/*
 * TUSB6010 USB 2.0 OTG Dual Role controller OMAP DMA interface
 *
 * Copyright (C) 2006 Nokia Corporation
 * Tony Lindgren <tony@atomide.com>
 *
 * 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/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/usb.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <plat/dma.h>

#include "musb_core.h"
#include "tusb6010.h"

#define to_chdat(c)             ((struct tusb_omap_dma_ch *)(c)->private_data)

#define MAX_DMAREQ              5       /* REVISIT: Really 6, but req5 not OK */

struct tusb_omap_dma_ch {
        struct musb             *musb;
        void __iomem            *tbase;
        unsigned long           phys_offset;
        int                     epnum;
        u8                      tx;
        struct musb_hw_ep       *hw_ep;

        int                     ch;
        s8                      dmareq;
        s8                      sync_dev;

        struct tusb_omap_dma    *tusb_dma;

        dma_addr_t              dma_addr;

        u32                     len;
        u16                     packet_sz;
        u16                     transfer_packet_sz;
        u32                     transfer_len;
        u32                     completed_len;
};

struct tusb_omap_dma {
        struct dma_controller           controller;
        struct musb                     *musb;
        void __iomem                    *tbase;

        int                             ch;
        s8                              dmareq;
        s8                              sync_dev;
        unsigned                        multichannel:1;
};

static int tusb_omap_dma_start(struct dma_controller *c)
{
        struct tusb_omap_dma    *tusb_dma;

        tusb_dma = container_of(c, struct tusb_omap_dma, controller);

        /* dev_dbg(musb->controller, "ep%i ch: %i\n", chdat->epnum, chdat->ch); */

        return 0;
}

static int tusb_omap_dma_stop(struct dma_controller *c)
{
        struct tusb_omap_dma    *tusb_dma;

        tusb_dma = container_of(c, struct tusb_omap_dma, controller);

        /* dev_dbg(musb->controller, "ep%i ch: %i\n", chdat->epnum, chdat->ch); */

        return 0;
}

/*
 * Allocate dmareq0 to the current channel unless it's already taken
 */
static inline int tusb_omap_use_shared_dmareq(struct tusb_omap_dma_ch *chdat)
{
        u32             reg = musb_readl(chdat->tbase, TUSB_DMA_EP_MAP);

        if (reg != 0) {
                dev_dbg(chdat->musb->controller, "ep%i dmareq0 is busy for ep%i\n",
                        chdat->epnum, reg & 0xf);
                return -EAGAIN;
        }

        if (chdat->tx)
                reg = (1 << 4) | chdat->epnum;
        else
                reg = chdat->epnum;

        musb_writel(chdat->tbase, TUSB_DMA_EP_MAP, reg);

        return 0;
}

static inline void tusb_omap_free_shared_dmareq(struct tusb_omap_dma_ch *chdat)
{
        u32             reg = musb_readl(chdat->tbase, TUSB_DMA_EP_MAP);

        if ((reg & 0xf) != chdat->epnum) {
                printk(KERN_ERR "ep%i trying to release dmareq0 for ep%i\n",
                        chdat->epnum, reg & 0xf);
                return;
        }
        musb_writel(chdat->tbase, TUSB_DMA_EP_MAP, 0);
}

/*
 * See also musb_dma_completion in plat_uds.c and musb_g_[tx|rx]() in
 * musb_gadget.c.
 */
static void tusb_omap_dma_cb(int lch, u16 ch_status, void *data)
{
        struct dma_channel      *channel = (struct dma_channel *)data;
        struct tusb_omap_dma_ch *chdat = to_chdat(channel);
        struct tusb_omap_dma    *tusb_dma = chdat->tusb_dma;
        struct musb             *musb = chdat->musb;
        struct device           *dev = musb->controller;
        struct musb_hw_ep       *hw_ep = chdat->hw_ep;
        void __iomem            *ep_conf = hw_ep->conf;
        void __iomem            *mbase = musb->mregs;
        unsigned long           remaining, flags, pio;
        int                     ch;

