hw/char/serial.c

   1 /*
   2  * QEMU 16550A UART emulation
   3  *
   4  * Copyright (c) 2003-2004 Fabrice Bellard
   5  * Copyright (c) 2008 Citrix Systems, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "qemu/osdep.h"
  27 #include "hw/char/serial.h"
  28 #include "sysemu/char.h"
  29 #include "qapi/error.h"
  30 #include "qemu/timer.h"
  31 #include "exec/address-spaces.h"
  32 #include "qemu/error-report.h"
  33
  34 //#define DEBUG_SERIAL
  35
  36 #define UART_LCR_DLAB   0x80    /* Divisor latch access bit */
  37
  38 #define UART_IER_MSI    0x08    /* Enable Modem status interrupt */
  39 #define UART_IER_RLSI   0x04    /* Enable receiver line status interrupt */
  40 #define UART_IER_THRI   0x02    /* Enable Transmitter holding register int. */
  41 #define UART_IER_RDI    0x01    /* Enable receiver data interrupt */
  42
  43 #define UART_IIR_NO_INT 0x01    /* No interrupts pending */
  44 #define UART_IIR_ID     0x06    /* Mask for the interrupt ID */
  45
  46 #define UART_IIR_MSI    0x00    /* Modem status interrupt */
  47 #define UART_IIR_THRI   0x02    /* Transmitter holding register empty */
  48 #define UART_IIR_RDI    0x04    /* Receiver data interrupt */
  49 #define UART_IIR_RLSI   0x06    /* Receiver line status interrupt */
  50 #define UART_IIR_CTI    0x0C    /* Character Timeout Indication */
  51
  52 #define UART_IIR_FENF   0x80    /* Fifo enabled, but not functionning */
  53 #define UART_IIR_FE     0xC0    /* Fifo enabled */
  54
  55 /*
  56  * These are the definitions for the Modem Control Register
  57  */
  58 #define UART_MCR_LOOP   0x10    /* Enable loopback test mode */
  59 #define UART_MCR_OUT2   0x08    /* Out2 complement */
  60 #define UART_MCR_OUT1   0x04    /* Out1 complement */
  61 #define UART_MCR_RTS    0x02    /* RTS complement */
  62 #define UART_MCR_DTR    0x01    /* DTR complement */
  63
  64 /*
  65  * These are the definitions for the Modem Status Register
  66  */
  67 #define UART_MSR_DCD    0x80    /* Data Carrier Detect */
  68 #define UART_MSR_RI     0x40    /* Ring Indicator */
  69 #define UART_MSR_DSR    0x20    /* Data Set Ready */
  70 #define UART_MSR_CTS    0x10    /* Clear to Send */
  71 #define UART_MSR_DDCD   0x08    /* Delta DCD */
  72 #define UART_MSR_TERI   0x04    /* Trailing edge ring indicator */
  73 #define UART_MSR_DDSR   0x02    /* Delta DSR */
  74 #define UART_MSR_DCTS   0x01    /* Delta CTS */
  75 #define UART_MSR_ANY_DELTA 0x0F /* Any of the delta bits! */
  76
  77 #define UART_LSR_TEMT   0x40    /* Transmitter empty */
  78 #define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
  79 #define UART_LSR_BI     0x10    /* Break interrupt indicator */
  80 #define UART_LSR_FE     0x08    /* Frame error indicator */
  81 #define UART_LSR_PE     0x04    /* Parity error indicator */
  82 #define UART_LSR_OE     0x02    /* Overrun error indicator */
  83 #define UART_LSR_DR     0x01    /* Receiver data ready */
  84 #define UART_LSR_INT_ANY 0x1E   /* Any of the lsr-interrupt-triggering status bits */
  85
  86 /* Interrupt trigger levels. The byte-counts are for 16550A - in newer UARTs the byte-count for each ITL is higher. */
  87
  88 #define UART_FCR_ITL_1      0x00 /* 1 byte ITL */
  89 #define UART_FCR_ITL_2      0x40 /* 4 bytes ITL */
  90 #define UART_FCR_ITL_3      0x80 /* 8 bytes ITL */
  91 #define UART_FCR_ITL_4      0xC0 /* 14 bytes ITL */
  92
  93 #define UART_FCR_DMS        0x08    /* DMA Mode Select */
  94 #define UART_FCR_XFR        0x04    /* XMIT Fifo Reset */
  95 #define UART_FCR_RFR        0x02    /* RCVR Fifo Reset */
  96 #define UART_FCR_FE         0x01    /* FIFO Enable */
  97
  98 #define MAX_XMIT_RETRY      4
  99
 100 #ifdef DEBUG_SERIAL
 101 #define DPRINTF(fmt, ...) \
 102 do { fprintf(stderr, "serial: " fmt , ## __VA_ARGS__); } while (0)
 103 #else
 104 #define DPRINTF(fmt, ...) \
 105 do {} while (0)
 106 #endif
 107
 108 static void serial_receive1(void *opaque, const uint8_t *buf, int size);
