/*
 * Synopsys DesignWare Multimedia Card Interface driver
 *  (Based on NXP driver for lpc 31xx)
 *
 * Copyright (C) 2009 NXP Semiconductors
 * Copyright (C) 2009, 2010 Imagination Technologies Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/blkdev.h>
#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/mmc/host.h>
#include <linux/mmc/mmc.h>
#include <linux/mmc/dw_mmc.h>
#include <linux/bitops.h>
#include <linux/regulator/consumer.h>
#include <linux/workqueue.h>
#include <plat/cpu.h>

#include "dw_mmc.h"

/* Common flag combinations */
#define DW_MCI_DATA_ERROR_FLAGS	(SDMMC_INT_DTO | SDMMC_INT_DCRC | \
				 SDMMC_INT_HTO | SDMMC_INT_SBE  | \
				 SDMMC_INT_EBE)
#define DW_MCI_CMD_ERROR_FLAGS	(SDMMC_INT_RTO | SDMMC_INT_RCRC | \
				 SDMMC_INT_RESP_ERR)
#define DW_MCI_ERROR_FLAGS	(DW_MCI_DATA_ERROR_FLAGS | \
				 DW_MCI_CMD_ERROR_FLAGS  | SDMMC_INT_HLE)
#define DW_MCI_SEND_STATUS	1
#define DW_MCI_RECV_STATUS	2
#define DW_MCI_DMA_THRESHOLD	16

#ifdef CONFIG_MMC_DW_IDMAC
struct idmac_desc {
	u32		des0;	/* Control Descriptor */
#define IDMAC_DES0_DIC	BIT(1)
#define IDMAC_DES0_LD	BIT(2)
#define IDMAC_DES0_FD	BIT(3)
#define IDMAC_DES0_CH	BIT(4)
#define IDMAC_DES0_ER	BIT(5)
#define IDMAC_DES0_CES	BIT(30)
#define IDMAC_DES0_OWN	BIT(31)

	u32		des1;	/* Buffer sizes */
#define IDMAC_SET_BUFFER1_SIZE(d, s) \
	((d)->des1 = ((d)->des1 & 0x03ffe000) | ((s) & 0x1fff))

	u32		des2;	/* buffer 1 physical address */

	u32		des3;	/* buffer 2 physical address */
};
#endif /* CONFIG_MMC_DW_IDMAC */

/**
 * struct dw_mci_slot - MMC slot state
 * @mmc: The mmc_host representing this slot.
 * @host: The MMC controller this slot is using.
 * @ctype: Card type for this slot.
 * @mrq: mmc_request currently being processed or waiting to be
 *	processed, or NULL when the slot is idle.
 * @queue_node: List node for placing this node in the @queue list of
 *	&struct dw_mci.
 * @clock: Clock rate configured by set_ios(). Protected by host->lock.
 * @flags: Random state bits associated with the slot.
 * @id: Number of this slot.
 * @last_detect_state: Most recently observed card detect state.
 */
struct dw_mci_slot {
	struct mmc_host		*mmc;
	struct dw_mci		*host;

	u32			ctype;

	struct mmc_request	*mrq;
	struct list_head	queue_node;

	unsigned int		clock;
	unsigned long		flags;
#define DW_MMC_CARD_PRESENT	0
#define DW_MMC_CARD_NEED_INIT	1
	int			id;
	int			last_detect_state;
};

#if defined(CONFIG_DEBUG_FS)
static int dw_mci_req_show(struct seq_file *s, void *v)
{
	struct dw_mci_slot *slot = s->private;
	struct mmc_request *mrq;
	struct mmc_command *cmd;
	struct mmc_command *stop;
	struct mmc_data	*data;

	/* Make sure we get a consistent snapshot */
	spin_lock_bh(&slot->host->lock);
	mrq = slot->mrq;

	if (mrq) {
		cmd = mrq->cmd;
		data = mrq->data;
		stop = mrq->stop;

		if (cmd)
			seq_printf(s,
				   "CMD%u(0x%x) flg %x rsp %x %x %x %x err %d\n",
				   cmd->opcode, cmd->arg, cmd->flags,
				   cmd->resp[0], cmd->resp[1], cmd->resp[2],
				   cmd->resp[2], cmd->error);
		if (data)
			seq_printf(s, "DATA %u / %u * %u flg %x err %d\n",
				   data->bytes_xfered, data->blocks,
				   data->blksz, data->flags, data->error);
		if (stop)
			seq_printf(s,
				   "CMD%u(0x%x) flg %x rsp %x %x %x %x err %d\n",
				   stop->opcode, stop->arg, stop->flags,
				   stop->resp[0], stop->resp[1], stop->resp[2],
				   stop->resp[2], stop->error);
	}

	spin_unlock_bh(&slot->host->lock);

	return 0;
}

static int dw_mci_req_open(struct inode *inode, struct file *file)
{
	return single_open(file, dw_mci_req_show, inode->i_private);
}

static const struct file_operations dw_mci_req_fops = {
	.owner		= THIS_MODULE,
	.open		= dw_mci_req_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int dw_mci_regs_show(struct seq_file *s, void *v)
{
	seq_printf(s, "STATUS:\t0x%08x\n", SDMMC_STATUS);
	seq_printf(s, "RINTSTS:\t0x%08x\n", SDMMC_RINTSTS);
	seq_printf(s, "CMD:\t0x%08x\n", SDMMC_CMD);
	seq_printf(s, "CTRL:\t0x%08x\n", SDMMC_CTRL);
	seq_printf(s, "INTMASK:\t0x%08x\n", SDMMC_INTMASK);
	seq_printf(s, "CLKENA:\t0x%08x\n", SDMMC_CLKENA);

	return 0;
}

static int dw_mci_regs_open(struct inode *inode, struct file *file)
{
	return single_open(file, dw_mci_regs_show, inode->i_private);
}

static const struct file_operations dw_mci_regs_fops = {
	.owner		= THIS_MODULE,
	.open		= dw_mci_regs_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static void dw_mci_init_debugfs(struct dw_mci_slot *slot)
{
	struct mmc_host	*mmc = slot->mmc;
	struct dw_mci *host = slot->host;
	struct dentry *root;
	struct dentry *node;

	root = mmc->debugfs_root;
	if (!root)
		return;

	node = debugfs_create_file("regs", S_IRUSR, root, host,
				   &dw_mci_regs_fops);
	if (!node)
		goto err;

	node = debugfs_create_file("req", S_IRUSR, root, slot,
				   &dw_mci_req_fops);
	if (!node)
		goto err;

	node = debugfs_create_u32("state", S_IRUSR, root, (u32 *)&host->state);
	if (!node)
		goto err;

	node = debugfs_create_x32("pending_events", S_IRUSR, root,
				  (u32 *)&host->pending_events);
	if (!node)
		goto err;

	node = debugfs_create_x32("completed_events", S_IRUSR, root,
				  (u32 *)&host->completed_events);
	if (!node)
		goto err;

	return;

err:
	dev_err(&mmc->class_dev, "failed to initialize debugfs for slot\n");
}
#endif /* defined(CONFIG_DEBUG_FS) */

static void dw_mci_set_timeout(struct dw_mci *host)
{
	/* timeout (maximum) */
	mci_writel(host, TMOUT, 0xffffffff);
}

static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
{
	struct mmc_data	*data;
	u32 cmdr;
	cmd->error = -EINPROGRESS;

	cmdr = cmd->opcode;

	if (cmdr == MMC_STOP_TRANSMISSION)
		cmdr |= SDMMC_CMD_STOP;
	else
		cmdr |= SDMMC_CMD_PRV_DAT_WAIT;

	if (cmd->flags & MMC_RSP_PRESENT) {
		/* We expect a response, so set this bit */
		cmdr |= SDMMC_CMD_RESP_EXP;
		if (cmd->flags & MMC_RSP_136)
			cmdr |= SDMMC_CMD_RESP_LONG;
	}

	if (cmd->flags & MMC_RSP_CRC)
		cmdr |= SDMMC_CMD_RESP_CRC;

	data = cmd->data;
	if (data) {
		cmdr |= SDMMC_CMD_DAT_EXP;
		if (data->flags & MMC_DATA_STREAM)
			cmdr |= SDMMC_CMD_STRM_MODE;
		if (data->flags & MMC_DATA_WRITE)
			cmdr |= SDMMC_CMD_DAT_WR;
	}

	return cmdr;
}

static void dw_mci_start_command(struct dw_mci *host,
				 struct mmc_command *cmd, u32 cmd_flags)
{
	host->cmd = cmd;
	dev_vdbg(&host->dev,
		 "start command: ARGR=0x%08x CMDR=0x%08x\n",
		 cmd->arg, cmd_flags);

	mci_writel(host, CMDARG, cmd->arg);
	wmb();

	mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START);
}

static void send_stop_cmd(struct dw_mci *host, struct mmc_data *data)
{
	dw_mci_start_command(host, data->stop, host->stop_cmdr);
}

/* DMA interface functions */
static void dw_mci_stop_dma(struct dw_mci *host)
{
	if (host->using_dma) {
		host->dma_ops->stop(host);
		host->dma_ops->cleanup(host);
	} else {
		/* Data transfer was stopped by the interrupt handler */
		set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
	}
}

static int dw_mci_get_dma_dir(struct mmc_data *data)
{
	if (data->flags & MMC_DATA_WRITE)
		return DMA_TO_DEVICE;
	else
		return DMA_FROM_DEVICE;
}

#ifdef CONFIG_MMC_DW_IDMAC
static void dw_mci_dma_cleanup(struct dw_mci *host)
{
	struct mmc_data *data = host->data;

	if (data)
		if (!data->host_cookie)
			dma_unmap_sg(&host->dev,
				     data->sg,
				     data->sg_len,
				     dw_mci_get_dma_dir(data));
}

static void dw_mci_idmac_stop_dma(struct dw_mci *host)
{
	u32 temp;

	/* Disable and reset the IDMAC interface */
	temp = mci_readl(host, CTRL);
	temp &= ~SDMMC_CTRL_USE_IDMAC;
	temp |= SDMMC_CTRL_DMA_RESET;
	mci_writel(host, CTRL, temp);

