hw/net/fsl_etsec/rings.c

   1 /*
   2  * QEMU Freescale eTSEC Emulator
   3  *
   4  * Copyright (c) 2011-2013 AdaCore
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "qemu/osdep.h"
  25 #include "net/checksum.h"
  26 #include "qemu/log.h"
  27 #include "etsec.h"
  28 #include "registers.h"
  29
  30 /* #define ETSEC_RING_DEBUG */
  31 /* #define HEX_DUMP */
  32 /* #define DEBUG_BD */
  33
  34 #ifdef ETSEC_RING_DEBUG
  35 static const int debug_etsec = 1;
  36 #else
  37 static const int debug_etsec;
  38 #endif
  39
  40 #define RING_DEBUG(fmt, ...) do {              \
  41  if (debug_etsec) {                            \
  42         qemu_log(fmt , ## __VA_ARGS__);        \
  43     }                                          \
  44     } while (0)
  45
  46 #ifdef DEBUG_BD
  47
  48 static void print_tx_bd_flags(uint16_t flags)
  49 {
  50     qemu_log("      Ready: %d\n", !!(flags & BD_TX_READY));
  51     qemu_log("      PAD/CRC: %d\n", !!(flags & BD_TX_PADCRC));
  52     qemu_log("      Wrap: %d\n", !!(flags & BD_WRAP));
  53     qemu_log("      Interrupt: %d\n", !!(flags & BD_INTERRUPT));
  54     qemu_log("      Last in frame: %d\n", !!(flags & BD_LAST));
  55     qemu_log("      Tx CRC: %d\n", !!(flags & BD_TX_TC));
  56     qemu_log("      User-defined preamble / defer: %d\n",
  57            !!(flags & BD_TX_PREDEF));
  58     qemu_log("      Huge frame enable / Late collision: %d\n",
  59            !!(flags & BD_TX_HFELC));
  60     qemu_log("      Control frame / Retransmission Limit: %d\n",
  61            !!(flags & BD_TX_CFRL));
  62     qemu_log("      Retry count: %d\n",
  63            (flags >> BD_TX_RC_OFFSET) & BD_TX_RC_MASK);
  64     qemu_log("      Underrun / TCP/IP off-load enable: %d\n",
  65            !!(flags & BD_TX_TOEUN));
  66     qemu_log("      Truncation: %d\n", !!(flags & BD_TX_TR));
  67 }
  68
  69 static void print_rx_bd_flags(uint16_t flags)
  70 {
  71     qemu_log("      Empty: %d\n", !!(flags & BD_RX_EMPTY));
  72     qemu_log("      Receive software ownership: %d\n", !!(flags & BD_RX_RO1));
  73     qemu_log("      Wrap: %d\n", !!(flags & BD_WRAP));
  74     qemu_log("      Interrupt: %d\n", !!(flags & BD_INTERRUPT));
  75     qemu_log("      Last in frame: %d\n", !!(flags & BD_LAST));
  76     qemu_log("      First in frame: %d\n", !!(flags & BD_RX_FIRST));
  77     qemu_log("      Miss: %d\n", !!(flags & BD_RX_MISS));
  78     qemu_log("      Broadcast: %d\n", !!(flags & BD_RX_BROADCAST));
  79     qemu_log("      Multicast: %d\n", !!(flags & BD_RX_MULTICAST));
  80     qemu_log("      Rx frame length violation: %d\n", !!(flags & BD_RX_LG));
  81     qemu_log("      Rx non-octet aligned frame: %d\n", !!(flags & BD_RX_NO));
  82     qemu_log("      Short frame: %d\n", !!(flags & BD_RX_SH));
  83     qemu_log("      Rx CRC Error: %d\n", !!(flags & BD_RX_CR));
  84     qemu_log("      Overrun: %d\n", !!(flags & BD_RX_OV));
  85     qemu_log("      Truncation: %d\n", !!(flags & BD_RX_TR));
  86 }
  87
  88
  89 static void print_bd(eTSEC_rxtx_bd bd, int mode, uint32_t index)
  90 {
  91     qemu_log("eTSEC %s Data Buffer Descriptor (%u)\n",
  92            mode == eTSEC_TRANSMIT ? "Transmit" : "Receive",
  93            index);
  94     qemu_log("   Flags   : 0x%04x\n", bd.flags);
  95     if (mode == eTSEC_TRANSMIT) {
  96         print_tx_bd_flags(bd.flags);
  97     } else {
  98         print_rx_bd_flags(bd.flags);
  99     }
 100     qemu_log("   Length  : 0x%04x\n", bd.length);
 101     qemu_log("   Pointer : 0x%08x\n", bd.bufptr);
 102 }
 103
 104 #endif  /* DEBUG_BD */
 105
 106 static void read_buffer_descriptor(eTSEC         *etsec,
