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/m68k/mcf.h"
  11 #include "sysemu/char.h"
  12 #include "exec/address-spaces.h"
  13 #include "qapi/error.h"
  14
  15 typedef struct {
  16     MemoryRegion iomem;
  17     uint8_t mr[2];
  18     uint8_t sr;
  19     uint8_t isr;
  20     uint8_t imr;
  21     uint8_t bg1;
  22     uint8_t bg2;
  23     uint8_t fifo[4];
  24     uint8_t tb;
  25     int current_mr;
  26     int fifo_len;
  27     int tx_enabled;
  28     int rx_enabled;
  29     qemu_irq irq;
  30     CharBackend chr;
  31 } mcf_uart_state;
  32
  33 /* UART Status Register bits.  */
  34 #define MCF_UART_RxRDY  0x01
  35 #define MCF_UART_FFULL  0x02
  36 #define MCF_UART_TxRDY  0x04
  37 #define MCF_UART_TxEMP  0x08
  38 #define MCF_UART_OE     0x10
  39 #define MCF_UART_PE     0x20
  40 #define MCF_UART_FE     0x40
  41 #define MCF_UART_RB     0x80
  42
  43 /* Interrupt flags.  */
  44 #define MCF_UART_TxINT  0x01
  45 #define MCF_UART_RxINT  0x02
  46 #define MCF_UART_DBINT  0x04
  47 #define MCF_UART_COSINT 0x80
  48
  49 /* UMR1 flags.  */
  50 #define MCF_UART_BC0    0x01
  51 #define MCF_UART_BC1    0x02
  52 #define MCF_UART_PT     0x04
  53 #define MCF_UART_PM0    0x08
  54 #define MCF_UART_PM1    0x10
  55 #define MCF_UART_ERR    0x20
  56 #define MCF_UART_RxIRQ  0x40
  57 #define MCF_UART_RxRTS  0x80
  58
  59 static void mcf_uart_update(mcf_uart_state *s)
  60 {
  61     s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT);
  62     if (s->sr & MCF_UART_TxRDY)
  63         s->isr |= MCF_UART_TxINT;
  64     if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ)
  65                   ? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0)
  66         s->isr |= MCF_UART_RxINT;
  67
  68     qemu_set_irq(s->irq, (s->isr & s->imr) != 0);
  69 }
  70
  71 uint64_t mcf_uart_read(void *opaque, hwaddr addr,
  72                        unsigned size)
  73 {
  74     mcf_uart_state *s = (mcf_uart_state *)opaque;
  75     switch (addr & 0x3f) {
  76     case 0x00:
  77         return s->mr[s->current_mr];
  78     case 0x04:
  79         return s->sr;
  80     case 0x0c:
  81         {
  82             uint8_t val;
  83             int i;
  84
  85             if (s->fifo_len == 0)
  86                 return 0;
  87
  88             val = s->fifo[0];
  89             s->fifo_len--;
  90             for (i = 0; i < s->fifo_len; i++)
  91                 s->fifo[i] = s->fifo[i + 1];
  92             s->sr &= ~MCF_UART_FFULL;
  93             if (s->fifo_len == 0)
  94                 s->sr &= ~MCF_UART_RxRDY;
  95             mcf_uart_update(s);
  96             qemu_chr_fe_accept_input(&s->chr);
  97             return val;
  98         }
  99     case 0x10:
 100         /* TODO: Implement IPCR.  */
 101         return 0;
 102     case 0x14:
 103         return s->isr;
 104     case 0x18:
 105         return s->bg1;
 106     case 0x1c:
 107         return s->bg2;
 108     default:
 109         return 0;
 110     }
 111 }
 112
 113 /* Update TxRDY flag and set data if present and enabled.  */
 114 static void mcf_uart_do_tx(mcf_uart_state *s)
 115 {
 116     if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) {
 117         /* XXX this blocks entire thread. Rewrite to use
 118          * qemu_chr_fe_write and background I/O callbacks */
 119         qemu_chr_fe_write_all(&s->chr, (unsigned char *)&s->tb, 1);
 120         s->sr |= MCF_UART_TxEMP;
 121     }
 122     if (s->tx_enabled) {
 123         s->sr |= MCF_UART_TxRDY;
 124     } else {
 125         s->sr &= ~MCF_UART_TxRDY;
 126     }
 127 }
 128
 129 static void mcf_do_command(mcf_uart_state *s, uint8_t cmd)
 130 {
 131     /* Misc command.  */
 132     switch ((cmd >> 4) & 7) {
 133     case 0: /* No-op.  */
 134         break;
 135     case 1: /* Reset mode register pointer.  */
 136         s->current_mr = 0;
 137         break;
 138     case 2: /* Reset receiver.  */
 139         s->rx_enabled = 0;
 140         s->fifo_len = 0;
 141         s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL);
 142         break;
 143     case 3: /* Reset transmitter.  */
 144         s->tx_enabled = 0;
 145         s->sr |= MCF_UART_TxEMP;
 146         s->sr &= ~MCF_UART_TxRDY;
 147         break;
 148     case 4: /* Reset error status.  */
 149         break;
 150     case 5: /* Reset break-change interrupt.  */
 151         s->isr &= ~MCF_UART_DBINT;
