/*
 * Copyright (C) 2013-2014 Allwinner Tech Co., Ltd
 * Author: Sugar <shuge@allwinnertech.com>
 *
 * Copyright (C) 2014 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dmapool.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_dma.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/slab.h>
#include <linux/types.h>

#include "virt-dma.h"

/*
 * Common registers
 */
#define DMA_IRQ_EN(x)           ((x) * 0x04)
#define DMA_IRQ_HALF                    BIT(0)
#define DMA_IRQ_PKG                     BIT(1)
#define DMA_IRQ_QUEUE                   BIT(2)

#define DMA_IRQ_CHAN_NR                 8
#define DMA_IRQ_CHAN_WIDTH              4


#define DMA_IRQ_STAT(x)         ((x) * 0x04 + 0x10)

#define DMA_STAT                0x30

/*
 * sun8i specific registers
 */
#define SUN8I_DMA_GATE          0x20
#define SUN8I_DMA_GATE_ENABLE   0x4

/*
 * Channels specific registers
 */
#define DMA_CHAN_ENABLE         0x00
#define DMA_CHAN_ENABLE_START           BIT(0)
#define DMA_CHAN_ENABLE_STOP            0

#define DMA_CHAN_PAUSE          0x04
#define DMA_CHAN_PAUSE_PAUSE            BIT(1)
#define DMA_CHAN_PAUSE_RESUME           0

#define DMA_CHAN_LLI_ADDR       0x08

#define DMA_CHAN_CUR_CFG        0x0c
#define DMA_CHAN_CFG_SRC_DRQ(x)         ((x) & 0x1f)
#define DMA_CHAN_CFG_SRC_IO_MODE        BIT(5)
#define DMA_CHAN_CFG_SRC_LINEAR_MODE    (0 << 5)
#define DMA_CHAN_CFG_SRC_BURST(x)       (((x) & 0x3) << 7)
#define DMA_CHAN_CFG_SRC_WIDTH(x)       (((x) & 0x3) << 9)

#define DMA_CHAN_CFG_DST_DRQ(x)         (DMA_CHAN_CFG_SRC_DRQ(x) << 16)
#define DMA_CHAN_CFG_DST_IO_MODE        (DMA_CHAN_CFG_SRC_IO_MODE << 16)
#define DMA_CHAN_CFG_DST_LINEAR_MODE    (DMA_CHAN_CFG_SRC_LINEAR_MODE << 16)
#define DMA_CHAN_CFG_DST_BURST(x)       (DMA_CHAN_CFG_SRC_BURST(x) << 16)
#define DMA_CHAN_CFG_DST_WIDTH(x)       (DMA_CHAN_CFG_SRC_WIDTH(x) << 16)

#define DMA_CHAN_CUR_SRC        0x10

#define DMA_CHAN_CUR_DST        0x14

#define DMA_CHAN_CUR_CNT        0x18

#define DMA_CHAN_CUR_PARA       0x1c


/*
 * Various hardware related defines
 */
#define LLI_LAST_ITEM   0xfffff800
#define NORMAL_WAIT     8
#define DRQ_SDRAM       1

/*
 * Hardware channels / ports representation
 *
 * The hardware is used in several SoCs, with differing numbers
 * of channels and endpoints. This structure ties those numbers
 * to a certain compatible string.
 */
struct sun6i_dma_config {
        u32 nr_max_channels;
        u32 nr_max_requests;
        u32 nr_max_vchans;
        /*
         * In the datasheets/user manuals of newer Allwinner SoCs, a special
         * bit (bit 2 at register 0x20) is present.
         * It's named "DMA MCLK interface circuit auto gating bit" in the
         * documents, and the footnote of this register says that this bit
         * should be set up when initializing the DMA controller.
         * Allwinner A23/A33 user manuals do not have this bit documented,
         * however these SoCs really have and need this bit, as seen in the
         * BSP kernel source code.
         */
        bool gate_needed;
};

/*
 * Hardware representation of the LLI
 *
 * The hardware will be fed the physical address of this structure,
 * and read its content in order to start the transfer.
 */
struct sun6i_dma_lli {
        u32                     cfg;
        u32                     src;
        u32                     dst;
        u32                     len;
        u32                     para;
        u32                     p_lli_next;

        /*
         * This field is not used by the DMA controller, but will be
         * used by the CPU to go through the list (mostly for dumping
         * or freeing it).
         */
        struct sun6i_dma_lli    *v_lli_next;
};


struct sun6i_desc {
        struct virt_dma_desc    vd;
        dma_addr_t              p_lli;
        struct sun6i_dma_lli    *v_lli;
};

struct sun6i_pchan {
        u32                     idx;
        void __iomem            *base;
        struct sun6i_vchan      *vchan;
        struct sun6i_desc       *desc;
        struct sun6i_desc       *done;
};

struct sun6i_vchan {
        struct virt_dma_chan    vc;
        struct list_head        node;
        struct dma_slave_config cfg;
        struct sun6i_pchan      *phy;
        u8                      port;
        u8                      irq_type;
        bool                    cyclic;
};

