ARM: 6656/1: hw_breakpoint: avoid UNPREDICTABLE behaviour when reading DBGDSCR

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / dma / amba-pl08x.c

/*
 * Copyright (c) 2006 ARM Ltd.
 * Copyright (c) 2010 ST-Ericsson SA
 *
 * Author: Peter Pearse <peter.pearse@arm.com>
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * The full GNU General Public License is in this distribution in the file
 * called COPYING.
 *
 * Documentation: ARM DDI 0196G == PL080
 * Documentation: ARM DDI 0218E == PL081
 *
 * PL080 & PL081 both have 16 sets of DMA signals that can be routed to any
 * channel.
 *
 * The PL080 has 8 channels available for simultaneous use, and the PL081
 * has only two channels. So on these DMA controllers the number of channels
 * and the number of incoming DMA signals are two totally different things.
 * It is usually not possible to theoretically handle all physical signals,
 * so a multiplexing scheme with possible denial of use is necessary.
 *
 * The PL080 has a dual bus master, PL081 has a single master.
 *
 * Memory to peripheral transfer may be visualized as
 *      Get data from memory to DMAC
 *      Until no data left
 *              On burst request from peripheral
 *                      Destination burst from DMAC to peripheral
 *                      Clear burst request
 *      Raise terminal count interrupt
 *
 * For peripherals with a FIFO:
 * Source      burst size == half the depth of the peripheral FIFO
 * Destination burst size == the depth of the peripheral FIFO
 *
 * (Bursts are irrelevant for mem to mem transfers - there are no burst
 * signals, the DMA controller will simply facilitate its AHB master.)
 *
 * ASSUMES default (little) endianness for DMA transfers
 *
 * The PL08x has two flow control settings:
 *  - DMAC flow control: the transfer size defines the number of transfers
 *    which occur for the current LLI entry, and the DMAC raises TC at the
 *    end of every LLI entry.  Observed behaviour shows the DMAC listening
 *    to both the BREQ and SREQ signals (contrary to documented),
 *    transferring data if either is active.  The LBREQ and LSREQ signals
 *    are ignored.
 *
 *  - Peripheral flow control: the transfer size is ignored (and should be
 *    zero).  The data is transferred from the current LLI entry, until
 *    after the final transfer signalled by LBREQ or LSREQ.  The DMAC
 *    will then move to the next LLI entry.
 *
 * Only the former works sanely with scatter lists, so we only implement
 * the DMAC flow control method.  However, peripherals which use the LBREQ
 * and LSREQ signals (eg, MMCI) are unable to use this mode, which through
 * these hardware restrictions prevents them from using scatter DMA.
 *
 * Global TODO:
 * - Break out common code from arch/arm/mach-s3c64xx and share
 */
#include <linux/device.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/dmapool.h>
#include <linux/dmaengine.h>
#include <linux/amba/bus.h>
#include <linux/amba/pl08x.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

#include <asm/hardware/pl080.h>

#define DRIVER_NAME     "pl08xdmac"

/**
 * struct vendor_data - vendor-specific config parameters for PL08x derivatives
 * @channels: the number of channels available in this variant
 * @dualmaster: whether this version supports dual AHB masters or not.
 */
struct vendor_data {
        u8 channels;
        bool dualmaster;
};

/*
 * PL08X private data structures
 * An LLI struct - see PL08x TRM.  Note that next uses bit[0] as a bus bit,
 * start & end do not - their bus bit info is in cctl.  Also note that these
 * are fixed 32-bit quantities.
 */
struct pl08x_lli {
        u32 src;
        u32 dst;
        u32 lli;
        u32 cctl;
};

/**
 * struct pl08x_driver_data - the local state holder for the PL08x
 * @slave: slave engine for this instance
 * @memcpy: memcpy engine for this instance
 * @base: virtual memory base (remapped) for the PL08x
 * @adev: the corresponding AMBA (PrimeCell) bus entry
 * @vd: vendor data for this PL08x variant
 * @pd: platform data passed in from the platform/machine
 * @phy_chans: array of data for the physical channels
 * @pool: a pool for the LLI descriptors
 * @pool_ctr: counter of LLIs in the pool
 * @lli_buses: bitmask to or in to LLI pointer selecting AHB port for LLI fetches
 * @mem_buses: set to indicate memory transfers on AHB2.
 * @lock: a spinlock for this struct
 */
struct pl08x_driver_data {
        struct dma_device slave;
        struct dma_device memcpy;
        void __iomem *base;
        struct amba_device *adev;
        const struct vendor_data *vd;
        struct pl08x_platform_data *pd;
        struct pl08x_phy_chan *phy_chans;
        struct dma_pool *pool;
        int pool_ctr;
        u8 lli_buses;
        u8 mem_buses;
        spinlock_t lock;
};

/*
 * PL08X specific defines
 */

/*
 * Memory boundaries: the manual for PL08x says that the controller
 * cannot read past a 1KiB boundary, so these defines are used to
 * create transfer LLIs that do not cross such boundaries.
 */
#define PL08X_BOUNDARY_SHIFT            (10)    /* 1KB 0x400 */
#define PL08X_BOUNDARY_SIZE             (1 << PL08X_BOUNDARY_SHIFT)

/* Minimum period between work queue runs */
#define PL08X_WQ_PERIODMIN      20

/* Size (bytes) of each LLI buffer allocated for one transfer */
# define PL08X_LLI_TSFR_SIZE    0x2000

/* Maximum times we call dma_pool_alloc on this pool without freeing */
#define PL08X_MAX_ALLOCS        0x40
#define MAX_NUM_TSFR_LLIS       (PL08X_LLI_TSFR_SIZE/sizeof(struct pl08x_lli))
#define PL08X_ALIGN             8

static inline struct pl08x_dma_chan *to_pl08x_chan(struct dma_chan *chan)
{
        return container_of(chan, struct pl08x_dma_chan, chan);
}

static inline struct pl08x_txd *to_pl08x_txd(struct dma_async_tx_descriptor *tx)
{
        return container_of(tx, struct pl08x_txd, tx);
}

/*
 * Physical channel handling
 */

/* Whether a certain channel is busy or not */
static int pl08x_phy_channel_busy(struct pl08x_phy_chan *ch)
{
        unsigned int val;

        val = readl(ch->base + PL080_CH_CONFIG);
        return val & PL080_CONFIG_ACTIVE;
}

/*
 * Set the initial DMA register values i.e. those for the first LLI
 * The next LLI pointer and the configuration interrupt bit have
 * been set when the LLIs were constructed.  Poke them into the hardware
 * and start the transfer.
 */
static void pl08x_start_txd(struct pl08x_dma_chan *plchan,
        struct pl08x_txd *txd)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_phy_chan *phychan = plchan->phychan;
        struct pl08x_lli *lli = &txd->llis_va[0];
        u32 val;

        plchan->at = txd;

        /* Wait for channel inactive */
        while (pl08x_phy_channel_busy(phychan))
                cpu_relax();

        dev_vdbg(&pl08x->adev->dev,
                "WRITE channel %d: csrc=0x%08x, cdst=0x%08x, "
                "clli=0x%08x, cctl=0x%08x, ccfg=0x%08x\n",
                phychan->id, lli->src, lli->dst, lli->lli, lli->cctl,
                txd->ccfg);

        writel(lli->src, phychan->base + PL080_CH_SRC_ADDR);
        writel(lli->dst, phychan->base + PL080_CH_DST_ADDR);
        writel(lli->lli, phychan->base + PL080_CH_LLI);
        writel(lli->cctl, phychan->base + PL080_CH_CONTROL);
        writel(txd->ccfg, phychan->base + PL080_CH_CONFIG);

        /* Enable the DMA channel */
        /* Do not access config register until channel shows as disabled */
        while (readl(pl08x->base + PL080_EN_CHAN) & (1 << phychan->id))
                cpu_relax();

        /* Do not access config register until channel shows as inactive */
        val = readl(phychan->base + PL080_CH_CONFIG);
        while ((val & PL080_CONFIG_ACTIVE) || (val & PL080_CONFIG_ENABLE))
                val = readl(phychan->base + PL080_CH_CONFIG);

        writel(val | PL080_CONFIG_ENABLE, phychan->base + PL080_CH_CONFIG);
}

/*
 * Overall DMAC remains enabled always.
 *
 * Disabling individual channels could lose data.
 *
 * Disable the peripheral DMA after disabling the DMAC in order to allow
 * the DMAC FIFO to drain, and hence allow the channel to show inactive
 */
static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch)
{
        u32 val;

