// SPDX-License-Identifier: GPL-2.0-only
/*
 * OMAP DMAengine support
 */
#include <linux/cpu_pm.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/omap-dma.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/of.h>
#include <linux/of_dma.h>

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

#define OMAP_SDMA_REQUESTS      127
#define OMAP_SDMA_CHANNELS      32

struct omap_dma_config {
        int lch_end;
        unsigned int rw_priority:1;
        unsigned int needs_busy_check:1;
        unsigned int may_lose_context:1;
        unsigned int needs_lch_clear:1;
};

struct omap_dma_context {
        u32 irqenable_l0;
        u32 irqenable_l1;
        u32 ocp_sysconfig;
        u32 gcr;
};

struct omap_dmadev {
        struct dma_device ddev;
        spinlock_t lock;
        void __iomem *base;
        const struct omap_dma_reg *reg_map;
        struct omap_system_dma_plat_info *plat;
        const struct omap_dma_config *cfg;
        struct notifier_block nb;
        struct omap_dma_context context;
        int lch_count;
        DECLARE_BITMAP(lch_bitmap, OMAP_SDMA_CHANNELS);
        struct mutex lch_lock;          /* for assigning logical channels */
        bool legacy;
        bool ll123_supported;
        struct dma_pool *desc_pool;
        unsigned dma_requests;
        spinlock_t irq_lock;
        uint32_t irq_enable_mask;
        struct omap_chan **lch_map;
};

struct omap_chan {
        struct virt_dma_chan vc;
        void __iomem *channel_base;
        const struct omap_dma_reg *reg_map;
        uint32_t ccr;

        struct dma_slave_config cfg;
        unsigned dma_sig;
        bool cyclic;
        bool paused;
        bool running;

        int dma_ch;
        struct omap_desc *desc;
        unsigned sgidx;
};

#define DESC_NXT_SV_REFRESH     (0x1 << 24)
#define DESC_NXT_SV_REUSE       (0x2 << 24)
#define DESC_NXT_DV_REFRESH     (0x1 << 26)
#define DESC_NXT_DV_REUSE       (0x2 << 26)
#define DESC_NTYPE_TYPE2        (0x2 << 29)

/* Type 2 descriptor with Source or Destination address update */
struct omap_type2_desc {
        uint32_t next_desc;
        uint32_t en;
        uint32_t addr; /* src or dst */
        uint16_t fn;
        uint16_t cicr;
        int16_t cdei;
        int16_t csei;
        int32_t cdfi;
        int32_t csfi;
} __packed;

struct omap_sg {
        dma_addr_t addr;
        uint32_t en;            /* number of elements (24-bit) */
        uint32_t fn;            /* number of frames (16-bit) */
        int32_t fi;             /* for double indexing */
        int16_t ei;             /* for double indexing */

        /* Linked list */
        struct omap_type2_desc *t2_desc;
        dma_addr_t t2_desc_paddr;
};

struct omap_desc {
        struct virt_dma_desc vd;
        bool using_ll;
        enum dma_transfer_direction dir;
        dma_addr_t dev_addr;
        bool polled;

        int32_t fi;             /* for OMAP_DMA_SYNC_PACKET / double indexing */
        int16_t ei;             /* for double indexing */
        uint8_t es;             /* CSDP_DATA_TYPE_xxx */
        uint32_t ccr;           /* CCR value */
        uint16_t clnk_ctrl;     /* CLNK_CTRL value */
        uint16_t cicr;          /* CICR value */
        uint32_t csdp;          /* CSDP value */

        unsigned sglen;
        struct omap_sg sg[] __counted_by(sglen);
};

enum {
        CAPS_0_SUPPORT_LL123    = BIT(20),      /* Linked List type1/2/3 */
        CAPS_0_SUPPORT_LL4      = BIT(21),      /* Linked List type4 */

        CCR_FS                  = BIT(5),
        CCR_READ_PRIORITY       = BIT(6),
        CCR_ENABLE              = BIT(7),
        CCR_AUTO_INIT           = BIT(8),       /* OMAP1 only */
        CCR_REPEAT              = BIT(9),       /* OMAP1 only */
        CCR_OMAP31_DISABLE      = BIT(10),      /* OMAP1 only */
        CCR_SUSPEND_SENSITIVE   = BIT(8),       /* OMAP2+ only */
        CCR_RD_ACTIVE           = BIT(9),       /* OMAP2+ only */
        CCR_WR_ACTIVE           = BIT(10),      /* OMAP2+ only */
        CCR_SRC_AMODE_CONSTANT  = 0 << 12,
        CCR_SRC_AMODE_POSTINC   = 1 << 12,
        CCR_SRC_AMODE_SGLIDX    = 2 << 12,
        CCR_SRC_AMODE_DBLIDX    = 3 << 12,
        CCR_DST_AMODE_CONSTANT  = 0 << 14,
        CCR_DST_AMODE_POSTINC   = 1 << 14,
        CCR_DST_AMODE_SGLIDX    = 2 << 14,
        CCR_DST_AMODE_DBLIDX    = 3 << 14,
        CCR_CONSTANT_FILL       = BIT(16),
        CCR_TRANSPARENT_COPY    = BIT(17),
        CCR_BS                  = BIT(18),
        CCR_SUPERVISOR          = BIT(22),
        CCR_PREFETCH            = BIT(23),
        CCR_TRIGGER_SRC         = BIT(24),
        CCR_BUFFERING_DISABLE   = BIT(25),
        CCR_WRITE_PRIORITY      = BIT(26),
        CCR_SYNC_ELEMENT        = 0,
        CCR_SYNC_FRAME          = CCR_FS,
        CCR_SYNC_BLOCK          = CCR_BS,
        CCR_SYNC_PACKET         = CCR_BS | CCR_FS,

        CSDP_DATA_TYPE_8        = 0,
        CSDP_DATA_TYPE_16       = 1,
        CSDP_DATA_TYPE_32       = 2,
        CSDP_SRC_PORT_EMIFF     = 0 << 2, /* OMAP1 only */
        CSDP_SRC_PORT_EMIFS     = 1 << 2, /* OMAP1 only */
        CSDP_SRC_PORT_OCP_T1    = 2 << 2, /* OMAP1 only */
        CSDP_SRC_PORT_TIPB      = 3 << 2, /* OMAP1 only */
        CSDP_SRC_PORT_OCP_T2    = 4 << 2, /* OMAP1 only */
        CSDP_SRC_PORT_MPUI      = 5 << 2, /* OMAP1 only */
        CSDP_SRC_PACKED         = BIT(6),
        CSDP_SRC_BURST_1        = 0 << 7,
        CSDP_SRC_BURST_16       = 1 << 7,
        CSDP_SRC_BURST_32       = 2 << 7,
        CSDP_SRC_BURST_64       = 3 << 7,
        CSDP_DST_PORT_EMIFF     = 0 << 9, /* OMAP1 only */
        CSDP_DST_PORT_EMIFS     = 1 << 9, /* OMAP1 only */
        CSDP_DST_PORT_OCP_T1    = 2 << 9, /* OMAP1 only */
        CSDP_DST_PORT_TIPB      = 3 << 9, /* OMAP1 only */
        CSDP_DST_PORT_OCP_T2    = 4 << 9, /* OMAP1 only */
        CSDP_DST_PORT_MPUI      = 5 << 9, /* OMAP1 only */
        CSDP_DST_PACKED         = BIT(13),
        CSDP_DST_BURST_1        = 0 << 14,
        CSDP_DST_BURST_16       = 1 << 14,
        CSDP_DST_BURST_32       = 2 << 14,
        CSDP_DST_BURST_64       = 3 << 14,
        CSDP_WRITE_NON_POSTED   = 0 << 16,
        CSDP_WRITE_POSTED       = 1 << 16,
        CSDP_WRITE_LAST_NON_POSTED = 2 << 16,

        CICR_TOUT_IE            = BIT(0),       /* OMAP1 only */
        CICR_DROP_IE            = BIT(1),
        CICR_HALF_IE            = BIT(2),
        CICR_FRAME_IE           = BIT(3),
        CICR_LAST_IE            = BIT(4),
        CICR_BLOCK_IE           = BIT(5),
        CICR_PKT_IE             = BIT(7),       /* OMAP2+ only */
        CICR_TRANS_ERR_IE       = BIT(8),       /* OMAP2+ only */
        CICR_SUPERVISOR_ERR_IE  = BIT(10),      /* OMAP2+ only */
        CICR_MISALIGNED_ERR_IE  = BIT(11),      /* OMAP2+ only */
        CICR_DRAIN_IE           = BIT(12),      /* OMAP2+ only */
        CICR_SUPER_BLOCK_IE     = BIT(14),      /* OMAP2+ only */

