root/drivers/dma/arm-dma350.c
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2024-2025 Arm Limited
// Arm DMA-350 driver

#include <linux/bitfield.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/module.h>
#include <linux/platform_device.h>

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

#define DMAINFO                 0x0f00

#define DMA_BUILDCFG0           0xb0
#define DMA_CFG_DATA_WIDTH      GENMASK(18, 16)
#define DMA_CFG_ADDR_WIDTH      GENMASK(15, 10)
#define DMA_CFG_NUM_CHANNELS    GENMASK(9, 4)

#define DMA_BUILDCFG1           0xb4
#define DMA_CFG_NUM_TRIGGER_IN  GENMASK(8, 0)

#define IIDR                    0xc8
#define IIDR_PRODUCTID          GENMASK(31, 20)
#define IIDR_VARIANT            GENMASK(19, 16)
#define IIDR_REVISION           GENMASK(15, 12)
#define IIDR_IMPLEMENTER        GENMASK(11, 0)

#define PRODUCTID_DMA350        0x3a0
#define IMPLEMENTER_ARM         0x43b

#define DMACH(n)                (0x1000 + 0x0100 * (n))

#define CH_CMD                  0x00
#define CH_CMD_RESUME           BIT(5)
#define CH_CMD_PAUSE            BIT(4)
#define CH_CMD_STOP             BIT(3)
#define CH_CMD_DISABLE          BIT(2)
#define CH_CMD_CLEAR            BIT(1)
#define CH_CMD_ENABLE           BIT(0)

#define CH_STATUS               0x04
#define CH_STAT_RESUMEWAIT      BIT(21)
#define CH_STAT_PAUSED          BIT(20)
#define CH_STAT_STOPPED         BIT(19)
#define CH_STAT_DISABLED        BIT(18)
#define CH_STAT_ERR             BIT(17)
#define CH_STAT_DONE            BIT(16)
#define CH_STAT_INTR_ERR        BIT(1)
#define CH_STAT_INTR_DONE       BIT(0)

#define CH_INTREN               0x08
#define CH_INTREN_ERR           BIT(1)
#define CH_INTREN_DONE          BIT(0)

#define CH_CTRL                 0x0c
#define CH_CTRL_USEDESTRIGIN    BIT(26)
#define CH_CTRL_USESRCTRIGIN    BIT(26)
#define CH_CTRL_DONETYPE        GENMASK(23, 21)
#define CH_CTRL_REGRELOADTYPE   GENMASK(20, 18)
#define CH_CTRL_XTYPE           GENMASK(11, 9)
#define CH_CTRL_TRANSIZE        GENMASK(2, 0)

#define CH_SRCADDR              0x10
#define CH_SRCADDRHI            0x14
#define CH_DESADDR              0x18
#define CH_DESADDRHI            0x1c
#define CH_XSIZE                0x20
#define CH_XSIZEHI              0x24
#define CH_SRCTRANSCFG          0x28
#define CH_DESTRANSCFG          0x2c
#define CH_CFG_MAXBURSTLEN      GENMASK(19, 16)
#define CH_CFG_PRIVATTR         BIT(11)
#define CH_CFG_SHAREATTR        GENMASK(9, 8)
#define CH_CFG_MEMATTR          GENMASK(7, 0)

#define TRANSCFG_DEVICE                                 \
        FIELD_PREP(CH_CFG_MAXBURSTLEN, 0xf) |           \
        FIELD_PREP(CH_CFG_SHAREATTR, SHAREATTR_OSH) |   \
        FIELD_PREP(CH_CFG_MEMATTR, MEMATTR_DEVICE)
#define TRANSCFG_NC                                     \
        FIELD_PREP(CH_CFG_MAXBURSTLEN, 0xf) |           \
        FIELD_PREP(CH_CFG_SHAREATTR, SHAREATTR_OSH) |   \
        FIELD_PREP(CH_CFG_MEMATTR, MEMATTR_NC)
#define TRANSCFG_WB                                     \
        FIELD_PREP(CH_CFG_MAXBURSTLEN, 0xf) |           \
        FIELD_PREP(CH_CFG_SHAREATTR, SHAREATTR_ISH) |   \
        FIELD_PREP(CH_CFG_MEMATTR, MEMATTR_WB)