        /* Set the HALT bit and wait for the FIFO to drain */
        val = readl(ch->base + PL080_CH_CONFIG);
        val |= PL080_CONFIG_HALT;
        writel(val, ch->base + PL080_CH_CONFIG);

        /* Wait for channel inactive */
        while (pl08x_phy_channel_busy(ch))
                cpu_relax();
}

static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch)
{
        u32 val;

        /* Clear the HALT bit */
        val = readl(ch->base + PL080_CH_CONFIG);
        val &= ~PL080_CONFIG_HALT;
        writel(val, ch->base + PL080_CH_CONFIG);
}


/* Stops the channel */
static void pl08x_stop_phy_chan(struct pl08x_phy_chan *ch)
{
        u32 val;

        pl08x_pause_phy_chan(ch);

        /* Disable channel */
        val = readl(ch->base + PL080_CH_CONFIG);
        val &= ~PL080_CONFIG_ENABLE;
        val &= ~PL080_CONFIG_ERR_IRQ_MASK;
        val &= ~PL080_CONFIG_TC_IRQ_MASK;
        writel(val, ch->base + PL080_CH_CONFIG);
}

static inline u32 get_bytes_in_cctl(u32 cctl)
{
        /* The source width defines the number of bytes */
        u32 bytes = cctl & PL080_CONTROL_TRANSFER_SIZE_MASK;

        switch (cctl >> PL080_CONTROL_SWIDTH_SHIFT) {
        case PL080_WIDTH_8BIT:
                break;
        case PL080_WIDTH_16BIT:
                bytes *= 2;
                break;
        case PL080_WIDTH_32BIT:
                bytes *= 4;
                break;
        }
        return bytes;
}

/* The channel should be paused when calling this */
static u32 pl08x_getbytes_chan(struct pl08x_dma_chan *plchan)
{
        struct pl08x_phy_chan *ch;
        struct pl08x_txd *txd;
        unsigned long flags;
        size_t bytes = 0;

        spin_lock_irqsave(&plchan->lock, flags);
        ch = plchan->phychan;
        txd = plchan->at;

        /*
         * Follow the LLIs to get the number of remaining
         * bytes in the currently active transaction.
         */
        if (ch && txd) {
                u32 clli = readl(ch->base + PL080_CH_LLI) & ~PL080_LLI_LM_AHB2;

                /* First get the remaining bytes in the active transfer */
                bytes = get_bytes_in_cctl(readl(ch->base + PL080_CH_CONTROL));

                if (clli) {
                        struct pl08x_lli *llis_va = txd->llis_va;
                        dma_addr_t llis_bus = txd->llis_bus;
                        int index;

                        BUG_ON(clli < llis_bus || clli >= llis_bus +
                                sizeof(struct pl08x_lli) * MAX_NUM_TSFR_LLIS);

                        /*
                         * Locate the next LLI - as this is an array,
                         * it's simple maths to find.
                         */
                        index = (clli - llis_bus) / sizeof(struct pl08x_lli);

                        for (; index < MAX_NUM_TSFR_LLIS; index++) {
                                bytes += get_bytes_in_cctl(llis_va[index].cctl);

                                /*
                                 * A LLI pointer of 0 terminates the LLI list
                                 */
                                if (!llis_va[index].lli)
                                        break;
                        }
                }
        }

        /* Sum up all queued transactions */
        if (!list_empty(&plchan->pend_list)) {
                struct pl08x_txd *txdi;
                list_for_each_entry(txdi, &plchan->pend_list, node) {
                        bytes += txdi->len;
                }
        }

        spin_unlock_irqrestore(&plchan->lock, flags);

        return bytes;
}

/*
 * Allocate a physical channel for a virtual channel
 *
 * Try to locate a physical channel to be used for this transfer. If all
 * are taken return NULL and the requester will have to cope by using
 * some fallback PIO mode or retrying later.
 */
static struct pl08x_phy_chan *
pl08x_get_phy_channel(struct pl08x_driver_data *pl08x,
                      struct pl08x_dma_chan *virt_chan)
{
        struct pl08x_phy_chan *ch = NULL;
        unsigned long flags;
        int i;

        for (i = 0; i < pl08x->vd->channels; i++) {
                ch = &pl08x->phy_chans[i];

                spin_lock_irqsave(&ch->lock, flags);

                if (!ch->serving) {
                        ch->serving = virt_chan;
                        ch->signal = -1;
                        spin_unlock_irqrestore(&ch->lock, flags);
                        break;
                }

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

        if (i == pl08x->vd->channels) {
                /* No physical channel available, cope with it */
                return NULL;
        }

        return ch;
}

static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x,
                                         struct pl08x_phy_chan *ch)
{
        unsigned long flags;

        /* Stop the channel and clear its interrupts */
        pl08x_stop_phy_chan(ch);
        writel((1 << ch->id), pl08x->base + PL080_ERR_CLEAR);
        writel((1 << ch->id), pl08x->base + PL080_TC_CLEAR);

        /* Mark it as free */
        spin_lock_irqsave(&ch->lock, flags);
        ch->serving = NULL;
        spin_unlock_irqrestore(&ch->lock, flags);
}

/*
 * LLI handling
 */

static inline unsigned int pl08x_get_bytes_for_cctl(unsigned int coded)
{
        switch (coded) {
        case PL080_WIDTH_8BIT:
                return 1;
        case PL080_WIDTH_16BIT:
                return 2;
        case PL080_WIDTH_32BIT:
                return 4;
        default:
                break;
        }
        BUG();
        return 0;
}

static inline u32 pl08x_cctl_bits(u32 cctl, u8 srcwidth, u8 dstwidth,
                                  size_t tsize)
{
        u32 retbits = cctl;

        /* Remove all src, dst and transfer size bits */
        retbits &= ~PL080_CONTROL_DWIDTH_MASK;
        retbits &= ~PL080_CONTROL_SWIDTH_MASK;
        retbits &= ~PL080_CONTROL_TRANSFER_SIZE_MASK;

        /* Then set the bits according to the parameters */
        switch (srcwidth) {
        case 1:
                retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        case 2:
                retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        case 4:
                retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        default:
                BUG();
                break;
        }

        switch (dstwidth) {
        case 1:
                retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        case 2:
                retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        case 4:
                retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        default:
                BUG();
                break;
        }

        retbits |= tsize << PL080_CONTROL_TRANSFER_SIZE_SHIFT;
        return retbits;
}

struct pl08x_lli_build_data {
        struct pl08x_txd *txd;
        struct pl08x_driver_data *pl08x;
        struct pl08x_bus_data srcbus;
        struct pl08x_bus_data dstbus;
        size_t remainder;
};

/*
 * Autoselect a master bus to use for the transfer this prefers the
 * destination bus if both available if fixed address on one bus the
 * other will be chosen
 */
static void pl08x_choose_master_bus(struct pl08x_lli_build_data *bd,
        struct pl08x_bus_data **mbus, struct pl08x_bus_data **sbus, u32 cctl)
{
        if (!(cctl & PL080_CONTROL_DST_INCR)) {
                *mbus = &bd->srcbus;
                *sbus = &bd->dstbus;
        } else if (!(cctl & PL080_CONTROL_SRC_INCR)) {
                *mbus = &bd->dstbus;
                *sbus = &bd->srcbus;
        } else {
                if (bd->dstbus.buswidth == 4) {
                        *mbus = &bd->dstbus;
                        *sbus = &bd->srcbus;
                } else if (bd->srcbus.buswidth == 4) {
                        *mbus = &bd->srcbus;
                        *sbus = &bd->dstbus;
                } else if (bd->dstbus.buswidth == 2) {
                        *mbus = &bd->dstbus;
                        *sbus = &bd->srcbus;
                } else if (bd->srcbus.buswidth == 2) {
                        *mbus = &bd->srcbus;
                        *sbus = &bd->dstbus;
                } else {
                        /* bd->srcbus.buswidth == 1 */
                        *mbus = &bd->dstbus;
                        *sbus = &bd->srcbus;
                }
        }
}

