xref: /openbmc/qemu/hw/net/fsl_etsec/rings.c (revision a9ded601)
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" TARGET_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" TARGET_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     if ((flags & IEVENT_TXB && etsec->regs[IMASK].value & IMASK_TXBEN)
156         || (flags & IEVENT_TXF && etsec->regs[IMASK].value & IMASK_TXFEN)) {
157         qemu_irq_raise(etsec->tx_irq);
158         RING_DEBUG("%s Raise Tx IRQ\n", __func__);
159     }
160 
161     if ((flags & IEVENT_RXB && etsec->regs[IMASK].value & IMASK_RXBEN)
162         || (flags & IEVENT_RXF && etsec->regs[IMASK].value & IMASK_RXFEN)) {
163         qemu_irq_raise(etsec->rx_irq);
164         RING_DEBUG("%s Raise Rx IRQ\n", __func__);
165     }
166 }
167 
168 static void tx_padding_and_crc(eTSEC *etsec, uint32_t min_frame_len)
169 {
170     int add = min_frame_len - etsec->tx_buffer_len;
171 
172     /* Padding */
173     if (add > 0) {
174         RING_DEBUG("pad:%u\n", add);
175         etsec->tx_buffer = g_realloc(etsec->tx_buffer,
176                                         etsec->tx_buffer_len + add);
177 
178         memset(etsec->tx_buffer + etsec->tx_buffer_len, 0x0, add);
179         etsec->tx_buffer_len += add;
180     }
181 
182     /* Never add CRC in QEMU */
183 }
184 
185 static void process_tx_fcb(eTSEC *etsec)
186 {
187     uint8_t flags = (uint8_t)(*etsec->tx_buffer);
188     /* L3 header offset from start of frame */
189     uint8_t l3_header_offset = (uint8_t)*(etsec->tx_buffer + 3);
190     /* L4 header offset from start of L3 header */
191     uint8_t l4_header_offset = (uint8_t)*(etsec->tx_buffer + 2);
192     /* L3 header */
193     uint8_t *l3_header = etsec->tx_buffer + 8 + l3_header_offset;
194     /* L4 header */
195     uint8_t *l4_header = l3_header + l4_header_offset;
196 
197     /* if packet is IP4 and IP checksum is requested */
198     if (flags & FCB_TX_IP && flags & FCB_TX_CIP) {
199         /* do IP4 checksum (TODO This function does TCP/UDP checksum
200          * but not sure if it also does IP4 checksum.) */
201         net_checksum_calculate(etsec->tx_buffer + 8,
202                 etsec->tx_buffer_len - 8);
203     }
204     /* TODO Check the correct usage of the PHCS field of the FCB in case the NPH
205      * flag is on */
206 
207     /* if packet is IP4 and TCP or UDP */
208     if (flags & FCB_TX_IP && flags & FCB_TX_TUP) {
209         /* if UDP */
210         if (flags & FCB_TX_UDP) {
211             /* if checksum is requested */
212             if (flags & FCB_TX_CTU) {
213                 /* do UDP checksum */
214 
215                 net_checksum_calculate(etsec->tx_buffer + 8,
216                         etsec->tx_buffer_len - 8);
217             } else {
218                 /* set checksum field to 0 */
219                 l4_header[6] = 0;
220                 l4_header[7] = 0;
221             }
222         } else if (flags & FCB_TX_CTU) { /* if TCP and checksum is requested */
223             /* do TCP checksum */
224             net_checksum_calculate(etsec->tx_buffer + 8,
225                                    etsec->tx_buffer_len - 8);
226         }
227     }
228 }
229 
230 static void process_tx_bd(eTSEC         *etsec,
231                           eTSEC_rxtx_bd *bd)