        spin_lock_irqsave(&musb->lock, flags);

        if (tusb_dma->multichannel)
                ch = chdat->ch;
        else
                ch = tusb_dma->ch;

        if (ch_status != OMAP_DMA_BLOCK_IRQ)
                printk(KERN_ERR "TUSB DMA error status: %i\n", ch_status);

        dev_dbg(musb->controller, "ep%i %s dma callback ch: %i status: %x\n",
                chdat->epnum, chdat->tx ? "tx" : "rx",
                ch, ch_status);

        if (chdat->tx)
                remaining = musb_readl(ep_conf, TUSB_EP_TX_OFFSET);
        else
                remaining = musb_readl(ep_conf, TUSB_EP_RX_OFFSET);

        remaining = TUSB_EP_CONFIG_XFR_SIZE(remaining);

        /* HW issue #10: XFR_SIZE may get corrupt on DMA (both async & sync) */
        if (unlikely(remaining > chdat->transfer_len)) {
                dev_dbg(musb->controller, "Corrupt %s dma ch%i XFR_SIZE: 0x%08lx\n",
                        chdat->tx ? "tx" : "rx", chdat->ch,
                        remaining);
                remaining = 0;
        }

        channel->actual_len = chdat->transfer_len - remaining;
        pio = chdat->len - channel->actual_len;

        dev_dbg(musb->controller, "DMA remaining %lu/%u\n", remaining, chdat->transfer_len);

        /* Transfer remaining 1 - 31 bytes */
        if (pio > 0 && pio < 32) {
                u8      *buf;

                dev_dbg(musb->controller, "Using PIO for remaining %lu bytes\n", pio);
                buf = phys_to_virt((u32)chdat->dma_addr) + chdat->transfer_len;
                if (chdat->tx) {
                        dma_unmap_single(dev, chdat->dma_addr,
                                                chdat->transfer_len,
                                                DMA_TO_DEVICE);
                        musb_write_fifo(hw_ep, pio, buf);
                } else {
                        dma_unmap_single(dev, chdat->dma_addr,
                                                chdat->transfer_len,
                                                DMA_FROM_DEVICE);
                        musb_read_fifo(hw_ep, pio, buf);
                }
                channel->actual_len += pio;
        }

        if (!tusb_dma->multichannel)
                tusb_omap_free_shared_dmareq(chdat);

        channel->status = MUSB_DMA_STATUS_FREE;

        /* Handle only RX callbacks here. TX callbacks must be handled based
         * on the TUSB DMA status interrupt.
         * REVISIT: Use both TUSB DMA status interrupt and OMAP DMA callback
         * interrupt for RX and TX.
         */
        if (!chdat->tx)
                musb_dma_completion(musb, chdat->epnum, chdat->tx);

        /* We must terminate short tx transfers manually by setting TXPKTRDY.
         * REVISIT: This same problem may occur with other MUSB dma as well.
         * Easy to test with g_ether by pinging the MUSB board with ping -s54.
         */
        if ((chdat->transfer_len < chdat->packet_sz)
                        || (chdat->transfer_len % chdat->packet_sz != 0)) {
                u16     csr;

                if (chdat->tx) {
                        dev_dbg(musb->controller, "terminating short tx packet\n");
                        musb_ep_select(mbase, chdat->epnum);
                        csr = musb_readw(hw_ep->regs, MUSB_TXCSR);
                        csr |= MUSB_TXCSR_MODE | MUSB_TXCSR_TXPKTRDY
                                | MUSB_TXCSR_P_WZC_BITS;
                        musb_writew(hw_ep->regs, MUSB_TXCSR, csr);
                }
        }

