/*
 * Copyright 2015 Robert Jarzmik <robert.jarzmik@free.fr>
 *
 * 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/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/dmaengine.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/platform_data/mmp_dma.h>
#include <linux/dmapool.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/of.h>
#include <linux/wait.h>
#include <linux/dma/pxa-dma.h>

#include "dmaengine.h"
#include "virt-dma.h"

#define DCSR(n)         (0x0000 + ((n) << 2))
#define DALGN(n)        0x00a0
#define DINT            0x00f0
#define DDADR(n)        (0x0200 + ((n) << 4))
#define DSADR(n)        (0x0204 + ((n) << 4))
#define DTADR(n)        (0x0208 + ((n) << 4))
#define DCMD(n)         (0x020c + ((n) << 4))

#define PXA_DCSR_RUN            BIT(31) /* Run Bit (read / write) */
#define PXA_DCSR_NODESC         BIT(30) /* No-Descriptor Fetch (read / write) */
#define PXA_DCSR_STOPIRQEN      BIT(29) /* Stop Interrupt Enable (R/W) */
#define PXA_DCSR_REQPEND        BIT(8)  /* Request Pending (read-only) */
#define PXA_DCSR_STOPSTATE      BIT(3)  /* Stop State (read-only) */
#define PXA_DCSR_ENDINTR        BIT(2)  /* End Interrupt (read / write) */
#define PXA_DCSR_STARTINTR      BIT(1)  /* Start Interrupt (read / write) */
#define PXA_DCSR_BUSERR         BIT(0)  /* Bus Error Interrupt (read / write) */

#define PXA_DCSR_EORIRQEN       BIT(28) /* End of Receive IRQ Enable (R/W) */
#define PXA_DCSR_EORJMPEN       BIT(27) /* Jump to next descriptor on EOR */
#define PXA_DCSR_EORSTOPEN      BIT(26) /* STOP on an EOR */
#define PXA_DCSR_SETCMPST       BIT(25) /* Set Descriptor Compare Status */
#define PXA_DCSR_CLRCMPST       BIT(24) /* Clear Descriptor Compare Status */
#define PXA_DCSR_CMPST          BIT(10) /* The Descriptor Compare Status */
#define PXA_DCSR_EORINTR        BIT(9)  /* The end of Receive */

#define DRCMR_MAPVLD    BIT(7)  /* Map Valid (read / write) */
#define DRCMR_CHLNUM    0x1f    /* mask for Channel Number (read / write) */

#define DDADR_DESCADDR  0xfffffff0      /* Address of next descriptor (mask) */
#define DDADR_STOP      BIT(0)  /* Stop (read / write) */

#define PXA_DCMD_INCSRCADDR     BIT(31) /* Source Address Increment Setting. */
#define PXA_DCMD_INCTRGADDR     BIT(30) /* Target Address Increment Setting. */
#define PXA_DCMD_FLOWSRC        BIT(29) /* Flow Control by the source. */
#define PXA_DCMD_FLOWTRG        BIT(28) /* Flow Control by the target. */
#define PXA_DCMD_STARTIRQEN     BIT(22) /* Start Interrupt Enable */
#define PXA_DCMD_ENDIRQEN       BIT(21) /* End Interrupt Enable */
#define PXA_DCMD_ENDIAN         BIT(18) /* Device Endian-ness. */
#define PXA_DCMD_BURST8         (1 << 16)       /* 8 byte burst */
#define PXA_DCMD_BURST16        (2 << 16)       /* 16 byte burst */
#define PXA_DCMD_BURST32        (3 << 16)       /* 32 byte burst */
#define PXA_DCMD_WIDTH1         (1 << 14)       /* 1 byte width */
#define PXA_DCMD_WIDTH2         (2 << 14)       /* 2 byte width (HalfWord) */
#define PXA_DCMD_WIDTH4         (3 << 14)       /* 4 byte width (Word) */
#define PXA_DCMD_LENGTH         0x01fff         /* length mask (max = 8K - 1) */

#define PDMA_ALIGNMENT          3
#define PDMA_MAX_DESC_BYTES     (PXA_DCMD_LENGTH & ~((1 << PDMA_ALIGNMENT) - 1))

struct pxad_desc_hw {
        u32 ddadr;      /* Points to the next descriptor + flags */
        u32 dsadr;      /* DSADR value for the current transfer */
        u32 dtadr;      /* DTADR value for the current transfer */
        u32 dcmd;       /* DCMD value for the current transfer */
} __aligned(16);

struct pxad_desc_sw {
        struct virt_dma_desc    vd;             /* Virtual descriptor */
        int                     nb_desc;        /* Number of hw. descriptors */
        size_t                  len;            /* Number of bytes xfered */
        dma_addr_t              first;          /* First descriptor's addr */

        /* At least one descriptor has an src/dst address not multiple of 8 */
        bool                    misaligned;
        bool                    cyclic;
        struct dma_pool         *desc_pool;     /* Channel's used allocator */

        struct pxad_desc_hw     *hw_desc[];     /* DMA coherent descriptors */
};

struct pxad_phy {
        int                     idx;
        void __iomem            *base;
        struct pxad_chan        *vchan;
};

struct pxad_chan {
        struct virt_dma_chan    vc;             /* Virtual channel */
        u32                     drcmr;          /* Requestor of the channel */
        enum pxad_chan_prio     prio;           /* Required priority of phy */
        /*
         * At least one desc_sw in submitted or issued transfers on this channel
         * has one address such as: addr % 8 != 0. This implies the DALGN
         * setting on the phy.
         */
        bool                    misaligned;
        struct dma_slave_config cfg;            /* Runtime config */

        /* protected by vc->lock */
        struct pxad_phy         *phy;
        struct dma_pool         *desc_pool;     /* Descriptors pool */
        dma_cookie_t            bus_error;

        wait_queue_head_t       wq_state;
};

struct pxad_device {
        struct dma_device               slave;
        int                             nr_chans;
        int                             nr_requestors;
        void __iomem                    *base;
        struct pxad_phy                 *phys;
        spinlock_t                      phy_lock;       /* Phy association */
#ifdef CONFIG_DEBUG_FS
        struct dentry                   *dbgfs_root;
        struct dentry                   *dbgfs_state;
        struct dentry                   **dbgfs_chan;
#endif
};

#define tx_to_pxad_desc(tx)                                     \
        container_of(tx, struct pxad_desc_sw, async_tx)
#define to_pxad_chan(dchan)                                     \
        container_of(dchan, struct pxad_chan, vc.chan)
#define to_pxad_dev(dmadev)                                     \
        container_of(dmadev, struct pxad_device, slave)
#define to_pxad_sw_desc(_vd)                            \
        container_of((_vd), struct pxad_desc_sw, vd)