/*
 * Fills in one LLI for a certain transfer descriptor and advance the counter
 */
static void pl08x_fill_lli_for_desc(struct pl08x_lli_build_data *bd,
        int num_llis, int len, u32 cctl)
{
        struct pl08x_lli *llis_va = bd->txd->llis_va;
        dma_addr_t llis_bus = bd->txd->llis_bus;

        BUG_ON(num_llis >= MAX_NUM_TSFR_LLIS);

        llis_va[num_llis].cctl = cctl;
        llis_va[num_llis].src = bd->srcbus.addr;
        llis_va[num_llis].dst = bd->dstbus.addr;
        llis_va[num_llis].lli = llis_bus + (num_llis + 1) * sizeof(struct pl08x_lli);
        if (bd->pl08x->lli_buses & PL08X_AHB2)
                llis_va[num_llis].lli |= PL080_LLI_LM_AHB2;

        if (cctl & PL080_CONTROL_SRC_INCR)
                bd->srcbus.addr += len;
        if (cctl & PL080_CONTROL_DST_INCR)
                bd->dstbus.addr += len;

        BUG_ON(bd->remainder < len);

        bd->remainder -= len;
}

/*
 * Return number of bytes to fill to boundary, or len.
 * This calculation works for any value of addr.
 */
static inline size_t pl08x_pre_boundary(u32 addr, size_t len)
{
        size_t boundary_len = PL08X_BOUNDARY_SIZE -
                        (addr & (PL08X_BOUNDARY_SIZE - 1));

        return min(boundary_len, len);
}

/*
 * This fills in the table of LLIs for the transfer descriptor
 * Note that we assume we never have to change the burst sizes
 * Return 0 for error
 */
static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x,
                              struct pl08x_txd *txd)
{
        struct pl08x_bus_data *mbus, *sbus;
        struct pl08x_lli_build_data bd;
        int num_llis = 0;
        u32 cctl;
        size_t max_bytes_per_lli;
        size_t total_bytes = 0;
        struct pl08x_lli *llis_va;

        txd->llis_va = dma_pool_alloc(pl08x->pool, GFP_NOWAIT,
                                      &txd->llis_bus);
        if (!txd->llis_va) {
                dev_err(&pl08x->adev->dev, "%s no memory for llis\n", __func__);
                return 0;
        }

        pl08x->pool_ctr++;

        /* Get the default CCTL */
        cctl = txd->cctl;

        bd.txd = txd;
        bd.pl08x = pl08x;
        bd.srcbus.addr = txd->src_addr;
        bd.dstbus.addr = txd->dst_addr;

        /* Find maximum width of the source bus */
        bd.srcbus.maxwidth =
                pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_SWIDTH_MASK) >>
                                       PL080_CONTROL_SWIDTH_SHIFT);

        /* Find maximum width of the destination bus */
        bd.dstbus.maxwidth =
                pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_DWIDTH_MASK) >>
                                       PL080_CONTROL_DWIDTH_SHIFT);

        /* Set up the bus widths to the maximum */
        bd.srcbus.buswidth = bd.srcbus.maxwidth;
        bd.dstbus.buswidth = bd.dstbus.maxwidth;
        dev_vdbg(&pl08x->adev->dev,
                 "%s source bus is %d bytes wide, dest bus is %d bytes wide\n",
                 __func__, bd.srcbus.buswidth, bd.dstbus.buswidth);


        /*
         * Bytes transferred == tsize * MIN(buswidths), not max(buswidths)
         */
        max_bytes_per_lli = min(bd.srcbus.buswidth, bd.dstbus.buswidth) *
                PL080_CONTROL_TRANSFER_SIZE_MASK;
        dev_vdbg(&pl08x->adev->dev,
                 "%s max bytes per lli = %zu\n",
                 __func__, max_bytes_per_lli);

        /* We need to count this down to zero */
        bd.remainder = txd->len;
        dev_vdbg(&pl08x->adev->dev,
                 "%s remainder = %zu\n",
                 __func__, bd.remainder);

        /*
         * Choose bus to align to
         * - prefers destination bus if both available
         * - if fixed address on one bus chooses other
         */
        pl08x_choose_master_bus(&bd, &mbus, &sbus, cctl);

        if (txd->len < mbus->buswidth) {
                /* Less than a bus width available - send as single bytes */
                while (bd.remainder) {
                        dev_vdbg(&pl08x->adev->dev,
                                 "%s single byte LLIs for a transfer of "
                                 "less than a bus width (remain 0x%08x)\n",
                                 __func__, bd.remainder);
                        cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
                        pl08x_fill_lli_for_desc(&bd, num_llis++, 1, cctl);
                        total_bytes++;
                }
        } else {
                /* Make one byte LLIs until master bus is aligned */
                while ((mbus->addr) % (mbus->buswidth)) {
                        dev_vdbg(&pl08x->adev->dev,
                                "%s adjustment lli for less than bus width "
                                 "(remain 0x%08x)\n",
                                 __func__, bd.remainder);
                        cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
                        pl08x_fill_lli_for_desc(&bd, num_llis++, 1, cctl);
                        total_bytes++;
                }

                /*
                 * Master now aligned
                 * - if slave is not then we must set its width down
                 */
                if (sbus->addr % sbus->buswidth) {
                        dev_dbg(&pl08x->adev->dev,
                                "%s set down bus width to one byte\n",
                                 __func__);

                        sbus->buswidth = 1;
                }

                /*
                 * Make largest possible LLIs until less than one bus
                 * width left
                 */
                while (bd.remainder > (mbus->buswidth - 1)) {
                        size_t lli_len, target_len, tsize, odd_bytes;

                        /*
                         * If enough left try to send max possible,
                         * otherwise try to send the remainder
                         */
                        target_len = min(bd.remainder, max_bytes_per_lli);

                        /*
                         * Set bus lengths for incrementing buses to the
                         * number of bytes which fill to next memory boundary,
                         * limiting on the target length calculated above.
                         */
                        if (cctl & PL080_CONTROL_SRC_INCR)
                                bd.srcbus.fill_bytes =
                                        pl08x_pre_boundary(bd.srcbus.addr,
                                                target_len);
                        else
                                bd.srcbus.fill_bytes = target_len;

                        if (cctl & PL080_CONTROL_DST_INCR)
                                bd.dstbus.fill_bytes =
                                        pl08x_pre_boundary(bd.dstbus.addr,
                                                target_len);
                        else
                                bd.dstbus.fill_bytes = target_len;

                        /* Find the nearest */
                        lli_len = min(bd.srcbus.fill_bytes,
                                      bd.dstbus.fill_bytes);

                        BUG_ON(lli_len > bd.remainder);

                        if (lli_len <= 0) {
                                dev_err(&pl08x->adev->dev,
                                        "%s lli_len is %zu, <= 0\n",
                                                __func__, lli_len);
                                return 0;
                        }

                        if (lli_len == target_len) {
                                /*
                                 * Can send what we wanted.
                                 * Maintain alignment
                                 */
                                lli_len = (lli_len/mbus->buswidth) *
                                                        mbus->buswidth;
                                odd_bytes = 0;
                        } else {
                                /*
                                 * So now we know how many bytes to transfer
                                 * to get to the nearest boundary.  The next
                                 * LLI will past the boundary.  However, we
                                 * may be working to a boundary on the slave
                                 * bus.  We need to ensure the master stays
                                 * aligned, and that we are working in
                                 * multiples of the bus widths.
                                 */
                                odd_bytes = lli_len % mbus->buswidth;
                                lli_len -= odd_bytes;

                        }

                        if (lli_len) {
                                /*
                                 * Check against minimum bus alignment:
                                 * Calculate actual transfer size in relation
                                 * to bus width an get a maximum remainder of
                                 * the smallest bus width - 1
                                 */
                                /* FIXME: use round_down()? */
                                tsize = lli_len / min(mbus->buswidth,
                                                      sbus->buswidth);
                                lli_len = tsize * min(mbus->buswidth,
                                                      sbus->buswidth);

                                if (target_len != lli_len) {
                                        dev_vdbg(&pl08x->adev->dev,
                                        "%s can't send what we want. Desired 0x%08zx, lli of 0x%08zx bytes in txd of 0x%08zx\n",
                                        __func__, target_len, lli_len, txd->len);
                                }

                                cctl = pl08x_cctl_bits(cctl,
                                                       bd.srcbus.buswidth,
                                                       bd.dstbus.buswidth,
                                                       tsize);

