mm-only debug patch...

[mmotm.git] / drivers / dma / fsldma.c

/*
 * Freescale MPC85xx, MPC83xx DMA Engine support
 *
 * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
 *
 * Author:
 *   Zhang Wei <wei.zhang@freescale.com>, Jul 2007
 *   Ebony Zhu <ebony.zhu@freescale.com>, May 2007
 *
 * Description:
 *   DMA engine driver for Freescale MPC8540 DMA controller, which is
 *   also fit for MPC8560, MPC8555, MPC8548, MPC8641, and etc.
 *   The support for MPC8349 DMA contorller is also added.
 *
 * This driver instructs the DMA controller to issue the PCI Read Multiple
 * command for PCI read operations, instead of using the default PCI Read Line
 * command. Please be aware that this setting may result in read pre-fetching
 * on some platforms.
 *
 * This 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/init.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/dmaengine.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/of_platform.h>

#include <asm/fsldma.h>
#include "fsldma.h"

static void dma_init(struct fsl_dma_chan *fsl_chan)
{
        /* Reset the channel */
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr, 0, 32);

        switch (fsl_chan->feature & FSL_DMA_IP_MASK) {
        case FSL_DMA_IP_85XX:
                /* Set the channel to below modes:
                 * EIE - Error interrupt enable
                 * EOSIE - End of segments interrupt enable (basic mode)
                 * EOLNIE - End of links interrupt enable
                 */
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr, FSL_DMA_MR_EIE
                                | FSL_DMA_MR_EOLNIE | FSL_DMA_MR_EOSIE, 32);
                break;
        case FSL_DMA_IP_83XX:
                /* Set the channel to below modes:
                 * EOTIE - End-of-transfer interrupt enable
                 * PRC_RM - PCI read multiple
                 */
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr, FSL_DMA_MR_EOTIE
                                | FSL_DMA_MR_PRC_RM, 32);
                break;
        }

}

static void set_sr(struct fsl_dma_chan *fsl_chan, u32 val)
{
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->sr, val, 32);
}

static u32 get_sr(struct fsl_dma_chan *fsl_chan)
{
        return DMA_IN(fsl_chan, &fsl_chan->reg_base->sr, 32);
}

static void set_desc_cnt(struct fsl_dma_chan *fsl_chan,
                                struct fsl_dma_ld_hw *hw, u32 count)
{
        hw->count = CPU_TO_DMA(fsl_chan, count, 32);
}

static void set_desc_src(struct fsl_dma_chan *fsl_chan,
                                struct fsl_dma_ld_hw *hw, dma_addr_t src)
{
        u64 snoop_bits;

        snoop_bits = ((fsl_chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX)
                ? ((u64)FSL_DMA_SATR_SREADTYPE_SNOOP_READ << 32) : 0;
        hw->src_addr = CPU_TO_DMA(fsl_chan, snoop_bits | src, 64);
}

static void set_desc_dest(struct fsl_dma_chan *fsl_chan,
                                struct fsl_dma_ld_hw *hw, dma_addr_t dest)
{
        u64 snoop_bits;

        snoop_bits = ((fsl_chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX)
                ? ((u64)FSL_DMA_DATR_DWRITETYPE_SNOOP_WRITE << 32) : 0;
        hw->dst_addr = CPU_TO_DMA(fsl_chan, snoop_bits | dest, 64);
}

static void set_desc_next(struct fsl_dma_chan *fsl_chan,
                                struct fsl_dma_ld_hw *hw, dma_addr_t next)
{
        u64 snoop_bits;

        snoop_bits = ((fsl_chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_83XX)
                ? FSL_DMA_SNEN : 0;
        hw->next_ln_addr = CPU_TO_DMA(fsl_chan, snoop_bits | next, 64);
}

static void set_cdar(struct fsl_dma_chan *fsl_chan, dma_addr_t addr)
{
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->cdar, addr | FSL_DMA_SNEN, 64);
}

static dma_addr_t get_cdar(struct fsl_dma_chan *fsl_chan)
{
        return DMA_IN(fsl_chan, &fsl_chan->reg_base->cdar, 64) & ~FSL_DMA_SNEN;
}

static void set_ndar(struct fsl_dma_chan *fsl_chan, dma_addr_t addr)
{
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->ndar, addr, 64);
}

static dma_addr_t get_ndar(struct fsl_dma_chan *fsl_chan)
{
        return DMA_IN(fsl_chan, &fsl_chan->reg_base->ndar, 64);
}

static u32 get_bcr(struct fsl_dma_chan *fsl_chan)
{
        return DMA_IN(fsl_chan, &fsl_chan->reg_base->bcr, 32);
}

static int dma_is_idle(struct fsl_dma_chan *fsl_chan)
{
        u32 sr = get_sr(fsl_chan);
        return (!(sr & FSL_DMA_SR_CB)) || (sr & FSL_DMA_SR_CH);
}

static void dma_start(struct fsl_dma_chan *fsl_chan)
{
        u32 mr_set = 0;

        if (fsl_chan->feature & FSL_DMA_CHAN_PAUSE_EXT) {
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->bcr, 0, 32);
                mr_set |= FSL_DMA_MR_EMP_EN;
        } else if ((fsl_chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32)
                                & ~FSL_DMA_MR_EMP_EN, 32);
        }

        if (fsl_chan->feature & FSL_DMA_CHAN_START_EXT)
                mr_set |= FSL_DMA_MR_EMS_EN;
        else
                mr_set |= FSL_DMA_MR_CS;

        DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32)
                        | mr_set, 32);
}

static void dma_halt(struct fsl_dma_chan *fsl_chan)
{
        int i;

        DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) | FSL_DMA_MR_CA,
                32);
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) & ~(FSL_DMA_MR_CS
                | FSL_DMA_MR_EMS_EN | FSL_DMA_MR_CA), 32);

        for (i = 0; i < 100; i++) {
                if (dma_is_idle(fsl_chan))
                        break;
                udelay(10);
        }
        if (i >= 100 && !dma_is_idle(fsl_chan))
                dev_err(fsl_chan->dev, "DMA halt timeout!\n");
}

static void set_ld_eol(struct fsl_dma_chan *fsl_chan,
                        struct fsl_desc_sw *desc)
{
        u64 snoop_bits;

        snoop_bits = ((fsl_chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_83XX)
                ? FSL_DMA_SNEN : 0;

        desc->hw.next_ln_addr = CPU_TO_DMA(fsl_chan,
                DMA_TO_CPU(fsl_chan, desc->hw.next_ln_addr, 64) | FSL_DMA_EOL
                        | snoop_bits, 64);
}

static void append_ld_queue(struct fsl_dma_chan *fsl_chan,
                struct fsl_desc_sw *new_desc)
{
        struct fsl_desc_sw *queue_tail = to_fsl_desc(fsl_chan->ld_queue.prev);

        if (list_empty(&fsl_chan->ld_queue))
                return;

        /* Link to the new descriptor physical address and
         * Enable End-of-segment interrupt for
         * the last link descriptor.
         * (the previous node's next link descriptor)
         *
         * For FSL_DMA_IP_83xx, the snoop enable bit need be set.
         */
        queue_tail->hw.next_ln_addr = CPU_TO_DMA(fsl_chan,
                        new_desc->async_tx.phys | FSL_DMA_EOSIE |
                        (((fsl_chan->feature & FSL_DMA_IP_MASK)
                                == FSL_DMA_IP_83XX) ? FSL_DMA_SNEN : 0), 64);
}

/**
 * fsl_chan_set_src_loop_size - Set source address hold transfer size
 * @fsl_chan : Freescale DMA channel
 * @size     : Address loop size, 0 for disable loop
 *
 * The set source address hold transfer size. The source
 * address hold or loop transfer size is when the DMA transfer
 * data from source address (SA), if the loop size is 4, the DMA will
 * read data from SA, SA + 1, SA + 2, SA + 3, then loop back to SA,
 * SA + 1 ... and so on.
 */
static void fsl_chan_set_src_loop_size(struct fsl_dma_chan *fsl_chan, int size)
{
        switch (size) {
        case 0:
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) &
                        (~FSL_DMA_MR_SAHE), 32);
                break;
        case 1:
        case 2:
        case 4:
        case 8:
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) |
                        FSL_DMA_MR_SAHE | (__ilog2(size) << 14),
                        32);
                break;
        }
}

/**
 * fsl_chan_set_dest_loop_size - Set destination address hold transfer size
 * @fsl_chan : Freescale DMA channel
 * @size     : Address loop size, 0 for disable loop
 *
 * The set destination address hold transfer size. The destination
 * address hold or loop transfer size is when the DMA transfer
 * data to destination address (TA), if the loop size is 4, the DMA will
 * write data to TA, TA + 1, TA + 2, TA + 3, then loop back to TA,
 * TA + 1 ... and so on.
 */
static void fsl_chan_set_dest_loop_size(struct fsl_dma_chan *fsl_chan, int size)
{
        switch (size) {
        case 0:
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) &
                        (~FSL_DMA_MR_DAHE), 32);
                break;
        case 1:
        case 2:
        case 4:
        case 8:
                DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                        DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) |
                        FSL_DMA_MR_DAHE | (__ilog2(size) << 16),
                        32);
                break;
        }
}

/**
 * fsl_chan_set_request_count - Set DMA Request Count for external control
 * @fsl_chan : Freescale DMA channel
 * @size     : Number of bytes to transfer in a single request
 *
 * The Freescale DMA channel can be controlled by the external signal DREQ#.
 * The DMA request count is how many bytes are allowed to transfer before
 * pausing the channel, after which a new assertion of DREQ# resumes channel
 * operation.
 *
 * A size of 0 disables external pause control. The maximum size is 1024.
 */
static void fsl_chan_set_request_count(struct fsl_dma_chan *fsl_chan, int size)
{
        BUG_ON(size > 1024);
        DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
                DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32)
                        | ((__ilog2(size) << 24) & 0x0f000000),
                32);
}

/**
 * fsl_chan_toggle_ext_pause - Toggle channel external pause status
 * @fsl_chan : Freescale DMA channel
 * @enable   : 0 is disabled, 1 is enabled.
 *
 * The Freescale DMA channel can be controlled by the external signal DREQ#.
 * The DMA Request Count feature should be used in addition to this feature
 * to set the number of bytes to transfer before pausing the channel.
 */
static void fsl_chan_toggle_ext_pause(struct fsl_dma_chan *fsl_chan, int enable)
{
        if (enable)
                fsl_chan->feature |= FSL_DMA_CHAN_PAUSE_EXT;
        else
                fsl_chan->feature &= ~FSL_DMA_CHAN_PAUSE_EXT;
}

/**
 * fsl_chan_toggle_ext_start - Toggle channel external start status
 * @fsl_chan : Freescale DMA channel
 * @enable   : 0 is disabled, 1 is enabled.
 *
 * If enable the external start, the channel can be started by an
 * external DMA start pin. So the dma_start() does not start the
 * transfer immediately. The DMA channel will wait for the
 * control pin asserted.
 */
static void fsl_chan_toggle_ext_start(struct fsl_dma_chan *fsl_chan, int enable)
{
        if (enable)
                fsl_chan->feature |= FSL_DMA_CHAN_START_EXT;
        else
                fsl_chan->feature &= ~FSL_DMA_CHAN_START_EXT;
}

static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct fsl_dma_chan *fsl_chan = to_fsl_chan(tx->chan);
        struct fsl_desc_sw *desc = tx_to_fsl_desc(tx);
        struct fsl_desc_sw *child;
        unsigned long flags;
        dma_cookie_t cookie;