	/* Stop the IDMAC running */
	temp = mci_readl(host, BMOD);
	temp &= ~(SDMMC_IDMAC_ENABLE | SDMMC_IDMAC_FB);
	mci_writel(host, BMOD, temp);
}

static void dw_mci_idmac_complete_dma(struct dw_mci *host)
{
	struct mmc_data *data = host->data;

	dev_vdbg(&host->dev, "DMA complete\n");

	host->dma_ops->cleanup(host);

	/*
	 * If the card was removed, data will be NULL. No point in trying to
	 * send the stop command or waiting for NBUSY in this case.
	 */
	if (data) {
		set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
		tasklet_schedule(&host->tasklet);
	}
}

static void dw_mci_translate_sglist(struct dw_mci *host, struct mmc_data *data,
				    unsigned int sg_len)
{
	int i;
	struct idmac_desc *desc = host->sg_cpu;

	for (i = 0; i < sg_len; i++, desc++) {
		unsigned int length = sg_dma_len(&data->sg[i]);
		u32 mem_addr = sg_dma_address(&data->sg[i]);

		/* Set the OWN bit and disable interrupts for this descriptor */
		desc->des0 = IDMAC_DES0_OWN | IDMAC_DES0_DIC | IDMAC_DES0_CH;

		/* Buffer length */
		IDMAC_SET_BUFFER1_SIZE(desc, length);

		/* Physical address to DMA to/from */
		desc->des2 = mem_addr;
	}

	/* Set first descriptor */
	desc = host->sg_cpu;
	desc->des0 |= IDMAC_DES0_FD;

	/* Set last descriptor */
	desc = host->sg_cpu + (i - 1) * sizeof(struct idmac_desc);
	desc->des0 &= ~(IDMAC_DES0_CH | IDMAC_DES0_DIC);
	desc->des0 |= IDMAC_DES0_LD;

	wmb();
}

static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len)
{
	u32 temp;

	dw_mci_translate_sglist(host, host->data, sg_len);

	/* Select IDMAC interface */
	temp = mci_readl(host, CTRL);
	temp |= SDMMC_CTRL_USE_IDMAC;
	mci_writel(host, CTRL, temp);

	wmb();

	/* Enable the IDMAC */
	temp = mci_readl(host, BMOD);
	temp |= SDMMC_IDMAC_ENABLE | SDMMC_IDMAC_FB;
	mci_writel(host, BMOD, temp);

	/* Start it running */
	mci_writel(host, PLDMND, 1);
}

static int dw_mci_idmac_init(struct dw_mci *host)
{
	struct idmac_desc *p;
	int i;

	/* Number of descriptors in the ring buffer */
	host->ring_size = PAGE_SIZE / sizeof(struct idmac_desc);

	/* Forward link the descriptor list */
	for (i = 0, p = host->sg_cpu; i < host->ring_size - 1; i++, p++)
		p->des3 = host->sg_dma + (sizeof(struct idmac_desc) * (i + 1));

	/* Set the last descriptor as the end-of-ring descriptor */
	p->des3 = host->sg_dma;
	p->des0 = IDMAC_DES0_ER;

	mci_writel(host, BMOD, SDMMC_IDMAC_SWRESET);

	/* Mask out interrupts - get Tx & Rx complete only */
	mci_writel(host, IDINTEN, SDMMC_IDMAC_INT_NI | SDMMC_IDMAC_INT_RI |
		   SDMMC_IDMAC_INT_TI);

	/* Set the descriptor base address */
	mci_writel(host, DBADDR, host->sg_dma);
	return 0;
}

static struct dw_mci_dma_ops dw_mci_idmac_ops = {
	.init = dw_mci_idmac_init,
	.start = dw_mci_idmac_start_dma,
	.stop = dw_mci_idmac_stop_dma,
	.complete = dw_mci_idmac_complete_dma,
	.cleanup = dw_mci_dma_cleanup,
};
#endif /* CONFIG_MMC_DW_IDMAC */

static int dw_mci_pre_dma_transfer(struct dw_mci *host,
				   struct mmc_data *data,
				   bool next)
{
	struct scatterlist *sg;
	unsigned int i, sg_len;

	if (!next && data->host_cookie)
		return data->host_cookie;

	/*
	 * We don't do DMA on "complex" transfers, i.e. with
	 * non-word-aligned buffers or lengths. Also, we don't bother
	 * with all the DMA setup overhead for short transfers.
	 */
	if (data->blocks * data->blksz < DW_MCI_DMA_THRESHOLD)
		return -EINVAL;

	if (data->blksz & 3)
		return -EINVAL;

	for_each_sg(data->sg, sg, data->sg_len, i) {
		if (sg->offset & 3 || sg->length & 3)
			return -EINVAL;
	}

	sg_len = dma_map_sg(&host->dev,
			    data->sg,
			    data->sg_len,
			    dw_mci_get_dma_dir(data));
	if (sg_len == 0)
		return -EINVAL;

	if (next)
		data->host_cookie = sg_len;

	return sg_len;
}

static void dw_mci_pre_req(struct mmc_host *mmc,
			   struct mmc_request *mrq,
			   bool is_first_req)
{
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct mmc_data *data = mrq->data;

	if (!slot->host->use_dma || !data)
		return;

	if (data->host_cookie) {
		data->host_cookie = 0;
		return;
	}

	if (dw_mci_pre_dma_transfer(slot->host, mrq->data, 1) < 0)
		data->host_cookie = 0;
}

static void dw_mci_post_req(struct mmc_host *mmc,
			    struct mmc_request *mrq,
			    int err)
{
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct mmc_data *data = mrq->data;

	if (!slot->host->use_dma || !data)
		return;

	if (data->host_cookie)
		dma_unmap_sg(&slot->host->dev,
			     data->sg,
			     data->sg_len,
			     dw_mci_get_dma_dir(data));
	data->host_cookie = 0;
}

static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
{
	int sg_len;
	u32 temp;

	host->using_dma = 0;

	/* If we don't have a channel, we can't do DMA */
	if (!host->use_dma)
		return -ENODEV;

	sg_len = dw_mci_pre_dma_transfer(host, data, 0);
	if (sg_len < 0) {
		host->dma_ops->stop(host);
		return sg_len;
	}

	host->using_dma = 1;

	dev_vdbg(&host->dev,
		 "sd sg_cpu: %#lx sg_dma: %#lx sg_len: %d\n",
		 (unsigned long)host->sg_cpu, (unsigned long)host->sg_dma,
		 sg_len);

	/* Enable the DMA interface */
	temp = mci_readl(host, CTRL);
	temp |= SDMMC_CTRL_DMA_ENABLE;
	mci_writel(host, CTRL, temp);

	/* Disable RX/TX IRQs, let DMA handle it */
	temp = mci_readl(host, INTMASK);
	temp  &= ~(SDMMC_INT_RXDR | SDMMC_INT_TXDR);
	mci_writel(host, INTMASK, temp);

	host->dma_ops->start(host, sg_len);

	return 0;
}

static void dw_mci_submit_data(struct dw_mci *host, struct mmc_data *data)
{
	u32 temp;

	data->error = -EINPROGRESS;

	WARN_ON(host->data);
	host->sg = NULL;
	host->data = data;

	if (data->flags & MMC_DATA_READ)
		host->dir_status = DW_MCI_RECV_STATUS;
	else
		host->dir_status = DW_MCI_SEND_STATUS;

	if (dw_mci_submit_data_dma(host, data)) {
		int flags = SG_MITER_ATOMIC;
		if (host->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->sg = data->sg;
		host->part_buf_start = 0;
		host->part_buf_count = 0;

		mci_writel(host, RINTSTS, SDMMC_INT_TXDR | SDMMC_INT_RXDR);
		temp = mci_readl(host, INTMASK);
		temp |= SDMMC_INT_TXDR | SDMMC_INT_RXDR;
		mci_writel(host, INTMASK, temp);

		temp = mci_readl(host, CTRL);
		temp &= ~SDMMC_CTRL_DMA_ENABLE;
		mci_writel(host, CTRL, temp);
	}
}

static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
{
	struct dw_mci *host = slot->host;
	unsigned long timeout = jiffies + msecs_to_jiffies(500);
	unsigned int cmd_status = 0;

	mci_writel(host, CMDARG, arg);
	wmb();
	mci_writel(host, CMD, SDMMC_CMD_START | cmd);

	while (time_before(jiffies, timeout)) {
		cmd_status = mci_readl(host, CMD);
		if (!(cmd_status & SDMMC_CMD_START))
			return;
	}
	dev_err(&slot->mmc->class_dev,
		"Timeout sending command (cmd %#x arg %#x status %#x)\n",
		cmd, arg, cmd_status);
}

static void dw_mci_setup_bus(struct dw_mci_slot *slot)
{
	struct dw_mci *host = slot->host;
	u32 div;

	if (slot->clock != host->current_speed) {
		div = host->bus_hz / slot->clock;
		if (host->bus_hz % slot->clock && host->bus_hz > slot->clock)
			/*
			 * move the + 1 after the divide to prevent
			 * over-clocking the card.
			 */
			div += 1;

		div = (host->bus_hz != slot->clock) ? DIV_ROUND_UP(div, 2) : 0;

		dev_info(&slot->mmc->class_dev,
			 "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ"
			 " div = %d)\n", slot->id, host->bus_hz, slot->clock,
			 div ? ((host->bus_hz / div) >> 1) : host->bus_hz, div);

		/* disable clock */
		mci_writel(host, CLKENA, 0);
		mci_writel(host, CLKSRC, 0);

		/* inform CIU */
		mci_send_cmd(slot,
			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);

		/* set clock to desired speed */
		mci_writel(host, CLKDIV, div);

		/* inform CIU */
		mci_send_cmd(slot,
			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);

		/* enable clock */
		mci_writel(host, CLKENA, ((SDMMC_CLKEN_ENABLE |
			   SDMMC_CLKEN_LOW_PWR) << slot->id));

		/* inform CIU */
		mci_send_cmd(slot,
			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);

		host->current_speed = slot->clock;
	}

	/* Set the current slot bus width */
	mci_writel(host, CTYPE, (slot->ctype << slot->id));
}

static void __dw_mci_start_request(struct dw_mci *host,
				   struct dw_mci_slot *slot,
				   struct mmc_command *cmd)
{
	struct mmc_request *mrq;
	struct mmc_data	*data;
	u32 cmdflags;

	mrq = slot->mrq;
	if (host->pdata->select_slot)
		host->pdata->select_slot(slot->id);