#define _phy_readl_relaxed(phy, _reg)                                   \
        readl_relaxed((phy)->base + _reg((phy)->idx))
#define phy_readl_relaxed(phy, _reg)                                    \
        ({                                                              \
                u32 _v;                                                 \
                _v = readl_relaxed((phy)->base + _reg((phy)->idx));     \
                dev_vdbg(&phy->vchan->vc.chan.dev->device,              \
                         "%s(): readl(%s): 0x%08x\n", __func__, #_reg,  \
                          _v);                                          \
                _v;                                                     \
        })
#define phy_writel(phy, val, _reg)                                      \
        do {                                                            \
                writel((val), (phy)->base + _reg((phy)->idx));          \
                dev_vdbg(&phy->vchan->vc.chan.dev->device,              \
                         "%s(): writel(0x%08x, %s)\n",                  \
                         __func__, (u32)(val), #_reg);                  \
        } while (0)
#define phy_writel_relaxed(phy, val, _reg)                              \
        do {                                                            \
                writel_relaxed((val), (phy)->base + _reg((phy)->idx));  \
                dev_vdbg(&phy->vchan->vc.chan.dev->device,              \
                         "%s(): writel_relaxed(0x%08x, %s)\n",          \
                         __func__, (u32)(val), #_reg);                  \
        } while (0)

static unsigned int pxad_drcmr(unsigned int line)
{
        if (line < 64)
                return 0x100 + line * 4;
        return 0x1000 + line * 4;
}

static bool pxad_filter_fn(struct dma_chan *chan, void *param);

/*
 * Debug fs
 */
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>

static int requester_chan_show(struct seq_file *s, void *p)
{
        struct pxad_phy *phy = s->private;
        int i;
        u32 drcmr;

        seq_printf(s, "DMA channel %d requester :\n", phy->idx);
        for (i = 0; i < 70; i++) {
                drcmr = readl_relaxed(phy->base + pxad_drcmr(i));
                if ((drcmr & DRCMR_CHLNUM) == phy->idx)
                        seq_printf(s, "\tRequester %d (MAPVLD=%d)\n", i,
                                   !!(drcmr & DRCMR_MAPVLD));
        }
        return 0;
}

static inline int dbg_burst_from_dcmd(u32 dcmd)
{
        int burst = (dcmd >> 16) & 0x3;

        return burst ? 4 << burst : 0;
}

static int is_phys_valid(unsigned long addr)
{
        return pfn_valid(__phys_to_pfn(addr));
}

#define PXA_DCSR_STR(flag) (dcsr & PXA_DCSR_##flag ? #flag" " : "")
#define PXA_DCMD_STR(flag) (dcmd & PXA_DCMD_##flag ? #flag" " : "")

static int descriptors_show(struct seq_file *s, void *p)
{
        struct pxad_phy *phy = s->private;
        int i, max_show = 20, burst, width;
        u32 dcmd;
        unsigned long phys_desc, ddadr;
        struct pxad_desc_hw *desc;

        phys_desc = ddadr = _phy_readl_relaxed(phy, DDADR);

        seq_printf(s, "DMA channel %d descriptors :\n", phy->idx);
        seq_printf(s, "[%03d] First descriptor unknown\n", 0);
        for (i = 1; i < max_show && is_phys_valid(phys_desc); i++) {
                desc = phys_to_virt(phys_desc);
                dcmd = desc->dcmd;
                burst = dbg_burst_from_dcmd(dcmd);
                width = (1 << ((dcmd >> 14) & 0x3)) >> 1;

                seq_printf(s, "[%03d] Desc at %08lx(virt %p)\n",
                           i, phys_desc, desc);
                seq_printf(s, "\tDDADR = %08x\n", desc->ddadr);
                seq_printf(s, "\tDSADR = %08x\n", desc->dsadr);
                seq_printf(s, "\tDTADR = %08x\n", desc->dtadr);
                seq_printf(s, "\tDCMD  = %08x (%s%s%s%s%s%s%sburst=%d width=%d len=%d)\n",
                           dcmd,
                           PXA_DCMD_STR(INCSRCADDR), PXA_DCMD_STR(INCTRGADDR),
                           PXA_DCMD_STR(FLOWSRC), PXA_DCMD_STR(FLOWTRG),
                           PXA_DCMD_STR(STARTIRQEN), PXA_DCMD_STR(ENDIRQEN),
                           PXA_DCMD_STR(ENDIAN), burst, width,
                           dcmd & PXA_DCMD_LENGTH);
                phys_desc = desc->ddadr;
        }
        if (i == max_show)
                seq_printf(s, "[%03d] Desc at %08lx ... max display reached\n",
                           i, phys_desc);
        else
                seq_printf(s, "[%03d] Desc at %08lx is %s\n",
                           i, phys_desc, phys_desc == DDADR_STOP ?
                           "DDADR_STOP" : "invalid");

        return 0;
}

static int chan_state_show(struct seq_file *s, void *p)
{
        struct pxad_phy *phy = s->private;
        u32 dcsr, dcmd;
        int burst, width;
        static const char * const str_prio[] = {
                "high", "normal", "low", "invalid"
        };

        dcsr = _phy_readl_relaxed(phy, DCSR);
        dcmd = _phy_readl_relaxed(phy, DCMD);
        burst = dbg_burst_from_dcmd(dcmd);
        width = (1 << ((dcmd >> 14) & 0x3)) >> 1;

        seq_printf(s, "DMA channel %d\n", phy->idx);
        seq_printf(s, "\tPriority : %s\n",
                          str_prio[(phy->idx & 0xf) / 4]);
        seq_printf(s, "\tUnaligned transfer bit: %s\n",
                          _phy_readl_relaxed(phy, DALGN) & BIT(phy->idx) ?
                          "yes" : "no");
        seq_printf(s, "\tDCSR  = %08x (%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s)\n",
                   dcsr, PXA_DCSR_STR(RUN), PXA_DCSR_STR(NODESC),
                   PXA_DCSR_STR(STOPIRQEN), PXA_DCSR_STR(EORIRQEN),
                   PXA_DCSR_STR(EORJMPEN), PXA_DCSR_STR(EORSTOPEN),
                   PXA_DCSR_STR(SETCMPST), PXA_DCSR_STR(CLRCMPST),
                   PXA_DCSR_STR(CMPST), PXA_DCSR_STR(EORINTR),
                   PXA_DCSR_STR(REQPEND), PXA_DCSR_STR(STOPSTATE),
                   PXA_DCSR_STR(ENDINTR), PXA_DCSR_STR(STARTINTR),
                   PXA_DCSR_STR(BUSERR));

        seq_printf(s, "\tDCMD  = %08x (%s%s%s%s%s%s%sburst=%d width=%d len=%d)\n",
                   dcmd,
                   PXA_DCMD_STR(INCSRCADDR), PXA_DCMD_STR(INCTRGADDR),
                   PXA_DCMD_STR(FLOWSRC), PXA_DCMD_STR(FLOWTRG),
                   PXA_DCMD_STR(STARTIRQEN), PXA_DCMD_STR(ENDIRQEN),
                   PXA_DCMD_STR(ENDIAN), burst, width, dcmd & PXA_DCMD_LENGTH);
        seq_printf(s, "\tDSADR = %08x\n", _phy_readl_relaxed(phy, DSADR));
        seq_printf(s, "\tDTADR = %08x\n", _phy_readl_relaxed(phy, DTADR));
        seq_printf(s, "\tDDADR = %08x\n", _phy_readl_relaxed(phy, DDADR));

        return 0;
}

static int state_show(struct seq_file *s, void *p)
{
        struct pxad_device *pdev = s->private;

