2));
+	pr_info("%s: SDRSP3 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDRSP3));
+	pr_info("%s: SDHSTS 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDHSTS));
+	pr_info("%s: SDVDD  0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDVDD));
+	pr_info("%s: SDEDM  0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDEDM));
+	pr_info("%s: SDHCFG 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDHCFG));
+	pr_info("%s: SDHBCT 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDHBCT));
+	pr_info("%s: SDHBLC 0x%08x\n",
+		mmc_hostname(host->mmc),
+		bcm2835_sdhost_read(host, SDHBLC));
+
+	pr_info("%s: ===========================================\n",
+		mmc_hostname(host->mmc));
+}
+
+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_internal(struct bcm2835_host *host)
+{
+	u32 temp;
+
+	if (host->debug)
+		pr_info("%s: reset\n", mmc_hostname(host->mmc));
+
+	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 |= (FIFO_READ_THRESHOLD << SDEDM_READ_THRESHOLD_SHIFT) |
+		(FIFO_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;
+	host->sectors = 0;
+	bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+	bcm2835_sdhost_write(host, SDCDIV_MAX_CDIV, SDCDIV);
+}
+
+#if 0 // todo fix
+static void bcm2835_sdhost_reset(struct mmc_host *mmc)
+{
+	struct bcm2835_host *host = mmc_priv(mmc);
+	unsigned long flags;
+	spin_lock_irqsave(&host->lock, flags);
+	log_event("RST<", 0, 0);
+
+	bcm2835_sdhost_reset_internal(host);
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+#endif
+
+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_internal(host);
+
+	if (soft) {
+		/* force clock reconfiguration */
+		host->clock = 0;
+		bcm2835_sdhost_set_ios(host->mmc, &host->mmc->ios);
+	}
+}
+
+static void bcm2835_sdhost_wait_transfer_complete(struct bcm2835_host *host)
+{
+	int timediff;
+	u32 alternate_idle;
+	u32 edm;
+
+	alternate_idle = (host->mrq->data->flags & MMC_DATA_READ) ?
+		SDEDM_FSM_READWAIT : SDEDM_FSM_WRITESTART1;
+
+	edm = bcm2835_sdhost_read(host, SDEDM);
+
+	log_event("WTC<", edm, 0);
+
+	timediff = 0;
+
+	while (1) {
+		u32 fsm = edm & SDEDM_FSM_MASK;
+		if ((fsm == SDEDM_FSM_IDENTMODE) ||
+		    (fsm == SDEDM_FSM_DATAMODE))
+			break;
+		if (fsm == alternate_idle) {
+			bcm2835_sdhost_write(host,
+					     edm | SDEDM_FORCE_DATA_MODE,
+					     SDEDM);
+			break;
+		}
+
+		timediff++;
+		if (timediff == 100000) {
+			pr_err("%s: wait_transfer_complete - still waiting after %d retries\n",
+			       mmc_hostname(host->mmc),
+			       timediff);
+			log_dump();
+			bcm2835_sdhost_dumpregs(host);
+			host->mrq->data->error = -ETIMEDOUT;
+			log_event("WTC!", edm, 0);
+			return;
+		}
+		cpu_relax();
+		edm = bcm2835_sdhost_read(host, SDEDM);
+	}
+	log_event("WTC>", edm, 0);
+}
+
+static void bcm2835_sdhost_finish_data(struct bcm2835_host *host);
+
+static void bcm2835_sdhost_dma_complete(void *param)
+{
+	struct bcm2835_host *host = param;
+	struct mmc_data *data = host->data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	log_event("DMA<", host->data, bcm2835_sdhost_read(host, SDHSTS));
+	log_event("DMA ", bcm2835_sdhost_read(host, SDCMD),
+		  bcm2835_sdhost_read(host, SDEDM));
+
+	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) {
+		void *page;
+		u32 *buf;
+
+		if (host->drain_offset & PAGE_MASK) {
+			host->drain_page += host->drain_offset >> PAGE_SHIFT;
+			host->drain_offset &= ~PAGE_MASK;
+		}
+
+		page = kmap_atomic(host->drain_page);
+		buf = page + host->drain_offset;
+
+		while (host->drain_words) {
+			u32 edm = bcm2835_sdhost_read(host, SDEDM);
+			if ((edm >> 4) & 0x1f)
+				*(buf++) = bcm2835_sdhost_read(host,
+							       SDDATA);
+			host->drain_words--;
+		}
+
+		kunmap_atomic(page);
+	}
+
+	bcm2835_sdhost_finish_data(host);
+
+	log_event("DMA>", host->data, 0);
+	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;
+	unsigned long wait_max;
+
+	blksize = host->data->blksz;
+
+	wait_max = jiffies + msecs_to_jiffies(host->pio_timeout);
+
+	local_irq_save(flags);
+
+	while (blksize) {
+		int copy_words;
+		u32 hsts = 0;
+
+		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 = SDDATA_FIFO_PIO_BURST;
+			if (burst_words > copy_words)
+				burst_words = copy_words;
+			edm = bcm2835_sdhost_read(host, SDEDM);
+			words = ((edm >> 4) & 0x1f);
+
+			if (words < burst_words) {
+				int fsm_state = (edm & SDEDM_FSM_MASK);
+				if ((fsm_state != SDEDM_FSM_READDATA) &&
+				    (fsm_state != SDEDM_FSM_READWAIT) &&
+				    (fsm_state != SDEDM_FSM_READCRC)) {
+					hsts = bcm2835_sdhost_read(host,
+								   SDHSTS);
+					pr_info("%s: fsm %x, hsts %x\n",