232 {
233     uint8_t *tmp_buff = NULL;
234     hwaddr tbdbth     = (hwaddr)(etsec->regs[TBDBPH].value & 0xF) << 32;
235 
236     if (bd->length == 0) {
237         /* ERROR */
238         return;
239     }
240 
241     if (etsec->tx_buffer_len == 0) {
242         /* It's the first BD */
243         etsec->first_bd = *bd;
244     }
245 
246     /* TODO: if TxBD[TOE/UN] skip the Tx Frame Control Block*/
247 
248     /* Load this Data Buffer */
249     etsec->tx_buffer = g_realloc(etsec->tx_buffer,
250                                     etsec->tx_buffer_len + bd->length);
251     tmp_buff = etsec->tx_buffer + etsec->tx_buffer_len;
252     cpu_physical_memory_read(bd->bufptr + tbdbth, tmp_buff, bd->length);
253 
254     /* Update buffer length */
255     etsec->tx_buffer_len += bd->length;
256 
257 
258     if (etsec->tx_buffer_len != 0 && (bd->flags & BD_LAST)) {
259         if (etsec->regs[MACCFG1].value & MACCFG1_TX_EN) {
260             /* MAC Transmit enabled */
261 
262             /* Process offload Tx FCB */
263             if (etsec->first_bd.flags & BD_TX_TOEUN) {
264                 process_tx_fcb(etsec);
265             }
266 
267             if (etsec->first_bd.flags & BD_TX_PADCRC
268                 || etsec->regs[MACCFG2].value & MACCFG2_PADCRC) {
269 
270                 /* Padding and CRC (Padding implies CRC) */
271                 tx_padding_and_crc(etsec, 64);
272 
273             } else if (etsec->first_bd.flags & BD_TX_TC
274                        || etsec->regs[MACCFG2].value & MACCFG2_CRC_EN) {
275 
276                 /* Only CRC */
277                 /* Never add CRC in QEMU */
278             }
279 
280 #if defined(HEX_DUMP)
281             qemu_log("eTSEC Send packet size:%d\n", etsec->tx_buffer_len);
282             qemu_hexdump(etsec->tx_buffer, stderr, "", etsec->tx_buffer_len);
283 #endif  /* ETSEC_RING_DEBUG */
284 
285             if (etsec->first_bd.flags & BD_TX_TOEUN) {
286                 qemu_send_packet(qemu_get_queue(etsec->nic),
287                         etsec->tx_buffer + 8,
288                         etsec->tx_buffer_len - 8);
289             } else {
290                 qemu_send_packet(qemu_get_queue(etsec->nic),
291                         etsec->tx_buffer,
292                         etsec->tx_buffer_len);
293             }
294 
295         }
296 
297         etsec->tx_buffer_len = 0;
298 
299         if (bd->flags & BD_INTERRUPT) {
300             ievent_set(etsec, IEVENT_TXF);
301         }
302     } else {
303         if (bd->flags & BD_INTERRUPT) {
304             ievent_set(etsec, IEVENT_TXB);
305         }
306     }
307 
308     /* Update DB flags */
309 
310     /* Clear Ready */
311     bd->flags &= ~BD_TX_READY;
312 
313     /* Clear Defer */
314     bd->flags &= ~BD_TX_PREDEF;
315 
316     /* Clear Late Collision */
317     bd->flags &= ~BD_TX_HFELC;
318 
319     /* Clear Retransmission Limit */
320     bd->flags &= ~BD_TX_CFRL;
321 
322     /* Clear Retry Count */
323     bd->flags &= ~(BD_TX_RC_MASK << BD_TX_RC_OFFSET);
324 
325     /* Clear Underrun */
326     bd->flags &= ~BD_TX_TOEUN;
327 
328     /* Clear Truncation */
329     bd->flags &= ~BD_TX_TR;
330 }
331 
332 void etsec_walk_tx_ring(eTSEC *etsec, int ring_nbr)
333 {
334     hwaddr        ring_base = 0;
