// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018-2019 MediaTek Inc.

/*
 * Driver for MediaTek Command-Queue DMA Controller
 *
 * Author: Shun-Chih Yu <shun-chih.yu@mediatek.com>
 *
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/iopoll.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/refcount.h>
#include <linux/slab.h>

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

#define MTK_CQDMA_USEC_POLL             10
#define MTK_CQDMA_TIMEOUT_POLL          1000
#define MTK_CQDMA_DMA_BUSWIDTHS         BIT(DMA_SLAVE_BUSWIDTH_4_BYTES)
#define MTK_CQDMA_ALIGN_SIZE            1

/* The default number of virtual channel */
#define MTK_CQDMA_NR_VCHANS             32

/* The default number of physical channel */
#define MTK_CQDMA_NR_PCHANS             3

/* Registers for underlying dma manipulation */
#define MTK_CQDMA_INT_FLAG              0x0
#define MTK_CQDMA_INT_EN                0x4
#define MTK_CQDMA_EN                    0x8
#define MTK_CQDMA_RESET                 0xc
#define MTK_CQDMA_FLUSH                 0x14
#define MTK_CQDMA_SRC                   0x1c
#define MTK_CQDMA_DST                   0x20
#define MTK_CQDMA_LEN1                  0x24
#define MTK_CQDMA_LEN2                  0x28
#define MTK_CQDMA_SRC2                  0x60
#define MTK_CQDMA_DST2                  0x64

/* Registers setting */
#define MTK_CQDMA_EN_BIT                BIT(0)
#define MTK_CQDMA_INT_FLAG_BIT          BIT(0)
#define MTK_CQDMA_INT_EN_BIT            BIT(0)
#define MTK_CQDMA_FLUSH_BIT             BIT(0)

#define MTK_CQDMA_WARM_RST_BIT          BIT(0)
#define MTK_CQDMA_HARD_RST_BIT          BIT(1)

#define MTK_CQDMA_MAX_LEN               GENMASK(27, 0)
#define MTK_CQDMA_ADDR_LIMIT            GENMASK(31, 0)
#define MTK_CQDMA_ADDR2_SHFIT           (32)

/**
 * struct mtk_cqdma_vdesc - The struct holding info describing virtual
 *                         descriptor (CVD)
 * @vd:                    An instance for struct virt_dma_desc
 * @len:                   The total data size device wants to move
 * @residue:               The remaining data size device will move
 * @dest:                  The destination address device wants to move to
 * @src:                   The source address device wants to move from
 * @ch:                    The pointer to the corresponding dma channel
 * @node:                  The lise_head struct to build link-list for VDs
 * @parent:                The pointer to the parent CVD
 */
struct mtk_cqdma_vdesc {
        struct virt_dma_desc vd;
        size_t len;
        size_t residue;
        dma_addr_t dest;
        dma_addr_t src;
        struct dma_chan *ch;

        struct list_head node;
        struct mtk_cqdma_vdesc *parent;
};

/**
 * struct mtk_cqdma_pchan - The struct holding info describing physical
 *                         channel (PC)
 * @queue:                 Queue for the PDs issued to this PC
 * @base:                  The mapped register I/O base of this PC
 * @irq:                   The IRQ that this PC are using
 * @refcnt:                Track how many VCs are using this PC
 * @tasklet:               Tasklet for this PC
 * @lock:                  Lock protect agaisting multiple VCs access PC
 */
struct mtk_cqdma_pchan {
        struct list_head queue;
        void __iomem *base;
        u32 irq;

        refcount_t refcnt;

        struct tasklet_struct tasklet;

        /* lock to protect PC */
        spinlock_t lock;
};

/**
 * struct mtk_cqdma_vchan - The struct holding info describing virtual
 *                         channel (VC)
 * @vc:                    An instance for struct virt_dma_chan
 * @pc:                    The pointer to the underlying PC
 * @issue_completion:      The wait for all issued descriptors completited
 * @issue_synchronize:     Bool indicating channel synchronization starts
 */
struct mtk_cqdma_vchan {
        struct virt_dma_chan vc;
        struct mtk_cqdma_pchan *pc;
        struct completion issue_completion;
        bool issue_synchronize;
};