+					       mmc_hostname(host->mmc),
+					       fsm_state, hsts);
+					if (hsts & SDHSTS_ERROR_MASK)
+						break;
+				}
+
+				if (time_after(jiffies, wait_max)) {
+					pr_err("%s: PIO read timeout - EDM %x\n",
+					       mmc_hostname(host->mmc),
+					       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) {
+				*(buf++) = bcm2835_sdhost_read(host, SDDATA);
+				words--;
+			}
+		}
+
+		if (hsts & SDHSTS_ERROR_MASK)
+			break;
+	}
+
+	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;
+	unsigned long wait_max;
+
+	blksize = host->data->blksz;
+
+	wait_max = jiffies + msecs_to_jiffies(host->pio_timeout);
+
+	local_irq_save(flags);
+
+	while (blksize) {
+		int copy_words;
+		u32 hsts = 0;
+
+		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 = SDDATA_FIFO_PIO_BURST;
+			if (burst_words > copy_words)
+				burst_words = copy_words;
+			edm = bcm2835_sdhost_read(host, SDEDM);
+			words = SDDATA_FIFO_WORDS - ((edm >> 4) & 0x1f);
+
+			if (words < burst_words) {
+				int fsm_state = (edm & SDEDM_FSM_MASK);
+				if ((fsm_state != SDEDM_FSM_WRITEDATA) &&
+				    (fsm_state != SDEDM_FSM_WRITESTART1) &&
+				    (fsm_state != SDEDM_FSM_WRITESTART2)) {
+					hsts = bcm2835_sdhost_read(host,
+								   SDHSTS);
+					pr_info("%s: fsm %x, hsts %x\n",
+					       mmc_hostname(host->mmc),
+					       fsm_state, hsts);
+					if (hsts & SDHSTS_ERROR_MASK)
+						break;
+				}
+
+				if (time_after(jiffies, wait_max)) {
+					pr_err("%s: PIO write timeout - EDM %x\n",
+					       mmc_hostname(host->mmc),
+					       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) {
+				bcm2835_sdhost_write(host, *(buf++), SDDATA);
+				words--;
+			}
+		}
+
+		if (hsts & SDHSTS_ERROR_MASK)
+			break;
+	}
+
+	sg_miter_stop(&host->sg_miter);
+
+	local_irq_restore(flags);
+}
+
+static void bcm2835_sdhost_transfer_pio(struct bcm2835_host *host)
+{
+	u32 sdhsts;
+	bool is_read;
+	BUG_ON(!host->data);
+	log_event("XFP<", host->data, host->blocks);
+
+	is_read = (host->data->flags & MMC_DATA_READ) != 0;
+	if (is_read)
+		bcm2835_sdhost_read_block_pio(host);
+	else
+		bcm2835_sdhost_write_block_pio(host);
+
+	sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+	if (sdhsts & (SDHSTS_CRC16_ERROR |
+		      SDHSTS_CRC7_ERROR |
+		      SDHSTS_FIFO_ERROR)) {
+		pr_err("%s: %s transfer error - HSTS %x\n",
+		       mmc_hostname(host->mmc),
+		       is_read ? "read" : "write",
+		       sdhsts);
+		host->data->error = -EILSEQ;
+	} else if ((sdhsts & (SDHSTS_CMD_TIME_OUT |
+			      SDHSTS_REW_TIME_OUT))) {
+		pr_err("%s: %s timeout error - HSTS %x\n",
+		       mmc_hostname(host->mmc),
+		       is_read ? "read" : "write",
+		       sdhsts);
+		host->data->error = -ETIMEDOUT;
+	}
+	log_event("XFP>", host->data, host->blocks);
+}
+
+static void bcm2835_sdhost_prepare_dma(struct bcm2835_host *host,
+	struct mmc_data *data)
+{
+	int len, dir_data, dir_slave;
+	struct dma_async_tx_descriptor *desc = NULL;
+	struct dma_chan *dma_chan;
+
+	log_event("PRD<", data, 0);
+	pr_debug("bcm2835_sdhost_prepare_dma()\n");
+
+	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;
+	}
+	log_event("PRD1", dma_chan, 0);
+
+	BUG_ON(!dma_chan->device);
+	BUG_ON(!dma_chan->device->dev);
+	BUG_ON(!data->sg);
+
+	/* 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)) {
+				BUG_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);
+
+	len = dma_map_sg(dma_chan->device->dev, data->sg, data->sg_len,
+			 dir_data);
+
+	log_event("PRD2", len, 0);
+	if (len > 0)
+		desc = dmaengine_prep_slave_sg(dma_chan, data->sg,
+					       len, dir_slave,
+					       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	log_event("PRD3", desc, 0);
+
+	if (desc) {
+		desc->callback = bcm2835_sdhost_dma_complete;
+		desc->callback_param = host;
+		host->dma_desc = desc;
+		host->dma_chan = dma_chan;
+		host->dma_dir = dir_data;
+	}
+	log_event("PDM>", data, 0);
+}
+
+static void bcm2835_sdhost_start_dma(struct bcm2835_host *host)
+{
+	log_event("SDMA", host->data, host->dma_chan);
+	dmaengine_submit(host->dma_desc);
+	dma_async_issue_pending(host->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->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;
+
+	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);
+
+	host->data = 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_complete = 0;
+	host->flush_fifo = 0;
+	host->data->bytes_xfered = 0;
+
+	if (!host->sectors && host->mmc->card) {
+		struct mmc_card *card = host->mmc->card;
+		if (!mmc_card_sd(card) && mmc_card_blockaddr(card)) {
+			/*
+			 * The EXT_CSD sector count is in number of 512 byte
+			 * sectors.
