// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Analog Devices AXI-DMAC core
 *
 * Copyright 2013-2019 Analog Devices Inc.
 *  Author: Lars-Peter Clausen <lars@metafoo.de>
 */

#include <linux/clk.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/fpga/adi-axi-common.h>

#include <dt-bindings/dma/axi-dmac.h>

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

/*
 * The AXI-DMAC is a soft IP core that is used in FPGA designs. The core has
 * various instantiation parameters which decided the exact feature set support
 * by the core.
 *
 * Each channel of the core has a source interface and a destination interface.
 * The number of channels and the type of the channel interfaces is selected at
 * configuration time. A interface can either be a connected to a central memory
 * interconnect, which allows access to system memory, or it can be connected to
 * a dedicated bus which is directly connected to a data port on a peripheral.
 * Given that those are configuration options of the core that are selected when
 * it is instantiated this means that they can not be changed by software at
 * runtime. By extension this means that each channel is uni-directional. It can
 * either be device to memory or memory to device, but not both. Also since the
 * device side is a dedicated data bus only connected to a single peripheral
 * there is no address than can or needs to be configured for the device side.
 */

#define AXI_DMAC_REG_IRQ_MASK           0x80
#define AXI_DMAC_REG_IRQ_PENDING        0x84
#define AXI_DMAC_REG_IRQ_SOURCE         0x88

#define AXI_DMAC_REG_CTRL               0x400
#define AXI_DMAC_REG_TRANSFER_ID        0x404
#define AXI_DMAC_REG_START_TRANSFER     0x408
#define AXI_DMAC_REG_FLAGS              0x40c
#define AXI_DMAC_REG_DEST_ADDRESS       0x410
#define AXI_DMAC_REG_SRC_ADDRESS        0x414
#define AXI_DMAC_REG_X_LENGTH           0x418
#define AXI_DMAC_REG_Y_LENGTH           0x41c
#define AXI_DMAC_REG_DEST_STRIDE        0x420
#define AXI_DMAC_REG_SRC_STRIDE         0x424
#define AXI_DMAC_REG_TRANSFER_DONE      0x428
#define AXI_DMAC_REG_ACTIVE_TRANSFER_ID 0x42c
#define AXI_DMAC_REG_STATUS             0x430
#define AXI_DMAC_REG_CURRENT_SRC_ADDR   0x434
#define AXI_DMAC_REG_CURRENT_DEST_ADDR  0x438
#define AXI_DMAC_REG_PARTIAL_XFER_LEN   0x44c
#define AXI_DMAC_REG_PARTIAL_XFER_ID    0x450

#define AXI_DMAC_CTRL_ENABLE            BIT(0)
#define AXI_DMAC_CTRL_PAUSE             BIT(1)

#define AXI_DMAC_IRQ_SOT                BIT(0)
#define AXI_DMAC_IRQ_EOT                BIT(1)

#define AXI_DMAC_FLAG_CYCLIC            BIT(0)
#define AXI_DMAC_FLAG_LAST              BIT(1)
#define AXI_DMAC_FLAG_PARTIAL_REPORT    BIT(2)

#define AXI_DMAC_FLAG_PARTIAL_XFER_DONE BIT(31)

/* The maximum ID allocated by the hardware is 31 */
#define AXI_DMAC_SG_UNUSED 32U

struct axi_dmac_sg {
        dma_addr_t src_addr;
        dma_addr_t dest_addr;
        unsigned int x_len;
        unsigned int y_len;
        unsigned int dest_stride;
        unsigned int src_stride;
        unsigned int id;
        unsigned int partial_len;
        bool schedule_when_free;
};

struct axi_dmac_desc {
        struct virt_dma_desc vdesc;
        bool cyclic;
        bool have_partial_xfer;

        unsigned int num_submitted;
        unsigned int num_completed;
        unsigned int num_sgs;
        struct axi_dmac_sg sg[];
};

struct axi_dmac_chan {
        struct virt_dma_chan vchan;

        struct axi_dmac_desc *next_desc;
        struct list_head active_descs;
        enum dma_transfer_direction direction;

        unsigned int src_width;
        unsigned int dest_width;
        unsigned int src_type;
        unsigned int dest_type;