        /* basic device status */
        seq_puts(s, "DMA engine status\n");
        seq_printf(s, "\tChannel number: %d\n", pdev->nr_chans);

        return 0;
}

DEFINE_SHOW_ATTRIBUTE(state);
DEFINE_SHOW_ATTRIBUTE(chan_state);
DEFINE_SHOW_ATTRIBUTE(descriptors);
DEFINE_SHOW_ATTRIBUTE(requester_chan);

static struct dentry *pxad_dbg_alloc_chan(struct pxad_device *pdev,
                                             int ch, struct dentry *chandir)
{
        char chan_name[11];
        struct dentry *chan, *chan_state = NULL, *chan_descr = NULL;
        struct dentry *chan_reqs = NULL;
        void *dt;

        scnprintf(chan_name, sizeof(chan_name), "%d", ch);
        chan = debugfs_create_dir(chan_name, chandir);
        dt = (void *)&pdev->phys[ch];

        if (chan)
                chan_state = debugfs_create_file("state", 0400, chan, dt,
                                                 &chan_state_fops);
        if (chan_state)
                chan_descr = debugfs_create_file("descriptors", 0400, chan, dt,
                                                 &descriptors_fops);
        if (chan_descr)
                chan_reqs = debugfs_create_file("requesters", 0400, chan, dt,
                                                &requester_chan_fops);
        if (!chan_reqs)
                goto err_state;

        return chan;

err_state:
        debugfs_remove_recursive(chan);
        return NULL;
}

static void pxad_init_debugfs(struct pxad_device *pdev)
{
        int i;
        struct dentry *chandir;

        pdev->dbgfs_root = debugfs_create_dir(dev_name(pdev->slave.dev), NULL);
        if (IS_ERR(pdev->dbgfs_root) || !pdev->dbgfs_root)
                goto err_root;

        pdev->dbgfs_state = debugfs_create_file("state", 0400, pdev->dbgfs_root,
                                                pdev, &state_fops);
        if (!pdev->dbgfs_state)
                goto err_state;

        pdev->dbgfs_chan =
                kmalloc_array(pdev->nr_chans, sizeof(*pdev->dbgfs_state),
                              GFP_KERNEL);
        if (!pdev->dbgfs_chan)
                goto err_alloc;

        chandir = debugfs_create_dir("channels", pdev->dbgfs_root);
        if (!chandir)
                goto err_chandir;

        for (i = 0; i < pdev->nr_chans; i++) {
                pdev->dbgfs_chan[i] = pxad_dbg_alloc_chan(pdev, i, chandir);
                if (!pdev->dbgfs_chan[i])
                        goto err_chans;
        }

        return;
err_chans:
err_chandir:
        kfree(pdev->dbgfs_chan);
err_alloc:
err_state:
        debugfs_remove_recursive(pdev->dbgfs_root);
err_root:
        pr_err("pxad: debugfs is not available\n");
}

static void pxad_cleanup_debugfs(struct pxad_device *pdev)
{
        debugfs_remove_recursive(pdev->dbgfs_root);
}
#else
static inline void pxad_init_debugfs(struct pxad_device *pdev) {}
static inline void pxad_cleanup_debugfs(struct pxad_device *pdev) {}
#endif

static struct pxad_phy *lookup_phy(struct pxad_chan *pchan)
{
        int prio, i;
        struct pxad_device *pdev = to_pxad_dev(pchan->vc.chan.device);
        struct pxad_phy *phy, *found = NULL;
        unsigned long flags;

        /*
         * dma channel priorities
         * ch 0 - 3,  16 - 19  <--> (0)
         * ch 4 - 7,  20 - 23  <--> (1)
         * ch 8 - 11, 24 - 27  <--> (2)
         * ch 12 - 15, 28 - 31  <--> (3)
         */

        spin_lock_irqsave(&pdev->phy_lock, flags);
        for (prio = pchan->prio; prio >= PXAD_PRIO_HIGHEST; prio--) {
                for (i = 0; i < pdev->nr_chans; i++) {
                        if (prio != (i & 0xf) >> 2)
                                continue;
                        phy = &pdev->phys[i];
                        if (!phy->vchan) {
                                phy->vchan = pchan;
                                found = phy;
                                goto out_unlock;
                        }
                }
        }

out_unlock:
        spin_unlock_irqrestore(&pdev->phy_lock, flags);
        dev_dbg(&pchan->vc.chan.dev->device,
                "%s(): phy=%p(%d)\n", __func__, found,
                found ? found->idx : -1);

        return found;
}

static void pxad_free_phy(struct pxad_chan *chan)
{
        struct pxad_device *pdev = to_pxad_dev(chan->vc.chan.device);
        unsigned long flags;
        u32 reg;

        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): freeing\n", __func__);
        if (!chan->phy)
                return;

        /* clear the channel mapping in DRCMR */
        if (chan->drcmr <= pdev->nr_requestors) {
                reg = pxad_drcmr(chan->drcmr);
                writel_relaxed(0, chan->phy->base + reg);
        }

        spin_lock_irqsave(&pdev->phy_lock, flags);
        chan->phy->vchan = NULL;
        chan->phy = NULL;
        spin_unlock_irqrestore(&pdev->phy_lock, flags);
}

static bool is_chan_running(struct pxad_chan *chan)
{
        u32 dcsr;
        struct pxad_phy *phy = chan->phy;

        if (!phy)
                return false;
        dcsr = phy_readl_relaxed(phy, DCSR);
        return dcsr & PXA_DCSR_RUN;
}

static bool is_running_chan_misaligned(struct pxad_chan *chan)
{
        u32 dalgn;

        BUG_ON(!chan->phy);
        dalgn = phy_readl_relaxed(chan->phy, DALGN);
        return dalgn & (BIT(chan->phy->idx));
}

static void phy_enable(struct pxad_phy *phy, bool misaligned)
{
        struct pxad_device *pdev;
        u32 reg, dalgn;

        if (!phy->vchan)
                return;

        dev_dbg(&phy->vchan->vc.chan.dev->device,
                "%s(); phy=%p(%d) misaligned=%d\n", __func__,
                phy, phy->idx, misaligned);

        pdev = to_pxad_dev(phy->vchan->vc.chan.device);
        if (phy->vchan->drcmr <= pdev->nr_requestors) {
                reg = pxad_drcmr(phy->vchan->drcmr);
                writel_relaxed(DRCMR_MAPVLD | phy->idx, phy->base + reg);
        }

        dalgn = phy_readl_relaxed(phy, DALGN);
        if (misaligned)
                dalgn |= BIT(phy->idx);
        else
                dalgn &= ~BIT(phy->idx);
        phy_writel_relaxed(phy, dalgn, DALGN);

        phy_writel(phy, PXA_DCSR_STOPIRQEN | PXA_DCSR_ENDINTR |
                   PXA_DCSR_BUSERR | PXA_DCSR_RUN, DCSR);
}

static void phy_disable(struct pxad_phy *phy)
{
        u32 dcsr;

        if (!phy)
                return;

        dcsr = phy_readl_relaxed(phy, DCSR);
        dev_dbg(&phy->vchan->vc.chan.dev->device,
                "%s(): phy=%p(%d)\n", __func__, phy, phy->idx);
        phy_writel(phy, dcsr & ~PXA_DCSR_RUN & ~PXA_DCSR_STOPIRQEN, DCSR);
}

static void pxad_launch_chan(struct pxad_chan *chan,
                                 struct pxad_desc_sw *desc)
{
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): desc=%p\n", __func__, desc);
        if (!chan->phy) {
                chan->phy = lookup_phy(chan);
                if (!chan->phy) {
                        dev_dbg(&chan->vc.chan.dev->device,
                                "%s(): no free dma channel\n", __func__);
                        return;
                }
        }
        chan->bus_error = 0;

