/*

 * ColdFire UART emulation.

 *

 * Copyright (c) 2007 CodeSourcery.

 *

 * This code is licenced under the GPL

 */

#include "hw.h"

#include "mcf.h"

#include "qemu-char.h"

typedef struct {

    uint8_t mr[2];

    uint8_t sr;

    uint8_t isr;

    uint8_t imr;

    uint8_t bg1;

    uint8_t bg2;

    uint8_t fifo[4];

    uint8_t tb;

    int current_mr;

    int fifo_len;

    int tx_enabled;

    int rx_enabled;

    qemu_irq irq;

    CharDriverState *chr;

} mcf_uart_state;

/* UART Status Register bits.  */

#define MCF_UART_RxRDY  0x01

#define MCF_UART_FFULL  0x02

#define MCF_UART_TxRDY  0x04

#define MCF_UART_TxEMP  0x08

#define MCF_UART_OE     0x10

#define MCF_UART_PE     0x20

#define MCF_UART_FE     0x40

#define MCF_UART_RB     0x80

/* Interrupt flags.  */

#define MCF_UART_TxINT  0x01

#define MCF_UART_RxINT  0x02

#define MCF_UART_DBINT  0x04

#define MCF_UART_COSINT 0x80

/* UMR1 flags.  */

#define MCF_UART_BC0    0x01

#define MCF_UART_BC1    0x02

#define MCF_UART_PT     0x04

#define MCF_UART_PM0    0x08

#define MCF_UART_PM1    0x10

#define MCF_UART_ERR    0x20

#define MCF_UART_RxIRQ  0x40

#define MCF_UART_RxRTS  0x80

static void mcf_uart_update(mcf_uart_state *s)

{

    s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT);

    if (s->sr & MCF_UART_TxRDY)

        s->isr |= MCF_UART_TxINT;

    if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ)

                  ? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0)

        s->isr |= MCF_UART_RxINT;

    qemu_set_irq(s->irq, (s->isr & s->imr) != 0);

}

uint32_t mcf_uart_read(void *opaque, target_phys_addr_t addr)

{

    mcf_uart_state *s = (mcf_uart_state *)opaque;

    switch (addr & 0x3f) {

    case 0x00:

        return s->mr[s->current_mr];

    case 0x04:

        return s->sr;

    case 0x0c:

        {

            uint8_t val;

            int i;

            if (s->fifo_len == 0)

                return 0;

            val = s->fifo[0];

            s->fifo_len--;

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

                s->fifo[i] = s->fifo[i + 1];

            s->sr &= ~MCF_UART_FFULL;

            if (s->fifo_len == 0)

                s->sr &= ~MCF_UART_RxRDY;

            mcf_uart_update(s);

            qemu_chr_accept_input(s->chr);

            return val;

        }

    case 0x10:

        /* TODO: Implement IPCR.  */

        return 0;

    case 0x14:

        return s->isr;

    case 0x18:

        return s->bg1;

    case 0x1c:

        return s->bg2;

    default:

        return 0;

    }

}

/* Update TxRDY flag and set data if present and enabled.  */

static void mcf_uart_do_tx(mcf_uart_state *s)

{

    if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) {

        if (s->chr)

            qemu_chr_write(s->chr, (unsigned char *)&s->tb, 1);

        s->sr |= MCF_UART_TxEMP;

    }

    if (s->tx_enabled) {

        s->sr |= MCF_UART_TxRDY;

    } else {

        s->sr &= ~MCF_UART_TxRDY;

    }

}

static void mcf_do_command(mcf_uart_state *s, uint8_t cmd)

{

    /* Misc command.  */

    switch ((cmd >> 4) & 3) {

    case 0: /* No-op.  */

        break;

    case 1: /* Reset mode register pointer.  */

        s->current_mr = 0;

        break;

    case 2: /* Reset receiver.  */

        s->rx_enabled = 0;

        s->fifo_len = 0;

        s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL);

        break;

    case 3: /* Reset transmitter.  */

        s->tx_enabled = 0;

        s->sr |= MCF_UART_TxEMP;

        s->sr &= ~MCF_UART_TxRDY;

        break;

    case 4: /* Reset error status.  */

        break;

    case 5: /* Reset break-change interrupt.  */

        s->isr &= ~MCF_UART_DBINT;

        break;

    case 6: /* Start break.  */

    case 7: /* Stop break.  */

        break;

