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 "hw/irq.h"
  29 #include "migration/vmstate.h"
  30 #include "chardev/char-serial.h"
  31 #include "qapi/error.h"
  32 #include "qemu/timer.h"
  33 #include "sysemu/reset.h"
  34 #include "sysemu/runstate.h"
  35 #include "qemu/error-report.h"
  36 #include "trace.h"
  37 #include "hw/qdev-properties.h"
  38
  39 //#define DEBUG_SERIAL
  40
  41 #define UART_LCR_DLAB   0x80    /* Divisor latch access bit */
  42
  43 #define UART_IER_MSI    0x08    /* Enable Modem status interrupt */
  44 #define UART_IER_RLSI   0x04    /* Enable receiver line status interrupt */
  45 #define UART_IER_THRI   0x02    /* Enable Transmitter holding register int. */
  46 #define UART_IER_RDI    0x01    /* Enable receiver data interrupt */
  47
  48 #define UART_IIR_NO_INT 0x01    /* No interrupts pending */
  49 #define UART_IIR_ID     0x06    /* Mask for the interrupt ID */
  50
  51 #define UART_IIR_MSI    0x00    /* Modem status interrupt */
  52 #define UART_IIR_THRI   0x02    /* Transmitter holding register empty */
  53 #define UART_IIR_RDI    0x04    /* Receiver data interrupt */
  54 #define UART_IIR_RLSI   0x06    /* Receiver line status interrupt */
  55 #define UART_IIR_CTI    0x0C    /* Character Timeout Indication */
  56
  57 #define UART_IIR_FENF   0x80    /* Fifo enabled, but not functionning */
  58 #define UART_IIR_FE     0xC0    /* Fifo enabled */
  59
  60 /*
  61  * These are the definitions for the Modem Control Register
  62  */
  63 #define UART_MCR_LOOP   0x10    /* Enable loopback test mode */
  64 #define UART_MCR_OUT2   0x08    /* Out2 complement */
  65 #define UART_MCR_OUT1   0x04    /* Out1 complement */
  66 #define UART_MCR_RTS    0x02    /* RTS complement */
  67 #define UART_MCR_DTR    0x01    /* DTR complement */
  68
  69 /*
  70  * These are the definitions for the Modem Status Register
  71  */
  72 #define UART_MSR_DCD    0x80    /* Data Carrier Detect */
  73 #define UART_MSR_RI     0x40    /* Ring Indicator */
  74 #define UART_MSR_DSR    0x20    /* Data Set Ready */
  75 #define UART_MSR_CTS    0x10    /* Clear to Send */
  76 #define UART_MSR_DDCD   0x08    /* Delta DCD */
  77 #define UART_MSR_TERI   0x04    /* Trailing edge ring indicator */
  78 #define UART_MSR_DDSR   0x02    /* Delta DSR */
  79 #define UART_MSR_DCTS   0x01    /* Delta CTS */
  80 #define UART_MSR_ANY_DELTA 0x0F /* Any of the delta bits! */
  81
  82 #define UART_LSR_TEMT   0x40    /* Transmitter empty */
  83 #define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
  84 #define UART_LSR_BI     0x10    /* Break interrupt indicator */
  85 #define UART_LSR_FE     0x08    /* Frame error indicator */
  86 #define UART_LSR_PE     0x04    /* Parity error indicator */
  87 #define UART_LSR_OE     0x02    /* Overrun error indicator */
  88 #define UART_LSR_DR     0x01    /* Receiver data ready */
  89 #define UART_LSR_INT_ANY 0x1E   /* Any of the lsr-interrupt-triggering status bits */
  90
  91 /* Interrupt trigger levels. The byte-counts are for 16550A - in newer UARTs the byte-count for each ITL is higher. */
  92
  93 #define UART_FCR_ITL_1      0x00 /* 1 byte ITL */
  94 #define UART_FCR_ITL_2      0x40 /* 4 bytes ITL */
  95 #define UART_FCR_ITL_3      0x80 /* 8 bytes ITL */
  96 #define UART_FCR_ITL_4      0xC0 /* 14 bytes ITL */
  97
  98 #define UART_FCR_DMS        0x08    /* DMA Mode Select */
  99 #define UART_FCR_XFR        0x04    /* XMIT Fifo Reset */
 100 #define UART_FCR_RFR        0x02    /* RCVR Fifo Reset */
 101 #define UART_FCR_FE         0x01    /* FIFO Enable */
 102
 103 #define MAX_XMIT_RETRY      4
 104
 105 #ifdef DEBUG_SERIAL
 106 #define DPRINTF(fmt, ...) \
 107 do { fprintf(stderr, "serial: " fmt , ## __VA_ARGS__); } while (0)
 108 #else
 109 #define DPRINTF(fmt, ...) \
 110 do {} while (0)
 111 #endif
 112
 113 static void serial_receive1(void *opaque, const uint8_t *buf, int size);
 114 static void serial_xmit(SerialState *s);
 115
 116 static inline void recv_fifo_put(SerialState *s, uint8_t chr)
 117 {
 118     /* Receive overruns do not overwrite FIFO contents. */
 119     if (!fifo8_is_full(&s->recv_fifo)) {
 120         fifo8_push(&s->recv_fifo, chr);
 121     } else {
 122         s->lsr |= UART_LSR_OE;
 123     }
 124 }
 125
 126 static void serial_update_irq(SerialState *s)
 127 {
 128     uint8_t tmp_iir = UART_IIR_NO_INT;
 129
 130     if ((s->ier & UART_IER_RLSI) && (s->lsr & UART_LSR_INT_ANY)) {
 131         tmp_iir = UART_IIR_RLSI;
 132     } else if ((s->ier & UART_IER_RDI) && s->timeout_ipending) {
 133         /* Note that(s->ier & UART_IER_RDI) can mask this interrupt,
 134          * this is not in the specification but is observed on existing
 135          * hardware.  */
 136         tmp_iir = UART_IIR_CTI;
 137     } else if ((s->ier & UART_IER_RDI) && (s->lsr & UART_LSR_DR) &&
 138                (!(s->fcr & UART_FCR_FE) ||
 139                 s->recv_fifo.num >= s->recv_fifo_itl)) {
 140         tmp_iir = UART_IIR_RDI;
 141     } else if ((s->ier & UART_IER_THRI) && s->thr_ipending) {
 142         tmp_iir = UART_IIR_THRI;
 143     } else if ((s->ier & UART_IER_MSI) && (s->msr & UART_MSR_ANY_DELTA)) {
 144         tmp_iir = UART_IIR_MSI;
