hw/xilinx_axidma.c - qemu - Git at Google

 /*
  * 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 "sysbus.h"
 #include "qemu/timer.h"
 #include "ptimer.h"
 #include "qemu/log.h"
 #include "qdev-addr.h"

 #include "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)
	/*
	* 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 "sysbus.h"
	#include "qemu/timer.h"
	#include "ptimer.h"
	#include "qemu/log.h"
	#include "qdev-addr.h"

	#include "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)