#define CH_XADDRINC             0x30
#define CH_XY_DES               GENMASK(31, 16)
#define CH_XY_SRC               GENMASK(15, 0)

#define CH_FILLVAL              0x38
#define CH_SRCTRIGINCFG         0x4c
#define CH_DESTRIGINCFG         0x50
#define CH_LINKATTR             0x70
#define CH_LINK_SHAREATTR       GENMASK(9, 8)
#define CH_LINK_MEMATTR         GENMASK(7, 0)

#define CH_AUTOCFG              0x74
#define CH_LINKADDR             0x78
#define CH_LINKADDR_EN          BIT(0)

#define CH_LINKADDRHI           0x7c
#define CH_ERRINFO              0x90
#define CH_ERRINFO_AXIRDPOISERR BIT(18)
#define CH_ERRINFO_AXIWRRESPERR BIT(17)
#define CH_ERRINFO_AXIRDRESPERR BIT(16)

#define CH_BUILDCFG0            0xf8
#define CH_CFG_INC_WIDTH        GENMASK(29, 26)
#define CH_CFG_DATA_WIDTH       GENMASK(24, 22)
#define CH_CFG_DATA_BUF_SIZE    GENMASK(7, 0)

#define CH_BUILDCFG1            0xfc
#define CH_CFG_HAS_CMDLINK      BIT(8)
#define CH_CFG_HAS_TRIGSEL      BIT(7)
#define CH_CFG_HAS_TRIGIN       BIT(5)
#define CH_CFG_HAS_WRAP         BIT(1)


#define LINK_REGCLEAR           BIT(0)
#define LINK_INTREN             BIT(2)
#define LINK_CTRL               BIT(3)
#define LINK_SRCADDR            BIT(4)
#define LINK_SRCADDRHI          BIT(5)
#define LINK_DESADDR            BIT(6)
#define LINK_DESADDRHI          BIT(7)
#define LINK_XSIZE              BIT(8)
#define LINK_XSIZEHI            BIT(9)
#define LINK_SRCTRANSCFG        BIT(10)
#define LINK_DESTRANSCFG        BIT(11)
#define LINK_XADDRINC           BIT(12)
#define LINK_FILLVAL            BIT(14)
#define LINK_SRCTRIGINCFG       BIT(19)
#define LINK_DESTRIGINCFG       BIT(20)
#define LINK_AUTOCFG            BIT(29)
#define LINK_LINKADDR           BIT(30)
#define LINK_LINKADDRHI         BIT(31)


enum ch_ctrl_donetype {
        CH_CTRL_DONETYPE_NONE = 0,
        CH_CTRL_DONETYPE_CMD = 1,
        CH_CTRL_DONETYPE_CYCLE = 3
};

enum ch_ctrl_xtype {
        CH_CTRL_XTYPE_DISABLE = 0,
        CH_CTRL_XTYPE_CONTINUE = 1,
        CH_CTRL_XTYPE_WRAP = 2,
        CH_CTRL_XTYPE_FILL = 3
};

enum ch_cfg_shareattr {
        SHAREATTR_NSH = 0,
        SHAREATTR_OSH = 2,
        SHAREATTR_ISH = 3
};

enum ch_cfg_memattr {
        MEMATTR_DEVICE = 0x00,
        MEMATTR_NC = 0x44,
        MEMATTR_WB = 0xff
};

struct d350_desc {
        struct virt_dma_desc vd;
        u32 command[16];
        u16 xsize;
        u16 xsizehi;
        u8 tsz;
};

