hw/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 #include "hw.h"
  26 #include "qemu-char.h"
  27 #include "isa.h"
  28 #include "pc.h"
  29 #include "qemu-timer.h"
  30
  31 //#define DEBUG_SERIAL
  32
  33 #define UART_LCR_DLAB   0x80    /* Divisor latch access bit */
  34
  35 #define UART_IER_MSI    0x08    /* Enable Modem status interrupt */
  36 #define UART_IER_RLSI   0x04    /* Enable receiver line status interrupt */
  37 #define UART_IER_THRI   0x02    /* Enable Transmitter holding register int. */
  38 #define UART_IER_RDI    0x01    /* Enable receiver data interrupt */
  39
  40 #define UART_IIR_NO_INT 0x01    /* No interrupts pending */
  41 #define UART_IIR_ID     0x06    /* Mask for the interrupt ID */
  42
  43 #define UART_IIR_MSI    0x00    /* Modem status interrupt */
  44 #define UART_IIR_THRI   0x02    /* Transmitter holding register empty */
  45 #define UART_IIR_RDI    0x04    /* Receiver data interrupt */
  46 #define UART_IIR_RLSI   0x06    /* Receiver line status interrupt */
  47 #define UART_IIR_CTI    0x0C    /* Character Timeout Indication */
  48
  49 #define UART_IIR_FENF   0x80    /* Fifo enabled, but not functionning */
  50 #define UART_IIR_FE     0xC0    /* Fifo enabled */
  51
  52 /*
  53  * These are the definitions for the Modem Control Register
  54  */
  55 #define UART_MCR_LOOP   0x10    /* Enable loopback test mode */
  56 #define UART_MCR_OUT2   0x08    /* Out2 complement */
  57 #define UART_MCR_OUT1   0x04    /* Out1 complement */
  58 #define UART_MCR_RTS    0x02    /* RTS complement */
  59 #define UART_MCR_DTR    0x01    /* DTR complement */
  60
  61 /*
  62  * These are the definitions for the Modem Status Register
  63  */
  64 #define UART_MSR_DCD    0x80    /* Data Carrier Detect */
  65 #define UART_MSR_RI     0x40    /* Ring Indicator */
  66 #define UART_MSR_DSR    0x20    /* Data Set Ready */
  67 #define UART_MSR_CTS    0x10    /* Clear to Send */
  68 #define UART_MSR_DDCD   0x08    /* Delta DCD */
  69 #define UART_MSR_TERI   0x04    /* Trailing edge ring indicator */
  70 #define UART_MSR_DDSR   0x02    /* Delta DSR */
  71 #define UART_MSR_DCTS   0x01    /* Delta CTS */
  72 #define UART_MSR_ANY_DELTA 0x0F /* Any of the delta bits! */
  73
  74 #define UART_LSR_TEMT   0x40    /* Transmitter empty */
  75 #define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
  76 #define UART_LSR_BI     0x10    /* Break interrupt indicator */
  77 #define UART_LSR_FE     0x08    /* Frame error indicator */
  78 #define UART_LSR_PE     0x04    /* Parity error indicator */
  79 #define UART_LSR_OE     0x02    /* Overrun error indicator */
  80 #define UART_LSR_DR     0x01    /* Receiver data ready */
  81 #define UART_LSR_INT_ANY 0x1E   /* Any of the lsr-interrupt-triggering status bits */
  82
  83 /* Interrupt trigger levels. The byte-counts are for 16550A - in newer UARTs the byte-count for each ITL is higher. */
  84
  85 #define UART_FCR_ITL_1      0x00 /* 1 byte ITL */
  86 #define UART_FCR_ITL_2      0x40 /* 4 bytes ITL */
  87 #define UART_FCR_ITL_3      0x80 /* 8 bytes ITL */
  88 #define UART_FCR_ITL_4      0xC0 /* 14 bytes ITL */
  89
  90 #define UART_FCR_DMS        0x08    /* DMA Mode Select */
