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/*

 * QEMU model of Xilinx AXI-DMA block.

 *

 * Copyright (c) 2011 Edgar E. Iglesias.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "hw/sysbus.h"

#include "qemu/timer.h"

#include "hw/ptimer.h"

#include "qemu/log.h"

#include "hw/qdev-addr.h"

#include "hw/stream.h"

#define D(x)

#define R_DMACR             (0x00 / 4)

#define R_DMASR             (0x04 / 4)

#define R_CURDESC           (0x08 / 4)

#define R_TAILDESC          (0x10 / 4)

#define R_MAX               (0x30 / 4)

enum {

    DMACR_RUNSTOP = 1,

    DMACR_TAILPTR_MODE = 2,

    DMACR_RESET = 4

};

enum {

    DMASR_HALTED = 1,

    DMASR_IDLE  = 2,

    DMASR_IOC_IRQ  = 1 << 12,

    DMASR_DLY_IRQ  = 1 << 13,

    DMASR_IRQ_MASK = 7 << 12

};

struct SDesc {

    uint64_t nxtdesc;

    uint64_t buffer_address;

    uint64_t reserved;

    uint32_t control;

    uint32_t status;

    uint32_t app[6];

};

enum {

    SDESC_CTRL_EOF = (1 << 26),

    SDESC_CTRL_SOF = (1 << 27),

    SDESC_CTRL_LEN_MASK = (1 << 23) - 1

};

enum {

    SDESC_STATUS_EOF = (1 << 26),

    SDESC_STATUS_SOF_BIT = 27,

    SDESC_STATUS_SOF = (1 << SDESC_STATUS_SOF_BIT),

    SDESC_STATUS_COMPLETE = (1 << 31)

};

struct Stream {

    QEMUBH *bh;

    ptimer_state *ptimer;

    qemu_irq irq;

    int nr;

    struct SDesc desc;

    int pos;

    unsigned int complete_cnt;

    uint32_t regs[R_MAX];

};

struct XilinxAXIDMA {

    SysBusDevice busdev;

    MemoryRegion iomem;

    uint32_t freqhz;

    StreamSlave *tx_dev;

    struct Stream streams[2];

};

/*

 * Helper calls to extract info from desriptors and other trivial

 * state from regs.

 */

static inline int stream_desc_sof(struct SDesc *d)

{

    return d->control & SDESC_CTRL_SOF;

}

static inline int stream_desc_eof(struct SDesc *d)

{

    return d->control & SDESC_CTRL_EOF;

}

static inline int stream_resetting(struct Stream *s)

{

    return !!(s->regs[R_DMACR] & DMACR_RESET);

}

static inline int stream_running(struct Stream *s)

{

    return s->regs[R_DMACR] & DMACR_RUNSTOP;

}

static inline int stream_halted(struct Stream *s)

{

    return s->regs[R_DMASR] & DMASR_HALTED;

}

static inline int stream_idle(struct Stream *s)

{

    return !!(s->regs[R_DMASR] & DMASR_IDLE);

}

static void stream_reset(struct Stream *s)

{

    s->regs[R_DMASR] = DMASR_HALTED;  /* starts up halted.  */

    s->regs[R_DMACR] = 1 << 16; /* Starts with one in compl threshold.  */

}

/* Map an offset addr into a channel index.  */

static inline int streamid_from_addr(hwaddr addr)

{

    int sid;

    sid = addr / (0x30);

    sid &= 1;

    return sid;

}

#ifdef DEBUG_ENET

static void stream_desc_show(struct SDesc *d)

{

    qemu_log("buffer_addr  = " PRIx64 "\n", d->buffer_address);

    qemu_log("nxtdesc      = " PRIx64 "\n", d->nxtdesc);

    qemu_log("control      = %x\n", d->control);

    qemu_log("status       = %x\n", d->status);

}

#endif

static void stream_desc_load(struct Stream *s, hwaddr addr)

{

    struct SDesc *d = &s->desc;

    int i;

    cpu_physical_memory_read(addr, (void *) d, sizeof *d);

    /* Convert from LE into host endianness.  */

    d->buffer_address = le64_to_cpu(d->buffer_address);

    d->nxtdesc = le64_to_cpu(d->nxtdesc);

    d->control = le32_to_cpu(d->control);

    d->status = le32_to_cpu(d->status);

    for (i = 0; i < ARRAY_SIZE(d->app); i++) {

        d->app[i] = le32_to_cpu(d->app[i]);

    }

}

static void stream_desc_store(struct Stream *s, hwaddr addr)

{

    struct SDesc *d = &s->desc;

    int i;

    /* Convert from host endianness into LE.  */

    d->buffer_address = cpu_to_le64(d->buffer_address);

    d->nxtdesc = cpu_to_le64(d->nxtdesc);

    d->control = cpu_to_le32(d->control);

    d->status = cpu_to_le32(d->status);

    for (i = 0; i < ARRAY_SIZE(d->app); i++) {

        d->app[i] = cpu_to_le32(d->app[i]);

    }

    cpu_physical_memory_write(addr, (void *) d, sizeof *d);

}

static void stream_update_irq(struct Stream *s)