/**
 * struct mtk_cqdma_device - The struct holding info describing CQDMA
 *                          device
 * @ddev:                   An instance for struct dma_device
 * @clk:                    The clock that device internal is using
 * @dma_requests:           The number of VCs the device supports to
 * @dma_channels:           The number of PCs the device supports to
 * @vc:                     The pointer to all available VCs
 * @pc:                     The pointer to all the underlying PCs
 */
struct mtk_cqdma_device {
        struct dma_device ddev;
        struct clk *clk;

        u32 dma_requests;
        u32 dma_channels;
        struct mtk_cqdma_vchan *vc;
        struct mtk_cqdma_pchan **pc;
};

static struct mtk_cqdma_device *to_cqdma_dev(struct dma_chan *chan)
{
        return container_of(chan->device, struct mtk_cqdma_device, ddev);
}

static struct mtk_cqdma_vchan *to_cqdma_vchan(struct dma_chan *chan)
{
        return container_of(chan, struct mtk_cqdma_vchan, vc.chan);
}

static struct mtk_cqdma_vdesc *to_cqdma_vdesc(struct virt_dma_desc *vd)
{
        return container_of(vd, struct mtk_cqdma_vdesc, vd);
}

static struct device *cqdma2dev(struct mtk_cqdma_device *cqdma)
{
        return cqdma->ddev.dev;
}

static u32 mtk_dma_read(struct mtk_cqdma_pchan *pc, u32 reg)
{
        return readl(pc->base + reg);
}

static void mtk_dma_write(struct mtk_cqdma_pchan *pc, u32 reg, u32 val)
{
        writel_relaxed(val, pc->base + reg);
}

static void mtk_dma_rmw(struct mtk_cqdma_pchan *pc, u32 reg,
                        u32 mask, u32 set)
{
        u32 val;

        val = mtk_dma_read(pc, reg);
        val &= ~mask;
        val |= set;
        mtk_dma_write(pc, reg, val);
}

static void mtk_dma_set(struct mtk_cqdma_pchan *pc, u32 reg, u32 val)
{
        mtk_dma_rmw(pc, reg, 0, val);
}

static void mtk_dma_clr(struct mtk_cqdma_pchan *pc, u32 reg, u32 val)
{
        mtk_dma_rmw(pc, reg, val, 0);
}

static void mtk_cqdma_vdesc_free(struct virt_dma_desc *vd)
{
        kfree(to_cqdma_vdesc(vd));
}

static int mtk_cqdma_poll_engine_done(struct mtk_cqdma_pchan *pc, bool atomic)
{
        u32 status = 0;

        if (!atomic)
                return readl_poll_timeout(pc->base + MTK_CQDMA_EN,
                                          status,
                                          !(status & MTK_CQDMA_EN_BIT),
                                          MTK_CQDMA_USEC_POLL,
                                          MTK_CQDMA_TIMEOUT_POLL);

        return readl_poll_timeout_atomic(pc->base + MTK_CQDMA_EN,
                                         status,
                                         !(status & MTK_CQDMA_EN_BIT),
                                         MTK_CQDMA_USEC_POLL,
                                         MTK_CQDMA_TIMEOUT_POLL);
}

static int mtk_cqdma_hard_reset(struct mtk_cqdma_pchan *pc)
{
        mtk_dma_set(pc, MTK_CQDMA_RESET, MTK_CQDMA_HARD_RST_BIT);
        mtk_dma_clr(pc, MTK_CQDMA_RESET, MTK_CQDMA_HARD_RST_BIT);

        return mtk_cqdma_poll_engine_done(pc, true);
}

static void mtk_cqdma_start(struct mtk_cqdma_pchan *pc,
                            struct mtk_cqdma_vdesc *cvd)
{
        /* wait for the previous transaction done */
        if (mtk_cqdma_poll_engine_done(pc, true) < 0)
                dev_err(cqdma2dev(to_cqdma_dev(cvd->ch)), "cqdma wait transaction timeout\n");

        /* warm reset the dma engine for the new transaction */
        mtk_dma_set(pc, MTK_CQDMA_RESET, MTK_CQDMA_WARM_RST_BIT);
        if (mtk_cqdma_poll_engine_done(pc, true) < 0)
                dev_err(cqdma2dev(to_cqdma_dev(cvd->ch)), "cqdma warm reset timeout\n");