        CLNK_CTRL_ENABLE_LNK    = BIT(15),

        CDP_DST_VALID_INC       = 0 << 0,
        CDP_DST_VALID_RELOAD    = 1 << 0,
        CDP_DST_VALID_REUSE     = 2 << 0,
        CDP_SRC_VALID_INC       = 0 << 2,
        CDP_SRC_VALID_RELOAD    = 1 << 2,
        CDP_SRC_VALID_REUSE     = 2 << 2,
        CDP_NTYPE_TYPE1         = 1 << 4,
        CDP_NTYPE_TYPE2         = 2 << 4,
        CDP_NTYPE_TYPE3         = 3 << 4,
        CDP_TMODE_NORMAL        = 0 << 8,
        CDP_TMODE_LLIST         = 1 << 8,
        CDP_FAST                = BIT(10),
};

static const unsigned es_bytes[] = {
        [CSDP_DATA_TYPE_8] = 1,
        [CSDP_DATA_TYPE_16] = 2,
        [CSDP_DATA_TYPE_32] = 4,
};

static bool omap_dma_filter_fn(struct dma_chan *chan, void *param);
static struct of_dma_filter_info omap_dma_info = {
        .filter_fn = omap_dma_filter_fn,
};

static inline struct omap_dmadev *to_omap_dma_dev(struct dma_device *d)
{
        return container_of(d, struct omap_dmadev, ddev);
}

static inline struct omap_chan *to_omap_dma_chan(struct dma_chan *c)
{
        return container_of(c, struct omap_chan, vc.chan);
}

static inline struct omap_desc *to_omap_dma_desc(struct dma_async_tx_descriptor *t)
{
        return container_of(t, struct omap_desc, vd.tx);
}

static void omap_dma_desc_free(struct virt_dma_desc *vd)
{
        struct omap_desc *d = to_omap_dma_desc(&vd->tx);

        if (d->using_ll) {
                struct omap_dmadev *od = to_omap_dma_dev(vd->tx.chan->device);
                int i;

                for (i = 0; i < d->sglen; i++) {
                        if (d->sg[i].t2_desc)
                                dma_pool_free(od->desc_pool, d->sg[i].t2_desc,
                                              d->sg[i].t2_desc_paddr);
                }
        }

        kfree(d);
}

static void omap_dma_fill_type2_desc(struct omap_desc *d, int idx,
                                     enum dma_transfer_direction dir, bool last)
{
        struct omap_sg *sg = &d->sg[idx];
        struct omap_type2_desc *t2_desc = sg->t2_desc;

        if (idx)
                d->sg[idx - 1].t2_desc->next_desc = sg->t2_desc_paddr;
        if (last)
                t2_desc->next_desc = 0xfffffffc;

        t2_desc->en = sg->en;
        t2_desc->addr = sg->addr;
        t2_desc->fn = sg->fn & 0xffff;
        t2_desc->cicr = d->cicr;
        if (!last)
                t2_desc->cicr &= ~CICR_BLOCK_IE;

        switch (dir) {
        case DMA_DEV_TO_MEM:
                t2_desc->cdei = sg->ei;
                t2_desc->csei = d->ei;
                t2_desc->cdfi = sg->fi;
                t2_desc->csfi = d->fi;

                t2_desc->en |= DESC_NXT_DV_REFRESH;
                t2_desc->en |= DESC_NXT_SV_REUSE;
                break;
        case DMA_MEM_TO_DEV:
                t2_desc->cdei = d->ei;
                t2_desc->csei = sg->ei;
                t2_desc->cdfi = d->fi;
                t2_desc->csfi = sg->fi;

                t2_desc->en |= DESC_NXT_SV_REFRESH;
                t2_desc->en |= DESC_NXT_DV_REUSE;
                break;
        default:
                return;
        }

        t2_desc->en |= DESC_NTYPE_TYPE2;
}

static void omap_dma_write(uint32_t val, unsigned type, void __iomem *addr)
{
        switch (type) {
        case OMAP_DMA_REG_16BIT:
                writew_relaxed(val, addr);
                break;
        case OMAP_DMA_REG_2X16BIT:
                writew_relaxed(val, addr);
                writew_relaxed(val >> 16, addr + 2);
                break;
        case OMAP_DMA_REG_32BIT:
                writel_relaxed(val, addr);
                break;
        default:
                WARN_ON(1);
        }
}

static unsigned omap_dma_read(unsigned type, void __iomem *addr)
{
        unsigned val;

        switch (type) {
        case OMAP_DMA_REG_16BIT:
                val = readw_relaxed(addr);
                break;
        case OMAP_DMA_REG_2X16BIT:
                val = readw_relaxed(addr);
                val |= readw_relaxed(addr + 2) << 16;
                break;
        case OMAP_DMA_REG_32BIT:
                val = readl_relaxed(addr);
                break;
        default:
                WARN_ON(1);
                val = 0;
        }

        return val;
}

static void omap_dma_glbl_write(struct omap_dmadev *od, unsigned reg, unsigned val)
{
        const struct omap_dma_reg *r = od->reg_map + reg;

        WARN_ON(r->stride);

        omap_dma_write(val, r->type, od->base + r->offset);
}

static unsigned omap_dma_glbl_read(struct omap_dmadev *od, unsigned reg)
{
        const struct omap_dma_reg *r = od->reg_map + reg;

        WARN_ON(r->stride);

        return omap_dma_read(r->type, od->base + r->offset);
}

static void omap_dma_chan_write(struct omap_chan *c, unsigned reg, unsigned val)
{
        const struct omap_dma_reg *r = c->reg_map + reg;

        omap_dma_write(val, r->type, c->channel_base + r->offset);
}

static unsigned omap_dma_chan_read(struct omap_chan *c, unsigned reg)
{
        const struct omap_dma_reg *r = c->reg_map + reg;

        return omap_dma_read(r->type, c->channel_base + r->offset);
}

static void omap_dma_clear_csr(struct omap_chan *c)
{
        if (dma_omap1())
                omap_dma_chan_read(c, CSR);
        else
                omap_dma_chan_write(c, CSR, ~0);
}

static unsigned omap_dma_get_csr(struct omap_chan *c)
{
        unsigned val = omap_dma_chan_read(c, CSR);

        if (!dma_omap1())
                omap_dma_chan_write(c, CSR, val);

        return val;
}

static void omap_dma_clear_lch(struct omap_dmadev *od, int lch)
{
        struct omap_chan *c;
        int i;

        c = od->lch_map[lch];
        if (!c)
                return;

        for (i = CSDP; i <= od->cfg->lch_end; i++)
                omap_dma_chan_write(c, i, 0);
}

static void omap_dma_assign(struct omap_dmadev *od, struct omap_chan *c,
        unsigned lch)
{
        c->channel_base = od->base + od->plat->channel_stride * lch;

        od->lch_map[lch] = c;
}

static void omap_dma_start(struct omap_chan *c, struct omap_desc *d)
{
        struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
        uint16_t cicr = d->cicr;

        if (__dma_omap15xx(od->plat->dma_attr))
                omap_dma_chan_write(c, CPC, 0);
        else
                omap_dma_chan_write(c, CDAC, 0);

        omap_dma_clear_csr(c);

        if (d->using_ll) {
                uint32_t cdp = CDP_TMODE_LLIST | CDP_NTYPE_TYPE2 | CDP_FAST;

                if (d->dir == DMA_DEV_TO_MEM)
                        cdp |= (CDP_DST_VALID_RELOAD | CDP_SRC_VALID_REUSE);
                else
                        cdp |= (CDP_DST_VALID_REUSE | CDP_SRC_VALID_RELOAD);
                omap_dma_chan_write(c, CDP, cdp);

                omap_dma_chan_write(c, CNDP, d->sg[0].t2_desc_paddr);
                omap_dma_chan_write(c, CCDN, 0);
                omap_dma_chan_write(c, CCFN, 0xffff);
                omap_dma_chan_write(c, CCEN, 0xffffff);

                cicr &= ~CICR_BLOCK_IE;
        } else if (od->ll123_supported) {
                omap_dma_chan_write(c, CDP, 0);
        }