                                dev_vdbg(&pl08x->adev->dev,
                                        "%s fill lli with single lli chunk of size 0x%08zx (remainder 0x%08zx)\n",
                                        __func__, lli_len, bd.remainder);
                                pl08x_fill_lli_for_desc(&bd, num_llis++,
                                        lli_len, cctl);
                                total_bytes += lli_len;
                        }


                        if (odd_bytes) {
                                /*
                                 * Creep past the boundary, maintaining
                                 * master alignment
                                 */
                                int j;
                                for (j = 0; (j < mbus->buswidth)
                                                && (bd.remainder); j++) {
                                        cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
                                        dev_vdbg(&pl08x->adev->dev,
                                                "%s align with boundary, single byte (remain 0x%08zx)\n",
                                                __func__, bd.remainder);
                                        pl08x_fill_lli_for_desc(&bd,
                                                num_llis++, 1, cctl);
                                        total_bytes++;
                                }
                        }
                }

                /*
                 * Send any odd bytes
                 */
                while (bd.remainder) {
                        cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
                        dev_vdbg(&pl08x->adev->dev,
                                "%s align with boundary, single odd byte (remain %zu)\n",
                                __func__, bd.remainder);
                        pl08x_fill_lli_for_desc(&bd, num_llis++, 1, cctl);
                        total_bytes++;
                }
        }
        if (total_bytes != txd->len) {
                dev_err(&pl08x->adev->dev,
                        "%s size of encoded lli:s don't match total txd, transferred 0x%08zx from size 0x%08zx\n",
                        __func__, total_bytes, txd->len);
                return 0;
        }

        if (num_llis >= MAX_NUM_TSFR_LLIS) {
                dev_err(&pl08x->adev->dev,
                        "%s need to increase MAX_NUM_TSFR_LLIS from 0x%08x\n",
                        __func__, (u32) MAX_NUM_TSFR_LLIS);
                return 0;
        }

        llis_va = txd->llis_va;
        /* The final LLI terminates the LLI. */
        llis_va[num_llis - 1].lli = 0;
        /* The final LLI element shall also fire an interrupt. */
        llis_va[num_llis - 1].cctl |= PL080_CONTROL_TC_IRQ_EN;

#ifdef VERBOSE_DEBUG
        {
                int i;

                for (i = 0; i < num_llis; i++) {
                        dev_vdbg(&pl08x->adev->dev,
                                 "lli %d @%p: csrc=0x%08x, cdst=0x%08x, cctl=0x%08x, clli=0x%08x\n",
                                 i,
                                 &llis_va[i],
                                 llis_va[i].src,
                                 llis_va[i].dst,
                                 llis_va[i].cctl,
                                 llis_va[i].lli
                                );
                }
        }
#endif

        return num_llis;
}

/* You should call this with the struct pl08x lock held */
static void pl08x_free_txd(struct pl08x_driver_data *pl08x,
                           struct pl08x_txd *txd)
{
        /* Free the LLI */
        dma_pool_free(pl08x->pool, txd->llis_va, txd->llis_bus);

        pl08x->pool_ctr--;

        kfree(txd);
}

static void pl08x_free_txd_list(struct pl08x_driver_data *pl08x,
                                struct pl08x_dma_chan *plchan)
{
        struct pl08x_txd *txdi = NULL;
        struct pl08x_txd *next;

        if (!list_empty(&plchan->pend_list)) {
                list_for_each_entry_safe(txdi,
                                         next, &plchan->pend_list, node) {
                        list_del(&txdi->node);
                        pl08x_free_txd(pl08x, txdi);
                }
        }
}

/*
 * The DMA ENGINE API
 */
static int pl08x_alloc_chan_resources(struct dma_chan *chan)
{
        return 0;
}

static void pl08x_free_chan_resources(struct dma_chan *chan)
{
}

/*
 * This should be called with the channel plchan->lock held
 */
static int prep_phy_channel(struct pl08x_dma_chan *plchan,
                            struct pl08x_txd *txd)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_phy_chan *ch;
        int ret;

        /* Check if we already have a channel */
        if (plchan->phychan)
                return 0;

        ch = pl08x_get_phy_channel(pl08x, plchan);
        if (!ch) {
                /* No physical channel available, cope with it */
                dev_dbg(&pl08x->adev->dev, "no physical channel available for xfer on %s\n", plchan->name);
                return -EBUSY;
        }

        /*
         * OK we have a physical channel: for memcpy() this is all we
         * need, but for slaves the physical signals may be muxed!
         * Can the platform allow us to use this channel?
         */
        if (plchan->slave &&
            ch->signal < 0 &&
            pl08x->pd->get_signal) {
                ret = pl08x->pd->get_signal(plchan);
                if (ret < 0) {
                        dev_dbg(&pl08x->adev->dev,
                                "unable to use physical channel %d for transfer on %s due to platform restrictions\n",
                                ch->id, plchan->name);
                        /* Release physical channel & return */
                        pl08x_put_phy_channel(pl08x, ch);
                        return -EBUSY;
                }
                ch->signal = ret;

                /* Assign the flow control signal to this channel */
                if (txd->direction == DMA_TO_DEVICE)
                        txd->ccfg |= ch->signal << PL080_CONFIG_DST_SEL_SHIFT;
                else if (txd->direction == DMA_FROM_DEVICE)
                        txd->ccfg |= ch->signal << PL080_CONFIG_SRC_SEL_SHIFT;
        }

        dev_dbg(&pl08x->adev->dev, "allocated physical channel %d and signal %d for xfer on %s\n",
                 ch->id,
                 ch->signal,
                 plchan->name);

        plchan->phychan_hold++;
        plchan->phychan = ch;

        return 0;
}

static void release_phy_channel(struct pl08x_dma_chan *plchan)
{
        struct pl08x_driver_data *pl08x = plchan->host;

        if ((plchan->phychan->signal >= 0) && pl08x->pd->put_signal) {
                pl08x->pd->put_signal(plchan);
                plchan->phychan->signal = -1;
        }
        pl08x_put_phy_channel(pl08x, plchan->phychan);
        plchan->phychan = NULL;
}

static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(tx->chan);
        struct pl08x_txd *txd = to_pl08x_txd(tx);
        unsigned long flags;

        spin_lock_irqsave(&plchan->lock, flags);

        plchan->chan.cookie += 1;
        if (plchan->chan.cookie < 0)
                plchan->chan.cookie = 1;
        tx->cookie = plchan->chan.cookie;

        /* Put this onto the pending list */
        list_add_tail(&txd->node, &plchan->pend_list);

        /*
         * If there was no physical channel available for this memcpy,
         * stack the request up and indicate that the channel is waiting
         * for a free physical channel.
         */
        if (!plchan->slave && !plchan->phychan) {
                /* Do this memcpy whenever there is a channel ready */
                plchan->state = PL08X_CHAN_WAITING;
                plchan->waiting = txd;
        } else {
                plchan->phychan_hold--;
        }

        spin_unlock_irqrestore(&plchan->lock, flags);

        return tx->cookie;
}

static struct dma_async_tx_descriptor *pl08x_prep_dma_interrupt(
                struct dma_chan *chan, unsigned long flags)
{
        struct dma_async_tx_descriptor *retval = NULL;

        return retval;
}

/*
 * Code accessing dma_async_is_complete() in a tight loop may give problems.
 * If slaves are relying on interrupts to signal completion this function
 * must not be called with interrupts disabled.
 */
static enum dma_status
pl08x_dma_tx_status(struct dma_chan *chan,
                    dma_cookie_t cookie,
                    struct dma_tx_state *txstate)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        dma_cookie_t last_used;
        dma_cookie_t last_complete;
        enum dma_status ret;
        u32 bytesleft = 0;

        last_used = plchan->chan.cookie;
        last_complete = plchan->lc;

        ret = dma_async_is_complete(cookie, last_complete, last_used);
        if (ret == DMA_SUCCESS) {
                dma_set_tx_state(txstate, last_complete, last_used, 0);
                return ret;
        }

        /*
         * This cookie not complete yet
         */
        last_used = plchan->chan.cookie;
        last_complete = plchan->lc;

        /* Get number of bytes left in the active transactions and queue */
        bytesleft = pl08x_getbytes_chan(plchan);

        dma_set_tx_state(txstate, last_complete, last_used,
                         bytesleft);

        if (plchan->state == PL08X_CHAN_PAUSED)
                return DMA_PAUSED;

