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/*
* QEMU model of the Milkymist UART block.
*
* Copyright (c) 2010 Michael Walle <michael@walle.cc>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*
* Specification available at:
* http://www.milkymist.org/socdoc/uart.pdf
*/
#include "hw.h"
#include "sysbus.h"
#include "trace.h"
#include "qemu-char.h"
#include "qemu-error.h"
enum {
R_RXTX = 0,
R_DIV,
R_STAT,
R_CTRL,
R_DBG,
R_MAX
};
enum {
STAT_THRE = (1<<0),
STAT_RX_EVT = (1<<1),
STAT_TX_EVT = (1<<2),
};
enum {
CTRL_RX_IRQ_EN = (1<<0),
CTRL_TX_IRQ_EN = (1<<1),
CTRL_THRU_EN = (1<<2),
};
enum {
DBG_BREAK_EN = (1<<0),
};
struct MilkymistUartState {
SysBusDevice busdev;
CharDriverState *chr;
qemu_irq irq;
uint32_t regs[R_MAX];
};
typedef struct MilkymistUartState MilkymistUartState;
static void uart_update_irq(MilkymistUartState *s)
{
int rx_event = s->regs[R_STAT] & STAT_RX_EVT;
int tx_event = s->regs[R_STAT] & STAT_TX_EVT;
int rx_irq_en = s->regs[R_CTRL] & CTRL_RX_IRQ_EN;
int tx_irq_en = s->regs[R_CTRL] & CTRL_TX_IRQ_EN;
if ((rx_irq_en && rx_event) || (tx_irq_en && tx_event)) {
trace_milkymist_uart_raise_irq();
qemu_irq_raise(s->irq);
} else {
trace_milkymist_uart_lower_irq();
qemu_irq_lower(s->irq);
}
}
static uint32_t uart_read(void *opaque, target_phys_addr_t addr)
{
MilkymistUartState *s = opaque;
uint32_t r = 0;
addr >>= 2;
switch (addr) {
case R_RXTX:
r = s->regs[addr];
break;
case R_DIV:
case R_STAT:
case R_CTRL:
case R_DBG:
r = s->regs[addr];
break;
default:
error_report("milkymist_uart: read access to unknown register 0x"
TARGET_FMT_plx, addr << 2);
break;
}
trace_milkymist_uart_memory_read(addr << 2, r);
return r;
}
static void uart_write(void *opaque, target_phys_addr_t addr, uint32_t value)
{
MilkymistUartState *s = opaque;
unsigned char ch = value;
trace_milkymist_uart_memory_write(addr, value);
addr >>= 2;
switch (addr) {
case R_RXTX:
if (s->chr) {
qemu_chr_fe_write(s->chr, &ch, 1);
}
s->regs[R_STAT] |= STAT_TX_EVT;
break;
case R_DIV:
case R_CTRL:
case R_DBG:
s->regs[addr] = value;
break;
case R_STAT:
/* write one to clear bits */
s->regs[addr] &= ~(value & (STAT_RX_EVT | STAT_TX_EVT));
break;
default:
error_report("milkymist_uart: write access to unknown register 0x"
TARGET_FMT_plx, addr << 2);
break;
}
uart_update_irq(s);
}
static CPUReadMemoryFunc * const uart_read_fn[] = {
NULL,
NULL,
&uart_read,
};
static CPUWriteMemoryFunc * const uart_write_fn[] = {
NULL,
NULL,
&uart_write,
};
static void uart_rx(void *opaque, const uint8_t *buf, int size)
{
MilkymistUartState *s = opaque;
assert(!(s->regs[R_STAT] & STAT_RX_EVT));
s->regs[R_STAT] |= STAT_RX_EVT;
s->regs[R_RXTX] = *buf;
uart_update_irq(s);
}
static int uart_can_rx(void *opaque)
{
MilkymistUartState *s = opaque;
return !(s->regs[R_STAT] & STAT_RX_EVT);
}
static void uart_event(void *opaque, int event)
{
}
static void milkymist_uart_reset(DeviceState *d)
{
MilkymistUartState *s = container_of(d, MilkymistUartState, busdev.qdev);
int i;
for (i = 0; i < R_MAX; i++) {
s->regs[i] = 0;
}
/* THRE is always set */
s->regs[R_STAT] = STAT_THRE;
}
static int milkymist_uart_init(SysBusDevice *dev)
{
MilkymistUartState *s = FROM_SYSBUS(typeof(*s), dev);
int uart_regs;
sysbus_init_irq(dev, &s->irq);
uart_regs = cpu_register_io_memory(uart_read_fn, uart_write_fn, s,
DEVICE_NATIVE_ENDIAN);
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);
}
return 0;
}
static const VMStateDescription vmstate_milkymist_uart = {
.name = "milkymist-uart",
.version_id = 1,
.minimum_version_id = 1,
.minimum_version_id_old = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT32_ARRAY(regs, MilkymistUartState, R_MAX),
VMSTATE_END_OF_LIST()
}
};
static SysBusDeviceInfo milkymist_uart_info = {
.init = milkymist_uart_init,
.qdev.name = "milkymist-uart",
.qdev.size = sizeof(MilkymistUartState),
.qdev.vmsd = &vmstate_milkymist_uart,
.qdev.reset = milkymist_uart_reset,
};
static void milkymist_uart_register(void)
{
sysbus_register_withprop(&milkymist_uart_info);
}
device_init(milkymist_uart_register)
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