        /* Enable interrupts */
        omap_dma_chan_write(c, CICR, cicr);

        /* Enable channel */
        omap_dma_chan_write(c, CCR, d->ccr | CCR_ENABLE);

        c->running = true;
}

static void omap_dma_drain_chan(struct omap_chan *c)
{
        int i;
        u32 val;

        /* Wait for sDMA FIFO to drain */
        for (i = 0; ; i++) {
                val = omap_dma_chan_read(c, CCR);
                if (!(val & (CCR_RD_ACTIVE | CCR_WR_ACTIVE)))
                        break;

                if (i > 100)
                        break;

                udelay(5);
        }

        if (val & (CCR_RD_ACTIVE | CCR_WR_ACTIVE))
                dev_err(c->vc.chan.device->dev,
                        "DMA drain did not complete on lch %d\n",
                        c->dma_ch);
}

static int omap_dma_stop(struct omap_chan *c)
{
        struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
        uint32_t val;

        /* disable irq */
        omap_dma_chan_write(c, CICR, 0);

        omap_dma_clear_csr(c);

        val = omap_dma_chan_read(c, CCR);
        if (od->plat->errata & DMA_ERRATA_i541 && val & CCR_TRIGGER_SRC) {
                uint32_t sysconfig;

                sysconfig = omap_dma_glbl_read(od, OCP_SYSCONFIG);
                val = sysconfig & ~DMA_SYSCONFIG_MIDLEMODE_MASK;
                val |= DMA_SYSCONFIG_MIDLEMODE(DMA_IDLEMODE_NO_IDLE);
                omap_dma_glbl_write(od, OCP_SYSCONFIG, val);

                val = omap_dma_chan_read(c, CCR);
                val &= ~CCR_ENABLE;
                omap_dma_chan_write(c, CCR, val);

                if (!(c->ccr & CCR_BUFFERING_DISABLE))
                        omap_dma_drain_chan(c);

                omap_dma_glbl_write(od, OCP_SYSCONFIG, sysconfig);
        } else {
                if (!(val & CCR_ENABLE))
                        return -EINVAL;

                val &= ~CCR_ENABLE;
                omap_dma_chan_write(c, CCR, val);

                if (!(c->ccr & CCR_BUFFERING_DISABLE))
                        omap_dma_drain_chan(c);
        }

        mb();

        if (!__dma_omap15xx(od->plat->dma_attr) && c->cyclic) {
                val = omap_dma_chan_read(c, CLNK_CTRL);

                if (dma_omap1())
                        val |= 1 << 14; /* set the STOP_LNK bit */
                else
                        val &= ~CLNK_CTRL_ENABLE_LNK;

                omap_dma_chan_write(c, CLNK_CTRL, val);
        }
        c->running = false;
        return 0;
}

static void omap_dma_start_sg(struct omap_chan *c, struct omap_desc *d)
{
        struct omap_sg *sg = d->sg + c->sgidx;
        unsigned cxsa, cxei, cxfi;

        if (d->dir == DMA_DEV_TO_MEM || d->dir == DMA_MEM_TO_MEM) {
                cxsa = CDSA;
                cxei = CDEI;
                cxfi = CDFI;
        } else {
                cxsa = CSSA;
                cxei = CSEI;
                cxfi = CSFI;
        }

        omap_dma_chan_write(c, cxsa, sg->addr);
        omap_dma_chan_write(c, cxei, sg->ei);
        omap_dma_chan_write(c, cxfi, sg->fi);
        omap_dma_chan_write(c, CEN, sg->en);
        omap_dma_chan_write(c, CFN, sg->fn);

        omap_dma_start(c, d);
        c->sgidx++;
}

static void omap_dma_start_desc(struct omap_chan *c)
{
        struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
        struct omap_desc *d;
        unsigned cxsa, cxei, cxfi;

        if (!vd) {
                c->desc = NULL;
                return;
        }

        list_del(&vd->node);

        c->desc = d = to_omap_dma_desc(&vd->tx);
        c->sgidx = 0;

        /*
         * This provides the necessary barrier to ensure data held in
         * DMA coherent memory is visible to the DMA engine prior to
         * the transfer starting.
         */
        mb();

        omap_dma_chan_write(c, CCR, d->ccr);
        if (dma_omap1())
                omap_dma_chan_write(c, CCR2, d->ccr >> 16);

        if (d->dir == DMA_DEV_TO_MEM || d->dir == DMA_MEM_TO_MEM) {
                cxsa = CSSA;
                cxei = CSEI;
                cxfi = CSFI;
        } else {
                cxsa = CDSA;
                cxei = CDEI;
                cxfi = CDFI;
        }

        omap_dma_chan_write(c, cxsa, d->dev_addr);
        omap_dma_chan_write(c, cxei, d->ei);
        omap_dma_chan_write(c, cxfi, d->fi);
        omap_dma_chan_write(c, CSDP, d->csdp);
        omap_dma_chan_write(c, CLNK_CTRL, d->clnk_ctrl);

        omap_dma_start_sg(c, d);
}

static void omap_dma_callback(int ch, u16 status, void *data)
{
        struct omap_chan *c = data;
        struct omap_desc *d;
        unsigned long flags;

        spin_lock_irqsave(&c->vc.lock, flags);
        d = c->desc;
        if (d) {
                if (c->cyclic) {
                        vchan_cyclic_callback(&d->vd);
                } else if (d->using_ll || c->sgidx == d->sglen) {
                        omap_dma_start_desc(c);
                        vchan_cookie_complete(&d->vd);
                } else {
                        omap_dma_start_sg(c, d);
                }
        }
        spin_unlock_irqrestore(&c->vc.lock, flags);
}

static irqreturn_t omap_dma_irq(int irq, void *devid)
{
        struct omap_dmadev *od = devid;
        unsigned status, channel;

        spin_lock(&od->irq_lock);

        status = omap_dma_glbl_read(od, IRQSTATUS_L1);
        status &= od->irq_enable_mask;
        if (status == 0) {
                spin_unlock(&od->irq_lock);
                return IRQ_NONE;
        }

        while ((channel = ffs(status)) != 0) {
                unsigned mask, csr;
                struct omap_chan *c;

                channel -= 1;
                mask = BIT(channel);
                status &= ~mask;

                c = od->lch_map[channel];
                if (c == NULL) {
                        /* This should never happen */
                        dev_err(od->ddev.dev, "invalid channel %u\n", channel);
                        continue;
                }

                csr = omap_dma_get_csr(c);
                omap_dma_glbl_write(od, IRQSTATUS_L1, mask);

                omap_dma_callback(channel, csr, c);
        }

        spin_unlock(&od->irq_lock);

        return IRQ_HANDLED;
}

static int omap_dma_get_lch(struct omap_dmadev *od, int *lch)
{
        int channel;

        mutex_lock(&od->lch_lock);
        channel = find_first_zero_bit(od->lch_bitmap, od->lch_count);
        if (channel >= od->lch_count)
                goto out_busy;
        set_bit(channel, od->lch_bitmap);
        mutex_unlock(&od->lch_lock);

        omap_dma_clear_lch(od, channel);
        *lch = channel;

        return 0;

out_busy:
        mutex_unlock(&od->lch_lock);
        *lch = -EINVAL;

        return -EBUSY;
}

static void omap_dma_put_lch(struct omap_dmadev *od, int lch)
{
        omap_dma_clear_lch(od, lch);
        mutex_lock(&od->lch_lock);
        clear_bit(lch, od->lch_bitmap);
        mutex_unlock(&od->lch_lock);
}

static inline bool omap_dma_legacy(struct omap_dmadev *od)
{
        return IS_ENABLED(CONFIG_ARCH_OMAP1) && od->legacy;
}

static int omap_dma_alloc_chan_resources(struct dma_chan *chan)
{
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        struct omap_chan *c = to_omap_dma_chan(chan);
        struct device *dev = od->ddev.dev;
        int ret;

        if (omap_dma_legacy(od)) {
                ret = omap_request_dma(c->dma_sig, "DMA engine",
                                       omap_dma_callback, c, &c->dma_ch);
        } else {
                ret = omap_dma_get_lch(od, &c->dma_ch);
        }

        dev_dbg(dev, "allocating channel %u for %u\n", c->dma_ch, c->dma_sig);

        if (ret >= 0) {
                omap_dma_assign(od, c, c->dma_ch);

                if (!omap_dma_legacy(od)) {
                        unsigned val;

