Archipelago » qemu

/*

 * Syborg serial port

 *

 * Copyright (c) 2008 CodeSourcery

 *

 * 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-char.h"

#include "syborg.h"

//#define DEBUG_SYBORG_SERIAL

#ifdef DEBUG_SYBORG_SERIAL

#define DPRINTF(fmt, ...) \

do { printf("syborg_serial: " fmt , ##args); } while (0)

#define BADF(fmt, ...) \

do { fprintf(stderr, "syborg_serial: error: " fmt , ## __VA_ARGS__); \

    exit(1);} while (0)

#else

#define DPRINTF(fmt, ...) do {} while(0)

#define BADF(fmt, ...) \

do { fprintf(stderr, "syborg_serial: error: " fmt , ## __VA_ARGS__);} while (0)

#endif

enum {

    SERIAL_ID           = 0,

    SERIAL_DATA         = 1,

    SERIAL_FIFO_COUNT   = 2,

    SERIAL_INT_ENABLE   = 3,

    SERIAL_DMA_TX_ADDR  = 4,

    SERIAL_DMA_TX_COUNT = 5, /* triggers dma */

    SERIAL_DMA_RX_ADDR  = 6,

    SERIAL_DMA_RX_COUNT = 7, /* triggers dma */

    SERIAL_FIFO_SIZE    = 8

};

#define SERIAL_INT_FIFO   (1u << 0)

#define SERIAL_INT_DMA_TX (1u << 1)

#define SERIAL_INT_DMA_RX (1u << 2)

typedef struct {

    SysBusDevice busdev;

    uint32_t int_enable;

    uint32_t fifo_size;

    uint32_t *read_fifo;

    int read_pos;

    int read_count;

    CharDriverState *chr;

    qemu_irq irq;

    uint32_t dma_tx_ptr;

    uint32_t dma_rx_ptr;

    uint32_t dma_rx_size;

} SyborgSerialState;

static void syborg_serial_update(SyborgSerialState *s)

{

    int level;

    level = 0;

    if ((s->int_enable & SERIAL_INT_FIFO) && s->read_count)

        level = 1;

    if (s->int_enable & SERIAL_INT_DMA_TX)

        level = 1;

    if ((s->int_enable & SERIAL_INT_DMA_RX) && s->dma_rx_size == 0)

        level = 1;

    qemu_set_irq(s->irq, level);

}

static uint32_t fifo_pop(SyborgSerialState *s)

{

    const uint32_t c = s->read_fifo[s->read_pos];

    s->read_count--;

    s->read_pos++;

    if (s->read_pos == s->fifo_size)

        s->read_pos = 0;

    DPRINTF("FIFO pop %x (%d)\n", c, s->read_count);

    return c;

}

static void fifo_push(SyborgSerialState *s, uint32_t new_value)

{

    int slot;

    DPRINTF("FIFO push %x (%d)\n", new_value, s->read_count);

    slot = s->read_pos + s->read_count;

    if (slot >= s->fifo_size)

          slot -= s->fifo_size;

    s->read_fifo[slot] = new_value;

    s->read_count++;

}

static void do_dma_tx(SyborgSerialState *s, uint32_t count)

{

    unsigned char ch;

    if (count == 0)

        return;

    if (s->chr != NULL) {

        /* optimize later. Now, 1 byte per iteration */

        while (count--) {

            cpu_physical_memory_read(s->dma_tx_ptr, &ch, 1);

            qemu_chr_write(s->chr, &ch, 1);

            s->dma_tx_ptr++;

        }

    } else {

        s->dma_tx_ptr += count;

    }

    /* QEMU char backends do not have a nonblocking mode, so we transmit all

       the data imediately and the interrupt status will be unchanged.  */

}

/* Initiate RX DMA, and transfer data from the FIFO.  */

static void dma_rx_start(SyborgSerialState *s, uint32_t len)

{

    uint32_t dest;

    unsigned char ch;

    dest = s->dma_rx_ptr;

    if (s->read_count < len) {

        s->dma_rx_size = len - s->read_count;

        len = s->read_count;

    } else {

        s->dma_rx_size = 0;

    }

    while (len--) {

        ch = fifo_pop(s);

        cpu_physical_memory_write(dest, &ch, 1);

        dest++;

    }

    s->dma_rx_ptr = dest;

    syborg_serial_update(s);

}

static uint32_t syborg_serial_read(void *opaque, target_phys_addr_t offset)

{

    SyborgSerialState *s = (SyborgSerialState *)opaque;

    uint32_t c;

    offset &= 0xfff;

    DPRINTF("read 0x%x\n", (int)offset);

    switch(offset >> 2) {

    case SERIAL_ID:

        return SYBORG_ID_SERIAL;

    case SERIAL_DATA:

        if (s->read_count > 0)

            c = fifo_pop(s);

        else

            c = -1;

        syborg_serial_update(s);

        return c;

    case SERIAL_FIFO_COUNT:

        return s->read_count;

    case SERIAL_INT_ENABLE:

        return s->int_enable;

    case SERIAL_DMA_TX_ADDR:

        return s->dma_tx_ptr;

    case SERIAL_DMA_TX_COUNT:

        return 0;

    case SERIAL_DMA_RX_ADDR:

        return s->dma_rx_ptr;

    case SERIAL_DMA_RX_COUNT:

        return s->dma_rx_size;

    case SERIAL_FIFO_SIZE:

        return s->fifo_size;

    default:

        cpu_abort(cpu_single_env, "syborg_serial_read: Bad offset %x\n",

                  (int)offset);

        return 0;