 145     }
 146
 147     s->iir = tmp_iir | (s->iir & 0xF0);
 148
 149     if (tmp_iir != UART_IIR_NO_INT) {
 150         qemu_irq_raise(s->irq);
 151     } else {
 152         qemu_irq_lower(s->irq);
 153     }
 154 }
 155
 156 static void serial_update_parameters(SerialState *s)
 157 {
 158     float speed;
 159     int parity, data_bits, stop_bits, frame_size;
 160     QEMUSerialSetParams ssp;
 161
 162     /* Start bit. */
 163     frame_size = 1;
 164     if (s->lcr & 0x08) {
 165         /* Parity bit. */
 166         frame_size++;
 167         if (s->lcr & 0x10)
 168             parity = 'E';
 169         else
 170             parity = 'O';
 171     } else {
 172             parity = 'N';
 173     }
 174     if (s->lcr & 0x04) {
 175         stop_bits = 2;
 176     } else {
 177         stop_bits = 1;
 178     }
 179
 180     data_bits = (s->lcr & 0x03) + 5;
 181     frame_size += data_bits + stop_bits;
 182     /* Zero divisor should give about 3500 baud */
 183     speed = (s->divider == 0) ? 3500 : (float) s->baudbase / s->divider;
 184     ssp.speed = speed;
 185     ssp.parity = parity;
 186     ssp.data_bits = data_bits;
 187     ssp.stop_bits = stop_bits;
 188     s->char_transmit_time =  (NANOSECONDS_PER_SECOND / speed) * frame_size;
 189     qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
 190
 191     DPRINTF("speed=%.2f parity=%c data=%d stop=%d\n",
 192            speed, parity, data_bits, stop_bits);
 193 }
 194
 195 static void serial_update_msl(SerialState *s)
 196 {
 197     uint8_t omsr;
 198     int flags;
 199
 200     timer_del(s->modem_status_poll);
 201
 202     if (qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_GET_TIOCM,
 203                           &flags) == -ENOTSUP) {
 204         s->poll_msl = -1;
 205         return;
 206     }
 207
 208     omsr = s->msr;
 209
 210     s->msr = (flags & CHR_TIOCM_CTS) ? s->msr | UART_MSR_CTS : s->msr & ~UART_MSR_CTS;
 211     s->msr = (flags & CHR_TIOCM_DSR) ? s->msr | UART_MSR_DSR : s->msr & ~UART_MSR_DSR;
 212     s->msr = (flags & CHR_TIOCM_CAR) ? s->msr | UART_MSR_DCD : s->msr & ~UART_MSR_DCD;
 213     s->msr = (flags & CHR_TIOCM_RI) ? s->msr | UART_MSR_RI : s->msr & ~UART_MSR_RI;
 214
 215     if (s->msr != omsr) {
 216          /* Set delta bits */
 217          s->msr = s->msr | ((s->msr >> 4) ^ (omsr >> 4));
 218          /* UART_MSR_TERI only if change was from 1 -> 0 */
 219          if ((s->msr & UART_MSR_TERI) && !(omsr & UART_MSR_RI))
 220              s->msr &= ~UART_MSR_TERI;
 221          serial_update_irq(s);
 222     }
 223
 224     /* The real 16550A apparently has a 250ns response latency to line status changes.
 225        We'll be lazy and poll only every 10ms, and only poll it at all if MSI interrupts are turned on */
 226
 227     if (s->poll_msl) {
 228         timer_mod(s->modem_status_poll, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
 229                   NANOSECONDS_PER_SECOND / 100);
 230     }
 231 }
 232
 233 static gboolean serial_watch_cb(GIOChannel *chan, GIOCondition cond,
 234                                 void *opaque)
 235 {
 236     SerialState *s = opaque;
 237     s->watch_tag = 0;
 238     serial_xmit(s);
 239     return FALSE;
 240 }
 241
 242 static void serial_xmit(SerialState *s)
 243 {
 244     do {
 245         assert(!(s->lsr & UART_LSR_TEMT));
 246         if (s->tsr_retry == 0) {
 247             assert(!(s->lsr & UART_LSR_THRE));
 248
 249             if (s->fcr & UART_FCR_FE) {
 250                 assert(!fifo8_is_empty(&s->xmit_fifo));
 251                 s->tsr = fifo8_pop(&s->xmit_fifo);
 252                 if (!s->xmit_fifo.num) {
 253                     s->lsr |= UART_LSR_THRE;
 254                 }
 255             } else {
 256                 s->tsr = s->thr;
 257                 s->lsr |= UART_LSR_THRE;
 258             }
 259             if ((s->lsr & UART_LSR_THRE) && !s->thr_ipending) {
 260                 s->thr_ipending = 1;
 261                 serial_update_irq(s);
 262             }
 263         }
 264
 265         if (s->mcr & UART_MCR_LOOP) {
 266             /* in loopback mode, say that we just received a char */
 267             serial_receive1(s, &s->tsr, 1);
 268         } else {
 269             int rc = qemu_chr_fe_write(&s->chr, &s->tsr, 1);
 270
 271             if ((rc == 0 ||
 272                  (rc == -1 && errno == EAGAIN)) &&
 273                 s->tsr_retry < MAX_XMIT_RETRY) {
 274                 assert(s->watch_tag == 0);
 275                 s->watch_tag =
 276                     qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
 277                                           serial_watch_cb, s);
 278                 if (s->watch_tag > 0) {
 279                     s->tsr_retry++;
 280                     return;
 281                 }
 282             }
 283         }
 284         s->tsr_retry = 0;
 285
 286         /* Transmit another byte if it is already available. It is only
 287            possible when FIFO is enabled and not empty. */
 288     } while (!(s->lsr & UART_LSR_THRE));
 289
 290     s->last_xmit_ts = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 291     s->lsr |= UART_LSR_TEMT;
 292 }
 293
 294 /* Setter for FCR.