                        spin_lock_irq(&od->irq_lock);
                        val = BIT(c->dma_ch);
                        omap_dma_glbl_write(od, IRQSTATUS_L1, val);
                        od->irq_enable_mask |= val;
                        omap_dma_glbl_write(od, IRQENABLE_L1, od->irq_enable_mask);

                        val = omap_dma_glbl_read(od, IRQENABLE_L0);
                        val &= ~BIT(c->dma_ch);
                        omap_dma_glbl_write(od, IRQENABLE_L0, val);
                        spin_unlock_irq(&od->irq_lock);
                }
        }

        if (dma_omap1()) {
                if (__dma_omap16xx(od->plat->dma_attr)) {
                        c->ccr = CCR_OMAP31_DISABLE;
                        /* Duplicate what plat-omap/dma.c does */
                        c->ccr |= c->dma_ch + 1;
                } else {
                        c->ccr = c->dma_sig & 0x1f;
                }
        } else {
                c->ccr = c->dma_sig & 0x1f;
                c->ccr |= (c->dma_sig & ~0x1f) << 14;
        }
        if (od->plat->errata & DMA_ERRATA_IFRAME_BUFFERING)
                c->ccr |= CCR_BUFFERING_DISABLE;

        return ret;
}

static void omap_dma_free_chan_resources(struct dma_chan *chan)
{
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        struct omap_chan *c = to_omap_dma_chan(chan);

        if (!omap_dma_legacy(od)) {
                spin_lock_irq(&od->irq_lock);
                od->irq_enable_mask &= ~BIT(c->dma_ch);
                omap_dma_glbl_write(od, IRQENABLE_L1, od->irq_enable_mask);
                spin_unlock_irq(&od->irq_lock);
        }

        c->channel_base = NULL;
        od->lch_map[c->dma_ch] = NULL;
        vchan_free_chan_resources(&c->vc);

        if (omap_dma_legacy(od))
                omap_free_dma(c->dma_ch);
        else
                omap_dma_put_lch(od, c->dma_ch);

        dev_dbg(od->ddev.dev, "freeing channel %u used for %u\n", c->dma_ch,
                c->dma_sig);
        c->dma_sig = 0;
}

static size_t omap_dma_sg_size(struct omap_sg *sg)
{
        return sg->en * sg->fn;
}

static size_t omap_dma_desc_size(struct omap_desc *d)
{
        unsigned i;
        size_t size;

        for (size = i = 0; i < d->sglen; i++)
                size += omap_dma_sg_size(&d->sg[i]);

        return size * es_bytes[d->es];
}

static size_t omap_dma_desc_size_pos(struct omap_desc *d, dma_addr_t addr)
{
        unsigned i;
        size_t size, es_size = es_bytes[d->es];

        for (size = i = 0; i < d->sglen; i++) {
                size_t this_size = omap_dma_sg_size(&d->sg[i]) * es_size;

                if (size)
                        size += this_size;
                else if (addr >= d->sg[i].addr &&
                         addr < d->sg[i].addr + this_size)
                        size += d->sg[i].addr + this_size - addr;
        }
        return size;
}

/*
 * OMAP 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
 * read before the DMA controller finished disabling the channel.
 */
static uint32_t omap_dma_chan_read_3_3(struct omap_chan *c, unsigned reg)
{
        struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
        uint32_t val;

        val = omap_dma_chan_read(c, reg);
        if (val == 0 && od->plat->errata & DMA_ERRATA_3_3)
                val = omap_dma_chan_read(c, reg);

        return val;
}

static dma_addr_t omap_dma_get_src_pos(struct omap_chan *c)
{
        struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
        dma_addr_t addr, cdac;

        if (__dma_omap15xx(od->plat->dma_attr)) {
                addr = omap_dma_chan_read(c, CPC);
        } else {
                addr = omap_dma_chan_read_3_3(c, CSAC);
                cdac = omap_dma_chan_read_3_3(c, CDAC);

                /*
                 * CDAC == 0 indicates that the DMA transfer on the channel has
                 * not been started (no data has been transferred so far).
                 * Return the programmed source start address in this case.
                 */
                if (cdac == 0)
                        addr = omap_dma_chan_read(c, CSSA);
        }

        if (dma_omap1())
                addr |= omap_dma_chan_read(c, CSSA) & 0xffff0000;

        return addr;
}

static dma_addr_t omap_dma_get_dst_pos(struct omap_chan *c)
{
        struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
        dma_addr_t addr;

        if (__dma_omap15xx(od->plat->dma_attr)) {
                addr = omap_dma_chan_read(c, CPC);
        } else {
                addr = omap_dma_chan_read_3_3(c, CDAC);

                /*
                 * CDAC == 0 indicates that the DMA transfer on the channel
                 * has not been started (no data has been transferred so
                 * far).  Return the programmed destination start address in
                 * this case.
                 */
                if (addr == 0)
                        addr = omap_dma_chan_read(c, CDSA);
        }

        if (dma_omap1())
                addr |= omap_dma_chan_read(c, CDSA) & 0xffff0000;

        return addr;
}

static enum dma_status omap_dma_tx_status(struct dma_chan *chan,
        dma_cookie_t cookie, struct dma_tx_state *txstate)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        enum dma_status ret;
        unsigned long flags;
        struct omap_desc *d = NULL;

        ret = dma_cookie_status(chan, cookie, txstate);
        if (ret == DMA_COMPLETE)
                return ret;

        spin_lock_irqsave(&c->vc.lock, flags);
        if (c->desc && c->desc->vd.tx.cookie == cookie)
                d = c->desc;

        if (!txstate)
                goto out;

        if (d) {
                dma_addr_t pos;

                if (d->dir == DMA_MEM_TO_DEV)
                        pos = omap_dma_get_src_pos(c);
                else if (d->dir == DMA_DEV_TO_MEM  || d->dir == DMA_MEM_TO_MEM)
                        pos = omap_dma_get_dst_pos(c);
                else
                        pos = 0;

                txstate->residue = omap_dma_desc_size_pos(d, pos);
        } else {
                struct virt_dma_desc *vd = vchan_find_desc(&c->vc, cookie);

                if (vd)
                        txstate->residue = omap_dma_desc_size(
                                                to_omap_dma_desc(&vd->tx));
                else
                        txstate->residue = 0;
        }

out:
        if (ret == DMA_IN_PROGRESS && c->paused) {
                ret = DMA_PAUSED;
        } else if (d && d->polled && c->running) {
                uint32_t ccr = omap_dma_chan_read(c, CCR);
                /*
                 * The channel is no longer active, set the return value
                 * accordingly and mark it as completed
                 */
                if (!(ccr & CCR_ENABLE)) {
                        ret = DMA_COMPLETE;
                        omap_dma_start_desc(c);
                        vchan_cookie_complete(&d->vd);
                }
        }

        spin_unlock_irqrestore(&c->vc.lock, flags);

        return ret;
}

static void omap_dma_issue_pending(struct dma_chan *chan)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&c->vc.lock, flags);
        if (vchan_issue_pending(&c->vc) && !c->desc)
                omap_dma_start_desc(c);
        spin_unlock_irqrestore(&c->vc.lock, flags);
}

static struct dma_async_tx_descriptor *omap_dma_prep_slave_sg(
        struct dma_chan *chan, struct scatterlist *sgl, unsigned sglen,
        enum dma_transfer_direction dir, unsigned long tx_flags, void *context)
{
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        struct omap_chan *c = to_omap_dma_chan(chan);
        enum dma_slave_buswidth dev_width;
        struct scatterlist *sgent;
        struct omap_desc *d;
        dma_addr_t dev_addr;
        unsigned i, es, en, frame_bytes;
        bool ll_failed = false;
        u32 burst;
        u32 port_window, port_window_bytes;

        if (dir == DMA_DEV_TO_MEM) {
                dev_addr = c->cfg.src_addr;
                dev_width = c->cfg.src_addr_width;
                burst = c->cfg.src_maxburst;
                port_window = c->cfg.src_port_window_size;
        } else if (dir == DMA_MEM_TO_DEV) {
                dev_addr = c->cfg.dst_addr;
                dev_width = c->cfg.dst_addr_width;
                burst = c->cfg.dst_maxburst;
                port_window = c->cfg.dst_port_window_size;
        } else {
                dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
                return NULL;
        }