+			 */
+			host->sectors = card->ext_csd.sectors;
+		} else {
+			/*
+			 * The CSD capacity field is in units of read_blkbits.
+			 * set_capacity takes units of 512 bytes.
+			 */
+			host->sectors = card->csd.capacity <<
+				(card->csd.read_blkbits - 9);
+		}
+	}
+
+	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_sdhost_set_transfer_irqs(host);
+
+	bcm2835_sdhost_write(host, data->blksz, SDHBCT);
+	bcm2835_sdhost_write(host, data->blocks, SDHBLC);
+
+	BUG_ON(!host->data);
+}
+
+bool bcm2835_sdhost_send_command(struct bcm2835_host *host,
+				 struct mmc_command *cmd)
+{
+	u32 sdcmd, sdhsts;
+	unsigned long timeout;
+	int delay;
+
+	WARN_ON(host->cmd);
+	log_event("CMD<", cmd->opcode, cmd->arg);
+
+	if (cmd->data)
+		pr_debug("%s: send_command %d 0x%x "
+			 "(flags 0x%x) - %s %d*%d\n",
+			 mmc_hostname(host->mmc),
+			 cmd->opcode, cmd->arg, cmd->flags,
+			 (cmd->data->flags & MMC_DATA_READ) ?
+			 "read" : "write", cmd->data->blocks,
+			 cmd->data->blksz);
+	else
+		pr_debug("%s: send_command %d 0x%x (flags 0x%x)\n",
+			 mmc_hostname(host->mmc),
+			 cmd->opcode, cmd->arg, cmd->flags);
+
+	/* Wait max 100 ms */
+	timeout = 10000;
+
+	while (bcm2835_sdhost_read(host, SDCMD) & SDCMD_NEW_FLAG) {
+		if (timeout == 0) {
+			pr_warn("%s: previous command never completed.\n",
+				mmc_hostname(host->mmc));
+			if (host->debug)
+				bcm2835_sdhost_dumpregs(host);
+			cmd->error = -EILSEQ;
+			tasklet_schedule(&host->finish_tasklet);
+			return false;
+		}
+		timeout--;
+		udelay(10);
+	}
+
+	delay = (10000 - timeout)/100;
+	if (delay > host->max_delay) {
+		host->max_delay = delay;
+		pr_warn("%s: controller hung for %d ms\n",
+			   mmc_hostname(host->mmc),
+			   host->max_delay);
+	}
+
+	timeout = jiffies;
+	if (!cmd->data && cmd->busy_timeout > 9000)
+		timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
+	else
+		timeout += 10 * HZ;
+	mod_timer(&host->timer, timeout);
+
+	host->cmd = cmd;
+
+	/* Clear any error flags */
+	sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+	if (sdhsts & SDHSTS_ERROR_MASK)
+		bcm2835_sdhost_write(host, sdhsts, SDHSTS);
+
+	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 false;
+	}
+
+	bcm2835_sdhost_prepare_data(host, cmd);
+
+	bcm2835_sdhost_write(host, cmd->arg, SDARG);
+
+	sdcmd = cmd->opcode & SDCMD_CMD_MASK;
+
+	host->use_busy = 0;
+	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) {
+		log_event("CMDD", cmd->data->blocks, cmd->data->blksz);
+		if (host->delay_after_this_stop) {
+			struct timespec64 now;
+			int time_since_stop;
+
+			ktime_get_real_ts64(&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_nsec - host->stop_time.tv_nsec)/1000;
+				if (time_since_stop <
+				    host->delay_after_this_stop)
+					udelay(host->delay_after_this_stop -
+					       time_since_stop);
+			}
+		}
+
+		host->delay_after_this_stop = host->delay_after_stop;
+		if ((cmd->data->flags & MMC_DATA_READ) && !host->use_sbc) {
+			/* See if read crosses one of the hazardous sectors */
+			u32 first_blk, last_blk;
+
+			/* Intentionally include the following sector because
+			   without CMD23/SBC the read may run on. */
+			first_blk = host->mrq->cmd->arg;
+			last_blk = first_blk + cmd->data->blocks;
+
+			if (((last_blk >= (host->sectors - 64)) &&
+			     (first_blk <= (host->sectors - 64))) ||
+			    ((last_blk >= (host->sectors - 32)) &&
+			     (first_blk <= (host->sectors - 32)))) {
+				host->delay_after_this_stop =
+					max(250u, host->delay_after_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);
+
+	return true;
+}
+
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host,
+					  unsigned long *irq_flags);
+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);
+
+	log_event("FDA<", host->mrq, host->cmd);
+	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);
+
+	data->bytes_xfered = data->error ? 0 : (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);
+	log_event("FDA>", host->mrq, host->cmd);
+}
+
+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;
+
+	log_event("TCM<", data, data->error);
+	pr_debug("transfer_complete(error %d, stop %d)\n",
+	       data->error, data->stop ? 1 : 0);
+
+	/*