        /* setup the source */
        mtk_dma_set(pc, MTK_CQDMA_SRC, cvd->src & MTK_CQDMA_ADDR_LIMIT);
#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
        mtk_dma_set(pc, MTK_CQDMA_SRC2, cvd->src >> MTK_CQDMA_ADDR2_SHFIT);
#else
        mtk_dma_set(pc, MTK_CQDMA_SRC2, 0);
#endif

        /* setup the destination */
        mtk_dma_set(pc, MTK_CQDMA_DST, cvd->dest & MTK_CQDMA_ADDR_LIMIT);
#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
        mtk_dma_set(pc, MTK_CQDMA_DST2, cvd->dest >> MTK_CQDMA_ADDR2_SHFIT);
#else
        mtk_dma_set(pc, MTK_CQDMA_DST2, 0);
#endif

        /* setup the length */
        mtk_dma_set(pc, MTK_CQDMA_LEN1, cvd->len);

        /* start dma engine */
        mtk_dma_set(pc, MTK_CQDMA_EN, MTK_CQDMA_EN_BIT);
}

static void mtk_cqdma_issue_vchan_pending(struct mtk_cqdma_vchan *cvc)
{
        struct virt_dma_desc *vd, *vd2;
        struct mtk_cqdma_pchan *pc = cvc->pc;
        struct mtk_cqdma_vdesc *cvd;
        bool trigger_engine = false;

        lockdep_assert_held(&cvc->vc.lock);
        lockdep_assert_held(&pc->lock);

        list_for_each_entry_safe(vd, vd2, &cvc->vc.desc_issued, node) {
                /* need to trigger dma engine if PC's queue is empty */
                if (list_empty(&pc->queue))
                        trigger_engine = true;

                cvd = to_cqdma_vdesc(vd);

                /* add VD into PC's queue */
                list_add_tail(&cvd->node, &pc->queue);

                /* start the dma engine */
                if (trigger_engine)
                        mtk_cqdma_start(pc, cvd);

                /* remove VD from list desc_issued */
                list_del(&vd->node);
        }
}

/*
 * return true if this VC is active,
 * meaning that there are VDs under processing by the PC
 */
static bool mtk_cqdma_is_vchan_active(struct mtk_cqdma_vchan *cvc)
{
        struct mtk_cqdma_vdesc *cvd;

        list_for_each_entry(cvd, &cvc->pc->queue, node)
                if (cvc == to_cqdma_vchan(cvd->ch))
                        return true;

        return false;
}

/*
 * return the pointer of the CVD that is just consumed by the PC
 */
static struct mtk_cqdma_vdesc
*mtk_cqdma_consume_work_queue(struct mtk_cqdma_pchan *pc)
{
        struct mtk_cqdma_vchan *cvc;
        struct mtk_cqdma_vdesc *cvd, *ret = NULL;

        /* consume a CVD from PC's queue */
        cvd = list_first_entry_or_null(&pc->queue,
                                       struct mtk_cqdma_vdesc, node);
        if (unlikely(!cvd || !cvd->parent))
                return NULL;

        cvc = to_cqdma_vchan(cvd->ch);
        ret = cvd;

        /* update residue of the parent CVD */
        cvd->parent->residue -= cvd->len;

        /* delete CVD from PC's queue */
        list_del(&cvd->node);

        spin_lock(&cvc->vc.lock);

        /* check whether all the child CVDs completed */
        if (!cvd->parent->residue) {
                /* add the parent VD into list desc_completed */
                vchan_cookie_complete(&cvd->parent->vd);

                /* setup completion if this VC is under synchronization */
                if (cvc->issue_synchronize && !mtk_cqdma_is_vchan_active(cvc)) {
                        complete(&cvc->issue_completion);
                        cvc->issue_synchronize = false;
                }
        }

        spin_unlock(&cvc->vc.lock);