        /* Bus width translates to the element size (ES) */
        switch (dev_width) {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                es = CSDP_DATA_TYPE_8;
                break;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                es = CSDP_DATA_TYPE_16;
                break;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                es = CSDP_DATA_TYPE_32;
                break;
        default: /* not reached */
                return NULL;
        }

        /* Now allocate and setup the descriptor. */
        d = kzalloc_flex(*d, sg, sglen, GFP_ATOMIC);
        if (!d)
                return NULL;
        d->sglen = sglen;

        d->dir = dir;
        d->dev_addr = dev_addr;
        d->es = es;

        /* When the port_window is used, one frame must cover the window */
        if (port_window) {
                burst = port_window;
                port_window_bytes = port_window * es_bytes[es];

                d->ei = 1;
                /*
                 * One frame covers the port_window and by  configure
                 * the source frame index to be -1 * (port_window - 1)
                 * we instruct the sDMA that after a frame is processed
                 * it should move back to the start of the window.
                 */
                d->fi = -(port_window_bytes - 1);
        }

        d->ccr = c->ccr | CCR_SYNC_FRAME;
        if (dir == DMA_DEV_TO_MEM) {
                d->csdp = CSDP_DST_BURST_64 | CSDP_DST_PACKED;

                d->ccr |= CCR_DST_AMODE_POSTINC;
                if (port_window) {
                        d->ccr |= CCR_SRC_AMODE_DBLIDX;

                        if (port_window_bytes >= 64)
                                d->csdp |= CSDP_SRC_BURST_64;
                        else if (port_window_bytes >= 32)
                                d->csdp |= CSDP_SRC_BURST_32;
                        else if (port_window_bytes >= 16)
                                d->csdp |= CSDP_SRC_BURST_16;

                } else {
                        d->ccr |= CCR_SRC_AMODE_CONSTANT;
                }
        } else {
                d->csdp = CSDP_SRC_BURST_64 | CSDP_SRC_PACKED;

                d->ccr |= CCR_SRC_AMODE_POSTINC;
                if (port_window) {
                        d->ccr |= CCR_DST_AMODE_DBLIDX;

                        if (port_window_bytes >= 64)
                                d->csdp |= CSDP_DST_BURST_64;
                        else if (port_window_bytes >= 32)
                                d->csdp |= CSDP_DST_BURST_32;
                        else if (port_window_bytes >= 16)
                                d->csdp |= CSDP_DST_BURST_16;
                } else {
                        d->ccr |= CCR_DST_AMODE_CONSTANT;
                }
        }

        d->cicr = CICR_DROP_IE | CICR_BLOCK_IE;
        d->csdp |= es;

        if (dma_omap1()) {
                d->cicr |= CICR_TOUT_IE;

                if (dir == DMA_DEV_TO_MEM)
                        d->csdp |= CSDP_DST_PORT_EMIFF | CSDP_SRC_PORT_TIPB;
                else
                        d->csdp |= CSDP_DST_PORT_TIPB | CSDP_SRC_PORT_EMIFF;
        } else {
                if (dir == DMA_DEV_TO_MEM)
                        d->ccr |= CCR_TRIGGER_SRC;

                d->cicr |= CICR_MISALIGNED_ERR_IE | CICR_TRANS_ERR_IE;

                if (port_window)
                        d->csdp |= CSDP_WRITE_LAST_NON_POSTED;
        }
        if (od->plat->errata & DMA_ERRATA_PARALLEL_CHANNELS)
                d->clnk_ctrl = c->dma_ch;

        /*
         * Build our scatterlist entries: each contains the address,
         * the number of elements (EN) in each frame, and the number of
         * frames (FN).  Number of bytes for this entry = ES * EN * FN.
         *
         * Burst size translates to number of elements with frame sync.
         * Note: DMA engine defines burst to be the number of dev-width
         * transfers.
         */
        en = burst;
        frame_bytes = es_bytes[es] * en;

        if (sglen >= 2)
                d->using_ll = od->ll123_supported;

        for_each_sg(sgl, sgent, sglen, i) {
                struct omap_sg *osg = &d->sg[i];

                osg->addr = sg_dma_address(sgent);
                osg->en = en;
                osg->fn = sg_dma_len(sgent) / frame_bytes;

                if (d->using_ll) {
                        osg->t2_desc = dma_pool_alloc(od->desc_pool, GFP_ATOMIC,
                                                      &osg->t2_desc_paddr);
                        if (!osg->t2_desc) {
                                dev_err(chan->device->dev,
                                        "t2_desc[%d] allocation failed\n", i);
                                ll_failed = true;
                                d->using_ll = false;
                                continue;
                        }

                        omap_dma_fill_type2_desc(d, i, dir, (i == sglen - 1));
                }
        }

        /* Release the dma_pool entries if one allocation failed */
        if (ll_failed) {
                for (i = 0; i < d->sglen; i++) {
                        struct omap_sg *osg = &d->sg[i];

                        if (osg->t2_desc) {
                                dma_pool_free(od->desc_pool, osg->t2_desc,
                                              osg->t2_desc_paddr);
                                osg->t2_desc = NULL;
                        }
                }
        }

        return vchan_tx_prep(&c->vc, &d->vd, tx_flags);
}

static struct dma_async_tx_descriptor *omap_dma_prep_dma_cyclic(
        struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
        size_t period_len, enum dma_transfer_direction dir, unsigned long flags)
{
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        struct omap_chan *c = to_omap_dma_chan(chan);
        enum dma_slave_buswidth dev_width;
        struct omap_desc *d;
        dma_addr_t dev_addr;
        unsigned es;
        u32 burst;

        if (dir == DMA_DEV_TO_MEM) {
                dev_addr = c->cfg.src_addr;
                dev_width = c->cfg.src_addr_width;
                burst = c->cfg.src_maxburst;
        } else if (dir == DMA_MEM_TO_DEV) {
                dev_addr = c->cfg.dst_addr;
                dev_width = c->cfg.dst_addr_width;
                burst = c->cfg.dst_maxburst;
        } else {
                dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
                return NULL;
        }

        /* Bus width translates to the element size (ES) */
        switch (dev_width) {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                es = CSDP_DATA_TYPE_8;
                break;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                es = CSDP_DATA_TYPE_16;
                break;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                es = CSDP_DATA_TYPE_32;
                break;
        default: /* not reached */
                return NULL;
        }

        /* Now allocate and setup the descriptor. */
        d = kzalloc(sizeof(*d) + sizeof(d->sg[0]), GFP_ATOMIC);
        if (!d)
                return NULL;

        d->dir = dir;
        d->dev_addr = dev_addr;
        d->fi = burst;
        d->es = es;
        d->sglen = 1;
        d->sg[0].addr = buf_addr;
        d->sg[0].en = period_len / es_bytes[es];
        d->sg[0].fn = buf_len / period_len;

        d->ccr = c->ccr;
        if (dir == DMA_DEV_TO_MEM)
                d->ccr |= CCR_DST_AMODE_POSTINC | CCR_SRC_AMODE_CONSTANT;
        else
                d->ccr |= CCR_DST_AMODE_CONSTANT | CCR_SRC_AMODE_POSTINC;

        d->cicr = CICR_DROP_IE;
        if (flags & DMA_PREP_INTERRUPT)
                d->cicr |= CICR_FRAME_IE;

        d->csdp = es;

        if (dma_omap1()) {
                d->cicr |= CICR_TOUT_IE;

                if (dir == DMA_DEV_TO_MEM)
                        d->csdp |= CSDP_DST_PORT_EMIFF | CSDP_SRC_PORT_MPUI;
                else
                        d->csdp |= CSDP_DST_PORT_MPUI | CSDP_SRC_PORT_EMIFF;
        } else {
                if (burst)
                        d->ccr |= CCR_SYNC_PACKET;
                else
                        d->ccr |= CCR_SYNC_ELEMENT;

