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[linux-rt-nao.git] / drivers / mmc / host / atmel-mci.c

/*
 * Atmel MultiMedia Card Interface driver
 *
 * Copyright (C) 2004-2008 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/blkdev.h>
#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/scatterlist.h>
#include <linux/seq_file.h>
#include <linux/stat.h>

#include <linux/mmc/host.h>
#include <linux/atmel-mci.h>

#include <asm/io.h>
#include <asm/unaligned.h>

#include <mach/board.h>

#include "atmel-mci-regs.h"

#define ATMCI_DATA_ERROR_FLAGS  (MCI_DCRCE | MCI_DTOE | MCI_OVRE | MCI_UNRE)
#define ATMCI_DMA_THRESHOLD     16

enum {
        EVENT_CMD_COMPLETE = 0,
        EVENT_XFER_COMPLETE,
        EVENT_DATA_COMPLETE,
        EVENT_DATA_ERROR,
};

enum atmel_mci_state {
        STATE_IDLE = 0,
        STATE_SENDING_CMD,
        STATE_SENDING_DATA,
        STATE_DATA_BUSY,
        STATE_SENDING_STOP,
        STATE_DATA_ERROR,
};

struct atmel_mci_dma {
#ifdef CONFIG_MMC_ATMELMCI_DMA
        struct dma_chan                 *chan;
        struct dma_async_tx_descriptor  *data_desc;
#endif
};

/**
 * struct atmel_mci - MMC controller state shared between all slots
 * @lock: Spinlock protecting the queue and associated data.
 * @regs: Pointer to MMIO registers.
 * @sg: Scatterlist entry currently being processed by PIO code, if any.
 * @pio_offset: Offset into the current scatterlist entry.
 * @cur_slot: The slot which is currently using the controller.
 * @mrq: The request currently being processed on @cur_slot,
 *      or NULL if the controller is idle.
 * @cmd: The command currently being sent to the card, or NULL.
 * @data: The data currently being transferred, or NULL if no data
 *      transfer is in progress.
 * @dma: DMA client state.
 * @data_chan: DMA channel being used for the current data transfer.
 * @cmd_status: Snapshot of SR taken upon completion of the current
 *      command. Only valid when EVENT_CMD_COMPLETE is pending.
 * @data_status: Snapshot of SR taken upon completion of the current
 *      data transfer. Only valid when EVENT_DATA_COMPLETE or
 *      EVENT_DATA_ERROR is pending.
 * @stop_cmdr: Value to be loaded into CMDR when the stop command is
 *      to be sent.
 * @tasklet: Tasklet running the request state machine.
 * @pending_events: Bitmask of events flagged by the interrupt handler
 *      to be processed by the tasklet.
 * @completed_events: Bitmask of events which the state machine has
 *      processed.
 * @state: Tasklet state.
 * @queue: List of slots waiting for access to the controller.
 * @need_clock_update: Update the clock rate before the next request.
 * @need_reset: Reset controller before next request.
 * @mode_reg: Value of the MR register.
 * @bus_hz: The rate of @mck in Hz. This forms the basis for MMC bus
 *      rate and timeout calculations.
 * @mapbase: Physical address of the MMIO registers.
 * @mck: The peripheral bus clock hooked up to the MMC controller.
 * @pdev: Platform device associated with the MMC controller.
 * @slot: Slots sharing this MMC controller.
 *
 * Locking
 * =======
 *
 * @lock is a softirq-safe spinlock protecting @queue as well as
 * @cur_slot, @mrq and @state. These must always be updated
 * at the same time while holding @lock.
 *
 * @lock also protects mode_reg and need_clock_update since these are
 * used to synchronize mode register updates with the queue
 * processing.
 *
 * The @mrq field of struct atmel_mci_slot is also protected by @lock,
 * and must always be written at the same time as the slot is added to
 * @queue.
 *
 * @pending_events and @completed_events are accessed using atomic bit
 * operations, so they don't need any locking.
 *
 * None of the fields touched by the interrupt handler need any
 * locking. However, ordering is important: Before EVENT_DATA_ERROR or
 * EVENT_DATA_COMPLETE is set in @pending_events, all data-related
 * interrupts must be disabled and @data_status updated with a
 * snapshot of SR. Similarly, before EVENT_CMD_COMPLETE is set, the
 * CMDRDY interupt must be disabled and @cmd_status updated with a
 * snapshot of SR, and before EVENT_XFER_COMPLETE can be set, the
 * bytes_xfered field of @data must be written. This is ensured by
 * using barriers.
 */
struct atmel_mci {
        spinlock_t              lock;
        void __iomem            *regs;

        struct scatterlist      *sg;
        unsigned int            pio_offset;

        struct atmel_mci_slot   *cur_slot;
        struct mmc_request      *mrq;
        struct mmc_command      *cmd;
        struct mmc_data         *data;

        struct atmel_mci_dma    dma;
        struct dma_chan         *data_chan;

        u32                     cmd_status;
        u32                     data_status;
        u32                     stop_cmdr;

        struct tasklet_struct   tasklet;
        unsigned long           pending_events;
        unsigned long           completed_events;
        enum atmel_mci_state    state;
        struct list_head        queue;

        bool                    need_clock_update;
        bool                    need_reset;
        u32                     mode_reg;
        unsigned long           bus_hz;
        unsigned long           mapbase;
        struct clk              *mck;
        struct platform_device  *pdev;

        struct atmel_mci_slot   *slot[ATMEL_MCI_MAX_NR_SLOTS];
};

/**
 * struct atmel_mci_slot - MMC slot state
 * @mmc: The mmc_host representing this slot.
 * @host: The MMC controller this slot is using.
 * @sdc_reg: Value of SDCR to be written before using 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 atmel_mci.
 * @clock: Clock rate configured by set_ios(). Protected by host->lock.
 * @flags: Random state bits associated with the slot.
 * @detect_pin: GPIO pin used for card detection, or negative if not
 *      available.
 * @wp_pin: GPIO pin used for card write protect sending, or negative
 *      if not available.
 * @detect_timer: Timer used for debouncing @detect_pin interrupts.
 */
struct atmel_mci_slot {
        struct mmc_host         *mmc;
        struct atmel_mci        *host;

        u32                     sdc_reg;

        struct mmc_request      *mrq;
        struct list_head        queue_node;

        unsigned int            clock;
        unsigned long           flags;
#define ATMCI_CARD_PRESENT      0
#define ATMCI_CARD_NEED_INIT    1
#define ATMCI_SHUTDOWN          2

        int                     detect_pin;
        int                     wp_pin;

        struct timer_list       detect_timer;
};