 109 static void serial_xmit(SerialState *s);
 110
 111 static inline void recv_fifo_put(SerialState *s, uint8_t chr)
 112 {
 113     /* Receive overruns do not overwrite FIFO contents. */
 114     if (!fifo8_is_full(&s->recv_fifo)) {
 115         fifo8_push(&s->recv_fifo, chr);
 116     } else {
 117         s->lsr |= UART_LSR_OE;
 118     }
 119 }
 120
 121 static void serial_update_irq(SerialState *s)
 122 {
 123     uint8_t tmp_iir = UART_IIR_NO_INT;
 124
 125     if ((s->ier & UART_IER_RLSI) && (s->lsr & UART_LSR_INT_ANY)) {
 126         tmp_iir = UART_IIR_RLSI;
 127     } else if ((s->ier & UART_IER_RDI) && s->timeout_ipending) {
 128         /* Note that(s->ier & UART_IER_RDI) can mask this interrupt,
 129          * this is not in the specification but is observed on existing
 130          * hardware.  */
 131         tmp_iir = UART_IIR_CTI;
 132     } else if ((s->ier & UART_IER_RDI) && (s->lsr & UART_LSR_DR) &&
 133                (!(s->fcr & UART_FCR_FE) ||
 134                 s->recv_fifo.num >= s->recv_fifo_itl)) {
 135         tmp_iir = UART_IIR_RDI;
 136     } else if ((s->ier & UART_IER_THRI) && s->thr_ipending) {
 137         tmp_iir = UART_IIR_THRI;
 138     } else if ((s->ier & UART_IER_MSI) && (s->msr & UART_MSR_ANY_DELTA)) {
 139         tmp_iir = UART_IIR_MSI;
 140     }
 141
 142     s->iir = tmp_iir | (s->iir & 0xF0);
 143
 144     if (tmp_iir != UART_IIR_NO_INT) {
 145         qemu_irq_raise(s->irq);
 146     } else {
 147         qemu_irq_lower(s->irq);
 148     }
 149 }
 150
 151 static void serial_update_parameters(SerialState *s)
 152 {
 153     int speed, parity, data_bits, stop_bits, frame_size;
 154     QEMUSerialSetParams ssp;
 155
 156     if (s->divider == 0 || s->divider > s->baudbase) {
 157         return;
 158     }
 159
 160     /* Start bit. */
 161     frame_size = 1;
 162     if (s->lcr & 0x08) {
 163         /* Parity bit. */
 164         frame_size++;
 165         if (s->lcr & 0x10)
 166             parity = 'E';
 167         else
 168             parity = 'O';
 169     } else {
 170             parity = 'N';
 171     }
 172     if (s->lcr & 0x04)
 173         stop_bits = 2;
 174     else
 175         stop_bits = 1;
 176
 177     data_bits = (s->lcr & 0x03) + 5;
 178     frame_size += data_bits + stop_bits;
 179     speed = s->baudbase / s->divider;
 180     ssp.speed = speed;
 181     ssp.parity = parity;
 182     ssp.data_bits = data_bits;
 183     ssp.stop_bits = stop_bits;
 184     s->char_transmit_time =  (NANOSECONDS_PER_SECOND / speed) * frame_size;
 185     qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
 186
 187     DPRINTF("speed=%d parity=%c data=%d stop=%d\n",
 188            speed, parity, data_bits, stop_bits);
 189 }
 190
 191 static void serial_update_msl(SerialState *s)
 192 {
 193     uint8_t omsr;
 194     int flags;
 195
 196     timer_del(s->modem_status_poll);
 197
 198     if (qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_GET_TIOCM,
 199                           &flags) == -ENOTSUP) {
 200         s->poll_msl = -1;
 201         return;
 202     }
 203
 204     omsr = s->msr;
 205
 206     s->msr = (flags & CHR_TIOCM_CTS) ? s->msr | UART_MSR_CTS : s->msr & ~UART_MSR_CTS;
 207     s->msr = (flags & CHR_TIOCM_DSR) ? s->msr | UART_MSR_DSR : s->msr & ~UART_MSR_DSR;
 208     s->msr = (flags & CHR_TIOCM_CAR) ? s->msr | UART_MSR_DCD : s->msr & ~UART_MSR_DCD;
 209     s->msr = (flags & CHR_TIOCM_RI) ? s->msr | UART_MSR_RI : s->msr & ~UART_MSR_RI;
 210
 211     if (s->msr != omsr) {
 212          /* Set delta bits */
 213          s->msr = s->msr | ((s->msr >> 4) ^ (omsr >> 4));
 214          /* UART_MSR_TERI only if change was from 1 -> 0 */
 215          if ((s->msr & UART_MSR_TERI) && !(omsr & UART_MSR_RI))
 216              s->msr &= ~UART_MSR_TERI;
 217          serial_update_irq(s);
 218     }
 219
 220     /* The real 16550A apparently has a 250ns response latency to line status changes.