        unsigned int max_length;
        unsigned int address_align_mask;
        unsigned int length_align_mask;

        bool hw_partial_xfer;
        bool hw_cyclic;
        bool hw_2d;
};

struct axi_dmac {
        void __iomem *base;
        int irq;

        struct clk *clk;

        struct dma_device dma_dev;
        struct axi_dmac_chan chan;

        struct device_dma_parameters dma_parms;
};

static struct axi_dmac *chan_to_axi_dmac(struct axi_dmac_chan *chan)
{
        return container_of(chan->vchan.chan.device, struct axi_dmac,
                dma_dev);
}

static struct axi_dmac_chan *to_axi_dmac_chan(struct dma_chan *c)
{
        return container_of(c, struct axi_dmac_chan, vchan.chan);
}

static struct axi_dmac_desc *to_axi_dmac_desc(struct virt_dma_desc *vdesc)
{
        return container_of(vdesc, struct axi_dmac_desc, vdesc);
}

static void axi_dmac_write(struct axi_dmac *axi_dmac, unsigned int reg,
        unsigned int val)
{
        writel(val, axi_dmac->base + reg);
}

static int axi_dmac_read(struct axi_dmac *axi_dmac, unsigned int reg)
{
        return readl(axi_dmac->base + reg);
}

static int axi_dmac_src_is_mem(struct axi_dmac_chan *chan)
{
        return chan->src_type == AXI_DMAC_BUS_TYPE_AXI_MM;
}

static int axi_dmac_dest_is_mem(struct axi_dmac_chan *chan)
{
        return chan->dest_type == AXI_DMAC_BUS_TYPE_AXI_MM;
}

static bool axi_dmac_check_len(struct axi_dmac_chan *chan, unsigned int len)
{
        if (len == 0)
                return false;
        if ((len & chan->length_align_mask) != 0) /* Not aligned */
                return false;
        return true;
}

static bool axi_dmac_check_addr(struct axi_dmac_chan *chan, dma_addr_t addr)
{
        if ((addr & chan->address_align_mask) != 0) /* Not aligned */
                return false;
        return true;
}

static void axi_dmac_start_transfer(struct axi_dmac_chan *chan)
{
        struct axi_dmac *dmac = chan_to_axi_dmac(chan);
        struct virt_dma_desc *vdesc;
        struct axi_dmac_desc *desc;
        struct axi_dmac_sg *sg;
        unsigned int flags = 0;
        unsigned int val;

        val = axi_dmac_read(dmac, AXI_DMAC_REG_START_TRANSFER);
        if (val) /* Queue is full, wait for the next SOT IRQ */
                return;

        desc = chan->next_desc;

        if (!desc) {
                vdesc = vchan_next_desc(&chan->vchan);
                if (!vdesc)
                        return;
                list_move_tail(&vdesc->node, &chan->active_descs);
                desc = to_axi_dmac_desc(vdesc);
        }
        sg = &desc->sg[desc->num_submitted];

        /* Already queued in cyclic mode. Wait for it to finish */
        if (sg->id != AXI_DMAC_SG_UNUSED) {
                sg->schedule_when_free = true;
                return;
        }

        desc->num_submitted++;
        if (desc->num_submitted == desc->num_sgs ||
            desc->have_partial_xfer) {
                if (desc->cyclic)
                        desc->num_submitted = 0; /* Start again */
                else
                        chan->next_desc = NULL;
                flags |= AXI_DMAC_FLAG_LAST;
        } else {
                chan->next_desc = desc;
        }

        sg->id = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_ID);

        if (axi_dmac_dest_is_mem(chan)) {
                axi_dmac_write(dmac, AXI_DMAC_REG_DEST_ADDRESS, sg->dest_addr);
                axi_dmac_write(dmac, AXI_DMAC_REG_DEST_STRIDE, sg->dest_stride);
        }

        if (axi_dmac_src_is_mem(chan)) {
                axi_dmac_write(dmac, AXI_DMAC_REG_SRC_ADDRESS, sg->src_addr);
                axi_dmac_write(dmac, AXI_DMAC_REG_SRC_STRIDE, sg->src_stride);
        }