	/* Slot specific timing and width adjustment */
	dw_mci_setup_bus(slot);

	host->cur_slot = slot;
	host->mrq = mrq;

	host->pending_events = 0;
	host->completed_events = 0;
	host->data_status = 0;

	data = cmd->data;
	if (data) {
		dw_mci_set_timeout(host);
		mci_writel(host, BYTCNT, data->blksz*data->blocks);
		mci_writel(host, BLKSIZ, data->blksz);
	}

	cmdflags = dw_mci_prepare_command(slot->mmc, cmd);

	/* this is the first command, send the initialization clock */
	if (test_and_clear_bit(DW_MMC_CARD_NEED_INIT, &slot->flags))
		cmdflags |= SDMMC_CMD_INIT;

	if (data) {
		dw_mci_submit_data(host, data);
		wmb();
	}

	dw_mci_start_command(host, cmd, cmdflags);

	if (mrq->stop)
		host->stop_cmdr = dw_mci_prepare_command(slot->mmc, mrq->stop);
}

static void dw_mci_start_request(struct dw_mci *host,
				 struct dw_mci_slot *slot)
{
	struct mmc_request *mrq = slot->mrq;
	struct mmc_command *cmd;

	cmd = mrq->sbc ? mrq->sbc : mrq->cmd;
	__dw_mci_start_request(host, slot, cmd);
}

/* must be called with host->lock held */
static void dw_mci_queue_request(struct dw_mci *host, struct dw_mci_slot *slot,
				 struct mmc_request *mrq)
{
	dev_vdbg(&slot->mmc->class_dev, "queue request: state=%d\n",
		 host->state);

	slot->mrq = mrq;

	if (host->state == STATE_IDLE) {
		host->state = STATE_SENDING_CMD;
		dw_mci_start_request(host, slot);
	} else {
		list_add_tail(&slot->queue_node, &host->queue);
	}
}

static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct dw_mci *host = slot->host;

	WARN_ON(slot->mrq);

	/*
	 * The check for card presence and queueing of the request must be
	 * atomic, otherwise the card could be removed in between and the
	 * request wouldn't fail until another card was inserted.
	 */
	spin_lock_bh(&host->lock);

	if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) {
		spin_unlock_bh(&host->lock);
		mrq->cmd->error = -ENOMEDIUM;
		mmc_request_done(mmc, mrq);
		return;
	}

	dw_mci_queue_request(host, slot, mrq);

	spin_unlock_bh(&host->lock);
}

static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
	struct dw_mci_slot *slot = mmc_priv(mmc);
	u32 regs;

	/* set default 1 bit mode */
	slot->ctype = SDMMC_CTYPE_1BIT;

	switch (ios->bus_width) {
	case MMC_BUS_WIDTH_1:
		slot->ctype = SDMMC_CTYPE_1BIT;
		break;
	case MMC_BUS_WIDTH_4:
		slot->ctype = SDMMC_CTYPE_4BIT;
		break;
	case MMC_BUS_WIDTH_8:
		slot->ctype = SDMMC_CTYPE_8BIT;
		break;
	}

	regs = mci_readl(slot->host, UHS_REG);

	/* DDR mode set */
	if (ios->timing == MMC_TIMING_UHS_DDR50)
		regs |= (0x1 << slot->id) << 16;
	else
		regs &= ~(0x1 << slot->id) << 16;

	mci_writel(slot->host, UHS_REG, regs);

	if (slot->host->pdata->set_io_timing)
		slot->host->pdata->set_io_timing(slot->host, ios->timing);

	if (ios->clock) {
		/*
		 * Use mirror of ios->clock to prevent race with mmc
		 * core ios update when finding the minimum.
		 */
		slot->clock = ios->clock;
	}

	switch (ios->power_mode) {
	case MMC_POWER_UP:
		set_bit(DW_MMC_CARD_NEED_INIT, &slot->flags);
		break;
	default:
		break;
	}
}

static int dw_mci_get_ro(struct mmc_host *mmc)
{
	int read_only;
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct dw_mci_board *brd = slot->host->pdata;

	/* Use platform get_ro function, else try on board write protect */
	if (brd->get_ro)
		read_only = brd->get_ro(slot->id);
	else
		read_only =
			mci_readl(slot->host, WRTPRT) & (1 << slot->id) ? 1 : 0;

	dev_dbg(&mmc->class_dev, "card is %s\n",
		read_only ? "read-only" : "read-write");

	return read_only;
}

static int dw_mci_get_cd(struct mmc_host *mmc)
{
	int present;
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct dw_mci_board *brd = slot->host->pdata;

	/* Use platform get_cd function, else try onboard card detect */
	if (brd->quirks & DW_MCI_QUIRK_BROKEN_CARD_DETECTION)
		present = 1;
	else if (brd->get_cd)
		present = !brd->get_cd(slot->id);
	else
		present = (mci_readl(slot->host, CDETECT) & (1 << slot->id))
			== 0 ? 1 : 0;

	if (present)
		dev_dbg(&mmc->class_dev, "card is present\n");
	else
		dev_dbg(&mmc->class_dev, "card is not present\n");

	return present;
}

static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
{
	struct dw_mci_slot *slot = mmc_priv(mmc);
	struct dw_mci *host = slot->host;
	u32 int_mask;

	/* Enable/disable Slot Specific SDIO interrupt */
	int_mask = mci_readl(host, INTMASK);
	if (enb) {
		mci_writel(host, INTMASK,
			   (int_mask | SDMMC_INT_SDIO(slot->id)));
	} else {
		mci_writel(host, INTMASK,
			   (int_mask & ~SDMMC_INT_SDIO(slot->id)));
	}
}

static const struct mmc_host_ops dw_mci_ops = {
	.request		= dw_mci_request,	//userspace -> fs -> card -> core -> host
	.pre_req		= dw_mci_pre_req,
	.post_req		= dw_mci_post_req,
	.set_ios		= dw_mci_set_ios,	//用来设置电源、时钟等等之类（需要重点关注）
	.get_ro			= dw_mci_get_ro,	//用来判断是否写保护
	.get_cd			= dw_mci_get_cd,	//
	.enable_sdio_irq	= dw_mci_enable_sdio_irq,
};

static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
	__releases(&host->lock)
	__acquires(&host->lock)
{
	struct dw_mci_slot *slot;
	struct mmc_host	*prev_mmc = host->cur_slot->mmc;

	WARN_ON(host->cmd || host->data);

	host->cur_slot->mrq = NULL;
	host->mrq = NULL;
	if (!list_empty(&host->queue)) {
		slot = list_entry(host->queue.next,
				  struct dw_mci_slot, queue_node);
		list_del(&slot->queue_node);
		dev_vdbg(&host->dev, "list not empty: %s is next\n",
			 mmc_hostname(slot->mmc));
		host->state = STATE_SENDING_CMD;
		dw_mci_start_request(host, slot);
	} else {
		dev_vdbg(&host->dev, "list empty\n");
		host->state = STATE_IDLE;
	}

	spin_unlock(&host->lock);
	mmc_request_done(prev_mmc, mrq);
	spin_lock(&host->lock);
}

static void dw_mci_command_complete(struct dw_mci *host, struct mmc_command *cmd)
{
	u32 status = host->cmd_status;

	host->cmd_status = 0;

	/* Read the response from the card (up to 16 bytes) */
	if (cmd->flags & MMC_RSP_PRESENT) {
		if (cmd->flags & MMC_RSP_136) {
			cmd->resp[3] = mci_readl(host, RESP0);
			cmd->resp[2] = mci_readl(host, RESP1);
			cmd->resp[1] = mci_readl(host, RESP2);
			cmd->resp[0] = mci_readl(host, RESP3);
		} else {
			cmd->resp[0] = mci_readl(host, RESP0);
			cmd->resp[1] = 0;
			cmd->resp[2] = 0;
			cmd->resp[3] = 0;
		}
	}

	if (status & SDMMC_INT_RTO)
		cmd->error = -ETIMEDOUT;
	else if ((cmd->flags & MMC_RSP_CRC) && (status & SDMMC_INT_RCRC))
		cmd->error = -EILSEQ;
	else if (status & SDMMC_INT_RESP_ERR)
		cmd->error = -EIO;
	else
		cmd->error = 0;

	if (cmd->error) {
		/* newer ip versions need a delay between retries */
		if (host->quirks & DW_MCI_QUIRK_RETRY_DELAY)
			mdelay(20);

		if (cmd->data) {
			dw_mci_stop_dma(host);
			host->data = NULL;
		}
	}
}

static void dw_mci_tasklet_func(unsigned long priv)
{
	struct dw_mci *host = (struct dw_mci *)priv;
	struct mmc_data	*data;
	struct mmc_command *cmd;
	enum dw_mci_state state;
	enum dw_mci_state prev_state;
	u32 status, ctrl;

	spin_lock(&host->lock);

	state = host->state;
	data = host->data;

	do {
		prev_state = state;

		switch (state) {
		case STATE_IDLE:
			break;

		case STATE_SENDING_CMD:
			if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
						&host->pending_events))
				break;

			cmd = host->cmd;
			host->cmd = NULL;
			set_bit(EVENT_CMD_COMPLETE, &host->completed_events);
			dw_mci_command_complete(host, cmd);
			if (cmd == host->mrq->sbc && !cmd->error) {
				prev_state = state = STATE_SENDING_CMD;
				__dw_mci_start_request(host, host->cur_slot,
						       host->mrq->cmd);
				goto unlock;
			}

			if (!host->mrq->data || cmd->error) {
				dw_mci_request_end(host, host->mrq);
				goto unlock;
			}

			prev_state = state = STATE_SENDING_DATA;
			/* fall through */

		case STATE_SENDING_DATA:
			if (test_and_clear_bit(EVENT_DATA_ERROR,
					       &host->pending_events)) {
				dw_mci_stop_dma(host);
				if (data->stop)
					send_stop_cmd(host, data);
				state = STATE_DATA_ERROR;
				break;
			}

			if (!test_and_clear_bit(EVENT_XFER_COMPLETE,
						&host->pending_events))
				break;

			set_bit(EVENT_XFER_COMPLETE, &host->completed_events);
			prev_state = state = STATE_DATA_BUSY;
			/* fall through */

		case STATE_DATA_BUSY:
			if (!test_and_clear_bit(EVENT_DATA_COMPLETE,
						&host->pending_events))
				break;