#define atmci_test_and_clear_pending(host, event)               \
        test_and_clear_bit(event, &host->pending_events)
#define atmci_set_completed(host, event)                        \
        set_bit(event, &host->completed_events)
#define atmci_set_pending(host, event)                          \
        set_bit(event, &host->pending_events)

/*
 * The debugfs stuff below is mostly optimized away when
 * CONFIG_DEBUG_FS is not set.
 */
static int atmci_req_show(struct seq_file *s, void *v)
{
        struct atmel_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 atmci_req_open(struct inode *inode, struct file *file)
{
        return single_open(file, atmci_req_show, inode->i_private);
}

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

static void atmci_show_status_reg(struct seq_file *s,
                const char *regname, u32 value)
{
        static const char       *sr_bit[] = {
                [0]     = "CMDRDY",
                [1]     = "RXRDY",
                [2]     = "TXRDY",
                [3]     = "BLKE",
                [4]     = "DTIP",
                [5]     = "NOTBUSY",
                [8]     = "SDIOIRQA",
                [9]     = "SDIOIRQB",
                [16]    = "RINDE",
                [17]    = "RDIRE",
                [18]    = "RCRCE",
                [19]    = "RENDE",
                [20]    = "RTOE",
                [21]    = "DCRCE",
                [22]    = "DTOE",
                [30]    = "OVRE",
                [31]    = "UNRE",
        };
        unsigned int            i;

        seq_printf(s, "%s:\t0x%08x", regname, value);
        for (i = 0; i < ARRAY_SIZE(sr_bit); i++) {
                if (value & (1 << i)) {
                        if (sr_bit[i])
                                seq_printf(s, " %s", sr_bit[i]);
                        else
                                seq_puts(s, " UNKNOWN");
                }
        }
        seq_putc(s, '\n');
}

static int atmci_regs_show(struct seq_file *s, void *v)
{
        struct atmel_mci        *host = s->private;
        u32                     *buf;

        buf = kmalloc(MCI_REGS_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /*
         * Grab a more or less consistent snapshot. Note that we're
         * not disabling interrupts, so IMR and SR may not be
         * consistent.
         */
        spin_lock_bh(&host->lock);
        clk_enable(host->mck);
        memcpy_fromio(buf, host->regs, MCI_REGS_SIZE);
        clk_disable(host->mck);
        spin_unlock_bh(&host->lock);

        seq_printf(s, "MR:\t0x%08x%s%s CLKDIV=%u\n",
                        buf[MCI_MR / 4],
                        buf[MCI_MR / 4] & MCI_MR_RDPROOF ? " RDPROOF" : "",
                        buf[MCI_MR / 4] & MCI_MR_WRPROOF ? " WRPROOF" : "",
                        buf[MCI_MR / 4] & 0xff);
        seq_printf(s, "DTOR:\t0x%08x\n", buf[MCI_DTOR / 4]);
        seq_printf(s, "SDCR:\t0x%08x\n", buf[MCI_SDCR / 4]);
        seq_printf(s, "ARGR:\t0x%08x\n", buf[MCI_ARGR / 4]);
        seq_printf(s, "BLKR:\t0x%08x BCNT=%u BLKLEN=%u\n",
                        buf[MCI_BLKR / 4],
                        buf[MCI_BLKR / 4] & 0xffff,
                        (buf[MCI_BLKR / 4] >> 16) & 0xffff);

        /* Don't read RSPR and RDR; it will consume the data there */

        atmci_show_status_reg(s, "SR", buf[MCI_SR / 4]);
        atmci_show_status_reg(s, "IMR", buf[MCI_IMR / 4]);

        kfree(buf);

        return 0;
}

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

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

static void atmci_init_debugfs(struct atmel_mci_slot *slot)
{
        struct mmc_host         *mmc = slot->mmc;
        struct atmel_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,
                        &atmci_regs_fops);
        if (IS_ERR(node))
                return;
        if (!node)
                goto err;

        node = debugfs_create_file("req", S_IRUSR, root, slot, &atmci_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");
}

static inline unsigned int ns_to_clocks(struct atmel_mci *host,
                                        unsigned int ns)
{
        return (ns * (host->bus_hz / 1000000) + 999) / 1000;
}

static void atmci_set_timeout(struct atmel_mci *host,
                struct atmel_mci_slot *slot, struct mmc_data *data)
{
        static unsigned dtomul_to_shift[] = {
                0, 4, 7, 8, 10, 12, 16, 20
        };
        unsigned        timeout;
        unsigned        dtocyc;
        unsigned        dtomul;

        timeout = ns_to_clocks(host, data->timeout_ns) + data->timeout_clks;

        for (dtomul = 0; dtomul < 8; dtomul++) {
                unsigned shift = dtomul_to_shift[dtomul];
                dtocyc = (timeout + (1 << shift) - 1) >> shift;
                if (dtocyc < 15)
                        break;
        }

        if (dtomul >= 8) {
                dtomul = 7;
                dtocyc = 15;
        }

        dev_vdbg(&slot->mmc->class_dev, "setting timeout to %u cycles\n",
                        dtocyc << dtomul_to_shift[dtomul]);
        mci_writel(host, DTOR, (MCI_DTOMUL(dtomul) | MCI_DTOCYC(dtocyc)));
}

/*
 * Return mask with command flags to be enabled for this command.
 */
static u32 atmci_prepare_command(struct mmc_host *mmc,
                                 struct mmc_command *cmd)
{
        struct mmc_data *data;
        u32             cmdr;

        cmd->error = -EINPROGRESS;

        cmdr = MCI_CMDR_CMDNB(cmd->opcode);

        if (cmd->flags & MMC_RSP_PRESENT) {
                if (cmd->flags & MMC_RSP_136)
                        cmdr |= MCI_CMDR_RSPTYP_136BIT;
                else
                        cmdr |= MCI_CMDR_RSPTYP_48BIT;
        }