        /*
         * If the hardware supports cyclic transfers and there is no callback to
         * call and only a single segment, enable hw cyclic mode to avoid
         * unnecessary interrupts.
         */
        if (chan->hw_cyclic && desc->cyclic && !desc->vdesc.tx.callback &&
                desc->num_sgs == 1)
                flags |= AXI_DMAC_FLAG_CYCLIC;

        if (chan->hw_partial_xfer)
                flags |= AXI_DMAC_FLAG_PARTIAL_REPORT;

        axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, sg->x_len - 1);
        axi_dmac_write(dmac, AXI_DMAC_REG_Y_LENGTH, sg->y_len - 1);
        axi_dmac_write(dmac, AXI_DMAC_REG_FLAGS, flags);
        axi_dmac_write(dmac, AXI_DMAC_REG_START_TRANSFER, 1);
}

static struct axi_dmac_desc *axi_dmac_active_desc(struct axi_dmac_chan *chan)
{
        return list_first_entry_or_null(&chan->active_descs,
                struct axi_dmac_desc, vdesc.node);
}

static inline unsigned int axi_dmac_total_sg_bytes(struct axi_dmac_chan *chan,
        struct axi_dmac_sg *sg)
{
        if (chan->hw_2d)
                return sg->x_len * sg->y_len;
        else
                return sg->x_len;
}

static void axi_dmac_dequeue_partial_xfers(struct axi_dmac_chan *chan)
{
        struct axi_dmac *dmac = chan_to_axi_dmac(chan);
        struct axi_dmac_desc *desc;
        struct axi_dmac_sg *sg;
        u32 xfer_done, len, id, i;
        bool found_sg;

        do {
                len = axi_dmac_read(dmac, AXI_DMAC_REG_PARTIAL_XFER_LEN);
                id  = axi_dmac_read(dmac, AXI_DMAC_REG_PARTIAL_XFER_ID);

                found_sg = false;
                list_for_each_entry(desc, &chan->active_descs, vdesc.node) {
                        for (i = 0; i < desc->num_sgs; i++) {
                                sg = &desc->sg[i];
                                if (sg->id == AXI_DMAC_SG_UNUSED)
                                        continue;
                                if (sg->id == id) {
                                        desc->have_partial_xfer = true;
                                        sg->partial_len = len;
                                        found_sg = true;
                                        break;
                                }
                        }
                        if (found_sg)
                                break;
                }

                if (found_sg) {
                        dev_dbg(dmac->dma_dev.dev,
                                "Found partial segment id=%u, len=%u\n",
                                id, len);
                } else {
                        dev_warn(dmac->dma_dev.dev,
                                 "Not found partial segment id=%u, len=%u\n",
                                 id, len);
                }

                /* Check if we have any more partial transfers */
                xfer_done = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_DONE);
                xfer_done = !(xfer_done & AXI_DMAC_FLAG_PARTIAL_XFER_DONE);

        } while (!xfer_done);
}

static void axi_dmac_compute_residue(struct axi_dmac_chan *chan,
        struct axi_dmac_desc *active)
{
        struct dmaengine_result *rslt = &active->vdesc.tx_result;
        unsigned int start = active->num_completed - 1;
        struct axi_dmac_sg *sg;
        unsigned int i, total;

        rslt->result = DMA_TRANS_NOERROR;
        rslt->residue = 0;

        /*
         * We get here if the last completed segment is partial, which
         * means we can compute the residue from that segment onwards
         */
        for (i = start; i < active->num_sgs; i++) {
                sg = &active->sg[i];
                total = axi_dmac_total_sg_bytes(chan, sg);
                rslt->residue += (total - sg->partial_len);
        }
}

static bool axi_dmac_transfer_done(struct axi_dmac_chan *chan,
        unsigned int completed_transfers)
{
        struct axi_dmac_desc *active;
        struct axi_dmac_sg *sg;
        bool start_next = false;

        active = axi_dmac_active_desc(chan);
        if (!active)
                return false;

        if (chan->hw_partial_xfer &&
            (completed_transfers & AXI_DMAC_FLAG_PARTIAL_XFER_DONE))
                axi_dmac_dequeue_partial_xfers(chan);