335     hwaddr        bd_addr   = 0;
336     eTSEC_rxtx_bd bd;
337     uint16_t      bd_flags;
338 
339     if (!(etsec->regs[MACCFG1].value & MACCFG1_TX_EN)) {
340         RING_DEBUG("%s: MAC Transmit not enabled\n", __func__);
341         return;
342     }
343 
344     ring_base = (hwaddr)(etsec->regs[TBASEH].value & 0xF) << 32;
345     ring_base += etsec->regs[TBASE0 + ring_nbr].value & ~0x7;
346     bd_addr    = etsec->regs[TBPTR0 + ring_nbr].value & ~0x7;
347 
348     do {
349         read_buffer_descriptor(etsec, bd_addr, &bd);
350 
351 #ifdef DEBUG_BD
352         print_bd(bd,
353                  eTSEC_TRANSMIT,
354                  (bd_addr - ring_base) / sizeof(eTSEC_rxtx_bd));
355 
356 #endif  /* DEBUG_BD */
357 
358         /* Save flags before BD update */
359         bd_flags = bd.flags;
360 
361         if (!(bd_flags & BD_TX_READY)) {
362             break;
363         }
364 
365         process_tx_bd(etsec, &bd);
366         /* Write back BD after update */
367         write_buffer_descriptor(etsec, bd_addr, &bd);
368 
369         /* Wrap or next BD */
370         if (bd_flags & BD_WRAP) {
371             bd_addr = ring_base;
372         } else {
373             bd_addr += sizeof(eTSEC_rxtx_bd);
374         }
375     } while (TRUE);
376 
377     /* Save the Buffer Descriptor Pointers to last bd that was not
378      * succesfully closed */
379     etsec->regs[TBPTR0 + ring_nbr].value = bd_addr;
380 
381     /* Set transmit halt THLTx */
382     etsec->regs[TSTAT].value |= 1 << (31 - ring_nbr);
383 }
384 
385 static void fill_rx_bd(eTSEC          *etsec,
386                        eTSEC_rxtx_bd  *bd,
387                        const uint8_t **buf,
388                        size_t         *size)
389 {
390     uint16_t to_write;
391     hwaddr   bufptr = bd->bufptr +
392         ((hwaddr)(etsec->regs[TBDBPH].value & 0xF) << 32);
393     uint8_t  padd[etsec->rx_padding];
394     uint8_t  rem;
395 
396     RING_DEBUG("eTSEC fill Rx buffer @ 0x%016" HWADDR_PRIx
397                " size:%zu(padding + crc:%u) + fcb:%u\n",
398                bufptr, *size, etsec->rx_padding, etsec->rx_fcb_size);
399 
400     bd->length = 0;
401 
402     /* This operation will only write FCB */
403     if (etsec->rx_fcb_size != 0) {
404 
405         cpu_physical_memory_write(bufptr, etsec->rx_fcb, etsec->rx_fcb_size);
406 
407         bufptr             += etsec->rx_fcb_size;
408         bd->length         += etsec->rx_fcb_size;
409         etsec->rx_fcb_size  = 0;
410 
411     }
412 
413     /* We remove padding from the computation of to_write because it is not
414      * allocated in the buffer.
415      */
416     to_write = MIN(*size - etsec->rx_padding,
417                    etsec->regs[MRBLR].value - etsec->rx_fcb_size);
418 
419     /* This operation can only write packet data and no padding */
420     if (to_write > 0) {
421         cpu_physical_memory_write(bufptr, *buf, to_write);
422 
423         *buf   += to_write;
424         bufptr += to_write;
425         *size  -= to_write;
426 
427         bd->flags  &= ~BD_RX_EMPTY;
428         bd->length += to_write;
429     }
430 
431     if (*size == etsec->rx_padding) {
432         /* The remaining bytes are only for padding which is not actually
433          * allocated in the data buffer.