struct sun6i_dma_dev {
        struct dma_device       slave;
        void __iomem            *base;
        struct clk              *clk;
        int                     irq;
        spinlock_t              lock;
        struct reset_control    *rstc;
        struct tasklet_struct   task;
        atomic_t                tasklet_shutdown;
        struct list_head        pending;
        struct dma_pool         *pool;
        struct sun6i_pchan      *pchans;
        struct sun6i_vchan      *vchans;
        const struct sun6i_dma_config *cfg;
};

static struct device *chan2dev(struct dma_chan *chan)
{
        return &chan->dev->device;
}

static inline struct sun6i_dma_dev *to_sun6i_dma_dev(struct dma_device *d)
{
        return container_of(d, struct sun6i_dma_dev, slave);
}

static inline struct sun6i_vchan *to_sun6i_vchan(struct dma_chan *chan)
{
        return container_of(chan, struct sun6i_vchan, vc.chan);
}

static inline struct sun6i_desc *
to_sun6i_desc(struct dma_async_tx_descriptor *tx)
{
        return container_of(tx, struct sun6i_desc, vd.tx);
}

static inline void sun6i_dma_dump_com_regs(struct sun6i_dma_dev *sdev)
{
        dev_dbg(sdev->slave.dev, "Common register:\n"
                "\tmask0(%04x): 0x%08x\n"
                "\tmask1(%04x): 0x%08x\n"
                "\tpend0(%04x): 0x%08x\n"
                "\tpend1(%04x): 0x%08x\n"
                "\tstats(%04x): 0x%08x\n",
                DMA_IRQ_EN(0), readl(sdev->base + DMA_IRQ_EN(0)),
                DMA_IRQ_EN(1), readl(sdev->base + DMA_IRQ_EN(1)),
                DMA_IRQ_STAT(0), readl(sdev->base + DMA_IRQ_STAT(0)),
                DMA_IRQ_STAT(1), readl(sdev->base + DMA_IRQ_STAT(1)),
                DMA_STAT, readl(sdev->base + DMA_STAT));
}

static inline void sun6i_dma_dump_chan_regs(struct sun6i_dma_dev *sdev,
                                            struct sun6i_pchan *pchan)
{
        phys_addr_t reg = virt_to_phys(pchan->base);

        dev_dbg(sdev->slave.dev, "Chan %d reg: %pa\n"
                "\t___en(%04x): \t0x%08x\n"
                "\tpause(%04x): \t0x%08x\n"
                "\tstart(%04x): \t0x%08x\n"
                "\t__cfg(%04x): \t0x%08x\n"
                "\t__src(%04x): \t0x%08x\n"
                "\t__dst(%04x): \t0x%08x\n"
                "\tcount(%04x): \t0x%08x\n"
                "\t_para(%04x): \t0x%08x\n\n",
                pchan->idx, &reg,
                DMA_CHAN_ENABLE,
                readl(pchan->base + DMA_CHAN_ENABLE),
                DMA_CHAN_PAUSE,
                readl(pchan->base + DMA_CHAN_PAUSE),
                DMA_CHAN_LLI_ADDR,
                readl(pchan->base + DMA_CHAN_LLI_ADDR),
                DMA_CHAN_CUR_CFG,
                readl(pchan->base + DMA_CHAN_CUR_CFG),
                DMA_CHAN_CUR_SRC,
                readl(pchan->base + DMA_CHAN_CUR_SRC),
                DMA_CHAN_CUR_DST,
                readl(pchan->base + DMA_CHAN_CUR_DST),
                DMA_CHAN_CUR_CNT,
                readl(pchan->base + DMA_CHAN_CUR_CNT),
                DMA_CHAN_CUR_PARA,
                readl(pchan->base + DMA_CHAN_CUR_PARA));
}

static inline s8 convert_burst(u32 maxburst)
{
        switch (maxburst) {
        case 1:
                return 0;
        case 8:
                return 2;
        default:
                return -EINVAL;
        }
}

static inline s8 convert_buswidth(enum dma_slave_buswidth addr_width)
{
        if ((addr_width < DMA_SLAVE_BUSWIDTH_1_BYTE) ||
            (addr_width > DMA_SLAVE_BUSWIDTH_4_BYTES))
                return -EINVAL;

        return addr_width >> 1;
}

static size_t sun6i_get_chan_size(struct sun6i_pchan *pchan)
{
        struct sun6i_desc *txd = pchan->desc;
        struct sun6i_dma_lli *lli;
        size_t bytes;
        dma_addr_t pos;

        pos = readl(pchan->base + DMA_CHAN_LLI_ADDR);
        bytes = readl(pchan->base + DMA_CHAN_CUR_CNT);

        if (pos == LLI_LAST_ITEM)
                return bytes;

        for (lli = txd->v_lli; lli; lli = lli->v_lli_next) {
                if (lli->p_lli_next == pos) {
                        for (lli = lli->v_lli_next; lli; lli = lli->v_lli_next)
                                bytes += lli->len;
                        break;
                }
        }