			host->data = NULL;
			set_bit(EVENT_DATA_COMPLETE, &host->completed_events);
			status = host->data_status;

			if (status & DW_MCI_DATA_ERROR_FLAGS) {
				if (status & SDMMC_INT_DTO) {
					data->error = -ETIMEDOUT;
				} else if (status & SDMMC_INT_DCRC) {
					data->error = -EILSEQ;
				} else if (status & SDMMC_INT_EBE &&
					   host->dir_status ==
							DW_MCI_SEND_STATUS) {
					/*
					 * No data CRC status was returned.
					 * The number of bytes transferred will
					 * be exaggerated in PIO mode.
					 */
					data->bytes_xfered = 0;
					data->error = -ETIMEDOUT;
				} else {
					dev_err(&host->dev,
						"data FIFO error "
						"(status=%08x)\n",
						status);
					data->error = -EIO;
				}
				/*
				 * After an error, there may be data lingering
				 * in the FIFO, so reset it - doing so
				 * generates a block interrupt, hence setting
				 * the scatter-gather pointer to NULL.
				 */
				sg_miter_stop(&host->sg_miter);
				host->sg = NULL;
				ctrl = mci_readl(host, CTRL);
				ctrl |= SDMMC_CTRL_FIFO_RESET;
				mci_writel(host, CTRL, ctrl);
			} else {
				data->bytes_xfered = data->blocks * data->blksz;
				data->error = 0;
			}

			if (!data->stop) {
				dw_mci_request_end(host, host->mrq);
				goto unlock;
			}

			if (host->mrq->sbc && !data->error) {
				data->stop->error = 0;
				dw_mci_request_end(host, host->mrq);
				goto unlock;
			}

			prev_state = state = STATE_SENDING_STOP;
			if (!data->error)
				send_stop_cmd(host, data);
			/* fall through */

		case STATE_SENDING_STOP:
			if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
						&host->pending_events))
				break;

			host->cmd = NULL;
			dw_mci_command_complete(host, host->mrq->stop);
			dw_mci_request_end(host, host->mrq);
			goto unlock;

		case STATE_DATA_ERROR:
			if (!test_and_clear_bit(EVENT_XFER_COMPLETE,
						&host->pending_events))
				break;

			state = STATE_DATA_BUSY;
			break;
		}
	} while (state != prev_state);

	host->state = state;
unlock:
	spin_unlock(&host->lock);

}

/* push final bytes to part_buf, only use during push */
static void dw_mci_set_part_bytes(struct dw_mci *host, void *buf, int cnt)
{
	memcpy((void *)&host->part_buf, buf, cnt);
	host->part_buf_count = cnt;
}

/* append bytes to part_buf, only use during push */
static int dw_mci_push_part_bytes(struct dw_mci *host, void *buf, int cnt)
{
	cnt = min(cnt, (1 << host->data_shift) - host->part_buf_count);
	memcpy((void *)&host->part_buf + host->part_buf_count, buf, cnt);
	host->part_buf_count += cnt;
	return cnt;
}

/* pull first bytes from part_buf, only use during pull */
static int dw_mci_pull_part_bytes(struct dw_mci *host, void *buf, int cnt)
{
	cnt = min(cnt, (int)host->part_buf_count);
	if (cnt) {
		memcpy(buf, (void *)&host->part_buf + host->part_buf_start,
		       cnt);
		host->part_buf_count -= cnt;
		host->part_buf_start += cnt;
	}
	return cnt;
}

/* pull final bytes from the part_buf, assuming it's just been filled */
static void dw_mci_pull_final_bytes(struct dw_mci *host, void *buf, int cnt)
{
	memcpy(buf, &host->part_buf, cnt);
	host->part_buf_start = cnt;
	host->part_buf_count = (1 << host->data_shift) - cnt;
}

static void dw_mci_push_data16(struct dw_mci *host, void *buf, int cnt)
{
	/* try and push anything in the part_buf */
	if (unlikely(host->part_buf_count)) {
		int len = dw_mci_push_part_bytes(host, buf, cnt);
		buf += len;
		cnt -= len;
		if (!sg_next(host->sg) || host->part_buf_count == 2) {
			mci_writew(host, DATA(host->data_offset),
					host->part_buf16);
			host->part_buf_count = 0;
		}
	}
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x1)) {
		while (cnt >= 2) {
			u16 aligned_buf[64];
			int len = min(cnt & -2, (int)sizeof(aligned_buf));
			int items = len >> 1;
			int i;
			/* memcpy from input buffer into aligned buffer */
			memcpy(aligned_buf, buf, len);
			buf += len;
			cnt -= len;
			/* push data from aligned buffer into fifo */
			for (i = 0; i < items; ++i)
				mci_writew(host, DATA(host->data_offset),
						aligned_buf[i]);
		}
	} else
#endif
	{
		u16 *pdata = buf;
		for (; cnt >= 2; cnt -= 2)
			mci_writew(host, DATA(host->data_offset), *pdata++);
		buf = pdata;
	}
	/* put anything remaining in the part_buf */
	if (cnt) {
		dw_mci_set_part_bytes(host, buf, cnt);
		if (!sg_next(host->sg))
			mci_writew(host, DATA(host->data_offset),
					host->part_buf16);
	}
}

static void dw_mci_pull_data16(struct dw_mci *host, void *buf, int cnt)
{
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x1)) {
		while (cnt >= 2) {
			/* pull data from fifo into aligned buffer */
			u16 aligned_buf[64];
			int len = min(cnt & -2, (int)sizeof(aligned_buf));
			int items = len >> 1;
			int i;
			for (i = 0; i < items; ++i)
				aligned_buf[i] = mci_readw(host,
						DATA(host->data_offset));
			/* memcpy from aligned buffer into output buffer */
			memcpy(buf, aligned_buf, len);
			buf += len;
			cnt -= len;
		}
	} else
#endif
	{
		u16 *pdata = buf;
		for (; cnt >= 2; cnt -= 2)
			*pdata++ = mci_readw(host, DATA(host->data_offset));
		buf = pdata;
	}
	if (cnt) {
		host->part_buf16 = mci_readw(host, DATA(host->data_offset));
		dw_mci_pull_final_bytes(host, buf, cnt);
	}
}

static void dw_mci_push_data32(struct dw_mci *host, void *buf, int cnt)
{
	/* try and push anything in the part_buf */
	if (unlikely(host->part_buf_count)) {
		int len = dw_mci_push_part_bytes(host, buf, cnt);
		buf += len;
		cnt -= len;
		if (!sg_next(host->sg) || host->part_buf_count == 4) {
			mci_writel(host, DATA(host->data_offset),
					host->part_buf32);
			host->part_buf_count = 0;
		}
	}
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x3)) {
		while (cnt >= 4) {
			u32 aligned_buf[32];
			int len = min(cnt & -4, (int)sizeof(aligned_buf));
			int items = len >> 2;
			int i;
			/* memcpy from input buffer into aligned buffer */
			memcpy(aligned_buf, buf, len);
			buf += len;
			cnt -= len;
			/* push data from aligned buffer into fifo */
			for (i = 0; i < items; ++i)
				mci_writel(host, DATA(host->data_offset),
						aligned_buf[i]);
		}
	} else
#endif
	{
		u32 *pdata = buf;
		for (; cnt >= 4; cnt -= 4)
			mci_writel(host, DATA(host->data_offset), *pdata++);
		buf = pdata;
	}
	/* put anything remaining in the part_buf */
	if (cnt) {
		dw_mci_set_part_bytes(host, buf, cnt);
		if (!sg_next(host->sg))
			mci_writel(host, DATA(host->data_offset),
						host->part_buf32);
	}
}

static void dw_mci_pull_data32(struct dw_mci *host, void *buf, int cnt)
{
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x3)) {
		while (cnt >= 4) {
			/* pull data from fifo into aligned buffer */
			u32 aligned_buf[32];
			int len = min(cnt & -4, (int)sizeof(aligned_buf));
			int items = len >> 2;
			int i;
			for (i = 0; i < items; ++i)
				aligned_buf[i] = mci_readl(host,
						DATA(host->data_offset));
			/* memcpy from aligned buffer into output buffer */
			memcpy(buf, aligned_buf, len);
			buf += len;
			cnt -= len;
		}
	} else
#endif
	{
		u32 *pdata = buf;
		for (; cnt >= 4; cnt -= 4)
			*pdata++ = mci_readl(host, DATA(host->data_offset));
		buf = pdata;
	}
	if (cnt) {
		host->part_buf32 = mci_readl(host, DATA(host->data_offset));
		dw_mci_pull_final_bytes(host, buf, cnt);
	}
}

static void dw_mci_push_data64(struct dw_mci *host, void *buf, int cnt)
{
	/* try and push anything in the part_buf */
	if (unlikely(host->part_buf_count)) {
		int len = dw_mci_push_part_bytes(host, buf, cnt);
		buf += len;
		cnt -= len;
		if (!sg_next(host->sg) || host->part_buf_count == 8) {
			mci_writew(host, DATA(host->data_offset),
					host->part_buf);
			host->part_buf_count = 0;
		}
	}
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x7)) {
		while (cnt >= 8) {
			u64 aligned_buf[16];
			int len = min(cnt & -8, (int)sizeof(aligned_buf));
			int items = len >> 3;
			int i;
			/* memcpy from input buffer into aligned buffer */
			memcpy(aligned_buf, buf, len);
			buf += len;
			cnt -= len;
			/* push data from aligned buffer into fifo */
			for (i = 0; i < items; ++i)
				mci_writeq(host, DATA(host->data_offset),
						aligned_buf[i]);
		}
	} else
#endif
	{
		u64 *pdata = buf;
		for (; cnt >= 8; cnt -= 8)
			mci_writeq(host, DATA(host->data_offset), *pdata++);
		buf = pdata;
	}
	/* put anything remaining in the part_buf */
	if (cnt) {
		dw_mci_set_part_bytes(host, buf, cnt);
		if (!sg_next(host->sg))
			mci_writeq(host, DATA(host->data_offset),
					host->part_buf);
	}
}

static void dw_mci_pull_data64(struct dw_mci *host, void *buf, int cnt)
{
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
	if (unlikely((unsigned long)buf & 0x7)) {
		while (cnt >= 8) {
			/* pull data from fifo into aligned buffer */
			u64 aligned_buf[16];
			int len = min(cnt & -8, (int)sizeof(aligned_buf));
			int items = len >> 3;
			int i;
			for (i = 0; i < items; ++i)
				aligned_buf[i] = mci_readq(host,
						DATA(host->data_offset));
			/* memcpy from aligned buffer into output buffer */
			memcpy(buf, aligned_buf, len);
			buf += len;
			cnt -= len;
		}
	} else
#endif
	{
		u64 *pdata = buf;
		for (; cnt >= 8; cnt -= 8)
			*pdata++ = mci_readq(host, DATA(host->data_offset));
		buf = pdata;
	}
	if (cnt) {
		host->part_buf = mci_readq(host, DATA(host->data_offset));
		dw_mci_pull_final_bytes(host, buf, cnt);
	}
}

static void dw_mci_pull_data(struct dw_mci *host, void *buf, int cnt)
{
	int len;

