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