  91 #define UART_FCR_XFR        0x04    /* XMIT Fifo Reset */
  92 #define UART_FCR_RFR        0x02    /* RCVR Fifo Reset */
  93 #define UART_FCR_FE         0x01    /* FIFO Enable */
  94
  95 #define UART_FIFO_LENGTH    16      /* 16550A Fifo Length */
  96
  97 #define XMIT_FIFO           0
  98 #define RECV_FIFO           1
  99 #define MAX_XMIT_RETRY      4
 100
 101 struct SerialFIFO {
 102     uint8_t data[UART_FIFO_LENGTH];
 103     uint8_t count;
 104     uint8_t itl;                        /* Interrupt Trigger Level */
 105     uint8_t tail;
 106     uint8_t head;
 107 } typedef SerialFIFO;
 108
 109 struct SerialState {
 110     uint16_t divider;
 111     uint8_t rbr; /* receive register */
 112     uint8_t thr; /* transmit holding register */
 113     uint8_t tsr; /* transmit shift register */
 114     uint8_t ier;
 115     uint8_t iir; /* read only */
 116     uint8_t lcr;
 117     uint8_t mcr;
 118     uint8_t lsr; /* read only */
 119     uint8_t msr; /* read only */
 120     uint8_t scr;
 121     uint8_t fcr;
 122     /* NOTE: this hidden state is necessary for tx irq generation as
 123        it can be reset while reading iir */
 124     int thr_ipending;
 125     qemu_irq irq;
 126     CharDriverState *chr;
 127     int last_break_enable;
 128     int it_shift;
 129     int baudbase;
 130     int tsr_retry;
 131
 132     uint64_t last_xmit_ts;              /* Time when the last byte was successfully sent out of the tsr */
 133     SerialFIFO recv_fifo;
 134     SerialFIFO xmit_fifo;
 135
 136     struct QEMUTimer *fifo_timeout_timer;
 137     int timeout_ipending;                   /* timeout interrupt pending state */
 138     struct QEMUTimer *transmit_timer;
 139
 140
 141     uint64_t char_transmit_time;               /* time to transmit a char in ticks*/
 142     int poll_msl;
 143
 144     struct QEMUTimer *modem_status_poll;
 145 };
 146
 147 static void serial_receive1(void *opaque, const uint8_t *buf, int size);
 148
 149 static void fifo_clear(SerialState *s, int fifo)
 150 {
 151     SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
 152     memset(f->data, 0, UART_FIFO_LENGTH);
 153     f->count = 0;
 154     f->head = 0;
 155     f->tail = 0;
 156 }
 157
 158 static int fifo_put(SerialState *s, int fifo, uint8_t chr)
 159 {
 160     SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
 161
 162     f->data[f->head++] = chr;
 163
 164     if (f->head == UART_FIFO_LENGTH)
 165         f->head = 0;
 166     f->count++;
 167
 168     return 1;
 169 }
 170
 171 static uint8_t fifo_get(SerialState *s, int fifo)
 172 {
 173     SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
 174     uint8_t c;
 175
 176     if(f->count == 0)
 177         return 0;
 178
 179     c = f->data[f->tail++];
 180     if (f->tail == UART_FIFO_LENGTH)
 181         f->tail = 0;
 182     f->count--;
 183
 184     return c;
 185 }
 186
 187 static void serial_update_irq(SerialState *s)
 188 {
 189     uint8_t tmp_iir = UART_IIR_NO_INT;
 190
 191     if ((s->ier & UART_IER_RLSI) && (s->lsr & UART_LSR_INT_ANY)) {
 192         tmp_iir = UART_IIR_RLSI;
 193     } else if ((s->ier & UART_IER_RDI) && s->timeout_ipending) {