        /*
         * Program the descriptor's address into the DMA controller,
         * then start the DMA transaction
         */
        phy_writel(chan->phy, desc->first, DDADR);
        phy_enable(chan->phy, chan->misaligned);
        wake_up(&chan->wq_state);
}

static void set_updater_desc(struct pxad_desc_sw *sw_desc,
                             unsigned long flags)
{
        struct pxad_desc_hw *updater =
                sw_desc->hw_desc[sw_desc->nb_desc - 1];
        dma_addr_t dma = sw_desc->hw_desc[sw_desc->nb_desc - 2]->ddadr;

        updater->ddadr = DDADR_STOP;
        updater->dsadr = dma;
        updater->dtadr = dma + 8;
        updater->dcmd = PXA_DCMD_WIDTH4 | PXA_DCMD_BURST32 |
                (PXA_DCMD_LENGTH & sizeof(u32));
        if (flags & DMA_PREP_INTERRUPT)
                updater->dcmd |= PXA_DCMD_ENDIRQEN;
        if (sw_desc->cyclic)
                sw_desc->hw_desc[sw_desc->nb_desc - 2]->ddadr = sw_desc->first;
}

static bool is_desc_completed(struct virt_dma_desc *vd)
{
        struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);
        struct pxad_desc_hw *updater =
                sw_desc->hw_desc[sw_desc->nb_desc - 1];

        return updater->dtadr != (updater->dsadr + 8);
}

static void pxad_desc_chain(struct virt_dma_desc *vd1,
                                struct virt_dma_desc *vd2)
{
        struct pxad_desc_sw *desc1 = to_pxad_sw_desc(vd1);
        struct pxad_desc_sw *desc2 = to_pxad_sw_desc(vd2);
        dma_addr_t dma_to_chain;

        dma_to_chain = desc2->first;
        desc1->hw_desc[desc1->nb_desc - 1]->ddadr = dma_to_chain;
}

static bool pxad_try_hotchain(struct virt_dma_chan *vc,
                                  struct virt_dma_desc *vd)
{
        struct virt_dma_desc *vd_last_issued = NULL;
        struct pxad_chan *chan = to_pxad_chan(&vc->chan);

        /*
         * Attempt to hot chain the tx if the phy is still running. This is
         * considered successful only if either the channel is still running
         * after the chaining, or if the chained transfer is completed after
         * having been hot chained.
         * A change of alignment is not allowed, and forbids hotchaining.
         */
        if (is_chan_running(chan)) {
                BUG_ON(list_empty(&vc->desc_issued));

                if (!is_running_chan_misaligned(chan) &&
                    to_pxad_sw_desc(vd)->misaligned)
                        return false;

                vd_last_issued = list_entry(vc->desc_issued.prev,
                                            struct virt_dma_desc, node);
                pxad_desc_chain(vd_last_issued, vd);
                if (is_chan_running(chan) || is_desc_completed(vd))
                        return true;
        }

        return false;
}

static unsigned int clear_chan_irq(struct pxad_phy *phy)
{
        u32 dcsr;
        u32 dint = readl(phy->base + DINT);

        if (!(dint & BIT(phy->idx)))
                return PXA_DCSR_RUN;

        /* clear irq */
        dcsr = phy_readl_relaxed(phy, DCSR);
        phy_writel(phy, dcsr, DCSR);
        if ((dcsr & PXA_DCSR_BUSERR) && (phy->vchan))
                dev_warn(&phy->vchan->vc.chan.dev->device,
                         "%s(chan=%p): PXA_DCSR_BUSERR\n",
                         __func__, &phy->vchan);

        return dcsr & ~PXA_DCSR_RUN;
}

static irqreturn_t pxad_chan_handler(int irq, void *dev_id)
{
        struct pxad_phy *phy = dev_id;
        struct pxad_chan *chan = phy->vchan;
        struct virt_dma_desc *vd, *tmp;
        unsigned int dcsr;
        unsigned long flags;
        bool vd_completed;
        dma_cookie_t last_started = 0;

        BUG_ON(!chan);

        dcsr = clear_chan_irq(phy);
        if (dcsr & PXA_DCSR_RUN)
                return IRQ_NONE;

        spin_lock_irqsave(&chan->vc.lock, flags);
        list_for_each_entry_safe(vd, tmp, &chan->vc.desc_issued, node) {
                vd_completed = is_desc_completed(vd);
                dev_dbg(&chan->vc.chan.dev->device,
                        "%s(): checking txd %p[%x]: completed=%d dcsr=0x%x\n",
                        __func__, vd, vd->tx.cookie, vd_completed,
                        dcsr);
                last_started = vd->tx.cookie;
                if (to_pxad_sw_desc(vd)->cyclic) {
                        vchan_cyclic_callback(vd);
                        break;
                }
                if (vd_completed) {
                        list_del(&vd->node);
                        vchan_cookie_complete(vd);
                } else {
                        break;
                }
        }

        if (dcsr & PXA_DCSR_BUSERR) {
                chan->bus_error = last_started;
                phy_disable(phy);
        }

        if (!chan->bus_error && dcsr & PXA_DCSR_STOPSTATE) {
                dev_dbg(&chan->vc.chan.dev->device,
                "%s(): channel stopped, submitted_empty=%d issued_empty=%d",
                        __func__,
                        list_empty(&chan->vc.desc_submitted),
                        list_empty(&chan->vc.desc_issued));
                phy_writel_relaxed(phy, dcsr & ~PXA_DCSR_STOPIRQEN, DCSR);

                if (list_empty(&chan->vc.desc_issued)) {
                        chan->misaligned =
                                !list_empty(&chan->vc.desc_submitted);
                } else {
                        vd = list_first_entry(&chan->vc.desc_issued,
                                              struct virt_dma_desc, node);
                        pxad_launch_chan(chan, to_pxad_sw_desc(vd));
                }
        }
        spin_unlock_irqrestore(&chan->vc.lock, flags);
        wake_up(&chan->wq_state);

        return IRQ_HANDLED;
}

static irqreturn_t pxad_int_handler(int irq, void *dev_id)
{
        struct pxad_device *pdev = dev_id;
        struct pxad_phy *phy;
        u32 dint = readl(pdev->base + DINT);
        int i, ret = IRQ_NONE;