        do {
                sg = &active->sg[active->num_completed];
                if (sg->id == AXI_DMAC_SG_UNUSED) /* Not yet submitted */
                        break;
                if (!(BIT(sg->id) & completed_transfers))
                        break;
                active->num_completed++;
                sg->id = AXI_DMAC_SG_UNUSED;
                if (sg->schedule_when_free) {
                        sg->schedule_when_free = false;
                        start_next = true;
                }

                if (sg->partial_len)
                        axi_dmac_compute_residue(chan, active);

                if (active->cyclic)
                        vchan_cyclic_callback(&active->vdesc);

                if (active->num_completed == active->num_sgs ||
                    sg->partial_len) {
                        if (active->cyclic) {
                                active->num_completed = 0; /* wrap around */
                        } else {
                                list_del(&active->vdesc.node);
                                vchan_cookie_complete(&active->vdesc);
                                active = axi_dmac_active_desc(chan);
                        }
                }
        } while (active);

        return start_next;
}

static irqreturn_t axi_dmac_interrupt_handler(int irq, void *devid)
{
        struct axi_dmac *dmac = devid;
        unsigned int pending;
        bool start_next = false;

        pending = axi_dmac_read(dmac, AXI_DMAC_REG_IRQ_PENDING);
        if (!pending)
                return IRQ_NONE;

        axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_PENDING, pending);

        spin_lock(&dmac->chan.vchan.lock);
        /* One or more transfers have finished */
        if (pending & AXI_DMAC_IRQ_EOT) {
                unsigned int completed;

                completed = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_DONE);
                start_next = axi_dmac_transfer_done(&dmac->chan, completed);
        }
        /* Space has become available in the descriptor queue */
        if ((pending & AXI_DMAC_IRQ_SOT) || start_next)
                axi_dmac_start_transfer(&dmac->chan);
        spin_unlock(&dmac->chan.vchan.lock);

        return IRQ_HANDLED;
}

static int axi_dmac_terminate_all(struct dma_chan *c)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
        struct axi_dmac *dmac = chan_to_axi_dmac(chan);
        unsigned long flags;
        LIST_HEAD(head);

        spin_lock_irqsave(&chan->vchan.lock, flags);
        axi_dmac_write(dmac, AXI_DMAC_REG_CTRL, 0);
        chan->next_desc = NULL;
        vchan_get_all_descriptors(&chan->vchan, &head);
        list_splice_tail_init(&chan->active_descs, &head);
        spin_unlock_irqrestore(&chan->vchan.lock, flags);

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

        return 0;
}

static void axi_dmac_synchronize(struct dma_chan *c)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);

        vchan_synchronize(&chan->vchan);
}

static void axi_dmac_issue_pending(struct dma_chan *c)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
        struct axi_dmac *dmac = chan_to_axi_dmac(chan);
        unsigned long flags;

        axi_dmac_write(dmac, AXI_DMAC_REG_CTRL, AXI_DMAC_CTRL_ENABLE);

        spin_lock_irqsave(&chan->vchan.lock, flags);
        if (vchan_issue_pending(&chan->vchan))
                axi_dmac_start_transfer(chan);
        spin_unlock_irqrestore(&chan->vchan.lock, flags);
}

static struct axi_dmac_desc *axi_dmac_alloc_desc(unsigned int num_sgs)
{
        struct axi_dmac_desc *desc;
        unsigned int i;

        desc = kzalloc(struct_size(desc, sg, num_sgs), GFP_NOWAIT);
        if (!desc)
                return NULL;

        for (i = 0; i < num_sgs; i++)
                desc->sg[i].id = AXI_DMAC_SG_UNUSED;

        desc->num_sgs = num_sgs;

        return desc;
}

static struct axi_dmac_sg *axi_dmac_fill_linear_sg(struct axi_dmac_chan *chan,
        enum dma_transfer_direction direction, dma_addr_t addr,
        unsigned int num_periods, unsigned int period_len,
        struct axi_dmac_sg *sg)
{
        unsigned int num_segments, i;
        unsigned int segment_size;
        unsigned int len;