        /* cookie increment and adding to ld_queue must be atomic */
        spin_lock_irqsave(&fsl_chan->desc_lock, flags);

        cookie = fsl_chan->common.cookie;
        list_for_each_entry(child, &desc->tx_list, node) {
                cookie++;
                if (cookie < 0)
                        cookie = 1;

                desc->async_tx.cookie = cookie;
        }

        fsl_chan->common.cookie = cookie;
        append_ld_queue(fsl_chan, desc);
        list_splice_init(&desc->tx_list, fsl_chan->ld_queue.prev);

        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);

        return cookie;
}

/**
 * fsl_dma_alloc_descriptor - Allocate descriptor from channel's DMA pool.
 * @fsl_chan : Freescale DMA channel
 *
 * Return - The descriptor allocated. NULL for failed.
 */
static struct fsl_desc_sw *fsl_dma_alloc_descriptor(
                                        struct fsl_dma_chan *fsl_chan)
{
        dma_addr_t pdesc;
        struct fsl_desc_sw *desc_sw;

        desc_sw = dma_pool_alloc(fsl_chan->desc_pool, GFP_ATOMIC, &pdesc);
        if (desc_sw) {
                memset(desc_sw, 0, sizeof(struct fsl_desc_sw));
                INIT_LIST_HEAD(&desc_sw->tx_list);
                dma_async_tx_descriptor_init(&desc_sw->async_tx,
                                                &fsl_chan->common);
                desc_sw->async_tx.tx_submit = fsl_dma_tx_submit;
                desc_sw->async_tx.phys = pdesc;
        }

        return desc_sw;
}


/**
 * fsl_dma_alloc_chan_resources - Allocate resources for DMA channel.
 * @fsl_chan : Freescale DMA channel
 *
 * This function will create a dma pool for descriptor allocation.
 *
 * Return - The number of descriptors allocated.
 */
static int fsl_dma_alloc_chan_resources(struct dma_chan *chan)
{
        struct fsl_dma_chan *fsl_chan = to_fsl_chan(chan);

        /* Has this channel already been allocated? */
        if (fsl_chan->desc_pool)
                return 1;

        /* We need the descriptor to be aligned to 32bytes
         * for meeting FSL DMA specification requirement.
         */
        fsl_chan->desc_pool = dma_pool_create("fsl_dma_engine_desc_pool",
                        fsl_chan->dev, sizeof(struct fsl_desc_sw),
                        32, 0);
        if (!fsl_chan->desc_pool) {
                dev_err(fsl_chan->dev, "No memory for channel %d "
                        "descriptor dma pool.\n", fsl_chan->id);
                return 0;
        }

        return 1;
}

/**
 * fsl_dma_free_chan_resources - Free all resources of the channel.
 * @fsl_chan : Freescale DMA channel
 */
static void fsl_dma_free_chan_resources(struct dma_chan *chan)
{
        struct fsl_dma_chan *fsl_chan = to_fsl_chan(chan);
        struct fsl_desc_sw *desc, *_desc;
        unsigned long flags;

        dev_dbg(fsl_chan->dev, "Free all channel resources.\n");
        spin_lock_irqsave(&fsl_chan->desc_lock, flags);
        list_for_each_entry_safe(desc, _desc, &fsl_chan->ld_queue, node) {
#ifdef FSL_DMA_LD_DEBUG
                dev_dbg(fsl_chan->dev,
                                "LD %p will be released.\n", desc);
#endif
                list_del(&desc->node);
                /* free link descriptor */
                dma_pool_free(fsl_chan->desc_pool, desc, desc->async_tx.phys);
        }
        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
        dma_pool_destroy(fsl_chan->desc_pool);

        fsl_chan->desc_pool = NULL;
}

static struct dma_async_tx_descriptor *
fsl_dma_prep_interrupt(struct dma_chan *chan, unsigned long flags)
{
        struct fsl_dma_chan *fsl_chan;
        struct fsl_desc_sw *new;

        if (!chan)
                return NULL;

        fsl_chan = to_fsl_chan(chan);

        new = fsl_dma_alloc_descriptor(fsl_chan);
        if (!new) {
                dev_err(fsl_chan->dev, "No free memory for link descriptor\n");
                return NULL;
        }

        new->async_tx.cookie = -EBUSY;
        new->async_tx.flags = flags;

        /* Insert the link descriptor to the LD ring */
        list_add_tail(&new->node, &new->tx_list);

        /* Set End-of-link to the last link descriptor of new list*/
        set_ld_eol(fsl_chan, new);

        return &new->async_tx;
}

static struct dma_async_tx_descriptor *fsl_dma_prep_memcpy(
        struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src,
        size_t len, unsigned long flags)
{
        struct fsl_dma_chan *fsl_chan;
        struct fsl_desc_sw *first = NULL, *prev = NULL, *new;
        struct list_head *list;
        size_t copy;

        if (!chan)
                return NULL;

        if (!len)
                return NULL;

        fsl_chan = to_fsl_chan(chan);

        do {

                /* Allocate the link descriptor from DMA pool */
                new = fsl_dma_alloc_descriptor(fsl_chan);
                if (!new) {
                        dev_err(fsl_chan->dev,
                                        "No free memory for link descriptor\n");
                        goto fail;
                }
#ifdef FSL_DMA_LD_DEBUG
                dev_dbg(fsl_chan->dev, "new link desc alloc %p\n", new);
#endif

                copy = min(len, (size_t)FSL_DMA_BCR_MAX_CNT);

                set_desc_cnt(fsl_chan, &new->hw, copy);
                set_desc_src(fsl_chan, &new->hw, dma_src);
                set_desc_dest(fsl_chan, &new->hw, dma_dest);

                if (!first)
                        first = new;
                else
                        set_desc_next(fsl_chan, &prev->hw, new->async_tx.phys);

                new->async_tx.cookie = 0;
                async_tx_ack(&new->async_tx);

                prev = new;
                len -= copy;
                dma_src += copy;
                dma_dest += copy;