        spin_unlock_irqrestore(&musb->lock, flags);
}

static int tusb_omap_dma_program(struct dma_channel *channel, u16 packet_sz,
                                u8 rndis_mode, dma_addr_t dma_addr, u32 len)
{
        struct tusb_omap_dma_ch         *chdat = to_chdat(channel);
        struct tusb_omap_dma            *tusb_dma = chdat->tusb_dma;
        struct musb                     *musb = chdat->musb;
        struct device                   *dev = musb->controller;
        struct musb_hw_ep               *hw_ep = chdat->hw_ep;
        void __iomem                    *mbase = musb->mregs;
        void __iomem                    *ep_conf = hw_ep->conf;
        dma_addr_t                      fifo = hw_ep->fifo_sync;
        struct omap_dma_channel_params  dma_params;
        u32                             dma_remaining;
        int                             src_burst, dst_burst;
        u16                             csr;
        int                             ch;
        s8                              dmareq;
        s8                              sync_dev;

        if (unlikely(dma_addr & 0x1) || (len < 32) || (len > packet_sz))
                return false;

        /*
         * HW issue #10: Async dma will eventually corrupt the XFR_SIZE
         * register which will cause missed DMA interrupt. We could try to
         * use a timer for the callback, but it is unsafe as the XFR_SIZE
         * register is corrupt, and we won't know if the DMA worked.
         */
        if (dma_addr & 0x2)
                return false;

        /*
         * Because of HW issue #10, it seems like mixing sync DMA and async
         * PIO access can confuse the DMA. Make sure XFR_SIZE is reset before
         * using the channel for DMA.
         */
        if (chdat->tx)
                dma_remaining = musb_readl(ep_conf, TUSB_EP_TX_OFFSET);
        else
                dma_remaining = musb_readl(ep_conf, TUSB_EP_RX_OFFSET);

        dma_remaining = TUSB_EP_CONFIG_XFR_SIZE(dma_remaining);
        if (dma_remaining) {
                dev_dbg(musb->controller, "Busy %s dma ch%i, not using: %08x\n",
                        chdat->tx ? "tx" : "rx", chdat->ch,
                        dma_remaining);
                return false;
        }

        chdat->transfer_len = len & ~0x1f;

        if (len < packet_sz)
                chdat->transfer_packet_sz = chdat->transfer_len;
        else
                chdat->transfer_packet_sz = packet_sz;

        if (tusb_dma->multichannel) {
                ch = chdat->ch;
                dmareq = chdat->dmareq;
                sync_dev = chdat->sync_dev;
        } else {
                if (tusb_omap_use_shared_dmareq(chdat) != 0) {
                        dev_dbg(musb->controller, "could not get dma for ep%i\n", chdat->epnum);
                        return false;
                }
                if (tusb_dma->ch < 0) {
                        /* REVISIT: This should get blocked earlier, happens
                         * with MSC ErrorRecoveryTest
                         */
                        WARN_ON(1);
                        return false;
                }

                ch = tusb_dma->ch;
                dmareq = tusb_dma->dmareq;
                sync_dev = tusb_dma->sync_dev;
                omap_set_dma_callback(ch, tusb_omap_dma_cb, channel);
        }

        chdat->packet_sz = packet_sz;
        chdat->len = len;
        channel->actual_len = 0;
        chdat->dma_addr = dma_addr;
        channel->status = MUSB_DMA_STATUS_BUSY;

        /* Since we're recycling dma areas, we need to clean or invalidate */
        if (chdat->tx)
                dma_map_single(dev, phys_to_virt(dma_addr), len,
                                DMA_TO_DEVICE);
        else
                dma_map_single(dev, phys_to_virt(dma_addr), len,
                                DMA_FROM_DEVICE);

        /* Use 16-bit transfer if dma_addr is not 32-bit aligned */
        if ((dma_addr & 0x3) == 0) {
                dma_params.data_type = OMAP_DMA_DATA_TYPE_S32;
                dma_params.elem_count = 8;              /* Elements in frame */
        } else {
                dma_params.data_type = OMAP_DMA_DATA_TYPE_S16;
                dma_params.elem_count = 16;             /* Elements in frame */
                fifo = hw_ep->fifo_async;
        }

        dma_params.frame_count  = chdat->transfer_len / 32; /* Burst sz frame */

        dev_dbg(musb->controller, "ep%i %s dma ch%i dma: %08x len: %u(%u) packet_sz: %i(%i)\n",
                chdat->epnum, chdat->tx ? "tx" : "rx",
                ch, dma_addr, chdat->transfer_len, len,
                chdat->transfer_packet_sz, packet_sz);

