hw/mcf_uart.c

   1 /*
   2  * ColdFire UART emulation.
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  *
   6  * This code is licenced under the GPL
   7  */
   8 #include "hw.h"
   9 #include "mcf.h"
  10 #include "qemu-char.h"
  11
  12 typedef struct {
  13     uint8_t mr[2];
  14     uint8_t sr;
  15     uint8_t isr;
  16     uint8_t imr;
  17     uint8_t bg1;
  18     uint8_t bg2;
  19     uint8_t fifo[4];
  20     uint8_t tb;
  21     int current_mr;
  22     int fifo_len;
  23     int tx_enabled;
  24     int rx_enabled;
  25     qemu_irq irq;
  26     CharDriverState *chr;
  27 } mcf_uart_state;
  28
  29 /* UART Status Register bits.  */
  30 #define MCF_UART_RxRDY  0x01
  31 #define MCF_UART_FFULL  0x02
  32 #define MCF_UART_TxRDY  0x04
  33 #define MCF_UART_TxEMP  0x08
  34 #define MCF_UART_OE     0x10
  35 #define MCF_UART_PE     0x20
  36 #define MCF_UART_FE     0x40
  37 #define MCF_UART_RB     0x80
  38
  39 /* Interrupt flags.  */
  40 #define MCF_UART_TxINT  0x01
  41 #define MCF_UART_RxINT  0x02
  42 #define MCF_UART_DBINT  0x04
  43 #define MCF_UART_COSINT 0x80
  44
  45 /* UMR1 flags.  */
  46 #define MCF_UART_BC0    0x01
  47 #define MCF_UART_BC1    0x02
  48 #define MCF_UART_PT     0x04
  49 #define MCF_UART_PM0    0x08
  50 #define MCF_UART_PM1    0x10
  51 #define MCF_UART_ERR    0x20
  52 #define MCF_UART_RxIRQ  0x40
  53 #define MCF_UART_RxRTS  0x80
  54
  55 static void mcf_uart_update(mcf_uart_state *s)
  56 {
  57     s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT);
  58     if (s->sr & MCF_UART_TxRDY)
  59         s->isr |= MCF_UART_TxINT;
  60     if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ)
  61                   ? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0)
  62         s->isr |= MCF_UART_RxINT;
  63
  64     qemu_set_irq(s->irq, (s->isr & s->imr) != 0);
  65 }
  66
  67 uint32_t mcf_uart_read(void *opaque, target_phys_addr_t addr)
  68 {
  69     mcf_uart_state *s = (mcf_uart_state *)opaque;
  70     switch (addr & 0x3f) {
  71     case 0x00:
  72         return s->mr[s->current_mr];
  73     case 0x04:
  74         return s->sr;
  75     case 0x0c:
  76         {
  77             uint8_t val;
  78             int i;
  79
  80             if (s->fifo_len == 0)
  81                 return 0;
  82
  83             val = s->fifo[0];
  84             s->fifo_len--;
  85             for (i = 0; i < s->fifo_len; i++)
  86                 s->fifo[i] = s->fifo[i + 1];
  87             s->sr &= ~MCF_UART_FFULL;
  88             if (s->fifo_len == 0)
  89                 s->sr &= ~MCF_UART_RxRDY;
  90             mcf_uart_update(s);
  91             qemu_chr_accept_input(s->chr);
  92             return val;
  93         }
  94     case 0x10:
  95         /* TODO: Implement IPCR.  */
  96         return 0;
  97     case 0x14:
  98         return s->isr;
  99     case 0x18:
 100         return s->bg1;
 101     case 0x1c:
 102         return s->bg2;
 103     default:
 104         return 0;
 105     }
 106 }
 107
 108 /* Update TxRDY flag and set data if present and enabled.  */
 109 static void mcf_uart_do_tx(mcf_uart_state *s)
 110 {
 111     if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) {
 112         if (s->chr)
 113             qemu_chr_write(s->chr, (unsigned char *)&s->tb, 1);
 114         s->sr |= MCF_UART_TxEMP;
 115     }
 116     if (s->tx_enabled) {
 117         s->sr |= MCF_UART_TxRDY;
 118     } else {
 119         s->sr &= ~MCF_UART_TxRDY;
 120     }
 121 }
 122
 123 static void mcf_do_command(mcf_uart_state *s, uint8_t cmd)
 124 {
 125     /* Misc command.  */
 126     switch ((cmd >> 4) & 3) {
 127     case 0: /* No-op.  */
 128         break;
 129     case 1: /* Reset mode register pointer.  */
 130         s->current_mr = 0;
 131         break;
 132     case 2: /* Reset receiver.  */
 133         s->rx_enabled = 0;
 134         s->fifo_len = 0;
 135         s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL);
 136         break;
 137     case 3: /* Reset transmitter.  */
 138         s->tx_enabled = 0;
 139         s->sr |= MCF_UART_TxEMP;
 140         s->sr &= ~MCF_UART_TxRDY;
 141         break;
 142     case 4: /* Reset error status.  */
 143         break;
 144     case 5: /* Reset break-change interrupt.  */
 145         s->isr &= ~MCF_UART_DBINT;
 146         break;
 147     case 6: /* Start break.  */
