Archipelago » qemu

/*

 * QEMU model of Xilinx uartlite.

 *

 * Copyright (c) 2009 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-char.h"

#define DUART(x)

#define R_RX            0

#define R_TX            1

#define R_STATUS        2

#define R_CTRL          3

#define R_MAX           4

#define STATUS_RXVALID    0x01

#define STATUS_RXFULL     0x02

#define STATUS_TXEMPTY    0x04

#define STATUS_TXFULL     0x08

#define STATUS_IE         0x10

#define STATUS_OVERRUN    0x20

#define STATUS_FRAME      0x40

#define STATUS_PARITY     0x80

#define CONTROL_RST_TX    0x01

#define CONTROL_RST_RX    0x02

#define CONTROL_IE        0x10

struct xlx_uartlite

{

    SysBusDevice busdev;

    CharDriverState *chr;

    qemu_irq irq;

    uint8_t rx_fifo[8];

    unsigned int rx_fifo_pos;

    unsigned int rx_fifo_len;

    uint32_t regs[R_MAX];

};

static void uart_update_irq(struct xlx_uartlite *s)

{

    unsigned int irq;

    if (s->rx_fifo_len)

        s->regs[R_STATUS] |= STATUS_IE;

    irq = (s->regs[R_STATUS] & STATUS_IE) && (s->regs[R_CTRL] & CONTROL_IE);

    qemu_set_irq(s->irq, irq);

}

static void uart_update_status(struct xlx_uartlite *s)

{

    uint32_t r;

    r = s->regs[R_STATUS];

    r &= ~7;

    r |= 1 << 2; /* Tx fifo is always empty. We are fast :) */

    r |= (s->rx_fifo_len == sizeof (s->rx_fifo)) << 1;

    r |= (!!s->rx_fifo_len);

    s->regs[R_STATUS] = r;

}

static uint32_t uart_readl (void *opaque, target_phys_addr_t addr)

{

    struct xlx_uartlite *s = opaque;

    uint32_t r = 0;

    addr >>= 2;

    switch (addr)

    {

        case R_RX:

            r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 7];

            if (s->rx_fifo_len)

                s->rx_fifo_len--;

            uart_update_status(s);

            uart_update_irq(s);

            break;

        default:

            if (addr < ARRAY_SIZE(s->regs))

                r = s->regs[addr];

            DUART(qemu_log("%s addr=%x v=%x\n", __func__, addr, r));

            break;

    }

    return r;

}

static void

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

{

    struct xlx_uartlite *s = opaque;

    unsigned char ch = value;

    addr >>= 2;

    switch (addr)

    {

        case R_STATUS:

            hw_error("write to UART STATUS?\n");

            break;

        case R_CTRL:

            if (value & CONTROL_RST_RX) {

                s->rx_fifo_pos = 0;

                s->rx_fifo_len = 0;

            }

            s->regs[addr] = value;

            break;

        case R_TX:

            if (s->chr)

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

            s->regs[addr] = value;

            /* hax.  */

            s->regs[R_STATUS] |= STATUS_IE;

            break;

        default:

            DUART(printf("%s addr=%x v=%x\n", __func__, addr, value));

            if (addr < ARRAY_SIZE(s->regs))

                s->regs[addr] = value;

            break;

    }

    uart_update_status(s);

    uart_update_irq(s);

}

static CPUReadMemoryFunc *uart_read[] = {

    &uart_readl,

    &uart_readl,

    &uart_readl,

};

static CPUWriteMemoryFunc *uart_write[] = {

    &uart_writel,

    &uart_writel,

    &uart_writel,

};

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

{

    struct xlx_uartlite *s = opaque;

    /* Got a byte.  */

    if (s->rx_fifo_len >= 8) {

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

        return;

    }

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

    s->rx_fifo_pos++;

    s->rx_fifo_pos &= 0x7;

    s->rx_fifo_len++;

    uart_update_status(s);

    uart_update_irq(s);

}

static int uart_can_rx(void *opaque)

{

    struct xlx_uartlite *s = opaque;

    int r;

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

    if (!r)

        printf("cannot receive!\n");

    return r;

}

static void uart_event(void *opaque, int event)

{

}

static void xilinx_uartlite_init(SysBusDevice *dev)

{

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

    int uart_regs;

    sysbus_init_irq(dev, &s->irq);

    uart_update_status(s);

    uart_regs = cpu_register_io_memory(0, uart_read, uart_write, s);

    sysbus_init_mmio(dev, R_MAX * 4, uart_regs);

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

    if (s->chr)

        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);

}

static void xilinx_uart_register(void)

{

    sysbus_register_dev("xilinx,uartlite", sizeof (struct xlx_uartlite),

                        xilinx_uartlite_init);

}

device_init(xilinx_uart_register)