struct d350_chan {
        struct virt_dma_chan vc;
        struct d350_desc *desc;
        void __iomem *base;
        int irq;
        enum dma_status status;
        dma_cookie_t cookie;
        u32 residue;
        u8 tsz;
        bool has_trig;
        bool has_wrap;
        bool coherent;
};

struct d350 {
        struct dma_device dma;
        int nchan;
        int nreq;
        struct d350_chan channels[] __counted_by(nchan);
};

static inline struct d350_chan *to_d350_chan(struct dma_chan *chan)
{
        return container_of(chan, struct d350_chan, vc.chan);
}

static inline struct d350_desc *to_d350_desc(struct virt_dma_desc *vd)
{
        return container_of(vd, struct d350_desc, vd);
}

static void d350_desc_free(struct virt_dma_desc *vd)
{
        kfree(to_d350_desc(vd));
}

static struct dma_async_tx_descriptor *d350_prep_memcpy(struct dma_chan *chan,
                dma_addr_t dest, dma_addr_t src, size_t len, unsigned long flags)
{
        struct d350_chan *dch = to_d350_chan(chan);
        struct d350_desc *desc;
        u32 *cmd;

        desc = kzalloc_obj(*desc, GFP_NOWAIT);
        if (!desc)
                return NULL;

        desc->tsz = __ffs(len | dest | src | (1 << dch->tsz));
        desc->xsize = lower_16_bits(len >> desc->tsz);
        desc->xsizehi = upper_16_bits(len >> desc->tsz);

        cmd = desc->command;
        cmd[0] = LINK_CTRL | LINK_SRCADDR | LINK_SRCADDRHI | LINK_DESADDR |
                 LINK_DESADDRHI | LINK_XSIZE | LINK_XSIZEHI | LINK_SRCTRANSCFG |
                 LINK_DESTRANSCFG | LINK_XADDRINC | LINK_LINKADDR;

        cmd[1] = FIELD_PREP(CH_CTRL_TRANSIZE, desc->tsz) |
                 FIELD_PREP(CH_CTRL_XTYPE, CH_CTRL_XTYPE_CONTINUE) |
                 FIELD_PREP(CH_CTRL_DONETYPE, CH_CTRL_DONETYPE_CMD);

        cmd[2] = lower_32_bits(src);
        cmd[3] = upper_32_bits(src);
        cmd[4] = lower_32_bits(dest);
        cmd[5] = upper_32_bits(dest);
        cmd[6] = FIELD_PREP(CH_XY_SRC, desc->xsize) | FIELD_PREP(CH_XY_DES, desc->xsize);
        cmd[7] = FIELD_PREP(CH_XY_SRC, desc->xsizehi) | FIELD_PREP(CH_XY_DES, desc->xsizehi);
        cmd[8] = dch->coherent ? TRANSCFG_WB : TRANSCFG_NC;
        cmd[9] = dch->coherent ? TRANSCFG_WB : TRANSCFG_NC;
        cmd[10] = FIELD_PREP(CH_XY_SRC, 1) | FIELD_PREP(CH_XY_DES, 1);
        cmd[11] = 0;

        return vchan_tx_prep(&dch->vc, &desc->vd, flags);
}

static struct dma_async_tx_descriptor *d350_prep_memset(struct dma_chan *chan,
                dma_addr_t dest, int value, size_t len, unsigned long flags)
{
        struct d350_chan *dch = to_d350_chan(chan);
        struct d350_desc *desc;
        u32 *cmd;

        desc = kzalloc_obj(*desc, GFP_NOWAIT);
        if (!desc)
                return NULL;

        desc->tsz = __ffs(len | dest | (1 << dch->tsz));
        desc->xsize = lower_16_bits(len >> desc->tsz);
        desc->xsizehi = upper_16_bits(len >> desc->tsz);

        cmd = desc->command;
        cmd[0] = LINK_CTRL | LINK_DESADDR | LINK_DESADDRHI |
                 LINK_XSIZE | LINK_XSIZEHI | LINK_DESTRANSCFG |
                 LINK_XADDRINC | LINK_FILLVAL | LINK_LINKADDR;