        return bytes;
}

static void *sun6i_dma_lli_add(struct sun6i_dma_lli *prev,
                               struct sun6i_dma_lli *next,
                               dma_addr_t next_phy,
                               struct sun6i_desc *txd)
{
        if ((!prev && !txd) || !next)
                return NULL;

        if (!prev) {
                txd->p_lli = next_phy;
                txd->v_lli = next;
        } else {
                prev->p_lli_next = next_phy;
                prev->v_lli_next = next;
        }

        next->p_lli_next = LLI_LAST_ITEM;
        next->v_lli_next = NULL;

        return next;
}

static inline void sun6i_dma_dump_lli(struct sun6i_vchan *vchan,
                                      struct sun6i_dma_lli *lli)
{
        phys_addr_t p_lli = virt_to_phys(lli);

        dev_dbg(chan2dev(&vchan->vc.chan),
                "\n\tdesc:   p - %pa v - 0x%p\n"
                "\t\tc - 0x%08x s - 0x%08x d - 0x%08x\n"
                "\t\tl - 0x%08x p - 0x%08x n - 0x%08x\n",
                &p_lli, lli,
                lli->cfg, lli->src, lli->dst,
                lli->len, lli->para, lli->p_lli_next);
}

static void sun6i_dma_free_desc(struct virt_dma_desc *vd)
{
        struct sun6i_desc *txd = to_sun6i_desc(&vd->tx);
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device);
        struct sun6i_dma_lli *v_lli, *v_next;
        dma_addr_t p_lli, p_next;

        if (unlikely(!txd))
                return;

        p_lli = txd->p_lli;
        v_lli = txd->v_lli;

        while (v_lli) {
                v_next = v_lli->v_lli_next;
                p_next = v_lli->p_lli_next;

                dma_pool_free(sdev->pool, v_lli, p_lli);

                v_lli = v_next;
                p_lli = p_next;
        }

        kfree(txd);
}

static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
        struct virt_dma_desc *desc = vchan_next_desc(&vchan->vc);
        struct sun6i_pchan *pchan = vchan->phy;
        u32 irq_val, irq_reg, irq_offset;

        if (!pchan)
                return -EAGAIN;

        if (!desc) {
                pchan->desc = NULL;
                pchan->done = NULL;
                return -EAGAIN;
        }

        list_del(&desc->node);

        pchan->desc = to_sun6i_desc(&desc->tx);
        pchan->done = NULL;

        sun6i_dma_dump_lli(vchan, pchan->desc->v_lli);

        irq_reg = pchan->idx / DMA_IRQ_CHAN_NR;
        irq_offset = pchan->idx % DMA_IRQ_CHAN_NR;

        vchan->irq_type = vchan->cyclic ? DMA_IRQ_PKG : DMA_IRQ_QUEUE;

        irq_val = readl(sdev->base + DMA_IRQ_EN(irq_reg));
        irq_val &= ~((DMA_IRQ_HALF | DMA_IRQ_PKG | DMA_IRQ_QUEUE) <<
                        (irq_offset * DMA_IRQ_CHAN_WIDTH));
        irq_val |= vchan->irq_type << (irq_offset * DMA_IRQ_CHAN_WIDTH);
        writel(irq_val, sdev->base + DMA_IRQ_EN(irq_reg));

        writel(pchan->desc->p_lli, pchan->base + DMA_CHAN_LLI_ADDR);
        writel(DMA_CHAN_ENABLE_START, pchan->base + DMA_CHAN_ENABLE);

        sun6i_dma_dump_com_regs(sdev);
        sun6i_dma_dump_chan_regs(sdev, pchan);

        return 0;
}

static void sun6i_dma_tasklet(unsigned long data)
{
        struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)data;
        const struct sun6i_dma_config *cfg = sdev->cfg;
        struct sun6i_vchan *vchan;
        struct sun6i_pchan *pchan;
        unsigned int pchan_alloc = 0;
        unsigned int pchan_idx;

        list_for_each_entry(vchan, &sdev->slave.channels, vc.chan.device_node) {
                spin_lock_irq(&vchan->vc.lock);

                pchan = vchan->phy;

                if (pchan && pchan->done) {
                        if (sun6i_dma_start_desc(vchan)) {
                                /*
                                 * No current txd associated with this channel
                                 */
                                dev_dbg(sdev->slave.dev, "pchan %u: free\n",
                                        pchan->idx);

                                /* Mark this channel free */
                                vchan->phy = NULL;
                                pchan->vchan = NULL;
                        }
                }
                spin_unlock_irq(&vchan->vc.lock);
        }

        spin_lock_irq(&sdev->lock);
        for (pchan_idx = 0; pchan_idx < cfg->nr_max_channels; pchan_idx++) {
                pchan = &sdev->pchans[pchan_idx];

                if (pchan->vchan || list_empty(&sdev->pending))
                        continue;

                vchan = list_first_entry(&sdev->pending,
                                         struct sun6i_vchan, node);

                /* Remove from pending channels */
                list_del_init(&vchan->node);
                pchan_alloc |= BIT(pchan_idx);