 107                                    hwaddr         addr,
 108                                    eTSEC_rxtx_bd *bd)
 109 {
 110     assert(bd != NULL);
 111
 112     RING_DEBUG("READ Buffer Descriptor @ 0x" HWADDR_FMT_plx"\n", addr);
 113     cpu_physical_memory_read(addr,
 114                              bd,
 115                              sizeof(eTSEC_rxtx_bd));
 116
 117     if (etsec->regs[DMACTRL].value & DMACTRL_LE) {
 118         bd->flags  = lduw_le_p(&bd->flags);
 119         bd->length = lduw_le_p(&bd->length);
 120         bd->bufptr = ldl_le_p(&bd->bufptr);
 121     } else {
 122         bd->flags  = lduw_be_p(&bd->flags);
 123         bd->length = lduw_be_p(&bd->length);
 124         bd->bufptr = ldl_be_p(&bd->bufptr);
 125     }
 126 }
 127
 128 static void write_buffer_descriptor(eTSEC         *etsec,
 129                                     hwaddr         addr,
 130                                     eTSEC_rxtx_bd *bd)
 131 {
 132     assert(bd != NULL);
 133
 134     if (etsec->regs[DMACTRL].value & DMACTRL_LE) {
 135         stw_le_p(&bd->flags, bd->flags);
 136         stw_le_p(&bd->length, bd->length);
 137         stl_le_p(&bd->bufptr, bd->bufptr);
 138     } else {
 139         stw_be_p(&bd->flags, bd->flags);
 140         stw_be_p(&bd->length, bd->length);
 141         stl_be_p(&bd->bufptr, bd->bufptr);
 142     }
 143
 144     RING_DEBUG("Write Buffer Descriptor @ 0x" HWADDR_FMT_plx"\n", addr);
 145     cpu_physical_memory_write(addr,
 146                               bd,
 147                               sizeof(eTSEC_rxtx_bd));
 148 }
 149
 150 static void ievent_set(eTSEC    *etsec,
 151                        uint32_t  flags)
 152 {
 153     etsec->regs[IEVENT].value |= flags;
 154
 155     etsec_update_irq(etsec);
 156 }
 157
 158 static void tx_padding_and_crc(eTSEC *etsec, uint32_t min_frame_len)
 159 {
 160     int add = min_frame_len - etsec->tx_buffer_len;
 161
 162     /* Padding */
 163     if (add > 0) {
 164         RING_DEBUG("pad:%u\n", add);
 165         etsec->tx_buffer = g_realloc(etsec->tx_buffer,
 166                                         etsec->tx_buffer_len + add);
 167
 168         memset(etsec->tx_buffer + etsec->tx_buffer_len, 0x0, add);
 169         etsec->tx_buffer_len += add;
 170     }
 171
 172     /* Never add CRC in QEMU */
 173 }
 174
 175 static void process_tx_fcb(eTSEC *etsec)
 176 {
 177     uint8_t flags = (uint8_t)(*etsec->tx_buffer);
 178     /* L3 header offset from start of frame */
 179     uint8_t l3_header_offset = (uint8_t)*(etsec->tx_buffer + 3);
 180     /* L4 header offset from start of L3 header */
 181     uint8_t l4_header_offset = (uint8_t)*(etsec->tx_buffer + 2);
 182     /* L3 header */
 183     uint8_t *l3_header = etsec->tx_buffer + 8 + l3_header_offset;
 184     /* L4 header */
 185     uint8_t *l4_header = l3_header + l4_header_offset;
 186     int csum = 0;
 187
 188     /* if packet is IP4 and IP checksum is requested */
 189     if (flags & FCB_TX_IP && flags & FCB_TX_CIP) {
 190         csum |= CSUM_IP;
 191     }
 192     /* TODO Check the correct usage of the PHCS field of the FCB in case the NPH
 193      * flag is on */
 194
 195     /* if packet is IP4 and TCP or UDP */
 196     if (flags & FCB_TX_IP && flags & FCB_TX_TUP) {
 197         /* if UDP */
 198         if (flags & FCB_TX_UDP) {
 199             /* if checksum is requested */
 200             if (flags & FCB_TX_CTU) {
 201                 /* do UDP checksum */
 202                 csum |= CSUM_UDP;
 203             } else {
 204                 /* set checksum field to 0 */