        cmd[1] = FIELD_PREP(CH_CTRL_TRANSIZE, desc->tsz) |
                 FIELD_PREP(CH_CTRL_XTYPE, CH_CTRL_XTYPE_FILL) |
                 FIELD_PREP(CH_CTRL_DONETYPE, CH_CTRL_DONETYPE_CMD);

        cmd[2] = lower_32_bits(dest);
        cmd[3] = upper_32_bits(dest);
        cmd[4] = FIELD_PREP(CH_XY_DES, desc->xsize);
        cmd[5] = FIELD_PREP(CH_XY_DES, desc->xsizehi);
        cmd[6] = dch->coherent ? TRANSCFG_WB : TRANSCFG_NC;
        cmd[7] = FIELD_PREP(CH_XY_DES, 1);
        cmd[8] = (u8)value * 0x01010101;
        cmd[9] = 0;

        return vchan_tx_prep(&dch->vc, &desc->vd, flags);
}

static int d350_pause(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&dch->vc.lock, flags);
        if (dch->status == DMA_IN_PROGRESS) {
                writel_relaxed(CH_CMD_PAUSE, dch->base + CH_CMD);
                dch->status = DMA_PAUSED;
        }
        spin_unlock_irqrestore(&dch->vc.lock, flags);

        return 0;
}

static int d350_resume(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&dch->vc.lock, flags);
        if (dch->status == DMA_PAUSED) {
                writel_relaxed(CH_CMD_RESUME, dch->base + CH_CMD);
                dch->status = DMA_IN_PROGRESS;
        }
        spin_unlock_irqrestore(&dch->vc.lock, flags);

        return 0;
}

static u32 d350_get_residue(struct d350_chan *dch)
{
        u32 res, xsize, xsizehi, hi_new;
        int retries = 3; /* 1st time unlucky, 2nd improbable, 3rd just broken */

        hi_new = readl_relaxed(dch->base + CH_XSIZEHI);
        do {
                xsizehi = hi_new;
                xsize = readl_relaxed(dch->base + CH_XSIZE);
                hi_new = readl_relaxed(dch->base + CH_XSIZEHI);
        } while (xsizehi != hi_new && --retries);

        res = FIELD_GET(CH_XY_DES, xsize);
        res |= FIELD_GET(CH_XY_DES, xsizehi) << 16;

        return res << dch->desc->tsz;
}

static int d350_terminate_all(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);
        unsigned long flags;
        LIST_HEAD(list);

        spin_lock_irqsave(&dch->vc.lock, flags);
        writel_relaxed(CH_CMD_STOP, dch->base + CH_CMD);
        if (dch->desc) {
                if (dch->status != DMA_ERROR)
                        vchan_terminate_vdesc(&dch->desc->vd);
                dch->desc = NULL;
                dch->status = DMA_COMPLETE;
        }
        vchan_get_all_descriptors(&dch->vc, &list);
        list_splice_tail(&list, &dch->vc.desc_terminated);
        spin_unlock_irqrestore(&dch->vc.lock, flags);

        return 0;
}

static void d350_synchronize(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);

        vchan_synchronize(&dch->vc);
}

static u32 d350_desc_bytes(struct d350_desc *desc)
{
        return ((u32)desc->xsizehi << 16 | desc->xsize) << desc->tsz;
}

static enum dma_status d350_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                                      struct dma_tx_state *state)
{
        struct d350_chan *dch = to_d350_chan(chan);
        struct virt_dma_desc *vd;
        enum dma_status status;
        unsigned long flags;
        u32 residue = 0;

        status = dma_cookie_status(chan, cookie, state);