 221        We'll be lazy and poll only every 10ms, and only poll it at all if MSI interrupts are turned on */
 222
 223     if (s->poll_msl) {
 224         timer_mod(s->modem_status_poll, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
 225                   NANOSECONDS_PER_SECOND / 100);
 226     }
 227 }
 228
 229 static gboolean serial_watch_cb(GIOChannel *chan, GIOCondition cond,
 230                                 void *opaque)
 231 {
 232     SerialState *s = opaque;
 233     s->watch_tag = 0;
 234     serial_xmit(s);
 235     return FALSE;
 236 }
 237
 238 static void serial_xmit(SerialState *s)
 239 {
 240     do {
 241         assert(!(s->lsr & UART_LSR_TEMT));
 242         if (s->tsr_retry == 0) {
 243             assert(!(s->lsr & UART_LSR_THRE));
 244
 245             if (s->fcr & UART_FCR_FE) {
 246                 assert(!fifo8_is_empty(&s->xmit_fifo));
 247                 s->tsr = fifo8_pop(&s->xmit_fifo);
 248                 if (!s->xmit_fifo.num) {
 249                     s->lsr |= UART_LSR_THRE;
 250                 }
 251             } else {
 252                 s->tsr = s->thr;
 253                 s->lsr |= UART_LSR_THRE;
 254             }
 255             if ((s->lsr & UART_LSR_THRE) && !s->thr_ipending) {
 256                 s->thr_ipending = 1;
 257                 serial_update_irq(s);
 258             }
 259         }
 260
 261         if (s->mcr & UART_MCR_LOOP) {
 262             /* in loopback mode, say that we just received a char */
 263             serial_receive1(s, &s->tsr, 1);
 264         } else if (qemu_chr_fe_write(&s->chr, &s->tsr, 1) != 1 &&
 265                    s->tsr_retry < MAX_XMIT_RETRY) {
 266             assert(s->watch_tag == 0);
 267             s->watch_tag =
 268                 qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
 269                                       serial_watch_cb, s);
 270             if (s->watch_tag > 0) {
 271                 s->tsr_retry++;
 272                 return;
 273             }
 274         }
 275         s->tsr_retry = 0;
 276
 277         /* Transmit another byte if it is already available. It is only
 278            possible when FIFO is enabled and not empty. */
 279     } while (!(s->lsr & UART_LSR_THRE));
 280
 281     s->last_xmit_ts = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 282     s->lsr |= UART_LSR_TEMT;
 283 }
 284
 285 /* Setter for FCR.
 286    is_load flag means, that value is set while loading VM state
 287    and interrupt should not be invoked */
 288 static void serial_write_fcr(SerialState *s, uint8_t val)
 289 {
 290     /* Set fcr - val only has the bits that are supposed to "stick" */
 291     s->fcr = val;
 292
 293     if (val & UART_FCR_FE) {
 294         s->iir |= UART_IIR_FE;
 295         /* Set recv_fifo trigger Level */
 296         switch (val & 0xC0) {
 297         case UART_FCR_ITL_1:
 298             s->recv_fifo_itl = 1;
 299             break;
 300         case UART_FCR_ITL_2:
 301             s->recv_fifo_itl = 4;
 302             break;
 303         case UART_FCR_ITL_3:
 304             s->recv_fifo_itl = 8;
 305             break;
 306         case UART_FCR_ITL_4:
 307             s->recv_fifo_itl = 14;
 308             break;
 309         }
 310     } else {
 311         s->iir &= ~UART_IIR_FE;
 312     }
 313 }
 314
 315 static void serial_ioport_write(void *opaque, hwaddr addr, uint64_t val,
 316                                 unsigned size)
 317 {
 318     SerialState *s = opaque;
 319
 320     addr &= 7;
 321     DPRINTF("write addr=0x%" HWADDR_PRIx " val=0x%" PRIx64 "\n", addr, val);
 322     switch(addr) {
 323     default:
 324     case 0:
 325         if (s->lcr & UART_LCR_DLAB) {
 326             s->divider = (s->divider & 0xff00) | val;
 327             serial_update_parameters(s);
 328         } else {
 329             s->thr = (uint8_t) val;
 330             if(s->fcr & UART_FCR_FE) {
 331                 /* xmit overruns overwrite data, so make space if needed */
 332                 if (fifo8_is_full(&s->xmit_fifo)) {
 333                     fifo8_pop(&s->xmit_fifo);
 334                 }
 335                 fifo8_push(&s->xmit_fifo, s->thr);
 336             }
 337             s->thr_ipending = 0;
 338             s->lsr &= ~UART_LSR_THRE;
 339             s->lsr &= ~UART_LSR_TEMT;
 340             serial_update_irq(s);
 341             if (s->tsr_retry == 0) {
 342                 serial_xmit(s);
 343             }
 344         }
 345         break;
 346     case 1:
 347         if (s->lcr & UART_LCR_DLAB) {
 348             s->divider = (s->divider & 0x00ff) | (val << 8);
 349             serial_update_parameters(s);
 350         } else {
 351             uint8_t changed = (s->ier ^ val) & 0x0f;
 352             s->ier = val & 0x0f;
 353             /* If the backend device is a real serial port, turn polling of the modem
 354              * status lines on physical port on or off depending on UART_IER_MSI state.