 205                 l4_header[6] = 0;
 206                 l4_header[7] = 0;
 207             }
 208         } else if (flags & FCB_TX_CTU) { /* if TCP and checksum is requested */
 209             /* do TCP checksum */
 210             csum |= CSUM_TCP;
 211         }
 212     }
 213
 214     if (csum) {
 215         net_checksum_calculate(etsec->tx_buffer + 8,
 216                                etsec->tx_buffer_len - 8, csum);
 217     }
 218 }
 219
 220 static void process_tx_bd(eTSEC         *etsec,
 221                           eTSEC_rxtx_bd *bd)
 222 {
 223     uint8_t *tmp_buff = NULL;
 224     hwaddr tbdbth     = (hwaddr)(etsec->regs[TBDBPH].value & 0xF) << 32;
 225
 226     if (bd->length == 0) {
 227         /* ERROR */
 228         return;
 229     }
 230
 231     if (etsec->tx_buffer_len == 0) {
 232         /* It's the first BD */
 233         etsec->first_bd = *bd;
 234     }
 235
 236     /* TODO: if TxBD[TOE/UN] skip the Tx Frame Control Block*/
 237
 238     /* Load this Data Buffer */
 239     etsec->tx_buffer = g_realloc(etsec->tx_buffer,
 240                                     etsec->tx_buffer_len + bd->length);
 241     tmp_buff = etsec->tx_buffer + etsec->tx_buffer_len;
 242     cpu_physical_memory_read(bd->bufptr + tbdbth, tmp_buff, bd->length);
 243
 244     /* Update buffer length */
 245     etsec->tx_buffer_len += bd->length;
 246
 247
 248     if (etsec->tx_buffer_len != 0 && (bd->flags & BD_LAST)) {
 249         if (etsec->regs[MACCFG1].value & MACCFG1_TX_EN) {
 250             /* MAC Transmit enabled */
 251
 252             /* Process offload Tx FCB */
 253             if (etsec->first_bd.flags & BD_TX_TOEUN) {
 254                 process_tx_fcb(etsec);
 255             }
 256
 257             if (etsec->first_bd.flags & BD_TX_PADCRC
 258                 || etsec->regs[MACCFG2].value & MACCFG2_PADCRC) {
 259
 260                 /* Padding and CRC (Padding implies CRC) */
 261                 tx_padding_and_crc(etsec, 60);
 262
 263             } else if (etsec->first_bd.flags & BD_TX_TC
 264                        || etsec->regs[MACCFG2].value & MACCFG2_CRC_EN) {
 265
 266                 /* Only CRC */
 267                 /* Never add CRC in QEMU */
 268             }
 269
 270 #if defined(HEX_DUMP)
 271             qemu_log("eTSEC Send packet size:%d\n", etsec->tx_buffer_len);
 272             qemu_hexdump(stderr, "", etsec->tx_buffer, etsec->tx_buffer_len);
 273 #endif  /* ETSEC_RING_DEBUG */
 274
 275             if (etsec->first_bd.flags & BD_TX_TOEUN) {
 276                 qemu_send_packet(qemu_get_queue(etsec->nic),
 277                         etsec->tx_buffer + 8,
 278                         etsec->tx_buffer_len - 8);
 279             } else {
 280                 qemu_send_packet(qemu_get_queue(etsec->nic),
 281                         etsec->tx_buffer,
 282                         etsec->tx_buffer_len);
 283             }
 284
 285         }
 286
 287         etsec->tx_buffer_len = 0;
 288
 289         if (bd->flags & BD_INTERRUPT) {
 290             ievent_set(etsec, IEVENT_TXF);
 291         }
 292     } else {
 293         if (bd->flags & BD_INTERRUPT) {
 294             ievent_set(etsec, IEVENT_TXB);
 295         }
 296     }
 297
 298     /* Update DB flags */
 299
 300     /* Clear Ready */
 301     bd->flags &= ~BD_TX_READY;
 302
 303     /* Clear Defer */
 304     bd->flags &= ~BD_TX_PREDEF;
 305
 306     /* Clear Late Collision */
 307     bd->flags &= ~BD_TX_HFELC;
 308
 309     /* Clear Retransmission Limit */
 310     bd->flags &= ~BD_TX_CFRL;
 311
 312     /* Clear Retry Count */
 313     bd->flags &= ~(BD_TX_RC_MASK << BD_TX_RC_OFFSET);
