hw/char/mcf_uart.c

   1 /*
   2  * ColdFire UART emulation.
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  *
   6  * This code is licensed under the GPL
   7  */
   8 #include "qemu/osdep.h"
   9 #include "hw/hw.h"
  10 #include "hw/sysbus.h"
  11 #include "hw/m68k/mcf.h"
  12 #include "chardev/char-fe.h"
  13 #include "exec/address-spaces.h"
  14 #include "qapi/error.h"
  15
  16 typedef struct {
  17     SysBusDevice parent_obj;
  18
  19     MemoryRegion iomem;
  20     uint8_t mr[2];
  21     uint8_t sr;
  22     uint8_t isr;
  23     uint8_t imr;
  24     uint8_t bg1;
  25     uint8_t bg2;
  26     uint8_t fifo[4];
  27     uint8_t tb;
  28     int current_mr;
  29     int fifo_len;
  30     int tx_enabled;
  31     int rx_enabled;
  32     qemu_irq irq;
  33     CharBackend chr;
  34 } mcf_uart_state;
  35
  36 #define TYPE_MCF_UART "mcf-uart"
  37 #define MCF_UART(obj) OBJECT_CHECK(mcf_uart_state, (obj), TYPE_MCF_UART)
  38
  39 /* UART Status Register bits.  */
  40 #define MCF_UART_RxRDY  0x01
  41 #define MCF_UART_FFULL  0x02
  42 #define MCF_UART_TxRDY  0x04
  43 #define MCF_UART_TxEMP  0x08
  44 #define MCF_UART_OE     0x10
  45 #define MCF_UART_PE     0x20
  46 #define MCF_UART_FE     0x40
  47 #define MCF_UART_RB     0x80
  48
  49 /* Interrupt flags.  */
  50 #define MCF_UART_TxINT  0x01
  51 #define MCF_UART_RxINT  0x02
  52 #define MCF_UART_DBINT  0x04
  53 #define MCF_UART_COSINT 0x80
  54
  55 /* UMR1 flags.  */
  56 #define MCF_UART_BC0    0x01
  57 #define MCF_UART_BC1    0x02
  58 #define MCF_UART_PT     0x04
  59 #define MCF_UART_PM0    0x08
  60 #define MCF_UART_PM1    0x10
  61 #define MCF_UART_ERR    0x20
  62 #define MCF_UART_RxIRQ  0x40
  63 #define MCF_UART_RxRTS  0x80
  64
  65 static void mcf_uart_update(mcf_uart_state *s)
  66 {
  67     s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT);
  68     if (s->sr & MCF_UART_TxRDY)
  69         s->isr |= MCF_UART_TxINT;
  70     if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ)
  71                   ? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0)
  72         s->isr |= MCF_UART_RxINT;
  73
  74     qemu_set_irq(s->irq, (s->isr & s->imr) != 0);
  75 }
  76
  77 uint64_t mcf_uart_read(void *opaque, hwaddr addr,
  78                        unsigned size)
  79 {
  80     mcf_uart_state *s = (mcf_uart_state *)opaque;
  81     switch (addr & 0x3f) {
  82     case 0x00:
  83         return s->mr[s->current_mr];
  84     case 0x04:
  85         return s->sr;
  86     case 0x0c:
  87         {
  88             uint8_t val;
  89             int i;
  90
  91             if (s->fifo_len == 0)
  92                 return 0;
  93
  94             val = s->fifo[0];
  95             s->fifo_len--;
  96             for (i = 0; i < s->fifo_len; i++)
  97                 s->fifo[i] = s->fifo[i + 1];
  98             s->sr &= ~MCF_UART_FFULL;
  99             if (s->fifo_len == 0)
 100                 s->sr &= ~MCF_UART_RxRDY;
 101             mcf_uart_update(s);
 102             qemu_chr_fe_accept_input(&s->chr);
 103             return val;
 104         }
 105     case 0x10:
 106         /* TODO: Implement IPCR.  */
 107         return 0;
 108     case 0x14:
 109         return s->isr;
 110     case 0x18:
 111         return s->bg1;
 112     case 0x1c:
 113         return s->bg2;
 114     default:
 115         return 0;
 116     }
 117 }
 118
 119 /* Update TxRDY flag and set data if present and enabled.  */
 120 static void mcf_uart_do_tx(mcf_uart_state *s)
