qemu-e2k/hw/mcf_uart.c

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/*
* 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 * const mcf_uart_readfn[] = {
mcf_uart_read,
mcf_uart_read,
mcf_uart_read
};
static CPUWriteMemoryFunc * const 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(mcf_uart_readfn,
mcf_uart_writefn, s);
cpu_register_physical_memory(base, 0x40, iomemtype);
}