// SPDX-License-Identifier: GPL-2.0
/*
 * Core driver for the Synopsys DesignWare DMA Controller
 *
 * Copyright (C) 2007-2008 Atmel Corporation
 * Copyright (C) 2010-2011 ST Microelectronics
 * Copyright (C) 2013 Intel Corporation
 */

#include <linux/bitops.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/io.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>

#include "../dmaengine.h"
#include "internal.h"

/*
 * This supports the Synopsys "DesignWare AHB Central DMA Controller",
 * (DW_ahb_dmac) which is used with various AMBA 2.0 systems (not all
 * of which use ARM any more).  See the "Databook" from Synopsys for
 * information beyond what licensees probably provide.
 *
 * The driver has been tested with the Atmel AT32AP7000, which does not
 * support descriptor writeback.
 */

/* The set of bus widths supported by the DMA controller */
#define DW_DMA_BUSWIDTHS                          \
        BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED)       | \
        BIT(DMA_SLAVE_BUSWIDTH_1_BYTE)          | \
        BIT(DMA_SLAVE_BUSWIDTH_2_BYTES)         | \
        BIT(DMA_SLAVE_BUSWIDTH_4_BYTES)

/*----------------------------------------------------------------------*/

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

static struct dw_desc *dwc_first_active(struct dw_dma_chan *dwc)
{
        return to_dw_desc(dwc->active_list.next);
}

static dma_cookie_t dwc_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct dw_desc          *desc = txd_to_dw_desc(tx);
        struct dw_dma_chan      *dwc = to_dw_dma_chan(tx->chan);
        dma_cookie_t            cookie;
        unsigned long           flags;

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

        /*
         * REVISIT: We should attempt to chain as many descriptors as
         * possible, perhaps even appending to those already submitted
         * for DMA. But this is hard to do in a race-free manner.
         */

        list_add_tail(&desc->desc_node, &dwc->queue);
        spin_unlock_irqrestore(&dwc->lock, flags);
        dev_vdbg(chan2dev(tx->chan), "%s: queued %u\n",
                 __func__, desc->txd.cookie);

        return cookie;
}

static struct dw_desc *dwc_desc_get(struct dw_dma_chan *dwc)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);
        struct dw_desc *desc;
        dma_addr_t phys;

        desc = dma_pool_zalloc(dw->desc_pool, GFP_ATOMIC, &phys);
        if (!desc)
                return NULL;

        dwc->descs_allocated++;
        INIT_LIST_HEAD(&desc->tx_list);
        dma_async_tx_descriptor_init(&desc->txd, &dwc->chan);
        desc->txd.tx_submit = dwc_tx_submit;
        desc->txd.flags = DMA_CTRL_ACK;
        desc->txd.phys = phys;
        return desc;
}

static void dwc_desc_put(struct dw_dma_chan *dwc, struct dw_desc *desc)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);
        struct dw_desc *child, *_next;

        if (unlikely(!desc))
                return;

        list_for_each_entry_safe(child, _next, &desc->tx_list, desc_node) {
                list_del(&child->desc_node);
                dma_pool_free(dw->desc_pool, child, child->txd.phys);
                dwc->descs_allocated--;
        }

        dma_pool_free(dw->desc_pool, desc, desc->txd.phys);
        dwc->descs_allocated--;
}

static void dwc_initialize(struct dw_dma_chan *dwc)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);

        dw->initialize_chan(dwc);

        /* Enable interrupts */
        channel_set_bit(dw, MASK.XFER, dwc->mask);
        channel_set_bit(dw, MASK.ERROR, dwc->mask);
}

/*----------------------------------------------------------------------*/

static inline void dwc_dump_chan_regs(struct dw_dma_chan *dwc)
{
        dev_err(chan2dev(&dwc->chan),
                "  SAR: 0x%x DAR: 0x%x LLP: 0x%x CTL: 0x%x:%08x\n",
                channel_readl(dwc, SAR),
                channel_readl(dwc, DAR),
                channel_readl(dwc, LLP),
                channel_readl(dwc, CTL_HI),
                channel_readl(dwc, CTL_LO));
}

static inline void dwc_chan_disable(struct dw_dma *dw, struct dw_dma_chan *dwc)
{
        channel_clear_bit(dw, CH_EN, dwc->mask);
        while (dma_readl(dw, CH_EN) & dwc->mask)
                cpu_relax();
}

/*----------------------------------------------------------------------*/

/* Perform single block transfer */
static inline void dwc_do_single_block(struct dw_dma_chan *dwc,
                                       struct dw_desc *desc)
{
        struct dw_dma   *dw = to_dw_dma(dwc->chan.device);
        u32             ctllo;

        /*
         * Software emulation of LLP mode relies on interrupts to continue
         * multi block transfer.
         */
        ctllo = lli_read(desc, ctllo) | DWC_CTLL_INT_EN;

        channel_writel(dwc, SAR, lli_read(desc, sar));
        channel_writel(dwc, DAR, lli_read(desc, dar));
        channel_writel(dwc, CTL_LO, ctllo);
        channel_writel(dwc, CTL_HI, lli_read(desc, ctlhi));
        channel_set_bit(dw, CH_EN, dwc->mask);

        /* Move pointer to next descriptor */
        dwc->tx_node_active = dwc->tx_node_active->next;
}