                /* Mark this channel allocated */
                pchan->vchan = vchan;
                vchan->phy = pchan;
                dev_dbg(sdev->slave.dev, "pchan %u: alloc vchan %p\n",
                        pchan->idx, &vchan->vc);
        }
        spin_unlock_irq(&sdev->lock);

        for (pchan_idx = 0; pchan_idx < cfg->nr_max_channels; pchan_idx++) {
                if (!(pchan_alloc & BIT(pchan_idx)))
                        continue;

                pchan = sdev->pchans + pchan_idx;
                vchan = pchan->vchan;
                if (vchan) {
                        spin_lock_irq(&vchan->vc.lock);
                        sun6i_dma_start_desc(vchan);
                        spin_unlock_irq(&vchan->vc.lock);
                }
        }
}

static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
{
        struct sun6i_dma_dev *sdev = dev_id;
        struct sun6i_vchan *vchan;
        struct sun6i_pchan *pchan;
        int i, j, ret = IRQ_NONE;
        u32 status;

        for (i = 0; i < sdev->cfg->nr_max_channels / DMA_IRQ_CHAN_NR; i++) {
                status = readl(sdev->base + DMA_IRQ_STAT(i));
                if (!status)
                        continue;

                dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
                        i ? "high" : "low", status);

                writel(status, sdev->base + DMA_IRQ_STAT(i));

                for (j = 0; (j < DMA_IRQ_CHAN_NR) && status; j++) {
                        pchan = sdev->pchans + j;
                        vchan = pchan->vchan;
                        if (vchan && (status & vchan->irq_type)) {
                                if (vchan->cyclic) {
                                        vchan_cyclic_callback(&pchan->desc->vd);
                                } else {
                                        spin_lock(&vchan->vc.lock);
                                        vchan_cookie_complete(&pchan->desc->vd);
                                        pchan->done = pchan->desc;
                                        spin_unlock(&vchan->vc.lock);
                                }
                        }

                        status = status >> DMA_IRQ_CHAN_WIDTH;
                }

                if (!atomic_read(&sdev->tasklet_shutdown))
                        tasklet_schedule(&sdev->task);
                ret = IRQ_HANDLED;
        }

        return ret;
}

static int set_config(struct sun6i_dma_dev *sdev,
                        struct dma_slave_config *sconfig,
                        enum dma_transfer_direction direction,
                        u32 *p_cfg)
{
        s8 src_width, dst_width, src_burst, dst_burst;

        switch (direction) {
        case DMA_MEM_TO_DEV:
                src_burst = convert_burst(sconfig->src_maxburst ?
                                        sconfig->src_maxburst : 8);
                src_width = convert_buswidth(sconfig->src_addr_width !=
                                                DMA_SLAVE_BUSWIDTH_UNDEFINED ?
                                sconfig->src_addr_width :
                                DMA_SLAVE_BUSWIDTH_4_BYTES);
                dst_burst = convert_burst(sconfig->dst_maxburst);
                dst_width = convert_buswidth(sconfig->dst_addr_width);
                break;
        case DMA_DEV_TO_MEM:
                src_burst = convert_burst(sconfig->src_maxburst);
                src_width = convert_buswidth(sconfig->src_addr_width);
                dst_burst = convert_burst(sconfig->dst_maxburst ?
                                        sconfig->dst_maxburst : 8);
                dst_width = convert_buswidth(sconfig->dst_addr_width !=
                                                DMA_SLAVE_BUSWIDTH_UNDEFINED ?
                                sconfig->dst_addr_width :
                                DMA_SLAVE_BUSWIDTH_4_BYTES);
                break;
        default:
                return -EINVAL;
        }

        if (src_burst < 0)
                return src_burst;
        if (src_width < 0)
                return src_width;
        if (dst_burst < 0)
                return dst_burst;
        if (dst_width < 0)
                return dst_width;

        *p_cfg = DMA_CHAN_CFG_SRC_BURST(src_burst) |
                DMA_CHAN_CFG_SRC_WIDTH(src_width) |
                DMA_CHAN_CFG_DST_BURST(dst_burst) |
                DMA_CHAN_CFG_DST_WIDTH(dst_width);

        return 0;
}

static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_memcpy(
                struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                size_t len, unsigned long flags)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct sun6i_dma_lli *v_lli;
        struct sun6i_desc *txd;
        dma_addr_t p_lli;
        s8 burst, width;

        dev_dbg(chan2dev(chan),
                "%s; chan: %d, dest: %pad, src: %pad, len: %zu. flags: 0x%08lx\n",
                __func__, vchan->vc.chan.chan_id, &dest, &src, len, flags);

        if (!len)
                return NULL;

        txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
        if (!txd)
                return NULL;

        v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
        if (!v_lli) {
                dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
                goto err_txd_free;
        }

        v_lli->src = src;
        v_lli->dst = dest;
        v_lli->len = len;
        v_lli->para = NORMAL_WAIT;

        burst = convert_burst(8);
        width = convert_buswidth(DMA_SLAVE_BUSWIDTH_4_BYTES);
        v_lli->cfg = DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
                DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
                DMA_CHAN_CFG_DST_LINEAR_MODE |
                DMA_CHAN_CFG_SRC_LINEAR_MODE |
                DMA_CHAN_CFG_SRC_BURST(burst) |
                DMA_CHAN_CFG_SRC_WIDTH(width) |
                DMA_CHAN_CFG_DST_BURST(burst) |
                DMA_CHAN_CFG_DST_WIDTH(width);

