hw/syborg_serial.c

   1 /*
   2  * Syborg serial port
   3  *
   4  * Copyright (c) 2008 CodeSourcery
   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 "sysbus.h"
  26 #include "qemu-char.h"
  27 #include "syborg.h"
  28
  29 //#define DEBUG_SYBORG_SERIAL
  30
  31 #ifdef DEBUG_SYBORG_SERIAL
  32 #define DPRINTF(fmt, ...) \
  33 do { printf("syborg_serial: " fmt , ##args); } while (0)
  34 #define BADF(fmt, ...) \
  35 do { fprintf(stderr, "syborg_serial: error: " fmt , ## __VA_ARGS__); \
  36     exit(1);} while (0)
  37 #else
  38 #define DPRINTF(fmt, ...) do {} while(0)
  39 #define BADF(fmt, ...) \
  40 do { fprintf(stderr, "syborg_serial: error: " fmt , ## __VA_ARGS__);} while (0)
  41 #endif
  42
  43 enum {
  44     SERIAL_ID           = 0,
  45     SERIAL_DATA         = 1,
  46     SERIAL_FIFO_COUNT   = 2,
  47     SERIAL_INT_ENABLE   = 3,
  48     SERIAL_DMA_TX_ADDR  = 4,
  49     SERIAL_DMA_TX_COUNT = 5, /* triggers dma */
  50     SERIAL_DMA_RX_ADDR  = 6,
  51     SERIAL_DMA_RX_COUNT = 7, /* triggers dma */
  52     SERIAL_FIFO_SIZE    = 8
  53 };
  54
  55 #define SERIAL_INT_FIFO   (1u << 0)
  56 #define SERIAL_INT_DMA_TX (1u << 1)
  57 #define SERIAL_INT_DMA_RX (1u << 2)
  58
  59 typedef struct {
  60     SysBusDevice busdev;
  61     uint32_t int_enable;
  62     int fifo_size;
  63     uint32_t *read_fifo;
  64     int read_pos;
  65     int read_count;
  66     CharDriverState *chr;
  67     qemu_irq irq;
  68     uint32_t dma_tx_ptr;
  69     uint32_t dma_rx_ptr;
  70     uint32_t dma_rx_size;
  71 } SyborgSerialState;
  72
  73 static void syborg_serial_update(SyborgSerialState *s)
  74 {
  75     int level;
  76     level = 0;
  77     if ((s->int_enable & SERIAL_INT_FIFO) && s->read_count)
  78         level = 1;
  79     if (s->int_enable & SERIAL_INT_DMA_TX)
  80         level = 1;
  81     if ((s->int_enable & SERIAL_INT_DMA_RX) && s->dma_rx_size == 0)
  82         level = 1;
  83
  84     qemu_set_irq(s->irq, level);
  85 }
  86
  87 static uint32_t fifo_pop(SyborgSerialState *s)
  88 {
  89     const uint32_t c = s->read_fifo[s->read_pos];
  90     s->read_count--;
  91     s->read_pos++;
  92     if (s->read_pos == s->fifo_size)
  93         s->read_pos = 0;
  94
  95     DPRINTF("FIFO pop %x (%d)\n", c, s->read_count);
  96     return c;
  97 }
  98
  99 static void fifo_push(SyborgSerialState *s, uint32_t new_value)
 100 {
 101     int slot;
 102
 103     DPRINTF("FIFO push %x (%d)\n", new_value, s->read_count);
 104     slot = s->read_pos + s->read_count;
 105     if (slot >= s->fifo_size)
 106           slot -= s->fifo_size;
 107     s->read_fifo[slot] = new_value;
 108     s->read_count++;
 109 }
 110
 111 static void do_dma_tx(SyborgSerialState *s, uint32_t count)
 112 {
 113     unsigned char ch;
 114
 115     if (count == 0)
 116         return;
 117
 118     if (s->chr != NULL) {
 119         /* optimize later. Now, 1 byte per iteration */
 120         while (count--) {
 121             cpu_physical_memory_read(s->dma_tx_ptr, &ch, 1);
 122             qemu_chr_write(s->chr, &ch, 1);
 123             s->dma_tx_ptr++;
 124         }
 125     } else {
 126         s->dma_tx_ptr += count;
 127     }
 128     /* QEMU char backends do not have a nonblocking mode, so we transmit all
 129        the data imediately and the interrupt status will be unchanged.  */
 130 }
 131
 132 /* Initiate RX DMA, and transfer data from the FIFO.  */