+	 * 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_sdhost_send_command(host, host->mrq->stop)) {
+			/* No busy, so poll for completion */
+			if (!host->use_busy)
+				bcm2835_sdhost_finish_command(host, NULL);
+
+			if (host->delay_after_this_stop)
+				ktime_get_real_ts64(&host->stop_time);
+		}
+	} else {
+		bcm2835_sdhost_wait_transfer_complete(host);
+		tasklet_schedule(&host->finish_tasklet);
+	}
+	log_event("TCM>", data, 0);
+}
+
+/* If irq_flags is valid, the caller is in a thread context and is allowed
+   to sleep */
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host,
+					  unsigned long *irq_flags)
+{
+	u32 sdcmd;
+	u32 retries;
+#ifdef DEBUG
+	struct timespec64 before, after;
+	int timediff = 0;
+#endif
+
+	log_event("FCM<", host->mrq, host->cmd);
+	pr_debug("finish_command(%x)\n", bcm2835_sdhost_read(host, SDCMD));
+
+	BUG_ON(!host->cmd || !host->mrq);
+
+	/* Poll quickly at first */
+
+	retries = host->cmd_quick_poll_retries;
+	if (!retries) {
+		/* Work out how many polls take 1us by timing 10us */
+		struct timespec64 start, now;
+		int us_diff;
+
+		retries = 1;
+		do {
+			int i;
+
+			retries *= 2;
+
+			ktime_get_real_ts64(&start);
+
+			for (i = 0; i < retries; i++) {
+				cpu_relax();
+				sdcmd = bcm2835_sdhost_read(host, SDCMD);
+			}
+
+			ktime_get_real_ts64(&now);
+			us_diff = (now.tv_sec - start.tv_sec) * 1000000 +
+				(now.tv_nsec - start.tv_nsec)/1000;
+		} while (us_diff < 10);
+
+		host->cmd_quick_poll_retries = ((retries * us_diff + 9)*CMD_DALLY_US)/10 + 1;
+		retries = 1; // We've already waited long enough this time
+	}
+
+	for (sdcmd = bcm2835_sdhost_read(host, SDCMD);
+	     (sdcmd & SDCMD_NEW_FLAG) && retries;
+	     retries--) {
+		cpu_relax();
+		sdcmd = bcm2835_sdhost_read(host, SDCMD);
+	}
+
+	if (!retries) {
+		unsigned long wait_max;
+
+		if (!irq_flags) {
+			/* Schedule the work */
+			log_event("CWWQ", 0, 0);
+			schedule_work(&host->cmd_wait_wq);
+			return;
+		}
+
+		/* Wait max 100 ms */
+		wait_max = jiffies + msecs_to_jiffies(100);
+		while (time_before(jiffies, wait_max)) {
+			spin_unlock_irqrestore(&host->lock, *irq_flags);
+			usleep_range(1, 10);
+			spin_lock_irqsave(&host->lock, *irq_flags);
+			sdcmd = bcm2835_sdhost_read(host, SDCMD);
+			if (!(sdcmd & SDCMD_NEW_FLAG))
+				break;
+		}
+	}
+
+	/* Check for errors */
+	if (sdcmd & SDCMD_NEW_FLAG) {
+		if (host->debug) {
+			pr_err("%s: command %d never completed.\n",
+			       mmc_hostname(host->mmc), host->cmd->opcode);
+			bcm2835_sdhost_dumpregs(host);
+		}
+		host->cmd->error = -EILSEQ;
+		tasklet_schedule(&host->finish_tasklet);
+		return;
+	} else if (sdcmd & SDCMD_FAIL_FLAG) {
+		u32 sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+
+		/* Clear the errors */
+		bcm2835_sdhost_write(host, SDHSTS_ERROR_MASK, SDHSTS);
+
+		if (host->debug)
+			pr_info("%s: error detected - CMD %x, HSTS %03x, EDM %x\n",
+				mmc_hostname(host->mmc), sdcmd, sdhsts,
+				bcm2835_sdhost_read(host, SDEDM));
+
+		if ((sdhsts & SDHSTS_CRC7_ERROR) &&
+		    (host->cmd->opcode == 1)) {
+			if (host->debug)
+				pr_info("%s: ignoring CRC7 error for CMD1\n",
+					mmc_hostname(host->mmc));
+		} else {
+			u32 edm, fsm;
+
+			if (sdhsts & SDHSTS_CMD_TIME_OUT) {
+				if (host->debug)
+					pr_warn("%s: command %d timeout\n",
+					       mmc_hostname(host->mmc),
+					       host->cmd->opcode);
+				host->cmd->error = -ETIMEDOUT;
+			} else {
+				pr_warn("%s: unexpected command %d error\n",
+				       mmc_hostname(host->mmc),
+				       host->cmd->opcode);
+				host->cmd->error = -EILSEQ;
+			}
+
+			edm = readl(host->ioaddr + SDEDM);
+			fsm = edm & SDEDM_FSM_MASK;
+			if (fsm == SDEDM_FSM_READWAIT ||
+			    fsm == SDEDM_FSM_WRITESTART1)
+				writel(edm | SDEDM_FORCE_DATA_MODE,
+				       host->ioaddr + SDEDM);
+			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("%s: finish_command %08x %08x %08x %08x\n",
+				 mmc_hostname(host->mmc),
+				 host->cmd->resp[0], host->cmd->resp[1], host->cmd->resp[2], host->cmd->resp[3]);
+			log_event("RSP ", host->cmd->resp[0], host->cmd->resp[1]);
+		} else {
+			host->cmd->resp[0] = bcm2835_sdhost_read(host, SDRSP0);
+			pr_debug("%s: finish_command %08x\n",