        sun6i_dma_lli_add(NULL, v_lli, p_lli, txd);

        sun6i_dma_dump_lli(vchan, v_lli);

        return vchan_tx_prep(&vchan->vc, &txd->vd, flags);

err_txd_free:
        kfree(txd);
        return NULL;
}

static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
                struct dma_chan *chan, struct scatterlist *sgl,
                unsigned int sg_len, enum dma_transfer_direction dir,
                unsigned long flags, void *context)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct dma_slave_config *sconfig = &vchan->cfg;
        struct sun6i_dma_lli *v_lli, *prev = NULL;
        struct sun6i_desc *txd;
        struct scatterlist *sg;
        dma_addr_t p_lli;
        u32 lli_cfg;
        int i, ret;

        if (!sgl)
                return NULL;

        ret = set_config(sdev, sconfig, dir, &lli_cfg);
        if (ret) {
                dev_err(chan2dev(chan), "Invalid DMA configuration\n");
                return NULL;
        }

        txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
        if (!txd)
                return NULL;

        for_each_sg(sgl, sg, sg_len, i) {
                v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
                if (!v_lli)
                        goto err_lli_free;

                v_lli->len = sg_dma_len(sg);
                v_lli->para = NORMAL_WAIT;

                if (dir == DMA_MEM_TO_DEV) {
                        v_lli->src = sg_dma_address(sg);
                        v_lli->dst = sconfig->dst_addr;
                        v_lli->cfg = lli_cfg |
                                DMA_CHAN_CFG_DST_IO_MODE |
                                DMA_CHAN_CFG_SRC_LINEAR_MODE |
                                DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
                                DMA_CHAN_CFG_DST_DRQ(vchan->port);

                        dev_dbg(chan2dev(chan),
                                "%s; chan: %d, dest: %pad, src: %pad, len: %u. flags: 0x%08lx\n",
                                __func__, vchan->vc.chan.chan_id,
                                &sconfig->dst_addr, &sg_dma_address(sg),
                                sg_dma_len(sg), flags);

                } else {
                        v_lli->src = sconfig->src_addr;
                        v_lli->dst = sg_dma_address(sg);
                        v_lli->cfg = lli_cfg |
                                DMA_CHAN_CFG_DST_LINEAR_MODE |
                                DMA_CHAN_CFG_SRC_IO_MODE |
                                DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
                                DMA_CHAN_CFG_SRC_DRQ(vchan->port);

                        dev_dbg(chan2dev(chan),
                                "%s; chan: %d, dest: %pad, src: %pad, len: %u. flags: 0x%08lx\n",
                                __func__, vchan->vc.chan.chan_id,
                                &sg_dma_address(sg), &sconfig->src_addr,
                                sg_dma_len(sg), flags);
                }

                prev = sun6i_dma_lli_add(prev, v_lli, p_lli, txd);
        }

        dev_dbg(chan2dev(chan), "First: %pad\n", &txd->p_lli);
        for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
                sun6i_dma_dump_lli(vchan, prev);

        return vchan_tx_prep(&vchan->vc, &txd->vd, flags);

err_lli_free:
        for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
                dma_pool_free(sdev->pool, prev, virt_to_phys(prev));
        kfree(txd);
        return NULL;
}

static struct dma_async_tx_descriptor *sun6i_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 sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct dma_slave_config *sconfig = &vchan->cfg;
        struct sun6i_dma_lli *v_lli, *prev = NULL;
        struct sun6i_desc *txd;
        dma_addr_t p_lli;
        u32 lli_cfg;
        unsigned int i, periods = buf_len / period_len;
        int ret;

        ret = set_config(sdev, sconfig, dir, &lli_cfg);
        if (ret) {
                dev_err(chan2dev(chan), "Invalid DMA configuration\n");
                return NULL;
        }

        txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
        if (!txd)
                return NULL;

        for (i = 0; i < periods; i++) {
                v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
                if (!v_lli) {
                        dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
                        goto err_lli_free;
                }

                v_lli->len = period_len;
                v_lli->para = NORMAL_WAIT;

                if (dir == DMA_MEM_TO_DEV) {
                        v_lli->src = buf_addr + period_len * i;
                        v_lli->dst = sconfig->dst_addr;
                        v_lli->cfg = lli_cfg |
                                DMA_CHAN_CFG_DST_IO_MODE |
                                DMA_CHAN_CFG_SRC_LINEAR_MODE |
                                DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
                                DMA_CHAN_CFG_DST_DRQ(vchan->port);
                } else {
                        v_lli->src = sconfig->src_addr;
                        v_lli->dst = buf_addr + period_len * i;
                        v_lli->cfg = lli_cfg |
                                DMA_CHAN_CFG_DST_LINEAR_MODE |
                                DMA_CHAN_CFG_SRC_IO_MODE |
                                DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
                                DMA_CHAN_CFG_SRC_DRQ(vchan->port);
                }