                if (dir == DMA_DEV_TO_MEM) {
                        d->ccr |= CCR_TRIGGER_SRC;
                        d->csdp |= CSDP_DST_PACKED;
                } else {
                        d->csdp |= CSDP_SRC_PACKED;
                }

                d->cicr |= CICR_MISALIGNED_ERR_IE | CICR_TRANS_ERR_IE;

                d->csdp |= CSDP_DST_BURST_64 | CSDP_SRC_BURST_64;
        }

        if (__dma_omap15xx(od->plat->dma_attr))
                d->ccr |= CCR_AUTO_INIT | CCR_REPEAT;
        else
                d->clnk_ctrl = c->dma_ch | CLNK_CTRL_ENABLE_LNK;

        c->cyclic = true;

        return vchan_tx_prep(&c->vc, &d->vd, flags);
}

static struct dma_async_tx_descriptor *omap_dma_prep_dma_memcpy(
        struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
        size_t len, unsigned long tx_flags)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        struct omap_desc *d;
        uint8_t data_type;

        d = kzalloc(sizeof(*d) + sizeof(d->sg[0]), GFP_ATOMIC);
        if (!d)
                return NULL;

        data_type = __ffs((src | dest | len));
        if (data_type > CSDP_DATA_TYPE_32)
                data_type = CSDP_DATA_TYPE_32;

        d->dir = DMA_MEM_TO_MEM;
        d->dev_addr = src;
        d->fi = 0;
        d->es = data_type;
        d->sglen = 1;
        d->sg[0].en = len / BIT(data_type);
        d->sg[0].fn = 1;
        d->sg[0].addr = dest;
        d->ccr = c->ccr;
        d->ccr |= CCR_DST_AMODE_POSTINC | CCR_SRC_AMODE_POSTINC;

        if (tx_flags & DMA_PREP_INTERRUPT)
                d->cicr |= CICR_FRAME_IE;
        else
                d->polled = true;

        d->csdp = data_type;

        if (dma_omap1()) {
                d->cicr |= CICR_TOUT_IE;
                d->csdp |= CSDP_DST_PORT_EMIFF | CSDP_SRC_PORT_EMIFF;
        } else {
                d->csdp |= CSDP_DST_PACKED | CSDP_SRC_PACKED;
                d->cicr |= CICR_MISALIGNED_ERR_IE | CICR_TRANS_ERR_IE;
                d->csdp |= CSDP_DST_BURST_64 | CSDP_SRC_BURST_64;
        }

        return vchan_tx_prep(&c->vc, &d->vd, tx_flags);
}

static struct dma_async_tx_descriptor *omap_dma_prep_dma_interleaved(
        struct dma_chan *chan, struct dma_interleaved_template *xt,
        unsigned long flags)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        struct omap_desc *d;
        struct omap_sg *sg;
        uint8_t data_type;
        size_t src_icg, dst_icg;

        /* Slave mode is not supported */
        if (is_slave_direction(xt->dir))
                return NULL;

        if (xt->frame_size != 1 || xt->numf == 0)
                return NULL;

        d = kzalloc(sizeof(*d) + sizeof(d->sg[0]), GFP_ATOMIC);
        if (!d)
                return NULL;

        data_type = __ffs((xt->src_start | xt->dst_start | xt->sgl[0].size));
        if (data_type > CSDP_DATA_TYPE_32)
                data_type = CSDP_DATA_TYPE_32;

        d->sglen = 1;
        sg = &d->sg[0];
        d->dir = DMA_MEM_TO_MEM;
        d->dev_addr = xt->src_start;
        d->es = data_type;
        sg->en = xt->sgl[0].size / BIT(data_type);
        sg->fn = xt->numf;
        sg->addr = xt->dst_start;
        d->ccr = c->ccr;

        src_icg = dmaengine_get_src_icg(xt, &xt->sgl[0]);
        dst_icg = dmaengine_get_dst_icg(xt, &xt->sgl[0]);
        if (src_icg) {
                d->ccr |= CCR_SRC_AMODE_DBLIDX;
                d->ei = 1;
                d->fi = src_icg + 1;
        } else if (xt->src_inc) {
                d->ccr |= CCR_SRC_AMODE_POSTINC;
                d->fi = 0;
        } else {
                dev_err(chan->device->dev,
                        "%s: SRC constant addressing is not supported\n",
                        __func__);
                kfree(d);
                return NULL;
        }

        if (dst_icg) {
                d->ccr |= CCR_DST_AMODE_DBLIDX;
                sg->ei = 1;
                sg->fi = dst_icg + 1;
        } else if (xt->dst_inc) {
                d->ccr |= CCR_DST_AMODE_POSTINC;
                sg->fi = 0;
        } else {
                dev_err(chan->device->dev,
                        "%s: DST constant addressing is not supported\n",
                        __func__);
                kfree(d);
                return NULL;
        }

        d->cicr = CICR_DROP_IE | CICR_FRAME_IE;

        d->csdp = data_type;

        if (dma_omap1()) {
                d->cicr |= CICR_TOUT_IE;
                d->csdp |= CSDP_DST_PORT_EMIFF | CSDP_SRC_PORT_EMIFF;
        } else {
                d->csdp |= CSDP_DST_PACKED | CSDP_SRC_PACKED;
                d->cicr |= CICR_MISALIGNED_ERR_IE | CICR_TRANS_ERR_IE;
                d->csdp |= CSDP_DST_BURST_64 | CSDP_SRC_BURST_64;
        }

        return vchan_tx_prep(&c->vc, &d->vd, flags);
}

static int omap_dma_slave_config(struct dma_chan *chan, struct dma_slave_config *cfg)
{
        struct omap_chan *c = to_omap_dma_chan(chan);

        if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
            cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
                return -EINVAL;

        if (cfg->src_maxburst > chan->device->max_burst ||
            cfg->dst_maxburst > chan->device->max_burst)
                return -EINVAL;

        memcpy(&c->cfg, cfg, sizeof(c->cfg));

        return 0;
}

static int omap_dma_terminate_all(struct dma_chan *chan)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        unsigned long flags;
        LIST_HEAD(head);

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

        /*
         * Stop DMA activity: we assume the callback will not be called
         * after omap_dma_stop() returns (even if it does, it will see
         * c->desc is NULL and exit.)
         */
        if (c->desc) {
                vchan_terminate_vdesc(&c->desc->vd);
                c->desc = NULL;
                /* Avoid stopping the dma twice */
                if (!c->paused)
                        omap_dma_stop(c);
        }

        c->cyclic = false;
        c->paused = false;

        vchan_get_all_descriptors(&c->vc, &head);
        spin_unlock_irqrestore(&c->vc.lock, flags);
        vchan_dma_desc_free_list(&c->vc, &head);

        return 0;
}

static void omap_dma_synchronize(struct dma_chan *chan)
{
        struct omap_chan *c = to_omap_dma_chan(chan);

        vchan_synchronize(&c->vc);
}

static int omap_dma_pause(struct dma_chan *chan)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        unsigned long flags;
        int ret = -EINVAL;
        bool can_pause = false;

        spin_lock_irqsave(&od->irq_lock, flags);

        if (!c->desc)
                goto out;

        if (c->cyclic)
                can_pause = true;

        /*
         * We do not allow DMA_MEM_TO_DEV transfers to be paused.
         * From the AM572x TRM, 16.1.4.18 Disabling a Channel During Transfer:
         * "When a channel is disabled during a transfer, the channel undergoes
         * an abort, unless it is hardware-source-synchronized …".
         * A source-synchronised channel is one where the fetching of data is
         * under control of the device. In other words, a device-to-memory
         * transfer. So, a destination-synchronised channel (which would be a
         * memory-to-device transfer) undergoes an abort if the CCR_ENABLE
         * bit is cleared.
         * From 16.1.4.20.4.6.2 Abort: "If an abort trigger occurs, the channel
         * aborts immediately after completion of current read/write
         * transactions and then the FIFO is cleaned up." The term "cleaned up"
         * is not defined. TI recommends to check that RD_ACTIVE and WR_ACTIVE
         * are both clear _before_ disabling the channel, otherwise data loss
         * will occur.
         * The problem is that if the channel is active, then device activity
         * can result in DMA activity starting between reading those as both
         * clear and the write to DMA_CCR to clear the enable bit hitting the
         * hardware. If the DMA hardware can't drain the data in its FIFO to the
         * destination, then data loss "might" occur (say if we write to an UART
         * and the UART is not accepting any further data).
         */
        else if (c->desc->dir == DMA_DEV_TO_MEM)
                can_pause = true;

        if (can_pause && !c->paused) {
                ret = omap_dma_stop(c);
                if (!ret)
                        c->paused = true;
        }
out:
        spin_unlock_irqrestore(&od->irq_lock, flags);

        return ret;
}

static int omap_dma_resume(struct dma_chan *chan)
{
        struct omap_chan *c = to_omap_dma_chan(chan);
        struct omap_dmadev *od = to_omap_dma_dev(chan->device);
        unsigned long flags;
        int ret = -EINVAL;

        spin_lock_irqsave(&od->irq_lock, flags);

        if (c->paused && c->desc) {
                mb();