        /* Whether waiting or running, we're in progress */
        return DMA_IN_PROGRESS;
}

/* PrimeCell DMA extension */
struct burst_table {
        int burstwords;
        u32 reg;
};

static const struct burst_table burst_sizes[] = {
        {
                .burstwords = 256,
                .reg = (PL080_BSIZE_256 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_256 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 128,
                .reg = (PL080_BSIZE_128 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_128 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 64,
                .reg = (PL080_BSIZE_64 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_64 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 32,
                .reg = (PL080_BSIZE_32 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_32 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 16,
                .reg = (PL080_BSIZE_16 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_16 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 8,
                .reg = (PL080_BSIZE_8 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_8 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 4,
                .reg = (PL080_BSIZE_4 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_4 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
        {
                .burstwords = 1,
                .reg = (PL080_BSIZE_1 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_1 << PL080_CONTROL_DB_SIZE_SHIFT),
        },
};

static int dma_set_runtime_config(struct dma_chan *chan,
                                  struct dma_slave_config *config)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_channel_data *cd = plchan->cd;
        enum dma_slave_buswidth addr_width;
        dma_addr_t addr;
        u32 maxburst;
        u32 cctl = 0;
        int i;

        if (!plchan->slave)
                return -EINVAL;

        /* Transfer direction */
        plchan->runtime_direction = config->direction;
        if (config->direction == DMA_TO_DEVICE) {
                addr = config->dst_addr;
                addr_width = config->dst_addr_width;
                maxburst = config->dst_maxburst;
        } else if (config->direction == DMA_FROM_DEVICE) {
                addr = config->src_addr;
                addr_width = config->src_addr_width;
                maxburst = config->src_maxburst;
        } else {
                dev_err(&pl08x->adev->dev,
                        "bad runtime_config: alien transfer direction\n");
                return -EINVAL;
        }

        switch (addr_width) {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                cctl |= (PL080_WIDTH_8BIT << PL080_CONTROL_SWIDTH_SHIFT) |
                        (PL080_WIDTH_8BIT << PL080_CONTROL_DWIDTH_SHIFT);
                break;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                cctl |= (PL080_WIDTH_16BIT << PL080_CONTROL_SWIDTH_SHIFT) |
                        (PL080_WIDTH_16BIT << PL080_CONTROL_DWIDTH_SHIFT);
                break;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                cctl |= (PL080_WIDTH_32BIT << PL080_CONTROL_SWIDTH_SHIFT) |
                        (PL080_WIDTH_32BIT << PL080_CONTROL_DWIDTH_SHIFT);
                break;
        default:
                dev_err(&pl08x->adev->dev,
                        "bad runtime_config: alien address width\n");
                return -EINVAL;
        }

        /*
         * Now decide on a maxburst:
         * If this channel will only request single transfers, set this
         * down to ONE element.  Also select one element if no maxburst
         * is specified.
         */
        if (plchan->cd->single || maxburst == 0) {
                cctl |= (PL080_BSIZE_1 << PL080_CONTROL_SB_SIZE_SHIFT) |
                        (PL080_BSIZE_1 << PL080_CONTROL_DB_SIZE_SHIFT);
        } else {
                for (i = 0; i < ARRAY_SIZE(burst_sizes); i++)
                        if (burst_sizes[i].burstwords <= maxburst)
                                break;
                cctl |= burst_sizes[i].reg;
        }

        plchan->runtime_addr = addr;

        /* Modify the default channel data to fit PrimeCell request */
        cd->cctl = cctl;

        dev_dbg(&pl08x->adev->dev,
                "configured channel %s (%s) for %s, data width %d, "
                "maxburst %d words, LE, CCTL=0x%08x\n",
                dma_chan_name(chan), plchan->name,
                (config->direction == DMA_FROM_DEVICE) ? "RX" : "TX",
                addr_width,
                maxburst,
                cctl);

        return 0;
}

/*
 * Slave transactions callback to the slave device to allow
 * synchronization of slave DMA signals with the DMAC enable
 */
static void pl08x_issue_pending(struct dma_chan *chan)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&plchan->lock, flags);
        /* Something is already active, or we're waiting for a channel... */
        if (plchan->at || plchan->state == PL08X_CHAN_WAITING) {
                spin_unlock_irqrestore(&plchan->lock, flags);
                return;
        }

        /* Take the first element in the queue and execute it */
        if (!list_empty(&plchan->pend_list)) {
                struct pl08x_txd *next;

                next = list_first_entry(&plchan->pend_list,
                                        struct pl08x_txd,
                                        node);
                list_del(&next->node);
                plchan->state = PL08X_CHAN_RUNNING;

                pl08x_start_txd(plchan, next);
        }

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

static int pl08x_prep_channel_resources(struct pl08x_dma_chan *plchan,
                                        struct pl08x_txd *txd)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        unsigned long flags;
        int num_llis, ret;

        num_llis = pl08x_fill_llis_for_desc(pl08x, txd);
        if (!num_llis) {
                kfree(txd);
                return -EINVAL;
        }

        spin_lock_irqsave(&plchan->lock, flags);

        /*
         * See if we already have a physical channel allocated,
         * else this is the time to try to get one.
         */
        ret = prep_phy_channel(plchan, txd);
        if (ret) {
                /*
                 * No physical channel was available.
                 *
                 * memcpy transfers can be sorted out at submission time.
                 *
                 * Slave transfers may have been denied due to platform
                 * channel muxing restrictions.  Since there is no guarantee
                 * that this will ever be resolved, and the signal must be
                 * acquired AFTER acquiring the physical channel, we will let
                 * them be NACK:ed with -EBUSY here. The drivers can retry
                 * the prep() call if they are eager on doing this using DMA.
                 */
                if (plchan->slave) {
                        pl08x_free_txd_list(pl08x, plchan);
                        pl08x_free_txd(pl08x, txd);
                        spin_unlock_irqrestore(&plchan->lock, flags);
                        return -EBUSY;
                }
        } else
                /*
                 * Else we're all set, paused and ready to roll, status
                 * will switch to PL08X_CHAN_RUNNING when we call
                 * issue_pending(). If there is something running on the
                 * channel already we don't change its state.
                 */
                if (plchan->state == PL08X_CHAN_IDLE)
                        plchan->state = PL08X_CHAN_PAUSED;

        spin_unlock_irqrestore(&plchan->lock, flags);

        return 0;
}

/*
 * Given the source and destination available bus masks, select which
 * will be routed to each port.  We try to have source and destination
 * on separate ports, but always respect the allowable settings.
 */
static u32 pl08x_select_bus(struct pl08x_driver_data *pl08x, u8 src, u8 dst)
{
        u32 cctl = 0;

        if (!(dst & PL08X_AHB1) || ((dst & PL08X_AHB2) && (src & PL08X_AHB1)))
                cctl |= PL080_CONTROL_DST_AHB2;
        if (!(src & PL08X_AHB1) || ((src & PL08X_AHB2) && !(dst & PL08X_AHB2)))
                cctl |= PL080_CONTROL_SRC_AHB2;

        return cctl;
}

static struct pl08x_txd *pl08x_get_txd(struct pl08x_dma_chan *plchan,
        unsigned long flags)
{
        struct pl08x_txd *txd = kzalloc(sizeof(struct pl08x_txd), GFP_NOWAIT);

        if (txd) {
                dma_async_tx_descriptor_init(&txd->tx, &plchan->chan);
                txd->tx.flags = flags;
                txd->tx.tx_submit = pl08x_tx_submit;
                INIT_LIST_HEAD(&txd->node);

                /* Always enable error and terminal interrupts */
                txd->ccfg = PL080_CONFIG_ERR_IRQ_MASK |
                            PL080_CONFIG_TC_IRQ_MASK;
        }
        return txd;
}

/*
 * Initialize a descriptor to be used by memcpy submit
 */
static struct dma_async_tx_descriptor *pl08x_prep_dma_memcpy(
                struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                size_t len, unsigned long flags)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_txd *txd;
        int ret;

        txd = pl08x_get_txd(plchan, flags);
        if (!txd) {
                dev_err(&pl08x->adev->dev,
                        "%s no memory for descriptor\n", __func__);
                return NULL;
        }

        txd->direction = DMA_NONE;
        txd->src_addr = src;
        txd->dst_addr = dest;
        txd->len = len;