        spin_lock_irqsave(&dch->vc.lock, flags);
        if (cookie == dch->cookie) {
                status = dch->status;
                if (status == DMA_IN_PROGRESS || status == DMA_PAUSED)
                        dch->residue = d350_get_residue(dch);
                residue = dch->residue;
        } else if ((vd = vchan_find_desc(&dch->vc, cookie))) {
                residue = d350_desc_bytes(to_d350_desc(vd));
        } else if (status == DMA_IN_PROGRESS) {
                /* Somebody else terminated it? */
                status = DMA_ERROR;
        }
        spin_unlock_irqrestore(&dch->vc.lock, flags);

        dma_set_residue(state, residue);
        return status;
}

static void d350_start_next(struct d350_chan *dch)
{
        u32 hdr, *reg;

        dch->desc = to_d350_desc(vchan_next_desc(&dch->vc));
        if (!dch->desc)
                return;

        list_del(&dch->desc->vd.node);
        dch->status = DMA_IN_PROGRESS;
        dch->cookie = dch->desc->vd.tx.cookie;
        dch->residue = d350_desc_bytes(dch->desc);

        hdr = dch->desc->command[0];
        reg = &dch->desc->command[1];

        if (hdr & LINK_INTREN)
                writel_relaxed(*reg++, dch->base + CH_INTREN);
        if (hdr & LINK_CTRL)
                writel_relaxed(*reg++, dch->base + CH_CTRL);
        if (hdr & LINK_SRCADDR)
                writel_relaxed(*reg++, dch->base + CH_SRCADDR);
        if (hdr & LINK_SRCADDRHI)
                writel_relaxed(*reg++, dch->base + CH_SRCADDRHI);
        if (hdr & LINK_DESADDR)
                writel_relaxed(*reg++, dch->base + CH_DESADDR);
        if (hdr & LINK_DESADDRHI)
                writel_relaxed(*reg++, dch->base + CH_DESADDRHI);
        if (hdr & LINK_XSIZE)
                writel_relaxed(*reg++, dch->base + CH_XSIZE);
        if (hdr & LINK_XSIZEHI)
                writel_relaxed(*reg++, dch->base + CH_XSIZEHI);
        if (hdr & LINK_SRCTRANSCFG)
                writel_relaxed(*reg++, dch->base + CH_SRCTRANSCFG);
        if (hdr & LINK_DESTRANSCFG)
                writel_relaxed(*reg++, dch->base + CH_DESTRANSCFG);
        if (hdr & LINK_XADDRINC)
                writel_relaxed(*reg++, dch->base + CH_XADDRINC);
        if (hdr & LINK_FILLVAL)
                writel_relaxed(*reg++, dch->base + CH_FILLVAL);
        if (hdr & LINK_SRCTRIGINCFG)
                writel_relaxed(*reg++, dch->base + CH_SRCTRIGINCFG);
        if (hdr & LINK_DESTRIGINCFG)
                writel_relaxed(*reg++, dch->base + CH_DESTRIGINCFG);
        if (hdr & LINK_AUTOCFG)
                writel_relaxed(*reg++, dch->base + CH_AUTOCFG);
        if (hdr & LINK_LINKADDR)
                writel_relaxed(*reg++, dch->base + CH_LINKADDR);
        if (hdr & LINK_LINKADDRHI)
                writel_relaxed(*reg++, dch->base + CH_LINKADDRHI);

        writel(CH_CMD_ENABLE, dch->base + CH_CMD);
}

static void d350_issue_pending(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&dch->vc.lock, flags);
        if (vchan_issue_pending(&dch->vc) && !dch->desc)
                d350_start_next(dch);
        spin_unlock_irqrestore(&dch->vc.lock, flags);
}

static irqreturn_t d350_irq(int irq, void *data)
{
        struct d350_chan *dch = data;
        struct device *dev = dch->vc.chan.device->dev;
        struct virt_dma_desc *vd = &dch->desc->vd;
        u32 ch_status;

        ch_status = readl(dch->base + CH_STATUS);
        if (!ch_status)
                return IRQ_NONE;