 314
 315     /* Clear Underrun */
 316     bd->flags &= ~BD_TX_TOEUN;
 317
 318     /* Clear Truncation */
 319     bd->flags &= ~BD_TX_TR;
 320 }
 321
 322 void etsec_walk_tx_ring(eTSEC *etsec, int ring_nbr)
 323 {
 324     hwaddr        ring_base = 0;
 325     hwaddr        bd_addr   = 0;
 326     eTSEC_rxtx_bd bd;
 327     uint16_t      bd_flags;
 328
 329     if (!(etsec->regs[MACCFG1].value & MACCFG1_TX_EN)) {
 330         RING_DEBUG("%s: MAC Transmit not enabled\n", __func__);
 331         return;
 332     }
 333
 334     ring_base = (hwaddr)(etsec->regs[TBASEH].value & 0xF) << 32;
 335     ring_base += etsec->regs[TBASE0 + ring_nbr].value & ~0x7;
 336     bd_addr    = etsec->regs[TBPTR0 + ring_nbr].value & ~0x7;
 337
 338     do {
 339         read_buffer_descriptor(etsec, bd_addr, &bd);
 340
 341 #ifdef DEBUG_BD
 342         print_bd(bd,
 343                  eTSEC_TRANSMIT,
 344                  (bd_addr - ring_base) / sizeof(eTSEC_rxtx_bd));
 345
 346 #endif  /* DEBUG_BD */
 347
 348         /* Save flags before BD update */
 349         bd_flags = bd.flags;
 350
 351         if (!(bd_flags & BD_TX_READY)) {
 352             break;
 353         }
 354
 355         process_tx_bd(etsec, &bd);
 356         /* Write back BD after update */
 357         write_buffer_descriptor(etsec, bd_addr, &bd);
 358
 359         /* Wrap or next BD */
 360         if (bd_flags & BD_WRAP) {
 361             bd_addr = ring_base;
 362         } else {
 363             bd_addr += sizeof(eTSEC_rxtx_bd);
 364         }
 365     } while (TRUE);
 366
 367     /* Save the Buffer Descriptor Pointers to last bd that was not
 368      * succesfully closed */
 369     etsec->regs[TBPTR0 + ring_nbr].value = bd_addr;
 370
 371     /* Set transmit halt THLTx */
 372     etsec->regs[TSTAT].value |= 1 << (31 - ring_nbr);
 373 }
 374
 375 static void fill_rx_bd(eTSEC          *etsec,
 376                        eTSEC_rxtx_bd  *bd,
 377                        const uint8_t **buf,
 378                        size_t         *size)
 379 {
 380     uint16_t to_write;
 381     hwaddr   bufptr = bd->bufptr +
 382         ((hwaddr)(etsec->regs[TBDBPH].value & 0xF) << 32);
 383     uint8_t  padd[etsec->rx_padding];
 384     uint8_t  rem;
 385
 386     RING_DEBUG("eTSEC fill Rx buffer @ 0x%016" HWADDR_PRIx
 387                " size:%zu(padding + crc:%u) + fcb:%u\n",
 388                bufptr, *size, etsec->rx_padding, etsec->rx_fcb_size);
 389
 390     bd->length = 0;
 391
 392     /* This operation will only write FCB */
 393     if (etsec->rx_fcb_size != 0) {
 394
 395         cpu_physical_memory_write(bufptr, etsec->rx_fcb, etsec->rx_fcb_size);
 396
 397         bufptr             += etsec->rx_fcb_size;
 398         bd->length         += etsec->rx_fcb_size;
 399         etsec->rx_fcb_size  = 0;
 400
 401     }
 402
 403     /* We remove padding from the computation of to_write because it is not
 404      * allocated in the buffer.
 405      */
 406     to_write = MIN(*size - etsec->rx_padding,
 407                    etsec->regs[MRBLR].value - etsec->rx_fcb_size);
 408
 409     /* This operation can only write packet data and no padding */
 410     if (to_write > 0) {
 411         cpu_physical_memory_write(bufptr, *buf, to_write);
 412
 413         *buf   += to_write;
 414         bufptr += to_write;
 415         *size  -= to_write;
 416
 417         bd->flags  &= ~BD_RX_EMPTY;
 418         bd->length += to_write;
 419     }
 420
 421     if (*size == etsec->rx_padding) {
 422         /* The remaining bytes are only for padding which is not actually
 423          * allocated in the data buffer.
