Archipelago » qemu

/*

 * QEMU ETRAX System Emulator

 *

 * Copyright (c) 2007 Edgar E. Iglesias, Axis Communications AB.

 *

 * 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"

#define D(x)

#define RW_TR_CTRL     (0x00 / 4)

#define RW_TR_DMA_EN   (0x04 / 4)

#define RW_REC_CTRL    (0x08 / 4)

#define RW_DOUT        (0x1c / 4)

#define RS_STAT_DIN    (0x20 / 4)

#define R_STAT_DIN     (0x24 / 4)

#define RW_INTR_MASK   (0x2c / 4)

#define RW_ACK_INTR    (0x30 / 4)

#define R_INTR         (0x34 / 4)

#define R_MASKED_INTR  (0x38 / 4)

#define R_MAX          (0x3c / 4)

#define STAT_DAV     16

#define STAT_TR_IDLE 22

#define STAT_TR_RDY  24

struct etrax_serial

{

    SysBusDevice busdev;

    CharDriverState *chr;

    qemu_irq irq;

    int pending_tx;

    uint8_t rx_fifo[16];

    unsigned int rx_fifo_pos;

    unsigned int rx_fifo_len;

    /* Control registers.  */

    uint32_t regs[R_MAX];

};

static void ser_update_irq(struct etrax_serial *s)

{

    if (s->rx_fifo_len) {

        s->regs[R_INTR] |= 8;

    } else {

        s->regs[R_INTR] &= ~8;

    }

    s->regs[R_MASKED_INTR] = s->regs[R_INTR] & s->regs[RW_INTR_MASK];

    qemu_set_irq(s->irq, !!s->regs[R_MASKED_INTR]);

}

static uint32_t ser_readl (void *opaque, target_phys_addr_t addr)

{

    struct etrax_serial *s = opaque;

    D(CPUState *env = s->env);

    uint32_t r = 0;

    addr >>= 2;

    switch (addr)

    {

        case R_STAT_DIN:

            r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 15];

            if (s->rx_fifo_len) {

                r |= 1 << STAT_DAV;

            }

            r |= 1 << STAT_TR_RDY;

            r |= 1 << STAT_TR_IDLE;

            break;

        case RS_STAT_DIN:

            r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 15];

            if (s->rx_fifo_len) {

                r |= 1 << STAT_DAV;

                s->rx_fifo_len--;

            }

            r |= 1 << STAT_TR_RDY;

            r |= 1 << STAT_TR_IDLE;

            break;

        default:

            r = s->regs[addr];

            D(printf ("%s " TARGET_FMT_plx "=%x\n", __func__, addr, r));

            break;

    }

    return r;

}

static void

ser_writel (void *opaque, target_phys_addr_t addr, uint32_t value)

{

    struct etrax_serial *s = opaque;

    unsigned char ch = value;

    D(CPUState *env = s->env);

    D(printf ("%s " TARGET_FMT_plx "=%x\n",  __func__, addr, value));

    addr >>= 2;

    switch (addr)

    {

        case RW_DOUT:

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

            s->regs[R_INTR] |= 3;

            s->pending_tx = 1;

            s->regs[addr] = value;

            break;

        case RW_ACK_INTR:

            if (s->pending_tx) {

                value &= ~1;

                s->pending_tx = 0;

                D(printf("fixedup value=%x r_intr=%x\n", value, s->regs[R_INTR]));

            }

            s->regs[addr] = value;

            s->regs[R_INTR] &= ~value;

            D(printf("r_intr=%x\n", s->regs[R_INTR]));

            break;

        default:

            s->regs[addr] = value;

            break;

    }

    ser_update_irq(s);

}

static CPUReadMemoryFunc * const ser_read[] = {

    NULL, NULL,

    &ser_readl,

};

static CPUWriteMemoryFunc * const ser_write[] = {

    NULL, NULL,

    &ser_writel,

};

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

{

    struct etrax_serial *s = opaque;

    int i;

    /* Got a byte.  */

    if (s->rx_fifo_len >= 16) {

        printf("WARNING: UART dropped char.\n");

        return;

    }

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

        s->rx_fifo[s->rx_fifo_pos] = buf[i];

        s->rx_fifo_pos++;

        s->rx_fifo_pos &= 15;

        s->rx_fifo_len++;

    }

    ser_update_irq(s);

}

static int serial_can_receive(void *opaque)

{

    struct etrax_serial *s = opaque;

    int r;

    /* Is the receiver enabled?  */

    if (!(s->regs[RW_REC_CTRL] & (1 << 3))) {

        return 0;

    }

    r = sizeof(s->rx_fifo) - s->rx_fifo_len;

    return r;

}

static void serial_event(void *opaque, int event)

{

}

static int etraxfs_ser_init(SysBusDevice *dev)

{

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

    int ser_regs;

    /* transmitter begins ready and idle.  */

    s->regs[RS_STAT_DIN] |= (1 << STAT_TR_RDY);

    s->regs[RS_STAT_DIN] |= (1 << STAT_TR_IDLE);

    sysbus_init_irq(dev, &s->irq);

    ser_regs = cpu_register_io_memory(ser_read, ser_write, s,

                                      DEVICE_NATIVE_ENDIAN);

    sysbus_init_mmio(dev, R_MAX * 4, ser_regs);

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

    if (s->chr)

        qemu_chr_add_handlers(s->chr,

                      serial_can_receive, serial_receive,

                      serial_event, s);

    return 0;

}

static void etraxfs_serial_register(void)

{

    sysbus_register_dev("etraxfs,serial", sizeof (struct etrax_serial),

                etraxfs_ser_init);

}

device_init(etraxfs_serial_register)