hw/char/xilinx_uartlite.c

   1 /*
   2  * QEMU model of Xilinx uartlite.
   3  *
   4  * Copyright (c) 2009 Edgar E. Iglesias.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "hw/sysbus.h"
  27 #include "chardev/char-fe.h"
  28
  29 #define DUART(x)
  30
  31 #define R_RX            0
  32 #define R_TX            1
  33 #define R_STATUS        2
  34 #define R_CTRL          3
  35 #define R_MAX           4
  36
  37 #define STATUS_RXVALID    0x01
  38 #define STATUS_RXFULL     0x02
  39 #define STATUS_TXEMPTY    0x04
  40 #define STATUS_TXFULL     0x08
  41 #define STATUS_IE         0x10
  42 #define STATUS_OVERRUN    0x20
  43 #define STATUS_FRAME      0x40
  44 #define STATUS_PARITY     0x80
  45
  46 #define CONTROL_RST_TX    0x01
  47 #define CONTROL_RST_RX    0x02
  48 #define CONTROL_IE        0x10
  49
  50 #define TYPE_XILINX_UARTLITE "xlnx.xps-uartlite"
  51 #define XILINX_UARTLITE(obj) \
  52     OBJECT_CHECK(XilinxUARTLite, (obj), TYPE_XILINX_UARTLITE)
  53
  54 typedef struct XilinxUARTLite {
  55     SysBusDevice parent_obj;
  56
  57     MemoryRegion mmio;
  58     CharBackend chr;
  59     qemu_irq irq;
  60
  61     uint8_t rx_fifo[8];
  62     unsigned int rx_fifo_pos;
  63     unsigned int rx_fifo_len;
  64
  65     uint32_t regs[R_MAX];
  66 } XilinxUARTLite;
  67
  68 static void uart_update_irq(XilinxUARTLite *s)
  69 {
  70     unsigned int irq;
  71
  72     if (s->rx_fifo_len)
  73         s->regs[R_STATUS] |= STATUS_IE;
  74
  75     irq = (s->regs[R_STATUS] & STATUS_IE) && (s->regs[R_CTRL] & CONTROL_IE);
  76     qemu_set_irq(s->irq, irq);
  77 }
  78
  79 static void uart_update_status(XilinxUARTLite *s)
  80 {
  81     uint32_t r;
  82
  83     r = s->regs[R_STATUS];
  84     r &= ~7;
  85     r |= 1 << 2; /* Tx fifo is always empty. We are fast :) */
  86     r |= (s->rx_fifo_len == sizeof (s->rx_fifo)) << 1;
  87     r |= (!!s->rx_fifo_len);
  88     s->regs[R_STATUS] = r;
  89 }
  90
  91 static void xilinx_uartlite_reset(DeviceState *dev)
  92 {
  93     uart_update_status(XILINX_UARTLITE(dev));
  94 }
  95
  96 static uint64_t
  97 uart_read(void *opaque, hwaddr addr, unsigned int size)
  98 {
  99     XilinxUARTLite *s = opaque;
 100     uint32_t r = 0;
 101     addr >>= 2;
 102     switch (addr)
 103     {
 104         case R_RX:
 105             r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 7];
 106             if (s->rx_fifo_len)
 107                 s->rx_fifo_len--;
 108             uart_update_status(s);
 109             uart_update_irq(s);
 110             qemu_chr_fe_accept_input(&s->chr);
 111             break;
 112
 113         default:
 114             if (addr < ARRAY_SIZE(s->regs))
 115                 r = s->regs[addr];
 116             DUART(qemu_log("%s addr=%x v=%x\n", __func__, addr, r));
 117             break;
 118     }
 119     return r;
 120 }
 121
 122 static void
 123 uart_write(void *opaque, hwaddr addr,
 124            uint64_t val64, unsigned int size)
 125 {
 126     XilinxUARTLite *s = opaque;
 127     uint32_t value = val64;
 128     unsigned char ch = value;
 129
 130     addr >>= 2;
 131     switch (addr)
 132     {
 133         case R_STATUS:
 134             hw_error("write to UART STATUS?\n");
 135             break;
 136
 137         case R_CTRL:
 138             if (value & CONTROL_RST_RX) {
 139                 s->rx_fifo_pos = 0;