        /* start transaction for next CVD in the queue */
        cvd = list_first_entry_or_null(&pc->queue,
                                       struct mtk_cqdma_vdesc, node);
        if (cvd)
                mtk_cqdma_start(pc, cvd);

        return ret;
}

static void mtk_cqdma_tasklet_cb(unsigned long data)
{
        struct mtk_cqdma_pchan *pc = (struct mtk_cqdma_pchan *)data;
        struct mtk_cqdma_vdesc *cvd = NULL;
        unsigned long flags;

        spin_lock_irqsave(&pc->lock, flags);
        /* consume the queue */
        cvd = mtk_cqdma_consume_work_queue(pc);
        spin_unlock_irqrestore(&pc->lock, flags);

        /* submit the next CVD */
        if (cvd) {
                dma_run_dependencies(&cvd->vd.tx);

                /*
                 * free child CVD after completion.
                 * the parent CVD would be freeed with desc_free by user.
                 */
                if (cvd->parent != cvd)
                        kfree(cvd);
        }

        /* re-enable interrupt before leaving tasklet */
        enable_irq(pc->irq);
}

static irqreturn_t mtk_cqdma_irq(int irq, void *devid)
{
        struct mtk_cqdma_device *cqdma = devid;
        irqreturn_t ret = IRQ_NONE;
        bool schedule_tasklet = false;
        u32 i;

        /* clear interrupt flags for each PC */
        for (i = 0; i < cqdma->dma_channels; ++i, schedule_tasklet = false) {
                spin_lock(&cqdma->pc[i]->lock);
                if (mtk_dma_read(cqdma->pc[i],
                                 MTK_CQDMA_INT_FLAG) & MTK_CQDMA_INT_FLAG_BIT) {
                        /* clear interrupt */
                        mtk_dma_clr(cqdma->pc[i], MTK_CQDMA_INT_FLAG,
                                    MTK_CQDMA_INT_FLAG_BIT);

                        schedule_tasklet = true;
                        ret = IRQ_HANDLED;
                }
                spin_unlock(&cqdma->pc[i]->lock);

                if (schedule_tasklet) {
                        /* disable interrupt */
                        disable_irq_nosync(cqdma->pc[i]->irq);

                        /* schedule the tasklet to handle the transactions */
                        tasklet_schedule(&cqdma->pc[i]->tasklet);
                }
        }

        return ret;
}

static struct virt_dma_desc *mtk_cqdma_find_active_desc(struct dma_chan *c,
                                                        dma_cookie_t cookie)
{
        struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
        struct virt_dma_desc *vd;
        unsigned long flags;

        spin_lock_irqsave(&cvc->pc->lock, flags);
        list_for_each_entry(vd, &cvc->pc->queue, node)
                if (vd->tx.cookie == cookie) {
                        spin_unlock_irqrestore(&cvc->pc->lock, flags);
                        return vd;
                }
        spin_unlock_irqrestore(&cvc->pc->lock, flags);

        list_for_each_entry(vd, &cvc->vc.desc_issued, node)
                if (vd->tx.cookie == cookie)
                        return vd;

        return NULL;
}

static enum dma_status mtk_cqdma_tx_status(struct dma_chan *c,
                                           dma_cookie_t cookie,
                                           struct dma_tx_state *txstate)
{
        struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
        struct mtk_cqdma_vdesc *cvd;
        struct virt_dma_desc *vd;
        enum dma_status ret;
        unsigned long flags;
        size_t bytes = 0;

        ret = dma_cookie_status(c, cookie, txstate);
        if (ret == DMA_COMPLETE || !txstate)
                return ret;

        spin_lock_irqsave(&cvc->vc.lock, flags);
        vd = mtk_cqdma_find_active_desc(c, cookie);
        spin_unlock_irqrestore(&cvc->vc.lock, flags);

        if (vd) {
                cvd = to_cqdma_vdesc(vd);
                bytes = cvd->residue;
        }

        dma_set_residue(txstate, bytes);

        return ret;
}

static void mtk_cqdma_issue_pending(struct dma_chan *c)
{
        struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
        unsigned long pc_flags;
        unsigned long vc_flags;