 121 {
 122     if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) {
 123         /* XXX this blocks entire thread. Rewrite to use
 124          * qemu_chr_fe_write and background I/O callbacks */
 125         qemu_chr_fe_write_all(&s->chr, (unsigned char *)&s->tb, 1);
 126         s->sr |= MCF_UART_TxEMP;
 127     }
 128     if (s->tx_enabled) {
 129         s->sr |= MCF_UART_TxRDY;
 130     } else {
 131         s->sr &= ~MCF_UART_TxRDY;
 132     }
 133 }
 134
 135 static void mcf_do_command(mcf_uart_state *s, uint8_t cmd)
 136 {
 137     /* Misc command.  */
 138     switch ((cmd >> 4) & 7) {
 139     case 0: /* No-op.  */
 140         break;
 141     case 1: /* Reset mode register pointer.  */
 142         s->current_mr = 0;
 143         break;
 144     case 2: /* Reset receiver.  */
 145         s->rx_enabled = 0;
 146         s->fifo_len = 0;
 147         s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL);
 148         break;
 149     case 3: /* Reset transmitter.  */
 150         s->tx_enabled = 0;
 151         s->sr |= MCF_UART_TxEMP;
 152         s->sr &= ~MCF_UART_TxRDY;
 153         break;
 154     case 4: /* Reset error status.  */
 155         break;
 156     case 5: /* Reset break-change interrupt.  */
 157         s->isr &= ~MCF_UART_DBINT;
 158         break;
 159     case 6: /* Start break.  */
 160     case 7: /* Stop break.  */
 161         break;
 162     }
 163
 164     /* Transmitter command.  */
 165     switch ((cmd >> 2) & 3) {
 166     case 0: /* No-op.  */
 167         break;
 168     case 1: /* Enable.  */
 169         s->tx_enabled = 1;
 170         mcf_uart_do_tx(s);
 171         break;
 172     case 2: /* Disable.  */
 173         s->tx_enabled = 0;
 174         mcf_uart_do_tx(s);
 175         break;
 176     case 3: /* Reserved.  */
 177         fprintf(stderr, "mcf_uart: Bad TX command\n");
 178         break;
 179     }
 180
 181     /* Receiver command.  */
 182     switch (cmd & 3) {
 183     case 0: /* No-op.  */
 184         break;
 185     case 1: /* Enable.  */
 186         s->rx_enabled = 1;
 187         break;
 188     case 2:
 189         s->rx_enabled = 0;
 190         break;
 191     case 3: /* Reserved.  */
 192         fprintf(stderr, "mcf_uart: Bad RX command\n");
 193         break;
 194     }
 195 }
 196
 197 void mcf_uart_write(void *opaque, hwaddr addr,
 198                     uint64_t val, unsigned size)
 199 {
 200     mcf_uart_state *s = (mcf_uart_state *)opaque;
 201     switch (addr & 0x3f) {
 202     case 0x00:
 203         s->mr[s->current_mr] = val;
 204         s->current_mr = 1;
 205         break;
 206     case 0x04:
 207         /* CSR is ignored.  */
 208         break;
 209     case 0x08: /* Command Register.  */
 210         mcf_do_command(s, val);
 211         break;
 212     case 0x0c: /* Transmit Buffer.  */
 213         s->sr &= ~MCF_UART_TxEMP;
 214         s->tb = val;
 215         mcf_uart_do_tx(s);
 216         break;
 217     case 0x10:
 218         /* ACR is ignored.  */
 219         break;
 220     case 0x14:
 221         s->imr = val;
 222         break;
 223     default:
 224         break;
 225     }
 226     mcf_uart_update(s);
 227 }
 228
 229 static void mcf_uart_reset(DeviceState *dev)
 230 {
 231     mcf_uart_state *s = MCF_UART(dev);
 232
 233     s->fifo_len = 0;
 234     s->mr[0] = 0;
 235     s->mr[1] = 0;
 236     s->sr = MCF_UART_TxEMP;
 237     s->tx_enabled = 0;
 238     s->rx_enabled = 0;
 239     s->isr = 0;
 240     s->imr = 0;