        /*
         * This should really be MAXLAT_5 for CMD2 and ACMD41, but
         * it's too difficult to determine whether this is an ACMD or
         * not. Better make it 64.
         */
        cmdr |= MCI_CMDR_MAXLAT_64CYC;

        if (mmc->ios.bus_mode == MMC_BUSMODE_OPENDRAIN)
                cmdr |= MCI_CMDR_OPDCMD;

        data = cmd->data;
        if (data) {
                cmdr |= MCI_CMDR_START_XFER;
                if (data->flags & MMC_DATA_STREAM)
                        cmdr |= MCI_CMDR_STREAM;
                else if (data->blocks > 1)
                        cmdr |= MCI_CMDR_MULTI_BLOCK;
                else
                        cmdr |= MCI_CMDR_BLOCK;

                if (data->flags & MMC_DATA_READ)
                        cmdr |= MCI_CMDR_TRDIR_READ;
        }

        return cmdr;
}

static void atmci_start_command(struct atmel_mci *host,
                struct mmc_command *cmd, u32 cmd_flags)
{
        WARN_ON(host->cmd);
        host->cmd = cmd;

        dev_vdbg(&host->pdev->dev,
                        "start command: ARGR=0x%08x CMDR=0x%08x\n",
                        cmd->arg, cmd_flags);

        mci_writel(host, ARGR, cmd->arg);
        mci_writel(host, CMDR, cmd_flags);
}

static void send_stop_cmd(struct atmel_mci *host, struct mmc_data *data)
{
        atmci_start_command(host, data->stop, host->stop_cmdr);
        mci_writel(host, IER, MCI_CMDRDY);
}

#ifdef CONFIG_MMC_ATMELMCI_DMA
static void atmci_dma_cleanup(struct atmel_mci *host)
{
        struct mmc_data                 *data = host->data;

        dma_unmap_sg(&host->pdev->dev, data->sg, data->sg_len,
                     ((data->flags & MMC_DATA_WRITE)
                      ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
}

static void atmci_stop_dma(struct atmel_mci *host)
{
        struct dma_chan *chan = host->data_chan;

        if (chan) {
                chan->device->device_terminate_all(chan);
                atmci_dma_cleanup(host);
        } else {
                /* Data transfer was stopped by the interrupt handler */
                atmci_set_pending(host, EVENT_XFER_COMPLETE);
                mci_writel(host, IER, MCI_NOTBUSY);
        }
}

/* This function is called by the DMA driver from tasklet context. */
static void atmci_dma_complete(void *arg)
{
        struct atmel_mci        *host = arg;
        struct mmc_data         *data = host->data;

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

        atmci_dma_cleanup(host);

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

                /*
                 * Regardless of what the documentation says, we have
                 * to wait for NOTBUSY even after block read
                 * operations.
                 *
                 * When the DMA transfer is complete, the controller
                 * may still be reading the CRC from the card, i.e.
                 * the data transfer is still in progress and we
                 * haven't seen all the potential error bits yet.
                 *
                 * The interrupt handler will schedule a different
                 * tasklet to finish things up when the data transfer
                 * is completely done.
                 *
                 * We may not complete the mmc request here anyway
                 * because the mmc layer may call back and cause us to
                 * violate the "don't submit new operations from the
                 * completion callback" rule of the dma engine
                 * framework.
                 */
                mci_writel(host, IER, MCI_NOTBUSY);
        }
}

static int
atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data)
{
        struct dma_chan                 *chan;
        struct dma_async_tx_descriptor  *desc;
        struct scatterlist              *sg;
        unsigned int                    i;
        enum dma_data_direction         direction;

        /*
         * 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 < ATMCI_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;
        }

        /* If we don't have a channel, we can't do DMA */
        chan = host->dma.chan;
        if (chan)
                host->data_chan = chan;

        if (!chan)
                return -ENODEV;

        if (data->flags & MMC_DATA_READ)
                direction = DMA_FROM_DEVICE;
        else
                direction = DMA_TO_DEVICE;

        desc = chan->device->device_prep_slave_sg(chan,
                        data->sg, data->sg_len, direction,
                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!desc)
                return -ENOMEM;

        host->dma.data_desc = desc;
        desc->callback = atmci_dma_complete;
        desc->callback_param = host;
        desc->tx_submit(desc);

        /* Go! */
        chan->device->device_issue_pending(chan);

        return 0;
}

#else /* CONFIG_MMC_ATMELMCI_DMA */

static int atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data)
{
        return -ENOSYS;
}

static void atmci_stop_dma(struct atmel_mci *host)
{
        /* Data transfer was stopped by the interrupt handler */
        atmci_set_pending(host, EVENT_XFER_COMPLETE);
        mci_writel(host, IER, MCI_NOTBUSY);
}

#endif /* CONFIG_MMC_ATMELMCI_DMA */

/*
 * Returns a mask of interrupt flags to be enabled after the whole
 * request has been prepared.
 */
static u32 atmci_submit_data(struct atmel_mci *host, struct mmc_data *data)
{
        u32 iflags;

        data->error = -EINPROGRESS;

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

        iflags = ATMCI_DATA_ERROR_FLAGS;
        if (atmci_submit_data_dma(host, data)) {
                host->data_chan = NULL;

                /*
                 * Errata: MMC data write operation with less than 12
                 * bytes is impossible.
                 *
                 * Errata: MCI Transmit Data Register (TDR) FIFO
                 * corruption when length is not multiple of 4.
                 */
                if (data->blocks * data->blksz < 12
                                || (data->blocks * data->blksz) & 3)
                        host->need_reset = true;

                host->sg = data->sg;
                host->pio_offset = 0;
                if (data->flags & MMC_DATA_READ)
                        iflags |= MCI_RXRDY;
                else
                        iflags |= MCI_TXRDY;
        }

        return iflags;
}

static void atmci_start_request(struct atmel_mci *host,
                struct atmel_mci_slot *slot)
{
        struct mmc_request      *mrq;
        struct mmc_command      *cmd;
        struct mmc_data         *data;
        u32                     iflags;
        u32                     cmdflags;