        /* acquire PC's lock before VS's lock for lock dependency in tasklet */
        spin_lock_irqsave(&cvc->pc->lock, pc_flags);
        spin_lock_irqsave(&cvc->vc.lock, vc_flags);

        if (vchan_issue_pending(&cvc->vc))
                mtk_cqdma_issue_vchan_pending(cvc);

        spin_unlock_irqrestore(&cvc->vc.lock, vc_flags);
        spin_unlock_irqrestore(&cvc->pc->lock, pc_flags);
}

static struct dma_async_tx_descriptor *
mtk_cqdma_prep_dma_memcpy(struct dma_chan *c, dma_addr_t dest,
                          dma_addr_t src, size_t len, unsigned long flags)
{
        struct mtk_cqdma_vdesc **cvd;
        struct dma_async_tx_descriptor *tx = NULL, *prev_tx = NULL;
        size_t i, tlen, nr_vd;

        /*
         * In the case that trsanction length is larger than the
         * DMA engine supports, a single memcpy transaction needs
         * to be separated into several DMA transactions.
         * Each DMA transaction would be described by a CVD,
         * and the first one is referred as the parent CVD,
         * while the others are child CVDs.
         * The parent CVD's tx descriptor is the only tx descriptor
         * returned to the DMA user, and it should not be completed
         * until all the child CVDs completed.
         */
        nr_vd = DIV_ROUND_UP(len, MTK_CQDMA_MAX_LEN);
        cvd = kcalloc(nr_vd, sizeof(*cvd), GFP_NOWAIT);
        if (!cvd)
                return NULL;

        for (i = 0; i < nr_vd; ++i) {
                cvd[i] = kzalloc(sizeof(*cvd[i]), GFP_NOWAIT);
                if (!cvd[i]) {
                        for (; i > 0; --i)
                                kfree(cvd[i - 1]);
                        return NULL;
                }

                /* setup dma channel */
                cvd[i]->ch = c;

                /* setup sourece, destination, and length */
                tlen = (len > MTK_CQDMA_MAX_LEN) ? MTK_CQDMA_MAX_LEN : len;
                cvd[i]->len = tlen;
                cvd[i]->src = src;
                cvd[i]->dest = dest;

                /* setup tx descriptor */
                tx = vchan_tx_prep(to_virt_chan(c), &cvd[i]->vd, flags);
                tx->next = NULL;

                if (!i) {
                        cvd[0]->residue = len;
                } else {
                        prev_tx->next = tx;
                        cvd[i]->residue = tlen;
                }

                cvd[i]->parent = cvd[0];

                /* update the src, dest, len, prev_tx for the next CVD */
                src += tlen;
                dest += tlen;
                len -= tlen;
                prev_tx = tx;
        }

        return &cvd[0]->vd.tx;
}

static void mtk_cqdma_free_inactive_desc(struct dma_chan *c)
{
        struct virt_dma_chan *vc = to_virt_chan(c);
        unsigned long flags;
        LIST_HEAD(head);

        /*
         * set desc_allocated, desc_submitted,
         * and desc_issued as the candicates to be freed
         */
        spin_lock_irqsave(&vc->lock, flags);
        list_splice_tail_init(&vc->desc_allocated, &head);
        list_splice_tail_init(&vc->desc_submitted, &head);
        list_splice_tail_init(&vc->desc_issued, &head);
        spin_unlock_irqrestore(&vc->lock, flags);

        /* free descriptor lists */
        vchan_dma_desc_free_list(vc, &head);
}

static void mtk_cqdma_free_active_desc(struct dma_chan *c)
{
        struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
        bool sync_needed = false;
        unsigned long pc_flags;
        unsigned long vc_flags;

        /* acquire PC's lock first due to lock dependency in dma ISR */
        spin_lock_irqsave(&cvc->pc->lock, pc_flags);
        spin_lock_irqsave(&cvc->vc.lock, vc_flags);

        /* synchronization is required if this VC is active */
        if (mtk_cqdma_is_vchan_active(cvc)) {
                cvc->issue_synchronize = true;
                sync_needed = true;
        }

        spin_unlock_irqrestore(&cvc->vc.lock, vc_flags);
        spin_unlock_irqrestore(&cvc->pc->lock, pc_flags);

        /* waiting for the completion of this VC */
        if (sync_needed)
                wait_for_completion(&cvc->issue_completion);

        /* free all descriptors in list desc_completed */
        vchan_synchronize(&cvc->vc);

        WARN_ONCE(!list_empty(&cvc->vc.desc_completed),
                  "Desc pending still in list desc_completed\n");
}

static int mtk_cqdma_terminate_all(struct dma_chan *c)
{
        /* free descriptors not processed yet by hardware */
        mtk_cqdma_free_inactive_desc(c);