        while (dint) {
                i = __ffs(dint);
                dint &= (dint - 1);
                phy = &pdev->phys[i];
                if (pxad_chan_handler(irq, phy) == IRQ_HANDLED)
                        ret = IRQ_HANDLED;
        }

        return ret;
}

static int pxad_alloc_chan_resources(struct dma_chan *dchan)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct pxad_device *pdev = to_pxad_dev(chan->vc.chan.device);

        if (chan->desc_pool)
                return 1;

        chan->desc_pool = dma_pool_create(dma_chan_name(dchan),
                                          pdev->slave.dev,
                                          sizeof(struct pxad_desc_hw),
                                          __alignof__(struct pxad_desc_hw),
                                          0);
        if (!chan->desc_pool) {
                dev_err(&chan->vc.chan.dev->device,
                        "%s(): unable to allocate descriptor pool\n",
                        __func__);
                return -ENOMEM;
        }

        return 1;
}

static void pxad_free_chan_resources(struct dma_chan *dchan)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);

        vchan_free_chan_resources(&chan->vc);
        dma_pool_destroy(chan->desc_pool);
        chan->desc_pool = NULL;

        chan->drcmr = U32_MAX;
        chan->prio = PXAD_PRIO_LOWEST;
}

static void pxad_free_desc(struct virt_dma_desc *vd)
{
        int i;
        dma_addr_t dma;
        struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);

        BUG_ON(sw_desc->nb_desc == 0);
        for (i = sw_desc->nb_desc - 1; i >= 0; i--) {
                if (i > 0)
                        dma = sw_desc->hw_desc[i - 1]->ddadr;
                else
                        dma = sw_desc->first;
                dma_pool_free(sw_desc->desc_pool,
                              sw_desc->hw_desc[i], dma);
        }
        sw_desc->nb_desc = 0;
        kfree(sw_desc);
}

static struct pxad_desc_sw *
pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc)
{
        struct pxad_desc_sw *sw_desc;
        dma_addr_t dma;
        int i;

        sw_desc = kzalloc(sizeof(*sw_desc) +
                          nb_hw_desc * sizeof(struct pxad_desc_hw *),
                          GFP_NOWAIT);
        if (!sw_desc)
                return NULL;
        sw_desc->desc_pool = chan->desc_pool;

        for (i = 0; i < nb_hw_desc; i++) {
                sw_desc->hw_desc[i] = dma_pool_alloc(sw_desc->desc_pool,
                                                     GFP_NOWAIT, &dma);
                if (!sw_desc->hw_desc[i]) {
                        dev_err(&chan->vc.chan.dev->device,
                                "%s(): Couldn't allocate the %dth hw_desc from dma_pool %p\n",
                                __func__, i, sw_desc->desc_pool);
                        goto err;
                }

                if (i == 0)
                        sw_desc->first = dma;
                else
                        sw_desc->hw_desc[i - 1]->ddadr = dma;
                sw_desc->nb_desc++;
        }

        return sw_desc;
err:
        pxad_free_desc(&sw_desc->vd);
        return NULL;
}

static dma_cookie_t pxad_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct virt_dma_chan *vc = to_virt_chan(tx->chan);
        struct pxad_chan *chan = to_pxad_chan(&vc->chan);
        struct virt_dma_desc *vd_chained = NULL,
                *vd = container_of(tx, struct virt_dma_desc, tx);
        dma_cookie_t cookie;
        unsigned long flags;

        set_updater_desc(to_pxad_sw_desc(vd), tx->flags);

        spin_lock_irqsave(&vc->lock, flags);
        cookie = dma_cookie_assign(tx);

        if (list_empty(&vc->desc_submitted) && pxad_try_hotchain(vc, vd)) {
                list_move_tail(&vd->node, &vc->desc_issued);
                dev_dbg(&chan->vc.chan.dev->device,
                        "%s(): txd %p[%x]: submitted (hot linked)\n",
                        __func__, vd, cookie);
                goto out;
        }

        /*
         * Fallback to placing the tx in the submitted queue
         */
        if (!list_empty(&vc->desc_submitted)) {
                vd_chained = list_entry(vc->desc_submitted.prev,
                                        struct virt_dma_desc, node);
                /*
                 * Only chain the descriptors if no new misalignment is
                 * introduced. If a new misalignment is chained, let the channel
                 * stop, and be relaunched in misalign mode from the irq
                 * handler.
                 */
                if (chan->misaligned || !to_pxad_sw_desc(vd)->misaligned)
                        pxad_desc_chain(vd_chained, vd);
                else
                        vd_chained = NULL;
        }
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): txd %p[%x]: submitted (%s linked)\n",
                __func__, vd, cookie, vd_chained ? "cold" : "not");
        list_move_tail(&vd->node, &vc->desc_submitted);
        chan->misaligned |= to_pxad_sw_desc(vd)->misaligned;

out:
        spin_unlock_irqrestore(&vc->lock, flags);
        return cookie;
}

static void pxad_issue_pending(struct dma_chan *dchan)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct virt_dma_desc *vd_first;
        unsigned long flags;

        spin_lock_irqsave(&chan->vc.lock, flags);
        if (list_empty(&chan->vc.desc_submitted))
                goto out;

        vd_first = list_first_entry(&chan->vc.desc_submitted,
                                    struct virt_dma_desc, node);
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): txd %p[%x]", __func__, vd_first, vd_first->tx.cookie);

        vchan_issue_pending(&chan->vc);
        if (!pxad_try_hotchain(&chan->vc, vd_first))
                pxad_launch_chan(chan, to_pxad_sw_desc(vd_first));
out:
        spin_unlock_irqrestore(&chan->vc.lock, flags);
}

static inline struct dma_async_tx_descriptor *
pxad_tx_prep(struct virt_dma_chan *vc, struct virt_dma_desc *vd,
                 unsigned long tx_flags)
{
        struct dma_async_tx_descriptor *tx;
        struct pxad_chan *chan = container_of(vc, struct pxad_chan, vc);

        INIT_LIST_HEAD(&vd->node);
        tx = vchan_tx_prep(vc, vd, tx_flags);
        tx->tx_submit = pxad_tx_submit;
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): vc=%p txd=%p[%x] flags=0x%lx\n", __func__,
                vc, vd, vd->tx.cookie,
                tx_flags);

        return tx;
}

static void pxad_get_config(struct pxad_chan *chan,
                            enum dma_transfer_direction dir,
                            u32 *dcmd, u32 *dev_src, u32 *dev_dst)
{
        u32 maxburst = 0, dev_addr = 0;
        enum dma_slave_buswidth width = DMA_SLAVE_BUSWIDTH_UNDEFINED;
        struct pxad_device *pdev = to_pxad_dev(chan->vc.chan.device);