+				 mmc_hostname(host->mmc),
+				 host->cmd->resp[0]);
+			log_event("RSP ", host->cmd->resp[0], 0);
+		}
+	}
+
+	if (host->cmd == host->mrq->sbc) {
+		/* Finished CMD23, now send actual command. */
+		host->cmd = NULL;
+		if (bcm2835_sdhost_send_command(host, host->mrq->cmd)) {
+			if (host->data && host->dma_desc)
+				/* DMA transfer starts now, PIO starts after irq */
+				bcm2835_sdhost_start_dma(host);
+
+			if (!host->use_busy)
+				bcm2835_sdhost_finish_command(host, NULL);
+		}
+	} 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);
+	}
+	log_event("FCM>", host->mrq, host->cmd);
+}
+
+static void bcm2835_sdhost_timeout(struct timer_list *t)
+{
+	struct bcm2835_host *host = from_timer(host, t, timer);
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	log_event("TIM<", 0, 0);
+
+	if (host->mrq) {
+		pr_err("%s: timeout waiting for hardware interrupt.\n",
+			mmc_hostname(host->mmc));
+		log_dump();
+		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);
+		}
+	}
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_busy_irq(struct bcm2835_host *host, u32 intmask)
+{
+	log_event("IRQB", host->cmd, intmask);
+	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;
+	}
+
+	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;
+	}
+	host->use_busy = 0;
+
+	if (intmask & SDHSTS_ERROR_MASK)
+	{
+		pr_err("sdhost_busy_irq: intmask %x, data %p\n", intmask, host->mrq->data);
+		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;
+
+		if (host->debug) {
+			log_dump();
+			bcm2835_sdhost_dumpregs(host);
+		}
+	}
+	else
+		bcm2835_sdhost_finish_command(host, NULL);
+}
+
+static void bcm2835_sdhost_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. */
+	log_event("IRQD", host->data, intmask);
+	if (!host->data)
+		return;
+
+	if (intmask & (SDHSTS_CRC16_ERROR |
+		       SDHSTS_FIFO_ERROR |
+		       SDHSTS_REW_TIME_OUT)) {
+		if (intmask & (SDHSTS_CRC16_ERROR |
+			       SDHSTS_FIFO_ERROR))
+			host->data->error = -EILSEQ;
+		else
+			host->data->error = -ETIMEDOUT;
+
+		if (host->debug) {
+			log_dump();
+			bcm2835_sdhost_dumpregs(host);
+		}
+	}
+
+	if (host->data->error) {
+		bcm2835_sdhost_finish_data(host);
+	} else 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;
+		bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+		bcm2835_sdhost_transfer_pio(host);
+	} else {
+		bcm2835_sdhost_transfer_pio(host);
+		host->blocks--;
+		if ((host->blocks == 0) || host->data->error)
+			bcm2835_sdhost_finish_data(host);
+	}
+}
+
+static void bcm2835_sdhost_block_irq(struct bcm2835_host *host, u32 intmask)
+{
+	log_event("IRQK", host->data, intmask);
+	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;
+	}
+
+	if (intmask & (SDHSTS_CRC16_ERROR |
+		       SDHSTS_FIFO_ERROR |
+		       SDHSTS_REW_TIME_OUT)) {
+		if (intmask & (SDHSTS_CRC16_ERROR |
+			       SDHSTS_FIFO_ERROR))
+			host->data->error = -EILSEQ;
+		else
+			host->data->error = -ETIMEDOUT;
+
+		if (host->debug) {
+			log_dump();
+			bcm2835_sdhost_dumpregs(host);
+		}
+	}
+
+	if (!host->dma_desc) {
+		BUG_ON(!host->blocks);
+		if (host->data->error || (--host->blocks == 0)) {
+			bcm2835_sdhost_finish_data(host);
+		} else {
+			bcm2835_sdhost_transfer_pio(host);
+		}
+	} else if (host->data->flags & MMC_DATA_WRITE) {
+		bcm2835_sdhost_finish_data(host);
+	}
+}
+
+static irqreturn_t bcm2835_sdhost_irq(int irq, void *dev_id)
+{
+	irqreturn_t result = IRQ_NONE;
+	struct bcm2835_host *host = dev_id;
+	u32 intmask;
+
+	spin_lock(&host->lock);
+
+	intmask = bcm2835_sdhost_read(host, SDHSTS);
+	log_event("IRQ<", intmask, 0);
+
+	bcm2835_sdhost_write(host,
+			     SDHSTS_BUSY_IRPT |
+			     SDHSTS_BLOCK_IRPT |
+			     SDHSTS_SDIO_IRPT |
+			     SDHSTS_DATA_FLAG,
+			     SDHSTS);
+
+	if (intmask & SDHSTS_BLOCK_IRPT) {
+		bcm2835_sdhost_block_irq(host, intmask);
+		result = IRQ_HANDLED;
+	}
+
+	if (intmask & SDHSTS_BUSY_IRPT) {
+		bcm2835_sdhost_busy_irq(host, intmask);
+		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_sdhost_data_irq(host, intmask);
+		result = IRQ_HANDLED;
+	}
+
+	log_event("IRQ>", bcm2835_sdhost_read(host, SDHSTS), 0);
+	spin_unlock(&host->lock);
+
+	return result;
+}
+