        /* free descriptors being processed by hardware */
        mtk_cqdma_free_active_desc(c);

        return 0;
}

static int mtk_cqdma_alloc_chan_resources(struct dma_chan *c)
{
        struct mtk_cqdma_device *cqdma = to_cqdma_dev(c);
        struct mtk_cqdma_vchan *vc = to_cqdma_vchan(c);
        struct mtk_cqdma_pchan *pc = NULL;
        u32 i, min_refcnt = U32_MAX, refcnt;
        unsigned long flags;

        /* allocate PC with the minimun refcount */
        for (i = 0; i < cqdma->dma_channels; ++i) {
                refcnt = refcount_read(&cqdma->pc[i]->refcnt);
                if (refcnt < min_refcnt) {
                        pc = cqdma->pc[i];
                        min_refcnt = refcnt;
                }
        }

        if (!pc)
                return -ENOSPC;

        spin_lock_irqsave(&pc->lock, flags);

        if (!refcount_read(&pc->refcnt)) {
                /* allocate PC when the refcount is zero */
                mtk_cqdma_hard_reset(pc);

                /* enable interrupt for this PC */
                mtk_dma_set(pc, MTK_CQDMA_INT_EN, MTK_CQDMA_INT_EN_BIT);

                /*
                 * refcount_inc would complain increment on 0; use-after-free.
                 * Thus, we need to explicitly set it as 1 initially.
                 */
                refcount_set(&pc->refcnt, 1);
        } else {
                refcount_inc(&pc->refcnt);
        }

        spin_unlock_irqrestore(&pc->lock, flags);

        vc->pc = pc;

        return 0;
}

static void mtk_cqdma_free_chan_resources(struct dma_chan *c)
{
        struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
        unsigned long flags;

        /* free all descriptors in all lists on the VC */
        mtk_cqdma_terminate_all(c);

        spin_lock_irqsave(&cvc->pc->lock, flags);

        /* PC is not freed until there is no VC mapped to it */
        if (refcount_dec_and_test(&cvc->pc->refcnt)) {
                /* start the flush operation and stop the engine */
                mtk_dma_set(cvc->pc, MTK_CQDMA_FLUSH, MTK_CQDMA_FLUSH_BIT);

                /* wait for the completion of flush operation */
                if (mtk_cqdma_poll_engine_done(cvc->pc, true) < 0)
                        dev_err(cqdma2dev(to_cqdma_dev(c)), "cqdma flush timeout\n");

                /* clear the flush bit and interrupt flag */
                mtk_dma_clr(cvc->pc, MTK_CQDMA_FLUSH, MTK_CQDMA_FLUSH_BIT);
                mtk_dma_clr(cvc->pc, MTK_CQDMA_INT_FLAG,
                            MTK_CQDMA_INT_FLAG_BIT);

                /* disable interrupt for this PC */
                mtk_dma_clr(cvc->pc, MTK_CQDMA_INT_EN, MTK_CQDMA_INT_EN_BIT);
        }

        spin_unlock_irqrestore(&cvc->pc->lock, flags);
}

static int mtk_cqdma_hw_init(struct mtk_cqdma_device *cqdma)
{
        unsigned long flags;
        int err;
        u32 i;

        pm_runtime_enable(cqdma2dev(cqdma));
        pm_runtime_get_sync(cqdma2dev(cqdma));

        err = clk_prepare_enable(cqdma->clk);

        if (err) {
                pm_runtime_put_sync(cqdma2dev(cqdma));
                pm_runtime_disable(cqdma2dev(cqdma));
                return err;
        }

        /* reset all PCs */
        for (i = 0; i < cqdma->dma_channels; ++i) {
                spin_lock_irqsave(&cqdma->pc[i]->lock, flags);
                if (mtk_cqdma_hard_reset(cqdma->pc[i]) < 0) {
                        dev_err(cqdma2dev(cqdma), "cqdma hard reset timeout\n");
                        spin_unlock_irqrestore(&cqdma->pc[i]->lock, flags);