        /* Split into multiple equally sized segments if necessary */
        num_segments = DIV_ROUND_UP(period_len, chan->max_length);
        segment_size = DIV_ROUND_UP(period_len, num_segments);
        /* Take care of alignment */
        segment_size = ((segment_size - 1) | chan->length_align_mask) + 1;

        for (i = 0; i < num_periods; i++) {
                len = period_len;

                while (len > segment_size) {
                        if (direction == DMA_DEV_TO_MEM)
                                sg->dest_addr = addr;
                        else
                                sg->src_addr = addr;
                        sg->x_len = segment_size;
                        sg->y_len = 1;
                        sg++;
                        addr += segment_size;
                        len -= segment_size;
                }

                if (direction == DMA_DEV_TO_MEM)
                        sg->dest_addr = addr;
                else
                        sg->src_addr = addr;
                sg->x_len = len;
                sg->y_len = 1;
                sg++;
                addr += len;
        }

        return sg;
}

static struct dma_async_tx_descriptor *axi_dmac_prep_slave_sg(
        struct dma_chan *c, struct scatterlist *sgl,
        unsigned int sg_len, enum dma_transfer_direction direction,
        unsigned long flags, void *context)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
        struct axi_dmac_desc *desc;
        struct axi_dmac_sg *dsg;
        struct scatterlist *sg;
        unsigned int num_sgs;
        unsigned int i;

        if (direction != chan->direction)
                return NULL;

        num_sgs = 0;
        for_each_sg(sgl, sg, sg_len, i)
                num_sgs += DIV_ROUND_UP(sg_dma_len(sg), chan->max_length);

        desc = axi_dmac_alloc_desc(num_sgs);
        if (!desc)
                return NULL;

        dsg = desc->sg;

        for_each_sg(sgl, sg, sg_len, i) {
                if (!axi_dmac_check_addr(chan, sg_dma_address(sg)) ||
                    !axi_dmac_check_len(chan, sg_dma_len(sg))) {
                        kfree(desc);
                        return NULL;
                }

                dsg = axi_dmac_fill_linear_sg(chan, direction, sg_dma_address(sg), 1,
                        sg_dma_len(sg), dsg);
        }

        desc->cyclic = false;

        return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
}

static struct dma_async_tx_descriptor *axi_dmac_prep_dma_cyclic(
        struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
        size_t period_len, enum dma_transfer_direction direction,
        unsigned long flags)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
        struct axi_dmac_desc *desc;
        unsigned int num_periods, num_segments;

        if (direction != chan->direction)
                return NULL;

        if (!axi_dmac_check_len(chan, buf_len) ||
            !axi_dmac_check_addr(chan, buf_addr))
                return NULL;

        if (period_len == 0 || buf_len % period_len)
                return NULL;

        num_periods = buf_len / period_len;
        num_segments = DIV_ROUND_UP(period_len, chan->max_length);

        desc = axi_dmac_alloc_desc(num_periods * num_segments);
        if (!desc)
                return NULL;

        axi_dmac_fill_linear_sg(chan, direction, buf_addr, num_periods,
                period_len, desc->sg);

        desc->cyclic = true;

        return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
}

static struct dma_async_tx_descriptor *axi_dmac_prep_interleaved(
        struct dma_chan *c, struct dma_interleaved_template *xt,
        unsigned long flags)
{
        struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
        struct axi_dmac_desc *desc;
        size_t dst_icg, src_icg;

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

        if (xt->dir != chan->direction)
                return NULL;

        if (axi_dmac_src_is_mem(chan)) {
                if (!xt->src_inc || !axi_dmac_check_addr(chan, xt->src_start))
                        return NULL;
        }

        if (axi_dmac_dest_is_mem(chan)) {
                if (!xt->dst_inc || !axi_dmac_check_addr(chan, xt->dst_start))
                        return NULL;
        }

        dst_icg = dmaengine_get_dst_icg(xt, &xt->sgl[0]);
        src_icg = dmaengine_get_src_icg(xt, &xt->sgl[0]);