 133 static void dma_rx_start(SyborgSerialState *s, uint32_t len)
 134 {
 135     uint32_t dest;
 136     unsigned char ch;
 137
 138     dest = s->dma_rx_ptr;
 139     if (s->read_count < len) {
 140         s->dma_rx_size = len - s->read_count;
 141         len = s->read_count;
 142     } else {
 143         s->dma_rx_size = 0;
 144     }
 145
 146     while (len--) {
 147         ch = fifo_pop(s);
 148         cpu_physical_memory_write(dest, &ch, 1);
 149         dest++;
 150     }
 151     s->dma_rx_ptr = dest;
 152     syborg_serial_update(s);
 153 }
 154
 155 static uint32_t syborg_serial_read(void *opaque, target_phys_addr_t offset)
 156 {
 157     SyborgSerialState *s = (SyborgSerialState *)opaque;
 158     uint32_t c;
 159
 160     offset &= 0xfff;
 161     DPRINTF("read 0x%x\n", (int)offset);
 162     switch(offset >> 2) {
 163     case SERIAL_ID:
 164         return SYBORG_ID_SERIAL;
 165     case SERIAL_DATA:
 166         if (s->read_count > 0)
 167             c = fifo_pop(s);
 168         else
 169             c = -1;
 170         syborg_serial_update(s);
 171         return c;
 172     case SERIAL_FIFO_COUNT:
 173         return s->read_count;
 174     case SERIAL_INT_ENABLE:
 175         return s->int_enable;
 176     case SERIAL_DMA_TX_ADDR:
 177         return s->dma_tx_ptr;
 178     case SERIAL_DMA_TX_COUNT:
 179         return 0;
 180     case SERIAL_DMA_RX_ADDR:
 181         return s->dma_rx_ptr;
 182     case SERIAL_DMA_RX_COUNT:
 183         return s->dma_rx_size;
 184     case SERIAL_FIFO_SIZE:
 185         return s->fifo_size;
 186
 187     default:
 188         cpu_abort(cpu_single_env, "syborg_serial_read: Bad offset %x\n",
 189                   (int)offset);
 190         return 0;
 191     }
 192 }
 193
 194 static void syborg_serial_write(void *opaque, target_phys_addr_t offset,
 195                                 uint32_t value)
 196 {
 197     SyborgSerialState *s = (SyborgSerialState *)opaque;
 198     unsigned char ch;
 199
 200     offset &= 0xfff;
 201     DPRINTF("Write 0x%x=0x%x\n", (int)offset, value);
 202     switch (offset >> 2) {
 203     case SERIAL_DATA:
 204         ch = value;
 205         if (s->chr)
 206             qemu_chr_write(s->chr, &ch, 1);
 207         break;
 208     case SERIAL_INT_ENABLE:
 209         s->int_enable = value;
 210         syborg_serial_update(s);
 211         break;
 212     case SERIAL_DMA_TX_ADDR:
 213         s->dma_tx_ptr = value;
 214         break;
 215     case SERIAL_DMA_TX_COUNT:
 216         do_dma_tx(s, value);
 217         break;
 218     case SERIAL_DMA_RX_ADDR:
 219         /* For safety, writes to this register cancel any pending DMA.  */
 220         s->dma_rx_size = 0;
 221         s->dma_rx_ptr = value;
 222         break;
 223     case SERIAL_DMA_RX_COUNT:
 224         dma_rx_start(s, value);
 225         break;
 226     default:
 227         cpu_abort(cpu_single_env, "syborg_serial_write: Bad offset %x\n",
 228                   (int)offset);
 229         break;
 230     }
 231 }
 232
 233 static int syborg_serial_can_receive(void *opaque)
 234 {
 235     SyborgSerialState *s = (SyborgSerialState *)opaque;
 236
 237     if (s->dma_rx_size)
 238         return s->dma_rx_size;
 239     return s->fifo_size - s->read_count;
 240 }
 241
 242 static void syborg_serial_receive(void *opaque, const uint8_t *buf, int size)
 243 {