{

    unsigned int pending, mask, irq;

    pending = s->regs[R_DMASR] & DMASR_IRQ_MASK;

    mask = s->regs[R_DMACR] & DMASR_IRQ_MASK;

    irq = pending & mask;

    qemu_set_irq(s->irq, !!irq);

}

static void stream_reload_complete_cnt(struct Stream *s)

{

    unsigned int comp_th;

    comp_th = (s->regs[R_DMACR] >> 16) & 0xff;

    s->complete_cnt = comp_th;

}

static void timer_hit(void *opaque)

{

    struct Stream *s = opaque;

    stream_reload_complete_cnt(s);

    s->regs[R_DMASR] |= DMASR_DLY_IRQ;

    stream_update_irq(s);

}

static void stream_complete(struct Stream *s)

{

    unsigned int comp_delay;

    /* Start the delayed timer.  */

    comp_delay = s->regs[R_DMACR] >> 24;

    if (comp_delay) {

        ptimer_stop(s->ptimer);

        ptimer_set_count(s->ptimer, comp_delay);

        ptimer_run(s->ptimer, 1);

    }

    s->complete_cnt--;

    if (s->complete_cnt == 0) {

        /* Raise the IOC irq.  */

        s->regs[R_DMASR] |= DMASR_IOC_IRQ;

        stream_reload_complete_cnt(s);

    }

}

static void stream_process_mem2s(struct Stream *s,

                                 StreamSlave *tx_dev)

{

    uint32_t prev_d;

    unsigned char txbuf[16 * 1024];

    unsigned int txlen;

    uint32_t app[6];

    if (!stream_running(s) || stream_idle(s)) {

        return;

    }

    while (1) {

        stream_desc_load(s, s->regs[R_CURDESC]);

        if (s->desc.status & SDESC_STATUS_COMPLETE) {

            s->regs[R_DMASR] |= DMASR_IDLE;

            break;

        }

        if (stream_desc_sof(&s->desc)) {

            s->pos = 0;

            memcpy(app, s->desc.app, sizeof app);

        }

        txlen = s->desc.control & SDESC_CTRL_LEN_MASK;

        if ((txlen + s->pos) > sizeof txbuf) {

            hw_error("%s: too small internal txbuf! %d\n", __func__,

                     txlen + s->pos);

        }

        cpu_physical_memory_read(s->desc.buffer_address,

                                 txbuf + s->pos, txlen);

        s->pos += txlen;

        if (stream_desc_eof(&s->desc)) {

            stream_push(tx_dev, txbuf, s->pos, app);

            s->pos = 0;

            stream_complete(s);

        }

        /* Update the descriptor.  */

        s->desc.status = txlen | SDESC_STATUS_COMPLETE;

        stream_desc_store(s, s->regs[R_CURDESC]);

        /* Advance.  */

        prev_d = s->regs[R_CURDESC];

        s->regs[R_CURDESC] = s->desc.nxtdesc;

        if (prev_d == s->regs[R_TAILDESC]) {

            s->regs[R_DMASR] |= DMASR_IDLE;

            break;

        }

    }

}

static void stream_process_s2mem(struct Stream *s,

                                 unsigned char *buf, size_t len, uint32_t *app)

{

    uint32_t prev_d;

    unsigned int rxlen;

    int pos = 0;

    int sof = 1;

    if (!stream_running(s) || stream_idle(s)) {

        return;

    }

    while (len) {

        stream_desc_load(s, s->regs[R_CURDESC]);

        if (s->desc.status & SDESC_STATUS_COMPLETE) {

            s->regs[R_DMASR] |= DMASR_IDLE;

            break;

        }

        rxlen = s->desc.control & SDESC_CTRL_LEN_MASK;

        if (rxlen > len) {

            /* It fits.  */

            rxlen = len;

        }

        cpu_physical_memory_write(s->desc.buffer_address, buf + pos, rxlen);

        len -= rxlen;

        pos += rxlen;

        /* Update the descriptor.  */

        if (!len) {

            int i;

            stream_complete(s);

            for (i = 0; i < 5; i++) {

                s->desc.app[i] = app[i];

            }

            s->desc.status |= SDESC_STATUS_EOF;

        }

        s->desc.status |= sof << SDESC_STATUS_SOF_BIT;

        s->desc.status |= SDESC_STATUS_COMPLETE;

        stream_desc_store(s, s->regs[R_CURDESC]);

        sof = 0;

        /* Advance.  */

        prev_d = s->regs[R_CURDESC];

        s->regs[R_CURDESC] = s->desc.nxtdesc;

        if (prev_d == s->regs[R_TAILDESC]) {

            s->regs[R_DMASR] |= DMASR_IDLE;

            break;

        }

    }

}

static void

axidma_push(StreamSlave *obj, unsigned char *buf, size_t len, uint32_t *app)

{

    struct XilinxAXIDMA *d = FROM_SYSBUS(typeof(*d), SYS_BUS_DEVICE(obj));

    struct Stream *s = &d->streams[1];

    if (!app) {

        hw_error("No stream app data!\n");

    }

    stream_process_s2mem(s, buf, len, app);

    stream_update_irq(s);