        if (chan->hw_2d) {
                if (!axi_dmac_check_len(chan, xt->sgl[0].size) ||
                    xt->numf == 0)
                        return NULL;
                if (xt->sgl[0].size + dst_icg > chan->max_length ||
                    xt->sgl[0].size + src_icg > chan->max_length)
                        return NULL;
        } else {
                if (dst_icg != 0 || src_icg != 0)
                        return NULL;
                if (chan->max_length / xt->sgl[0].size < xt->numf)
                        return NULL;
                if (!axi_dmac_check_len(chan, xt->sgl[0].size * xt->numf))
                        return NULL;
        }

        desc = axi_dmac_alloc_desc(1);
        if (!desc)
                return NULL;

        if (axi_dmac_src_is_mem(chan)) {
                desc->sg[0].src_addr = xt->src_start;
                desc->sg[0].src_stride = xt->sgl[0].size + src_icg;
        }

        if (axi_dmac_dest_is_mem(chan)) {
                desc->sg[0].dest_addr = xt->dst_start;
                desc->sg[0].dest_stride = xt->sgl[0].size + dst_icg;
        }

        if (chan->hw_2d) {
                desc->sg[0].x_len = xt->sgl[0].size;
                desc->sg[0].y_len = xt->numf;
        } else {
                desc->sg[0].x_len = xt->sgl[0].size * xt->numf;
                desc->sg[0].y_len = 1;
        }

        if (flags & DMA_CYCLIC)
                desc->cyclic = true;

        return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
}

static void axi_dmac_free_chan_resources(struct dma_chan *c)
{
        vchan_free_chan_resources(to_virt_chan(c));
}

static void axi_dmac_desc_free(struct virt_dma_desc *vdesc)
{
        kfree(container_of(vdesc, struct axi_dmac_desc, vdesc));
}

static bool axi_dmac_regmap_rdwr(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case AXI_DMAC_REG_IRQ_MASK:
        case AXI_DMAC_REG_IRQ_SOURCE:
        case AXI_DMAC_REG_IRQ_PENDING:
        case AXI_DMAC_REG_CTRL:
        case AXI_DMAC_REG_TRANSFER_ID:
        case AXI_DMAC_REG_START_TRANSFER:
        case AXI_DMAC_REG_FLAGS:
        case AXI_DMAC_REG_DEST_ADDRESS:
        case AXI_DMAC_REG_SRC_ADDRESS:
        case AXI_DMAC_REG_X_LENGTH:
        case AXI_DMAC_REG_Y_LENGTH:
        case AXI_DMAC_REG_DEST_STRIDE:
        case AXI_DMAC_REG_SRC_STRIDE:
        case AXI_DMAC_REG_TRANSFER_DONE:
        case AXI_DMAC_REG_ACTIVE_TRANSFER_ID:
        case AXI_DMAC_REG_STATUS:
        case AXI_DMAC_REG_CURRENT_SRC_ADDR:
        case AXI_DMAC_REG_CURRENT_DEST_ADDR:
        case AXI_DMAC_REG_PARTIAL_XFER_LEN:
        case AXI_DMAC_REG_PARTIAL_XFER_ID:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config axi_dmac_regmap_config = {
        .reg_bits = 32,
        .val_bits = 32,
        .reg_stride = 4,
        .max_register = AXI_DMAC_REG_PARTIAL_XFER_ID,
        .readable_reg = axi_dmac_regmap_rdwr,
        .writeable_reg = axi_dmac_regmap_rdwr,
};

/*
 * The configuration stored in the devicetree matches the configuration
 * parameters of the peripheral instance and allows the driver to know which
 * features are implemented and how it should behave.
 */
static int axi_dmac_parse_chan_dt(struct device_node *of_chan,
        struct axi_dmac_chan *chan)
{
        u32 val;
        int ret;

        ret = of_property_read_u32(of_chan, "reg", &val);
        if (ret)
                return ret;