/* Called with dwc->lock held and bh disabled */
static void dwc_dostart(struct dw_dma_chan *dwc, struct dw_desc *first)
{
        struct dw_dma   *dw = to_dw_dma(dwc->chan.device);
        u8              lms = DWC_LLP_LMS(dwc->dws.m_master);
        unsigned long   was_soft_llp;

        /* ASSERT:  channel is idle */
        if (dma_readl(dw, CH_EN) & dwc->mask) {
                dev_err(chan2dev(&dwc->chan),
                        "%s: BUG: Attempted to start non-idle channel\n",
                        __func__);
                dwc_dump_chan_regs(dwc);

                /* The tasklet will hopefully advance the queue... */
                return;
        }

        if (dwc->nollp) {
                was_soft_llp = test_and_set_bit(DW_DMA_IS_SOFT_LLP,
                                                &dwc->flags);
                if (was_soft_llp) {
                        dev_err(chan2dev(&dwc->chan),
                                "BUG: Attempted to start new LLP transfer inside ongoing one\n");
                        return;
                }

                dwc_initialize(dwc);

                first->residue = first->total_len;
                dwc->tx_node_active = &first->tx_list;

                /* Submit first block */
                dwc_do_single_block(dwc, first);

                return;
        }

        dwc_initialize(dwc);

        channel_writel(dwc, LLP, first->txd.phys | lms);
        channel_writel(dwc, CTL_LO, DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN);
        channel_writel(dwc, CTL_HI, 0);
        channel_set_bit(dw, CH_EN, dwc->mask);
}

static void dwc_dostart_first_queued(struct dw_dma_chan *dwc)
{
        struct dw_desc *desc;

        if (list_empty(&dwc->queue))
                return;

        list_move(dwc->queue.next, &dwc->active_list);
        desc = dwc_first_active(dwc);
        dev_vdbg(chan2dev(&dwc->chan), "%s: started %u\n", __func__, desc->txd.cookie);
        dwc_dostart(dwc, desc);
}

/*----------------------------------------------------------------------*/

static void
dwc_descriptor_complete(struct dw_dma_chan *dwc, struct dw_desc *desc,
                bool callback_required)
{
        struct dma_async_tx_descriptor  *txd = &desc->txd;
        struct dw_desc                  *child;
        unsigned long                   flags;
        struct dmaengine_desc_callback  cb;

        dev_vdbg(chan2dev(&dwc->chan), "descriptor %u complete\n", txd->cookie);

        spin_lock_irqsave(&dwc->lock, flags);
        dma_cookie_complete(txd);
        if (callback_required)
                dmaengine_desc_get_callback(txd, &cb);
        else
                memset(&cb, 0, sizeof(cb));

        /* async_tx_ack */
        list_for_each_entry(child, &desc->tx_list, desc_node)
                async_tx_ack(&child->txd);
        async_tx_ack(&desc->txd);
        dwc_desc_put(dwc, desc);
        spin_unlock_irqrestore(&dwc->lock, flags);

        dmaengine_desc_callback_invoke(&cb, NULL);
}

static void dwc_complete_all(struct dw_dma *dw, struct dw_dma_chan *dwc)
{
        struct dw_desc *desc, *_desc;
        LIST_HEAD(list);
        unsigned long flags;

        spin_lock_irqsave(&dwc->lock, flags);
        if (dma_readl(dw, CH_EN) & dwc->mask) {
                dev_err(chan2dev(&dwc->chan),
                        "BUG: XFER bit set, but channel not idle!\n");

                /* Try to continue after resetting the channel... */
                dwc_chan_disable(dw, dwc);
        }

        /*
         * Submit queued descriptors ASAP, i.e. before we go through
         * the completed ones.
         */
        list_splice_init(&dwc->active_list, &list);
        dwc_dostart_first_queued(dwc);

        spin_unlock_irqrestore(&dwc->lock, flags);

        list_for_each_entry_safe(desc, _desc, &list, desc_node)
                dwc_descriptor_complete(dwc, desc, true);
}

/* Returns how many bytes were already received from source */
static inline u32 dwc_get_sent(struct dw_dma_chan *dwc)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);
        u32 ctlhi = channel_readl(dwc, CTL_HI);
        u32 ctllo = channel_readl(dwc, CTL_LO);

        return dw->block2bytes(dwc, ctlhi, ctllo >> 4 & 7);
}

static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)
{
        dma_addr_t llp;
        struct dw_desc *desc, *_desc;
        struct dw_desc *child;
        u32 status_xfer;
        unsigned long flags;

        spin_lock_irqsave(&dwc->lock, flags);
        llp = channel_readl(dwc, LLP);
        status_xfer = dma_readl(dw, RAW.XFER);

        if (status_xfer & dwc->mask) {
                /* Everything we've submitted is done */
                dma_writel(dw, CLEAR.XFER, dwc->mask);

                if (test_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags)) {
                        struct list_head *head, *active = dwc->tx_node_active;

                        /*
                         * We are inside first active descriptor.
                         * Otherwise something is really wrong.
                         */
                        desc = dwc_first_active(dwc);

                        head = &desc->tx_list;
                        if (active != head) {
                                /* Update residue to reflect last sent descriptor */
                                if (active == head->next)
                                        desc->residue -= desc->len;
                                else
                                        desc->residue -= to_dw_desc(active->prev)->len;

                                child = to_dw_desc(active);

                                /* Submit next block */
                                dwc_do_single_block(dwc, child);