        if (ch_status & CH_STAT_INTR_ERR) {
                u32 errinfo = readl_relaxed(dch->base + CH_ERRINFO);

                if (errinfo & (CH_ERRINFO_AXIRDPOISERR | CH_ERRINFO_AXIRDRESPERR))
                        vd->tx_result.result = DMA_TRANS_READ_FAILED;
                else if (errinfo & CH_ERRINFO_AXIWRRESPERR)
                        vd->tx_result.result = DMA_TRANS_WRITE_FAILED;
                else
                        vd->tx_result.result = DMA_TRANS_ABORTED;

                vd->tx_result.residue = d350_get_residue(dch);
        } else if (!(ch_status & CH_STAT_INTR_DONE)) {
                dev_warn(dev, "Unexpected IRQ source? 0x%08x\n", ch_status);
        }
        writel_relaxed(ch_status, dch->base + CH_STATUS);

        spin_lock(&dch->vc.lock);
        vchan_cookie_complete(vd);
        if (ch_status & CH_STAT_INTR_DONE) {
                dch->status = DMA_COMPLETE;
                dch->residue = 0;
                d350_start_next(dch);
        } else {
                dch->status = DMA_ERROR;
                dch->residue = vd->tx_result.residue;
        }
        spin_unlock(&dch->vc.lock);

        return IRQ_HANDLED;
}

static int d350_alloc_chan_resources(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);
        int ret = request_irq(dch->irq, d350_irq, IRQF_SHARED,
                              dev_name(&dch->vc.chan.dev->device), dch);
        if (!ret)
                writel_relaxed(CH_INTREN_DONE | CH_INTREN_ERR, dch->base + CH_INTREN);

        return ret;
}

static void d350_free_chan_resources(struct dma_chan *chan)
{
        struct d350_chan *dch = to_d350_chan(chan);

        writel_relaxed(0, dch->base + CH_INTREN);
        free_irq(dch->irq, dch);
        vchan_free_chan_resources(&dch->vc);
}

static int d350_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct d350 *dmac;
        void __iomem *base;
        u32 reg;
        int ret, nchan, dw, aw, r, p;
        bool coherent, memset;

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

        reg = readl_relaxed(base + DMAINFO + IIDR);
        r = FIELD_GET(IIDR_VARIANT, reg);
        p = FIELD_GET(IIDR_REVISION, reg);
        if (FIELD_GET(IIDR_IMPLEMENTER, reg) != IMPLEMENTER_ARM ||
            FIELD_GET(IIDR_PRODUCTID, reg) != PRODUCTID_DMA350)
                return dev_err_probe(dev, -ENODEV, "Not a DMA-350!");

        reg = readl_relaxed(base + DMAINFO + DMA_BUILDCFG0);
        nchan = FIELD_GET(DMA_CFG_NUM_CHANNELS, reg) + 1;
        dw = 1 << FIELD_GET(DMA_CFG_DATA_WIDTH, reg);
        aw = FIELD_GET(DMA_CFG_ADDR_WIDTH, reg) + 1;

        dma_set_mask_and_coherent(dev, DMA_BIT_MASK(aw));
        coherent = device_get_dma_attr(dev) == DEV_DMA_COHERENT;

        dmac = devm_kzalloc(dev, struct_size(dmac, channels, nchan), GFP_KERNEL);
        if (!dmac)
                return -ENOMEM;

        dmac->nchan = nchan;

        reg = readl_relaxed(base + DMAINFO + DMA_BUILDCFG1);
        dmac->nreq = FIELD_GET(DMA_CFG_NUM_TRIGGER_IN, reg);

        dev_dbg(dev, "DMA-350 r%dp%d with %d channels, %d requests\n", r, p, dmac->nchan, dmac->nreq);