	/* get remaining partial bytes */
	len = dw_mci_pull_part_bytes(host, buf, cnt);
	if (unlikely(len == cnt))
		return;
	buf += len;
	cnt -= len;

	/* get the rest of the data */
	host->pull_data(host, buf, cnt);
}

static void dw_mci_read_data_pio(struct dw_mci *host)
{
	struct sg_mapping_iter *sg_miter = &host->sg_miter;
	void *buf;
	unsigned int offset;
	struct mmc_data	*data = host->data;
	int shift = host->data_shift;
	u32 status;
	unsigned int nbytes = 0, len;
	unsigned int remain, fcnt;

	do {
		if (!sg_miter_next(sg_miter))
			goto done;

		host->sg = sg_miter->__sg;
		buf = sg_miter->addr;
		remain = sg_miter->length;
		offset = 0;

		do {
			fcnt = (SDMMC_GET_FCNT(mci_readl(host, STATUS))
					<< shift) + host->part_buf_count;
			len = min(remain, fcnt);
			if (!len)
				break;
			dw_mci_pull_data(host, (void *)(buf + offset), len);
			offset += len;
			nbytes += len;
			remain -= len;
		} while (remain);
		sg_miter->consumed = offset;

		status = mci_readl(host, MINTSTS);
		mci_writel(host, RINTSTS, SDMMC_INT_RXDR);
		if (status & DW_MCI_DATA_ERROR_FLAGS) {
			host->data_status = status;
			data->bytes_xfered += nbytes;
			sg_miter_stop(sg_miter);
			host->sg = NULL;
			smp_wmb();

			set_bit(EVENT_DATA_ERROR, &host->pending_events);

			tasklet_schedule(&host->tasklet);
			return;
		}
	} while (status & SDMMC_INT_RXDR); /*if the RXDR is ready read again*/
	data->bytes_xfered += nbytes;

	if (!remain) {
		if (!sg_miter_next(sg_miter))
			goto done;
		sg_miter->consumed = 0;
	}
	sg_miter_stop(sg_miter);
	return;

done:
	data->bytes_xfered += nbytes;
	sg_miter_stop(sg_miter);
	host->sg = NULL;
	smp_wmb();
	set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
}

static void dw_mci_write_data_pio(struct dw_mci *host)
{
	struct sg_mapping_iter *sg_miter = &host->sg_miter;
	void *buf;
	unsigned int offset;
	struct mmc_data	*data = host->data;
	int shift = host->data_shift;
	u32 status;
	unsigned int nbytes = 0, len;
	unsigned int fifo_depth = host->fifo_depth;
	unsigned int remain, fcnt;

	do {
		if (!sg_miter_next(sg_miter))
			goto done;

		host->sg = sg_miter->__sg;
		buf = sg_miter->addr;
		remain = sg_miter->length;
		offset = 0;

		do {
			fcnt = ((fifo_depth -
				 SDMMC_GET_FCNT(mci_readl(host, STATUS)))
					<< shift) - host->part_buf_count;
			len = min(remain, fcnt);
			if (!len)
				break;
			host->push_data(host, (void *)(buf + offset), len);
			offset += len;
			nbytes += len;
			remain -= len;
		} while (remain);
		sg_miter->consumed = offset;

		status = mci_readl(host, MINTSTS);
		mci_writel(host, RINTSTS, SDMMC_INT_TXDR);
		if (status & DW_MCI_DATA_ERROR_FLAGS) {
			host->data_status = status;
			data->bytes_xfered += nbytes;
			sg_miter_stop(sg_miter);
			host->sg = NULL;

			smp_wmb();

			set_bit(EVENT_DATA_ERROR, &host->pending_events);

			tasklet_schedule(&host->tasklet);
			return;
		}
	} while (status & SDMMC_INT_TXDR); /* if TXDR write again */
	data->bytes_xfered += nbytes;

	if (!remain) {
		if (!sg_miter_next(sg_miter))
			goto done;
		sg_miter->consumed = 0;
	}
	sg_miter_stop(sg_miter);
	return;

done:
	data->bytes_xfered += nbytes;
	sg_miter_stop(sg_miter);
	host->sg = NULL;
	smp_wmb();
	set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
}

static void dw_mci_cmd_interrupt(struct dw_mci *host, u32 status)
{
	if (!host->cmd_status)
		host->cmd_status = status;

	smp_wmb();

	set_bit(EVENT_CMD_COMPLETE, &host->pending_events);
	tasklet_schedule(&host->tasklet);
}

/* 
中断注册函的第一个参数中断号就取自于s3c_device_hsmmc3.resource里面的irq参数，sdhci_irq就是中断服务程序，该中断函数一般在插卡、拔卡或者从设备反馈给host信息时会被调用数request

中断服务程序: 
程序首先读取寄存器NORINTSTSn的值，该寄存器中有两个bit分别来表示卡的插入与拔出过程（注意，必须是动态变化过程，才会让相应的两个bit置1）,那么接下来的if语句就是从该寄存器的那两个bit来判断是否有卡的插入或拔出，并同时清除这两个bit，准备下一次的检测，紧接着就调用中断的下半部分函数 sdhci_tasklet_card，其实这个函数也没做什么事情，就是判读如果此时有卡的话就通过mmc_detect_change函数调用 mmc_rescan 函数。
从这个函数的名字都可以猜出个八九不离十，它的功能就是扫描所插入的卡。
											     */


static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
{
	struct dw_mci *host = dev_id;
	u32 status, pending;
	unsigned int pass_count = 0;
	int i;

	do {
		status = mci_readl(host, RINTSTS);
		pending = mci_readl(host, MINTSTS); /* read-only mask reg */

		/*
		 * DTO fix - version 2.10a and below, and only if internal DMA
		 * is configured.
		 */
		if (host->quirks & DW_MCI_QUIRK_IDMAC_DTO) {
			if (!pending &&
			    ((mci_readl(host, STATUS) >> 17) & 0x1fff))
				pending |= SDMMC_INT_DATA_OVER;
		}

		if (!pending)
			break;

		if (pending & DW_MCI_CMD_ERROR_FLAGS) {
			mci_writel(host, RINTSTS, DW_MCI_CMD_ERROR_FLAGS);
			host->cmd_status = status;
			smp_wmb();
			set_bit(EVENT_CMD_COMPLETE, &host->pending_events);
		}

		if (pending & DW_MCI_DATA_ERROR_FLAGS) {
			/* if there is an error report DATA_ERROR */
			mci_writel(host, RINTSTS, DW_MCI_DATA_ERROR_FLAGS);
			host->data_status = status;
			smp_wmb();
			set_bit(EVENT_DATA_ERROR, &host->pending_events);
			if (!(pending & (SDMMC_INT_DTO | SDMMC_INT_DCRC |
					 SDMMC_INT_SBE | SDMMC_INT_EBE)))
				tasklet_schedule(&host->tasklet);
		}

		if (pending & SDMMC_INT_DATA_OVER) {
			mci_writel(host, RINTSTS, SDMMC_INT_DATA_OVER);
			if (!host->data_status)
				host->data_status = status;
			smp_wmb();
			if (host->dir_status == DW_MCI_RECV_STATUS) {
				if (host->sg != NULL)
					dw_mci_read_data_pio(host);
			}
			set_bit(EVENT_DATA_COMPLETE, &host->pending_events);
			tasklet_schedule(&host->tasklet);
		}

		if (pending & SDMMC_INT_RXDR) {
			mci_writel(host, RINTSTS, SDMMC_INT_RXDR);
			if (host->dir_status == DW_MCI_RECV_STATUS && host->sg)
				dw_mci_read_data_pio(host);
		}

		if (pending & SDMMC_INT_TXDR) {
			mci_writel(host, RINTSTS, SDMMC_INT_TXDR);
			if (host->dir_status == DW_MCI_SEND_STATUS && host->sg)
				dw_mci_write_data_pio(host);
		}

		if (pending & SDMMC_INT_CMD_DONE) {
			mci_writel(host, RINTSTS, SDMMC_INT_CMD_DONE);
			dw_mci_cmd_interrupt(host, status);
		}

		if (pending & SDMMC_INT_CD) {
			mci_writel(host, RINTSTS, SDMMC_INT_CD);
			queue_work(host->card_workqueue, &host->card_work);
		}

		/* Handle SDIO Interrupts */
		for (i = 0; i < host->num_slots; i++) {
			struct dw_mci_slot *slot = host->slot[i];
			if (pending & SDMMC_INT_SDIO(i)) {
				mci_writel(host, RINTSTS, SDMMC_INT_SDIO(i));
				mmc_signal_sdio_irq(slot->mmc);
			}
		}

	} while (pass_count++ < 5);

#ifdef CONFIG_MMC_DW_IDMAC
	/* Handle DMA interrupts */
	pending = mci_readl(host, IDSTS);
	if (pending & (SDMMC_IDMAC_INT_TI | SDMMC_IDMAC_INT_RI)) {
		mci_writel(host, IDSTS, SDMMC_IDMAC_INT_TI | SDMMC_IDMAC_INT_RI);
		mci_writel(host, IDSTS, SDMMC_IDMAC_INT_NI);
		host->dma_ops->complete(host);
	}
#endif

	return IRQ_HANDLED;
}

static void dw_mci_work_routine_card(struct work_struct *work)
{
	struct dw_mci *host = container_of(work, struct dw_mci, card_work);
	int i;

	for (i = 0; i < host->num_slots; i++) {
		struct dw_mci_slot *slot = host->slot[i];
		struct mmc_host *mmc = slot->mmc;
		struct mmc_request *mrq;
		int present;
		u32 ctrl;

		present = dw_mci_get_cd(mmc);
		while (present != slot->last_detect_state) {
			dev_dbg(&slot->mmc->class_dev, "card %s\n",
				present ? "inserted" : "removed");