 194         /* Note that(s->ier & UART_IER_RDI) can mask this interrupt,
 195          * this is not in the specification but is observed on existing
 196          * hardware.  */
 197         tmp_iir = UART_IIR_CTI;
 198     } else if ((s->ier & UART_IER_RDI) && (s->lsr & UART_LSR_DR)) {
 199         if (!(s->fcr & UART_FCR_FE)) {
 200            tmp_iir = UART_IIR_RDI;
 201         } else if (s->recv_fifo.count >= s->recv_fifo.itl) {
 202            tmp_iir = UART_IIR_RDI;
 203         }
 204     } else if ((s->ier & UART_IER_THRI) && s->thr_ipending) {
 205         tmp_iir = UART_IIR_THRI;
 206     } else if ((s->ier & UART_IER_MSI) && (s->msr & UART_MSR_ANY_DELTA)) {
 207         tmp_iir = UART_IIR_MSI;
 208     }
 209
 210     s->iir = tmp_iir | (s->iir & 0xF0);
 211
 212     if (tmp_iir != UART_IIR_NO_INT) {
 213         qemu_irq_raise(s->irq);
 214     } else {
 215         qemu_irq_lower(s->irq);
 216     }
 217 }
 218
 219 static void serial_update_parameters(SerialState *s)
 220 {
 221     int speed, parity, data_bits, stop_bits, frame_size;
 222     QEMUSerialSetParams ssp;
 223
 224     if (s->divider == 0)
 225         return;
 226
 227     frame_size = 1;
 228     if (s->lcr & 0x08) {
 229         if (s->lcr & 0x10)
 230             parity = 'E';
 231         else
 232             parity = 'O';
 233     } else {
 234             parity = 'N';
 235             frame_size = 0;
 236     }
 237     if (s->lcr & 0x04)
 238         stop_bits = 2;
 239     else
 240         stop_bits = 1;
 241
 242     data_bits = (s->lcr & 0x03) + 5;
 243     frame_size += data_bits + stop_bits;
 244     speed = s->baudbase / s->divider;
 245     ssp.speed = speed;
 246     ssp.parity = parity;
 247     ssp.data_bits = data_bits;
 248     ssp.stop_bits = stop_bits;
 249     s->char_transmit_time =  (ticks_per_sec / speed) * frame_size;
 250     qemu_chr_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
 251 #if 0
 252     printf("speed=%d parity=%c data=%d stop=%d\n",
 253            speed, parity, data_bits, stop_bits);
 254 #endif
 255 }
 256
 257 static void serial_update_msl(SerialState *s)
 258 {
 259     uint8_t omsr;
 260     int flags;
 261
 262     qemu_del_timer(s->modem_status_poll);
 263
 264     if (qemu_chr_ioctl(s->chr,CHR_IOCTL_SERIAL_GET_TIOCM, &flags) == -ENOTSUP) {
 265         s->poll_msl = -1;
 266         return;
 267     }
 268
 269     omsr = s->msr;
 270
 271     s->msr = (flags & CHR_TIOCM_CTS) ? s->msr | UART_MSR_CTS : s->msr & ~UART_MSR_CTS;
 272     s->msr = (flags & CHR_TIOCM_DSR) ? s->msr | UART_MSR_DSR : s->msr & ~UART_MSR_DSR;
 273     s->msr = (flags & CHR_TIOCM_CAR) ? s->msr | UART_MSR_DCD : s->msr & ~UART_MSR_DCD;
 274     s->msr = (flags & CHR_TIOCM_RI) ? s->msr | UART_MSR_RI : s->msr & ~UART_MSR_RI;
 275
 276     if (s->msr != omsr) {
 277          /* Set delta bits */
 278          s->msr = s->msr | ((s->msr >> 4) ^ (omsr >> 4));
 279          /* UART_MSR_TERI only if change was from 1 -> 0 */
 280          if ((s->msr & UART_MSR_TERI) && !(omsr & UART_MSR_RI))
 281              s->msr &= ~UART_MSR_TERI;
 282          serial_update_irq(s);
 283     }
 284
 285     /* The real 16550A apparently has a 250ns response latency to line status changes.