                /* Insert the link descriptor to the LD ring */
                list_add_tail(&new->node, &first->tx_list);
        } while (len);

        new->async_tx.flags = flags; /* client is in control of this ack */
        new->async_tx.cookie = -EBUSY;

        /* Set End-of-link to the last link descriptor of new list*/
        set_ld_eol(fsl_chan, new);

        return &first->async_tx;

fail:
        if (!first)
                return NULL;

        list = &first->tx_list;
        list_for_each_entry_safe_reverse(new, prev, list, node) {
                list_del(&new->node);
                dma_pool_free(fsl_chan->desc_pool, new, new->async_tx.phys);
        }

        return NULL;
}

/**
 * fsl_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
 * @chan: DMA channel
 * @sgl: scatterlist to transfer to/from
 * @sg_len: number of entries in @scatterlist
 * @direction: DMA direction
 * @flags: DMAEngine flags
 *
 * Prepare a set of descriptors for a DMA_SLAVE transaction. Following the
 * DMA_SLAVE API, this gets the device-specific information from the
 * chan->private variable.
 */
static struct dma_async_tx_descriptor *fsl_dma_prep_slave_sg(
        struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
        enum dma_data_direction direction, unsigned long flags)
{
        struct fsl_dma_chan *fsl_chan;
        struct fsl_desc_sw *first = NULL, *prev = NULL, *new = NULL;
        struct fsl_dma_slave *slave;
        struct list_head *tx_list;
        size_t copy;

        int i;
        struct scatterlist *sg;
        size_t sg_used;
        size_t hw_used;
        struct fsl_dma_hw_addr *hw;
        dma_addr_t dma_dst, dma_src;

        if (!chan)
                return NULL;

        if (!chan->private)
                return NULL;

        fsl_chan = to_fsl_chan(chan);
        slave = chan->private;

        if (list_empty(&slave->addresses))
                return NULL;

        hw = list_first_entry(&slave->addresses, struct fsl_dma_hw_addr, entry);
        hw_used = 0;

        /*
         * Build the hardware transaction to copy from the scatterlist to
         * the hardware, or from the hardware to the scatterlist
         *
         * If you are copying from the hardware to the scatterlist and it
         * takes two hardware entries to fill an entire page, then both
         * hardware entries will be coalesced into the same page
         *
         * If you are copying from the scatterlist to the hardware and a
         * single page can fill two hardware entries, then the data will
         * be read out of the page into the first hardware entry, and so on
         */
        for_each_sg(sgl, sg, sg_len, i) {
                sg_used = 0;

                /* Loop until the entire scatterlist entry is used */
                while (sg_used < sg_dma_len(sg)) {

                        /*
                         * If we've used up the current hardware address/length
                         * pair, we need to load a new one
                         *
                         * This is done in a while loop so that descriptors with
                         * length == 0 will be skipped
                         */
                        while (hw_used >= hw->length) {

                                /*
                                 * If the current hardware entry is the last
                                 * entry in the list, we're finished
                                 */
                                if (list_is_last(&hw->entry, &slave->addresses))
                                        goto finished;

                                /* Get the next hardware address/length pair */
                                hw = list_entry(hw->entry.next,
                                                struct fsl_dma_hw_addr, entry);
                                hw_used = 0;
                        }

                        /* Allocate the link descriptor from DMA pool */
                        new = fsl_dma_alloc_descriptor(fsl_chan);
                        if (!new) {
                                dev_err(fsl_chan->dev, "No free memory for "
                                                       "link descriptor\n");
                                goto fail;
                        }
#ifdef FSL_DMA_LD_DEBUG
                        dev_dbg(fsl_chan->dev, "new link desc alloc %p\n", new);
#endif

                        /*
                         * Calculate the maximum number of bytes to transfer,
                         * making sure it is less than the DMA controller limit
                         */
                        copy = min_t(size_t, sg_dma_len(sg) - sg_used,
                                             hw->length - hw_used);
                        copy = min_t(size_t, copy, FSL_DMA_BCR_MAX_CNT);

                        /*
                         * DMA_FROM_DEVICE
                         * from the hardware to the scatterlist
                         *
                         * DMA_TO_DEVICE
                         * from the scatterlist to the hardware
                         */
                        if (direction == DMA_FROM_DEVICE) {
                                dma_src = hw->address + hw_used;
                                dma_dst = sg_dma_address(sg) + sg_used;
                        } else {
                                dma_src = sg_dma_address(sg) + sg_used;
                                dma_dst = hw->address + hw_used;
                        }

                        /* Fill in the descriptor */
                        set_desc_cnt(fsl_chan, &new->hw, copy);
                        set_desc_src(fsl_chan, &new->hw, dma_src);
                        set_desc_dest(fsl_chan, &new->hw, dma_dst);

                        /*
                         * If this is not the first descriptor, chain the
                         * current descriptor after the previous descriptor
                         */
                        if (!first) {
                                first = new;
                        } else {
                                set_desc_next(fsl_chan, &prev->hw,
                                              new->async_tx.phys);
                        }