                                spin_unlock_irqrestore(&dwc->lock, flags);
                                return;
                        }

                        /* We are done here */
                        clear_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags);
                }

                spin_unlock_irqrestore(&dwc->lock, flags);

                dwc_complete_all(dw, dwc);
                return;
        }

        if (list_empty(&dwc->active_list)) {
                spin_unlock_irqrestore(&dwc->lock, flags);
                return;
        }

        if (test_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags)) {
                dev_vdbg(chan2dev(&dwc->chan), "%s: soft LLP mode\n", __func__);
                spin_unlock_irqrestore(&dwc->lock, flags);
                return;
        }

        dev_vdbg(chan2dev(&dwc->chan), "%s: llp=%pad\n", __func__, &llp);

        list_for_each_entry_safe(desc, _desc, &dwc->active_list, desc_node) {
                /* Initial residue value */
                desc->residue = desc->total_len;

                /* Check first descriptors addr */
                if (desc->txd.phys == DWC_LLP_LOC(llp)) {
                        spin_unlock_irqrestore(&dwc->lock, flags);
                        return;
                }

                /* Check first descriptors llp */
                if (lli_read(desc, llp) == llp) {
                        /* This one is currently in progress */
                        desc->residue -= dwc_get_sent(dwc);
                        spin_unlock_irqrestore(&dwc->lock, flags);
                        return;
                }

                desc->residue -= desc->len;
                list_for_each_entry(child, &desc->tx_list, desc_node) {
                        if (lli_read(child, llp) == llp) {
                                /* Currently in progress */
                                desc->residue -= dwc_get_sent(dwc);
                                spin_unlock_irqrestore(&dwc->lock, flags);
                                return;
                        }
                        desc->residue -= child->len;
                }

                /*
                 * No descriptors so far seem to be in progress, i.e.
                 * this one must be done.
                 */
                spin_unlock_irqrestore(&dwc->lock, flags);
                dwc_descriptor_complete(dwc, desc, true);
                spin_lock_irqsave(&dwc->lock, flags);
        }

        dev_err(chan2dev(&dwc->chan),
                "BUG: All descriptors done, but channel not idle!\n");

        /* Try to continue after resetting the channel... */
        dwc_chan_disable(dw, dwc);

        dwc_dostart_first_queued(dwc);
        spin_unlock_irqrestore(&dwc->lock, flags);
}

static inline void dwc_dump_lli(struct dw_dma_chan *dwc, struct dw_desc *desc)
{
        dev_crit(chan2dev(&dwc->chan), "  desc: s0x%x d0x%x l0x%x c0x%x:%x\n",
                 lli_read(desc, sar),
                 lli_read(desc, dar),
                 lli_read(desc, llp),
                 lli_read(desc, ctlhi),
                 lli_read(desc, ctllo));
}

static void dwc_handle_error(struct dw_dma *dw, struct dw_dma_chan *dwc)
{
        struct dw_desc *bad_desc;
        struct dw_desc *child;
        unsigned long flags;

        dwc_scan_descriptors(dw, dwc);

        spin_lock_irqsave(&dwc->lock, flags);

        /*
         * The descriptor currently at the head of the active list is
         * borked. Since we don't have any way to report errors, we'll
         * just have to scream loudly and try to carry on.
         */
        bad_desc = dwc_first_active(dwc);
        list_del_init(&bad_desc->desc_node);
        list_move(dwc->queue.next, dwc->active_list.prev);

        /* Clear the error flag and try to restart the controller */
        dma_writel(dw, CLEAR.ERROR, dwc->mask);
        if (!list_empty(&dwc->active_list))
                dwc_dostart(dwc, dwc_first_active(dwc));

        /*
         * WARN may seem harsh, but since this only happens
         * when someone submits a bad physical address in a
         * descriptor, we should consider ourselves lucky that the
         * controller flagged an error instead of scribbling over
         * random memory locations.
         */
        dev_WARN(chan2dev(&dwc->chan), "Bad descriptor submitted for DMA!\n"
                                       "  cookie: %d\n", bad_desc->txd.cookie);
        dwc_dump_lli(dwc, bad_desc);
        list_for_each_entry(child, &bad_desc->tx_list, desc_node)
                dwc_dump_lli(dwc, child);

        spin_unlock_irqrestore(&dwc->lock, flags);

        /* Pretend the descriptor completed successfully */
        dwc_descriptor_complete(dwc, bad_desc, true);
}

static void dw_dma_tasklet(struct tasklet_struct *t)
{
        struct dw_dma *dw = from_tasklet(dw, t, tasklet);
        struct dw_dma_chan *dwc;
        u32 status_xfer;
        u32 status_err;
        unsigned int i;

        status_xfer = dma_readl(dw, RAW.XFER);
        status_err = dma_readl(dw, RAW.ERROR);

        dev_vdbg(dw->dma.dev, "%s: status_err=%x\n", __func__, status_err);

        for (i = 0; i < dw->dma.chancnt; i++) {
                dwc = &dw->chan[i];
                if (test_bit(DW_DMA_IS_CYCLIC, &dwc->flags))
                        dev_vdbg(dw->dma.dev, "Cyclic xfer is not implemented\n");
                else if (status_err & (1 << i))
                        dwc_handle_error(dw, dwc);
                else if (status_xfer & (1 << i))
                        dwc_scan_descriptors(dw, dwc);
        }