                prev = sun6i_dma_lli_add(prev, v_lli, p_lli, txd);
        }

        prev->p_lli_next = txd->p_lli;          /* cyclic list */

        vchan->cyclic = true;

        return vchan_tx_prep(&vchan->vc, &txd->vd, flags);

err_lli_free:
        for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
                dma_pool_free(sdev->pool, prev, virt_to_phys(prev));
        kfree(txd);
        return NULL;
}

static int sun6i_dma_config(struct dma_chan *chan,
                            struct dma_slave_config *config)
{
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);

        memcpy(&vchan->cfg, config, sizeof(*config));

        return 0;
}

static int sun6i_dma_pause(struct dma_chan *chan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct sun6i_pchan *pchan = vchan->phy;

        dev_dbg(chan2dev(chan), "vchan %p: pause\n", &vchan->vc);

        if (pchan) {
                writel(DMA_CHAN_PAUSE_PAUSE,
                       pchan->base + DMA_CHAN_PAUSE);
        } else {
                spin_lock(&sdev->lock);
                list_del_init(&vchan->node);
                spin_unlock(&sdev->lock);
        }

        return 0;
}

static int sun6i_dma_resume(struct dma_chan *chan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct sun6i_pchan *pchan = vchan->phy;
        unsigned long flags;

        dev_dbg(chan2dev(chan), "vchan %p: resume\n", &vchan->vc);

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

        if (pchan) {
                writel(DMA_CHAN_PAUSE_RESUME,
                       pchan->base + DMA_CHAN_PAUSE);
        } else if (!list_empty(&vchan->vc.desc_issued)) {
                spin_lock(&sdev->lock);
                list_add_tail(&vchan->node, &sdev->pending);
                spin_unlock(&sdev->lock);
        }

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

        return 0;
}

static int sun6i_dma_terminate_all(struct dma_chan *chan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct sun6i_pchan *pchan = vchan->phy;
        unsigned long flags;
        LIST_HEAD(head);

        spin_lock(&sdev->lock);
        list_del_init(&vchan->node);
        spin_unlock(&sdev->lock);

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

        if (vchan->cyclic) {
                vchan->cyclic = false;
                if (pchan && pchan->desc) {
                        struct virt_dma_desc *vd = &pchan->desc->vd;
                        struct virt_dma_chan *vc = &vchan->vc;

                        list_add_tail(&vd->node, &vc->desc_completed);
                }
        }

        vchan_get_all_descriptors(&vchan->vc, &head);

        if (pchan) {
                writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
                writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);

                vchan->phy = NULL;
                pchan->vchan = NULL;
                pchan->desc = NULL;
                pchan->done = NULL;
        }

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

        vchan_dma_desc_free_list(&vchan->vc, &head);

        return 0;
}

static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan,
                                           dma_cookie_t cookie,
                                           struct dma_tx_state *state)
{
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        struct sun6i_pchan *pchan = vchan->phy;
        struct sun6i_dma_lli *lli;
        struct virt_dma_desc *vd;
        struct sun6i_desc *txd;
        enum dma_status ret;
        unsigned long flags;
        size_t bytes = 0;

        ret = dma_cookie_status(chan, cookie, state);
        if (ret == DMA_COMPLETE || !state)
                return ret;

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

        vd = vchan_find_desc(&vchan->vc, cookie);
        txd = to_sun6i_desc(&vd->tx);

        if (vd) {
                for (lli = txd->v_lli; lli != NULL; lli = lli->v_lli_next)
                        bytes += lli->len;
        } else if (!pchan || !pchan->desc) {
                bytes = 0;
        } else {
                bytes = sun6i_get_chan_size(pchan);
        }

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

        dma_set_residue(state, bytes);

        return ret;
}

static void sun6i_dma_issue_pending(struct dma_chan *chan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        unsigned long flags;

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

        if (vchan_issue_pending(&vchan->vc)) {
                spin_lock(&sdev->lock);

                if (!vchan->phy && list_empty(&vchan->node)) {
                        list_add_tail(&vchan->node, &sdev->pending);
                        tasklet_schedule(&sdev->task);
                        dev_dbg(chan2dev(chan), "vchan %p: issued\n",
                                &vchan->vc);
                }

                spin_unlock(&sdev->lock);
        } else {
                dev_dbg(chan2dev(chan), "vchan %p: nothing to issue\n",
                        &vchan->vc);
        }

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

static void sun6i_dma_free_chan_resources(struct dma_chan *chan)
{
        struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
        struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
        unsigned long flags;

        spin_lock_irqsave(&sdev->lock, flags);
        list_del_init(&vchan->node);
        spin_unlock_irqrestore(&sdev->lock, flags);

        vchan_free_chan_resources(&vchan->vc);
}

static struct dma_chan *sun6i_dma_of_xlate(struct of_phandle_args *dma_spec,
                                           struct of_dma *ofdma)
{
        struct sun6i_dma_dev *sdev = ofdma->of_dma_data;
        struct sun6i_vchan *vchan;
        struct dma_chan *chan;
        u8 port = dma_spec->args[0];

        if (port > sdev->cfg->nr_max_requests)
                return NULL;