        *dcmd = 0;
        if (dir == DMA_DEV_TO_MEM) {
                maxburst = chan->cfg.src_maxburst;
                width = chan->cfg.src_addr_width;
                dev_addr = chan->cfg.src_addr;
                *dev_src = dev_addr;
                *dcmd |= PXA_DCMD_INCTRGADDR;
                if (chan->drcmr <= pdev->nr_requestors)
                        *dcmd |= PXA_DCMD_FLOWSRC;
        }
        if (dir == DMA_MEM_TO_DEV) {
                maxburst = chan->cfg.dst_maxburst;
                width = chan->cfg.dst_addr_width;
                dev_addr = chan->cfg.dst_addr;
                *dev_dst = dev_addr;
                *dcmd |= PXA_DCMD_INCSRCADDR;
                if (chan->drcmr <= pdev->nr_requestors)
                        *dcmd |= PXA_DCMD_FLOWTRG;
        }
        if (dir == DMA_MEM_TO_MEM)
                *dcmd |= PXA_DCMD_BURST32 | PXA_DCMD_INCTRGADDR |
                        PXA_DCMD_INCSRCADDR;

        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): dev_addr=0x%x maxburst=%d width=%d  dir=%d\n",
                __func__, dev_addr, maxburst, width, dir);

        if (width == DMA_SLAVE_BUSWIDTH_1_BYTE)
                *dcmd |= PXA_DCMD_WIDTH1;
        else if (width == DMA_SLAVE_BUSWIDTH_2_BYTES)
                *dcmd |= PXA_DCMD_WIDTH2;
        else if (width == DMA_SLAVE_BUSWIDTH_4_BYTES)
                *dcmd |= PXA_DCMD_WIDTH4;

        if (maxburst == 8)
                *dcmd |= PXA_DCMD_BURST8;
        else if (maxburst == 16)
                *dcmd |= PXA_DCMD_BURST16;
        else if (maxburst == 32)
                *dcmd |= PXA_DCMD_BURST32;

        /* FIXME: drivers should be ported over to use the filter
         * function. Once that's done, the following two lines can
         * be removed.
         */
        if (chan->cfg.slave_id)
                chan->drcmr = chan->cfg.slave_id;
}

static struct dma_async_tx_descriptor *
pxad_prep_memcpy(struct dma_chan *dchan,
                 dma_addr_t dma_dst, dma_addr_t dma_src,
                 size_t len, unsigned long flags)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct pxad_desc_sw *sw_desc;
        struct pxad_desc_hw *hw_desc;
        u32 dcmd;
        unsigned int i, nb_desc = 0;
        size_t copy;

        if (!dchan || !len)
                return NULL;

        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): dma_dst=0x%lx dma_src=0x%lx len=%zu flags=%lx\n",
                __func__, (unsigned long)dma_dst, (unsigned long)dma_src,
                len, flags);
        pxad_get_config(chan, DMA_MEM_TO_MEM, &dcmd, NULL, NULL);

        nb_desc = DIV_ROUND_UP(len, PDMA_MAX_DESC_BYTES);
        sw_desc = pxad_alloc_desc(chan, nb_desc + 1);
        if (!sw_desc)
                return NULL;
        sw_desc->len = len;

        if (!IS_ALIGNED(dma_src, 1 << PDMA_ALIGNMENT) ||
            !IS_ALIGNED(dma_dst, 1 << PDMA_ALIGNMENT))
                sw_desc->misaligned = true;

        i = 0;
        do {
                hw_desc = sw_desc->hw_desc[i++];
                copy = min_t(size_t, len, PDMA_MAX_DESC_BYTES);
                hw_desc->dcmd = dcmd | (PXA_DCMD_LENGTH & copy);
                hw_desc->dsadr = dma_src;
                hw_desc->dtadr = dma_dst;
                len -= copy;
                dma_src += copy;
                dma_dst += copy;

        } while (len);
        set_updater_desc(sw_desc, flags);

        return pxad_tx_prep(&chan->vc, &sw_desc->vd, flags);
}

static struct dma_async_tx_descriptor *
pxad_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
                   unsigned int sg_len, enum dma_transfer_direction dir,
                   unsigned long flags, void *context)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct pxad_desc_sw *sw_desc;
        size_t len, avail;
        struct scatterlist *sg;
        dma_addr_t dma;
        u32 dcmd, dsadr = 0, dtadr = 0;
        unsigned int nb_desc = 0, i, j = 0;

        if ((sgl == NULL) || (sg_len == 0))
                return NULL;

        pxad_get_config(chan, dir, &dcmd, &dsadr, &dtadr);
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): dir=%d flags=%lx\n", __func__, dir, flags);

        for_each_sg(sgl, sg, sg_len, i)
                nb_desc += DIV_ROUND_UP(sg_dma_len(sg), PDMA_MAX_DESC_BYTES);
        sw_desc = pxad_alloc_desc(chan, nb_desc + 1);
        if (!sw_desc)
                return NULL;

        for_each_sg(sgl, sg, sg_len, i) {
                dma = sg_dma_address(sg);
                avail = sg_dma_len(sg);
                sw_desc->len += avail;

                do {
                        len = min_t(size_t, avail, PDMA_MAX_DESC_BYTES);
                        if (dma & 0x7)
                                sw_desc->misaligned = true;

                        sw_desc->hw_desc[j]->dcmd =
                                dcmd | (PXA_DCMD_LENGTH & len);
                        sw_desc->hw_desc[j]->dsadr = dsadr ? dsadr : dma;
                        sw_desc->hw_desc[j++]->dtadr = dtadr ? dtadr : dma;

                        dma += len;
                        avail -= len;
                } while (avail);
        }
        set_updater_desc(sw_desc, flags);

        return pxad_tx_prep(&chan->vc, &sw_desc->vd, flags);
}

static struct dma_async_tx_descriptor *
pxad_prep_dma_cyclic(struct dma_chan *dchan,
                     dma_addr_t buf_addr, size_t len, size_t period_len,
                     enum dma_transfer_direction dir, unsigned long flags)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct pxad_desc_sw *sw_desc;
        struct pxad_desc_hw **phw_desc;
        dma_addr_t dma;
        u32 dcmd, dsadr = 0, dtadr = 0;
        unsigned int nb_desc = 0;

        if (!dchan || !len || !period_len)
                return NULL;
        if ((dir != DMA_DEV_TO_MEM) && (dir != DMA_MEM_TO_DEV)) {
                dev_err(&chan->vc.chan.dev->device,
                        "Unsupported direction for cyclic DMA\n");
                return NULL;
        }
        /* the buffer length must be a multiple of period_len */
        if (len % period_len != 0 || period_len > PDMA_MAX_DESC_BYTES ||
            !IS_ALIGNED(period_len, 1 << PDMA_ALIGNMENT))
                return NULL;

        pxad_get_config(chan, dir, &dcmd, &dsadr, &dtadr);
        dcmd |= PXA_DCMD_ENDIRQEN | (PXA_DCMD_LENGTH & period_len);
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): buf_addr=0x%lx len=%zu period=%zu dir=%d flags=%lx\n",
                __func__, (unsigned long)buf_addr, len, period_len, dir, flags);

        nb_desc = DIV_ROUND_UP(period_len, PDMA_MAX_DESC_BYTES);
        nb_desc *= DIV_ROUND_UP(len, period_len);
        sw_desc = pxad_alloc_desc(chan, nb_desc + 1);
        if (!sw_desc)
                return NULL;
        sw_desc->cyclic = true;
        sw_desc->len = len;

        phw_desc = sw_desc->hw_desc;
        dma = buf_addr;
        do {
                phw_desc[0]->dsadr = dsadr ? dsadr : dma;
                phw_desc[0]->dtadr = dtadr ? dtadr : dma;
                phw_desc[0]->dcmd = dcmd;
                phw_desc++;
                dma += period_len;
                len -= period_len;
        } while (len);
        set_updater_desc(sw_desc, flags);

        return pxad_tx_prep(&chan->vc, &sw_desc->vd, flags);
}

static int pxad_config(struct dma_chan *dchan,
                       struct dma_slave_config *cfg)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);

        if (!dchan)
                return -EINVAL;

        chan->cfg = *cfg;
        return 0;
}

static int pxad_terminate_all(struct dma_chan *dchan)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        struct pxad_device *pdev = to_pxad_dev(chan->vc.chan.device);
        struct virt_dma_desc *vd = NULL;
        unsigned long flags;
        struct pxad_phy *phy;
        LIST_HEAD(head);