        /* Re-enable interrupts */
        channel_set_bit(dw, MASK.XFER, dw->all_chan_mask);
        channel_set_bit(dw, MASK.ERROR, dw->all_chan_mask);
}

static irqreturn_t dw_dma_interrupt(int irq, void *dev_id)
{
        struct dw_dma *dw = dev_id;
        u32 status;

        /* Check if we have any interrupt from the DMAC which is not in use */
        if (!dw->in_use)
                return IRQ_NONE;

        status = dma_readl(dw, STATUS_INT);
        dev_vdbg(dw->dma.dev, "%s: status=0x%x\n", __func__, status);

        /* Check if we have any interrupt from the DMAC */
        if (!status)
                return IRQ_NONE;

        /*
         * Just disable the interrupts. We'll turn them back on in the
         * softirq handler.
         */
        channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);

        status = dma_readl(dw, STATUS_INT);
        if (status) {
                dev_err(dw->dma.dev,
                        "BUG: Unexpected interrupts pending: 0x%x\n",
                        status);

                /* Try to recover */
                channel_clear_bit(dw, MASK.XFER, (1 << 8) - 1);
                channel_clear_bit(dw, MASK.BLOCK, (1 << 8) - 1);
                channel_clear_bit(dw, MASK.SRC_TRAN, (1 << 8) - 1);
                channel_clear_bit(dw, MASK.DST_TRAN, (1 << 8) - 1);
                channel_clear_bit(dw, MASK.ERROR, (1 << 8) - 1);
        }

        tasklet_schedule(&dw->tasklet);

        return IRQ_HANDLED;
}

/*----------------------------------------------------------------------*/

static struct dma_async_tx_descriptor *
dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                size_t len, unsigned long flags)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        struct dw_dma           *dw = to_dw_dma(chan->device);
        struct dw_desc          *desc;
        struct dw_desc          *first;
        struct dw_desc          *prev;
        size_t                  xfer_count;
        size_t                  offset;
        u8                      m_master = dwc->dws.m_master;
        unsigned int            src_width;
        unsigned int            dst_width;
        unsigned int            data_width = dw->pdata->data_width[m_master];
        u32                     ctllo, ctlhi;
        u8                      lms = DWC_LLP_LMS(m_master);

        dev_vdbg(chan2dev(chan),
                        "%s: d%pad s%pad l0x%zx f0x%lx\n", __func__,
                        &dest, &src, len, flags);

        if (unlikely(!len)) {
                dev_dbg(chan2dev(chan), "%s: length is zero!\n", __func__);
                return NULL;
        }

        dwc->direction = DMA_MEM_TO_MEM;

        src_width = dst_width = __ffs(data_width | src | dest | len);

        ctllo = dw->prepare_ctllo(dwc)
                        | DWC_CTLL_DST_WIDTH(dst_width)
                        | DWC_CTLL_SRC_WIDTH(src_width)
                        | DWC_CTLL_DST_INC
                        | DWC_CTLL_SRC_INC
                        | DWC_CTLL_FC_M2M;
        prev = first = NULL;

        for (offset = 0; offset < len; offset += xfer_count) {
                desc = dwc_desc_get(dwc);
                if (!desc)
                        goto err_desc_get;

                ctlhi = dw->bytes2block(dwc, len - offset, src_width, &xfer_count);

                lli_write(desc, sar, src + offset);
                lli_write(desc, dar, dest + offset);
                lli_write(desc, ctllo, ctllo);
                lli_write(desc, ctlhi, ctlhi);
                desc->len = xfer_count;

                if (!first) {
                        first = desc;
                } else {
                        lli_write(prev, llp, desc->txd.phys | lms);
                        list_add_tail(&desc->desc_node, &first->tx_list);
                }
                prev = desc;
        }

        if (flags & DMA_PREP_INTERRUPT)
                /* Trigger interrupt after last block */
                lli_set(prev, ctllo, DWC_CTLL_INT_EN);

        prev->lli.llp = 0;
        lli_clear(prev, ctllo, DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN);
        first->txd.flags = flags;
        first->total_len = len;

        return &first->txd;

err_desc_get:
        dwc_desc_put(dwc, first);
        return NULL;
}

static struct dma_async_tx_descriptor *
dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                unsigned int sg_len, enum dma_transfer_direction direction,
                unsigned long flags, void *context)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        struct dw_dma           *dw = to_dw_dma(chan->device);
        struct dma_slave_config *sconfig = &dwc->dma_sconfig;
        struct dw_desc          *prev;
        struct dw_desc          *first;
        u32                     ctllo, ctlhi;
        u8                      m_master = dwc->dws.m_master;
        u8                      lms = DWC_LLP_LMS(m_master);
        dma_addr_t              reg;
        unsigned int            reg_width;
        unsigned int            mem_width;
        unsigned int            data_width = dw->pdata->data_width[m_master];
        unsigned int            i;
        struct scatterlist      *sg;
        size_t                  total_len = 0;

        dev_vdbg(chan2dev(chan), "%s\n", __func__);

        if (unlikely(!is_slave_direction(direction) || !sg_len))
                return NULL;

        dwc->direction = direction;

        prev = first = NULL;

        switch (direction) {
        case DMA_MEM_TO_DEV:
                reg_width = __ffs(sconfig->dst_addr_width);
                reg = sconfig->dst_addr;
                ctllo = dw->prepare_ctllo(dwc)
                                | DWC_CTLL_DST_WIDTH(reg_width)
                                | DWC_CTLL_DST_FIX
                                | DWC_CTLL_SRC_INC;

                ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_M2P) :
                        DWC_CTLL_FC(DW_DMA_FC_D_M2P);

                for_each_sg(sgl, sg, sg_len, i) {
                        struct dw_desc  *desc;
                        u32             len, mem;
                        size_t          dlen;

                        mem = sg_dma_address(sg);
                        len = sg_dma_len(sg);

                        mem_width = __ffs(data_width | mem | len);

slave_sg_todev_fill_desc:
                        desc = dwc_desc_get(dwc);
                        if (!desc)
                                goto err_desc_get;

                        ctlhi = dw->bytes2block(dwc, len, mem_width, &dlen);

                        lli_write(desc, sar, mem);
                        lli_write(desc, dar, reg);
                        lli_write(desc, ctlhi, ctlhi);
                        lli_write(desc, ctllo, ctllo | DWC_CTLL_SRC_WIDTH(mem_width));
                        desc->len = dlen;

                        if (!first) {
                                first = desc;
                        } else {
                                lli_write(prev, llp, desc->txd.phys | lms);
                                list_add_tail(&desc->desc_node, &first->tx_list);
                        }
                        prev = desc;

                        mem += dlen;
                        len -= dlen;
                        total_len += dlen;

                        if (len)
                                goto slave_sg_todev_fill_desc;
                }
                break;
        case DMA_DEV_TO_MEM:
                reg_width = __ffs(sconfig->src_addr_width);
                reg = sconfig->src_addr;
                ctllo = dw->prepare_ctllo(dwc)
                                | DWC_CTLL_SRC_WIDTH(reg_width)
                                | DWC_CTLL_DST_INC
                                | DWC_CTLL_SRC_FIX;

                ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_P2M) :
                        DWC_CTLL_FC(DW_DMA_FC_D_P2M);

                for_each_sg(sgl, sg, sg_len, i) {
                        struct dw_desc  *desc;
                        u32             len, mem;
                        size_t          dlen;

                        mem = sg_dma_address(sg);
                        len = sg_dma_len(sg);

slave_sg_fromdev_fill_desc:
                        desc = dwc_desc_get(dwc);
                        if (!desc)
                                goto err_desc_get;

                        ctlhi = dw->bytes2block(dwc, len, reg_width, &dlen);

                        lli_write(desc, sar, reg);
                        lli_write(desc, dar, mem);
                        lli_write(desc, ctlhi, ctlhi);
                        mem_width = __ffs(data_width | mem);
                        lli_write(desc, ctllo, ctllo | DWC_CTLL_DST_WIDTH(mem_width));
                        desc->len = dlen;

                        if (!first) {
                                first = desc;
                        } else {
                                lli_write(prev, llp, desc->txd.phys | lms);
                                list_add_tail(&desc->desc_node, &first->tx_list);
                        }
                        prev = desc;

                        mem += dlen;
                        len -= dlen;
                        total_len += dlen;

                        if (len)
                                goto slave_sg_fromdev_fill_desc;
                }
                break;
        default:
                return NULL;
        }

        if (flags & DMA_PREP_INTERRUPT)
                /* Trigger interrupt after last block */
                lli_set(prev, ctllo, DWC_CTLL_INT_EN);

        prev->lli.llp = 0;
        lli_clear(prev, ctllo, DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN);
        first->total_len = total_len;

        return &first->txd;

err_desc_get:
        dev_err(chan2dev(chan),
                "not enough descriptors available. Direction %d\n", direction);
        dwc_desc_put(dwc, first);
        return NULL;
}

bool dw_dma_filter(struct dma_chan *chan, void *param)
{
        struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
        struct dw_dma_slave *dws = param;

        if (dws->dma_dev != chan->device->dev)
                return false;

        /* permit channels in accordance with the channels mask */
        if (dws->channels && !(dws->channels & dwc->mask))
                return false;

        /* We have to copy data since dws can be temporary storage */
        memcpy(&dwc->dws, dws, sizeof(struct dw_dma_slave));

        return true;
}
EXPORT_SYMBOL_GPL(dw_dma_filter);

static int dwc_config(struct dma_chan *chan, struct dma_slave_config *sconfig)
{
        struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
        struct dw_dma *dw = to_dw_dma(chan->device);

        memcpy(&dwc->dma_sconfig, sconfig, sizeof(*sconfig));

        dwc->dma_sconfig.src_maxburst =
                clamp(dwc->dma_sconfig.src_maxburst, 0U, dwc->max_burst);
        dwc->dma_sconfig.dst_maxburst =
                clamp(dwc->dma_sconfig.dst_maxburst, 0U, dwc->max_burst);

        dw->encode_maxburst(dwc, &dwc->dma_sconfig.src_maxburst);
        dw->encode_maxburst(dwc, &dwc->dma_sconfig.dst_maxburst);

        return 0;
}

static void dwc_chan_pause(struct dw_dma_chan *dwc, bool drain)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);
        unsigned int            count = 20;     /* timeout iterations */

        dw->suspend_chan(dwc, drain);

        while (!(channel_readl(dwc, CFG_LO) & DWC_CFGL_FIFO_EMPTY) && count--)
                udelay(2);

        set_bit(DW_DMA_IS_PAUSED, &dwc->flags);
}

static int dwc_pause(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);
        dwc_chan_pause(dwc, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;
}

static inline void dwc_chan_resume(struct dw_dma_chan *dwc, bool drain)
{
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);

        dw->resume_chan(dwc, drain);

        clear_bit(DW_DMA_IS_PAUSED, &dwc->flags);
}

static int dwc_resume(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);

        if (test_bit(DW_DMA_IS_PAUSED, &dwc->flags))
                dwc_chan_resume(dwc, false);