 148     case 7: /* Stop break.  */
 149         break;
 150     }
 151
 152     /* Transmitter command.  */
 153     switch ((cmd >> 2) & 3) {
 154     case 0: /* No-op.  */
 155         break;
 156     case 1: /* Enable.  */
 157         s->tx_enabled = 1;
 158         mcf_uart_do_tx(s);
 159         break;
 160     case 2: /* Disable.  */
 161         s->tx_enabled = 0;
 162         mcf_uart_do_tx(s);
 163         break;
 164     case 3: /* Reserved.  */
 165         fprintf(stderr, "mcf_uart: Bad TX command\n");
 166         break;
 167     }
 168
 169     /* Receiver command.  */
 170     switch (cmd & 3) {
 171     case 0: /* No-op.  */
 172         break;
 173     case 1: /* Enable.  */
 174         s->rx_enabled = 1;
 175         break;
 176     case 2:
 177         s->rx_enabled = 0;
 178         break;
 179     case 3: /* Reserved.  */
 180         fprintf(stderr, "mcf_uart: Bad RX command\n");
 181         break;
 182     }
 183 }
 184
 185 void mcf_uart_write(void *opaque, target_phys_addr_t addr, uint32_t val)
 186 {
 187     mcf_uart_state *s = (mcf_uart_state *)opaque;
 188     switch (addr & 0x3f) {
 189     case 0x00:
 190         s->mr[s->current_mr] = val;
 191         s->current_mr = 1;
 192         break;
 193     case 0x04:
 194         /* CSR is ignored.  */
 195         break;
 196     case 0x08: /* Command Register.  */
 197         mcf_do_command(s, val);
 198         break;
 199     case 0x0c: /* Transmit Buffer.  */
 200         s->sr &= ~MCF_UART_TxEMP;
 201         s->tb = val;
 202         mcf_uart_do_tx(s);
 203         break;
 204     case 0x10:
 205         /* ACR is ignored.  */
 206         break;
 207     case 0x14:
 208         s->imr = val;
 209         break;
 210     default:
 211         break;
 212     }
 213     mcf_uart_update(s);
 214 }
 215
 216 static void mcf_uart_reset(mcf_uart_state *s)
 217 {
 218     s->fifo_len = 0;
 219     s->mr[0] = 0;
 220     s->mr[1] = 0;
 221     s->sr = MCF_UART_TxEMP;
 222     s->tx_enabled = 0;
 223     s->rx_enabled = 0;
 224     s->isr = 0;
 225     s->imr = 0;
 226 }
 227
 228 static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data)
 229 {
 230     /* Break events overwrite the last byte if the fifo is full.  */
 231     if (s->fifo_len == 4)
 232         s->fifo_len--;
 233
 234     s->fifo[s->fifo_len] = data;
 235     s->fifo_len++;
 236     s->sr |= MCF_UART_RxRDY;
 237     if (s->fifo_len == 4)
 238         s->sr |= MCF_UART_FFULL;
 239
 240     mcf_uart_update(s);
 241 }
 242
 243 static void mcf_uart_event(void *opaque, int event)
 244 {
 245     mcf_uart_state *s = (mcf_uart_state *)opaque;
 246
 247     switch (event) {
 248     case CHR_EVENT_BREAK:
 249         s->isr |= MCF_UART_DBINT;
 250         mcf_uart_push_byte(s, 0);
 251         break;
 252     default:
 253         break;
 254     }
 255 }
 256
 257 static int mcf_uart_can_receive(void *opaque)
 258 {
 259     mcf_uart_state *s = (mcf_uart_state *)opaque;
 260
 261     return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0;
 262 }
 263
 264 static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size)
 265 {
 266     mcf_uart_state *s = (mcf_uart_state *)opaque;
 267
 268     mcf_uart_push_byte(s, buf[0]);
 269 }
 270
 271 void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
 272 {
 273     mcf_uart_state *s;
 274
 275     s = qemu_mallocz(sizeof(mcf_uart_state));
 276     s->chr = chr;
 277     s->irq = irq;
 278     if (chr) {
 279         qemu_chr_add_handlers(chr, mcf_uart_can_receive, mcf_uart_receive,
 280                               mcf_uart_event, s);
 281     }
 282     mcf_uart_reset(s);
 283     return s;
 284 }
 285
 286
 287 static CPUReadMemoryFunc *mcf_uart_readfn[] = {
 288    mcf_uart_read,
 289    mcf_uart_read,
 290    mcf_uart_read
 291 };
 292
 293 static CPUWriteMemoryFunc *mcf_uart_writefn[] = {
 294    mcf_uart_write,
 295    mcf_uart_write,
 296    mcf_uart_write
 297 };
 298
 299 void mcf_uart_mm_init(target_phys_addr_t base, qemu_irq irq,
 300                       CharDriverState *chr)
 301 {
 302     mcf_uart_state *s;
 303     int iomemtype;
 304
 305     s = mcf_uart_init(irq, chr);
 306     iomemtype = cpu_register_io_memory(0, mcf_uart_readfn,
 307                                        mcf_uart_writefn, s);
 308     cpu_register_physical_memory(base, 0x40, iomemtype);
 309 }