 286        We'll be lazy and poll only every 10ms, and only poll it at all if MSI interrupts are turned on */
 287
 288     if (s->poll_msl)
 289         qemu_mod_timer(s->modem_status_poll, qemu_get_clock(vm_clock) + ticks_per_sec / 100);
 290 }
 291
 292 static void serial_xmit(void *opaque)
 293 {
 294     SerialState *s = opaque;
 295     uint64_t new_xmit_ts = qemu_get_clock(vm_clock);
 296
 297     if (s->tsr_retry <= 0) {
 298         if (s->fcr & UART_FCR_FE) {
 299             s->tsr = fifo_get(s,XMIT_FIFO);
 300             if (!s->xmit_fifo.count)
 301                 s->lsr |= UART_LSR_THRE;
 302         } else {
 303             s->tsr = s->thr;
 304             s->lsr |= UART_LSR_THRE;
 305         }
 306     }
 307
 308     if (s->mcr & UART_MCR_LOOP) {
 309         /* in loopback mode, say that we just received a char */
 310         serial_receive1(s, &s->tsr, 1);
 311     } else if (qemu_chr_write(s->chr, &s->tsr, 1) != 1) {
 312         if ((s->tsr_retry > 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
 313             s->tsr_retry++;
 314             qemu_mod_timer(s->transmit_timer,  new_xmit_ts + s->char_transmit_time);
 315             return;
 316         } else if (s->poll_msl < 0) {
 317             /* If we exceed MAX_XMIT_RETRY and the backend is not a real serial port, then
 318             drop any further failed writes instantly, until we get one that goes through.
 319             This is to prevent guests that log to unconnected pipes or pty's from stalling. */
 320             s->tsr_retry = -1;
 321         }
 322     }
 323     else {
 324         s->tsr_retry = 0;
 325     }
 326
 327     s->last_xmit_ts = qemu_get_clock(vm_clock);
 328     if (!(s->lsr & UART_LSR_THRE))
 329         qemu_mod_timer(s->transmit_timer, s->last_xmit_ts + s->char_transmit_time);
 330
 331     if (s->lsr & UART_LSR_THRE) {
 332         s->lsr |= UART_LSR_TEMT;
 333         s->thr_ipending = 1;
 334         serial_update_irq(s);
 335     }
 336 }
 337
 338
 339 static void serial_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 340 {
 341     SerialState *s = opaque;
 342
 343     addr &= 7;
 344 #ifdef DEBUG_SERIAL
 345     printf("serial: write addr=0x%02x val=0x%02x\n", addr, val);
 346 #endif
 347     switch(addr) {
 348     default:
 349     case 0:
 350         if (s->lcr & UART_LCR_DLAB) {
 351             s->divider = (s->divider & 0xff00) | val;
 352             serial_update_parameters(s);
 353         } else {
 354             s->thr = (uint8_t) val;
 355             if(s->fcr & UART_FCR_FE) {
 356                   fifo_put(s, XMIT_FIFO, s->thr);
 357             s->thr_ipending = 0;
 358                   s->lsr &= ~UART_LSR_TEMT;
 359             s->lsr &= ~UART_LSR_THRE;
 360             serial_update_irq(s);
 361             } else {
 362                   s->thr_ipending = 0;
 363                   s->lsr &= ~UART_LSR_THRE;
 364                   serial_update_irq(s);
 365             }
 366             serial_xmit(s);
 367         }
 368         break;
 369     case 1:
 370         if (s->lcr & UART_LCR_DLAB) {
 371             s->divider = (s->divider & 0x00ff) | (val << 8);
 372             serial_update_parameters(s);
 373         } else {
 374             s->ier = val & 0x0f;
 375             /* If the backend device is a real serial port, turn polling of the modem
 376                status lines on physical port on or off depending on UART_IER_MSI state */
 377             if (s->poll_msl >= 0) {
