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/*
* 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;
MemoryRegion mmio;
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 uint64_t
uart_read(void *opaque, target_phys_addr_t addr, unsigned int size)
{
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_write(void *opaque, target_phys_addr_t addr,
uint64_t val64, unsigned int size)
{
struct xlx_uartlite *s = opaque;
uint32_t value = val64;
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_fe_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 const MemoryRegionOps uart_ops = {
.read = uart_read,
.write = uart_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.valid = {
.min_access_size = 1,
.max_access_size = 4
}
};
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 int xilinx_uartlite_init(SysBusDevice *dev)
{
struct xlx_uartlite *s = FROM_SYSBUS(typeof (*s), dev);
sysbus_init_irq(dev, &s->irq);
uart_update_status(s);
memory_region_init_io(&s->mmio, &uart_ops, s, "xilinx-uartlite", R_MAX * 4);
sysbus_init_mmio(dev, &s->mmio);
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 void xilinx_uart_register(void)
{
sysbus_register_dev("xilinx,uartlite", sizeof (struct xlx_uartlite),
xilinx_uartlite_init);
}
device_init(xilinx_uart_register)
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