        /* Set platform data for m2m */
        txd->ccfg |= PL080_FLOW_MEM2MEM << PL080_CONFIG_FLOW_CONTROL_SHIFT;
        txd->cctl = pl08x->pd->memcpy_channel.cctl &
                        ~(PL080_CONTROL_DST_AHB2 | PL080_CONTROL_SRC_AHB2);

        /* Both to be incremented or the code will break */
        txd->cctl |= PL080_CONTROL_SRC_INCR | PL080_CONTROL_DST_INCR;

        if (pl08x->vd->dualmaster)
                txd->cctl |= pl08x_select_bus(pl08x,
                                        pl08x->mem_buses, pl08x->mem_buses);

        ret = pl08x_prep_channel_resources(plchan, txd);
        if (ret)
                return NULL;

        return &txd->tx;
}

static struct dma_async_tx_descriptor *pl08x_prep_slave_sg(
                struct dma_chan *chan, struct scatterlist *sgl,
                unsigned int sg_len, enum dma_data_direction direction,
                unsigned long flags)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_txd *txd;
        u8 src_buses, dst_buses;
        int ret;

        /*
         * Current implementation ASSUMES only one sg
         */
        if (sg_len != 1) {
                dev_err(&pl08x->adev->dev, "%s prepared too long sglist\n",
                        __func__);
                BUG();
        }

        dev_dbg(&pl08x->adev->dev, "%s prepare transaction of %d bytes from %s\n",
                __func__, sgl->length, plchan->name);

        txd = pl08x_get_txd(plchan, flags);
        if (!txd) {
                dev_err(&pl08x->adev->dev, "%s no txd\n", __func__);
                return NULL;
        }

        if (direction != plchan->runtime_direction)
                dev_err(&pl08x->adev->dev, "%s DMA setup does not match "
                        "the direction configured for the PrimeCell\n",
                        __func__);

        /*
         * Set up addresses, the PrimeCell configured address
         * will take precedence since this may configure the
         * channel target address dynamically at runtime.
         */
        txd->direction = direction;
        txd->len = sgl->length;

        txd->cctl = plchan->cd->cctl &
                        ~(PL080_CONTROL_SRC_AHB2 | PL080_CONTROL_DST_AHB2 |
                          PL080_CONTROL_SRC_INCR | PL080_CONTROL_DST_INCR |
                          PL080_CONTROL_PROT_MASK);

        /* Access the cell in privileged mode, non-bufferable, non-cacheable */
        txd->cctl |= PL080_CONTROL_PROT_SYS;

        if (direction == DMA_TO_DEVICE) {
                txd->ccfg |= PL080_FLOW_MEM2PER << PL080_CONFIG_FLOW_CONTROL_SHIFT;
                txd->cctl |= PL080_CONTROL_SRC_INCR;
                txd->src_addr = sgl->dma_address;
                if (plchan->runtime_addr)
                        txd->dst_addr = plchan->runtime_addr;
                else
                        txd->dst_addr = plchan->cd->addr;
                src_buses = pl08x->mem_buses;
                dst_buses = plchan->cd->periph_buses;
        } else if (direction == DMA_FROM_DEVICE) {
                txd->ccfg |= PL080_FLOW_PER2MEM << PL080_CONFIG_FLOW_CONTROL_SHIFT;
                txd->cctl |= PL080_CONTROL_DST_INCR;
                if (plchan->runtime_addr)
                        txd->src_addr = plchan->runtime_addr;
                else
                        txd->src_addr = plchan->cd->addr;
                txd->dst_addr = sgl->dma_address;
                src_buses = plchan->cd->periph_buses;
                dst_buses = pl08x->mem_buses;
        } else {
                dev_err(&pl08x->adev->dev,
                        "%s direction unsupported\n", __func__);
                return NULL;
        }

        txd->cctl |= pl08x_select_bus(pl08x, src_buses, dst_buses);

        ret = pl08x_prep_channel_resources(plchan, txd);
        if (ret)
                return NULL;

        return &txd->tx;
}

static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                         unsigned long arg)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        unsigned long flags;
        int ret = 0;

        /* Controls applicable to inactive channels */
        if (cmd == DMA_SLAVE_CONFIG) {
                return dma_set_runtime_config(chan,
                                              (struct dma_slave_config *)arg);
        }

        /*
         * Anything succeeds on channels with no physical allocation and
         * no queued transfers.
         */
        spin_lock_irqsave(&plchan->lock, flags);
        if (!plchan->phychan && !plchan->at) {
                spin_unlock_irqrestore(&plchan->lock, flags);
                return 0;
        }

        switch (cmd) {
        case DMA_TERMINATE_ALL:
                plchan->state = PL08X_CHAN_IDLE;

                if (plchan->phychan) {
                        pl08x_stop_phy_chan(plchan->phychan);

                        /*
                         * Mark physical channel as free and free any slave
                         * signal
                         */
                        release_phy_channel(plchan);
                }
                /* Dequeue jobs and free LLIs */
                if (plchan->at) {
                        pl08x_free_txd(pl08x, plchan->at);
                        plchan->at = NULL;
                }
                /* Dequeue jobs not yet fired as well */
                pl08x_free_txd_list(pl08x, plchan);
                break;
        case DMA_PAUSE:
                pl08x_pause_phy_chan(plchan->phychan);
                plchan->state = PL08X_CHAN_PAUSED;
                break;
        case DMA_RESUME:
                pl08x_resume_phy_chan(plchan->phychan);
                plchan->state = PL08X_CHAN_RUNNING;
                break;
        default:
                /* Unknown command */
                ret = -ENXIO;
                break;
        }

        spin_unlock_irqrestore(&plchan->lock, flags);

        return ret;
}

bool pl08x_filter_id(struct dma_chan *chan, void *chan_id)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        char *name = chan_id;

        /* Check that the channel is not taken! */
        if (!strcmp(plchan->name, name))
                return true;

        return false;
}

/*
 * Just check that the device is there and active
 * TODO: turn this bit on/off depending on the number of physical channels
 * actually used, if it is zero... well shut it off. That will save some
 * power. Cut the clock at the same time.
 */
static void pl08x_ensure_on(struct pl08x_driver_data *pl08x)
{
        u32 val;

        val = readl(pl08x->base + PL080_CONFIG);
        val &= ~(PL080_CONFIG_M2_BE | PL080_CONFIG_M1_BE | PL080_CONFIG_ENABLE);
        /* We implicitly clear bit 1 and that means little-endian mode */
        val |= PL080_CONFIG_ENABLE;
        writel(val, pl08x->base + PL080_CONFIG);
}

static void pl08x_unmap_buffers(struct pl08x_txd *txd)
{
        struct device *dev = txd->tx.chan->device->dev;

        if (!(txd->tx.flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
                if (txd->tx.flags & DMA_COMPL_SRC_UNMAP_SINGLE)
                        dma_unmap_single(dev, txd->src_addr, txd->len,
                                DMA_TO_DEVICE);
                else
                        dma_unmap_page(dev, txd->src_addr, txd->len,
                                DMA_TO_DEVICE);
        }
        if (!(txd->tx.flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
                if (txd->tx.flags & DMA_COMPL_DEST_UNMAP_SINGLE)
                        dma_unmap_single(dev, txd->dst_addr, txd->len,
                                DMA_FROM_DEVICE);
                else
                        dma_unmap_page(dev, txd->dst_addr, txd->len,
                                DMA_FROM_DEVICE);
        }
}

static void pl08x_tasklet(unsigned long data)
{
        struct pl08x_dma_chan *plchan = (struct pl08x_dma_chan *) data;
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_txd *txd;
        unsigned long flags;

        spin_lock_irqsave(&plchan->lock, flags);

        txd = plchan->at;
        plchan->at = NULL;

        if (txd) {
                /* Update last completed */
                plchan->lc = txd->tx.cookie;
        }

        /* If a new descriptor is queued, set it up plchan->at is NULL here */
        if (!list_empty(&plchan->pend_list)) {
                struct pl08x_txd *next;

                next = list_first_entry(&plchan->pend_list,
                                        struct pl08x_txd,
                                        node);
                list_del(&next->node);

                pl08x_start_txd(plchan, next);
        } else if (plchan->phychan_hold) {
                /*
                 * This channel is still in use - we have a new txd being
                 * prepared and will soon be queued.  Don't give up the
                 * physical channel.
                 */
        } else {
                struct pl08x_dma_chan *waiting = NULL;