        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): vchan %p: terminate all\n", __func__, &chan->vc);

        spin_lock_irqsave(&chan->vc.lock, flags);
        vchan_get_all_descriptors(&chan->vc, &head);

        list_for_each_entry(vd, &head, node) {
                dev_dbg(&chan->vc.chan.dev->device,
                        "%s(): cancelling txd %p[%x] (completed=%d)", __func__,
                        vd, vd->tx.cookie, is_desc_completed(vd));
        }

        phy = chan->phy;
        if (phy) {
                phy_disable(chan->phy);
                pxad_free_phy(chan);
                chan->phy = NULL;
                spin_lock(&pdev->phy_lock);
                phy->vchan = NULL;
                spin_unlock(&pdev->phy_lock);
        }
        spin_unlock_irqrestore(&chan->vc.lock, flags);
        vchan_dma_desc_free_list(&chan->vc, &head);

        return 0;
}

static unsigned int pxad_residue(struct pxad_chan *chan,
                                 dma_cookie_t cookie)
{
        struct virt_dma_desc *vd = NULL;
        struct pxad_desc_sw *sw_desc = NULL;
        struct pxad_desc_hw *hw_desc = NULL;
        u32 curr, start, len, end, residue = 0;
        unsigned long flags;
        bool passed = false;
        int i;

        /*
         * If the channel does not have a phy pointer anymore, it has already
         * been completed. Therefore, its residue is 0.
         */
        if (!chan->phy)
                return 0;

        spin_lock_irqsave(&chan->vc.lock, flags);

        vd = vchan_find_desc(&chan->vc, cookie);
        if (!vd)
                goto out;

        sw_desc = to_pxad_sw_desc(vd);
        if (sw_desc->hw_desc[0]->dcmd & PXA_DCMD_INCSRCADDR)
                curr = phy_readl_relaxed(chan->phy, DSADR);
        else
                curr = phy_readl_relaxed(chan->phy, DTADR);

        /*
         * curr has to be actually read before checking descriptor
         * completion, so that a curr inside a status updater
         * descriptor implies the following test returns true, and
         * preventing reordering of curr load and the test.
         */
        rmb();
        if (is_desc_completed(vd))
                goto out;

        for (i = 0; i < sw_desc->nb_desc - 1; i++) {
                hw_desc = sw_desc->hw_desc[i];
                if (sw_desc->hw_desc[0]->dcmd & PXA_DCMD_INCSRCADDR)
                        start = hw_desc->dsadr;
                else
                        start = hw_desc->dtadr;
                len = hw_desc->dcmd & PXA_DCMD_LENGTH;
                end = start + len;

                /*
                 * 'passed' will be latched once we found the descriptor
                 * which lies inside the boundaries of the curr
                 * pointer. All descriptors that occur in the list
                 * _after_ we found that partially handled descriptor
                 * are still to be processed and are hence added to the
                 * residual bytes counter.
                 */

                if (passed) {
                        residue += len;
                } else if (curr >= start && curr <= end) {
                        residue += end - curr;
                        passed = true;
                }
        }
        if (!passed)
                residue = sw_desc->len;

out:
        spin_unlock_irqrestore(&chan->vc.lock, flags);
        dev_dbg(&chan->vc.chan.dev->device,
                "%s(): txd %p[%x] sw_desc=%p: %d\n",
                __func__, vd, cookie, sw_desc, residue);
        return residue;
}

static enum dma_status pxad_tx_status(struct dma_chan *dchan,
                                      dma_cookie_t cookie,
                                      struct dma_tx_state *txstate)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);
        enum dma_status ret;

        if (cookie == chan->bus_error)
                return DMA_ERROR;

        ret = dma_cookie_status(dchan, cookie, txstate);
        if (likely(txstate && (ret != DMA_ERROR)))
                dma_set_residue(txstate, pxad_residue(chan, cookie));

        return ret;
}

static void pxad_synchronize(struct dma_chan *dchan)
{
        struct pxad_chan *chan = to_pxad_chan(dchan);

        wait_event(chan->wq_state, !is_chan_running(chan));
        vchan_synchronize(&chan->vc);
}

static void pxad_free_channels(struct dma_device *dmadev)
{
        struct pxad_chan *c, *cn;

        list_for_each_entry_safe(c, cn, &dmadev->channels,
                                 vc.chan.device_node) {
                list_del(&c->vc.chan.device_node);
                tasklet_kill(&c->vc.task);
        }
}

static int pxad_remove(struct platform_device *op)
{
        struct pxad_device *pdev = platform_get_drvdata(op);

        pxad_cleanup_debugfs(pdev);
        pxad_free_channels(&pdev->slave);
        return 0;
}

static int pxad_init_phys(struct platform_device *op,
                          struct pxad_device *pdev,
                          unsigned int nb_phy_chans)
{
        int irq0, irq, nr_irq = 0, i, ret;
        struct pxad_phy *phy;

        irq0 = platform_get_irq(op, 0);
        if (irq0 < 0)
                return irq0;

        pdev->phys = devm_kcalloc(&op->dev, nb_phy_chans,
                                  sizeof(pdev->phys[0]), GFP_KERNEL);
        if (!pdev->phys)
                return -ENOMEM;

        for (i = 0; i < nb_phy_chans; i++)
                if (platform_get_irq(op, i) > 0)
                        nr_irq++;

        for (i = 0; i < nb_phy_chans; i++) {
                phy = &pdev->phys[i];
                phy->base = pdev->base;
                phy->idx = i;
                irq = platform_get_irq(op, i);
                if ((nr_irq > 1) && (irq > 0))
                        ret = devm_request_irq(&op->dev, irq,
                                               pxad_chan_handler,
                                               IRQF_SHARED, "pxa-dma", phy);
                if ((nr_irq == 1) && (i == 0))
                        ret = devm_request_irq(&op->dev, irq0,
                                               pxad_int_handler,
                                               IRQF_SHARED, "pxa-dma", pdev);
                if (ret) {
                        dev_err(pdev->slave.dev,
                                "%s(): can't request irq %d:%d\n", __func__,
                                irq, ret);
                        return ret;
                }
        }