 295    is_load flag means, that value is set while loading VM state
 296    and interrupt should not be invoked */
 297 static void serial_write_fcr(SerialState *s, uint8_t val)
 298 {
 299     /* Set fcr - val only has the bits that are supposed to "stick" */
 300     s->fcr = val;
 301
 302     if (val & UART_FCR_FE) {
 303         s->iir |= UART_IIR_FE;
 304         /* Set recv_fifo trigger Level */
 305         switch (val & 0xC0) {
 306         case UART_FCR_ITL_1:
 307             s->recv_fifo_itl = 1;
 308             break;
 309         case UART_FCR_ITL_2:
 310             s->recv_fifo_itl = 4;
 311             break;
 312         case UART_FCR_ITL_3:
 313             s->recv_fifo_itl = 8;
 314             break;
 315         case UART_FCR_ITL_4:
 316             s->recv_fifo_itl = 14;
 317             break;
 318         }
 319     } else {
 320         s->iir &= ~UART_IIR_FE;
 321     }
 322 }
 323
 324 static void serial_update_tiocm(SerialState *s)
 325 {
 326     int flags;
 327
 328     qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_GET_TIOCM, &flags);
 329
 330     flags &= ~(CHR_TIOCM_RTS | CHR_TIOCM_DTR);
 331
 332     if (s->mcr & UART_MCR_RTS) {
 333         flags |= CHR_TIOCM_RTS;
 334     }
 335     if (s->mcr & UART_MCR_DTR) {
 336         flags |= CHR_TIOCM_DTR;
 337     }
 338
 339     qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_TIOCM, &flags);
 340 }
 341
 342 static void serial_ioport_write(void *opaque, hwaddr addr, uint64_t val,
 343                                 unsigned size)
 344 {
 345     SerialState *s = opaque;
 346
 347     addr &= 7;
 348     trace_serial_ioport_write(addr, val);
 349     switch(addr) {
 350     default:
 351     case 0:
 352         if (s->lcr & UART_LCR_DLAB) {
 353             if (size == 1) {
 354                 s->divider = (s->divider & 0xff00) | val;
 355             } else {
 356                 s->divider = val;
 357             }
 358             serial_update_parameters(s);
 359         } else {
 360             s->thr = (uint8_t) val;
 361             if(s->fcr & UART_FCR_FE) {
 362                 /* xmit overruns overwrite data, so make space if needed */
 363                 if (fifo8_is_full(&s->xmit_fifo)) {
 364                     fifo8_pop(&s->xmit_fifo);
 365                 }
 366                 fifo8_push(&s->xmit_fifo, s->thr);
 367             }
 368             s->thr_ipending = 0;
 369             s->lsr &= ~UART_LSR_THRE;
 370             s->lsr &= ~UART_LSR_TEMT;
 371             serial_update_irq(s);
 372             if (s->tsr_retry == 0) {
 373                 serial_xmit(s);
 374             }
 375         }
 376         break;
 377     case 1:
 378         if (s->lcr & UART_LCR_DLAB) {
 379             s->divider = (s->divider & 0x00ff) | (val << 8);
 380             serial_update_parameters(s);
 381         } else {
 382             uint8_t changed = (s->ier ^ val) & 0x0f;
 383             s->ier = val & 0x0f;
 384             /* If the backend device is a real serial port, turn polling of the modem
 385              * status lines on physical port on or off depending on UART_IER_MSI state.
 386              */
 387             if ((changed & UART_IER_MSI) && s->poll_msl >= 0) {
 388                 if (s->ier & UART_IER_MSI) {
 389                      s->poll_msl = 1;
 390                      serial_update_msl(s);
 391                 } else {
 392                      timer_del(s->modem_status_poll);
 393                      s->poll_msl = 0;
 394                 }
 395             }
 396
 397             /* Turning on the THRE interrupt on IER can trigger the interrupt
 398              * if LSR.THRE=1, even if it had been masked before by reading IIR.
 399              * This is not in the datasheet, but Windows relies on it.  It is
 400              * unclear if THRE has to be resampled every time THRI becomes
 401              * 1, or only on the rising edge.  Bochs does the latter, and Windows
 402              * always toggles IER to all zeroes and back to all ones, so do the
 403              * same.
 404              *
 405              * If IER.THRI is zero, thr_ipending is not used.  Set it to zero
 406              * so that the thr_ipending subsection is not migrated.