 424          */
 425
 426         rem = MIN(etsec->regs[MRBLR].value - bd->length, etsec->rx_padding);
 427
 428         if (rem > 0) {
 429             memset(padd, 0x0, sizeof(padd));
 430             etsec->rx_padding -= rem;
 431             *size             -= rem;
 432             bd->length        += rem;
 433             cpu_physical_memory_write(bufptr, padd, rem);
 434         }
 435     }
 436 }
 437
 438 static void rx_init_frame(eTSEC *etsec, const uint8_t *buf, size_t size)
 439 {
 440     uint32_t fcb_size = 0;
 441     uint8_t  prsdep   = (etsec->regs[RCTRL].value >> RCTRL_PRSDEP_OFFSET)
 442         & RCTRL_PRSDEP_MASK;
 443
 444     if (prsdep != 0) {
 445         /* Prepend FCB (FCB size + RCTRL[PAL]) */
 446         fcb_size = 8 + ((etsec->regs[RCTRL].value >> 16) & 0x1F);
 447
 448         etsec->rx_fcb_size = fcb_size;
 449
 450         /* TODO: fill_FCB(etsec); */
 451         memset(etsec->rx_fcb, 0x0, sizeof(etsec->rx_fcb));
 452
 453     } else {
 454         etsec->rx_fcb_size = 0;
 455     }
 456
 457     g_free(etsec->rx_buffer);
 458
 459     /* Do not copy the frame for now */
 460     etsec->rx_buffer     = (uint8_t *)buf;
 461     etsec->rx_buffer_len = size;
 462
 463     /* CRC padding (We don't have to compute the CRC) */
 464     etsec->rx_padding = 4;
 465
 466     /*
 467      * Ensure that payload length + CRC length is at least 802.3
 468      * minimum MTU size bytes long (64)
 469      */
 470     if (etsec->rx_buffer_len < 60) {
 471         etsec->rx_padding += 60 - etsec->rx_buffer_len;
 472     }
 473
 474     etsec->rx_first_in_frame = 1;
 475     etsec->rx_remaining_data = etsec->rx_buffer_len;
 476     RING_DEBUG("%s: rx_buffer_len:%u rx_padding+crc:%u\n", __func__,
 477                etsec->rx_buffer_len, etsec->rx_padding);
 478 }
 479
 480 ssize_t etsec_rx_ring_write(eTSEC *etsec, const uint8_t *buf, size_t size)
 481 {
 482     int ring_nbr = 0;           /* Always use ring0 (no filer) */
 483
 484     if (etsec->rx_buffer_len != 0) {
 485         RING_DEBUG("%s: We can't receive now,"
 486                    " a buffer is already in the pipe\n", __func__);
 487         return 0;
 488     }
 489
 490     if (etsec->regs[RSTAT].value & 1 << (23 - ring_nbr)) {
 491         RING_DEBUG("%s: The ring is halted\n", __func__);
 492         return -1;
 493     }
 494
 495     if (etsec->regs[DMACTRL].value & DMACTRL_GRS) {
 496         RING_DEBUG("%s: Graceful receive stop\n", __func__);
 497         return -1;
 498     }
 499
 500     if (!(etsec->regs[MACCFG1].value & MACCFG1_RX_EN)) {
 501         RING_DEBUG("%s: MAC Receive not enabled\n", __func__);
 502         return -1;
 503     }
 504
 505     if (!(etsec->regs[RCTRL].value & RCTRL_RSF) && (size < 60)) {
 506         /* CRC is not in the packet yet, so short frame is below 60 bytes */
 507         RING_DEBUG("%s: Drop short frame\n", __func__);
 508         return -1;
 509     }
 510
 511     rx_init_frame(etsec, buf, size);
 512
 513     etsec_walk_rx_ring(etsec, ring_nbr);
 514
 515     return size;
 516 }
 517
 518 void etsec_walk_rx_ring(eTSEC *etsec, int ring_nbr)
 519 {
 520     hwaddr         ring_base     = 0;
 521     hwaddr         bd_addr       = 0;
 522     hwaddr         start_bd_addr = 0;
 523     eTSEC_rxtx_bd  bd;
 524     uint16_t       bd_flags;
 525     size_t         remaining_data;
 526     const uint8_t *buf;
 527     uint8_t       *tmp_buf;
 528     size_t         size;
 529
 530     if (etsec->rx_buffer_len == 0) {
 531         /* No frame to send */
 532         RING_DEBUG("No frame to send\n");
 533         return;
 534     }
 535
 536     remaining_data = etsec->rx_remaining_data + etsec->rx_padding;
 537     buf            = etsec->rx_buffer
 538         + (etsec->rx_buffer_len - etsec->rx_remaining_data);
 539     size           = etsec->rx_buffer_len + etsec->rx_padding;