                        new->async_tx.cookie = 0;
                        async_tx_ack(&new->async_tx);

                        prev = new;
                        sg_used += copy;
                        hw_used += copy;

                        /* Insert the link descriptor into the LD ring */
                        list_add_tail(&new->node, &first->tx_list);
                }
        }

finished:

        /* All of the hardware address/length pairs had length == 0 */
        if (!first || !new)
                return NULL;

        new->async_tx.flags = flags;
        new->async_tx.cookie = -EBUSY;

        /* Set End-of-link to the last link descriptor of new list */
        set_ld_eol(fsl_chan, new);

        /* Enable extra controller features */
        if (fsl_chan->set_src_loop_size)
                fsl_chan->set_src_loop_size(fsl_chan, slave->src_loop_size);

        if (fsl_chan->set_dest_loop_size)
                fsl_chan->set_dest_loop_size(fsl_chan, slave->dst_loop_size);

        if (fsl_chan->toggle_ext_start)
                fsl_chan->toggle_ext_start(fsl_chan, slave->external_start);

        if (fsl_chan->toggle_ext_pause)
                fsl_chan->toggle_ext_pause(fsl_chan, slave->external_pause);

        if (fsl_chan->set_request_count)
                fsl_chan->set_request_count(fsl_chan, slave->request_count);

        return &first->async_tx;

fail:
        /* If first was not set, then we failed to allocate the very first
         * descriptor, and we're done */
        if (!first)
                return NULL;

        /*
         * First is set, so all of the descriptors we allocated have been added
         * to first->tx_list, INCLUDING "first" itself. Therefore we
         * must traverse the list backwards freeing each descriptor in turn
         *
         * We're re-using variables for the loop, oh well
         */
        tx_list = &first->tx_list;
        list_for_each_entry_safe_reverse(new, prev, tx_list, node) {
                list_del_init(&new->node);
                dma_pool_free(fsl_chan->desc_pool, new, new->async_tx.phys);
        }

        return NULL;
}

static void fsl_dma_device_terminate_all(struct dma_chan *chan)
{
        struct fsl_dma_chan *fsl_chan;
        struct fsl_desc_sw *desc, *tmp;
        unsigned long flags;

        if (!chan)
                return;

        fsl_chan = to_fsl_chan(chan);

        /* Halt the DMA engine */
        dma_halt(fsl_chan);

        spin_lock_irqsave(&fsl_chan->desc_lock, flags);

        /* Remove and free all of the descriptors in the LD queue */
        list_for_each_entry_safe(desc, tmp, &fsl_chan->ld_queue, node) {
                list_del(&desc->node);
                dma_pool_free(fsl_chan->desc_pool, desc, desc->async_tx.phys);
        }

        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
}

/**
 * fsl_dma_update_completed_cookie - Update the completed cookie.
 * @fsl_chan : Freescale DMA channel
 */
static void fsl_dma_update_completed_cookie(struct fsl_dma_chan *fsl_chan)
{
        struct fsl_desc_sw *cur_desc, *desc;
        dma_addr_t ld_phy;

        ld_phy = get_cdar(fsl_chan) & FSL_DMA_NLDA_MASK;

        if (ld_phy) {
                cur_desc = NULL;
                list_for_each_entry(desc, &fsl_chan->ld_queue, node)
                        if (desc->async_tx.phys == ld_phy) {
                                cur_desc = desc;
                                break;
                        }

                if (cur_desc && cur_desc->async_tx.cookie) {
                        if (dma_is_idle(fsl_chan))
                                fsl_chan->completed_cookie =
                                        cur_desc->async_tx.cookie;
                        else
                                fsl_chan->completed_cookie =
                                        cur_desc->async_tx.cookie - 1;
                }
        }
}

/**
 * fsl_chan_ld_cleanup - Clean up link descriptors
 * @fsl_chan : Freescale DMA channel
 *
 * This function clean up the ld_queue of DMA channel.
 * If 'in_intr' is set, the function will move the link descriptor to
 * the recycle list. Otherwise, free it directly.
 */
static void fsl_chan_ld_cleanup(struct fsl_dma_chan *fsl_chan)
{
        struct fsl_desc_sw *desc, *_desc;
        unsigned long flags;

        spin_lock_irqsave(&fsl_chan->desc_lock, flags);

        dev_dbg(fsl_chan->dev, "chan completed_cookie = %d\n",
                        fsl_chan->completed_cookie);
        list_for_each_entry_safe(desc, _desc, &fsl_chan->ld_queue, node) {
                dma_async_tx_callback callback;
                void *callback_param;

                if (dma_async_is_complete(desc->async_tx.cookie,
                            fsl_chan->completed_cookie, fsl_chan->common.cookie)
                                == DMA_IN_PROGRESS)
                        break;

                callback = desc->async_tx.callback;
                callback_param = desc->async_tx.callback_param;

                /* Remove from ld_queue list */
                list_del(&desc->node);

                dev_dbg(fsl_chan->dev, "link descriptor %p will be recycle.\n",
                                desc);
                dma_pool_free(fsl_chan->desc_pool, desc, desc->async_tx.phys);

                /* Run the link descriptor callback function */
                if (callback) {
                        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
                        dev_dbg(fsl_chan->dev, "link descriptor %p callback\n",
                                        desc);
                        callback(callback_param);
                        spin_lock_irqsave(&fsl_chan->desc_lock, flags);
                }
        }
        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
}