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

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

        if (host->need_reset) {
                mci_writel(host, CR, MCI_CR_SWRST);
                mci_writel(host, CR, MCI_CR_MCIEN);
                mci_writel(host, MR, host->mode_reg);
                host->need_reset = false;
        }
        mci_writel(host, SDCR, slot->sdc_reg);

        iflags = mci_readl(host, IMR);
        if (iflags)
                dev_warn(&slot->mmc->class_dev, "WARNING: IMR=0x%08x\n",
                                iflags);

        if (unlikely(test_and_clear_bit(ATMCI_CARD_NEED_INIT, &slot->flags))) {
                /* Send init sequence (74 clock cycles) */
                mci_writel(host, CMDR, MCI_CMDR_SPCMD_INIT);
                while (!(mci_readl(host, SR) & MCI_CMDRDY))
                        cpu_relax();
        }
        data = mrq->data;
        if (data) {
                atmci_set_timeout(host, slot, data);

                /* Must set block count/size before sending command */
                mci_writel(host, BLKR, MCI_BCNT(data->blocks)
                                | MCI_BLKLEN(data->blksz));
                dev_vdbg(&slot->mmc->class_dev, "BLKR=0x%08x\n",
                        MCI_BCNT(data->blocks) | MCI_BLKLEN(data->blksz));
        }

        iflags = MCI_CMDRDY;
        cmd = mrq->cmd;
        cmdflags = atmci_prepare_command(slot->mmc, cmd);
        atmci_start_command(host, cmd, cmdflags);

        if (data)
                iflags |= atmci_submit_data(host, data);

        if (mrq->stop) {
                host->stop_cmdr = atmci_prepare_command(slot->mmc, mrq->stop);
                host->stop_cmdr |= MCI_CMDR_STOP_XFER;
                if (!(data->flags & MMC_DATA_WRITE))
                        host->stop_cmdr |= MCI_CMDR_TRDIR_READ;
                if (data->flags & MMC_DATA_STREAM)
                        host->stop_cmdr |= MCI_CMDR_STREAM;
                else
                        host->stop_cmdr |= MCI_CMDR_MULTI_BLOCK;
        }

        /*
         * We could have enabled interrupts earlier, but I suspect
         * that would open up a nice can of interesting race
         * conditions (e.g. command and data complete, but stop not
         * prepared yet.)
         */
        mci_writel(host, IER, iflags);
}

static void atmci_queue_request(struct atmel_mci *host,
                struct atmel_mci_slot *slot, struct mmc_request *mrq)
{
        dev_vdbg(&slot->mmc->class_dev, "queue request: state=%d\n",
                        host->state);

        spin_lock_bh(&host->lock);
        slot->mrq = mrq;
        if (host->state == STATE_IDLE) {
                host->state = STATE_SENDING_CMD;
                atmci_start_request(host, slot);
        } else {
                list_add_tail(&slot->queue_node, &host->queue);
        }
        spin_unlock_bh(&host->lock);
}

static void atmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
        struct atmel_mci_slot   *slot = mmc_priv(mmc);
        struct atmel_mci        *host = slot->host;
        struct mmc_data         *data;

        WARN_ON(slot->mrq);

        /*
         * We may "know" the card is gone even though there's still an
         * electrical connection. If so, we really need to communicate
         * this to the MMC core since there won't be any more
         * interrupts as the card is completely removed. Otherwise,
         * the MMC core might believe the card is still there even
         * though the card was just removed very slowly.
         */
        if (!test_bit(ATMCI_CARD_PRESENT, &slot->flags)) {
                mrq->cmd->error = -ENOMEDIUM;
                mmc_request_done(mmc, mrq);
                return;
        }

        /* We don't support multiple blocks of weird lengths. */
        data = mrq->data;
        if (data && data->blocks > 1 && data->blksz & 3) {
                mrq->cmd->error = -EINVAL;
                mmc_request_done(mmc, mrq);
        }

        atmci_queue_request(host, slot, mrq);
}

static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
        struct atmel_mci_slot   *slot = mmc_priv(mmc);
        struct atmel_mci        *host = slot->host;
        unsigned int            i;

        slot->sdc_reg &= ~MCI_SDCBUS_MASK;
        switch (ios->bus_width) {
        case MMC_BUS_WIDTH_1:
                slot->sdc_reg |= MCI_SDCBUS_1BIT;
                break;
        case MMC_BUS_WIDTH_4:
                slot->sdc_reg = MCI_SDCBUS_4BIT;
                break;
        }

        if (ios->clock) {
                unsigned int clock_min = ~0U;
                u32 clkdiv;

                spin_lock_bh(&host->lock);
                if (!host->mode_reg) {
                        clk_enable(host->mck);
                        mci_writel(host, CR, MCI_CR_SWRST);
                        mci_writel(host, CR, MCI_CR_MCIEN);
                }

                /*
                 * Use mirror of ios->clock to prevent race with mmc
                 * core ios update when finding the minimum.
                 */
                slot->clock = ios->clock;
                for (i = 0; i < ATMEL_MCI_MAX_NR_SLOTS; i++) {
                        if (host->slot[i] && host->slot[i]->clock
                                        && host->slot[i]->clock < clock_min)
                                clock_min = host->slot[i]->clock;
                }

                /* Calculate clock divider */
                clkdiv = DIV_ROUND_UP(host->bus_hz, 2 * clock_min) - 1;
                if (clkdiv > 255) {
                        dev_warn(&mmc->class_dev,
                                "clock %u too slow; using %lu\n",
                                clock_min, host->bus_hz / (2 * 256));
                        clkdiv = 255;
                }