                /* Restore channel link register */
                omap_dma_chan_write(c, CLNK_CTRL, c->desc->clnk_ctrl);

                omap_dma_start(c, c->desc);
                c->paused = false;
                ret = 0;
        }
        spin_unlock_irqrestore(&od->irq_lock, flags);

        return ret;
}

static int omap_dma_chan_init(struct omap_dmadev *od)
{
        struct omap_chan *c;

        c = kzalloc_obj(*c);
        if (!c)
                return -ENOMEM;

        c->reg_map = od->reg_map;
        c->vc.desc_free = omap_dma_desc_free;
        vchan_init(&c->vc, &od->ddev);

        return 0;
}

static void omap_dma_free(struct omap_dmadev *od)
{
        while (!list_empty(&od->ddev.channels)) {
                struct omap_chan *c = list_first_entry(&od->ddev.channels,
                        struct omap_chan, vc.chan.device_node);

                list_del(&c->vc.chan.device_node);
                tasklet_kill(&c->vc.task);
                kfree(c);
        }
}

/* Currently used by omap2 & 3 to block deeper SoC idle states */
static bool omap_dma_busy(struct omap_dmadev *od)
{
        struct omap_chan *c;
        int lch = -1;

        while (1) {
                lch = find_next_bit(od->lch_bitmap, od->lch_count, lch + 1);
                if (lch >= od->lch_count)
                        break;
                c = od->lch_map[lch];
                if (!c)
                        continue;
                if (omap_dma_chan_read(c, CCR) & CCR_ENABLE)
                        return true;
        }

        return false;
}

/* Currently only used for omap2. For omap1, also a check for lcd_dma is needed */
static int omap_dma_busy_notifier(struct notifier_block *nb,
                                  unsigned long cmd, void *v)
{
        struct omap_dmadev *od;

        od = container_of(nb, struct omap_dmadev, nb);

        switch (cmd) {
        case CPU_CLUSTER_PM_ENTER:
                if (omap_dma_busy(od))
                        return NOTIFY_BAD;
                break;
        case CPU_CLUSTER_PM_ENTER_FAILED:
        case CPU_CLUSTER_PM_EXIT:
                break;
        }

        return NOTIFY_OK;
}

/*
 * We are using IRQENABLE_L1, and legacy DMA code was using IRQENABLE_L0.
 * As the DSP may be using IRQENABLE_L2 and L3, let's not touch those for
 * now. Context save seems to be only currently needed on omap3.
 */
static void omap_dma_context_save(struct omap_dmadev *od)
{
        od->context.irqenable_l0 = omap_dma_glbl_read(od, IRQENABLE_L0);
        od->context.irqenable_l1 = omap_dma_glbl_read(od, IRQENABLE_L1);
        od->context.ocp_sysconfig = omap_dma_glbl_read(od, OCP_SYSCONFIG);
        od->context.gcr = omap_dma_glbl_read(od, GCR);
}

static void omap_dma_context_restore(struct omap_dmadev *od)
{
        int i;

        omap_dma_glbl_write(od, GCR, od->context.gcr);
        omap_dma_glbl_write(od, OCP_SYSCONFIG, od->context.ocp_sysconfig);
        omap_dma_glbl_write(od, IRQENABLE_L0, od->context.irqenable_l0);
        omap_dma_glbl_write(od, IRQENABLE_L1, od->context.irqenable_l1);

        /* Clear IRQSTATUS_L0 as legacy DMA code is no longer doing it */
        if (od->plat->errata & DMA_ROMCODE_BUG)
                omap_dma_glbl_write(od, IRQSTATUS_L0, 0);

        /* Clear dma channels */
        for (i = 0; i < od->lch_count; i++)
                omap_dma_clear_lch(od, i);
}

/* Currently only used for omap3 */
static int omap_dma_context_notifier(struct notifier_block *nb,
                                     unsigned long cmd, void *v)
{
        struct omap_dmadev *od;

        od = container_of(nb, struct omap_dmadev, nb);

        switch (cmd) {
        case CPU_CLUSTER_PM_ENTER:
                if (omap_dma_busy(od))
                        return NOTIFY_BAD;
                omap_dma_context_save(od);
                break;
        case CPU_CLUSTER_PM_ENTER_FAILED:       /* No need to restore context */
                break;
        case CPU_CLUSTER_PM_EXIT:
                omap_dma_context_restore(od);
                break;
        }

        return NOTIFY_OK;
}

static void omap_dma_init_gcr(struct omap_dmadev *od, int arb_rate,
                              int max_fifo_depth, int tparams)
{
        u32 val;

        /* Set only for omap2430 and later */
        if (!od->cfg->rw_priority)
                return;

        if (max_fifo_depth == 0)
                max_fifo_depth = 1;
        if (arb_rate == 0)
                arb_rate = 1;

        val = 0xff & max_fifo_depth;
        val |= (0x3 & tparams) << 12;
        val |= (arb_rate & 0xff) << 16;

        omap_dma_glbl_write(od, GCR, val);
}

#define OMAP_DMA_BUSWIDTHS      (BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
                                 BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
                                 BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))

/*
 * No flags currently set for default configuration as omap1 is still
 * using platform data.
 */
static const struct omap_dma_config default_cfg;

static int omap_dma_probe(struct platform_device *pdev)
{
        const struct omap_dma_config *conf;
        struct omap_dmadev *od;
        int rc, i, irq;
        u32 val;

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

        od->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(od->base))
                return PTR_ERR(od->base);

        conf = of_device_get_match_data(&pdev->dev);
        if (conf) {
                od->cfg = conf;
                od->plat = dev_get_platdata(&pdev->dev);
                if (!od->plat) {
                        dev_err(&pdev->dev, "omap_system_dma_plat_info is missing");
                        return -ENODEV;
                }
        } else if (IS_ENABLED(CONFIG_ARCH_OMAP1)) {
                od->cfg = &default_cfg;

                od->plat = omap_get_plat_info();
                if (!od->plat)
                        return -EPROBE_DEFER;
        } else {
                return -ENODEV;
        }

        od->reg_map = od->plat->reg_map;

        dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
        dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
        dma_cap_set(DMA_MEMCPY, od->ddev.cap_mask);
        dma_cap_set(DMA_INTERLEAVE, od->ddev.cap_mask);
        od->ddev.device_alloc_chan_resources = omap_dma_alloc_chan_resources;
        od->ddev.device_free_chan_resources = omap_dma_free_chan_resources;
        od->ddev.device_tx_status = omap_dma_tx_status;
        od->ddev.device_issue_pending = omap_dma_issue_pending;
        od->ddev.device_prep_slave_sg = omap_dma_prep_slave_sg;
        od->ddev.device_prep_dma_cyclic = omap_dma_prep_dma_cyclic;
        od->ddev.device_prep_dma_memcpy = omap_dma_prep_dma_memcpy;
        od->ddev.device_prep_interleaved_dma = omap_dma_prep_dma_interleaved;
        od->ddev.device_config = omap_dma_slave_config;
        od->ddev.device_pause = omap_dma_pause;
        od->ddev.device_resume = omap_dma_resume;
        od->ddev.device_terminate_all = omap_dma_terminate_all;
        od->ddev.device_synchronize = omap_dma_synchronize;
        od->ddev.src_addr_widths = OMAP_DMA_BUSWIDTHS;
        od->ddev.dst_addr_widths = OMAP_DMA_BUSWIDTHS;
        od->ddev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
        if (__dma_omap15xx(od->plat->dma_attr))
                od->ddev.residue_granularity =
                                DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
        else
                od->ddev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
        od->ddev.max_burst = SZ_16M - 1; /* CCEN: 24bit unsigned */
        od->ddev.dev = &pdev->dev;
        INIT_LIST_HEAD(&od->ddev.channels);
        mutex_init(&od->lch_lock);
        spin_lock_init(&od->lock);
        spin_lock_init(&od->irq_lock);