/**
 * fsl_chan_xfer_ld_queue - Transfer link descriptors in channel ld_queue.
 * @fsl_chan : Freescale DMA channel
 */
static void fsl_chan_xfer_ld_queue(struct fsl_dma_chan *fsl_chan)
{
        struct list_head *ld_node;
        dma_addr_t next_dest_addr;
        unsigned long flags;

        spin_lock_irqsave(&fsl_chan->desc_lock, flags);

        if (!dma_is_idle(fsl_chan))
                goto out_unlock;

        dma_halt(fsl_chan);

        /* If there are some link descriptors
         * not transfered in queue. We need to start it.
         */

        /* Find the first un-transfer desciptor */
        for (ld_node = fsl_chan->ld_queue.next;
                (ld_node != &fsl_chan->ld_queue)
                        && (dma_async_is_complete(
                                to_fsl_desc(ld_node)->async_tx.cookie,
                                fsl_chan->completed_cookie,
                                fsl_chan->common.cookie) == DMA_SUCCESS);
                ld_node = ld_node->next);

        if (ld_node != &fsl_chan->ld_queue) {
                /* Get the ld start address from ld_queue */
                next_dest_addr = to_fsl_desc(ld_node)->async_tx.phys;
                dev_dbg(fsl_chan->dev, "xfer LDs staring from 0x%llx\n",
                                (unsigned long long)next_dest_addr);
                set_cdar(fsl_chan, next_dest_addr);
                dma_start(fsl_chan);
        } else {
                set_cdar(fsl_chan, 0);
                set_ndar(fsl_chan, 0);
        }

out_unlock:
        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
}

/**
 * fsl_dma_memcpy_issue_pending - Issue the DMA start command
 * @fsl_chan : Freescale DMA channel
 */
static void fsl_dma_memcpy_issue_pending(struct dma_chan *chan)
{
        struct fsl_dma_chan *fsl_chan = to_fsl_chan(chan);

#ifdef FSL_DMA_LD_DEBUG
        struct fsl_desc_sw *ld;
        unsigned long flags;

        spin_lock_irqsave(&fsl_chan->desc_lock, flags);
        if (list_empty(&fsl_chan->ld_queue)) {
                spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
                return;
        }

        dev_dbg(fsl_chan->dev, "--memcpy issue--\n");
        list_for_each_entry(ld, &fsl_chan->ld_queue, node) {
                int i;
                dev_dbg(fsl_chan->dev, "Ch %d, LD %08x\n",
                                fsl_chan->id, ld->async_tx.phys);
                for (i = 0; i < 8; i++)
                        dev_dbg(fsl_chan->dev, "LD offset %d: %08x\n",
                                        i, *(((u32 *)&ld->hw) + i));
        }
        dev_dbg(fsl_chan->dev, "----------------\n");
        spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
#endif

        fsl_chan_xfer_ld_queue(fsl_chan);
}

/**
 * fsl_dma_is_complete - Determine the DMA status
 * @fsl_chan : Freescale DMA channel
 */
static enum dma_status fsl_dma_is_complete(struct dma_chan *chan,
                                        dma_cookie_t cookie,
                                        dma_cookie_t *done,
                                        dma_cookie_t *used)
{
        struct fsl_dma_chan *fsl_chan = to_fsl_chan(chan);
        dma_cookie_t last_used;
        dma_cookie_t last_complete;

        fsl_chan_ld_cleanup(fsl_chan);

        last_used = chan->cookie;
        last_complete = fsl_chan->completed_cookie;

        if (done)
                *done = last_complete;

        if (used)
                *used = last_used;

        return dma_async_is_complete(cookie, last_complete, last_used);
}

static irqreturn_t fsl_dma_chan_do_interrupt(int irq, void *data)
{
        struct fsl_dma_chan *fsl_chan = (struct fsl_dma_chan *)data;
        u32 stat;
        int update_cookie = 0;
        int xfer_ld_q = 0;

        stat = get_sr(fsl_chan);
        dev_dbg(fsl_chan->dev, "event: channel %d, stat = 0x%x\n",
                                                fsl_chan->id, stat);
        set_sr(fsl_chan, stat);         /* Clear the event register */

        stat &= ~(FSL_DMA_SR_CB | FSL_DMA_SR_CH);
        if (!stat)
                return IRQ_NONE;

        if (stat & FSL_DMA_SR_TE)
                dev_err(fsl_chan->dev, "Transfer Error!\n");

        /* Programming Error
         * The DMA_INTERRUPT async_tx is a NULL transfer, which will
         * triger a PE interrupt.
         */
        if (stat & FSL_DMA_SR_PE) {
                dev_dbg(fsl_chan->dev, "event: Programming Error INT\n");
                if (get_bcr(fsl_chan) == 0) {
                        /* BCR register is 0, this is a DMA_INTERRUPT async_tx.
                         * Now, update the completed cookie, and continue the
                         * next uncompleted transfer.
                         */
                        update_cookie = 1;
                        xfer_ld_q = 1;
                }
                stat &= ~FSL_DMA_SR_PE;
        }

        /* If the link descriptor segment transfer finishes,
         * we will recycle the used descriptor.
         */
        if (stat & FSL_DMA_SR_EOSI) {
                dev_dbg(fsl_chan->dev, "event: End-of-segments INT\n");
                dev_dbg(fsl_chan->dev, "event: clndar 0x%llx, nlndar 0x%llx\n",
                        (unsigned long long)get_cdar(fsl_chan),
                        (unsigned long long)get_ndar(fsl_chan));
                stat &= ~FSL_DMA_SR_EOSI;
                update_cookie = 1;
        }