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

        vchan = to_sun6i_vchan(chan);
        vchan->port = port;

        return chan;
}

static inline void sun6i_kill_tasklet(struct sun6i_dma_dev *sdev)
{
        /* Disable all interrupts from DMA */
        writel(0, sdev->base + DMA_IRQ_EN(0));
        writel(0, sdev->base + DMA_IRQ_EN(1));

        /* Prevent spurious interrupts from scheduling the tasklet */
        atomic_inc(&sdev->tasklet_shutdown);

        /* Make sure we won't have any further interrupts */
        devm_free_irq(sdev->slave.dev, sdev->irq, sdev);

        /* Actually prevent the tasklet from being scheduled */
        tasklet_kill(&sdev->task);
}

static inline void sun6i_dma_free(struct sun6i_dma_dev *sdev)
{
        int i;

        for (i = 0; i < sdev->cfg->nr_max_vchans; i++) {
                struct sun6i_vchan *vchan = &sdev->vchans[i];

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

/*
 * For A31:
 *
 * There's 16 physical channels that can work in parallel.
 *
 * However we have 30 different endpoints for our requests.
 *
 * Since the channels are able to handle only an unidirectional
 * transfer, we need to allocate more virtual channels so that

 * everyone can grab one channel.
 *
 * Some devices can't work in both direction (mostly because it
 * wouldn't make sense), so we have a bit fewer virtual channels than
 * 2 channels per endpoints.
 */

static struct sun6i_dma_config sun6i_a31_dma_cfg = {
        .nr_max_channels = 16,
        .nr_max_requests = 30,
        .nr_max_vchans   = 53,
};

/*
 * The A23 only has 8 physical channels, a maximum DRQ port id of 24,
 * and a total of 37 usable source and destination endpoints.
 */

static struct sun6i_dma_config sun8i_a23_dma_cfg = {
        .nr_max_channels = 8,
        .nr_max_requests = 24,
        .nr_max_vchans   = 37,
        .gate_needed     = true,
};

static struct sun6i_dma_config sun8i_a83t_dma_cfg = {
        .nr_max_channels = 8,
        .nr_max_requests = 28,
        .nr_max_vchans   = 39,
};

/*
 * The H3 has 12 physical channels, a maximum DRQ port id of 27,
 * and a total of 34 usable source and destination endpoints.
 */

static struct sun6i_dma_config sun8i_h3_dma_cfg = {
        .nr_max_channels = 12,
        .nr_max_requests = 27,
        .nr_max_vchans   = 34,
};

/*
 * The V3s have only 8 physical channels, a maximum DRQ port id of 23,
 * and a total of 24 usable source and destination endpoints.
 */

static struct sun6i_dma_config sun8i_v3s_dma_cfg = {
        .nr_max_channels = 8,
        .nr_max_requests = 23,
        .nr_max_vchans   = 24,
        .gate_needed     = true,
};

static const struct of_device_id sun6i_dma_match[] = {
        { .compatible = "allwinner,sun6i-a31-dma", .data = &sun6i_a31_dma_cfg },
        { .compatible = "allwinner,sun8i-a23-dma", .data = &sun8i_a23_dma_cfg },
        { .compatible = "allwinner,sun8i-a83t-dma", .data = &sun8i_a83t_dma_cfg },
        { .compatible = "allwinner,sun8i-h3-dma", .data = &sun8i_h3_dma_cfg },
        { .compatible = "allwinner,sun8i-v3s-dma", .data = &sun8i_v3s_dma_cfg },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sun6i_dma_match);

static int sun6i_dma_probe(struct platform_device *pdev)
{
        const struct of_device_id *device;
        struct sun6i_dma_dev *sdc;
        struct resource *res;
        int ret, i;

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

        device = of_match_device(sun6i_dma_match, &pdev->dev);
        if (!device)
                return -ENODEV;
        sdc->cfg = device->data;

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

        sdc->irq = platform_get_irq(pdev, 0);
        if (sdc->irq < 0) {
                dev_err(&pdev->dev, "Cannot claim IRQ\n");
                return sdc->irq;
        }

        sdc->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(sdc->clk)) {
                dev_err(&pdev->dev, "No clock specified\n");
                return PTR_ERR(sdc->clk);
        }

        sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
        if (IS_ERR(sdc->rstc)) {
                dev_err(&pdev->dev, "No reset controller specified\n");
                return PTR_ERR(sdc->rstc);
        }

        sdc->pool = dmam_pool_create(dev_name(&pdev->dev), &pdev->dev,
                                     sizeof(struct sun6i_dma_lli), 4, 0);
        if (!sdc->pool) {
                dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
                return -ENOMEM;
        }

        platform_set_drvdata(pdev, sdc);
        INIT_LIST_HEAD(&sdc->pending);
        spin_lock_init(&sdc->lock);

        dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask);
        dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask);
        dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask);
        dma_cap_set(DMA_CYCLIC, sdc->slave.cap_mask);