        /*
         * Prepare omap DMA for transfer
         */
        if (chdat->tx) {
                dma_params.src_amode    = OMAP_DMA_AMODE_POST_INC;
                dma_params.src_start    = (unsigned long)dma_addr;
                dma_params.src_ei       = 0;
                dma_params.src_fi       = 0;

                dma_params.dst_amode    = OMAP_DMA_AMODE_DOUBLE_IDX;
                dma_params.dst_start    = (unsigned long)fifo;
                dma_params.dst_ei       = 1;
                dma_params.dst_fi       = -31;  /* Loop 32 byte window */

                dma_params.trigger      = sync_dev;
                dma_params.sync_mode    = OMAP_DMA_SYNC_FRAME;
                dma_params.src_or_dst_synch     = 0;    /* Dest sync */

                src_burst = OMAP_DMA_DATA_BURST_16;     /* 16x32 read */
                dst_burst = OMAP_DMA_DATA_BURST_8;      /* 8x32 write */
        } else {
                dma_params.src_amode    = OMAP_DMA_AMODE_DOUBLE_IDX;
                dma_params.src_start    = (unsigned long)fifo;
                dma_params.src_ei       = 1;
                dma_params.src_fi       = -31;  /* Loop 32 byte window */

                dma_params.dst_amode    = OMAP_DMA_AMODE_POST_INC;
                dma_params.dst_start    = (unsigned long)dma_addr;
                dma_params.dst_ei       = 0;
                dma_params.dst_fi       = 0;

                dma_params.trigger      = sync_dev;
                dma_params.sync_mode    = OMAP_DMA_SYNC_FRAME;
                dma_params.src_or_dst_synch     = 1;    /* Source sync */

                src_burst = OMAP_DMA_DATA_BURST_8;      /* 8x32 read */
                dst_burst = OMAP_DMA_DATA_BURST_16;     /* 16x32 write */
        }

        dev_dbg(musb->controller, "ep%i %s using %i-bit %s dma from 0x%08lx to 0x%08lx\n",
                chdat->epnum, chdat->tx ? "tx" : "rx",
                (dma_params.data_type == OMAP_DMA_DATA_TYPE_S32) ? 32 : 16,
                ((dma_addr & 0x3) == 0) ? "sync" : "async",
                dma_params.src_start, dma_params.dst_start);

        omap_set_dma_params(ch, &dma_params);
        omap_set_dma_src_burst_mode(ch, src_burst);
        omap_set_dma_dest_burst_mode(ch, dst_burst);
        omap_set_dma_write_mode(ch, OMAP_DMA_WRITE_LAST_NON_POSTED);

        /*
         * Prepare MUSB for DMA transfer
         */
        if (chdat->tx) {
                musb_ep_select(mbase, chdat->epnum);
                csr = musb_readw(hw_ep->regs, MUSB_TXCSR);
                csr |= (MUSB_TXCSR_AUTOSET | MUSB_TXCSR_DMAENAB
                        | MUSB_TXCSR_DMAMODE | MUSB_TXCSR_MODE);
                csr &= ~MUSB_TXCSR_P_UNDERRUN;
                musb_writew(hw_ep->regs, MUSB_TXCSR, csr);
        } else {
                musb_ep_select(mbase, chdat->epnum);
                csr = musb_readw(hw_ep->regs, MUSB_RXCSR);
                csr |= MUSB_RXCSR_DMAENAB;
                csr &= ~(MUSB_RXCSR_AUTOCLEAR | MUSB_RXCSR_DMAMODE);
                musb_writew(hw_ep->regs, MUSB_RXCSR,
                        csr | MUSB_RXCSR_P_WZC_BITS);
        }

