hw/milkymist-uart.c

   1 /*
   2  *  QEMU model of the Milkymist UART block.
   3  *
   4  *  Copyright (c) 2010 Michael Walle <michael@walle.cc>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  *
  20  * Specification available at:
  21  *   http://www.milkymist.org/socdoc/uart.pdf
  22  */
  23
  24 #include "hw.h"
  25 #include "sysbus.h"
  26 #include "trace.h"
  27 #include "qemu-char.h"
  28 #include "qemu-error.h"
  29
  30 enum {
  31     R_RXTX = 0,
  32     R_DIV,
  33     R_MAX
  34 };
  35
  36 struct MilkymistUartState {
  37     SysBusDevice busdev;
  38     CharDriverState *chr;
  39     qemu_irq rx_irq;
  40     qemu_irq tx_irq;
  41
  42     uint32_t regs[R_MAX];
  43 };
  44 typedef struct MilkymistUartState MilkymistUartState;
  45
  46 static uint32_t uart_read(void *opaque, target_phys_addr_t addr)
  47 {
  48     MilkymistUartState *s = opaque;
  49     uint32_t r = 0;
  50
  51     addr >>= 2;
  52     switch (addr) {
  53     case R_RXTX:
  54     case R_DIV:
  55         r = s->regs[addr];
  56         break;
  57
  58     default:
  59         error_report("milkymist_uart: read access to unknown register 0x"
  60                 TARGET_FMT_plx, addr << 2);
  61         break;
  62     }
  63
  64     trace_milkymist_uart_memory_read(addr << 2, r);
  65
  66     return r;
  67 }
  68
  69 static void uart_write(void *opaque, target_phys_addr_t addr, uint32_t value)
  70 {
  71     MilkymistUartState *s = opaque;
  72     unsigned char ch = value;
  73
  74     trace_milkymist_uart_memory_write(addr, value);
  75
  76     addr >>= 2;
  77     switch (addr) {
  78     case R_RXTX:
  79         if (s->chr) {
  80             qemu_chr_fe_write(s->chr, &ch, 1);
  81         }
  82         trace_milkymist_uart_pulse_irq_tx();
  83         qemu_irq_pulse(s->tx_irq);
  84         break;
  85     case R_DIV:
  86         s->regs[addr] = value;
  87         break;
  88
  89     default:
  90         error_report("milkymist_uart: write access to unknown register 0x"
  91                 TARGET_FMT_plx, addr << 2);
  92         break;
  93     }
  94 }
  95
  96 static CPUReadMemoryFunc * const uart_read_fn[] = {
  97     NULL,
  98     NULL,
  99     &uart_read,
 100 };
 101
 102 static CPUWriteMemoryFunc * const uart_write_fn[] = {
 103     NULL,
 104     NULL,
 105     &uart_write,
 106 };
 107
 108 static void uart_rx(void *opaque)
 109 {
 110     MilkymistUartState *s = opaque;
 111     uint8_t buf[1];
 112
 113     if (qemu_chr_fe_read(s->chr, buf, 1) == 0) {
 114         return;
 115     }
 116
 117     s->regs[R_RXTX] = buf[0];
 118     trace_milkymist_uart_pulse_irq_rx();
 119     qemu_irq_pulse(s->rx_irq);
 120 }
 121
 122 static void milkymist_uart_reset(DeviceState *d)
 123 {
 124     MilkymistUartState *s = container_of(d, MilkymistUartState, busdev.qdev);
 125     int i;
 126
 127     for (i = 0; i < R_MAX; i++) {
 128         s->regs[i] = 0;
 129     }
 130 }
 131
 132 static int milkymist_uart_init(SysBusDevice *dev)
 133 {
 134     MilkymistUartState *s = FROM_SYSBUS(typeof(*s), dev);
 135     int uart_regs;
 136
 137     sysbus_init_irq(dev, &s->rx_irq);
 138     sysbus_init_irq(dev, &s->tx_irq);
 139
 140     uart_regs = cpu_register_io_memory(uart_read_fn, uart_write_fn, s,
 141             DEVICE_NATIVE_ENDIAN);
 142     sysbus_init_mmio(dev, R_MAX * 4, uart_regs);
 143
 144     s->chr = qdev_init_chardev(&dev->qdev);
 145     if (s->chr) {
 146         qemu_chr_fe_open(s->chr);
 147         qemu_chr_fe_set_handlers(s->chr, uart_rx, NULL, NULL, s);
 148     }
 149
 150     return 0;
 151 }
 152
 153 static const VMStateDescription vmstate_milkymist_uart = {
 154     .name = "milkymist-uart",
 155     .version_id = 1,
 156     .minimum_version_id = 1,
 157     .minimum_version_id_old = 1,
 158     .fields      = (VMStateField[]) {
 159         VMSTATE_UINT32_ARRAY(regs, MilkymistUartState, R_MAX),
 160         VMSTATE_END_OF_LIST()
 161     }
 162 };
 163
 164 static SysBusDeviceInfo milkymist_uart_info = {
 165     .init = milkymist_uart_init,
 166     .qdev.name  = "milkymist-uart",
 167     .qdev.size  = sizeof(MilkymistUartState),
 168     .qdev.vmsd  = &vmstate_milkymist_uart,
 169     .qdev.reset = milkymist_uart_reset,
 170 };
 171
 172 static void milkymist_uart_register(void)
 173 {
 174     sysbus_register_withprop(&milkymist_uart_info);
 175 }
 176
 177 device_init(milkymist_uart_register)