                /*
                 * No more jobs, so free up the physical channel
                 * Free any allocated signal on slave transfers too
                 */
                release_phy_channel(plchan);
                plchan->state = PL08X_CHAN_IDLE;

                /*
                 * And NOW before anyone else can grab that free:d up
                 * physical channel, see if there is some memcpy pending
                 * that seriously needs to start because of being stacked
                 * up while we were choking the physical channels with data.
                 */
                list_for_each_entry(waiting, &pl08x->memcpy.channels,
                                    chan.device_node) {
                  if (waiting->state == PL08X_CHAN_WAITING &&
                            waiting->waiting != NULL) {
                                int ret;

                                /* This should REALLY not fail now */
                                ret = prep_phy_channel(waiting,
                                                       waiting->waiting);
                                BUG_ON(ret);
                                waiting->phychan_hold--;
                                waiting->state = PL08X_CHAN_RUNNING;
                                waiting->waiting = NULL;
                                pl08x_issue_pending(&waiting->chan);
                                break;
                        }
                }
        }

        spin_unlock_irqrestore(&plchan->lock, flags);

        if (txd) {
                dma_async_tx_callback callback = txd->tx.callback;
                void *callback_param = txd->tx.callback_param;

                /* Don't try to unmap buffers on slave channels */
                if (!plchan->slave)
                        pl08x_unmap_buffers(txd);

                /* Free the descriptor */
                spin_lock_irqsave(&plchan->lock, flags);
                pl08x_free_txd(pl08x, txd);
                spin_unlock_irqrestore(&plchan->lock, flags);

                /* Callback to signal completion */
                if (callback)
                        callback(callback_param);
        }
}

static irqreturn_t pl08x_irq(int irq, void *dev)
{
        struct pl08x_driver_data *pl08x = dev;
        u32 mask = 0;
        u32 val;
        int i;

        val = readl(pl08x->base + PL080_ERR_STATUS);
        if (val) {
                /* An error interrupt (on one or more channels) */
                dev_err(&pl08x->adev->dev,
                        "%s error interrupt, register value 0x%08x\n",
                                __func__, val);
                /*
                 * Simply clear ALL PL08X error interrupts,
                 * regardless of channel and cause
                 * FIXME: should be 0x00000003 on PL081 really.
                 */
                writel(0x000000FF, pl08x->base + PL080_ERR_CLEAR);
        }
        val = readl(pl08x->base + PL080_INT_STATUS);
        for (i = 0; i < pl08x->vd->channels; i++) {
                if ((1 << i) & val) {
                        /* Locate physical channel */
                        struct pl08x_phy_chan *phychan = &pl08x->phy_chans[i];
                        struct pl08x_dma_chan *plchan = phychan->serving;

                        /* Schedule tasklet on this channel */
                        tasklet_schedule(&plchan->tasklet);

                        mask |= (1 << i);
                }
        }
        /* Clear only the terminal interrupts on channels we processed */
        writel(mask, pl08x->base + PL080_TC_CLEAR);

        return mask ? IRQ_HANDLED : IRQ_NONE;
}

/*
 * Initialise the DMAC memcpy/slave channels.
 * Make a local wrapper to hold required data
 */
static int pl08x_dma_init_virtual_channels(struct pl08x_driver_data *pl08x,
                                           struct dma_device *dmadev,
                                           unsigned int channels,
                                           bool slave)
{
        struct pl08x_dma_chan *chan;
        int i;

        INIT_LIST_HEAD(&dmadev->channels);

        /*
         * Register as many many memcpy as we have physical channels,
         * we won't always be able to use all but the code will have
         * to cope with that situation.
         */
        for (i = 0; i < channels; i++) {
                chan = kzalloc(sizeof(struct pl08x_dma_chan), GFP_KERNEL);
                if (!chan) {
                        dev_err(&pl08x->adev->dev,
                                "%s no memory for channel\n", __func__);
                        return -ENOMEM;
                }

                chan->host = pl08x;
                chan->state = PL08X_CHAN_IDLE;

                if (slave) {
                        chan->slave = true;
                        chan->name = pl08x->pd->slave_channels[i].bus_id;
                        chan->cd = &pl08x->pd->slave_channels[i];
                } else {
                        chan->cd = &pl08x->pd->memcpy_channel;
                        chan->name = kasprintf(GFP_KERNEL, "memcpy%d", i);
                        if (!chan->name) {
                                kfree(chan);
                                return -ENOMEM;
                        }
                }
                if (chan->cd->circular_buffer) {
                        dev_err(&pl08x->adev->dev,
                                "channel %s: circular buffers not supported\n",
                                chan->name);
                        kfree(chan);
                        continue;
                }
                dev_info(&pl08x->adev->dev,
                         "initialize virtual channel \"%s\"\n",
                         chan->name);

                chan->chan.device = dmadev;
                chan->chan.cookie = 0;
                chan->lc = 0;

                spin_lock_init(&chan->lock);
                INIT_LIST_HEAD(&chan->pend_list);
                tasklet_init(&chan->tasklet, pl08x_tasklet,
                             (unsigned long) chan);

                list_add_tail(&chan->chan.device_node, &dmadev->channels);
        }
        dev_info(&pl08x->adev->dev, "initialized %d virtual %s channels\n",
                 i, slave ? "slave" : "memcpy");
        return i;
}

static void pl08x_free_virtual_channels(struct dma_device *dmadev)
{
        struct pl08x_dma_chan *chan = NULL;
        struct pl08x_dma_chan *next;

        list_for_each_entry_safe(chan,
                                 next, &dmadev->channels, chan.device_node) {
                list_del(&chan->chan.device_node);
                kfree(chan);
        }
}

#ifdef CONFIG_DEBUG_FS
static const char *pl08x_state_str(enum pl08x_dma_chan_state state)
{
        switch (state) {
        case PL08X_CHAN_IDLE:
                return "idle";
        case PL08X_CHAN_RUNNING:
                return "running";
        case PL08X_CHAN_PAUSED:
                return "paused";
        case PL08X_CHAN_WAITING:
                return "waiting";
        default:
                break;
        }
        return "UNKNOWN STATE";
}

static int pl08x_debugfs_show(struct seq_file *s, void *data)
{
        struct pl08x_driver_data *pl08x = s->private;
        struct pl08x_dma_chan *chan;
        struct pl08x_phy_chan *ch;
        unsigned long flags;
        int i;

        seq_printf(s, "PL08x physical channels:\n");
        seq_printf(s, "CHANNEL:\tUSER:\n");
        seq_printf(s, "--------\t-----\n");
        for (i = 0; i < pl08x->vd->channels; i++) {
                struct pl08x_dma_chan *virt_chan;

                ch = &pl08x->phy_chans[i];

                spin_lock_irqsave(&ch->lock, flags);
                virt_chan = ch->serving;

                seq_printf(s, "%d\t\t%s\n",
                           ch->id, virt_chan ? virt_chan->name : "(none)");

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

        seq_printf(s, "\nPL08x virtual memcpy channels:\n");
        seq_printf(s, "CHANNEL:\tSTATE:\n");
        seq_printf(s, "--------\t------\n");
        list_for_each_entry(chan, &pl08x->memcpy.channels, chan.device_node) {
                seq_printf(s, "%s\t\t%s\n", chan->name,
                           pl08x_state_str(chan->state));
        }

        seq_printf(s, "\nPL08x virtual slave channels:\n");
        seq_printf(s, "CHANNEL:\tSTATE:\n");
        seq_printf(s, "--------\t------\n");
        list_for_each_entry(chan, &pl08x->slave.channels, chan.device_node) {
                seq_printf(s, "%s\t\t%s\n", chan->name,
                           pl08x_state_str(chan->state));
        }

        return 0;
}

static int pl08x_debugfs_open(struct inode *inode, struct file *file)
{
        return single_open(file, pl08x_debugfs_show, inode->i_private);
}

static const struct file_operations pl08x_debugfs_operations = {
        .open           = pl08x_debugfs_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void init_pl08x_debugfs(struct pl08x_driver_data *pl08x)
{
        /* Expose a simple debugfs interface to view all clocks */
        (void) debugfs_create_file(dev_name(&pl08x->adev->dev), S_IFREG | S_IRUGO,
                                   NULL, pl08x,
                                   &pl08x_debugfs_operations);
}