+void bcm2835_sdhost_set_clock(struct bcm2835_host *host, unsigned int clock)
+{
+	int div = 0; /* Initialized for compiler warning */
+	unsigned int input_clock = clock;
+	unsigned long flags;
+
+	if (host->debug)
+		pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
+
+	if (host->overclock_50 && (clock == 50*MHZ))
+		clock = host->overclock_50 * MHZ + (MHZ - 1);
+
+	/* 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 (host->firmware_sets_cdiv) {
+		u32 msg[3] = { clock, 0, 0 };
+
+		rpi_firmware_property(host->fw,
+				      RPI_FIRMWARE_SET_SDHOST_CLOCK,
+				      &msg, sizeof(msg));
+
+		clock = max(msg[1], msg[2]);
+		spin_lock_irqsave(&host->lock, flags);
+	} else {
+		spin_lock_irqsave(&host->lock, flags);
+		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);
+			spin_unlock_irqrestore(&host->lock, flags);
+			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->cdiv = div;
+		bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+
+		if (host->debug)
+			pr_info("%s: clock=%d -> max_clk=%d, cdiv=%x "
+				"(actual clock %d)\n",
+				mmc_hostname(host->mmc), input_clock,
+				host->max_clk, host->cdiv,
+				clock);
+	}
+
+	/* Calibrate some delays */
+
+	host->ns_per_fifo_word = (1000000000/clock) *
+		((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
+
+	if (input_clock == 50 * MHZ) {
+		if (clock > input_clock) {
+			/* Save the closest value, to make it easier
+			   to reduce in the event of error */
+			host->overclock_50 = (clock/MHZ);
+
+			if (clock != host->overclock) {
+				pr_info("%s: overclocking to %dHz\n",
+					mmc_hostname(host->mmc), clock);
+				host->overclock = clock;
+			}
+		} else if (host->overclock) {
+			host->overclock = 0;
+			if (clock == 50 * MHZ)
+				pr_warn("%s: cancelling overclock\n",
+					mmc_hostname(host->mmc));
+		}
+	} else if (input_clock == 0) {
+		/* Reset the preferred overclock when the clock is stopped.
+		 * This always happens during initialisation. */
+		host->overclock_50 = host->user_overclock_50;
+		host->overclock = 0;
+	}
+
+	/* Set the timeout to 500ms */
+	bcm2835_sdhost_write(host, clock/2, SDTOUT);
+
+	host->mmc->actual_clock = clock;
+	host->clock = input_clock;
+	host->reset_clock = 0;
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+	u32 edm, fsm;
+
+	host = mmc_priv(mmc);
+
+	if (host->debug) {
+		struct mmc_command *cmd = mrq->cmd;
+		BUG_ON(!cmd);
+		if (cmd->data)
+			pr_info("%s: cmd %d 0x%x (flags 0x%x) - %s %d*%d\n",
+				mmc_hostname(mmc),
+				cmd->opcode, cmd->arg, cmd->flags,
+				(cmd->data->flags & MMC_DATA_READ) ?
+				"read" : "write", cmd->data->blocks,
+				cmd->data->blksz);
+		else
+			pr_info("%s: cmd %d 0x%x (flags 0x%x)\n",
+				mmc_hostname(mmc),
+				cmd->opcode, cmd->arg, cmd->flags);
+	}
+
+	/* 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)) {
+		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;
+	}
+
+	if (host->use_dma && mrq->data &&
+	    (mrq->data->blocks > host->pio_limit))
+		bcm2835_sdhost_prepare_dma(host, mrq->data);
+
+	if (host->reset_clock)
+	    bcm2835_sdhost_set_clock(host, host->clock);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	WARN_ON(host->mrq != NULL);
+	host->mrq = mrq;
+
+	edm = bcm2835_sdhost_read(host, SDEDM);
+	fsm = edm & SDEDM_FSM_MASK;
+
+	log_event("REQ<", mrq, edm);
+	if ((fsm != SDEDM_FSM_IDENTMODE) &&
+	    (fsm != SDEDM_FSM_DATAMODE)) {
+		log_event("REQ!", mrq, edm);
+		if (host->debug) {
+			pr_warn("%s: previous command (%d) not complete (EDM %x)\n",
+			       mmc_hostname(host->mmc),
+			       bcm2835_sdhost_read(host, SDCMD) & SDCMD_CMD_MASK,
+			       edm);
+			log_dump();
+			bcm2835_sdhost_dumpregs(host);
+		}
+		mrq->cmd->error = -EILSEQ;
+		tasklet_schedule(&host->finish_tasklet);
+		spin_unlock_irqrestore(&host->lock, flags);
+		return;
+	}
+
+	host->use_sbc = !!mrq->sbc &&
+		(host->mrq->data->flags & USE_CMD23_FLAGS);
+	if (host->use_sbc) {
+		if (bcm2835_sdhost_send_command(host, mrq->sbc)) {
+			if (!host->use_busy)
+				bcm2835_sdhost_finish_command(host, &flags);
+		}
+	} else if (bcm2835_sdhost_send_command(host, mrq->cmd)) {
+		if (host->data && host->dma_desc)
+			/* DMA transfer starts now, PIO starts after irq */
+			bcm2835_sdhost_start_dma(host);