                /*
                 * WRPROOF and RDPROOF prevent overruns/underruns by
                 * stopping the clock when the FIFO is full/empty.
                 * This state is not expected to last for long.
                 */
                host->mode_reg = MCI_MR_CLKDIV(clkdiv) | MCI_MR_WRPROOF
                                        | MCI_MR_RDPROOF;

                if (list_empty(&host->queue))
                        mci_writel(host, MR, host->mode_reg);
                else
                        host->need_clock_update = true;

                spin_unlock_bh(&host->lock);
        } else {
                bool any_slot_active = false;

                spin_lock_bh(&host->lock);
                slot->clock = 0;
                for (i = 0; i < ATMEL_MCI_MAX_NR_SLOTS; i++) {
                        if (host->slot[i] && host->slot[i]->clock) {
                                any_slot_active = true;
                                break;
                        }
                }
                if (!any_slot_active) {
                        mci_writel(host, CR, MCI_CR_MCIDIS);
                        if (host->mode_reg) {
                                mci_readl(host, MR);
                                clk_disable(host->mck);
                        }
                        host->mode_reg = 0;
                }
                spin_unlock_bh(&host->lock);
        }

        switch (ios->power_mode) {
        case MMC_POWER_UP:
                set_bit(ATMCI_CARD_NEED_INIT, &slot->flags);
                break;
        default:
                /*
                 * TODO: None of the currently available AVR32-based
                 * boards allow MMC power to be turned off. Implement
                 * power control when this can be tested properly.
                 *
                 * We also need to hook this into the clock management
                 * somehow so that newly inserted cards aren't
                 * subjected to a fast clock before we have a chance
                 * to figure out what the maximum rate is. Currently,
                 * there's no way to avoid this, and there never will
                 * be for boards that don't support power control.
                 */
                break;
        }
}

static int atmci_get_ro(struct mmc_host *mmc)
{
        int                     read_only = -ENOSYS;
        struct atmel_mci_slot   *slot = mmc_priv(mmc);

        if (gpio_is_valid(slot->wp_pin)) {
                read_only = gpio_get_value(slot->wp_pin);
                dev_dbg(&mmc->class_dev, "card is %s\n",
                                read_only ? "read-only" : "read-write");
        }

        return read_only;
}

static int atmci_get_cd(struct mmc_host *mmc)
{
        int                     present = -ENOSYS;
        struct atmel_mci_slot   *slot = mmc_priv(mmc);

        if (gpio_is_valid(slot->detect_pin)) {
                present = !gpio_get_value(slot->detect_pin);
                dev_dbg(&mmc->class_dev, "card is %spresent\n",
                                present ? "" : "not ");
        }

        return present;
}

static const struct mmc_host_ops atmci_ops = {
        .request        = atmci_request,
        .set_ios        = atmci_set_ios,
        .get_ro         = atmci_get_ro,
        .get_cd         = atmci_get_cd,
};

/* Called with host->lock held */
static void atmci_request_end(struct atmel_mci *host, struct mmc_request *mrq)
        __releases(&host->lock)
        __acquires(&host->lock)
{
        struct atmel_mci_slot   *slot = NULL;
        struct mmc_host         *prev_mmc = host->cur_slot->mmc;

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

        /*
         * Update the MMC clock rate if necessary. This may be
         * necessary if set_ios() is called when a different slot is
         * busy transfering data.
         */
        if (host->need_clock_update)
                mci_writel(host, MR, host->mode_reg);

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

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

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

        /* Read the response from the card (up to 16 bytes) */
        cmd->resp[0] = mci_readl(host, RSPR);
        cmd->resp[1] = mci_readl(host, RSPR);
        cmd->resp[2] = mci_readl(host, RSPR);
        cmd->resp[3] = mci_readl(host, RSPR);

        if (status & MCI_RTOE)
                cmd->error = -ETIMEDOUT;
        else if ((cmd->flags & MMC_RSP_CRC) && (status & MCI_RCRCE))
                cmd->error = -EILSEQ;
        else if (status & (MCI_RINDE | MCI_RDIRE | MCI_RENDE))
                cmd->error = -EIO;
        else
                cmd->error = 0;

        if (cmd->error) {
                dev_dbg(&host->pdev->dev,
                        "command error: status=0x%08x\n", status);

                if (cmd->data) {
                        host->data = NULL;
                        atmci_stop_dma(host);
                        mci_writel(host, IDR, MCI_NOTBUSY
                                        | MCI_TXRDY | MCI_RXRDY
                                        | ATMCI_DATA_ERROR_FLAGS);
                }
        }
}

static void atmci_detect_change(unsigned long data)
{
        struct atmel_mci_slot   *slot = (struct atmel_mci_slot *)data;
        bool                    present;
        bool                    present_old;

        /*
         * atmci_cleanup_slot() sets the ATMCI_SHUTDOWN flag before
         * freeing the interrupt. We must not re-enable the interrupt
         * if it has been freed, and if we're shutting down, it
         * doesn't really matter whether the card is present or not.
         */
        smp_rmb();
        if (test_bit(ATMCI_SHUTDOWN, &slot->flags))
                return;

        enable_irq(gpio_to_irq(slot->detect_pin));
        present = !gpio_get_value(slot->detect_pin);
        present_old = test_bit(ATMCI_CARD_PRESENT, &slot->flags);

        dev_vdbg(&slot->mmc->class_dev, "detect change: %d (was %d)\n",
                        present, present_old);

        if (present != present_old) {
                struct atmel_mci        *host = slot->host;
                struct mmc_request      *mrq;

                dev_dbg(&slot->mmc->class_dev, "card %s\n",
                        present ? "inserted" : "removed");

                spin_lock(&host->lock);

                if (!present)
                        clear_bit(ATMCI_CARD_PRESENT, &slot->flags);
                else
                        set_bit(ATMCI_CARD_PRESENT, &slot->flags);

                /* Clean up queue if present */
                mrq = slot->mrq;
                if (mrq) {
                        if (mrq == host->mrq) {
                                /*
                                 * Reset controller to terminate any ongoing
                                 * commands or data transfers.
                                 */
                                mci_writel(host, CR, MCI_CR_SWRST);
                                mci_writel(host, CR, MCI_CR_MCIEN);
                                mci_writel(host, MR, host->mode_reg);

                                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;
                                        atmci_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;
                                }