 152         break;
 153     case 6: /* Start break.  */
 154     case 7: /* Stop break.  */
 155         break;
 156     }
 157
 158     /* Transmitter command.  */
 159     switch ((cmd >> 2) & 3) {
 160     case 0: /* No-op.  */
 161         break;
 162     case 1: /* Enable.  */
 163         s->tx_enabled = 1;
 164         mcf_uart_do_tx(s);
 165         break;
 166     case 2: /* Disable.  */
 167         s->tx_enabled = 0;
 168         mcf_uart_do_tx(s);
 169         break;
 170     case 3: /* Reserved.  */
 171         fprintf(stderr, "mcf_uart: Bad TX command\n");
 172         break;
 173     }
 174
 175     /* Receiver command.  */
 176     switch (cmd & 3) {
 177     case 0: /* No-op.  */
 178         break;
 179     case 1: /* Enable.  */
 180         s->rx_enabled = 1;
 181         break;
 182     case 2:
 183         s->rx_enabled = 0;
 184         break;
 185     case 3: /* Reserved.  */
 186         fprintf(stderr, "mcf_uart: Bad RX command\n");
 187         break;
 188     }
 189 }
 190
 191 void mcf_uart_write(void *opaque, hwaddr addr,
 192                     uint64_t val, unsigned size)
 193 {
 194     mcf_uart_state *s = (mcf_uart_state *)opaque;
 195     switch (addr & 0x3f) {
 196     case 0x00:
 197         s->mr[s->current_mr] = val;
 198         s->current_mr = 1;
 199         break;
 200     case 0x04:
 201         /* CSR is ignored.  */
 202         break;
 203     case 0x08: /* Command Register.  */
 204         mcf_do_command(s, val);
 205         break;
 206     case 0x0c: /* Transmit Buffer.  */
 207         s->sr &= ~MCF_UART_TxEMP;
 208         s->tb = val;
 209         mcf_uart_do_tx(s);
 210         break;
 211     case 0x10:
 212         /* ACR is ignored.  */
 213         break;
 214     case 0x14:
 215         s->imr = val;
 216         break;
 217     default:
 218         break;
 219     }
 220     mcf_uart_update(s);
 221 }
 222
 223 static void mcf_uart_reset(mcf_uart_state *s)
 224 {
 225     s->fifo_len = 0;
 226     s->mr[0] = 0;
 227     s->mr[1] = 0;
 228     s->sr = MCF_UART_TxEMP;
 229     s->tx_enabled = 0;
 230     s->rx_enabled = 0;
 231     s->isr = 0;
 232     s->imr = 0;
 233 }
 234
 235 static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data)
 236 {
 237     /* Break events overwrite the last byte if the fifo is full.  */
 238     if (s->fifo_len == 4)
 239         s->fifo_len--;
 240
 241     s->fifo[s->fifo_len] = data;
 242     s->fifo_len++;
 243     s->sr |= MCF_UART_RxRDY;
 244     if (s->fifo_len == 4)
 245         s->sr |= MCF_UART_FFULL;
 246
 247     mcf_uart_update(s);
 248 }
 249
 250 static void mcf_uart_event(void *opaque, int event)
 251 {
 252     mcf_uart_state *s = (mcf_uart_state *)opaque;
 253
 254     switch (event) {
 255     case CHR_EVENT_BREAK:
 256         s->isr |= MCF_UART_DBINT;
 257         mcf_uart_push_byte(s, 0);
 258         break;
 259     default:
 260         break;
 261     }
 262 }
 263
 264 static int mcf_uart_can_receive(void *opaque)
 265 {
 266     mcf_uart_state *s = (mcf_uart_state *)opaque;
 267
 268     return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0;
 269 }
 270
 271 static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size)
 272 {
 273     mcf_uart_state *s = (mcf_uart_state *)opaque;
 274
 275     mcf_uart_push_byte(s, buf[0]);
 276 }
 277
 278 void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
 279 {
 280     mcf_uart_state *s;
 281
 282     s = g_malloc0(sizeof(mcf_uart_state));
 283     s->irq = irq;
 284     if (chr) {
 285         qemu_chr_fe_init(&s->chr, chr, &error_abort);
 286         qemu_chr_fe_set_handlers(&s->chr, mcf_uart_can_receive,
 287                                  mcf_uart_receive, mcf_uart_event,
 288                                  s, NULL, true);
 289     }
 290     mcf_uart_reset(s);
 291     return s;
 292 }
 293
 294 static const MemoryRegionOps mcf_uart_ops = {
 295     .read = mcf_uart_read,
 296     .write = mcf_uart_write,
 297     .endianness = DEVICE_NATIVE_ENDIAN,
 298 };
 299
 300 void mcf_uart_mm_init(MemoryRegion *sysmem,
 301                       hwaddr base,
 302                       qemu_irq irq,
 303                       CharDriverState *chr)
 304 {
 305     mcf_uart_state *s;
 306
 307     s = mcf_uart_init(irq, chr);
 308     memory_region_init_io(&s->iomem, NULL, &mcf_uart_ops, s, "uart", 0x40);
 309     memory_region_add_subregion(sysmem, base, &s->iomem);
 310 }