+
+		if (!host->use_busy)
+			bcm2835_sdhost_finish_command(host, &flags);
+	}
+
+	log_event("CMD ", mrq->cmd->opcode,
+		   mrq->data ? (u32)mrq->data->blksz : 0);
+
+	log_event("REQ>", mrq, 0);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+
+	struct bcm2835_host *host = mmc_priv(mmc);
+	unsigned long flags;
+
+	if (host->debug)
+		pr_info("%s: ios clock %d, pwr %d, bus_width %d, "
+			"timing %d, vdd %d, drv_type %d\n",
+			mmc_hostname(mmc),
+			ios->clock, ios->power_mode, ios->bus_width,
+			ios->timing, ios->signal_voltage, ios->drv_type);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	log_event("IOS<", ios->clock, 0);
+
+	/* 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);
+
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (!ios->clock || ios->clock != host->clock)
+		bcm2835_sdhost_set_clock(host, ios->clock);
+}
+
+static struct mmc_host_ops bcm2835_sdhost_ops = {
+	.request = bcm2835_sdhost_request,
+	.set_ios = bcm2835_sdhost_set_ios,
+// todo:fix	.hw_reset = bcm2835_sdhost_reset,
+};
+
+static void bcm2835_sdhost_cmd_wait_work(struct work_struct *work)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+
+	host = container_of(work, struct bcm2835_host, cmd_wait_wq);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	log_event("CWK<", host->cmd, host->mrq);
+
+	/*
+	 * 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;
+	}
+
+	bcm2835_sdhost_finish_command(host, &flags);
+
+	log_event("CWK>", host->cmd, 0);
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_tasklet_finish(unsigned long param)
+{
+	struct bcm2835_host *host;
+	unsigned long flags;
+	struct mmc_request *mrq;
+	struct dma_chan *terminate_chan = NULL;
+
+	host = (struct bcm2835_host *)param;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	log_event("TSK<", host->mrq, 0);
+	/*
+	 * 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;
+
+	/* Drop the overclock after any data corruption, or after any
+	 * error while overclocked. Ignore errors for status commands,
+	 * as they are likely when a card is ejected. */
+	if (host->overclock) {
+		if ((mrq->cmd && mrq->cmd->error &&
+		     (mrq->cmd->opcode != MMC_SEND_STATUS)) ||
+		    (mrq->data && mrq->data->error) ||
+		    (mrq->stop && mrq->stop->error) ||
+		    (mrq->sbc && mrq->sbc->error)) {
+			host->overclock_50--;
+			pr_warn("%s: reducing overclock due to errors\n",
+				mmc_hostname(host->mmc));
+			host->reset_clock = 1;
+			mrq->cmd->error = -ETIMEDOUT;
+			mrq->cmd->retries = 1;
+		}
+	}
+
+	host->mrq = NULL;
+	host->cmd = NULL;
+	host->data = NULL;
+
+	host->dma_desc = NULL;
+	terminate_chan = host->dma_chan;
+	host->dma_chan = NULL;
+
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (terminate_chan)
+	{
+		int err = dmaengine_terminate_all(terminate_chan);
+		if (err)
+			pr_err("%s: failed to terminate DMA (%d)\n",
+			       mmc_hostname(host->mmc), err);
+	}
+
+	/* The SDHOST block doesn't report any errors for a disconnected
+	   interface. All cards and SDIO devices should report some supported
+	   voltage range, so a zero response to SEND_OP_COND, IO_SEND_OP_COND
+	   or APP_SEND_OP_COND can be treated as an error. */
+	if (((mrq->cmd->opcode == MMC_SEND_OP_COND) ||
+	     (mrq->cmd->opcode == SD_IO_SEND_OP_COND) ||
+	     (mrq->cmd->opcode == SD_APP_OP_COND)) &&
+	    (mrq->cmd->error == 0) &&
+	    (mrq->cmd->resp[0] == 0)) {
+		mrq->cmd->error = -ETIMEDOUT;
+		if (host->debug)
+			pr_info("%s: faking timeout due to zero OCR\n",
+				mmc_hostname(host->mmc));
+	}
+
+	mmc_request_done(host->mmc, mrq);
+	log_event("TSK>", mrq, 0);
+}
+
+int bcm2835_sdhost_add_host(struct bcm2835_host *host)
+{
+	struct mmc_host *mmc;
+	struct dma_slave_config cfg;
+	char pio_limit_string[20];
+	int ret;
+
+	mmc = host->mmc;
+
+	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 =  (~(unsigned int)0)/(mmc->f_max/1000);
+
+	pr_debug("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 |
+		((ALLOW_CMD23_READ|ALLOW_CMD23_WRITE) * MMC_CAP_CMD23);
+
+	spin_lock_init(&host->lock);
+
+	if (host->allow_dma) {
+		if (IS_ERR_OR_NULL(host->dma_chan_rxtx)) {
+			pr_err("%s: unable to initialise DMA channel. "