        dmac->dma.dev = dev;
        for (int i = min(dw, 16); i > 0; i /= 2) {
                dmac->dma.src_addr_widths |= BIT(i);
                dmac->dma.dst_addr_widths |= BIT(i);
        }
        dmac->dma.directions = BIT(DMA_MEM_TO_MEM);
        dmac->dma.descriptor_reuse = true;
        dmac->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
        dmac->dma.device_alloc_chan_resources = d350_alloc_chan_resources;
        dmac->dma.device_free_chan_resources = d350_free_chan_resources;
        dma_cap_set(DMA_MEMCPY, dmac->dma.cap_mask);
        dmac->dma.device_prep_dma_memcpy = d350_prep_memcpy;
        dmac->dma.device_pause = d350_pause;
        dmac->dma.device_resume = d350_resume;
        dmac->dma.device_terminate_all = d350_terminate_all;
        dmac->dma.device_synchronize = d350_synchronize;
        dmac->dma.device_tx_status = d350_tx_status;
        dmac->dma.device_issue_pending = d350_issue_pending;
        INIT_LIST_HEAD(&dmac->dma.channels);

        /* Would be nice to have per-channel caps for this... */
        memset = true;
        for (int i = 0; i < nchan; i++) {
                struct d350_chan *dch = &dmac->channels[i];

                dch->base = base + DMACH(i);
                writel_relaxed(CH_CMD_CLEAR, dch->base + CH_CMD);

                reg = readl_relaxed(dch->base + CH_BUILDCFG1);
                if (!(FIELD_GET(CH_CFG_HAS_CMDLINK, reg))) {
                        dev_warn(dev, "No command link support on channel %d\n", i);
                        continue;
                }
                dch->irq = platform_get_irq(pdev, i);
                if (dch->irq < 0)
                        return dev_err_probe(dev, dch->irq,
                                             "Failed to get IRQ for channel %d\n", i);

                dch->has_wrap = FIELD_GET(CH_CFG_HAS_WRAP, reg);
                dch->has_trig = FIELD_GET(CH_CFG_HAS_TRIGIN, reg) &
                                FIELD_GET(CH_CFG_HAS_TRIGSEL, reg);

                /* Fill is a special case of Wrap */
                memset &= dch->has_wrap;

                reg = readl_relaxed(dch->base + CH_BUILDCFG0);
                dch->tsz = FIELD_GET(CH_CFG_DATA_WIDTH, reg);

                reg = FIELD_PREP(CH_LINK_SHAREATTR, coherent ? SHAREATTR_ISH : SHAREATTR_OSH);
                reg |= FIELD_PREP(CH_LINK_MEMATTR, coherent ? MEMATTR_WB : MEMATTR_NC);
                writel_relaxed(reg, dch->base + CH_LINKATTR);

                dch->vc.desc_free = d350_desc_free;
                vchan_init(&dch->vc, &dmac->dma);
        }

        if (memset) {
                dma_cap_set(DMA_MEMSET, dmac->dma.cap_mask);
                dmac->dma.device_prep_dma_memset = d350_prep_memset;
        }

        platform_set_drvdata(pdev, dmac);

        ret = dma_async_device_register(&dmac->dma);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to register DMA device\n");

        return 0;
}

static void d350_remove(struct platform_device *pdev)
{
        struct d350 *dmac = platform_get_drvdata(pdev);

        dma_async_device_unregister(&dmac->dma);
}

static const struct of_device_id d350_of_match[] __maybe_unused = {
        { .compatible = "arm,dma-350" },
        {}
};
MODULE_DEVICE_TABLE(of, d350_of_match);

static struct platform_driver d350_driver = {
        .driver = {
                .name = "arm-dma350",
                .of_match_table = of_match_ptr(d350_of_match),
        },
        .probe = d350_probe,
        .remove = d350_remove,
};
module_platform_driver(d350_driver);

MODULE_AUTHOR("Robin Murphy <robin.murphy@arm.com>");
MODULE_DESCRIPTION("Arm DMA-350 driver");
MODULE_LICENSE("GPL v2");