    }

    /* Transmitter command.  */

    switch ((cmd >> 2) & 3) {

    case 0: /* No-op.  */

        break;

    case 1: /* Enable.  */

        s->tx_enabled = 1;

        mcf_uart_do_tx(s);

        break;

    case 2: /* Disable.  */

        s->tx_enabled = 0;

        mcf_uart_do_tx(s);

        break;

    case 3: /* Reserved.  */

        fprintf(stderr, "mcf_uart: Bad TX command\n");

        break;

    }

    /* Receiver command.  */

    switch (cmd & 3) {

    case 0: /* No-op.  */

        break;

    case 1: /* Enable.  */

        s->rx_enabled = 1;

        break;

    case 2:

        s->rx_enabled = 0;

        break;

    case 3: /* Reserved.  */

        fprintf(stderr, "mcf_uart: Bad RX command\n");

        break;

    }

}

void mcf_uart_write(void *opaque, target_phys_addr_t addr, uint32_t val)

{

    mcf_uart_state *s = (mcf_uart_state *)opaque;

    switch (addr & 0x3f) {

    case 0x00:

        s->mr[s->current_mr] = val;

        s->current_mr = 1;

        break;

    case 0x04:

        /* CSR is ignored.  */

        break;

    case 0x08: /* Command Register.  */

        mcf_do_command(s, val);

        break;

    case 0x0c: /* Transmit Buffer.  */

        s->sr &= ~MCF_UART_TxEMP;

        s->tb = val;

        mcf_uart_do_tx(s);

        break;

    case 0x10:

        /* ACR is ignored.  */

        break;

    case 0x14:

        s->imr = val;

        break;

    default:

        break;

    }

    mcf_uart_update(s);

}

static void mcf_uart_reset(mcf_uart_state *s)

{

    s->fifo_len = 0;

    s->mr[0] = 0;

    s->mr[1] = 0;

    s->sr = MCF_UART_TxEMP;

    s->tx_enabled = 0;

    s->rx_enabled = 0;

    s->isr = 0;

    s->imr = 0;

}

static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data)

{

    /* Break events overwrite the last byte if the fifo is full.  */

    if (s->fifo_len == 4)

        s->fifo_len--;

    s->fifo[s->fifo_len] = data;

    s->fifo_len++;

    s->sr |= MCF_UART_RxRDY;

    if (s->fifo_len == 4)

        s->sr |= MCF_UART_FFULL;

    mcf_uart_update(s);

}

static void mcf_uart_event(void *opaque, int event)

{

    mcf_uart_state *s = (mcf_uart_state *)opaque;

    switch (event) {

    case CHR_EVENT_BREAK:

        s->isr |= MCF_UART_DBINT;

        mcf_uart_push_byte(s, 0);

        break;

    default:

        break;

    }

}

static int mcf_uart_can_receive(void *opaque)

{

    mcf_uart_state *s = (mcf_uart_state *)opaque;

    return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0;

}

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

{

    mcf_uart_state *s = (mcf_uart_state *)opaque;

    mcf_uart_push_byte(s, buf[0]);

}

void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)

{

    mcf_uart_state *s;

    s = qemu_mallocz(sizeof(mcf_uart_state));

    s->chr = chr;

    s->irq = irq;

    if (chr) {

        qemu_chr_add_handlers(chr, mcf_uart_can_receive, mcf_uart_receive,

                              mcf_uart_event, s);

    }

    mcf_uart_reset(s);

    return s;

}

static CPUReadMemoryFunc *mcf_uart_readfn[] = {

   mcf_uart_read,

   mcf_uart_read,

   mcf_uart_read

};

static CPUWriteMemoryFunc *mcf_uart_writefn[] = {

   mcf_uart_write,

   mcf_uart_write,

   mcf_uart_write

};

void mcf_uart_mm_init(target_phys_addr_t base, qemu_irq irq,

                      CharDriverState *chr)

{

    mcf_uart_state *s;

    int iomemtype;

    s = mcf_uart_init(irq, chr);

    iomemtype = cpu_register_io_memory(0, mcf_uart_readfn,

                                       mcf_uart_writefn, s);

    cpu_register_physical_memory(base, 0x40, iomemtype);

}