 140                 s->rx_fifo_len = 0;
 141             }
 142             s->regs[addr] = value;
 143             break;
 144
 145         case R_TX:
 146             /* XXX this blocks entire thread. Rewrite to use
 147              * qemu_chr_fe_write and background I/O callbacks */
 148             qemu_chr_fe_write_all(&s->chr, &ch, 1);
 149             s->regs[addr] = value;
 150
 151             /* hax.  */
 152             s->regs[R_STATUS] |= STATUS_IE;
 153             break;
 154
 155         default:
 156             DUART(printf("%s addr=%x v=%x\n", __func__, addr, value));
 157             if (addr < ARRAY_SIZE(s->regs))
 158                 s->regs[addr] = value;
 159             break;
 160     }
 161     uart_update_status(s);
 162     uart_update_irq(s);
 163 }
 164
 165 static const MemoryRegionOps uart_ops = {
 166     .read = uart_read,
 167     .write = uart_write,
 168     .endianness = DEVICE_NATIVE_ENDIAN,
 169     .valid = {
 170         .min_access_size = 1,
 171         .max_access_size = 4
 172     }
 173 };
 174
 175 static Property xilinx_uartlite_properties[] = {
 176     DEFINE_PROP_CHR("chardev", XilinxUARTLite, chr),
 177     DEFINE_PROP_END_OF_LIST(),
 178 };
 179
 180 static void uart_rx(void *opaque, const uint8_t *buf, int size)
 181 {
 182     XilinxUARTLite *s = opaque;
 183
 184     /* Got a byte.  */
 185     if (s->rx_fifo_len >= 8) {
 186         printf("WARNING: UART dropped char.\n");
 187         return;
 188     }
 189     s->rx_fifo[s->rx_fifo_pos] = *buf;
 190     s->rx_fifo_pos++;
 191     s->rx_fifo_pos &= 0x7;
 192     s->rx_fifo_len++;
 193
 194     uart_update_status(s);
 195     uart_update_irq(s);
 196 }
 197
 198 static int uart_can_rx(void *opaque)
 199 {
 200     XilinxUARTLite *s = opaque;
 201
 202     return s->rx_fifo_len < sizeof(s->rx_fifo);
 203 }
 204
 205 static void uart_event(void *opaque, int event)
 206 {
 207
 208 }
 209
 210 static void xilinx_uartlite_realize(DeviceState *dev, Error **errp)
 211 {
 212     XilinxUARTLite *s = XILINX_UARTLITE(dev);
 213
 214     qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx,
 215                              uart_event, NULL, s, NULL, true);
 216 }
 217
 218 static void xilinx_uartlite_init(Object *obj)
 219 {
 220     XilinxUARTLite *s = XILINX_UARTLITE(obj);
 221
 222     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
 223
 224     memory_region_init_io(&s->mmio, obj, &uart_ops, s,
 225                           "xlnx.xps-uartlite", R_MAX * 4);
 226     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
 227 }
 228
 229 static void xilinx_uartlite_class_init(ObjectClass *klass, void *data)
 230 {
 231     DeviceClass *dc = DEVICE_CLASS(klass);
 232
 233     dc->reset = xilinx_uartlite_reset;
 234     dc->realize = xilinx_uartlite_realize;
 235     dc->props = xilinx_uartlite_properties;
 236 }
 237
 238 static const TypeInfo xilinx_uartlite_info = {
 239     .name          = TYPE_XILINX_UARTLITE,
 240     .parent        = TYPE_SYS_BUS_DEVICE,
 241     .instance_size = sizeof(XilinxUARTLite),
 242     .instance_init = xilinx_uartlite_init,
 243     .class_init    = xilinx_uartlite_class_init,
 244 };
 245
 246 static void xilinx_uart_register_types(void)
 247 {
 248     type_register_static(&xilinx_uartlite_info);
 249 }
 250
 251 type_init(xilinx_uart_register_types)