 378                 if (s->ier & UART_IER_MSI) {
 379                      s->poll_msl = 1;
 380                      serial_update_msl(s);
 381                 } else {
 382                      qemu_del_timer(s->modem_status_poll);
 383                      s->poll_msl = 0;
 384                 }
 385             }
 386             if (s->lsr & UART_LSR_THRE) {
 387                 s->thr_ipending = 1;
 388                 serial_update_irq(s);
 389             }
 390         }
 391         break;
 392     case 2:
 393         val = val & 0xFF;
 394
 395         if (s->fcr == val)
 396             break;
 397
 398         /* Did the enable/disable flag change? If so, make sure FIFOs get flushed */
 399         if ((val ^ s->fcr) & UART_FCR_FE)
 400             val |= UART_FCR_XFR | UART_FCR_RFR;
 401
 402         /* FIFO clear */
 403
 404         if (val & UART_FCR_RFR) {
 405             qemu_del_timer(s->fifo_timeout_timer);
 406             s->timeout_ipending=0;
 407             fifo_clear(s,RECV_FIFO);
 408         }
 409
 410         if (val & UART_FCR_XFR) {
 411             fifo_clear(s,XMIT_FIFO);
 412         }
 413
 414         if (val & UART_FCR_FE) {
 415             s->iir |= UART_IIR_FE;
 416             /* Set RECV_FIFO trigger Level */
 417             switch (val & 0xC0) {
 418             case UART_FCR_ITL_1:
 419                 s->recv_fifo.itl = 1;
 420                 break;
 421             case UART_FCR_ITL_2:
 422                 s->recv_fifo.itl = 4;
 423                 break;
 424             case UART_FCR_ITL_3:
 425                 s->recv_fifo.itl = 8;
 426                 break;
 427             case UART_FCR_ITL_4:
 428                 s->recv_fifo.itl = 14;
 429                 break;
 430             }
 431         } else
 432             s->iir &= ~UART_IIR_FE;
 433
 434         /* Set fcr - or at least the bits in it that are supposed to "stick" */
 435         s->fcr = val & 0xC9;
 436         serial_update_irq(s);
 437         break;
 438     case 3:
 439         {
 440             int break_enable;
 441             s->lcr = val;
 442             serial_update_parameters(s);
 443             break_enable = (val >> 6) & 1;
 444             if (break_enable != s->last_break_enable) {
 445                 s->last_break_enable = break_enable;
 446                 qemu_chr_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
 447                                &break_enable);
 448             }
 449         }
 450         break;
 451     case 4:
 452         {
 453             int flags;
 454             int old_mcr = s->mcr;
 455             s->mcr = val & 0x1f;
 456             if (val & UART_MCR_LOOP)
 457                 break;
 458
 459             if (s->poll_msl >= 0 && old_mcr != s->mcr) {
 460
 461                 qemu_chr_ioctl(s->chr,CHR_IOCTL_SERIAL_GET_TIOCM, &flags);
 462
 463                 flags &= ~(CHR_TIOCM_RTS | CHR_TIOCM_DTR);
 464
 465                 if (val & UART_MCR_RTS)
 466                     flags |= CHR_TIOCM_RTS;
 467                 if (val & UART_MCR_DTR)
 468                     flags |= CHR_TIOCM_DTR;
 469
 470                 qemu_chr_ioctl(s->chr,CHR_IOCTL_SERIAL_SET_TIOCM, &flags);
 471                 /* Update the modem status after a one-character-send wait-time, since there may be a response
 472                    from the device/computer at the other end of the serial line */
 473                 qemu_mod_timer(s->modem_status_poll, qemu_get_clock(vm_clock) + s->char_transmit_time);
 474             }