                                atmci_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);
                        }
                }
                spin_unlock(&host->lock);

                mmc_detect_change(slot->mmc, 0);
        }
}

static void atmci_tasklet_func(unsigned long priv)
{
        struct atmel_mci        *host = (struct atmel_mci *)priv;
        struct mmc_request      *mrq = host->mrq;
        struct mmc_data         *data = host->data;
        struct mmc_command      *cmd = host->cmd;
        enum atmel_mci_state    state = host->state;
        enum atmel_mci_state    prev_state;
        u32                     status;

        spin_lock(&host->lock);

        state = host->state;

        dev_vdbg(&host->pdev->dev,
                "tasklet: state %u pending/completed/mask %lx/%lx/%x\n",
                state, host->pending_events, host->completed_events,
                mci_readl(host, IMR));

        do {
                prev_state = state;

                switch (state) {
                case STATE_IDLE:
                        break;

                case STATE_SENDING_CMD:
                        if (!atmci_test_and_clear_pending(host,
                                                EVENT_CMD_COMPLETE))
                                break;

                        host->cmd = NULL;
                        atmci_set_completed(host, EVENT_CMD_COMPLETE);
                        atmci_command_complete(host, mrq->cmd);
                        if (!mrq->data || cmd->error) {
                                atmci_request_end(host, host->mrq);
                                goto unlock;
                        }

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

                case STATE_SENDING_DATA:
                        if (atmci_test_and_clear_pending(host,
                                                EVENT_DATA_ERROR)) {
                                atmci_stop_dma(host);
                                if (data->stop)
                                        send_stop_cmd(host, data);
                                state = STATE_DATA_ERROR;
                                break;
                        }

                        if (!atmci_test_and_clear_pending(host,
                                                EVENT_XFER_COMPLETE))
                                break;

                        atmci_set_completed(host, EVENT_XFER_COMPLETE);
                        prev_state = state = STATE_DATA_BUSY;
                        /* fall through */

                case STATE_DATA_BUSY:
                        if (!atmci_test_and_clear_pending(host,
                                                EVENT_DATA_COMPLETE))
                                break;

                        host->data = NULL;
                        atmci_set_completed(host, EVENT_DATA_COMPLETE);
                        status = host->data_status;
                        if (unlikely(status & ATMCI_DATA_ERROR_FLAGS)) {
                                if (status & MCI_DTOE) {
                                        dev_dbg(&host->pdev->dev,
                                                        "data timeout error\n");
                                        data->error = -ETIMEDOUT;
                                } else if (status & MCI_DCRCE) {
                                        dev_dbg(&host->pdev->dev,
                                                        "data CRC error\n");
                                        data->error = -EILSEQ;
                                } else {
                                        dev_dbg(&host->pdev->dev,
                                                "data FIFO error (status=%08x)\n",
                                                status);
                                        data->error = -EIO;
                                }
                        } else {
                                data->bytes_xfered = data->blocks * data->blksz;
                                data->error = 0;
                        }

                        if (!data->stop) {
                                atmci_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 (!atmci_test_and_clear_pending(host,
                                                EVENT_CMD_COMPLETE))
                                break;

                        host->cmd = NULL;
                        atmci_command_complete(host, mrq->stop);
                        atmci_request_end(host, host->mrq);
                        goto unlock;

                case STATE_DATA_ERROR:
                        if (!atmci_test_and_clear_pending(host,
                                                EVENT_XFER_COMPLETE))
                                break;

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

        host->state = state;

unlock:
        spin_unlock(&host->lock);
}

static void atmci_read_data_pio(struct atmel_mci *host)
{
        struct scatterlist      *sg = host->sg;
        void                    *buf = sg_virt(sg);
        unsigned int            offset = host->pio_offset;
        struct mmc_data         *data = host->data;
        u32                     value;
        u32                     status;
        unsigned int            nbytes = 0;

        do {
                value = mci_readl(host, RDR);
                if (likely(offset + 4 <= sg->length)) {
                        put_unaligned(value, (u32 *)(buf + offset));

                        offset += 4;
                        nbytes += 4;

                        if (offset == sg->length) {
                                flush_dcache_page(sg_page(sg));
                                host->sg = sg = sg_next(sg);
                                if (!sg)
                                        goto done;

                                offset = 0;
                                buf = sg_virt(sg);
                        }
                } else {
                        unsigned int remaining = sg->length - offset;
                        memcpy(buf + offset, &value, remaining);
                        nbytes += remaining;

                        flush_dcache_page(sg_page(sg));
                        host->sg = sg = sg_next(sg);
                        if (!sg)
                                goto done;

                        offset = 4 - remaining;
                        buf = sg_virt(sg);
                        memcpy(buf, (u8 *)&value + remaining, offset);
                        nbytes += offset;
                }

                status = mci_readl(host, SR);
                if (status & ATMCI_DATA_ERROR_FLAGS) {
                        mci_writel(host, IDR, (MCI_NOTBUSY | MCI_RXRDY
                                                | ATMCI_DATA_ERROR_FLAGS));
                        host->data_status = status;
                        data->bytes_xfered += nbytes;
                        smp_wmb();
                        atmci_set_pending(host, EVENT_DATA_ERROR);
                        tasklet_schedule(&host->tasklet);
                        return;
                }
        } while (status & MCI_RXRDY);

        host->pio_offset = offset;
        data->bytes_xfered += nbytes;

        return;

done:
        mci_writel(host, IDR, MCI_RXRDY);
        mci_writel(host, IER, MCI_NOTBUSY);
        data->bytes_xfered += nbytes;
        smp_wmb();
        atmci_set_pending(host, EVENT_XFER_COMPLETE);
}

static void atmci_write_data_pio(struct atmel_mci *host)
{
        struct scatterlist      *sg = host->sg;
        void                    *buf = sg_virt(sg);
        unsigned int            offset = host->pio_offset;
        struct mmc_data         *data = host->data;
        u32                     value;
        u32                     status;
        unsigned int            nbytes = 0;

        do {
                if (likely(offset + 4 <= sg->length)) {
                        value = get_unaligned((u32 *)(buf + offset));
                        mci_writel(host, TDR, value);

                        offset += 4;
                        nbytes += 4;
                        if (offset == sg->length) {
                                host->sg = sg = sg_next(sg);
                                if (!sg)
                                        goto done;

                                offset = 0;
                                buf = sg_virt(sg);
                        }
                } else {
                        unsigned int remaining = sg->length - offset;

                        value = 0;
                        memcpy(&value, buf + offset, remaining);
                        nbytes += remaining;