 244     SyborgSerialState *s = (SyborgSerialState *)opaque;
 245
 246     if (s->dma_rx_size) {
 247         /* Place it in the DMA buffer.  */
 248         cpu_physical_memory_write(s->dma_rx_ptr, buf, size);
 249         s->dma_rx_size -= size;
 250         s->dma_rx_ptr += size;
 251     } else {
 252         while (size--)
 253             fifo_push(s, *buf);
 254     }
 255
 256     syborg_serial_update(s);
 257 }
 258
 259 static void syborg_serial_event(void *opaque, int event)
 260 {
 261     /* TODO: Report BREAK events?  */
 262 }
 263
 264 static CPUReadMemoryFunc *syborg_serial_readfn[] = {
 265      syborg_serial_read,
 266      syborg_serial_read,
 267      syborg_serial_read
 268 };
 269
 270 static CPUWriteMemoryFunc *syborg_serial_writefn[] = {
 271      syborg_serial_write,
 272      syborg_serial_write,
 273      syborg_serial_write
 274 };
 275
 276 static void syborg_serial_save(QEMUFile *f, void *opaque)
 277 {
 278     SyborgSerialState *s = opaque;
 279     int i;
 280
 281     qemu_put_be32(f, s->fifo_size);
 282     qemu_put_be32(f, s->int_enable);
 283     qemu_put_be32(f, s->read_pos);
 284     qemu_put_be32(f, s->read_count);
 285     qemu_put_be32(f, s->dma_tx_ptr);
 286     qemu_put_be32(f, s->dma_rx_ptr);
 287     qemu_put_be32(f, s->dma_rx_size);
 288     for (i = 0; i < s->fifo_size; i++) {
 289         qemu_put_be32(f, s->read_fifo[i]);
 290     }
 291 }
 292
 293 static int syborg_serial_load(QEMUFile *f, void *opaque, int version_id)
 294 {
 295     SyborgSerialState *s = opaque;
 296     int i;
 297
 298     if (version_id != 1)
 299         return -EINVAL;
 300
 301     i = qemu_get_be32(f);
 302     if (s->fifo_size != i)
 303         return -EINVAL;
 304
 305     s->int_enable = qemu_get_be32(f);
 306     s->read_pos = qemu_get_be32(f);
 307     s->read_count = qemu_get_be32(f);
 308     s->dma_tx_ptr = qemu_get_be32(f);
 309     s->dma_rx_ptr = qemu_get_be32(f);
 310     s->dma_rx_size = qemu_get_be32(f);
 311     for (i = 0; i < s->fifo_size; i++) {
 312         s->read_fifo[i] = qemu_get_be32(f);
 313     }
 314
 315     return 0;
 316 }
 317
 318 static void syborg_serial_init(SysBusDevice *dev)
 319 {
 320     SyborgSerialState *s = FROM_SYSBUS(SyborgSerialState, dev);
 321     int iomemtype;
 322
 323     sysbus_init_irq(dev, &s->irq);
 324     iomemtype = cpu_register_io_memory(0, syborg_serial_readfn,
 325                                        syborg_serial_writefn, s);
 326     sysbus_init_mmio(dev, 0x1000, iomemtype);
 327     s->chr = qdev_init_chardev(&dev->qdev);
 328     if (s->chr) {
 329         qemu_chr_add_handlers(s->chr, syborg_serial_can_receive,
 330                               syborg_serial_receive, syborg_serial_event, s);
 331     }
 332     s->fifo_size = qdev_get_prop_int(&dev->qdev, "fifo-size", 16);
 333     if (s->fifo_size <= 0) {
 334         fprintf(stderr, "syborg_serial: fifo too small\n");
 335         s->fifo_size = 16;
 336     }
 337     s->read_fifo = qemu_mallocz(s->fifo_size * sizeof(s->read_fifo[0]));
 338
 339     register_savevm("syborg_serial", -1, 1,
 340                     syborg_serial_save, syborg_serial_load, s);
 341 }
 342
 343 static void syborg_serial_register_devices(void)
 344 {
 345     sysbus_register_dev("syborg,serial", sizeof(SyborgSerialState),
 346                         syborg_serial_init);
 347 }
 348
 349 device_init(syborg_serial_register_devices)