 475         }
 476         break;
 477     case 5:
 478         break;
 479     case 6:
 480         break;
 481     case 7:
 482         s->scr = val;
 483         break;
 484     }
 485 }
 486
 487 static uint32_t serial_ioport_read(void *opaque, uint32_t addr)
 488 {
 489     SerialState *s = opaque;
 490     uint32_t ret;
 491
 492     addr &= 7;
 493     switch(addr) {
 494     default:
 495     case 0:
 496         if (s->lcr & UART_LCR_DLAB) {
 497             ret = s->divider & 0xff;
 498         } else {
 499             if(s->fcr & UART_FCR_FE) {
 500                 ret = fifo_get(s,RECV_FIFO);
 501                 if (s->recv_fifo.count == 0)
 502                     s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 503                 else
 504                     qemu_mod_timer(s->fifo_timeout_timer, qemu_get_clock (vm_clock) + s->char_transmit_time * 4);
 505                 s->timeout_ipending = 0;
 506             } else {
 507                 ret = s->rbr;
 508                 s->lsr &= ~(UART_LSR_DR | UART_LSR_BI);
 509             }
 510             serial_update_irq(s);
 511             if (!(s->mcr & UART_MCR_LOOP)) {
 512                 /* in loopback mode, don't receive any data */
 513                 qemu_chr_accept_input(s->chr);
 514             }
 515         }
 516         break;
 517     case 1:
 518         if (s->lcr & UART_LCR_DLAB) {
 519             ret = (s->divider >> 8) & 0xff;
 520         } else {
 521             ret = s->ier;
 522         }
 523         break;
 524     case 2:
 525         ret = s->iir;
 526             s->thr_ipending = 0;
 527         serial_update_irq(s);
 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 interrupt */
 538         if (s->lsr & UART_LSR_BI) {
 539             s->lsr &= ~UART_LSR_BI;
 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 #ifdef DEBUG_SERIAL
 566     printf("serial: read addr=0x%02x val=0x%02x\n", addr, ret);
 567 #endif
 568     return ret;
 569 }
 570
 571 static int serial_can_receive(SerialState *s)
 572 {
 573     if(s->fcr & UART_FCR_FE) {
 574         if(s->recv_fifo.count < UART_FIFO_LENGTH)
 575         /* Advertise (fifo.itl - fifo.count) bytes when count < ITL, and 1 if above. If UART_FIFO_LENGTH - fifo.count is
 576         advertised the effect will be to almost always fill the fifo completely before the guest has a chance to respond,
 577         effectively overriding the ITL that the guest has set. */
 578              return (s->recv_fifo.count <= s->recv_fifo.itl) ? s->recv_fifo.itl - s->recv_fifo.count : 1;
 579         else
 580              return 0;
 581     } else {
 582     return !(s->lsr & UART_LSR_DR);
 583     }
 584 }
 585
 586 static void serial_receive_break(SerialState *s)
 587 {
 588     s->rbr = 0;
 589     /* When the LSR_DR is set a null byte is pushed into the fifo */
 590     fifo_put(s, RECV_FIFO, '\0');
 591     s->lsr |= UART_LSR_BI | UART_LSR_DR;
 592     serial_update_irq(s);
 593 }
 594
 595 /* There's data in recv_fifo and s->rbr has not been read for 4 char transmit times */
 596 static void fifo_timeout_int (void *opaque) {
 597     SerialState *s = opaque;
 598     if (s->recv_fifo.count) {
 599         s->timeout_ipending = 1;
 600         serial_update_irq(s);
 601     }
 602 }
 603
 604 static int serial_can_receive1(void *opaque)
 605 {
 606     SerialState *s = opaque;
 607     return serial_can_receive(s);
 608 }
 609
 610 static void serial_receive1(void *opaque, const uint8_t *buf, int size)
 611 {