 355              */
 356             if ((changed & UART_IER_MSI) && s->poll_msl >= 0) {
 357                 if (s->ier & UART_IER_MSI) {
 358                      s->poll_msl = 1;
 359                      serial_update_msl(s);
 360                 } else {
 361                      timer_del(s->modem_status_poll);
 362                      s->poll_msl = 0;
 363                 }
 364             }
 365
 366             /* Turning on the THRE interrupt on IER can trigger the interrupt
 367              * if LSR.THRE=1, even if it had been masked before by reading IIR.
 368              * This is not in the datasheet, but Windows relies on it.  It is
 369              * unclear if THRE has to be resampled every time THRI becomes
 370              * 1, or only on the rising edge.  Bochs does the latter, and Windows
 371              * always toggles IER to all zeroes and back to all ones, so do the
 372              * same.
 373              *
 374              * If IER.THRI is zero, thr_ipending is not used.  Set it to zero
 375              * so that the thr_ipending subsection is not migrated.
 376              */
 377             if (changed & UART_IER_THRI) {
 378                 if ((s->ier & UART_IER_THRI) && (s->lsr & UART_LSR_THRE)) {
 379                     s->thr_ipending = 1;
 380                 } else {
 381                     s->thr_ipending = 0;
 382                 }
 383             }
 384
 385             if (changed) {
 386                 serial_update_irq(s);
 387             }
 388         }
 389         break;
 390     case 2:
 391         /* Did the enable/disable flag change? If so, make sure FIFOs get flushed */
 392         if ((val ^ s->fcr) & UART_FCR_FE) {
 393             val |= UART_FCR_XFR | UART_FCR_RFR;
 394         }
 395
 396         /* FIFO clear */
 397
 398         if (val & UART_FCR_RFR) {
 399             s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 400             timer_del(s->fifo_timeout_timer);
 401             s->timeout_ipending = 0;
 402             fifo8_reset(&s->recv_fifo);
 403         }
 404
 405         if (val & UART_FCR_XFR) {
 406             s->lsr |= UART_LSR_THRE;
 407             s->thr_ipending = 1;
 408             fifo8_reset(&s->xmit_fifo);
 409         }
 410
 411         serial_write_fcr(s, val & 0xC9);
 412         serial_update_irq(s);
 413         break;
 414     case 3:
 415         {
 416             int break_enable;
 417             s->lcr = val;
 418             serial_update_parameters(s);
 419             break_enable = (val >> 6) & 1;
 420             if (break_enable != s->last_break_enable) {
 421                 s->last_break_enable = break_enable;
 422                 qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
 423                                   &break_enable);
 424             }
 425         }
 426         break;
 427     case 4:
 428         {
 429             int flags;
 430             int old_mcr = s->mcr;
 431             s->mcr = val & 0x1f;
 432             if (val & UART_MCR_LOOP)
 433                 break;
 434
 435             if (s->poll_msl >= 0 && old_mcr != s->mcr) {
 436
 437                 qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_GET_TIOCM, &flags);
 438
 439                 flags &= ~(CHR_TIOCM_RTS | CHR_TIOCM_DTR);
 440
 441                 if (val & UART_MCR_RTS)
 442                     flags |= CHR_TIOCM_RTS;
 443                 if (val & UART_MCR_DTR)
 444                     flags |= CHR_TIOCM_DTR;
 445
 446                 qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_TIOCM, &flags);
 447                 /* Update the modem status after a one-character-send wait-time, since there may be a response
 448                    from the device/computer at the other end of the serial line */
 449                 timer_mod(s->modem_status_poll, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time);
 450             }
 451         }
 452         break;
 453     case 5:
 454         break;
 455     case 6:
 456         break;
 457     case 7:
 458         s->scr = val;
 459         break;
 460     }
 461 }
 462
 463 static uint64_t serial_ioport_read(void *opaque, hwaddr addr, unsigned size)
 464 {
 465     SerialState *s = opaque;
 466     uint32_t ret;
 467
 468     addr &= 7;
 469     switch(addr) {
 470     default:
 471     case 0:
 472         if (s->lcr & UART_LCR_DLAB) {
 473             ret = s->divider & 0xff;
 474         } else {
 475             if(s->fcr & UART_FCR_FE) {
 476                 ret = fifo8_is_empty(&s->recv_fifo) ?