        /* For MPC8349, EOCDI event need to update cookie
         * and start the next transfer if it exist.
         */
        if (stat & FSL_DMA_SR_EOCDI) {
                dev_dbg(fsl_chan->dev, "event: End-of-Chain link INT\n");
                stat &= ~FSL_DMA_SR_EOCDI;
                update_cookie = 1;
                xfer_ld_q = 1;
        }

        /* If it current transfer is the end-of-transfer,
         * we should clear the Channel Start bit for
         * prepare next transfer.
         */
        if (stat & FSL_DMA_SR_EOLNI) {
                dev_dbg(fsl_chan->dev, "event: End-of-link INT\n");
                stat &= ~FSL_DMA_SR_EOLNI;
                xfer_ld_q = 1;
        }

        if (update_cookie)
                fsl_dma_update_completed_cookie(fsl_chan);
        if (xfer_ld_q)
                fsl_chan_xfer_ld_queue(fsl_chan);
        if (stat)
                dev_dbg(fsl_chan->dev, "event: unhandled sr 0x%02x\n",
                                        stat);

        dev_dbg(fsl_chan->dev, "event: Exit\n");
        tasklet_schedule(&fsl_chan->tasklet);
        return IRQ_HANDLED;
}

static irqreturn_t fsl_dma_do_interrupt(int irq, void *data)
{
        struct fsl_dma_device *fdev = (struct fsl_dma_device *)data;
        u32 gsr;
        int ch_nr;

        gsr = (fdev->feature & FSL_DMA_BIG_ENDIAN) ? in_be32(fdev->reg_base)
                        : in_le32(fdev->reg_base);
        ch_nr = (32 - ffs(gsr)) / 8;

        return fdev->chan[ch_nr] ? fsl_dma_chan_do_interrupt(irq,
                        fdev->chan[ch_nr]) : IRQ_NONE;
}

static void dma_do_tasklet(unsigned long data)
{
        struct fsl_dma_chan *fsl_chan = (struct fsl_dma_chan *)data;
        fsl_chan_ld_cleanup(fsl_chan);
}

static int __devinit fsl_dma_chan_probe(struct fsl_dma_device *fdev,
        struct device_node *node, u32 feature, const char *compatible)
{
        struct fsl_dma_chan *new_fsl_chan;
        int err;

        /* alloc channel */
        new_fsl_chan = kzalloc(sizeof(struct fsl_dma_chan), GFP_KERNEL);
        if (!new_fsl_chan) {
                dev_err(fdev->dev, "No free memory for allocating "
                                "dma channels!\n");
                return -ENOMEM;
        }

        /* get dma channel register base */
        err = of_address_to_resource(node, 0, &new_fsl_chan->reg);
        if (err) {
                dev_err(fdev->dev, "Can't get %s property 'reg'\n",
                                node->full_name);
                goto err_no_reg;
        }

        new_fsl_chan->feature = feature;

        if (!fdev->feature)
                fdev->feature = new_fsl_chan->feature;

        /* If the DMA device's feature is different than its channels',
         * report the bug.
         */
        WARN_ON(fdev->feature != new_fsl_chan->feature);

        new_fsl_chan->dev = fdev->dev;
        new_fsl_chan->reg_base = ioremap(new_fsl_chan->reg.start,
                        new_fsl_chan->reg.end - new_fsl_chan->reg.start + 1);

        new_fsl_chan->id = ((new_fsl_chan->reg.start - 0x100) & 0xfff) >> 7;
        if (new_fsl_chan->id >= FSL_DMA_MAX_CHANS_PER_DEVICE) {
                dev_err(fdev->dev, "There is no %d channel!\n",
                                new_fsl_chan->id);
                err = -EINVAL;
                goto err_no_chan;
        }
        fdev->chan[new_fsl_chan->id] = new_fsl_chan;
        tasklet_init(&new_fsl_chan->tasklet, dma_do_tasklet,
                        (unsigned long)new_fsl_chan);

        /* Init the channel */
        dma_init(new_fsl_chan);

        /* Clear cdar registers */
        set_cdar(new_fsl_chan, 0);

        switch (new_fsl_chan->feature & FSL_DMA_IP_MASK) {
        case FSL_DMA_IP_85XX:
                new_fsl_chan->toggle_ext_pause = fsl_chan_toggle_ext_pause;
        case FSL_DMA_IP_83XX:
                new_fsl_chan->toggle_ext_start = fsl_chan_toggle_ext_start;
                new_fsl_chan->set_src_loop_size = fsl_chan_set_src_loop_size;
                new_fsl_chan->set_dest_loop_size = fsl_chan_set_dest_loop_size;
                new_fsl_chan->set_request_count = fsl_chan_set_request_count;
        }

        spin_lock_init(&new_fsl_chan->desc_lock);
        INIT_LIST_HEAD(&new_fsl_chan->ld_queue);

        new_fsl_chan->common.device = &fdev->common;

        /* Add the channel to DMA device channel list */
        list_add_tail(&new_fsl_chan->common.device_node,
                        &fdev->common.channels);
        fdev->common.chancnt++;

        new_fsl_chan->irq = irq_of_parse_and_map(node, 0);
        if (new_fsl_chan->irq != NO_IRQ) {
                err = request_irq(new_fsl_chan->irq,
                                        &fsl_dma_chan_do_interrupt, IRQF_SHARED,
                                        "fsldma-channel", new_fsl_chan);
                if (err) {
                        dev_err(fdev->dev, "DMA channel %s request_irq error "
                                "with return %d\n", node->full_name, err);
                        goto err_no_irq;
                }
        }

        dev_info(fdev->dev, "#%d (%s), irq %d\n", new_fsl_chan->id,
                 compatible,
                 new_fsl_chan->irq != NO_IRQ ? new_fsl_chan->irq : fdev->irq);

        return 0;