 407              */
 408             if (changed & UART_IER_THRI) {
 409                 if ((s->ier & UART_IER_THRI) && (s->lsr & UART_LSR_THRE)) {
 410                     s->thr_ipending = 1;
 411                 } else {
 412                     s->thr_ipending = 0;
 413                 }
 414             }
 415
 416             if (changed) {
 417                 serial_update_irq(s);
 418             }
 419         }
 420         break;
 421     case 2:
 422         /* Did the enable/disable flag change? If so, make sure FIFOs get flushed */
 423         if ((val ^ s->fcr) & UART_FCR_FE) {
 424             val |= UART_FCR_XFR | UART_FCR_RFR;
 425         }
 426
 427         /* FIFO clear */
 428
 429         if (val & UART_FCR_RFR) {
 430             s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 431             timer_del(s->fifo_timeout_timer);
 432             s->timeout_ipending = 0;
 433             fifo8_reset(&s->recv_fifo);
 434         }
 435
 436         if (val & UART_FCR_XFR) {
 437             s->lsr |= UART_LSR_THRE;
 438             s->thr_ipending = 1;
 439             fifo8_reset(&s->xmit_fifo);
 440         }
 441
 442         serial_write_fcr(s, val & 0xC9);
 443         serial_update_irq(s);
 444         break;
 445     case 3:
 446         {
 447             int break_enable;
 448             s->lcr = val;
 449             serial_update_parameters(s);
 450             break_enable = (val >> 6) & 1;
 451             if (break_enable != s->last_break_enable) {
 452                 s->last_break_enable = break_enable;
 453                 qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
 454                                   &break_enable);
 455             }
 456         }
 457         break;
 458     case 4:
 459         {
 460             int old_mcr = s->mcr;
 461             s->mcr = val & 0x1f;
 462             if (val & UART_MCR_LOOP)
 463                 break;
 464
 465             if (s->poll_msl >= 0 && old_mcr != s->mcr) {
 466                 serial_update_tiocm(s);
 467                 /* Update the modem status after a one-character-send wait-time, since there may be a response
 468                    from the device/computer at the other end of the serial line */
 469                 timer_mod(s->modem_status_poll, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time);
 470             }
 471         }
 472         break;
 473     case 5:
 474         break;
 475     case 6:
 476         break;
 477     case 7:
 478         s->scr = val;
 479         break;
 480     }
 481 }
 482
 483 static uint64_t serial_ioport_read(void *opaque, hwaddr addr, unsigned size)
 484 {
 485     SerialState *s = opaque;
 486     uint32_t ret;
 487
 488     addr &= 7;
 489     switch(addr) {
 490     default:
 491     case 0:
 492         if (s->lcr & UART_LCR_DLAB) {
 493             ret = s->divider & 0xff;
 494         } else {
 495             if(s->fcr & UART_FCR_FE) {
 496                 ret = fifo8_is_empty(&s->recv_fifo) ?
 497                             0 : fifo8_pop(&s->recv_fifo);
 498                 if (s->recv_fifo.num == 0) {
 499                     s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 500                 } else {
 501                     timer_mod(s->fifo_timeout_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time * 4);
 502                 }
 503                 s->timeout_ipending = 0;
 504             } else {
 505                 ret = s->rbr;
 506                 s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 507             }
 508             serial_update_irq(s);
 509             if (!(s->mcr & UART_MCR_LOOP)) {
 510                 /* in loopback mode, don't receive any data */
 511                 qemu_chr_fe_accept_input(&s->chr);
 512             }
 513         }
 514         break;
 515     case 1:
 516         if (s->lcr & UART_LCR_DLAB) {
 517             ret = (s->divider >> 8) & 0xff;
 518         } else {
 519             ret = s->ier;
 520         }
 521         break;
 522     case 2:
 523         ret = s->iir;
 524         if ((ret & UART_IIR_ID) == UART_IIR_THRI) {
 525             s->thr_ipending = 0;
 526             serial_update_irq(s);
 527         }
 528         break;
 529     case 3:
 530         ret = s->lcr;
 531         break;
 532     case 4:
 533         ret = s->mcr;
 534         break;
 535     case 5:
 536         ret = s->lsr;
 537         /* Clear break and overrun interrupts */
 538         if (s->lsr & (UART_LSR_BI|UART_LSR_OE)) {
 539             s->lsr &= ~(UART_LSR_BI|UART_LSR_OE);
 540             serial_update_irq(s);
 541         }
 542         break;
 543     case 6:
 544         if (s->mcr & UART_MCR_LOOP) {
 545             /* in loopback, the modem output pins are connected to the
 546                inputs */
 547             ret = (s->mcr & 0x0c) << 4;
 548             ret |= (s->mcr & 0x02) << 3;
 549             ret |= (s->mcr & 0x01) << 5;
 550         } else {
 551             if (s->poll_msl >= 0)
 552                 serial_update_msl(s);
 553             ret = s->msr;
 554             /* Clear delta bits & msr int after read, if they were set */
 555             if (s->msr & UART_MSR_ANY_DELTA) {
 556                 s->msr &= 0xF0;
 557                 serial_update_irq(s);
 558             }
 559         }
 560         break;
 561     case 7:
 562         ret = s->scr;
 563         break;
 564     }
 565     trace_serial_ioport_read(addr, ret);
 566     return ret;
 567 }
 568
 569 static int serial_can_receive(SerialState *s)
 570 {
 571     if(s->fcr & UART_FCR_FE) {
 572         if (s->recv_fifo.num < UART_FIFO_LENGTH) {
 573             /*
 574              * Advertise (fifo.itl - fifo.count) bytes when count < ITL, and 1
 575              * if above. If UART_FIFO_LENGTH - fifo.count is advertised the
 576              * effect will be to almost always fill the fifo completely before
 577              * the guest has a chance to respond, effectively overriding the ITL
 578              * that the guest has set.
 579              */
 580             return (s->recv_fifo.num <= s->recv_fifo_itl) ?