}

static uint64_t axidma_read(void *opaque, hwaddr addr,

                            unsigned size)

{

    struct XilinxAXIDMA *d = opaque;

    struct Stream *s;

    uint32_t r = 0;

    int sid;

    sid = streamid_from_addr(addr);

    s = &d->streams[sid];

    addr = addr % 0x30;

    addr >>= 2;

    switch (addr) {

        case R_DMACR:

            /* Simulate one cycles reset delay.  */

            s->regs[addr] &= ~DMACR_RESET;

            r = s->regs[addr];

            break;

        case R_DMASR:

            s->regs[addr] &= 0xffff;

            s->regs[addr] |= (s->complete_cnt & 0xff) << 16;

            s->regs[addr] |= (ptimer_get_count(s->ptimer) & 0xff) << 24;

            r = s->regs[addr];

            break;

        default:

            r = s->regs[addr];

            D(qemu_log("%s ch=%d addr=" TARGET_FMT_plx " v=%x\n",

                           __func__, sid, addr * 4, r));

            break;

    }

    return r;

}

static void axidma_write(void *opaque, hwaddr addr,

                         uint64_t value, unsigned size)

{

    struct XilinxAXIDMA *d = opaque;

    struct Stream *s;

    int sid;

    sid = streamid_from_addr(addr);

    s = &d->streams[sid];

    addr = addr % 0x30;

    addr >>= 2;

    switch (addr) {

        case R_DMACR:

            /* Tailptr mode is always on.  */

            value |= DMACR_TAILPTR_MODE;

            /* Remember our previous reset state.  */

            value |= (s->regs[addr] & DMACR_RESET);

            s->regs[addr] = value;

            if (value & DMACR_RESET) {

                stream_reset(s);

            }

            if ((value & 1) && !stream_resetting(s)) {

                /* Start processing.  */

                s->regs[R_DMASR] &= ~(DMASR_HALTED | DMASR_IDLE);

            }

            stream_reload_complete_cnt(s);

            break;

        case R_DMASR:

            /* Mask away write to clear irq lines.  */

            value &= ~(value & DMASR_IRQ_MASK);

            s->regs[addr] = value;

            break;

        case R_TAILDESC:

            s->regs[addr] = value;

            s->regs[R_DMASR] &= ~DMASR_IDLE; /* Not idle.  */

            if (!sid) {

                stream_process_mem2s(s, d->tx_dev);

            }

            break;

        default:

            D(qemu_log("%s: ch=%d addr=" TARGET_FMT_plx " v=%x\n",

                  __func__, sid, addr * 4, (unsigned)value));

            s->regs[addr] = value;

            break;

    }

    stream_update_irq(s);

}

static const MemoryRegionOps axidma_ops = {

    .read = axidma_read,

    .write = axidma_write,

    .endianness = DEVICE_NATIVE_ENDIAN,

};

static int xilinx_axidma_init(SysBusDevice *dev)

{

    struct XilinxAXIDMA *s = FROM_SYSBUS(typeof(*s), dev);

    int i;

    sysbus_init_irq(dev, &s->streams[0].irq);

    sysbus_init_irq(dev, &s->streams[1].irq);

    memory_region_init_io(&s->iomem, &axidma_ops, s,

                          "xlnx.axi-dma", R_MAX * 4 * 2);

    sysbus_init_mmio(dev, &s->iomem);

    for (i = 0; i < 2; i++) {

        stream_reset(&s->streams[i]);

        s->streams[i].nr = i;

        s->streams[i].bh = qemu_bh_new(timer_hit, &s->streams[i]);

        s->streams[i].ptimer = ptimer_init(s->streams[i].bh);

        ptimer_set_freq(s->streams[i].ptimer, s->freqhz);

    }

    return 0;

}

static void xilinx_axidma_initfn(Object *obj)

{

    struct XilinxAXIDMA *s = FROM_SYSBUS(typeof(*s), SYS_BUS_DEVICE(obj));

    object_property_add_link(obj, "axistream-connected", TYPE_STREAM_SLAVE,

                             (Object **) &s->tx_dev, NULL);

}

static Property axidma_properties[] = {

    DEFINE_PROP_UINT32("freqhz", struct XilinxAXIDMA, freqhz, 50000000),

    DEFINE_PROP_END_OF_LIST(),

};

static void axidma_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);

    StreamSlaveClass *ssc = STREAM_SLAVE_CLASS(klass);

    k->init = xilinx_axidma_init;

    dc->props = axidma_properties;

    ssc->push = axidma_push;

}

static const TypeInfo axidma_info = {

    .name          = "xlnx.axi-dma",

    .parent        = TYPE_SYS_BUS_DEVICE,

    .instance_size = sizeof(struct XilinxAXIDMA),

    .class_init    = axidma_class_init,

    .instance_init = xilinx_axidma_initfn,

    .interfaces = (InterfaceInfo[]) {

        { TYPE_STREAM_SLAVE },

        { }

    }

};

static void xilinx_axidma_register_types(void)

{

    type_register_static(&axidma_info);

}

type_init(xilinx_axidma_register_types)