			/* Power up slot (before spin_lock, may sleep) */
			if (present != 0 && host->pdata->setpower)
				host->pdata->setpower(slot->id, mmc->ocr_avail);

			spin_lock_bh(&host->lock);

			/* Card change detected */
			slot->last_detect_state = present;

			/* Mark card as present if applicable */
			if (present != 0)
				set_bit(DW_MMC_CARD_PRESENT, &slot->flags);

			/* Clean up queue if present */
			mrq = slot->mrq;
			if (mrq) {
				if (mrq == host->mrq) {
					host->data = NULL;
					host->cmd = NULL;

					switch (host->state) {
					case STATE_IDLE:
						break;
					case STATE_SENDING_CMD:
						mrq->cmd->error = -ENOMEDIUM;
						if (!mrq->data)
							break;
						/* fall through */
					case STATE_SENDING_DATA:
						mrq->data->error = -ENOMEDIUM;
						dw_mci_stop_dma(host);
						break;
					case STATE_DATA_BUSY:
					case STATE_DATA_ERROR:
						if (mrq->data->error == -EINPROGRESS)
							mrq->data->error = -ENOMEDIUM;
						if (!mrq->stop)
							break;
						/* fall through */
					case STATE_SENDING_STOP:
						mrq->stop->error = -ENOMEDIUM;
						break;
					}

					dw_mci_request_end(host, mrq);
				} else {
					list_del(&slot->queue_node);
					mrq->cmd->error = -ENOMEDIUM;
					if (mrq->data)
						mrq->data->error = -ENOMEDIUM;
					if (mrq->stop)
						mrq->stop->error = -ENOMEDIUM;

					spin_unlock(&host->lock);
					mmc_request_done(slot->mmc, mrq);
					spin_lock(&host->lock);
				}
			}

			/* Power down slot */
			if (present == 0) {
				clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);

				/*
				 * Clear down the FIFO - doing so generates a
				 * block interrupt, hence setting the
				 * scatter-gather pointer to NULL.
				 */
				sg_miter_stop(&host->sg_miter);
				host->sg = NULL;

				ctrl = mci_readl(host, CTRL);
				ctrl |= SDMMC_CTRL_FIFO_RESET;
				mci_writel(host, CTRL, ctrl);

#ifdef CONFIG_MMC_DW_IDMAC
				ctrl = mci_readl(host, BMOD);
				/* Software reset of DMA */
				ctrl |= SDMMC_IDMAC_SWRESET;
				mci_writel(host, BMOD, ctrl);
#endif

			}

			spin_unlock_bh(&host->lock);

			/* Power down slot (after spin_unlock, may sleep) */
			if (present == 0 && host->pdata->setpower)
				host->pdata->setpower(slot->id, 0);

			present = dw_mci_get_cd(mmc);
		}

		mmc_detect_change(slot->mmc, msecs_to_jiffies(host->pdata->detect_delay_ms));
	}
}

static int __init dw_mci_init_slot(struct dw_mci *host, unsigned int id)
{
	struct mmc_host *mmc;
	struct dw_mci_slot *slot;

	mmc = mmc_alloc_host(sizeof(struct dw_mci_slot), &host->dev);
	if (!mmc)
		return -ENOMEM;

	slot = mmc_priv(mmc);
	slot->id = id;
	slot->mmc = mmc;
	slot->host = host;

	mmc->ops = &dw_mci_ops;					//Ops
	mmc->f_min = DIV_ROUND_UP(host->bus_hz, 510);
	mmc->f_max = host->bus_hz;

	if (host->pdata->get_ocr)
		mmc->ocr_avail = host->pdata->get_ocr(id);
	else
		mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;

	/*
	 * Start with slot power disabled, it will be enabled when a card
	 * is detected.
	 */
	if (host->pdata->setpower)
		host->pdata->setpower(id, 0);

	if (host->pdata->caps)
		mmc->caps = host->pdata->caps;

	if (host->pdata->caps2)
		mmc->caps2 = host->pdata->caps2;

	if (host->pdata->get_bus_wd)
		if (host->pdata->get_bus_wd(slot->id) >= 4)
			mmc->caps |= MMC_CAP_4_BIT_DATA;

	if (host->pdata->quirks & DW_MCI_QUIRK_HIGHSPEED)
		mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;

	if (mmc->caps2 & MMC_CAP2_POWEROFF_NOTIFY)
		mmc->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
	else
		mmc->power_notify_type = MMC_HOST_PW_NOTIFY_NONE;

	if (host->pdata->blk_settings) {
		mmc->max_segs = host->pdata->blk_settings->max_segs;
		mmc->max_blk_size = host->pdata->blk_settings->max_blk_size;
		mmc->max_blk_count = host->pdata->blk_settings->max_blk_count;
		mmc->max_req_size = host->pdata->blk_settings->max_req_size;
		mmc->max_seg_size = host->pdata->blk_settings->max_seg_size;
	} else {
		/* Useful defaults if platform data is unset. */
#ifdef CONFIG_MMC_DW_IDMAC
		mmc->max_segs = host->ring_size;
		mmc->max_blk_size = 65536;
		mmc->max_blk_count = host->ring_size;
		mmc->max_seg_size = 0x1000;
		mmc->max_req_size = mmc->max_seg_size * mmc->max_blk_count;
#else
		mmc->max_segs = 64;
		mmc->max_blk_size = 65536; /* BLKSIZ is 16 bits */
		mmc->max_blk_count = 512;
		mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
		mmc->max_seg_size = mmc->max_req_size;
#endif /* CONFIG_MMC_DW_IDMAC */
	}

	host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
	if (IS_ERR(host->vmmc)) {
		pr_info("%s: no vmmc regulator found\n", mmc_hostname(mmc));
		host->vmmc = NULL;
	} else
		regulator_enable(host->vmmc);

	if (dw_mci_get_cd(mmc))
		set_bit(DW_MMC_CARD_PRESENT, &slot->flags);
	else
		clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);

	host->slot[id] = slot;
	mmc_add_host(mmc);	/* 我们先看一下mmc_add_host这个函数，它的功能就是通过device_add函数,将设备注册进linux设备模型，最终的结果就
				   是在sys/bus/platform/devices目录下能见到s3c-sdhci.1,s3c-sdhci.2,s3c-sdhci.3设备节点。*/

#if defined(CONFIG_DEBUG_FS)
	dw_mci_init_debugfs(slot);
#endif

	/* Card initially undetected */
	slot->last_detect_state = 0;

	/*
	 * Card may have been plugged in prior to boot so we
	 * need to run the detect tasklet
	 */
	queue_work(host->card_workqueue, &host->card_work);

	return 0;
}

static void dw_mci_cleanup_slot(struct dw_mci_slot *slot, unsigned int id)
{
	/* Shutdown detect IRQ */
	if (slot->host->pdata->exit)
		slot->host->pdata->exit(id);

	/* Debugfs stuff is cleaned up by mmc core */
	mmc_remove_host(slot->mmc);
	slot->host->slot[id] = NULL;
	mmc_free_host(slot->mmc);
}

static void dw_mci_init_dma(struct dw_mci *host)
{
	/* Alloc memory for sg translation */
	host->sg_cpu = dma_alloc_coherent(&host->dev, PAGE_SIZE,
					  &host->sg_dma, GFP_KERNEL);
	if (!host->sg_cpu) {
		dev_err(&host->dev, "%s: could not alloc DMA memory\n",
			__func__);
		goto no_dma;
	}

	/* Determine which DMA interface to use */
#ifdef CONFIG_MMC_DW_IDMAC
	host->dma_ops = &dw_mci_idmac_ops;
	dev_info(&host->dev, "Using internal DMA controller.\n");		//1
#endif

	if (!host->dma_ops)
		goto no_dma;

	if (host->dma_ops->init && host->dma_ops->start &&
	    host->dma_ops->stop && host->dma_ops->cleanup) {
		if (host->dma_ops->init(host)) {
			dev_err(&host->dev, "%s: Unable to initialize "
				"DMA Controller.\n", __func__);
			goto no_dma;
		}
	} else {
		dev_err(&host->dev, "DMA initialization not found.\n");
		goto no_dma;
	}

	host->use_dma = 1;
	return;

no_dma:
	dev_info(&host->dev, "Using PIO mode.\n");
	host->use_dma = 0;
	return;
}

static bool mci_wait_reset(struct device *dev, struct dw_mci *host)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(500);
	unsigned int ctrl;

	mci_writel(host, CTRL, (SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET |
				SDMMC_CTRL_DMA_RESET));

	/* wait till resets clear */
	do {
		ctrl = mci_readl(host, CTRL);
		if (!(ctrl & (SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET |
			      SDMMC_CTRL_DMA_RESET)))
			return true;
	} while (time_before(jiffies, timeout));

	dev_err(dev, "Timeout resetting block (ctrl %#x)\n", ctrl);

	return false;
}

int dw_mci_probe(struct dw_mci *host)
{
	int width, i = 0, ret = 0;
	u32 fifo_size;
	struct dw_mci_board *brd = NULL;

	if (!host->pdata || !host->pdata->init) {
		dev_err(&host->dev,
			"Platform data must supply init function\n");
		return -ENODEV;
	}

	if (!host->pdata->select_slot && host->pdata->num_slots > 1) {
		dev_err(&host->dev,
			"Platform data must supply select_slot function\n");
		return -ENODEV;
	}

	if (!host->pdata->bus_hz) {
		dev_err(&host->dev,
			"Platform data must supply bus speed\n");
		return -ENODEV;
	}

	host->hclk = clk_get(&host->dev, host->pdata->hclk_name);
	if (IS_ERR(host->hclk)) {
		dev_err(&host->dev,
				"failed to get hclk\n");
		ret = PTR_ERR(host->hclk);
		goto err_freehost;
	}
	clk_enable(host->hclk);

	host->cclk = clk_get(&host->dev, host->pdata->cclk_name);
	if (IS_ERR(host->cclk)) {
		dev_err(&host->dev,
				"failed to get cclk\n");
		ret = PTR_ERR(host->cclk);
		goto err_free_hclk;
	}
	clk_enable(host->cclk);

	if (host->pdata->cfg_gpio)
		host->pdata->cfg_gpio(MMC_BUS_WIDTH_8);

	host->pdata->bus_hz = 66 * 1000 * 1000;

	host->bus_hz = host->pdata->bus_hz;
	host->quirks = host->pdata->quirks;