                        clk_disable_unprepare(cqdma->clk);
                        pm_runtime_put_sync(cqdma2dev(cqdma));
                        pm_runtime_disable(cqdma2dev(cqdma));
                        return -EINVAL;
                }
                spin_unlock_irqrestore(&cqdma->pc[i]->lock, flags);
        }

        return 0;
}

static void mtk_cqdma_hw_deinit(struct mtk_cqdma_device *cqdma)
{
        unsigned long flags;
        u32 i;

        /* reset all PCs */
        for (i = 0; i < cqdma->dma_channels; ++i) {
                spin_lock_irqsave(&cqdma->pc[i]->lock, flags);
                if (mtk_cqdma_hard_reset(cqdma->pc[i]) < 0)
                        dev_err(cqdma2dev(cqdma), "cqdma hard reset timeout\n");
                spin_unlock_irqrestore(&cqdma->pc[i]->lock, flags);
        }

        clk_disable_unprepare(cqdma->clk);

        pm_runtime_put_sync(cqdma2dev(cqdma));
        pm_runtime_disable(cqdma2dev(cqdma));
}

static const struct of_device_id mtk_cqdma_match[] = {
        { .compatible = "mediatek,mt6765-cqdma" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mtk_cqdma_match);

static int mtk_cqdma_probe(struct platform_device *pdev)
{
        struct mtk_cqdma_device *cqdma;
        struct mtk_cqdma_vchan *vc;
        struct dma_device *dd;
        struct resource *res;
        int err;
        u32 i;

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

        dd = &cqdma->ddev;

        cqdma->clk = devm_clk_get(&pdev->dev, "cqdma");
        if (IS_ERR(cqdma->clk)) {
                dev_err(&pdev->dev, "No clock for %s\n",
                        dev_name(&pdev->dev));
                return PTR_ERR(cqdma->clk);
        }

        dma_cap_set(DMA_MEMCPY, dd->cap_mask);

        dd->copy_align = MTK_CQDMA_ALIGN_SIZE;
        dd->device_alloc_chan_resources = mtk_cqdma_alloc_chan_resources;
        dd->device_free_chan_resources = mtk_cqdma_free_chan_resources;
        dd->device_tx_status = mtk_cqdma_tx_status;
        dd->device_issue_pending = mtk_cqdma_issue_pending;
        dd->device_prep_dma_memcpy = mtk_cqdma_prep_dma_memcpy;
        dd->device_terminate_all = mtk_cqdma_terminate_all;
        dd->src_addr_widths = MTK_CQDMA_DMA_BUSWIDTHS;
        dd->dst_addr_widths = MTK_CQDMA_DMA_BUSWIDTHS;
        dd->directions = BIT(DMA_MEM_TO_MEM);
        dd->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
        dd->dev = &pdev->dev;
        INIT_LIST_HEAD(&dd->channels);

        if (pdev->dev.of_node && of_property_read_u32(pdev->dev.of_node,
                                                      "dma-requests",
                                                      &cqdma->dma_requests)) {
                dev_info(&pdev->dev,
                         "Using %u as missing dma-requests property\n",
                         MTK_CQDMA_NR_VCHANS);

                cqdma->dma_requests = MTK_CQDMA_NR_VCHANS;
        }

        if (pdev->dev.of_node && of_property_read_u32(pdev->dev.of_node,
                                                      "dma-channels",
                                                      &cqdma->dma_channels)) {
                dev_info(&pdev->dev,
                         "Using %u as missing dma-channels property\n",
                         MTK_CQDMA_NR_PCHANS);

                cqdma->dma_channels = MTK_CQDMA_NR_PCHANS;
        }

        cqdma->pc = devm_kcalloc(&pdev->dev, cqdma->dma_channels,
                                 sizeof(*cqdma->pc), GFP_KERNEL);
        if (!cqdma->pc)
                return -ENOMEM;

        /* initialization for PCs */
        for (i = 0; i < cqdma->dma_channels; ++i) {
                cqdma->pc[i] = devm_kcalloc(&pdev->dev, 1,
                                            sizeof(**cqdma->pc), GFP_KERNEL);
                if (!cqdma->pc[i])
                        return -ENOMEM;