434          */
435 
436         rem = MIN(etsec->regs[MRBLR].value - bd->length, etsec->rx_padding);
437 
438         if (rem > 0) {
439             memset(padd, 0x0, sizeof(padd));
440             etsec->rx_padding -= rem;
441             *size             -= rem;
442             bd->length        += rem;
443             cpu_physical_memory_write(bufptr, padd, rem);
444         }
445     }
446 }
447 
448 static void rx_init_frame(eTSEC *etsec, const uint8_t *buf, size_t size)
449 {
450     uint32_t fcb_size = 0;
451     uint8_t  prsdep   = (etsec->regs[RCTRL].value >> RCTRL_PRSDEP_OFFSET)
452         & RCTRL_PRSDEP_MASK;
453 
454     if (prsdep != 0) {
455         /* Prepend FCB (FCB size + RCTRL[PAL]) */
456         fcb_size = 8 + ((etsec->regs[RCTRL].value >> 16) & 0x1F);
457 
458         etsec->rx_fcb_size = fcb_size;
459 
460         /* TODO: fill_FCB(etsec); */
461         memset(etsec->rx_fcb, 0x0, sizeof(etsec->rx_fcb));
462 
463     } else {
464         etsec->rx_fcb_size = 0;
465     }
466 
467     g_free(etsec->rx_buffer);
468 
469     /* Do not copy the frame for now */
470     etsec->rx_buffer     = (uint8_t *)buf;
471     etsec->rx_buffer_len = size;
472 
473     /* CRC padding (We don't have to compute the CRC) */
474     etsec->rx_padding = 4;
475 
476     /*
477      * Ensure that payload length + CRC length is at least 802.3
478      * minimum MTU size bytes long (64)
479      */
480     if (etsec->rx_buffer_len < 60) {
481         etsec->rx_padding += 60 - etsec->rx_buffer_len;
482     }
483 
484     etsec->rx_first_in_frame = 1;
485     etsec->rx_remaining_data = etsec->rx_buffer_len;
486     RING_DEBUG("%s: rx_buffer_len:%u rx_padding+crc:%u\n", __func__,
487                etsec->rx_buffer_len, etsec->rx_padding);
488 }
489 
490 ssize_t etsec_rx_ring_write(eTSEC *etsec, const uint8_t *buf, size_t size)
491 {
492     int ring_nbr = 0;           /* Always use ring0 (no filer) */
493 
494     if (etsec->rx_buffer_len != 0) {
495         RING_DEBUG("%s: We can't receive now,"
496                    " a buffer is already in the pipe\n", __func__);
497         return 0;
498     }
499 
500     if (etsec->regs[RSTAT].value & 1 << (23 - ring_nbr)) {
501         RING_DEBUG("%s: The ring is halted\n", __func__);
502         return -1;
503     }
504 
505     if (etsec->regs[DMACTRL].value & DMACTRL_GRS) {
506         RING_DEBUG("%s: Graceful receive stop\n", __func__);
507         return -1;
508     }
509 
510     if (!(etsec->regs[MACCFG1].value & MACCFG1_RX_EN)) {
511         RING_DEBUG("%s: MAC Receive not enabled\n", __func__);
512         return -1;
513     }
514 
515     if ((etsec->regs[RCTRL].value & RCTRL_RSF) && (size < 60)) {
516         /* CRC is not in the packet yet, so short frame is below 60 bytes */
517         RING_DEBUG("%s: Drop short frame\n", __func__);
518         return -1;
519     }
520 
521     rx_init_frame(etsec, buf, size);
522 
523     etsec_walk_rx_ring(etsec, ring_nbr);
524 
525     return size;
526 }
527 
528 void etsec_walk_rx_ring(eTSEC *etsec, int ring_nbr)
529 {
530     hwaddr         ring_base     = 0;
531     hwaddr         bd_addr       = 0;
532     hwaddr         start_bd_addr = 0;
533     eTSEC_rxtx_bd  bd;
534     uint16_t       bd_flags;
535     size_t         remaining_data;
536     const uint8_t *buf;
537     uint8_t       *tmp_buf;
538     size_t         size;
539 
540     if (etsec->rx_buffer_len == 0) {
541         /* No frame to send */
542         RING_DEBUG("No frame to send\n");
543         return;