        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;
}

static int dwc_terminate_all(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        struct dw_dma           *dw = to_dw_dma(chan->device);
        struct dw_desc          *desc, *_desc;
        unsigned long           flags;
        LIST_HEAD(list);

        spin_lock_irqsave(&dwc->lock, flags);

        clear_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags);

        dwc_chan_pause(dwc, true);

        dwc_chan_disable(dw, dwc);

        dwc_chan_resume(dwc, true);

        /* active_list entries will end up before queued entries */
        list_splice_init(&dwc->queue, &list);
        list_splice_init(&dwc->active_list, &list);

        spin_unlock_irqrestore(&dwc->lock, flags);

        /* Flush all pending and queued descriptors */
        list_for_each_entry_safe(desc, _desc, &list, desc_node)
                dwc_descriptor_complete(dwc, desc, false);

        return 0;
}

static struct dw_desc *dwc_find_desc(struct dw_dma_chan *dwc, dma_cookie_t c)
{
        struct dw_desc *desc;

        list_for_each_entry(desc, &dwc->active_list, desc_node)
                if (desc->txd.cookie == c)
                        return desc;

        return NULL;
}

static u32 dwc_get_residue(struct dw_dma_chan *dwc, dma_cookie_t cookie)
{
        struct dw_desc *desc;
        unsigned long flags;
        u32 residue;

        spin_lock_irqsave(&dwc->lock, flags);

        desc = dwc_find_desc(dwc, cookie);
        if (desc) {
                if (desc == dwc_first_active(dwc)) {
                        residue = desc->residue;
                        if (test_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags) && residue)
                                residue -= dwc_get_sent(dwc);
                } else {
                        residue = desc->total_len;
                }
        } else {
                residue = 0;
        }

        spin_unlock_irqrestore(&dwc->lock, flags);
        return residue;
}

static enum dma_status
dwc_tx_status(struct dma_chan *chan,
              dma_cookie_t cookie,
              struct dma_tx_state *txstate)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        enum dma_status         ret;

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

        dwc_scan_descriptors(to_dw_dma(chan->device), dwc);

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

        dma_set_residue(txstate, dwc_get_residue(dwc, cookie));

        if (test_bit(DW_DMA_IS_PAUSED, &dwc->flags) && ret == DMA_IN_PROGRESS)
                return DMA_PAUSED;

        return ret;
}

static void dwc_issue_pending(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);
        if (list_empty(&dwc->active_list))
                dwc_dostart_first_queued(dwc);
        spin_unlock_irqrestore(&dwc->lock, flags);
}

/*----------------------------------------------------------------------*/

void do_dw_dma_off(struct dw_dma *dw)
{
        dma_writel(dw, CFG, 0);

        channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask);
        channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);

        while (dma_readl(dw, CFG) & DW_CFG_DMA_EN)
                cpu_relax();
}

void do_dw_dma_on(struct dw_dma *dw)
{
        dma_writel(dw, CFG, DW_CFG_DMA_EN);
}

static int dwc_alloc_chan_resources(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        struct dw_dma           *dw = to_dw_dma(chan->device);

        dev_vdbg(chan2dev(chan), "%s\n", __func__);

        /* ASSERT:  channel is idle */
        if (dma_readl(dw, CH_EN) & dwc->mask) {
                dev_dbg(chan2dev(chan), "DMA channel not idle?\n");
                return -EIO;
        }

        dma_cookie_init(chan);

        /*
         * NOTE: some controllers may have additional features that we
         * need to initialize here, like "scatter-gather" (which
         * doesn't mean what you think it means), and status writeback.
         */

        /*
         * We need controller-specific data to set up slave transfers.

         */
        if (chan->private && !dw_dma_filter(chan, chan->private)) {
                dev_warn(chan2dev(chan), "Wrong controller-specific data\n");
                return -EINVAL;
        }

        /* Enable controller here if needed */
        if (!dw->in_use)
                do_dw_dma_on(dw);
        dw->in_use |= dwc->mask;

        return 0;
}

static void dwc_free_chan_resources(struct dma_chan *chan)
{
        struct dw_dma_chan      *dwc = to_dw_dma_chan(chan);
        struct dw_dma           *dw = to_dw_dma(chan->device);
        unsigned long           flags;

        dev_dbg(chan2dev(chan), "%s: descs allocated=%u\n", __func__,
                        dwc->descs_allocated);

        /* ASSERT:  channel is idle */
        BUG_ON(!list_empty(&dwc->active_list));
        BUG_ON(!list_empty(&dwc->queue));
        BUG_ON(dma_readl(to_dw_dma(chan->device), CH_EN) & dwc->mask);

        spin_lock_irqsave(&dwc->lock, flags);

        /* Clear custom channel configuration */
        memset(&dwc->dws, 0, sizeof(struct dw_dma_slave));