 581                         s->recv_fifo_itl - s->recv_fifo.num : 1;
 582         } else {
 583             return 0;
 584         }
 585     } else {
 586         return !(s->lsr & UART_LSR_DR);
 587     }
 588 }
 589
 590 static void serial_receive_break(SerialState *s)
 591 {
 592     s->rbr = 0;
 593     /* When the LSR_DR is set a null byte is pushed into the fifo */
 594     recv_fifo_put(s, '\0');
 595     s->lsr |= UART_LSR_BI | UART_LSR_DR;
 596     serial_update_irq(s);
 597 }
 598
 599 /* There's data in recv_fifo and s->rbr has not been read for 4 char transmit times */
 600 static void fifo_timeout_int (void *opaque) {
 601     SerialState *s = opaque;
 602     if (s->recv_fifo.num) {
 603         s->timeout_ipending = 1;
 604         serial_update_irq(s);
 605     }
 606 }
 607
 608 static int serial_can_receive1(void *opaque)
 609 {
 610     SerialState *s = opaque;
 611     return serial_can_receive(s);
 612 }
 613
 614 static void serial_receive1(void *opaque, const uint8_t *buf, int size)
 615 {
 616     SerialState *s = opaque;
 617
 618     if (s->wakeup) {
 619         qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
 620     }
 621     if(s->fcr & UART_FCR_FE) {
 622         int i;
 623         for (i = 0; i < size; i++) {
 624             recv_fifo_put(s, buf[i]);
 625         }
 626         s->lsr |= UART_LSR_DR;
 627         /* call the timeout receive callback in 4 char transmit time */
 628         timer_mod(s->fifo_timeout_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->char_transmit_time * 4);
 629     } else {
 630         if (s->lsr & UART_LSR_DR)
 631             s->lsr |= UART_LSR_OE;
 632         s->rbr = buf[0];
 633         s->lsr |= UART_LSR_DR;
 634     }
 635     serial_update_irq(s);
 636 }
 637
 638 static void serial_event(void *opaque, QEMUChrEvent event)
 639 {
 640     SerialState *s = opaque;
 641     DPRINTF("event %x\n", event);
 642     if (event == CHR_EVENT_BREAK)
 643         serial_receive_break(s);
 644 }
 645
 646 static int serial_pre_save(void *opaque)
 647 {
 648     SerialState *s = opaque;
 649     s->fcr_vmstate = s->fcr;
 650
 651     return 0;
 652 }
 653
 654 static int serial_pre_load(void *opaque)
 655 {
 656     SerialState *s = opaque;
 657     s->thr_ipending = -1;
 658     s->poll_msl = -1;
 659     return 0;
 660 }
 661
 662 static int serial_post_load(void *opaque, int version_id)
 663 {
 664     SerialState *s = opaque;
 665
 666     if (version_id < 3) {
 667         s->fcr_vmstate = 0;
 668     }
 669     if (s->thr_ipending == -1) {
 670         s->thr_ipending = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
 671     }
 672
 673     if (s->tsr_retry > 0) {
 674         /* tsr_retry > 0 implies LSR.TEMT = 0 (transmitter not empty).  */
 675         if (s->lsr & UART_LSR_TEMT) {
 676             error_report("inconsistent state in serial device "
 677                          "(tsr empty, tsr_retry=%d", s->tsr_retry);
 678             return -1;
 679         }
 680
 681         if (s->tsr_retry > MAX_XMIT_RETRY) {
 682             s->tsr_retry = MAX_XMIT_RETRY;
 683         }
 684
 685         assert(s->watch_tag == 0);
 686         s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
 687                                              serial_watch_cb, s);
 688     } else {
 689         /* tsr_retry == 0 implies LSR.TEMT = 1 (transmitter empty).  */
 690         if (!(s->lsr & UART_LSR_TEMT)) {
 691             error_report("inconsistent state in serial device "
 692                          "(tsr not empty, tsr_retry=0");
 693             return -1;
 694         }
 695     }
 696
 697     s->last_break_enable = (s->lcr >> 6) & 1;
 698     /* Initialize fcr via setter to perform essential side-effects */
 699     serial_write_fcr(s, s->fcr_vmstate);
 700     serial_update_parameters(s);
 701     return 0;
 702 }
 703
 704 static bool serial_thr_ipending_needed(void *opaque)
 705 {
 706     SerialState *s = opaque;
 707
 708     if (s->ier & UART_IER_THRI) {
 709         bool expected_value = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
 710         return s->thr_ipending != expected_value;
 711     } else {
 712         /* LSR.THRE will be sampled again when the interrupt is
 713          * enabled.  thr_ipending is not used in this case, do
 714          * not migrate it.