                        host->sg = sg = sg_next(sg);
                        if (!sg) {
                                mci_writel(host, TDR, value);
                                goto done;
                        }

                        offset = 4 - remaining;
                        buf = sg_virt(sg);
                        memcpy((u8 *)&value + remaining, buf, offset);
                        mci_writel(host, TDR, value);
                        nbytes += offset;
                }

                status = mci_readl(host, SR);
                if (status & ATMCI_DATA_ERROR_FLAGS) {
                        mci_writel(host, IDR, (MCI_NOTBUSY | MCI_TXRDY
                                                | ATMCI_DATA_ERROR_FLAGS));
                        host->data_status = status;
                        data->bytes_xfered += nbytes;
                        smp_wmb();
                        atmci_set_pending(host, EVENT_DATA_ERROR);
                        tasklet_schedule(&host->tasklet);
                        return;
                }
        } while (status & MCI_TXRDY);

        host->pio_offset = offset;
        data->bytes_xfered += nbytes;

        return;

done:
        mci_writel(host, IDR, MCI_TXRDY);
        mci_writel(host, IER, MCI_NOTBUSY);
        data->bytes_xfered += nbytes;
        smp_wmb();
        atmci_set_pending(host, EVENT_XFER_COMPLETE);
}

static void atmci_cmd_interrupt(struct atmel_mci *host, u32 status)
{
        mci_writel(host, IDR, MCI_CMDRDY);

        host->cmd_status = status;
        smp_wmb();
        atmci_set_pending(host, EVENT_CMD_COMPLETE);
        tasklet_schedule(&host->tasklet);
}

static irqreturn_t atmci_interrupt(int irq, void *dev_id)
{
        struct atmel_mci        *host = dev_id;
        u32                     status, mask, pending;
        unsigned int            pass_count = 0;

        do {
                status = mci_readl(host, SR);
                mask = mci_readl(host, IMR);
                pending = status & mask;
                if (!pending)
                        break;

                if (pending & ATMCI_DATA_ERROR_FLAGS) {
                        mci_writel(host, IDR, ATMCI_DATA_ERROR_FLAGS
                                        | MCI_RXRDY | MCI_TXRDY);
                        pending &= mci_readl(host, IMR);

                        host->data_status = status;
                        smp_wmb();
                        atmci_set_pending(host, EVENT_DATA_ERROR);
                        tasklet_schedule(&host->tasklet);
                }
                if (pending & MCI_NOTBUSY) {
                        mci_writel(host, IDR,
                                        ATMCI_DATA_ERROR_FLAGS | MCI_NOTBUSY);
                        if (!host->data_status)
                                host->data_status = status;
                        smp_wmb();
                        atmci_set_pending(host, EVENT_DATA_COMPLETE);
                        tasklet_schedule(&host->tasklet);
                }
                if (pending & MCI_RXRDY)
                        atmci_read_data_pio(host);
                if (pending & MCI_TXRDY)
                        atmci_write_data_pio(host);

                if (pending & MCI_CMDRDY)
                        atmci_cmd_interrupt(host, status);
        } while (pass_count++ < 5);

        return pass_count ? IRQ_HANDLED : IRQ_NONE;
}

static irqreturn_t atmci_detect_interrupt(int irq, void *dev_id)
{
        struct atmel_mci_slot   *slot = dev_id;

        /*
         * Disable interrupts until the pin has stabilized and check
         * the state then. Use mod_timer() since we may be in the
         * middle of the timer routine when this interrupt triggers.
         */
        disable_irq_nosync(irq);
        mod_timer(&slot->detect_timer, jiffies + msecs_to_jiffies(20));

        return IRQ_HANDLED;
}

static int __init atmci_init_slot(struct atmel_mci *host,
                struct mci_slot_pdata *slot_data, unsigned int id,
                u32 sdc_reg)
{
        struct mmc_host                 *mmc;
        struct atmel_mci_slot           *slot;

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

        slot = mmc_priv(mmc);
        slot->mmc = mmc;
        slot->host = host;
        slot->detect_pin = slot_data->detect_pin;
        slot->wp_pin = slot_data->wp_pin;
        slot->sdc_reg = sdc_reg;

        mmc->ops = &atmci_ops;
        mmc->f_min = DIV_ROUND_UP(host->bus_hz, 512);
        mmc->f_max = host->bus_hz / 2;
        mmc->ocr_avail  = MMC_VDD_32_33 | MMC_VDD_33_34;
        if (slot_data->bus_width >= 4)
                mmc->caps |= MMC_CAP_4_BIT_DATA;

        mmc->max_hw_segs = 64;
        mmc->max_phys_segs = 64;
        mmc->max_req_size = 32768 * 512;
        mmc->max_blk_size = 32768;
        mmc->max_blk_count = 512;

        /* Assume card is present initially */
        set_bit(ATMCI_CARD_PRESENT, &slot->flags);
        if (gpio_is_valid(slot->detect_pin)) {
                if (gpio_request(slot->detect_pin, "mmc_detect")) {
                        dev_dbg(&mmc->class_dev, "no detect pin available\n");
                        slot->detect_pin = -EBUSY;
                } else if (gpio_get_value(slot->detect_pin)) {
                        clear_bit(ATMCI_CARD_PRESENT, &slot->flags);
                }
        }

        if (!gpio_is_valid(slot->detect_pin))
                mmc->caps |= MMC_CAP_NEEDS_POLL;

        if (gpio_is_valid(slot->wp_pin)) {
                if (gpio_request(slot->wp_pin, "mmc_wp")) {
                        dev_dbg(&mmc->class_dev, "no WP pin available\n");
                        slot->wp_pin = -EBUSY;
                }
        }

        host->slot[id] = slot;
        mmc_add_host(mmc);

        if (gpio_is_valid(slot->detect_pin)) {
                int ret;

                setup_timer(&slot->detect_timer, atmci_detect_change,
                                (unsigned long)slot);

                ret = request_irq(gpio_to_irq(slot->detect_pin),
                                atmci_detect_interrupt,
                                IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
                                "mmc-detect", slot);
                if (ret) {
                        dev_dbg(&mmc->class_dev,
                                "could not request IRQ %d for detect pin\n",
                                gpio_to_irq(slot->detect_pin));
                        gpio_free(slot->detect_pin);
                        slot->detect_pin = -EBUSY;
                }
        }