 241 }
 242
 243 static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data)
 244 {
 245     /* Break events overwrite the last byte if the fifo is full.  */
 246     if (s->fifo_len == 4)
 247         s->fifo_len--;
 248
 249     s->fifo[s->fifo_len] = data;
 250     s->fifo_len++;
 251     s->sr |= MCF_UART_RxRDY;
 252     if (s->fifo_len == 4)
 253         s->sr |= MCF_UART_FFULL;
 254
 255     mcf_uart_update(s);
 256 }
 257
 258 static void mcf_uart_event(void *opaque, int event)
 259 {
 260     mcf_uart_state *s = (mcf_uart_state *)opaque;
 261
 262     switch (event) {
 263     case CHR_EVENT_BREAK:
 264         s->isr |= MCF_UART_DBINT;
 265         mcf_uart_push_byte(s, 0);
 266         break;
 267     default:
 268         break;
 269     }
 270 }
 271
 272 static int mcf_uart_can_receive(void *opaque)
 273 {
 274     mcf_uart_state *s = (mcf_uart_state *)opaque;
 275
 276     return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0;
 277 }
 278
 279 static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size)
 280 {
 281     mcf_uart_state *s = (mcf_uart_state *)opaque;
 282
 283     mcf_uart_push_byte(s, buf[0]);
 284 }
 285
 286 static const MemoryRegionOps mcf_uart_ops = {
 287     .read = mcf_uart_read,
 288     .write = mcf_uart_write,
 289     .endianness = DEVICE_NATIVE_ENDIAN,
 290 };
 291
 292 static void mcf_uart_instance_init(Object *obj)
 293 {
 294     SysBusDevice *dev = SYS_BUS_DEVICE(obj);
 295     mcf_uart_state *s = MCF_UART(dev);
 296
 297     memory_region_init_io(&s->iomem, obj, &mcf_uart_ops, s, "uart", 0x40);
 298     sysbus_init_mmio(dev, &s->iomem);
 299
 300     sysbus_init_irq(dev, &s->irq);
 301 }
 302
 303 static void mcf_uart_realize(DeviceState *dev, Error **errp)
 304 {
 305     mcf_uart_state *s = MCF_UART(dev);
 306
 307     qemu_chr_fe_set_handlers(&s->chr, mcf_uart_can_receive, mcf_uart_receive,
 308                              mcf_uart_event, NULL, s, NULL, true);
 309 }
 310
 311 static Property mcf_uart_properties[] = {
 312     DEFINE_PROP_CHR("chardev", mcf_uart_state, chr),
 313     DEFINE_PROP_END_OF_LIST(),
 314 };
 315
 316 static void mcf_uart_class_init(ObjectClass *oc, void *data)
 317 {
 318     DeviceClass *dc = DEVICE_CLASS(oc);
 319
 320     dc->realize = mcf_uart_realize;
 321     dc->reset = mcf_uart_reset;
 322     dc->props = mcf_uart_properties;
 323     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 324 }
 325
 326 static const TypeInfo mcf_uart_info = {
 327     .name          = TYPE_MCF_UART,
 328     .parent        = TYPE_SYS_BUS_DEVICE,
 329     .instance_size = sizeof(mcf_uart_state),
 330     .instance_init = mcf_uart_instance_init,
 331     .class_init    = mcf_uart_class_init,
 332 };
 333
 334 static void mcf_uart_register(void)
 335 {
 336     type_register_static(&mcf_uart_info);
 337 }
 338
 339 type_init(mcf_uart_register)
 340
 341 void *mcf_uart_init(qemu_irq irq, Chardev *chrdrv)
 342 {
 343     DeviceState  *dev;
 344
 345     dev = qdev_create(NULL, TYPE_MCF_UART);
 346     if (chrdrv) {
 347         qdev_prop_set_chr(dev, "chardev", chrdrv);
 348     }
 349     qdev_init_nofail(dev);
 350
 351     sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, irq);
 352
 353     return dev;
 354 }
 355
 356 void mcf_uart_mm_init(hwaddr base, qemu_irq irq, Chardev *chrdrv)
 357 {
 358     DeviceState  *dev;
 359
 360     dev = mcf_uart_init(irq, chrdrv);
 361     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, base);
 362 }