 715          */
 716         return false;
 717     }
 718 }
 719
 720 static const VMStateDescription vmstate_serial_thr_ipending = {
 721     .name = "serial/thr_ipending",
 722     .version_id = 1,
 723     .minimum_version_id = 1,
 724     .needed = serial_thr_ipending_needed,
 725     .fields = (VMStateField[]) {
 726         VMSTATE_INT32(thr_ipending, SerialState),
 727         VMSTATE_END_OF_LIST()
 728     }
 729 };
 730
 731 static bool serial_tsr_needed(void *opaque)
 732 {
 733     SerialState *s = (SerialState *)opaque;
 734     return s->tsr_retry != 0;
 735 }
 736
 737 static const VMStateDescription vmstate_serial_tsr = {
 738     .name = "serial/tsr",
 739     .version_id = 1,
 740     .minimum_version_id = 1,
 741     .needed = serial_tsr_needed,
 742     .fields = (VMStateField[]) {
 743         VMSTATE_UINT32(tsr_retry, SerialState),
 744         VMSTATE_UINT8(thr, SerialState),
 745         VMSTATE_UINT8(tsr, SerialState),
 746         VMSTATE_END_OF_LIST()
 747     }
 748 };
 749
 750 static bool serial_recv_fifo_needed(void *opaque)
 751 {
 752     SerialState *s = (SerialState *)opaque;
 753     return !fifo8_is_empty(&s->recv_fifo);
 754
 755 }
 756
 757 static const VMStateDescription vmstate_serial_recv_fifo = {
 758     .name = "serial/recv_fifo",
 759     .version_id = 1,
 760     .minimum_version_id = 1,
 761     .needed = serial_recv_fifo_needed,
 762     .fields = (VMStateField[]) {
 763         VMSTATE_STRUCT(recv_fifo, SerialState, 1, vmstate_fifo8, Fifo8),
 764         VMSTATE_END_OF_LIST()
 765     }
 766 };
 767
 768 static bool serial_xmit_fifo_needed(void *opaque)
 769 {
 770     SerialState *s = (SerialState *)opaque;
 771     return !fifo8_is_empty(&s->xmit_fifo);
 772 }
 773
 774 static const VMStateDescription vmstate_serial_xmit_fifo = {
 775     .name = "serial/xmit_fifo",
 776     .version_id = 1,
 777     .minimum_version_id = 1,
 778     .needed = serial_xmit_fifo_needed,
 779     .fields = (VMStateField[]) {
 780         VMSTATE_STRUCT(xmit_fifo, SerialState, 1, vmstate_fifo8, Fifo8),
 781         VMSTATE_END_OF_LIST()
 782     }
 783 };
 784
 785 static bool serial_fifo_timeout_timer_needed(void *opaque)
 786 {
 787     SerialState *s = (SerialState *)opaque;
 788     return timer_pending(s->fifo_timeout_timer);
 789 }
 790
 791 static const VMStateDescription vmstate_serial_fifo_timeout_timer = {
 792     .name = "serial/fifo_timeout_timer",
 793     .version_id = 1,
 794     .minimum_version_id = 1,
 795     .needed = serial_fifo_timeout_timer_needed,
 796     .fields = (VMStateField[]) {
 797         VMSTATE_TIMER_PTR(fifo_timeout_timer, SerialState),
 798         VMSTATE_END_OF_LIST()
 799     }
 800 };
 801
 802 static bool serial_timeout_ipending_needed(void *opaque)
 803 {
 804     SerialState *s = (SerialState *)opaque;
 805     return s->timeout_ipending != 0;
 806 }
 807
 808 static const VMStateDescription vmstate_serial_timeout_ipending = {
 809     .name = "serial/timeout_ipending",
 810     .version_id = 1,
 811     .minimum_version_id = 1,
 812     .needed = serial_timeout_ipending_needed,
 813     .fields = (VMStateField[]) {
 814         VMSTATE_INT32(timeout_ipending, SerialState),
 815         VMSTATE_END_OF_LIST()
 816     }
 817 };
 818
 819 static bool serial_poll_needed(void *opaque)
 820 {
 821     SerialState *s = (SerialState *)opaque;
 822     return s->poll_msl >= 0;
 823 }
 824
 825 static const VMStateDescription vmstate_serial_poll = {
 826     .name = "serial/poll",
 827     .version_id = 1,
 828     .needed = serial_poll_needed,
 829     .minimum_version_id = 1,
 830     .fields = (VMStateField[]) {
 831         VMSTATE_INT32(poll_msl, SerialState),
 832         VMSTATE_TIMER_PTR(modem_status_poll, SerialState),
 833         VMSTATE_END_OF_LIST()
 834     }
 835 };
 836
 837 const VMStateDescription vmstate_serial = {
 838     .name = "serial",
 839     .version_id = 3,
 840     .minimum_version_id = 2,
 841     .pre_save = serial_pre_save,
 842     .pre_load = serial_pre_load,
 843     .post_load = serial_post_load,
 844     .fields = (VMStateField[]) {
 845         VMSTATE_UINT16_V(divider, SerialState, 2),
 846         VMSTATE_UINT8(rbr, SerialState),
 847         VMSTATE_UINT8(ier, SerialState),
 848         VMSTATE_UINT8(iir, SerialState),
 849         VMSTATE_UINT8(lcr, SerialState),
 850         VMSTATE_UINT8(mcr, SerialState),
 851         VMSTATE_UINT8(lsr, SerialState),
 852         VMSTATE_UINT8(msr, SerialState),
 853         VMSTATE_UINT8(scr, SerialState),
 854         VMSTATE_UINT8_V(fcr_vmstate, SerialState, 3),
 855         VMSTATE_END_OF_LIST()
 856     },
 857     .subsections = (const VMStateDescription*[]) {
 858         &vmstate_serial_thr_ipending,
 859         &vmstate_serial_tsr,
 860         &vmstate_serial_recv_fifo,
 861         &vmstate_serial_xmit_fifo,
 862         &vmstate_serial_fifo_timeout_timer,
 863         &vmstate_serial_timeout_ipending,
 864         &vmstate_serial_poll,
 865         NULL
 866     }
 867 };
 868
 869 static void serial_reset(void *opaque)
 870 {
 871     SerialState *s = opaque;
 872
 873     if (s->watch_tag > 0) {
 874         g_source_remove(s->watch_tag);
 875         s->watch_tag = 0;