 477                             0 : fifo8_pop(&s->recv_fifo);
 478                 if (s->recv_fifo.num == 0) {
 479                     s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 480                 } else {
 481                     timer_mod(s->fifo_timeout_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time * 4);
 482                 }
 483                 s->timeout_ipending = 0;
 484             } else {
 485                 ret = s->rbr;
 486                 s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 487             }
 488             serial_update_irq(s);
 489             if (!(s->mcr & UART_MCR_LOOP)) {
 490                 /* in loopback mode, don't receive any data */
 491                 qemu_chr_fe_accept_input(&s->chr);
 492             }
 493         }
 494         break;
 495     case 1:
 496         if (s->lcr & UART_LCR_DLAB) {
 497             ret = (s->divider >> 8) & 0xff;
 498         } else {
 499             ret = s->ier;
 500         }
 501         break;
 502     case 2:
 503         ret = s->iir;
 504         if ((ret & UART_IIR_ID) == UART_IIR_THRI) {
 505             s->thr_ipending = 0;
 506             serial_update_irq(s);
 507         }
 508         break;
 509     case 3:
 510         ret = s->lcr;
 511         break;
 512     case 4:
 513         ret = s->mcr;
 514         break;
 515     case 5:
 516         ret = s->lsr;
 517         /* Clear break and overrun interrupts */
 518         if (s->lsr & (UART_LSR_BI|UART_LSR_OE)) {
 519             s->lsr &= ~(UART_LSR_BI|UART_LSR_OE);
 520             serial_update_irq(s);
 521         }
 522         break;
 523     case 6:
 524         if (s->mcr & UART_MCR_LOOP) {
 525             /* in loopback, the modem output pins are connected to the
 526                inputs */
 527             ret = (s->mcr & 0x0c) << 4;
 528             ret |= (s->mcr & 0x02) << 3;
 529             ret |= (s->mcr & 0x01) << 5;
 530         } else {
 531             if (s->poll_msl >= 0)
 532                 serial_update_msl(s);
 533             ret = s->msr;
 534             /* Clear delta bits & msr int after read, if they were set */
 535             if (s->msr & UART_MSR_ANY_DELTA) {
 536                 s->msr &= 0xF0;
 537                 serial_update_irq(s);
 538             }
 539         }
 540         break;
 541     case 7:
 542         ret = s->scr;
 543         break;
 544     }
 545     DPRINTF("read addr=0x%" HWADDR_PRIx " val=0x%02x\n", addr, ret);
 546     return ret;
 547 }
 548
 549 static int serial_can_receive(SerialState *s)
 550 {
 551     if(s->fcr & UART_FCR_FE) {
 552         if (s->recv_fifo.num < UART_FIFO_LENGTH) {
 553             /*
 554              * Advertise (fifo.itl - fifo.count) bytes when count < ITL, and 1
 555              * if above. If UART_FIFO_LENGTH - fifo.count is advertised the
 556              * effect will be to almost always fill the fifo completely before
 557              * the guest has a chance to respond, effectively overriding the ITL
 558              * that the guest has set.
 559              */
 560             return (s->recv_fifo.num <= s->recv_fifo_itl) ?
 561                         s->recv_fifo_itl - s->recv_fifo.num : 1;
 562         } else {
 563             return 0;
 564         }
 565     } else {
 566         return !(s->lsr & UART_LSR_DR);
 567     }
 568 }
 569
 570 static void serial_receive_break(SerialState *s)
 571 {
 572     s->rbr = 0;
 573     /* When the LSR_DR is set a null byte is pushed into the fifo */
 574     recv_fifo_put(s, '\0');
 575     s->lsr |= UART_LSR_BI | UART_LSR_DR;
 576     serial_update_irq(s);
 577 }
 578
 579 /* There's data in recv_fifo and s->rbr has not been read for 4 char transmit times */
 580 static void fifo_timeout_int (void *opaque) {
 581     SerialState *s = opaque;
 582     if (s->recv_fifo.num) {
 583         s->timeout_ipending = 1;
 584         serial_update_irq(s);
 585     }
 586 }
 587
 588 static int serial_can_receive1(void *opaque)
 589 {
 590     SerialState *s = opaque;
 591     return serial_can_receive(s);
 592 }
 593
 594 static void serial_receive1(void *opaque, const uint8_t *buf, int size)
 595 {
 596     SerialState *s = opaque;
 597
 598     if (s->wakeup) {
 599         qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 600     }
 601     if(s->fcr & UART_FCR_FE) {
 602         int i;
 603         for (i = 0; i < size; i++) {
 604             recv_fifo_put(s, buf[i]);
 605         }