        /* Disable interrupts */
        channel_clear_bit(dw, MASK.XFER, dwc->mask);
        channel_clear_bit(dw, MASK.BLOCK, dwc->mask);
        channel_clear_bit(dw, MASK.ERROR, dwc->mask);

        spin_unlock_irqrestore(&dwc->lock, flags);

        /* Disable controller in case it was a last user */
        dw->in_use &= ~dwc->mask;
        if (!dw->in_use)
                do_dw_dma_off(dw);

        dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
}

static void dwc_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
{
        struct dw_dma_chan *dwc = to_dw_dma_chan(chan);

        caps->max_burst = dwc->max_burst;

        /*
         * It might be crucial for some devices to have the hardware
         * accelerated multi-block transfers supported, aka LLPs in DW DMAC
         * notation. So if LLPs are supported then max_sg_burst is set to
         * zero which means unlimited number of SG entries can be handled in a
         * single DMA transaction, otherwise it's just one SG entry.
         */
        if (dwc->nollp)
                caps->max_sg_burst = 1;
        else
                caps->max_sg_burst = 0;
}

int do_dma_probe(struct dw_dma_chip *chip)
{
        struct dw_dma *dw = chip->dw;
        struct dw_dma_platform_data *pdata;
        bool                    autocfg = false;
        unsigned int            dw_params;
        unsigned int            i;
        int                     err;

        dw->pdata = devm_kzalloc(chip->dev, sizeof(*dw->pdata), GFP_KERNEL);
        if (!dw->pdata)
                return -ENOMEM;

        dw->regs = chip->regs;

        pm_runtime_get_sync(chip->dev);

        if (!chip->pdata) {
                dw_params = dma_readl(dw, DW_PARAMS);
                dev_dbg(chip->dev, "DW_PARAMS: 0x%08x\n", dw_params);

                autocfg = dw_params >> DW_PARAMS_EN & 1;
                if (!autocfg) {
                        err = -EINVAL;
                        goto err_pdata;
                }

                /* Reassign the platform data pointer */
                pdata = dw->pdata;

                /* Get hardware configuration parameters */
                pdata->nr_channels = (dw_params >> DW_PARAMS_NR_CHAN & 7) + 1;
                pdata->nr_masters = (dw_params >> DW_PARAMS_NR_MASTER & 3) + 1;
                for (i = 0; i < pdata->nr_masters; i++) {
                        pdata->data_width[i] =
                                4 << (dw_params >> DW_PARAMS_DATA_WIDTH(i) & 3);
                }
                pdata->block_size = dma_readl(dw, MAX_BLK_SIZE);

                /* Fill platform data with the default values */
                pdata->chan_allocation_order = CHAN_ALLOCATION_ASCENDING;
                pdata->chan_priority = CHAN_PRIORITY_ASCENDING;
        } else if (chip->pdata->nr_channels > DW_DMA_MAX_NR_CHANNELS) {
                err = -EINVAL;
                goto err_pdata;
        } else {
                memcpy(dw->pdata, chip->pdata, sizeof(*dw->pdata));

                /* Reassign the platform data pointer */
                pdata = dw->pdata;
        }

        dw->chan = devm_kcalloc(chip->dev, pdata->nr_channels, sizeof(*dw->chan),
                                GFP_KERNEL);
        if (!dw->chan) {
                err = -ENOMEM;
                goto err_pdata;
        }

        /* Calculate all channel mask before DMA setup */
        dw->all_chan_mask = (1 << pdata->nr_channels) - 1;

        /* Force dma off, just in case */
        dw->disable(dw);

        /* Device and instance ID for IRQ and DMA pool */
        dw->set_device_name(dw, chip->id);

        /* Create a pool of consistent memory blocks for hardware descriptors */
        dw->desc_pool = dmam_pool_create(dw->name, chip->dev,
                                         sizeof(struct dw_desc), 4, 0);
        if (!dw->desc_pool) {
                dev_err(chip->dev, "No memory for descriptors dma pool\n");
                err = -ENOMEM;
                goto err_pdata;
        }

        tasklet_setup(&dw->tasklet, dw_dma_tasklet);

        err = request_irq(chip->irq, dw_dma_interrupt, IRQF_SHARED,
                          dw->name, dw);
        if (err)
                goto err_pdata;

        INIT_LIST_HEAD(&dw->dma.channels);
        for (i = 0; i < pdata->nr_channels; i++) {
                struct dw_dma_chan      *dwc = &dw->chan[i];

                dwc->chan.device = &dw->dma;
                dma_cookie_init(&dwc->chan);
                if (pdata->chan_allocation_order == CHAN_ALLOCATION_ASCENDING)
                        list_add_tail(&dwc->chan.device_node,
                                        &dw->dma.channels);
                else
                        list_add(&dwc->chan.device_node, &dw->dma.channels);

                /* 7 is highest priority & 0 is lowest. */
                if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING)
                        dwc->priority = pdata->nr_channels - i - 1;
                else
                        dwc->priority = i;

                dwc->ch_regs = &__dw_regs(dw)->CHAN[i];
                spin_lock_init(&dwc->lock);
                dwc->mask = 1 << i;

                INIT_LIST_HEAD(&dwc->active_list);
                INIT_LIST_HEAD(&dwc->queue);

                channel_clear_bit(dw, CH_EN, dwc->mask);

                dwc->direction = DMA_TRANS_NONE;