 876     }
 877
 878     s->rbr = 0;
 879     s->ier = 0;
 880     s->iir = UART_IIR_NO_INT;
 881     s->lcr = 0;
 882     s->lsr = UART_LSR_TEMT | UART_LSR_THRE;
 883     s->msr = UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS;
 884     /* Default to 9600 baud, 1 start bit, 8 data bits, 1 stop bit, no parity. */
 885     s->divider = 0x0C;
 886     s->mcr = UART_MCR_OUT2;
 887     s->scr = 0;
 888     s->tsr_retry = 0;
 889     s->char_transmit_time = (NANOSECONDS_PER_SECOND / 9600) * 10;
 890     s->poll_msl = 0;
 891
 892     s->timeout_ipending = 0;
 893     timer_del(s->fifo_timeout_timer);
 894     timer_del(s->modem_status_poll);
 895
 896     fifo8_reset(&s->recv_fifo);
 897     fifo8_reset(&s->xmit_fifo);
 898
 899     s->last_xmit_ts = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 900
 901     s->thr_ipending = 0;
 902     s->last_break_enable = 0;
 903     qemu_irq_lower(s->irq);
 904
 905     serial_update_msl(s);
 906     s->msr &= ~UART_MSR_ANY_DELTA;
 907 }
 908
 909 static int serial_be_change(void *opaque)
 910 {
 911     SerialState *s = opaque;
 912
 913     qemu_chr_fe_set_handlers(&s->chr, serial_can_receive1, serial_receive1,
 914                              serial_event, serial_be_change, s, NULL, true);
 915
 916     serial_update_parameters(s);
 917
 918     qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
 919                       &s->last_break_enable);
 920
 921     s->poll_msl = (s->ier & UART_IER_MSI) ? 1 : 0;
 922     serial_update_msl(s);
 923
 924     if (s->poll_msl >= 0 && !(s->mcr & UART_MCR_LOOP)) {
 925         serial_update_tiocm(s);
 926     }
 927
 928     if (s->watch_tag > 0) {
 929         g_source_remove(s->watch_tag);
 930         s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
 931                                              serial_watch_cb, s);
 932     }
 933
 934     return 0;
 935 }
 936
 937 static void serial_realize(DeviceState *dev, Error **errp)
 938 {
 939     SerialState *s = SERIAL(dev);
 940
 941     s->modem_status_poll = timer_new_ns(QEMU_CLOCK_VIRTUAL, (QEMUTimerCB *) serial_update_msl, s);
 942
 943     s->fifo_timeout_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, (QEMUTimerCB *) fifo_timeout_int, s);
 944     qemu_register_reset(serial_reset, s);
 945
 946     qemu_chr_fe_set_handlers(&s->chr, serial_can_receive1, serial_receive1,
 947                              serial_event, serial_be_change, s, NULL, true);
 948     fifo8_create(&s->recv_fifo, UART_FIFO_LENGTH);
 949     fifo8_create(&s->xmit_fifo, UART_FIFO_LENGTH);
 950     serial_reset(s);
 951 }
 952
 953 static void serial_unrealize(DeviceState *dev, Error **errp)
 954 {
 955     SerialState *s = SERIAL(dev);
 956
 957     qemu_chr_fe_deinit(&s->chr, false);
 958
 959     timer_del(s->modem_status_poll);
 960     timer_free(s->modem_status_poll);
 961
 962     timer_del(s->fifo_timeout_timer);
 963     timer_free(s->fifo_timeout_timer);
 964
 965     fifo8_destroy(&s->recv_fifo);
 966     fifo8_destroy(&s->xmit_fifo);
 967
 968     qemu_unregister_reset(serial_reset, s);
 969 }
 970
 971 /* Change the main reference oscillator frequency. */
 972 void serial_set_frequency(SerialState *s, uint32_t frequency)
 973 {
 974     s->baudbase = frequency;
 975     serial_update_parameters(s);
 976 }
 977
 978 const MemoryRegionOps serial_io_ops = {
 979     .read = serial_ioport_read,
 980     .write = serial_ioport_write,
 981     .impl = {
 982         .min_access_size = 1,
 983         .max_access_size = 1,
 984     },
 985     .endianness = DEVICE_LITTLE_ENDIAN,
 986 };
 987
 988 static void serial_io_realize(DeviceState *dev, Error **errp)
 989 {
 990     SerialIO *sio = SERIAL_IO(dev);
 991     SerialState *s = &sio->serial;
 992     Error *local_err = NULL;
 993
 994     object_property_set_bool(OBJECT(s), true, "realized", &local_err);
 995     if (local_err) {
 996         error_propagate(errp, local_err);
 997         return;
 998     }
 999
1000     memory_region_init_io(&s->io, NULL, &serial_io_ops, s, "serial", 8);
1001     sysbus_init_mmio(SYS_BUS_DEVICE(sio), &s->io);
1002     sysbus_init_irq(SYS_BUS_DEVICE(sio), &s->irq);
1003 }
1004
1005 static void serial_io_class_init(ObjectClass *klass, void* data)
1006 {
1007     DeviceClass *dc = DEVICE_CLASS(klass);
1008
1009     dc->realize = serial_io_realize;
1010     /* No dc->vmsd: class has no migratable state */
1011 }
1012
1013 static void serial_io_instance_init(Object *o)
1014 {
1015     SerialIO *sio = SERIAL_IO(o);
1016
1017     object_initialize_child(o, "serial", &sio->serial, sizeof(sio->serial),
1018                             TYPE_SERIAL, &error_abort, NULL);
1019
1020     qdev_alias_all_properties(DEVICE(&sio->serial), o);
1021 }
1022
1023
1024 static const TypeInfo serial_io_info = {
1025     .name = TYPE_SERIAL_IO,
1026     .parent = TYPE_SYS_BUS_DEVICE,
1027     .instance_size = sizeof(SerialIO),
1028     .instance_init = serial_io_instance_init,
1029     .class_init = serial_io_class_init,
1030 };
1031
1032 static Property serial_properties[] = {
1033     DEFINE_PROP_CHR("chardev", SerialState, chr),
1034     DEFINE_PROP_UINT32("baudbase", SerialState, baudbase, 115200),