                INIT_LIST_HEAD(&cqdma->pc[i]->queue);
                spin_lock_init(&cqdma->pc[i]->lock);
                refcount_set(&cqdma->pc[i]->refcnt, 0);
                cqdma->pc[i]->base = devm_platform_ioremap_resource(pdev, i);
                if (IS_ERR(cqdma->pc[i]->base))
                        return PTR_ERR(cqdma->pc[i]->base);

                /* allocate IRQ resource */
                res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
                if (!res) {
                        dev_err(&pdev->dev, "No irq resource for %s\n",
                                dev_name(&pdev->dev));
                        return -EINVAL;
                }
                cqdma->pc[i]->irq = res->start;

                err = devm_request_irq(&pdev->dev, cqdma->pc[i]->irq,
                                       mtk_cqdma_irq, 0, dev_name(&pdev->dev),
                                       cqdma);
                if (err) {
                        dev_err(&pdev->dev,
                                "request_irq failed with err %d\n", err);
                        return -EINVAL;
                }
        }

        /* allocate resource for VCs */
        cqdma->vc = devm_kcalloc(&pdev->dev, cqdma->dma_requests,
                                 sizeof(*cqdma->vc), GFP_KERNEL);
        if (!cqdma->vc)
                return -ENOMEM;

        for (i = 0; i < cqdma->dma_requests; i++) {
                vc = &cqdma->vc[i];
                vc->vc.desc_free = mtk_cqdma_vdesc_free;
                vchan_init(&vc->vc, dd);
                init_completion(&vc->issue_completion);
        }

        err = dma_async_device_register(dd);
        if (err)
                return err;

        err = of_dma_controller_register(pdev->dev.of_node,
                                         of_dma_xlate_by_chan_id, cqdma);
        if (err) {
                dev_err(&pdev->dev,
                        "MediaTek CQDMA OF registration failed %d\n", err);
                goto err_unregister;
        }

        err = mtk_cqdma_hw_init(cqdma);
        if (err) {
                dev_err(&pdev->dev,
                        "MediaTek CQDMA HW initialization failed %d\n", err);
                goto err_unregister;
        }

        platform_set_drvdata(pdev, cqdma);

        /* initialize tasklet for each PC */
        for (i = 0; i < cqdma->dma_channels; ++i)
                tasklet_init(&cqdma->pc[i]->tasklet, mtk_cqdma_tasklet_cb,
                             (unsigned long)cqdma->pc[i]);

        dev_info(&pdev->dev, "MediaTek CQDMA driver registered\n");

        return 0;

err_unregister:
        dma_async_device_unregister(dd);

        return err;
}

static int mtk_cqdma_remove(struct platform_device *pdev)
{
        struct mtk_cqdma_device *cqdma = platform_get_drvdata(pdev);
        struct mtk_cqdma_vchan *vc;
        unsigned long flags;
        int i;

        /* kill VC task */
        for (i = 0; i < cqdma->dma_requests; i++) {
                vc = &cqdma->vc[i];

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

        /* disable interrupt */
        for (i = 0; i < cqdma->dma_channels; i++) {
                spin_lock_irqsave(&cqdma->pc[i]->lock, flags);
                mtk_dma_clr(cqdma->pc[i], MTK_CQDMA_INT_EN,
                            MTK_CQDMA_INT_EN_BIT);
                spin_unlock_irqrestore(&cqdma->pc[i]->lock, flags);

                /* Waits for any pending IRQ handlers to complete */
                synchronize_irq(cqdma->pc[i]->irq);

                tasklet_kill(&cqdma->pc[i]->tasklet);
        }

        /* disable hardware */
        mtk_cqdma_hw_deinit(cqdma);

        dma_async_device_unregister(&cqdma->ddev);
        of_dma_controller_free(pdev->dev.of_node);

        return 0;
}

static struct platform_driver mtk_cqdma_driver = {
        .probe = mtk_cqdma_probe,
        .remove = mtk_cqdma_remove,
        .driver = {
                .name           = KBUILD_MODNAME,
                .of_match_table = mtk_cqdma_match,
        },
};
module_platform_driver(mtk_cqdma_driver);

MODULE_DESCRIPTION("MediaTek CQDMA Controller Driver");
MODULE_AUTHOR("Shun-Chih Yu <shun-chih.yu@mediatek.com>");
MODULE_LICENSE("GPL v2");