        /* We only support 1 channel for now */
        if (val != 0)
                return -EINVAL;

        ret = of_property_read_u32(of_chan, "adi,source-bus-type", &val);
        if (ret)
                return ret;
        if (val > AXI_DMAC_BUS_TYPE_FIFO)
                return -EINVAL;
        chan->src_type = val;

        ret = of_property_read_u32(of_chan, "adi,destination-bus-type", &val);
        if (ret)
                return ret;
        if (val > AXI_DMAC_BUS_TYPE_FIFO)
                return -EINVAL;
        chan->dest_type = val;

        ret = of_property_read_u32(of_chan, "adi,source-bus-width", &val);
        if (ret)
                return ret;
        chan->src_width = val / 8;

        ret = of_property_read_u32(of_chan, "adi,destination-bus-width", &val);
        if (ret)
                return ret;
        chan->dest_width = val / 8;

        chan->address_align_mask = max(chan->dest_width, chan->src_width) - 1;

        if (axi_dmac_dest_is_mem(chan) && axi_dmac_src_is_mem(chan))
                chan->direction = DMA_MEM_TO_MEM;
        else if (!axi_dmac_dest_is_mem(chan) && axi_dmac_src_is_mem(chan))
                chan->direction = DMA_MEM_TO_DEV;
        else if (axi_dmac_dest_is_mem(chan) && !axi_dmac_src_is_mem(chan))
                chan->direction = DMA_DEV_TO_MEM;
        else
                chan->direction = DMA_DEV_TO_DEV;

        return 0;
}

static int axi_dmac_detect_caps(struct axi_dmac *dmac)
{
        struct axi_dmac_chan *chan = &dmac->chan;
        unsigned int version;

        version = axi_dmac_read(dmac, ADI_AXI_REG_VERSION);

        axi_dmac_write(dmac, AXI_DMAC_REG_FLAGS, AXI_DMAC_FLAG_CYCLIC);
        if (axi_dmac_read(dmac, AXI_DMAC_REG_FLAGS) == AXI_DMAC_FLAG_CYCLIC)
                chan->hw_cyclic = true;

        axi_dmac_write(dmac, AXI_DMAC_REG_Y_LENGTH, 1);
        if (axi_dmac_read(dmac, AXI_DMAC_REG_Y_LENGTH) == 1)
                chan->hw_2d = true;

        axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, 0xffffffff);
        chan->max_length = axi_dmac_read(dmac, AXI_DMAC_REG_X_LENGTH);
        if (chan->max_length != UINT_MAX)
                chan->max_length++;

        axi_dmac_write(dmac, AXI_DMAC_REG_DEST_ADDRESS, 0xffffffff);
        if (axi_dmac_read(dmac, AXI_DMAC_REG_DEST_ADDRESS) == 0 &&
            chan->dest_type == AXI_DMAC_BUS_TYPE_AXI_MM) {
                dev_err(dmac->dma_dev.dev,
                        "Destination memory-mapped interface not supported.");
                return -ENODEV;
        }

        axi_dmac_write(dmac, AXI_DMAC_REG_SRC_ADDRESS, 0xffffffff);
        if (axi_dmac_read(dmac, AXI_DMAC_REG_SRC_ADDRESS) == 0 &&
            chan->src_type == AXI_DMAC_BUS_TYPE_AXI_MM) {
                dev_err(dmac->dma_dev.dev,
                        "Source memory-mapped interface not supported.");
                return -ENODEV;
        }

        if (version >= ADI_AXI_PCORE_VER(4, 2, 'a'))
                chan->hw_partial_xfer = true;

        if (version >= ADI_AXI_PCORE_VER(4, 1, 'a')) {
                axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, 0x00);
                chan->length_align_mask =
                        axi_dmac_read(dmac, AXI_DMAC_REG_X_LENGTH);
        } else {
                chan->length_align_mask = chan->address_align_mask;
        }

        return 0;
}

static int axi_dmac_probe(struct platform_device *pdev)
{
        struct device_node *of_channels, *of_chan;
        struct dma_device *dma_dev;
        struct axi_dmac *dmac;
        struct resource *res;
        int ret;

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

        dmac->irq = platform_get_irq(pdev, 0);
        if (dmac->irq < 0)
                return dmac->irq;
        if (dmac->irq == 0)
                return -EINVAL;

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

        dmac->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(dmac->clk))
                return PTR_ERR(dmac->clk);