 540
 541     ring_base = (hwaddr)(etsec->regs[RBASEH].value & 0xF) << 32;
 542     ring_base += etsec->regs[RBASE0 + ring_nbr].value & ~0x7;
 543     start_bd_addr  = bd_addr = etsec->regs[RBPTR0 + ring_nbr].value & ~0x7;
 544
 545     do {
 546         read_buffer_descriptor(etsec, bd_addr, &bd);
 547
 548 #ifdef DEBUG_BD
 549         print_bd(bd,
 550                  eTSEC_RECEIVE,
 551                  (bd_addr - ring_base) / sizeof(eTSEC_rxtx_bd));
 552
 553 #endif  /* DEBUG_BD */
 554
 555         /* Save flags before BD update */
 556         bd_flags = bd.flags;
 557
 558         if (bd_flags & BD_RX_EMPTY) {
 559             fill_rx_bd(etsec, &bd, &buf, &remaining_data);
 560
 561             if (etsec->rx_first_in_frame) {
 562                 bd.flags |= BD_RX_FIRST;
 563                 etsec->rx_first_in_frame = 0;
 564                 etsec->rx_first_bd = bd;
 565             }
 566
 567             /* Last in frame */
 568             if (remaining_data == 0) {
 569
 570                 /* Clear flags */
 571
 572                 bd.flags &= ~0x7ff;
 573
 574                 bd.flags |= BD_LAST;
 575
 576                 /* NOTE: non-octet aligned frame is impossible in qemu */
 577
 578                 if (size >= etsec->regs[MAXFRM].value) {
 579                     /* frame length violation */
 580                     qemu_log("%s frame length violation: size:%zu MAXFRM:%d\n",
 581                            __func__, size, etsec->regs[MAXFRM].value);
 582
 583                     bd.flags |= BD_RX_LG;
 584                 }
 585
 586                 if (size  < 64) {
 587                     /* Short frame */
 588                     bd.flags |= BD_RX_SH;
 589                 }
 590
 591                 /* TODO: Broadcast and Multicast */
 592
 593                 if (bd.flags & BD_INTERRUPT) {
 594                     /* Set RXFx */
 595                     etsec->regs[RSTAT].value |= 1 << (7 - ring_nbr);
 596
 597                     /* Set IEVENT */
 598                     ievent_set(etsec, IEVENT_RXF);
 599                 }
 600
 601             } else {
 602                 if (bd.flags & BD_INTERRUPT) {
 603                     /* Set IEVENT */
 604                     ievent_set(etsec, IEVENT_RXB);
 605                 }
 606             }
 607
 608             /* Write back BD after update */
 609             write_buffer_descriptor(etsec, bd_addr, &bd);
 610         }
 611
 612         /* Wrap or next BD */
 613         if (bd_flags & BD_WRAP) {
 614             bd_addr = ring_base;
 615         } else {
 616             bd_addr += sizeof(eTSEC_rxtx_bd);
 617         }
 618     } while (remaining_data != 0
 619              && (bd_flags & BD_RX_EMPTY)
 620              && bd_addr != start_bd_addr);
 621
 622     /* Reset ring ptr */
 623     etsec->regs[RBPTR0 + ring_nbr].value = bd_addr;
 624
 625     /* The frame is too large to fit in the Rx ring */
 626     if (remaining_data > 0) {
 627
 628         /* Set RSTAT[QHLTx] */
 629         etsec->regs[RSTAT].value |= 1 << (23 - ring_nbr);
 630
 631         /* Save remaining data to send the end of the frame when the ring will
 632          * be restarted
 633          */
 634         etsec->rx_remaining_data = remaining_data;
 635
 636         /* Copy the frame */
 637         tmp_buf = g_malloc(size);
 638         memcpy(tmp_buf, etsec->rx_buffer, size);
 639         etsec->rx_buffer = tmp_buf;
 640
 641         RING_DEBUG("no empty RxBD available any more\n");
 642     } else {
 643         etsec->rx_buffer_len = 0;
 644         etsec->rx_buffer     = NULL;
 645         if (etsec->need_flush) {
 646             qemu_flush_queued_packets(qemu_get_queue(etsec->nic));
 647         }
 648     }
 649
 650     RING_DEBUG("eTSEC End of ring_write: remaining_data:%zu\n", remaining_data);
 651 }