        /*
         * Start DMA transfer
         */
        omap_start_dma(ch);

        if (chdat->tx) {
                /* Send transfer_packet_sz packets at a time */
                musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET,
                        chdat->transfer_packet_sz);

                musb_writel(ep_conf, TUSB_EP_TX_OFFSET,
                        TUSB_EP_CONFIG_XFR_SIZE(chdat->transfer_len));
        } else {
                /* Receive transfer_packet_sz packets at a time */
                musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET,
                        chdat->transfer_packet_sz << 16);

                musb_writel(ep_conf, TUSB_EP_RX_OFFSET,
                        TUSB_EP_CONFIG_XFR_SIZE(chdat->transfer_len));
        }

        return true;
}

static int tusb_omap_dma_abort(struct dma_channel *channel)
{
        struct tusb_omap_dma_ch *chdat = to_chdat(channel);
        struct tusb_omap_dma    *tusb_dma = chdat->tusb_dma;

        if (!tusb_dma->multichannel) {
                if (tusb_dma->ch >= 0) {
                        omap_stop_dma(tusb_dma->ch);
                        omap_free_dma(tusb_dma->ch);
                        tusb_dma->ch = -1;
                }

                tusb_dma->dmareq = -1;
                tusb_dma->sync_dev = -1;
        }

        channel->status = MUSB_DMA_STATUS_FREE;

        return 0;
}

static inline int tusb_omap_dma_allocate_dmareq(struct tusb_omap_dma_ch *chdat)
{
        u32             reg = musb_readl(chdat->tbase, TUSB_DMA_EP_MAP);
        int             i, dmareq_nr = -1;

        const int sync_dev[6] = {
                OMAP24XX_DMA_EXT_DMAREQ0,
                OMAP24XX_DMA_EXT_DMAREQ1,
                OMAP242X_DMA_EXT_DMAREQ2,
                OMAP242X_DMA_EXT_DMAREQ3,
                OMAP242X_DMA_EXT_DMAREQ4,
                OMAP242X_DMA_EXT_DMAREQ5,
        };

        for (i = 0; i < MAX_DMAREQ; i++) {
                int cur = (reg & (0xf << (i * 5))) >> (i * 5);
                if (cur == 0) {
                        dmareq_nr = i;
                        break;
                }
        }

        if (dmareq_nr == -1)
                return -EAGAIN;

        reg |= (chdat->epnum << (dmareq_nr * 5));
        if (chdat->tx)
                reg |= ((1 << 4) << (dmareq_nr * 5));
        musb_writel(chdat->tbase, TUSB_DMA_EP_MAP, reg);

        chdat->dmareq = dmareq_nr;
        chdat->sync_dev = sync_dev[chdat->dmareq];

        return 0;
}

static inline void tusb_omap_dma_free_dmareq(struct tusb_omap_dma_ch *chdat)
{
        u32 reg;

        if (!chdat || chdat->dmareq < 0)
                return;

        reg = musb_readl(chdat->tbase, TUSB_DMA_EP_MAP);
        reg &= ~(0x1f << (chdat->dmareq * 5));
        musb_writel(chdat->tbase, TUSB_DMA_EP_MAP, reg);

        chdat->dmareq = -1;
        chdat->sync_dev = -1;
}

static struct dma_channel *dma_channel_pool[MAX_DMAREQ];

static struct dma_channel *
tusb_omap_dma_allocate(struct dma_controller *c,
                struct musb_hw_ep *hw_ep,
                u8 tx)
{
        int ret, i;
        const char              *dev_name;
        struct tusb_omap_dma    *tusb_dma;
        struct musb             *musb;
        void __iomem            *tbase;
        struct dma_channel      *channel = NULL;
        struct tusb_omap_dma_ch *chdat = NULL;
        u32                     reg;

        tusb_dma = container_of(c, struct tusb_omap_dma, controller);
        musb = tusb_dma->musb;
        tbase = musb->ctrl_base;

        reg = musb_readl(tbase, TUSB_DMA_INT_MASK);
        if (tx)
                reg &= ~(1 << hw_ep->epnum);
        else
                reg &= ~(1 << (hw_ep->epnum + 15));
        musb_writel(tbase, TUSB_DMA_INT_MASK, reg);