        INIT_LIST_HEAD(&sdc->slave.channels);
        sdc->slave.device_free_chan_resources   = sun6i_dma_free_chan_resources;
        sdc->slave.device_tx_status             = sun6i_dma_tx_status;
        sdc->slave.device_issue_pending         = sun6i_dma_issue_pending;
        sdc->slave.device_prep_slave_sg         = sun6i_dma_prep_slave_sg;
        sdc->slave.device_prep_dma_memcpy       = sun6i_dma_prep_dma_memcpy;
        sdc->slave.device_prep_dma_cyclic       = sun6i_dma_prep_dma_cyclic;
        sdc->slave.copy_align                   = DMAENGINE_ALIGN_4_BYTES;
        sdc->slave.device_config                = sun6i_dma_config;
        sdc->slave.device_pause                 = sun6i_dma_pause;
        sdc->slave.device_resume                = sun6i_dma_resume;
        sdc->slave.device_terminate_all         = sun6i_dma_terminate_all;
        sdc->slave.src_addr_widths              = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
                                                  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
                                                  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
        sdc->slave.dst_addr_widths              = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
                                                  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
                                                  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
        sdc->slave.directions                   = BIT(DMA_DEV_TO_MEM) |
                                                  BIT(DMA_MEM_TO_DEV);
        sdc->slave.residue_granularity          = DMA_RESIDUE_GRANULARITY_BURST;
        sdc->slave.dev = &pdev->dev;

        sdc->pchans = devm_kcalloc(&pdev->dev, sdc->cfg->nr_max_channels,
                                   sizeof(struct sun6i_pchan), GFP_KERNEL);
        if (!sdc->pchans)
                return -ENOMEM;

        sdc->vchans = devm_kcalloc(&pdev->dev, sdc->cfg->nr_max_vchans,
                                   sizeof(struct sun6i_vchan), GFP_KERNEL);
        if (!sdc->vchans)
                return -ENOMEM;

        tasklet_init(&sdc->task, sun6i_dma_tasklet, (unsigned long)sdc);

        for (i = 0; i < sdc->cfg->nr_max_channels; i++) {
                struct sun6i_pchan *pchan = &sdc->pchans[i];

                pchan->idx = i;
                pchan->base = sdc->base + 0x100 + i * 0x40;
        }

        for (i = 0; i < sdc->cfg->nr_max_vchans; i++) {
                struct sun6i_vchan *vchan = &sdc->vchans[i];

                INIT_LIST_HEAD(&vchan->node);
                vchan->vc.desc_free = sun6i_dma_free_desc;
                vchan_init(&vchan->vc, &sdc->slave);
        }

        ret = reset_control_deassert(sdc->rstc);
        if (ret) {
                dev_err(&pdev->dev, "Couldn't deassert the device from reset\n");
                goto err_chan_free;
        }

        ret = clk_prepare_enable(sdc->clk);
        if (ret) {
                dev_err(&pdev->dev, "Couldn't enable the clock\n");
                goto err_reset_assert;
        }

        ret = devm_request_irq(&pdev->dev, sdc->irq, sun6i_dma_interrupt, 0,
                               dev_name(&pdev->dev), sdc);
        if (ret) {
                dev_err(&pdev->dev, "Cannot request IRQ\n");
                goto err_clk_disable;
        }

        ret = dma_async_device_register(&sdc->slave);
        if (ret) {
                dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
                goto err_irq_disable;
        }

        ret = of_dma_controller_register(pdev->dev.of_node, sun6i_dma_of_xlate,
                                         sdc);
        if (ret) {
                dev_err(&pdev->dev, "of_dma_controller_register failed\n");
                goto err_dma_unregister;
        }

        if (sdc->cfg->gate_needed)
                writel(SUN8I_DMA_GATE_ENABLE, sdc->base + SUN8I_DMA_GATE);

        return 0;

err_dma_unregister:
        dma_async_device_unregister(&sdc->slave);
err_irq_disable:
        sun6i_kill_tasklet(sdc);
err_clk_disable:
        clk_disable_unprepare(sdc->clk);
err_reset_assert:
        reset_control_assert(sdc->rstc);
err_chan_free:
        sun6i_dma_free(sdc);
        return ret;
}

static int sun6i_dma_remove(struct platform_device *pdev)
{
        struct sun6i_dma_dev *sdc = platform_get_drvdata(pdev);

        of_dma_controller_free(pdev->dev.of_node);
        dma_async_device_unregister(&sdc->slave);

        sun6i_kill_tasklet(sdc);

        clk_disable_unprepare(sdc->clk);
        reset_control_assert(sdc->rstc);

        sun6i_dma_free(sdc);

        return 0;
}

static struct platform_driver sun6i_dma_driver = {
        .probe          = sun6i_dma_probe,
        .remove         = sun6i_dma_remove,
        .driver = {
                .name           = "sun6i-dma",
                .of_match_table = sun6i_dma_match,
        },
};
module_platform_driver(sun6i_dma_driver);

MODULE_DESCRIPTION("Allwinner A31 DMA Controller Driver");
MODULE_AUTHOR("Sugar <shuge@allwinnertech.com>");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_LICENSE("GPL");