	/* Set Phase Shift Register */
	if (soc_is_exynos4212() || soc_is_exynos4412()) {
		brd = host->pdata;
		brd->sdr_timing = 0x00010001;
		brd->ddr_timing = 0x00010001;
	}

	spin_lock_init(&host->lock);
	INIT_LIST_HEAD(&host->queue);

	/*
	 * Get the host data width - this assumes that HCON has been set with
	 * the correct values.
	 */
	i = (mci_readl(host, HCON) >> 7) & 0x7;
	if (!i) {
		host->push_data = dw_mci_push_data16;
		host->pull_data = dw_mci_pull_data16;
		width = 16;
		host->data_shift = 1;
	} else if (i == 2) {
		host->push_data = dw_mci_push_data64;
		host->pull_data = dw_mci_pull_data64;
		width = 64;
		host->data_shift = 3;
	} else {
		/* Check for a reserved value, and warn if it is */
		WARN((i != 1),
		     "HCON reports a reserved host data width!\n"
		     "Defaulting to 32-bit access.\n");
		host->push_data = dw_mci_push_data32;
		host->pull_data = dw_mci_pull_data32;
		width = 32;
		host->data_shift = 2;
	}

	/* Reset all blocks */
	if (!mci_wait_reset(&host->dev, host))
		return -ENODEV;

	host->dma_ops = host->pdata->dma_ops;
	dw_mci_init_dma(host);

	/* Clear the interrupts for the host controller */
	mci_writel(host, RINTSTS, 0xFFFFFFFF);
	mci_writel(host, INTMASK, 0); /* disable all mmc interrupt first */

	/* Put in max timeout */
	mci_writel(host, TMOUT, 0xFFFFFFFF);

	/*
	 * FIFO threshold settings  RxMark  = fifo_size / 2 - 1,
	 *                          Tx Mark = fifo_size / 2 DMA Size = 8
	 */
	if (!host->pdata->fifo_depth) {
		/*
		 * Power-on value of RX_WMark is FIFO_DEPTH-1, but this may
		 * have been overwritten by the bootloader, just like we're
		 * about to do, so if you know the value for your hardware, you
		 * should put it in the platform data.
		 */
		fifo_size = mci_readl(host, FIFOTH);
		fifo_size = 1 + ((fifo_size >> 16) & 0xfff);
	} else {
		fifo_size = host->pdata->fifo_depth;
	}
	host->fifo_depth = fifo_size;
	host->fifoth_val = ((0x2 << 28) | ((fifo_size/2 - 1) << 16) |
			((fifo_size/2) << 0));
	mci_writel(host, FIFOTH, host->fifoth_val);

	/* disable clock to CIU */
	mci_writel(host, CLKENA, 0);
	mci_writel(host, CLKSRC, 0);

	tasklet_init(&host->tasklet, dw_mci_tasklet_func, (unsigned long)host);
	host->card_workqueue = alloc_workqueue("dw-mci-card",
			WQ_MEM_RECLAIM | WQ_NON_REENTRANT, 1);
	if (!host->card_workqueue)
		goto err_dmaunmap;
	INIT_WORK(&host->card_work, dw_mci_work_routine_card);
	ret = request_irq(host->irq, dw_mci_interrupt, host->irq_flags, "dw-mci", host);     /* 中断注册函的第一个参数中断号就取自于s3c_device_hsmmc3.resource里面的irq参数，
												sdhci_irq就是中断服务程序，该中断函数一般在插卡、拔卡或者从设备反馈给host信息时会被调用数request


sdhci 中断服务程序: 
程序首先读取寄存器NORINTSTSn的值，该寄存器中有两个bit分别来表示卡的插入与拔出过程（注意，必须是动态变化过程，才会让相应的两个bit置1）,那么接下来的if语句就是从该寄存器的那两个bit来判断是否有卡的插入或拔出，并同时清除这两个bit，准备下一次的检测，紧接着就调用中断的下半部分函数 sdhci_tasklet_card，其实这个函数也没做什么事情，就是判读如果此时有卡的话就通过mmc_detect_change函数调用 mmc_rescan 函数。
从这个函数的名字都可以猜出个99%，它的功能就是扫描所插入的卡。


mmc_rescan函数:  //当然core.c定義  動作：MMC != SDIO
这个函数我们重点关注上述两个地方，其实真正的扫描动作发生在函数mmc_rescan_try_freq函数里面，该函数的第二个参数表示以什么样的频率去进行扫描，那么可选的频率值在那个数组freqs里面，一般当用某个频率值扫描成功后，
就直接退出了，否则，会以下一个更低的频率值来扫描，我所使用的WIFI模块就是以400KHz的频率扫描成功的。


mmc_rescan_try_freq函数： //core/core.c
该函数首先发送复位命令（不过该命令只有SDIO类型的卡才能够识别），然后发送CMD0，让设备进入IDLE模式，紧接着发送CMD8，获取该卡所支持的电压值，最后就是重点了，从所调用的各个函数名字可以看出，它是在试探该卡是否为SDIO? SD? MMC?


 	// Order's important: probe SDIO, then SD, then MMC
	if (!mmc_attach_sdio(host))
		return 0;
	if (!mmc_attach_sd(host))
		return 0;
	if (!mmc_attach_mmc(host))
		return 0;

	mmc_power_off(host);



改天継続：　一番下へ
那么接下来的文就是要分析上面的三个函数(mmc_attach_xx)，看它是如何识别SDIO、SD、MMC的。

*/
	if (ret)
		goto err_workqueue;

	if (host->pdata->num_slots)
		host->num_slots = host->pdata->num_slots;
	else
		host->num_slots = ((mci_readl(host, HCON) >> 1) & 0x1F) + 1;

	/*
	 * Enable interrupts for command done, data over, data empty, card det,
	 * receive ready and error such as transmit, receive timeout, crc error
	 */
	mci_writel(host, RINTSTS, 0xFFFFFFFF);
	mci_writel(host, INTMASK, SDMMC_INT_CMD_DONE | SDMMC_INT_DATA_OVER |
		   SDMMC_INT_TXDR | SDMMC_INT_RXDR |
		   DW_MCI_ERROR_FLAGS | SDMMC_INT_CD);
	mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE); /* Enable mci interrupt */

	/* We need at least one slot to succeed */
	for (i = 0; i < host->num_slots; i++) {
		ret = dw_mci_init_slot(host, i);
		if (ret) {
			ret = -ENODEV;
			goto err_init_slot;
		}
	}

	/*
	 * In 2.40a spec, Data offset is changed.
	 * Need to check the version-id and set data-offset for DATA register.
	 */
	host->verid = SDMMC_GET_VERID(mci_readl(host, VERID));
	dev_info(&host->dev, "Version ID is %04x\n", host->verid);			//2

	if (host->verid < DW_MMC_240A)
		host->data_offset = DATA_OFFSET;
	else
		host->data_offset = DATA_240A_OFFSET;

	dev_info(&host->dev, "DW MMC controller at irq %d, "
		 "%d bit host data width, "
		 "%u deep fifo\n",
		 host->irq, width, fifo_size);						//3
	if (host->quirks & DW_MCI_QUIRK_IDMAC_DTO)
		dev_info(&host->dev, "Internal DMAC interrupt fix enabled.\n");

	return 0;

err_init_slot:
	/* De-init any initialized slots */
	while (i > 0) {
		if (host->slot[i])
			dw_mci_cleanup_slot(host->slot[i], i);
		i--;
	}
	free_irq(host->irq, host);

err_workqueue:
	destroy_workqueue(host->card_workqueue);

err_dmaunmap:
	if (host->use_dma && host->dma_ops->exit)
		host->dma_ops->exit(host);
	dma_free_coherent(&host->dev, PAGE_SIZE,
			  host->sg_cpu, host->sg_dma);

	if (host->vmmc) {
		regulator_disable(host->vmmc);
		regulator_put(host->vmmc);
	}
	clk_disable(host->cclk);
	clk_put(host->cclk);
err_free_hclk:
	clk_disable(host->hclk);
	clk_put(host->hclk);
err_freehost:
	return ret;
}
EXPORT_SYMBOL(dw_mci_probe);

void dw_mci_remove(struct dw_mci *host)
{
	int i;

	mci_writel(host, RINTSTS, 0xFFFFFFFF);
	mci_writel(host, INTMASK, 0); /* disable all mmc interrupt first */

	for (i = 0; i < host->num_slots; i++) {
		dev_dbg(&host->dev, "remove slot %d\n", i);
		if (host->slot[i])
			dw_mci_cleanup_slot(host->slot[i], i);
	}

	/* disable clock to CIU */
	mci_writel(host, CLKENA, 0);
	mci_writel(host, CLKSRC, 0);

	free_irq(host->irq, host);
	destroy_workqueue(host->card_workqueue);
	dma_free_coherent(&host->dev, PAGE_SIZE, host->sg_cpu, host->sg_dma);

	if (host->use_dma && host->dma_ops->exit)
		host->dma_ops->exit(host);

	if (host->vmmc) {
		regulator_disable(host->vmmc);
		regulator_put(host->vmmc);
	}

	clk_disable(host->cclk);
	clk_put(host->cclk);
	clk_disable(host->hclk);
	clk_put(host->hclk);
}
EXPORT_SYMBOL(dw_mci_remove);



#ifdef CONFIG_PM_SLEEP
/*
 * TODO: we should probably disable the clock to the card in the suspend path.
 */
int dw_mci_suspend(struct dw_mci *host)
{
	int i, ret = 0;

	for (i = 0; i < host->num_slots; i++) {
		struct dw_mci_slot *slot = host->slot[i];
		if (!slot)
			continue;
		ret = mmc_suspend_host(slot->mmc);
		if (ret < 0) {
			while (--i >= 0) {
				slot = host->slot[i];
				if (slot)
					mmc_resume_host(host->slot[i]->mmc);
			}
			return ret;
		}
	}

	if (host->vmmc)
		regulator_disable(host->vmmc);

	return 0;
}
EXPORT_SYMBOL(dw_mci_suspend);

int dw_mci_resume(struct dw_mci *host)
{
	int i, ret;

	if (host->vmmc)
		regulator_enable(host->vmmc);

	if (!mci_wait_reset(&host->dev, host)) {
		ret = -ENODEV;
		return ret;
	}

	if (host->dma_ops->init)
		host->dma_ops->init(host);