        /* REVISIT: Why does dmareq5 not work? */
        if (hw_ep->epnum == 0) {
                dev_dbg(musb->controller, "Not allowing DMA for ep0 %s\n", tx ? "tx" : "rx");
                return NULL;
        }

        for (i = 0; i < MAX_DMAREQ; i++) {
                struct dma_channel *ch = dma_channel_pool[i];
                if (ch->status == MUSB_DMA_STATUS_UNKNOWN) {
                        ch->status = MUSB_DMA_STATUS_FREE;
                        channel = ch;
                        chdat = ch->private_data;
                        break;
                }
        }

        if (!channel)
                return NULL;

        if (tx) {
                chdat->tx = 1;
                dev_name = "TUSB transmit";
        } else {
                chdat->tx = 0;
                dev_name = "TUSB receive";
        }

        chdat->musb = tusb_dma->musb;
        chdat->tbase = tusb_dma->tbase;
        chdat->hw_ep = hw_ep;
        chdat->epnum = hw_ep->epnum;
        chdat->dmareq = -1;
        chdat->completed_len = 0;
        chdat->tusb_dma = tusb_dma;

        channel->max_len = 0x7fffffff;
        channel->desired_mode = 0;
        channel->actual_len = 0;

        if (tusb_dma->multichannel) {
                ret = tusb_omap_dma_allocate_dmareq(chdat);
                if (ret != 0)
                        goto free_dmareq;

                ret = omap_request_dma(chdat->sync_dev, dev_name,
                                tusb_omap_dma_cb, channel, &chdat->ch);
                if (ret != 0)
                        goto free_dmareq;
        } else if (tusb_dma->ch == -1) {
                tusb_dma->dmareq = 0;
                tusb_dma->sync_dev = OMAP24XX_DMA_EXT_DMAREQ0;

                /* Callback data gets set later in the shared dmareq case */
                ret = omap_request_dma(tusb_dma->sync_dev, "TUSB shared",
                                tusb_omap_dma_cb, NULL, &tusb_dma->ch);
                if (ret != 0)
                        goto free_dmareq;

                chdat->dmareq = -1;
                chdat->ch = -1;
        }

        dev_dbg(musb->controller, "ep%i %s dma: %s dma%i dmareq%i sync%i\n",
                chdat->epnum,
                chdat->tx ? "tx" : "rx",
                chdat->ch >= 0 ? "dedicated" : "shared",
                chdat->ch >= 0 ? chdat->ch : tusb_dma->ch,
                chdat->dmareq >= 0 ? chdat->dmareq : tusb_dma->dmareq,
                chdat->sync_dev >= 0 ? chdat->sync_dev : tusb_dma->sync_dev);

        return channel;

free_dmareq:
        tusb_omap_dma_free_dmareq(chdat);

        dev_dbg(musb->controller, "ep%i: Could not get a DMA channel\n", chdat->epnum);
        channel->status = MUSB_DMA_STATUS_UNKNOWN;

        return NULL;
}

static void tusb_omap_dma_release(struct dma_channel *channel)
{
        struct tusb_omap_dma_ch *chdat = to_chdat(channel);
        struct musb             *musb = chdat->musb;
        void __iomem            *tbase = musb->ctrl_base;
        u32                     reg;

        dev_dbg(musb->controller, "ep%i ch%i\n", chdat->epnum, chdat->ch);