 606         s->lsr |= UART_LSR_DR;
 607         /* call the timeout receive callback in 4 char transmit time */
 608         timer_mod(s->fifo_timeout_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time * 4);
 609     } else {
 610         if (s->lsr & UART_LSR_DR)
 611             s->lsr |= UART_LSR_OE;
 612         s->rbr = buf[0];
 613         s->lsr |= UART_LSR_DR;
 614     }
 615     serial_update_irq(s);
 616 }
 617
 618 static void serial_event(void *opaque, int event)
 619 {
 620     SerialState *s = opaque;
 621     DPRINTF("event %x\n", event);
 622     if (event == CHR_EVENT_BREAK)
 623         serial_receive_break(s);
 624 }
 625
 626 static void serial_pre_save(void *opaque)
 627 {
 628     SerialState *s = opaque;
 629     s->fcr_vmstate = s->fcr;
 630 }
 631
 632 static int serial_pre_load(void *opaque)
 633 {
 634     SerialState *s = opaque;
 635     s->thr_ipending = -1;
 636     s->poll_msl = -1;
 637     return 0;
 638 }
 639
 640 static int serial_post_load(void *opaque, int version_id)
 641 {
 642     SerialState *s = opaque;
 643
 644     if (version_id < 3) {
 645         s->fcr_vmstate = 0;
 646     }
 647     if (s->thr_ipending == -1) {
 648         s->thr_ipending = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
 649     }
 650
 651     if (s->tsr_retry > 0) {
 652         /* tsr_retry > 0 implies LSR.TEMT = 0 (transmitter not empty).  */
 653         if (s->lsr & UART_LSR_TEMT) {
 654             error_report("inconsistent state in serial device "
 655                          "(tsr empty, tsr_retry=%d", s->tsr_retry);
 656             return -1;
 657         }
 658
 659         if (s->tsr_retry > MAX_XMIT_RETRY) {
 660             s->tsr_retry = MAX_XMIT_RETRY;
 661         }
 662
 663         assert(s->watch_tag == 0);
 664         s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
 665                                              serial_watch_cb, s);
 666     } else {
 667         /* tsr_retry == 0 implies LSR.TEMT = 1 (transmitter empty).  */
 668         if (!(s->lsr & UART_LSR_TEMT)) {
 669             error_report("inconsistent state in serial device "
 670                          "(tsr not empty, tsr_retry=0");
 671             return -1;
 672         }
 673     }
 674
 675     s->last_break_enable = (s->lcr >> 6) & 1;
 676     /* Initialize fcr via setter to perform essential side-effects */
 677     serial_write_fcr(s, s->fcr_vmstate);
 678     serial_update_parameters(s);
 679     return 0;
 680 }
 681
 682 static bool serial_thr_ipending_needed(void *opaque)
 683 {
 684     SerialState *s = opaque;
 685
 686     if (s->ier & UART_IER_THRI) {
 687         bool expected_value = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
 688         return s->thr_ipending != expected_value;
 689     } else {
 690         /* LSR.THRE will be sampled again when the interrupt is
 691          * enabled.  thr_ipending is not used in this case, do
 692          * not migrate it.
 693          */
 694         return false;
 695     }
 696 }
 697
 698 static const VMStateDescription vmstate_serial_thr_ipending = {
 699     .name = "serial/thr_ipending",
 700     .version_id = 1,
 701     .minimum_version_id = 1,
 702     .needed = serial_thr_ipending_needed,
 703     .fields = (VMStateField[]) {
 704         VMSTATE_INT32(thr_ipending, SerialState),
 705         VMSTATE_END_OF_LIST()
 706     }
 707 };
 708
 709 static bool serial_tsr_needed(void *opaque)
 710 {
 711     SerialState *s = (SerialState *)opaque;
 712     return s->tsr_retry != 0;
 713 }
 714
 715 static const VMStateDescription vmstate_serial_tsr = {
 716     .name = "serial/tsr",
 717     .version_id = 1,
 718     .minimum_version_id = 1,
 719     .needed = serial_tsr_needed,
 720     .fields = (VMStateField[]) {
 721         VMSTATE_UINT32(tsr_retry, SerialState),
 722         VMSTATE_UINT8(thr, SerialState),
 723         VMSTATE_UINT8(tsr, SerialState),
 724         VMSTATE_END_OF_LIST()
 725     }
 726 };
 727
 728 static bool serial_recv_fifo_needed(void *opaque)
 729 {
 730     SerialState *s = (SerialState *)opaque;
 731     return !fifo8_is_empty(&s->recv_fifo);
 732
 733 }
 734
 735 static const VMStateDescription vmstate_serial_recv_fifo = {
 736     .name = "serial/recv_fifo",
 737     .version_id = 1,
 738     .minimum_version_id = 1,
 739     .needed = serial_recv_fifo_needed,
 740     .fields = (VMStateField[]) {
 741         VMSTATE_STRUCT(recv_fifo, SerialState, 1, vmstate_fifo8, Fifo8),