	/* Restore the old value at FIFOTH register */
	mci_writel(host, FIFOTH, host->fifoth_val);

	mci_writel(host, RINTSTS, 0xFFFFFFFF);
	mci_writel(host, INTMASK, SDMMC_INT_CMD_DONE | SDMMC_INT_DATA_OVER |
		   SDMMC_INT_TXDR | SDMMC_INT_RXDR |
		   DW_MCI_ERROR_FLAGS | SDMMC_INT_CD);
	mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);

	for (i = 0; i < host->num_slots; i++) {
		struct dw_mci_slot *slot = host->slot[i];
		if (!slot)
			continue;
		ret = mmc_resume_host(host->slot[i]->mmc);
		if (ret < 0)
			return ret;
	}
	return 0;
}
EXPORT_SYMBOL(dw_mci_resume);
#endif /* CONFIG_PM_SLEEP */

static int __init dw_mci_init(void)
{
	printk(KERN_INFO "Synopsys Designware Multimedia Card Interface Driver");
	return 0;
}

static void __exit dw_mci_exit(void)
{
}

module_init(dw_mci_init);
module_exit(dw_mci_exit);

MODULE_DESCRIPTION("DW Multimedia Card Interface driver");
MODULE_AUTHOR("NXP Semiconductor VietNam");
MODULE_AUTHOR("Imagination Technologies Ltd");
MODULE_LICENSE("GPL v2");


/* 
SD卡的命令格式及解析

1.SD卡命令组成

SD卡的指令由6字节(Byte)组成，如下：
　　Byte1：0 1 x x x x x x(命令号，由指令标志定义，如CMD39为100111即16进制0x27，那么完整的CMD39第一字节为01100111，即0x27+0x40)
　　Byte2-5:Command Arguments,命令参数，有些命令没有参数
　　Byte6:前7位为CRC(Cyclic Redundacy Check，循环冗余校验)校验位，最后一位为停止位0

2.SD卡的命令
SD卡命令共分为12类，分别为class0到class11，不同的SD卡，主控根据其功能，支持不同的命令集，如下:

　　Class0 :(卡的识别、初始化等基本命令集)
	　　　　CMD0:复位SD 卡.
	　　　　CMD1:读OCR寄存器.
	　　　　CMD9:读CSD寄存器.
	　　　　CMD10:读CID寄存器.
	　　　　CMD12:停止读多块时的数据传输
	　　　　CMD13:读 Card_Status 寄存器

　　Class2 (读卡命令集):
	　　　　CMD16:设置块的长度
	　　　　CMD17:读单块
	　　　　CMD18:读多块,直至主机发送CMD12为止

　　Class4(写卡命令集) :
	　　　　CMD24:写单块.
	　　　　CMD25:写多块.
	　　　　CMD27:写CSD寄存器 .

　　Class5 (擦除卡命令集):
	　　　　CMD32:设置擦除块的起始地址.
	　　　　CMD33:设置擦除块的终止地址.
	　　　　CMD38: 擦除所选择的块.

　　Class6(写保护命令集):
	　　　　CMD28:设置写保护块的地址.
	　　　　CMD29:擦除写保护块的地址.
	　　　　CMD30: Ask the card for the status of the write protection bits

　　class7：卡的锁定，解锁功能命令集
　　class8：申请特定命令集 。
　　class10 －11 ：保留
*/


/*

継続：

那么接下来的文就是要分析上面的三个函数(mmc_attach_xx)，看它是如何识别SDIO、SD、MMC的。

SDIO的识别和操作：　WIFI　Card

	从上面文的最后，我们知道host在扫描卡的过程中，其识别的顺序为SDIO  SD MMC，并且从它的注释可以看出，这个顺序是很重要的。
	那这文我们就看看SDIO的识别过程，它对应的函数就是mmc_attach_sdio(host) 　//函数位于drivers/mmc/core/sdio.c

　　这个函数大概来说做了如下的工作:
	　　　　1、向卡发送CMD5命令，该命令有两个作用：
	　　　　　　第一，通过判断卡是否有反馈信息来判断是否为SDIO设备（只有SDIO设备才对CMD5命令有反馈，其他卡是没有回馈的）
	　　　　　　第二，如果是SDIO设备，就会给host反馈电压信息，就是说告诉host，本卡所能支持的电压是多少多少。
	　　　　2、host根据SDIO卡反馈回来的电压要求，给其提供合适的电压。
	　　　　3、初始化该SDIO卡
	　　　　4、注册SDIO的各个功能模块
	　　　　5、注册SDIO卡

　　对于以上功能的具体解释，下面将结合程序,娓娓道来:
	1.CMD5の発送：
		err = mmc_send_io_op_cond(host, 0, &ocr);  //发送的CMD5命令，如果卡对该命令有回馈的话，err就是0，否则，err为非0，直接退出了.
		if (err)				   //并且需要重点说明的一点就是，该函数的最后一个参数ocr,它是存储反馈命令的，SDIO设备对CMD5的反馈命令为R4，
			return err;			   //下面来仔细分析一下这个R4，因为后面要用到这个R4命令。从SDIO spec文档里面，我们能得到R4命令的格式
				//该命令有48位，但我们的ocr变量是32位的，那怎么存储？ 去掉原命令的开头8位以及结尾的8位，只保留中间的32为，也就是截短后的命令格式.


	2.配置电压:
		if (ocr & 0x7F) {
			printk(KERN_WARNING "%s: card claims to support voltages "
			"below the defined range. These will be ignored.\n");

			mmc_hostname(host);
			ocr &= ~0x7F;							
		}
		
		host->ocr = mmc_select_volatage(host, ocr);

		ocr就是我们上面讲的反馈命令R4（截短之后的32位），那么 ocr & 0x7f的意义是什么？ 从R4的格式就可以看出来，其低24位就代表了所能支持的电压范围，
		再看一下这24位的OCR格式...ocr&0x7f的意义: 就是弃那些保留的电压范围.

		
]
		重点关注mmc_select_voltage:
		...
		ocr &= host->ocr_avail;	//相与过程,就是判断host实际所支持的电压与card所需要的电压是否匹配，如果匹配，那么ocr的值就非0，否则就为0.
		bit = ffs(ocr);      //ffs()的作用就是返回参数中第一个为1的bit的位置（ffs(0)=0,ffs(1)=1,ffs(8)=4）,那么在这里的作用就是取出card需要的实际电压是多少；
		....
		mmc_set_ios(host);   //里面通过调用sdhci_set_power将host->ios.vdd所代表的电压写入寄存器PWRCONn中完成那个对电压的重新配置...

	3.初始化SDIO卡
		err = mmc_sdio_init_card(host, host->ocr, NULL, 0); //就是初始化SDIO卡的函数  这个函数很长，也很重要，这里我就不列出其程序代码了，只是列出其中最重要的几条：
		if (err)
			goto err;
		card = host->card;

			　　　　1、通过函数mmc_alloc_card分配一个mmc_card的变量card
			　　　　2、通过读取R4命令中的bit27(也就是Memory Present)来判断此卡是纯IO卡,还是同时包含存储功能。
					我使用的WIFI模块为纯IO功能,所以card->type = MMC_TYPE_SDIO(这个很重要,以后会用到)
			       接下来重点分析MMC_TYPE_SDIO的情况:
			　　　　3、通过发送CMD3命令获取设备的从地址（relative addr）,并且存放在变量card->rca中。我使用的WIFI模块的card->rca = 1
			　　　　4、通过发送CMD7，选中相应从地址的卡
			　　　　5、通过调用函数mmc_set_clock设置卡工作的时钟频率
			　　　　6、通过发送CMD52命令，设置4位数据传输模式

 
	4.注册SDIO功能模块  /core/sdio.c 
			// The number of functions on the card is encoded inside the ocr.
			funcs = (ocr & 0x70000000) >> 28;	//变量funcs存储该SDIO卡所包含的IO功能块的个数
			card->sdio_funcs = 0;

			for (i = 0; i < funcs; i++, card->sdio_funcs++) { //逐一初始化各个IO功能块
					...
					tmp = sdio_alloc_func(host->card);
							
				
			重点看一下该sdio_init_func()的内容: ...
					...分配sdio_func结构体变量，该结构体存储了功能块的参数。
　　					...给功能块编号，编号是从1到7（因为一个SDIO设备最多只有7个功能块），存储在变量func->num中
　　					...读取SDIO卡中的FBR寄存器中关于该卡的功能类型的数据，存储在func->class变量中（具体关于FBR寄存器内容可参SDIO spec文档）
　　					...读取SDIO卡中的CIS寄存器的内容

				for (i = 0;i < funcs;i++) {
					err = sdio_add_func(host->card->sdio_func[i]);
					if (err)
						goto remove_added;
				}
　　				上面的程序就是将功能模块逐个的注册进设备模型，这里想重点说明一下注册的名称（name），它是由三部分组成的，每部分之间用冒号隔开，（即 host的名称：rca：功能块编号)。
　　				具体到我使用的WIFI模块，因为其host名称是mmc2,rca = 1,并且有两个功能模块(功能模块编号分别是1和2)，所以在/sys/bus/sdio/devices目录下能见到如下两个设备名
					　　　　mmc2:0001:1
					　　　　mmc2:0001:2
				
	5.注册SDIO卡
			mmc_add_card()函数就是注册card了（这个card是在第3部分，初始化SDIO卡 里面分配和定义的）
				...给card命名，格式为host名字：从地址,对于我的WIFI模块 就是mmc2:0001
				...根据card->type来分辨出card的类型，给赋予相应的字符串，我的WIFI模块就是"SDIO"	
				...打印信息，我的打印信息为  mmc2:new high speed SDIO card at address 0001(通常看内核启动信息中是否有该语句来判断card是否被正确识别)
				...将card注册进linux设备模型  注册结果就是可以在/sys/bus/mmc/devices目录下见到card的名字，我的就是mmc2:0001				
*/