        return 0;
}

static const struct of_device_id pxad_dt_ids[] = {
        { .compatible = "marvell,pdma-1.0", },
        {}
};
MODULE_DEVICE_TABLE(of, pxad_dt_ids);

static struct dma_chan *pxad_dma_xlate(struct of_phandle_args *dma_spec,
                                           struct of_dma *ofdma)
{
        struct pxad_device *d = ofdma->of_dma_data;
        struct dma_chan *chan;

        chan = dma_get_any_slave_channel(&d->slave);
        if (!chan)
                return NULL;

        to_pxad_chan(chan)->drcmr = dma_spec->args[0];
        to_pxad_chan(chan)->prio = dma_spec->args[1];

        return chan;
}

static int pxad_init_dmadev(struct platform_device *op,
                            struct pxad_device *pdev,
                            unsigned int nr_phy_chans,
                            unsigned int nr_requestors)
{
        int ret;
        unsigned int i;
        struct pxad_chan *c;

        pdev->nr_chans = nr_phy_chans;
        pdev->nr_requestors = nr_requestors;
        INIT_LIST_HEAD(&pdev->slave.channels);
        pdev->slave.device_alloc_chan_resources = pxad_alloc_chan_resources;
        pdev->slave.device_free_chan_resources = pxad_free_chan_resources;
        pdev->slave.device_tx_status = pxad_tx_status;
        pdev->slave.device_issue_pending = pxad_issue_pending;
        pdev->slave.device_config = pxad_config;
        pdev->slave.device_synchronize = pxad_synchronize;
        pdev->slave.device_terminate_all = pxad_terminate_all;

        if (op->dev.coherent_dma_mask)
                dma_set_mask(&op->dev, op->dev.coherent_dma_mask);
        else
                dma_set_mask(&op->dev, DMA_BIT_MASK(32));

        ret = pxad_init_phys(op, pdev, nr_phy_chans);
        if (ret)
                return ret;

        for (i = 0; i < nr_phy_chans; i++) {
                c = devm_kzalloc(&op->dev, sizeof(*c), GFP_KERNEL);
                if (!c)
                        return -ENOMEM;

                c->drcmr = U32_MAX;
                c->prio = PXAD_PRIO_LOWEST;
                c->vc.desc_free = pxad_free_desc;
                vchan_init(&c->vc, &pdev->slave);
                init_waitqueue_head(&c->wq_state);
        }

        return dmaenginem_async_device_register(&pdev->slave);
}

static int pxad_probe(struct platform_device *op)
{
        struct pxad_device *pdev;
        const struct of_device_id *of_id;
        const struct dma_slave_map *slave_map = NULL;
        struct mmp_dma_platdata *pdata = dev_get_platdata(&op->dev);
        struct resource *iores;
        int ret, dma_channels = 0, nb_requestors = 0, slave_map_cnt = 0;
        const enum dma_slave_buswidth widths =
                DMA_SLAVE_BUSWIDTH_1_BYTE   | DMA_SLAVE_BUSWIDTH_2_BYTES |
                DMA_SLAVE_BUSWIDTH_4_BYTES;

        pdev = devm_kzalloc(&op->dev, sizeof(*pdev), GFP_KERNEL);
        if (!pdev)
                return -ENOMEM;

        spin_lock_init(&pdev->phy_lock);

        iores = platform_get_resource(op, IORESOURCE_MEM, 0);
        pdev->base = devm_ioremap_resource(&op->dev, iores);
        if (IS_ERR(pdev->base))
                return PTR_ERR(pdev->base);

        of_id = of_match_device(pxad_dt_ids, &op->dev);
        if (of_id) {
                of_property_read_u32(op->dev.of_node, "#dma-channels",
                                     &dma_channels);
                ret = of_property_read_u32(op->dev.of_node, "#dma-requests",
                                           &nb_requestors);
                if (ret) {
                        dev_warn(pdev->slave.dev,
                                 "#dma-requests set to default 32 as missing in OF: %d",
                                 ret);
                        nb_requestors = 32;
                }
        } else if (pdata && pdata->dma_channels) {
                dma_channels = pdata->dma_channels;
                nb_requestors = pdata->nb_requestors;
                slave_map = pdata->slave_map;
                slave_map_cnt = pdata->slave_map_cnt;
        } else {
                dma_channels = 32;      /* default 32 channel */
        }

        dma_cap_set(DMA_SLAVE, pdev->slave.cap_mask);
        dma_cap_set(DMA_MEMCPY, pdev->slave.cap_mask);
        dma_cap_set(DMA_CYCLIC, pdev->slave.cap_mask);
        dma_cap_set(DMA_PRIVATE, pdev->slave.cap_mask);
        pdev->slave.device_prep_dma_memcpy = pxad_prep_memcpy;
        pdev->slave.device_prep_slave_sg = pxad_prep_slave_sg;
        pdev->slave.device_prep_dma_cyclic = pxad_prep_dma_cyclic;
        pdev->slave.filter.map = slave_map;
        pdev->slave.filter.mapcnt = slave_map_cnt;
        pdev->slave.filter.fn = pxad_filter_fn;

        pdev->slave.copy_align = PDMA_ALIGNMENT;
        pdev->slave.src_addr_widths = widths;
        pdev->slave.dst_addr_widths = widths;
        pdev->slave.directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
        pdev->slave.residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
        pdev->slave.descriptor_reuse = true;

        pdev->slave.dev = &op->dev;
        ret = pxad_init_dmadev(op, pdev, dma_channels, nb_requestors);
        if (ret) {
                dev_err(pdev->slave.dev, "unable to register\n");
                return ret;
        }

        if (op->dev.of_node) {
                /* Device-tree DMA controller registration */
                ret = of_dma_controller_register(op->dev.of_node,
                                                 pxad_dma_xlate, pdev);
                if (ret < 0) {
                        dev_err(pdev->slave.dev,
                                "of_dma_controller_register failed\n");
                        return ret;
                }
        }

        platform_set_drvdata(op, pdev);
        pxad_init_debugfs(pdev);
        dev_info(pdev->slave.dev, "initialized %d channels on %d requestors\n",
                 dma_channels, nb_requestors);
        return 0;
}

static const struct platform_device_id pxad_id_table[] = {
        { "pxa-dma", },
        { },
};

static struct platform_driver pxad_driver = {
        .driver         = {
                .name   = "pxa-dma",
                .of_match_table = pxad_dt_ids,
        },
        .id_table       = pxad_id_table,
        .probe          = pxad_probe,
        .remove         = pxad_remove,
};

static bool pxad_filter_fn(struct dma_chan *chan, void *param)
{
        struct pxad_chan *c = to_pxad_chan(chan);
        struct pxad_param *p = param;

        if (chan->device->dev->driver != &pxad_driver.driver)
                return false;

        c->drcmr = p->drcmr;
        c->prio = p->prio;

        return true;
}

module_platform_driver(pxad_driver);

MODULE_DESCRIPTION("Marvell PXA Peripheral DMA Driver");
MODULE_AUTHOR("Robert Jarzmik <robert.jarzmik@free.fr>");
MODULE_LICENSE("GPL v2");