+			       "Falling back to PIO\n",
+			       mmc_hostname(mmc));
+			host->use_dma = false;
+		} else {
+			cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+			cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+			/* Validate the slave configurations */
+
+			cfg.direction = DMA_MEM_TO_DEV;
+			cfg.src_addr = 0;
+			cfg.dst_addr = host->bus_addr + SDDATA;
+
+			ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
+
+			if (ret == 0) {
+				host->dma_cfg_tx = cfg;
+
+				cfg.direction = DMA_DEV_TO_MEM;
+				cfg.src_addr = host->bus_addr + SDDATA;
+				cfg.dst_addr = 0;
+
+				ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
+			}
+
+			if (ret == 0) {
+				host->dma_cfg_rx = cfg;
+
+				host->use_dma = true;
+			} else {
+				pr_err("%s: unable to configure DMA channel. "
+				       "Falling back to PIO\n",
+				       mmc_hostname(mmc));
+				dma_release_channel(host->dma_chan_rxtx);
+				host->dma_chan_rxtx = NULL;
+				host->use_dma = false;
+			}
+		}
+	} else {
+		host->use_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);
+
+	INIT_WORK(&host->cmd_wait_wq, bcm2835_sdhost_cmd_wait_work);
+
+	timer_setup(&host->timer, bcm2835_sdhost_timeout, 0);
+
+	bcm2835_sdhost_init(host, 0);
+
+	ret = request_irq(host->irq, bcm2835_sdhost_irq, 0 /*IRQF_SHARED*/,
+				  mmc_hostname(mmc), host);
+	if (ret) {
+		pr_err("%s: failed to request IRQ %d: %d\n",
+		       mmc_hostname(mmc), host->irq, ret);
+		goto untasklet;
+	}
+
+	mmc_add_host(mmc);
+
+	pio_limit_string[0] = '\0';
+	if (host->use_dma && (host->pio_limit > 0))
+		sprintf(pio_limit_string, " (>%d)", host->pio_limit);
+	pr_info("%s: %s loaded - DMA %s%s\n",
+		mmc_hostname(mmc), DRIVER_NAME,
+		host->use_dma ? "enabled" : "disabled",
+		pio_limit_string);
+
+	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;
+	u32 msg[3];
+	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->pio_timeout = msecs_to_jiffies(500);
+	host->pio_limit = 1;
+	host->max_delay = 1; /* Warn if over 1ms */
+	host->allow_dma = 1;
+	spin_lock_init(&host->lock);
+
+	host->ioaddr = devm_platform_get_and_ioremap_resource(pdev, 0, &iomem);
+	if (IS_ERR(host->ioaddr)) {
+		ret = PTR_ERR(host->ioaddr);
+		goto err;
+	}
+
+	host->bus_addr = iomem->start;
+
+	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->user_overclock_50);
+		of_property_read_u32(node,
+				     "brcm,pio-limit",
+				     &host->pio_limit);
+		host->allow_dma =
+			!of_property_read_bool(node, "brcm,force-pio");
+		host->debug = of_property_read_bool(node, "brcm,debug");
+	}
+
+	host->dma_chan = NULL;
+	host->dma_desc = NULL;
+
+	/* Formally recognise the other way of disabling DMA */
+	if (host->pio_limit == 0x7fffffff)
+		host->allow_dma = false;
+
+	if (host->allow_dma) {
+		if (node) {
+			host->dma_chan_rxtx =
+				dma_request_slave_channel(dev, "rx-tx");
+			if (!host->dma_chan_rxtx)
+				host->dma_chan_rxtx =
+					dma_request_slave_channel(dev, "tx");
+			if (!host->dma_chan_rxtx)
+				host->dma_chan_rxtx =
+					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_rxtx =
+				dma_request_channel(mask, NULL, NULL);
+		}
+	}
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		if (ret == -EPROBE_DEFER)
+			dev_info(dev, "could not get clk, deferring probe\n");
+		else
+			dev_err(dev, "could not get clk\n");
+		goto err;
+	}
+
+	host->fw = rpi_firmware_get(
+		of_parse_phandle(dev->of_node, "firmware", 0));
+	if (!host->fw) {
+		ret = -EPROBE_DEFER;
+		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);
+
+	log_init(dev);
+
+	if (node)
+		mmc_of_parse(mmc);
+	else
+		mmc->caps |= MMC_CAP_4_BIT_DATA;
+
+	msg[0] = 0;
+	msg[1] = ~0;
+	msg[2] = ~0;
+
+	rpi_firmware_property(host->fw,
+			      RPI_FIRMWARE_SET_SDHOST_CLOCK,
+			      &msg, sizeof(msg));
+
+	host->firmware_sets_cdiv = (msg[1] != ~0);
+
+	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);
+	if (host->fw)
+		rpi_firmware_put(host->fw);
+	if (host->dma_chan_rxtx)
+		dma_release_channel(host->dma_chan_rxtx);
+	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);
+	rpi_firmware_put(host->fw);
+	if (host->dma_chan_rxtx)
+		dma_release_channel(host->dma_chan_rxtx);
+	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");