 742         VMSTATE_END_OF_LIST()
 743     }
 744 };
 745
 746 static bool serial_xmit_fifo_needed(void *opaque)
 747 {
 748     SerialState *s = (SerialState *)opaque;
 749     return !fifo8_is_empty(&s->xmit_fifo);
 750 }
 751
 752 static const VMStateDescription vmstate_serial_xmit_fifo = {
 753     .name = "serial/xmit_fifo",
 754     .version_id = 1,
 755     .minimum_version_id = 1,
 756     .needed = serial_xmit_fifo_needed,
 757     .fields = (VMStateField[]) {
 758         VMSTATE_STRUCT(xmit_fifo, SerialState, 1, vmstate_fifo8, Fifo8),
 759         VMSTATE_END_OF_LIST()
 760     }
 761 };
 762
 763 static bool serial_fifo_timeout_timer_needed(void *opaque)
 764 {
 765     SerialState *s = (SerialState *)opaque;
 766     return timer_pending(s->fifo_timeout_timer);
 767 }
 768
 769 static const VMStateDescription vmstate_serial_fifo_timeout_timer = {
 770     .name = "serial/fifo_timeout_timer",
 771     .version_id = 1,
 772     .minimum_version_id = 1,
 773     .needed = serial_fifo_timeout_timer_needed,
 774     .fields = (VMStateField[]) {
 775         VMSTATE_TIMER_PTR(fifo_timeout_timer, SerialState),
 776         VMSTATE_END_OF_LIST()
 777     }
 778 };
 779
 780 static bool serial_timeout_ipending_needed(void *opaque)
 781 {
 782     SerialState *s = (SerialState *)opaque;
 783     return s->timeout_ipending != 0;
 784 }
 785
 786 static const VMStateDescription vmstate_serial_timeout_ipending = {
 787     .name = "serial/timeout_ipending",
 788     .version_id = 1,
 789     .minimum_version_id = 1,
 790     .needed = serial_timeout_ipending_needed,
 791     .fields = (VMStateField[]) {
 792         VMSTATE_INT32(timeout_ipending, SerialState),
 793         VMSTATE_END_OF_LIST()
 794     }
 795 };
 796
 797 static bool serial_poll_needed(void *opaque)
 798 {
 799     SerialState *s = (SerialState *)opaque;
 800     return s->poll_msl >= 0;
 801 }
 802
 803 static const VMStateDescription vmstate_serial_poll = {
 804     .name = "serial/poll",
 805     .version_id = 1,
 806     .needed = serial_poll_needed,
 807     .minimum_version_id = 1,
 808     .fields = (VMStateField[]) {
 809         VMSTATE_INT32(poll_msl, SerialState),
 810         VMSTATE_TIMER_PTR(modem_status_poll, SerialState),
 811         VMSTATE_END_OF_LIST()
 812     }
 813 };
 814
 815 const VMStateDescription vmstate_serial = {
 816     .name = "serial",
 817     .version_id = 3,
 818     .minimum_version_id = 2,
 819     .pre_save = serial_pre_save,
 820     .pre_load = serial_pre_load,
 821     .post_load = serial_post_load,
 822     .fields = (VMStateField[]) {
 823         VMSTATE_UINT16_V(divider, SerialState, 2),
 824         VMSTATE_UINT8(rbr, SerialState),
 825         VMSTATE_UINT8(ier, SerialState),
 826         VMSTATE_UINT8(iir, SerialState),
 827         VMSTATE_UINT8(lcr, SerialState),
 828         VMSTATE_UINT8(mcr, SerialState),
 829         VMSTATE_UINT8(lsr, SerialState),
 830         VMSTATE_UINT8(msr, SerialState),
 831         VMSTATE_UINT8(scr, SerialState),
 832         VMSTATE_UINT8_V(fcr_vmstate, SerialState, 3),
 833         VMSTATE_END_OF_LIST()
 834     },
 835     .subsections = (const VMStateDescription*[]) {
 836         &vmstate_serial_thr_ipending,
 837         &vmstate_serial_tsr,
 838         &vmstate_serial_recv_fifo,
 839         &vmstate_serial_xmit_fifo,
 840         &vmstate_serial_fifo_timeout_timer,
 841         &vmstate_serial_timeout_ipending,
 842         &vmstate_serial_poll,
 843         NULL
 844     }
 845 };
 846
 847 static void serial_reset(void *opaque)
 848 {
 849     SerialState *s = opaque;
 850
 851     if (s->watch_tag > 0) {
 852         g_source_remove(s->watch_tag);
 853         s->watch_tag = 0;
 854     }
 855
 856     s->rbr = 0;
 857     s->ier = 0;
 858     s->iir = UART_IIR_NO_INT;
 859     s->lcr = 0;
 860     s->lsr = UART_LSR_TEMT | UART_LSR_THRE;
 861     s->msr = UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS;
 862     /* Default to 9600 baud, 1 start bit, 8 data bits, 1 stop bit, no parity. */
 863     s->divider = 0x0C;
 864     s->mcr = UART_MCR_OUT2;
 865     s->scr = 0;
 866     s->tsr_retry = 0;
 867     s->char_transmit_time = (NANOSECONDS_PER_SECOND / 9600) * 10;
 868     s->poll_msl = 0;
 869
 870     s->timeout_ipending = 0;
 871     timer_del(s->fifo_timeout_timer);
 872     timer_del(s->modem_status_poll);
 873
 874     fifo8_reset(&s->recv_fifo);
 875     fifo8_reset(&s->xmit_fifo);
 876
 877     s->last_xmit_ts = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 878