        /* Number of DMA requests */
        od->dma_requests = OMAP_SDMA_REQUESTS;
        if (pdev->dev.of_node && of_property_read_u32(pdev->dev.of_node,
                                                      "dma-requests",
                                                      &od->dma_requests)) {
                dev_info(&pdev->dev,
                         "Missing dma-requests property, using %u.\n",
                         OMAP_SDMA_REQUESTS);
        }

        /* Number of available logical channels */
        if (!pdev->dev.of_node) {
                od->lch_count = od->plat->dma_attr->lch_count;
                if (unlikely(!od->lch_count))
                        od->lch_count = OMAP_SDMA_CHANNELS;
        } else if (of_property_read_u32(pdev->dev.of_node, "dma-channels",
                                        &od->lch_count)) {
                dev_info(&pdev->dev,
                         "Missing dma-channels property, using %u.\n",
                         OMAP_SDMA_CHANNELS);
                od->lch_count = OMAP_SDMA_CHANNELS;
        }

        /* Mask of allowed logical channels */
        if (pdev->dev.of_node && !of_property_read_u32(pdev->dev.of_node,
                                                       "dma-channel-mask",
                                                       &val)) {
                /* Tag channels not in mask as reserved */
                val = ~val;
                bitmap_from_arr32(od->lch_bitmap, &val, od->lch_count);
        }
        if (od->plat->dma_attr->dev_caps & HS_CHANNELS_RESERVED)
                bitmap_set(od->lch_bitmap, 0, 2);

        od->lch_map = devm_kcalloc(&pdev->dev, od->lch_count,
                                   sizeof(*od->lch_map),
                                   GFP_KERNEL);
        if (!od->lch_map)
                return -ENOMEM;

        for (i = 0; i < od->dma_requests; i++) {
                rc = omap_dma_chan_init(od);
                if (rc) {
                        omap_dma_free(od);
                        return rc;
                }
        }

        irq = platform_get_irq(pdev, 1);
        if (irq <= 0) {
                dev_info(&pdev->dev, "failed to get L1 IRQ: %d\n", irq);
                od->legacy = true;
        } else {
                /* Disable all interrupts */
                od->irq_enable_mask = 0;
                omap_dma_glbl_write(od, IRQENABLE_L1, 0);

                rc = devm_request_irq(&pdev->dev, irq, omap_dma_irq,
                                      IRQF_SHARED, "omap-dma-engine", od);
                if (rc) {
                        omap_dma_free(od);
                        return rc;
                }
        }

        if (omap_dma_glbl_read(od, CAPS_0) & CAPS_0_SUPPORT_LL123)
                od->ll123_supported = true;

        od->ddev.filter.map = od->plat->slave_map;
        od->ddev.filter.mapcnt = od->plat->slavecnt;
        od->ddev.filter.fn = omap_dma_filter_fn;

        if (od->ll123_supported) {
                od->desc_pool = dma_pool_create(dev_name(&pdev->dev),
                                                &pdev->dev,
                                                sizeof(struct omap_type2_desc),
                                                4, 0);
                if (!od->desc_pool) {
                        dev_err(&pdev->dev,
                                "unable to allocate descriptor pool\n");
                        od->ll123_supported = false;
                }
        }

        rc = dma_async_device_register(&od->ddev);
        if (rc) {
                pr_warn("OMAP-DMA: failed to register slave DMA engine device: %d\n",
                        rc);
                if (od->ll123_supported)
                        dma_pool_destroy(od->desc_pool);
                omap_dma_free(od);
                return rc;
        }

        platform_set_drvdata(pdev, od);

        if (pdev->dev.of_node) {
                omap_dma_info.dma_cap = od->ddev.cap_mask;

                /* Device-tree DMA controller registration */
                rc = of_dma_controller_register(pdev->dev.of_node,
                                of_dma_simple_xlate, &omap_dma_info);
                if (rc) {
                        pr_warn("OMAP-DMA: failed to register DMA controller\n");
                        dma_async_device_unregister(&od->ddev);
                        if (od->ll123_supported)
                                dma_pool_destroy(od->desc_pool);
                        omap_dma_free(od);
                }
        }

        omap_dma_init_gcr(od, DMA_DEFAULT_ARB_RATE, DMA_DEFAULT_FIFO_DEPTH, 0);

        if (od->cfg->needs_busy_check) {
                od->nb.notifier_call = omap_dma_busy_notifier;
                cpu_pm_register_notifier(&od->nb);
        } else if (od->cfg->may_lose_context) {
                od->nb.notifier_call = omap_dma_context_notifier;
                cpu_pm_register_notifier(&od->nb);
        }

        dev_info(&pdev->dev, "OMAP DMA engine driver%s\n",
                 od->ll123_supported ? " (LinkedList1/2/3 supported)" : "");

        return rc;
}

static void omap_dma_remove(struct platform_device *pdev)
{
        struct omap_dmadev *od = platform_get_drvdata(pdev);
        int irq;

        if (od->cfg->may_lose_context)
                cpu_pm_unregister_notifier(&od->nb);

        if (pdev->dev.of_node)
                of_dma_controller_free(pdev->dev.of_node);

        irq = platform_get_irq(pdev, 1);
        devm_free_irq(&pdev->dev, irq, od);

        dma_async_device_unregister(&od->ddev);

        if (!omap_dma_legacy(od)) {
                /* Disable all interrupts */
                omap_dma_glbl_write(od, IRQENABLE_L0, 0);
        }

        if (od->ll123_supported)
                dma_pool_destroy(od->desc_pool);

        omap_dma_free(od);
}

static const struct omap_dma_config omap2420_data = {
        .lch_end = CCFN,
        .rw_priority = true,
        .needs_lch_clear = true,
        .needs_busy_check = true,
};

static const struct omap_dma_config omap2430_data = {
        .lch_end = CCFN,
        .rw_priority = true,
        .needs_lch_clear = true,
};

static const struct omap_dma_config omap3430_data = {
        .lch_end = CCFN,
        .rw_priority = true,
        .needs_lch_clear = true,
        .may_lose_context = true,
};

static const struct omap_dma_config omap3630_data = {
        .lch_end = CCDN,
        .rw_priority = true,
        .needs_lch_clear = true,
        .may_lose_context = true,
};

static const struct omap_dma_config omap4_data = {
        .lch_end = CCDN,
        .rw_priority = true,
        .needs_lch_clear = true,
};

static const struct of_device_id omap_dma_match[] = {
        { .compatible = "ti,omap2420-sdma", .data = &omap2420_data, },
        { .compatible = "ti,omap2430-sdma", .data = &omap2430_data, },
        { .compatible = "ti,omap3430-sdma", .data = &omap3430_data, },
        { .compatible = "ti,omap3630-sdma", .data = &omap3630_data, },
        { .compatible = "ti,omap4430-sdma", .data = &omap4_data, },
        {},
};
MODULE_DEVICE_TABLE(of, omap_dma_match);

static struct platform_driver omap_dma_driver = {
        .probe  = omap_dma_probe,
        .remove = omap_dma_remove,
        .driver = {
                .name = "omap-dma-engine",
                .of_match_table = omap_dma_match,
        },
};

static bool omap_dma_filter_fn(struct dma_chan *chan, void *param)
{
        if (chan->device->dev->driver == &omap_dma_driver.driver) {
                struct omap_dmadev *od = to_omap_dma_dev(chan->device);
                struct omap_chan *c = to_omap_dma_chan(chan);
                unsigned req = *(unsigned *)param;

                if (req <= od->dma_requests) {
                        c->dma_sig = req;
                        return true;
                }
        }
        return false;
}

static int omap_dma_init(void)
{
        return platform_driver_register(&omap_dma_driver);
}
subsys_initcall(omap_dma_init);

static void __exit omap_dma_exit(void)
{
        platform_driver_unregister(&omap_dma_driver);
}
module_exit(omap_dma_exit);

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("Texas Instruments sDMA DMAengine support");
MODULE_LICENSE("GPL");