 612     SerialState *s = opaque;
 613     if(s->fcr & UART_FCR_FE) {
 614         int i;
 615         for (i = 0; i < size; i++) {
 616             fifo_put(s, RECV_FIFO, buf[i]);
 617         }
 618         s->lsr |= UART_LSR_DR;
 619         /* call the timeout receive callback in 4 char transmit time */
 620         qemu_mod_timer(s->fifo_timeout_timer, qemu_get_clock (vm_clock) + s->char_transmit_time * 4);
 621     } else {
 622         s->rbr = buf[0];
 623         s->lsr |= UART_LSR_DR;
 624     }
 625     serial_update_irq(s);
 626 }
 627
 628 static void serial_event(void *opaque, int event)
 629 {
 630     SerialState *s = opaque;
 631 #ifdef DEBUG_SERIAL
 632     printf("serial: event %x\n", event);
 633 #endif
 634     if (event == CHR_EVENT_BREAK)
 635         serial_receive_break(s);
 636 }
 637
 638 static void serial_save(QEMUFile *f, void *opaque)
 639 {
 640     SerialState *s = opaque;
 641
 642     qemu_put_be16s(f,&s->divider);
 643     qemu_put_8s(f,&s->rbr);
 644     qemu_put_8s(f,&s->ier);
 645     qemu_put_8s(f,&s->iir);
 646     qemu_put_8s(f,&s->lcr);
 647     qemu_put_8s(f,&s->mcr);
 648     qemu_put_8s(f,&s->lsr);
 649     qemu_put_8s(f,&s->msr);
 650     qemu_put_8s(f,&s->scr);
 651     qemu_put_8s(f,&s->fcr);
 652 }
 653
 654 static int serial_load(QEMUFile *f, void *opaque, int version_id)
 655 {
 656     SerialState *s = opaque;
 657     uint8_t fcr = 0;
 658
 659     if(version_id > 3)
 660         return -EINVAL;
 661
 662     if (version_id >= 2)
 663         qemu_get_be16s(f, &s->divider);
 664     else
 665         s->divider = qemu_get_byte(f);
 666     qemu_get_8s(f,&s->rbr);
 667     qemu_get_8s(f,&s->ier);
 668     qemu_get_8s(f,&s->iir);
 669     qemu_get_8s(f,&s->lcr);
 670     qemu_get_8s(f,&s->mcr);
 671     qemu_get_8s(f,&s->lsr);
 672     qemu_get_8s(f,&s->msr);
 673     qemu_get_8s(f,&s->scr);
 674
 675     if (version_id >= 3)
 676         qemu_get_8s(f,&fcr);
 677
 678     /* Initialize fcr via setter to perform essential side-effects */
 679     serial_ioport_write(s, 0x02, fcr);
 680     return 0;
 681 }
 682
 683 static void serial_reset(void *opaque)
 684 {
 685     SerialState *s = opaque;
 686
 687     s->rbr = 0;
 688     s->ier = 0;
 689     s->iir = UART_IIR_NO_INT;
 690     s->lcr = 0;
 691     s->lsr = UART_LSR_TEMT | UART_LSR_THRE;
 692     s->msr = UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS;
 693     /* Default to 9600 baud, no parity, one stop bit */
 694     s->divider = 0x0C;
 695     s->mcr = UART_MCR_OUT2;
 696     s->scr = 0;
 697     s->tsr_retry = 0;
 698     s->char_transmit_time = (ticks_per_sec / 9600) * 9;
 699     s->poll_msl = 0;
 700
 701     fifo_clear(s,RECV_FIFO);
 702     fifo_clear(s,XMIT_FIFO);
 703
 704     s->last_xmit_ts = qemu_get_clock(vm_clock);
 705
 706     s->thr_ipending = 0;
 707     s->last_break_enable = 0;
 708     qemu_irq_lower(s->irq);
 709 }
 710
 711 static void serial_init_core(SerialState *s, qemu_irq irq, int baudbase,
 712                              CharDriverState *chr)
 713 {
 714     s->irq = irq;
 715     s->baudbase = baudbase;
 716     s->chr = chr ?: qemu_chr_open("null", "null", NULL);
 717
 718     s->modem_status_poll = qemu_new_timer(vm_clock, (QEMUTimerCB *) serial_update_msl, s);
 719
 720     s->fifo_timeout_timer = qemu_new_timer(vm_clock, (QEMUTimerCB *) fifo_timeout_int, s);
 721     s->transmit_timer = qemu_new_timer(vm_clock, (QEMUTimerCB *) serial_xmit, s);
 722
 723     qemu_register_reset(serial_reset, 0, s);
 724     serial_reset(s);