 879     s->thr_ipending = 0;
 880     s->last_break_enable = 0;
 881     qemu_irq_lower(s->irq);
 882
 883     serial_update_msl(s);
 884     s->msr &= ~UART_MSR_ANY_DELTA;
 885 }
 886
 887 void serial_realize_core(SerialState *s, Error **errp)
 888 {
 889     if (!qemu_chr_fe_get_driver(&s->chr)) {
 890         error_setg(errp, "Can't create serial device, empty char device");
 891         return;
 892     }
 893
 894     s->modem_status_poll = timer_new_ns(QEMU_CLOCK_VIRTUAL, (QEMUTimerCB *) serial_update_msl, s);
 895
 896     s->fifo_timeout_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, (QEMUTimerCB *) fifo_timeout_int, s);
 897     qemu_register_reset(serial_reset, s);
 898
 899     qemu_chr_fe_set_handlers(&s->chr, serial_can_receive1, serial_receive1,
 900                              serial_event, s, NULL, true);
 901     fifo8_create(&s->recv_fifo, UART_FIFO_LENGTH);
 902     fifo8_create(&s->xmit_fifo, UART_FIFO_LENGTH);
 903     serial_reset(s);
 904 }
 905
 906 void serial_exit_core(SerialState *s)
 907 {
 908     qemu_chr_fe_deinit(&s->chr);
 909
 910     timer_del(s->modem_status_poll);
 911     timer_free(s->modem_status_poll);
 912
 913     timer_del(s->fifo_timeout_timer);
 914     timer_free(s->fifo_timeout_timer);
 915
 916     fifo8_destroy(&s->recv_fifo);
 917     fifo8_destroy(&s->xmit_fifo);
 918
 919     qemu_unregister_reset(serial_reset, s);
 920 }
 921
 922 /* Change the main reference oscillator frequency. */
 923 void serial_set_frequency(SerialState *s, uint32_t frequency)
 924 {
 925     s->baudbase = frequency;
 926     serial_update_parameters(s);
 927 }
 928
 929 const MemoryRegionOps serial_io_ops = {
 930     .read = serial_ioport_read,
 931     .write = serial_ioport_write,
 932     .impl = {
 933         .min_access_size = 1,
 934         .max_access_size = 1,
 935     },
 936     .endianness = DEVICE_LITTLE_ENDIAN,
 937 };
 938
 939 SerialState *serial_init(int base, qemu_irq irq, int baudbase,
 940                          Chardev *chr, MemoryRegion *system_io)
 941 {
 942     SerialState *s;
 943
 944     s = g_malloc0(sizeof(SerialState));
 945
 946     s->irq = irq;
 947     s->baudbase = baudbase;
 948     qemu_chr_fe_init(&s->chr, chr, &error_abort);
 949     serial_realize_core(s, &error_fatal);
 950
 951     vmstate_register(NULL, base, &vmstate_serial, s);
 952
 953     memory_region_init_io(&s->io, NULL, &serial_io_ops, s, "serial", 8);
 954     memory_region_add_subregion(system_io, base, &s->io);
 955
 956     return s;
 957 }
 958
 959 /* Memory mapped interface */
 960 static uint64_t serial_mm_read(void *opaque, hwaddr addr,
 961                                unsigned size)
 962 {
 963     SerialState *s = opaque;
 964     return serial_ioport_read(s, addr >> s->it_shift, 1);
 965 }
 966
 967 static void serial_mm_write(void *opaque, hwaddr addr,
 968                             uint64_t value, unsigned size)
 969 {
 970     SerialState *s = opaque;
 971     value &= ~0u >> (32 - (size * 8));
 972     serial_ioport_write(s, addr >> s->it_shift, value, 1);
 973 }
 974
 975 static const MemoryRegionOps serial_mm_ops[3] = {
 976     [DEVICE_NATIVE_ENDIAN] = {
 977         .read = serial_mm_read,
 978         .write = serial_mm_write,
 979         .endianness = DEVICE_NATIVE_ENDIAN,
 980     },
 981     [DEVICE_LITTLE_ENDIAN] = {
 982         .read = serial_mm_read,
 983         .write = serial_mm_write,
 984         .endianness = DEVICE_LITTLE_ENDIAN,
 985     },
 986     [DEVICE_BIG_ENDIAN] = {
 987         .read = serial_mm_read,
 988         .write = serial_mm_write,
 989         .endianness = DEVICE_BIG_ENDIAN,
 990     },
 991 };
 992
 993 SerialState *serial_mm_init(MemoryRegion *address_space,
 994                             hwaddr base, int it_shift,
 995                             qemu_irq irq, int baudbase,
 996                             Chardev *chr, enum device_endian end)
 997 {
 998     SerialState *s;
 999
1000     s = g_malloc0(sizeof(SerialState));
1001
1002     s->it_shift = it_shift;
1003     s->irq = irq;
1004     s->baudbase = baudbase;
1005     qemu_chr_fe_init(&s->chr, chr, &error_abort);
1006
1007     serial_realize_core(s, &error_fatal);
1008     vmstate_register(NULL, base, &vmstate_serial, s);
1009
1010     memory_region_init_io(&s->io, NULL, &serial_mm_ops[end], s,
1011                           "serial", 8 << it_shift);
1012     memory_region_add_subregion(address_space, base, &s->io);
1013     return s;
1014 }