                /* Hardware configuration */
                if (autocfg) {
                        unsigned int r = DW_DMA_MAX_NR_CHANNELS - i - 1;
                        void __iomem *addr = &__dw_regs(dw)->DWC_PARAMS[r];
                        unsigned int dwc_params = readl(addr);

                        dev_dbg(chip->dev, "DWC_PARAMS[%d]: 0x%08x\n", i,
                                           dwc_params);

                        /*
                         * Decode maximum block size for given channel. The
                         * stored 4 bit value represents blocks from 0x00 for 3
                         * up to 0x0a for 4095.
                         */
                        dwc->block_size =
                                (4 << ((pdata->block_size >> 4 * i) & 0xf)) - 1;

                        /*
                         * According to the DW DMA databook the true scatter-
                         * gether LLPs aren't available if either multi-block
                         * config is disabled (CHx_MULTI_BLK_EN == 0) or the
                         * LLP register is hard-coded to zeros
                         * (CHx_HC_LLP == 1).
                         */
                        dwc->nollp =
                                (dwc_params >> DWC_PARAMS_MBLK_EN & 0x1) == 0 ||
                                (dwc_params >> DWC_PARAMS_HC_LLP & 0x1) == 1;
                        dwc->max_burst =
                                (0x4 << (dwc_params >> DWC_PARAMS_MSIZE & 0x7));
                } else {
                        dwc->block_size = pdata->block_size;
                        dwc->nollp = !pdata->multi_block[i];
                        dwc->max_burst = pdata->max_burst[i] ?: DW_DMA_MAX_BURST;
                }
        }

        /* Clear all interrupts on all channels. */
        dma_writel(dw, CLEAR.XFER, dw->all_chan_mask);
        dma_writel(dw, CLEAR.BLOCK, dw->all_chan_mask);
        dma_writel(dw, CLEAR.SRC_TRAN, dw->all_chan_mask);
        dma_writel(dw, CLEAR.DST_TRAN, dw->all_chan_mask);
        dma_writel(dw, CLEAR.ERROR, dw->all_chan_mask);

        /* Set capabilities */
        dma_cap_set(DMA_SLAVE, dw->dma.cap_mask);
        dma_cap_set(DMA_PRIVATE, dw->dma.cap_mask);
        dma_cap_set(DMA_MEMCPY, dw->dma.cap_mask);

        dw->dma.dev = chip->dev;
        dw->dma.device_alloc_chan_resources = dwc_alloc_chan_resources;
        dw->dma.device_free_chan_resources = dwc_free_chan_resources;

        dw->dma.device_prep_dma_memcpy = dwc_prep_dma_memcpy;
        dw->dma.device_prep_slave_sg = dwc_prep_slave_sg;

        dw->dma.device_caps = dwc_caps;
        dw->dma.device_config = dwc_config;
        dw->dma.device_pause = dwc_pause;
        dw->dma.device_resume = dwc_resume;
        dw->dma.device_terminate_all = dwc_terminate_all;

        dw->dma.device_tx_status = dwc_tx_status;
        dw->dma.device_issue_pending = dwc_issue_pending;

        /* DMA capabilities */
        dw->dma.min_burst = DW_DMA_MIN_BURST;
        dw->dma.max_burst = DW_DMA_MAX_BURST;
        dw->dma.src_addr_widths = DW_DMA_BUSWIDTHS;
        dw->dma.dst_addr_widths = DW_DMA_BUSWIDTHS;
        dw->dma.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
                             BIT(DMA_MEM_TO_MEM);
        dw->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;

        /*
         * For now there is no hardware with non uniform maximum block size
         * across all of the device channels, so we set the maximum segment
         * size as the block size found for the very first channel.
         */
        dma_set_max_seg_size(dw->dma.dev, dw->chan[0].block_size);

        err = dma_async_device_register(&dw->dma);
        if (err)
                goto err_dma_register;

        dev_info(chip->dev, "DesignWare DMA Controller, %d channels\n",
                 pdata->nr_channels);

        pm_runtime_put_sync_suspend(chip->dev);

        return 0;

err_dma_register:
        free_irq(chip->irq, dw);
err_pdata:
        pm_runtime_put_sync_suspend(chip->dev);
        return err;
}

int do_dma_remove(struct dw_dma_chip *chip)
{
        struct dw_dma           *dw = chip->dw;
        struct dw_dma_chan      *dwc, *_dwc;

        pm_runtime_get_sync(chip->dev);

        do_dw_dma_off(dw);
        dma_async_device_unregister(&dw->dma);

        free_irq(chip->irq, dw);
        tasklet_kill(&dw->tasklet);

        list_for_each_entry_safe(dwc, _dwc, &dw->dma.channels,
                        chan.device_node) {
                list_del(&dwc->chan.device_node);
                channel_clear_bit(dw, CH_EN, dwc->mask);
        }

        pm_runtime_put_sync_suspend(chip->dev);
        return 0;
}

int do_dw_dma_disable(struct dw_dma_chip *chip)
{
        struct dw_dma *dw = chip->dw;

        dw->disable(dw);
        return 0;
}
EXPORT_SYMBOL_GPL(do_dw_dma_disable);

int do_dw_dma_enable(struct dw_dma_chip *chip)
{
        struct dw_dma *dw = chip->dw;

        dw->enable(dw);
        return 0;
}
EXPORT_SYMBOL_GPL(do_dw_dma_enable);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Synopsys DesignWare DMA Controller core driver");
MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");