#else
static inline void init_pl08x_debugfs(struct pl08x_driver_data *pl08x)
{
}
#endif

static int pl08x_probe(struct amba_device *adev, struct amba_id *id)
{
        struct pl08x_driver_data *pl08x;
        const struct vendor_data *vd = id->data;
        int ret = 0;
        int i;

        ret = amba_request_regions(adev, NULL);
        if (ret)
                return ret;

        /* Create the driver state holder */
        pl08x = kzalloc(sizeof(struct pl08x_driver_data), GFP_KERNEL);
        if (!pl08x) {
                ret = -ENOMEM;
                goto out_no_pl08x;
        }

        /* Initialize memcpy engine */
        dma_cap_set(DMA_MEMCPY, pl08x->memcpy.cap_mask);
        pl08x->memcpy.dev = &adev->dev;
        pl08x->memcpy.device_alloc_chan_resources = pl08x_alloc_chan_resources;
        pl08x->memcpy.device_free_chan_resources = pl08x_free_chan_resources;
        pl08x->memcpy.device_prep_dma_memcpy = pl08x_prep_dma_memcpy;
        pl08x->memcpy.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
        pl08x->memcpy.device_tx_status = pl08x_dma_tx_status;
        pl08x->memcpy.device_issue_pending = pl08x_issue_pending;
        pl08x->memcpy.device_control = pl08x_control;

        /* Initialize slave engine */
        dma_cap_set(DMA_SLAVE, pl08x->slave.cap_mask);
        pl08x->slave.dev = &adev->dev;
        pl08x->slave.device_alloc_chan_resources = pl08x_alloc_chan_resources;
        pl08x->slave.device_free_chan_resources = pl08x_free_chan_resources;
        pl08x->slave.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
        pl08x->slave.device_tx_status = pl08x_dma_tx_status;
        pl08x->slave.device_issue_pending = pl08x_issue_pending;
        pl08x->slave.device_prep_slave_sg = pl08x_prep_slave_sg;
        pl08x->slave.device_control = pl08x_control;

        /* Get the platform data */
        pl08x->pd = dev_get_platdata(&adev->dev);
        if (!pl08x->pd) {
                dev_err(&adev->dev, "no platform data supplied\n");
                goto out_no_platdata;
        }

        /* Assign useful pointers to the driver state */
        pl08x->adev = adev;
        pl08x->vd = vd;

        /* By default, AHB1 only.  If dualmaster, from platform */
        pl08x->lli_buses = PL08X_AHB1;
        pl08x->mem_buses = PL08X_AHB1;
        if (pl08x->vd->dualmaster) {
                pl08x->lli_buses = pl08x->pd->lli_buses;
                pl08x->mem_buses = pl08x->pd->mem_buses;
        }

        /* A DMA memory pool for LLIs, align on 1-byte boundary */
        pl08x->pool = dma_pool_create(DRIVER_NAME, &pl08x->adev->dev,
                        PL08X_LLI_TSFR_SIZE, PL08X_ALIGN, 0);
        if (!pl08x->pool) {
                ret = -ENOMEM;
                goto out_no_lli_pool;
        }

        spin_lock_init(&pl08x->lock);

        pl08x->base = ioremap(adev->res.start, resource_size(&adev->res));
        if (!pl08x->base) {
                ret = -ENOMEM;
                goto out_no_ioremap;
        }

        /* Turn on the PL08x */
        pl08x_ensure_on(pl08x);

        /* Attach the interrupt handler */
        writel(0x000000FF, pl08x->base + PL080_ERR_CLEAR);
        writel(0x000000FF, pl08x->base + PL080_TC_CLEAR);

        ret = request_irq(adev->irq[0], pl08x_irq, IRQF_DISABLED,
                          DRIVER_NAME, pl08x);
        if (ret) {
                dev_err(&adev->dev, "%s failed to request interrupt %d\n",
                        __func__, adev->irq[0]);
                goto out_no_irq;
        }

        /* Initialize physical channels */
        pl08x->phy_chans = kmalloc((vd->channels * sizeof(struct pl08x_phy_chan)),
                        GFP_KERNEL);
        if (!pl08x->phy_chans) {
                dev_err(&adev->dev, "%s failed to allocate "
                        "physical channel holders\n",
                        __func__);
                goto out_no_phychans;
        }

        for (i = 0; i < vd->channels; i++) {
                struct pl08x_phy_chan *ch = &pl08x->phy_chans[i];

                ch->id = i;
                ch->base = pl08x->base + PL080_Cx_BASE(i);
                spin_lock_init(&ch->lock);
                ch->serving = NULL;
                ch->signal = -1;
                dev_info(&adev->dev,
                         "physical channel %d is %s\n", i,
                         pl08x_phy_channel_busy(ch) ? "BUSY" : "FREE");
        }

        /* Register as many memcpy channels as there are physical channels */
        ret = pl08x_dma_init_virtual_channels(pl08x, &pl08x->memcpy,
                                              pl08x->vd->channels, false);
        if (ret <= 0) {
                dev_warn(&pl08x->adev->dev,
                         "%s failed to enumerate memcpy channels - %d\n",
                         __func__, ret);
                goto out_no_memcpy;
        }
        pl08x->memcpy.chancnt = ret;

        /* Register slave channels */
        ret = pl08x_dma_init_virtual_channels(pl08x, &pl08x->slave,
                                              pl08x->pd->num_slave_channels,
                                              true);
        if (ret <= 0) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to enumerate slave channels - %d\n",
                                __func__, ret);
                goto out_no_slave;
        }
        pl08x->slave.chancnt = ret;

        ret = dma_async_device_register(&pl08x->memcpy);
        if (ret) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to register memcpy as an async device - %d\n",
                        __func__, ret);
                goto out_no_memcpy_reg;
        }

        ret = dma_async_device_register(&pl08x->slave);
        if (ret) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to register slave as an async device - %d\n",
                        __func__, ret);
                goto out_no_slave_reg;
        }

        amba_set_drvdata(adev, pl08x);
        init_pl08x_debugfs(pl08x);
        dev_info(&pl08x->adev->dev, "DMA: PL%03x rev%u at 0x%08llx irq %d\n",
                 amba_part(adev), amba_rev(adev),
                 (unsigned long long)adev->res.start, adev->irq[0]);
        return 0;

out_no_slave_reg:
        dma_async_device_unregister(&pl08x->memcpy);
out_no_memcpy_reg:
        pl08x_free_virtual_channels(&pl08x->slave);
out_no_slave:
        pl08x_free_virtual_channels(&pl08x->memcpy);
out_no_memcpy:
        kfree(pl08x->phy_chans);
out_no_phychans:
        free_irq(adev->irq[0], pl08x);
out_no_irq:
        iounmap(pl08x->base);
out_no_ioremap:
        dma_pool_destroy(pl08x->pool);
out_no_lli_pool:
out_no_platdata:
        kfree(pl08x);
out_no_pl08x:
        amba_release_regions(adev);
        return ret;
}

/* PL080 has 8 channels and the PL080 have just 2 */
static struct vendor_data vendor_pl080 = {
        .channels = 8,
        .dualmaster = true,
};

static struct vendor_data vendor_pl081 = {
        .channels = 2,
        .dualmaster = false,
};

static struct amba_id pl08x_ids[] = {
        /* PL080 */
        {
                .id     = 0x00041080,
                .mask   = 0x000fffff,
                .data   = &vendor_pl080,
        },
        /* PL081 */
        {
                .id     = 0x00041081,
                .mask   = 0x000fffff,
                .data   = &vendor_pl081,
        },
        /* Nomadik 8815 PL080 variant */
        {
                .id     = 0x00280880,
                .mask   = 0x00ffffff,
                .data   = &vendor_pl080,
        },
        { 0, 0 },
};

static struct amba_driver pl08x_amba_driver = {
        .drv.name       = DRIVER_NAME,
        .id_table       = pl08x_ids,
        .probe          = pl08x_probe,
};

static int __init pl08x_init(void)
{
        int retval;
        retval = amba_driver_register(&pl08x_amba_driver);
        if (retval)
                printk(KERN_WARNING DRIVER_NAME
                       "failed to register as an AMBA device (%d)\n",
                       retval);
        return retval;
}
subsys_initcall(pl08x_init);