        atmci_init_debugfs(slot);

        return 0;
}

static void __exit atmci_cleanup_slot(struct atmel_mci_slot *slot,
                unsigned int id)
{
        /* Debugfs stuff is cleaned up by mmc core */

        set_bit(ATMCI_SHUTDOWN, &slot->flags);
        smp_wmb();

        mmc_remove_host(slot->mmc);

        if (gpio_is_valid(slot->detect_pin)) {
                int pin = slot->detect_pin;

                free_irq(gpio_to_irq(pin), slot);
                del_timer_sync(&slot->detect_timer);
                gpio_free(pin);
        }
        if (gpio_is_valid(slot->wp_pin))
                gpio_free(slot->wp_pin);

        slot->host->slot[id] = NULL;
        mmc_free_host(slot->mmc);
}

#ifdef CONFIG_MMC_ATMELMCI_DMA
static bool filter(struct dma_chan *chan, void *slave)
{
        struct dw_dma_slave *dws = slave;

        if (dws->dma_dev == chan->device->dev) {
                chan->private = dws;
                return true;
        } else
                return false;
}
#endif

static int __init atmci_probe(struct platform_device *pdev)
{
        struct mci_platform_data        *pdata;
        struct atmel_mci                *host;
        struct resource                 *regs;
        unsigned int                    nr_slots;
        int                             irq;
        int                             ret;

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!regs)
                return -ENXIO;
        pdata = pdev->dev.platform_data;
        if (!pdata)
                return -ENXIO;
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        host = kzalloc(sizeof(struct atmel_mci), GFP_KERNEL);
        if (!host)
                return -ENOMEM;

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

        host->mck = clk_get(&pdev->dev, "mci_clk");
        if (IS_ERR(host->mck)) {
                ret = PTR_ERR(host->mck);
                goto err_clk_get;
        }

        ret = -ENOMEM;
        host->regs = ioremap(regs->start, regs->end - regs->start + 1);
        if (!host->regs)
                goto err_ioremap;

        clk_enable(host->mck);
        mci_writel(host, CR, MCI_CR_SWRST);
        host->bus_hz = clk_get_rate(host->mck);
        clk_disable(host->mck);

        host->mapbase = regs->start;

        tasklet_init(&host->tasklet, atmci_tasklet_func, (unsigned long)host);

        ret = request_irq(irq, atmci_interrupt, 0, pdev->dev.bus_id, host);
        if (ret)
                goto err_request_irq;

#ifdef CONFIG_MMC_ATMELMCI_DMA
        if (pdata->dma_slave.dma_dev) {
                struct dw_dma_slave *dws = &pdata->dma_slave;
                dma_cap_mask_t mask;

                dws->tx_reg = regs->start + MCI_TDR;
                dws->rx_reg = regs->start + MCI_RDR;

                /* Try to grab a DMA channel */
                dma_cap_zero(mask);
                dma_cap_set(DMA_SLAVE, mask);
                host->dma.chan = dma_request_channel(mask, filter, dws);
        }
        if (!host->dma.chan)
                dev_notice(&pdev->dev, "DMA not available, using PIO\n");
#endif /* CONFIG_MMC_ATMELMCI_DMA */

        platform_set_drvdata(pdev, host);

        /* We need at least one slot to succeed */
        nr_slots = 0;
        ret = -ENODEV;
        if (pdata->slot[0].bus_width) {
                ret = atmci_init_slot(host, &pdata->slot[0],
                                MCI_SDCSEL_SLOT_A, 0);
                if (!ret)
                        nr_slots++;
        }
        if (pdata->slot[1].bus_width) {
                ret = atmci_init_slot(host, &pdata->slot[1],
                                MCI_SDCSEL_SLOT_B, 1);
                if (!ret)
                        nr_slots++;
        }

        if (!nr_slots)
                goto err_init_slot;

        dev_info(&pdev->dev,
                        "Atmel MCI controller at 0x%08lx irq %d, %u slots\n",
                        host->mapbase, irq, nr_slots);

        return 0;

err_init_slot:
#ifdef CONFIG_MMC_ATMELMCI_DMA
        if (host->dma.chan)
                dma_release_channel(host->dma.chan);
#endif
        free_irq(irq, host);
err_request_irq:
        iounmap(host->regs);
err_ioremap:
        clk_put(host->mck);
err_clk_get:
        kfree(host);
        return ret;
}

static int __exit atmci_remove(struct platform_device *pdev)
{
        struct atmel_mci        *host = platform_get_drvdata(pdev);
        unsigned int            i;

        platform_set_drvdata(pdev, NULL);

        for (i = 0; i < ATMEL_MCI_MAX_NR_SLOTS; i++) {
                if (host->slot[i])
                        atmci_cleanup_slot(host->slot[i], i);
        }

        clk_enable(host->mck);
        mci_writel(host, IDR, ~0UL);
        mci_writel(host, CR, MCI_CR_MCIDIS);
        mci_readl(host, SR);
        clk_disable(host->mck);

#ifdef CONFIG_MMC_ATMELMCI_DMA
        if (host->dma.chan)
                dma_release_channel(host->dma.chan);
#endif

        free_irq(platform_get_irq(pdev, 0), host);
        iounmap(host->regs);

        clk_put(host->mck);
        kfree(host);

        return 0;
}

static struct platform_driver atmci_driver = {
        .remove         = __exit_p(atmci_remove),
        .driver         = {
                .name           = "atmel_mci",
        },
};

static int __init atmci_init(void)
{
        return platform_driver_probe(&atmci_driver, atmci_probe);
}

static void __exit atmci_exit(void)
{
        platform_driver_unregister(&atmci_driver);
}

late_initcall(atmci_init); /* try to load after dma driver when built-in */
module_exit(atmci_exit);

MODULE_DESCRIPTION("Atmel Multimedia Card Interface driver");
MODULE_AUTHOR("Haavard Skinnemoen <haavard.skinnemoen@atmel.com>");
MODULE_LICENSE("GPL v2");