err_no_irq:
        list_del(&new_fsl_chan->common.device_node);
err_no_chan:
        iounmap(new_fsl_chan->reg_base);
err_no_reg:
        kfree(new_fsl_chan);
        return err;
}

static void fsl_dma_chan_remove(struct fsl_dma_chan *fchan)
{
        if (fchan->irq != NO_IRQ)
                free_irq(fchan->irq, fchan);
        list_del(&fchan->common.device_node);
        iounmap(fchan->reg_base);
        kfree(fchan);
}

static int __devinit of_fsl_dma_probe(struct of_device *dev,
                        const struct of_device_id *match)
{
        int err;
        struct fsl_dma_device *fdev;
        struct device_node *child;

        fdev = kzalloc(sizeof(struct fsl_dma_device), GFP_KERNEL);
        if (!fdev) {
                dev_err(&dev->dev, "No enough memory for 'priv'\n");
                return -ENOMEM;
        }
        fdev->dev = &dev->dev;
        INIT_LIST_HEAD(&fdev->common.channels);

        /* get DMA controller register base */
        err = of_address_to_resource(dev->node, 0, &fdev->reg);
        if (err) {
                dev_err(&dev->dev, "Can't get %s property 'reg'\n",
                                dev->node->full_name);
                goto err_no_reg;
        }

        dev_info(&dev->dev, "Probe the Freescale DMA driver for %s "
                        "controller at 0x%llx...\n",
                        match->compatible, (unsigned long long)fdev->reg.start);
        fdev->reg_base = ioremap(fdev->reg.start, fdev->reg.end
                                                - fdev->reg.start + 1);

        dma_cap_set(DMA_MEMCPY, fdev->common.cap_mask);
        dma_cap_set(DMA_INTERRUPT, fdev->common.cap_mask);
        dma_cap_set(DMA_SLAVE, fdev->common.cap_mask);
        fdev->common.device_alloc_chan_resources = fsl_dma_alloc_chan_resources;
        fdev->common.device_free_chan_resources = fsl_dma_free_chan_resources;
        fdev->common.device_prep_dma_interrupt = fsl_dma_prep_interrupt;
        fdev->common.device_prep_dma_memcpy = fsl_dma_prep_memcpy;
        fdev->common.device_is_tx_complete = fsl_dma_is_complete;
        fdev->common.device_issue_pending = fsl_dma_memcpy_issue_pending;
        fdev->common.device_prep_slave_sg = fsl_dma_prep_slave_sg;
        fdev->common.device_terminate_all = fsl_dma_device_terminate_all;
        fdev->common.dev = &dev->dev;

        fdev->irq = irq_of_parse_and_map(dev->node, 0);
        if (fdev->irq != NO_IRQ) {
                err = request_irq(fdev->irq, &fsl_dma_do_interrupt, IRQF_SHARED,
                                        "fsldma-device", fdev);
                if (err) {
                        dev_err(&dev->dev, "DMA device request_irq error "
                                "with return %d\n", err);
                        goto err;
                }
        }

        dev_set_drvdata(&(dev->dev), fdev);

        /* We cannot use of_platform_bus_probe() because there is no
         * of_platform_bus_remove.  Instead, we manually instantiate every DMA
         * channel object.
         */
        for_each_child_of_node(dev->node, child) {
                if (of_device_is_compatible(child, "fsl,eloplus-dma-channel"))
                        fsl_dma_chan_probe(fdev, child,
                                FSL_DMA_IP_85XX | FSL_DMA_BIG_ENDIAN,
                                "fsl,eloplus-dma-channel");
                if (of_device_is_compatible(child, "fsl,elo-dma-channel"))
                        fsl_dma_chan_probe(fdev, child,
                                FSL_DMA_IP_83XX | FSL_DMA_LITTLE_ENDIAN,
                                "fsl,elo-dma-channel");
        }

        dma_async_device_register(&fdev->common);
        return 0;

err:
        iounmap(fdev->reg_base);
err_no_reg:
        kfree(fdev);
        return err;
}

static int of_fsl_dma_remove(struct of_device *of_dev)
{
        struct fsl_dma_device *fdev;
        unsigned int i;

        fdev = dev_get_drvdata(&of_dev->dev);

        dma_async_device_unregister(&fdev->common);

        for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++)
                if (fdev->chan[i])
                        fsl_dma_chan_remove(fdev->chan[i]);

        if (fdev->irq != NO_IRQ)
                free_irq(fdev->irq, fdev);

        iounmap(fdev->reg_base);

        kfree(fdev);
        dev_set_drvdata(&of_dev->dev, NULL);

        return 0;
}

static struct of_device_id of_fsl_dma_ids[] = {
        { .compatible = "fsl,eloplus-dma", },
        { .compatible = "fsl,elo-dma", },
        {}
};

static struct of_platform_driver of_fsl_dma_driver = {
        .name = "fsl-elo-dma",
        .match_table = of_fsl_dma_ids,
        .probe = of_fsl_dma_probe,
        .remove = of_fsl_dma_remove,
};

static __init int of_fsl_dma_init(void)
{
        int ret;

        pr_info("Freescale Elo / Elo Plus DMA driver\n");

        ret = of_register_platform_driver(&of_fsl_dma_driver);
        if (ret)
                pr_err("fsldma: failed to register platform driver\n");

        return ret;
}

static void __exit of_fsl_dma_exit(void)
{
        of_unregister_platform_driver(&of_fsl_dma_driver);
}

subsys_initcall(of_fsl_dma_init);
module_exit(of_fsl_dma_exit);

MODULE_DESCRIPTION("Freescale Elo / Elo Plus DMA driver");
MODULE_LICENSE("GPL");