 725
 726     qemu_chr_add_handlers(s->chr, serial_can_receive1, serial_receive1,
 727                           serial_event, s);
 728 }
 729
 730 /* If fd is zero, it means that the serial device uses the console */
 731 SerialState *serial_init(int base, qemu_irq irq, int baudbase,
 732                          CharDriverState *chr)
 733 {
 734     SerialState *s;
 735
 736     s = qemu_mallocz(sizeof(SerialState));
 737
 738     serial_init_core(s, irq, baudbase, chr);
 739
 740     register_savevm("serial", base, 3, serial_save, serial_load, s);
 741
 742     register_ioport_write(base, 8, 1, serial_ioport_write, s);
 743     register_ioport_read(base, 8, 1, serial_ioport_read, s);
 744     return s;
 745 }
 746
 747 /* Memory mapped interface */
 748 uint32_t serial_mm_readb (void *opaque, target_phys_addr_t addr)
 749 {
 750     SerialState *s = opaque;
 751
 752     return serial_ioport_read(s, addr >> s->it_shift) & 0xFF;
 753 }
 754
 755 void serial_mm_writeb (void *opaque,
 756                        target_phys_addr_t addr, uint32_t value)
 757 {
 758     SerialState *s = opaque;
 759
 760     serial_ioport_write(s, addr >> s->it_shift, value & 0xFF);
 761 }
 762
 763 uint32_t serial_mm_readw (void *opaque, target_phys_addr_t addr)
 764 {
 765     SerialState *s = opaque;
 766     uint32_t val;
 767
 768     val = serial_ioport_read(s, addr >> s->it_shift) & 0xFFFF;
 769 #ifdef TARGET_WORDS_BIGENDIAN
 770     val = bswap16(val);
 771 #endif
 772     return val;
 773 }
 774
 775 void serial_mm_writew (void *opaque,
 776                        target_phys_addr_t addr, uint32_t value)
 777 {
 778     SerialState *s = opaque;
 779 #ifdef TARGET_WORDS_BIGENDIAN
 780     value = bswap16(value);
 781 #endif
 782     serial_ioport_write(s, addr >> s->it_shift, value & 0xFFFF);
 783 }
 784
 785 uint32_t serial_mm_readl (void *opaque, target_phys_addr_t addr)
 786 {
 787     SerialState *s = opaque;
 788     uint32_t val;
 789
 790     val = serial_ioport_read(s, addr >> s->it_shift);
 791 #ifdef TARGET_WORDS_BIGENDIAN
 792     val = bswap32(val);
 793 #endif
 794     return val;
 795 }
 796
 797 void serial_mm_writel (void *opaque,
 798                        target_phys_addr_t addr, uint32_t value)
 799 {
 800     SerialState *s = opaque;
 801 #ifdef TARGET_WORDS_BIGENDIAN
 802     value = bswap32(value);
 803 #endif
 804     serial_ioport_write(s, addr >> s->it_shift, value);
 805 }
 806
 807 static CPUReadMemoryFunc *serial_mm_read[] = {
 808     &serial_mm_readb,
 809     &serial_mm_readw,
 810     &serial_mm_readl,
 811 };
 812
 813 static CPUWriteMemoryFunc *serial_mm_write[] = {
 814     &serial_mm_writeb,
 815     &serial_mm_writew,
 816     &serial_mm_writel,
 817 };
 818
 819 SerialState *serial_mm_init (target_phys_addr_t base, int it_shift,
 820                              qemu_irq irq, int baudbase,
 821                              CharDriverState *chr, int ioregister)
 822 {
 823     SerialState *s;
 824     int s_io_memory;
 825
 826     s = qemu_mallocz(sizeof(SerialState));
 827
 828     s->it_shift = it_shift;
 829
 830     serial_init_core(s, irq, baudbase, chr);
 831     register_savevm("serial", base, 3, serial_save, serial_load, s);
 832
 833     if (ioregister) {
 834         s_io_memory = cpu_register_io_memory(serial_mm_read,
 835                                              serial_mm_write, s);
 836         cpu_register_physical_memory(base, 8 << it_shift, s_io_memory);
 837     }
 838     serial_update_msl(s);
 839     return s;
 840 }