1035     DEFINE_PROP_END_OF_LIST(),
1036 };
1037
1038 static void serial_class_init(ObjectClass *klass, void* data)
1039 {
1040     DeviceClass *dc = DEVICE_CLASS(klass);
1041
1042     /* internal device for serialio/serialmm, not user-creatable */
1043     dc->user_creatable = false;
1044     dc->realize = serial_realize;
1045     dc->unrealize = serial_unrealize;
1046     dc->vmsd = &vmstate_serial;
1047     device_class_set_props(dc, serial_properties);
1048 }
1049
1050 static const TypeInfo serial_info = {
1051     .name = TYPE_SERIAL,
1052     .parent = TYPE_DEVICE,
1053     .instance_size = sizeof(SerialState),
1054     .class_init = serial_class_init,
1055 };
1056
1057 /* Memory mapped interface */
1058 static uint64_t serial_mm_read(void *opaque, hwaddr addr,
1059                                unsigned size)
1060 {
1061     SerialMM *s = SERIAL_MM(opaque);
1062     return serial_ioport_read(&s->serial, addr >> s->regshift, 1);
1063 }
1064
1065 static void serial_mm_write(void *opaque, hwaddr addr,
1066                             uint64_t value, unsigned size)
1067 {
1068     SerialMM *s = SERIAL_MM(opaque);
1069     value &= 255;
1070     serial_ioport_write(&s->serial, addr >> s->regshift, value, 1);
1071 }
1072
1073 static const MemoryRegionOps serial_mm_ops[3] = {
1074     [DEVICE_NATIVE_ENDIAN] = {
1075         .read = serial_mm_read,
1076         .write = serial_mm_write,
1077         .endianness = DEVICE_NATIVE_ENDIAN,
1078         .valid.max_access_size = 8,
1079         .impl.max_access_size = 8,
1080     },
1081     [DEVICE_LITTLE_ENDIAN] = {
1082         .read = serial_mm_read,
1083         .write = serial_mm_write,
1084         .endianness = DEVICE_LITTLE_ENDIAN,
1085         .valid.max_access_size = 8,
1086         .impl.max_access_size = 8,
1087     },
1088     [DEVICE_BIG_ENDIAN] = {
1089         .read = serial_mm_read,
1090         .write = serial_mm_write,
1091         .endianness = DEVICE_BIG_ENDIAN,
1092         .valid.max_access_size = 8,
1093         .impl.max_access_size = 8,
1094     },
1095 };
1096
1097 static void serial_mm_realize(DeviceState *dev, Error **errp)
1098 {
1099     SerialMM *smm = SERIAL_MM(dev);
1100     SerialState *s = &smm->serial;
1101     Error *local_err = NULL;
1102
1103     object_property_set_bool(OBJECT(s), true, "realized", &local_err);
1104     if (local_err) {
1105         error_propagate(errp, local_err);
1106         return;
1107     }
1108
1109     memory_region_init_io(&s->io, NULL, &serial_mm_ops[smm->endianness], smm,
1110                           "serial", 8 << smm->regshift);
1111     sysbus_init_mmio(SYS_BUS_DEVICE(smm), &s->io);
1112     sysbus_init_irq(SYS_BUS_DEVICE(smm), &smm->serial.irq);
1113 }
1114
1115 SerialMM *serial_mm_init(MemoryRegion *address_space,
1116                          hwaddr base, int regshift,
1117                          qemu_irq irq, int baudbase,
1118                          Chardev *chr, enum device_endian end)
1119 {
1120     SerialMM *smm = SERIAL_MM(qdev_create(NULL, TYPE_SERIAL_MM));
1121     MemoryRegion *mr;
1122
1123     qdev_prop_set_uint8(DEVICE(smm), "regshift", regshift);
1124     qdev_prop_set_uint32(DEVICE(smm), "baudbase", baudbase);
1125     qdev_prop_set_chr(DEVICE(smm), "chardev", chr);
1126     qdev_set_legacy_instance_id(DEVICE(smm), base, 2);
1127     qdev_prop_set_uint8(DEVICE(smm), "endianness", end);
1128     qdev_init_nofail(DEVICE(smm));
1129
1130     sysbus_connect_irq(SYS_BUS_DEVICE(smm), 0, irq);
1131     mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(smm), 0);
1132     memory_region_add_subregion(address_space, base, mr);
1133
1134     return smm;
1135 }
1136
1137 static void serial_mm_instance_init(Object *o)
1138 {
1139     SerialMM *smm = SERIAL_MM(o);
1140
1141     object_initialize_child(o, "serial", &smm->serial, sizeof(smm->serial),
1142                             TYPE_SERIAL, &error_abort, NULL);
1143
1144     qdev_alias_all_properties(DEVICE(&smm->serial), o);
1145 }
1146
1147 static Property serial_mm_properties[] = {
1148     /*
1149      * Set the spacing between adjacent memory-mapped UART registers.
1150      * Each register will be at (1 << regshift) bytes after the
1151      * previous one.
1152      */
1153     DEFINE_PROP_UINT8("regshift", SerialMM, regshift, 0),
1154     DEFINE_PROP_UINT8("endianness", SerialMM, endianness, DEVICE_NATIVE_ENDIAN),
1155     DEFINE_PROP_END_OF_LIST(),
1156 };
1157
1158 static void serial_mm_class_init(ObjectClass *oc, void *data)
1159 {
1160     DeviceClass *dc = DEVICE_CLASS(oc);
1161
1162     device_class_set_props(dc, serial_mm_properties);
1163     dc->realize = serial_mm_realize;
1164 }
1165
1166 static const TypeInfo serial_mm_info = {
1167     .name = TYPE_SERIAL_MM,
1168     .parent = TYPE_SYS_BUS_DEVICE,
1169     .class_init = serial_mm_class_init,
1170     .instance_init = serial_mm_instance_init,
1171     .instance_size = sizeof(SerialMM),
1172     .class_init = serial_mm_class_init,
1173 };
1174
1175 static void serial_register_types(void)
1176 {
1177     type_register_static(&serial_info);
1178     type_register_static(&serial_io_info);
1179     type_register_static(&serial_mm_info);
1180 }
1181
1182 type_init(serial_register_types)