        INIT_LIST_HEAD(&dmac->chan.active_descs);

        of_channels = of_get_child_by_name(pdev->dev.of_node, "adi,channels");
        if (of_channels == NULL)
                return -ENODEV;

        for_each_child_of_node(of_channels, of_chan) {
                ret = axi_dmac_parse_chan_dt(of_chan, &dmac->chan);
                if (ret) {
                        of_node_put(of_chan);
                        of_node_put(of_channels);
                        return -EINVAL;
                }
        }
        of_node_put(of_channels);

        pdev->dev.dma_parms = &dmac->dma_parms;
        dma_set_max_seg_size(&pdev->dev, UINT_MAX);

        dma_dev = &dmac->dma_dev;
        dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
        dma_cap_set(DMA_CYCLIC, dma_dev->cap_mask);
        dma_cap_set(DMA_INTERLEAVE, dma_dev->cap_mask);
        dma_dev->device_free_chan_resources = axi_dmac_free_chan_resources;
        dma_dev->device_tx_status = dma_cookie_status;
        dma_dev->device_issue_pending = axi_dmac_issue_pending;
        dma_dev->device_prep_slave_sg = axi_dmac_prep_slave_sg;
        dma_dev->device_prep_dma_cyclic = axi_dmac_prep_dma_cyclic;
        dma_dev->device_prep_interleaved_dma = axi_dmac_prep_interleaved;
        dma_dev->device_terminate_all = axi_dmac_terminate_all;
        dma_dev->device_synchronize = axi_dmac_synchronize;
        dma_dev->dev = &pdev->dev;
        dma_dev->chancnt = 1;
        dma_dev->src_addr_widths = BIT(dmac->chan.src_width);
        dma_dev->dst_addr_widths = BIT(dmac->chan.dest_width);
        dma_dev->directions = BIT(dmac->chan.direction);
        dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
        INIT_LIST_HEAD(&dma_dev->channels);

        dmac->chan.vchan.desc_free = axi_dmac_desc_free;
        vchan_init(&dmac->chan.vchan, dma_dev);

        ret = clk_prepare_enable(dmac->clk);
        if (ret < 0)
                return ret;

        ret = axi_dmac_detect_caps(dmac);
        if (ret)
                goto err_clk_disable;

        dma_dev->copy_align = (dmac->chan.address_align_mask + 1);

        axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);

        ret = dma_async_device_register(dma_dev);
        if (ret)
                goto err_clk_disable;

        ret = of_dma_controller_register(pdev->dev.of_node,
                of_dma_xlate_by_chan_id, dma_dev);
        if (ret)
                goto err_unregister_device;

        ret = request_irq(dmac->irq, axi_dmac_interrupt_handler, IRQF_SHARED,
                dev_name(&pdev->dev), dmac);
        if (ret)
                goto err_unregister_of;

        platform_set_drvdata(pdev, dmac);

        devm_regmap_init_mmio(&pdev->dev, dmac->base, &axi_dmac_regmap_config);

        return 0;

err_unregister_of:
        of_dma_controller_free(pdev->dev.of_node);
err_unregister_device:
        dma_async_device_unregister(&dmac->dma_dev);
err_clk_disable:
        clk_disable_unprepare(dmac->clk);

        return ret;
}

static int axi_dmac_remove(struct platform_device *pdev)
{
        struct axi_dmac *dmac = platform_get_drvdata(pdev);

        of_dma_controller_free(pdev->dev.of_node);
        free_irq(dmac->irq, dmac);
        tasklet_kill(&dmac->chan.vchan.task);
        dma_async_device_unregister(&dmac->dma_dev);
        clk_disable_unprepare(dmac->clk);

        return 0;
}

static const struct of_device_id axi_dmac_of_match_table[] = {
        { .compatible = "adi,axi-dmac-1.00.a" },
        { },
};
MODULE_DEVICE_TABLE(of, axi_dmac_of_match_table);

static struct platform_driver axi_dmac_driver = {
        .driver = {
                .name = "dma-axi-dmac",
                .of_match_table = axi_dmac_of_match_table,
        },
        .probe = axi_dmac_probe,
        .remove = axi_dmac_remove,
};
module_platform_driver(axi_dmac_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("DMA controller driver for the AXI-DMAC controller");
MODULE_LICENSE("GPL v2");