        reg = musb_readl(tbase, TUSB_DMA_INT_MASK);
        if (chdat->tx)
                reg |= (1 << chdat->epnum);
        else
                reg |= (1 << (chdat->epnum + 15));
        musb_writel(tbase, TUSB_DMA_INT_MASK, reg);

        reg = musb_readl(tbase, TUSB_DMA_INT_CLEAR);
        if (chdat->tx)
                reg |= (1 << chdat->epnum);
        else
                reg |= (1 << (chdat->epnum + 15));
        musb_writel(tbase, TUSB_DMA_INT_CLEAR, reg);

        channel->status = MUSB_DMA_STATUS_UNKNOWN;

        if (chdat->ch >= 0) {
                omap_stop_dma(chdat->ch);
                omap_free_dma(chdat->ch);
                chdat->ch = -1;
        }

        if (chdat->dmareq >= 0)
                tusb_omap_dma_free_dmareq(chdat);

        channel = NULL;
}

void dma_controller_destroy(struct dma_controller *c)
{
        struct tusb_omap_dma    *tusb_dma;
        int                     i;

        tusb_dma = container_of(c, struct tusb_omap_dma, controller);
        for (i = 0; i < MAX_DMAREQ; i++) {
                struct dma_channel *ch = dma_channel_pool[i];
                if (ch) {
                        kfree(ch->private_data);
                        kfree(ch);
                }
        }

        if (tusb_dma && !tusb_dma->multichannel && tusb_dma->ch >= 0)
                omap_free_dma(tusb_dma->ch);

        kfree(tusb_dma);
}

struct dma_controller *__devinit
dma_controller_create(struct musb *musb, void __iomem *base)
{
        void __iomem            *tbase = musb->ctrl_base;
        struct tusb_omap_dma    *tusb_dma;
        int                     i;

        /* REVISIT: Get dmareq lines used from board-*.c */

        musb_writel(musb->ctrl_base, TUSB_DMA_INT_MASK, 0x7fffffff);
        musb_writel(musb->ctrl_base, TUSB_DMA_EP_MAP, 0);

        musb_writel(tbase, TUSB_DMA_REQ_CONF,
                TUSB_DMA_REQ_CONF_BURST_SIZE(2)
                | TUSB_DMA_REQ_CONF_DMA_REQ_EN(0x3f)
                | TUSB_DMA_REQ_CONF_DMA_REQ_ASSER(2));

        tusb_dma = kzalloc(sizeof(struct tusb_omap_dma), GFP_KERNEL);
        if (!tusb_dma)
                goto out;

        tusb_dma->musb = musb;
        tusb_dma->tbase = musb->ctrl_base;

        tusb_dma->ch = -1;
        tusb_dma->dmareq = -1;
        tusb_dma->sync_dev = -1;

        tusb_dma->controller.start = tusb_omap_dma_start;
        tusb_dma->controller.stop = tusb_omap_dma_stop;
        tusb_dma->controller.channel_alloc = tusb_omap_dma_allocate;
        tusb_dma->controller.channel_release = tusb_omap_dma_release;
        tusb_dma->controller.channel_program = tusb_omap_dma_program;
        tusb_dma->controller.channel_abort = tusb_omap_dma_abort;

        if (tusb_get_revision(musb) >= TUSB_REV_30)
                tusb_dma->multichannel = 1;

        for (i = 0; i < MAX_DMAREQ; i++) {
                struct dma_channel      *ch;
                struct tusb_omap_dma_ch *chdat;

                ch = kzalloc(sizeof(struct dma_channel), GFP_KERNEL);
                if (!ch)
                        goto cleanup;

                dma_channel_pool[i] = ch;

                chdat = kzalloc(sizeof(struct tusb_omap_dma_ch), GFP_KERNEL);
                if (!chdat)
                        goto cleanup;

                ch->status = MUSB_DMA_STATUS_UNKNOWN;
                ch->private_data = chdat;
        }

        return &tusb_dma->controller;

cleanup:
        dma_controller_destroy(&tusb_dma->controller);
out:
        return NULL;
}