    }

}

static void syborg_serial_write(void *opaque, target_phys_addr_t offset,

                                uint32_t value)

{

    SyborgSerialState *s = (SyborgSerialState *)opaque;

    unsigned char ch;

    offset &= 0xfff;

    DPRINTF("Write 0x%x=0x%x\n", (int)offset, value);

    switch (offset >> 2) {

    case SERIAL_DATA:

        ch = value;

        if (s->chr)

            qemu_chr_write(s->chr, &ch, 1);

        break;

    case SERIAL_INT_ENABLE:

        s->int_enable = value;

        syborg_serial_update(s);

        break;

    case SERIAL_DMA_TX_ADDR:

        s->dma_tx_ptr = value;

        break;

    case SERIAL_DMA_TX_COUNT:

        do_dma_tx(s, value);

        break;

    case SERIAL_DMA_RX_ADDR:

        /* For safety, writes to this register cancel any pending DMA.  */

        s->dma_rx_size = 0;

        s->dma_rx_ptr = value;

        break;

    case SERIAL_DMA_RX_COUNT:

        dma_rx_start(s, value);

        break;

    default:

        cpu_abort(cpu_single_env, "syborg_serial_write: Bad offset %x\n",

                  (int)offset);

        break;

    }

}

static int syborg_serial_can_receive(void *opaque)

{

    SyborgSerialState *s = (SyborgSerialState *)opaque;

    if (s->dma_rx_size)

        return s->dma_rx_size;

    return s->fifo_size - s->read_count;

}

static void syborg_serial_receive(void *opaque, const uint8_t *buf, int size)

{

    SyborgSerialState *s = (SyborgSerialState *)opaque;

    if (s->dma_rx_size) {

        /* Place it in the DMA buffer.  */

        cpu_physical_memory_write(s->dma_rx_ptr, buf, size);

        s->dma_rx_size -= size;

        s->dma_rx_ptr += size;

    } else {

        while (size--)

            fifo_push(s, *buf);

    }

    syborg_serial_update(s);

}

static void syborg_serial_event(void *opaque, int event)

{

    /* TODO: Report BREAK events?  */

}

static CPUReadMemoryFunc *syborg_serial_readfn[] = {

     syborg_serial_read,

     syborg_serial_read,

     syborg_serial_read

};

static CPUWriteMemoryFunc *syborg_serial_writefn[] = {

     syborg_serial_write,

     syborg_serial_write,

     syborg_serial_write

};

static void syborg_serial_save(QEMUFile *f, void *opaque)

{

    SyborgSerialState *s = opaque;

    int i;

    qemu_put_be32(f, s->fifo_size);

    qemu_put_be32(f, s->int_enable);

    qemu_put_be32(f, s->read_pos);

    qemu_put_be32(f, s->read_count);

    qemu_put_be32(f, s->dma_tx_ptr);

    qemu_put_be32(f, s->dma_rx_ptr);

    qemu_put_be32(f, s->dma_rx_size);

    for (i = 0; i < s->fifo_size; i++) {

        qemu_put_be32(f, s->read_fifo[i]);

    }

}

static int syborg_serial_load(QEMUFile *f, void *opaque, int version_id)

{

    SyborgSerialState *s = opaque;

    int i;

    if (version_id != 1)

        return -EINVAL;

    i = qemu_get_be32(f);

    if (s->fifo_size != i)

        return -EINVAL;

    s->int_enable = qemu_get_be32(f);

    s->read_pos = qemu_get_be32(f);

    s->read_count = qemu_get_be32(f);

    s->dma_tx_ptr = qemu_get_be32(f);

    s->dma_rx_ptr = qemu_get_be32(f);

    s->dma_rx_size = qemu_get_be32(f);

    for (i = 0; i < s->fifo_size; i++) {

        s->read_fifo[i] = qemu_get_be32(f);

    }

    return 0;

}

static void syborg_serial_init(SysBusDevice *dev)

{

    SyborgSerialState *s = FROM_SYSBUS(SyborgSerialState, dev);

    int iomemtype;

    sysbus_init_irq(dev, &s->irq);

    iomemtype = cpu_register_io_memory(syborg_serial_readfn,

                                       syborg_serial_writefn, s);

    sysbus_init_mmio(dev, 0x1000, iomemtype);

    s->chr = qdev_init_chardev(&dev->qdev);

    if (s->chr) {

        qemu_chr_add_handlers(s->chr, syborg_serial_can_receive,

                              syborg_serial_receive, syborg_serial_event, s);

    }

    if (s->fifo_size <= 0) {

        fprintf(stderr, "syborg_serial: fifo too small\n");

        s->fifo_size = 16;

    }

    s->read_fifo = qemu_mallocz(s->fifo_size * sizeof(s->read_fifo[0]));

    register_savevm("syborg_serial", -1, 1,

                    syborg_serial_save, syborg_serial_load, s);

}

static SysBusDeviceInfo syborg_serial_info = {

    .init = syborg_serial_init,

    .qdev.name  = "syborg,serial",

    .qdev.size  = sizeof(SyborgSerialState),

    .qdev.props = (Property[]) {

        {

            .name   = "fifo-size",

            .info   = &qdev_prop_uint32,

            .offset = offsetof(SyborgSerialState, fifo_size),

            .defval = (uint32_t[]) { 16 },

        },

        {/* end of list */}

    }

};

static void syborg_serial_register_devices(void)

{

    sysbus_register_withprop(&syborg_serial_info);

}

device_init(syborg_serial_register_devices)