544     }
545 
546     remaining_data = etsec->rx_remaining_data + etsec->rx_padding;
547     buf            = etsec->rx_buffer
548         + (etsec->rx_buffer_len - etsec->rx_remaining_data);
549     size           = etsec->rx_buffer_len + etsec->rx_padding;
550 
551     ring_base = (hwaddr)(etsec->regs[RBASEH].value & 0xF) << 32;
552     ring_base += etsec->regs[RBASE0 + ring_nbr].value & ~0x7;
553     start_bd_addr  = bd_addr = etsec->regs[RBPTR0 + ring_nbr].value & ~0x7;
554 
555     do {
556         read_buffer_descriptor(etsec, bd_addr, &bd);
557 
558 #ifdef DEBUG_BD
559         print_bd(bd,
560                  eTSEC_RECEIVE,
561                  (bd_addr - ring_base) / sizeof(eTSEC_rxtx_bd));
562 
563 #endif  /* DEBUG_BD */
564 
565         /* Save flags before BD update */
566         bd_flags = bd.flags;
567 
568         if (bd_flags & BD_RX_EMPTY) {
569             fill_rx_bd(etsec, &bd, &buf, &remaining_data);
570 
571             if (etsec->rx_first_in_frame) {
572                 bd.flags |= BD_RX_FIRST;
573                 etsec->rx_first_in_frame = 0;
574                 etsec->rx_first_bd = bd;
575             }
576 
577             /* Last in frame */
578             if (remaining_data == 0) {
579 
580                 /* Clear flags */
581 
582                 bd.flags &= ~0x7ff;
583 
584                 bd.flags |= BD_LAST;
585 
586                 /* NOTE: non-octet aligned frame is impossible in qemu */
587 
588                 if (size >= etsec->regs[MAXFRM].value) {
589                     /* frame length violation */
590                     qemu_log("%s frame length violation: size:%zu MAXFRM:%d\n",
591                            __func__, size, etsec->regs[MAXFRM].value);
592 
593                     bd.flags |= BD_RX_LG;
594                 }
595 
596                 if (size  < 64) {
597                     /* Short frame */
598                     bd.flags |= BD_RX_SH;
599                 }
600 
601                 /* TODO: Broadcast and Multicast */
602 
603                 if (bd.flags & BD_INTERRUPT) {
604                     /* Set RXFx */
605                     etsec->regs[RSTAT].value |= 1 << (7 - ring_nbr);
606 
607                     /* Set IEVENT */
608                     ievent_set(etsec, IEVENT_RXF);
609                 }
610 
611             } else {
612                 if (bd.flags & BD_INTERRUPT) {
613                     /* Set IEVENT */
614                     ievent_set(etsec, IEVENT_RXB);
615                 }
616             }
617 
618             /* Write back BD after update */
619             write_buffer_descriptor(etsec, bd_addr, &bd);
620         }
621 
622         /* Wrap or next BD */
623         if (bd_flags & BD_WRAP) {
624             bd_addr = ring_base;
625         } else {
626             bd_addr += sizeof(eTSEC_rxtx_bd);
627         }
628     } while (remaining_data != 0
629              && (bd_flags & BD_RX_EMPTY)
630              && bd_addr != start_bd_addr);
631 
632     /* Reset ring ptr */
633     etsec->regs[RBPTR0 + ring_nbr].value = bd_addr;
634 
635     /* The frame is too large to fit in the Rx ring */
636     if (remaining_data > 0) {
637 
638         /* Set RSTAT[QHLTx] */
639         etsec->regs[RSTAT].value |= 1 << (23 - ring_nbr);
640 
641         /* Save remaining data to send the end of the frame when the ring will
642          * be restarted
643          */
644         etsec->rx_remaining_data = remaining_data;
645 
646         /* Copy the frame */
647         tmp_buf = g_malloc(size);
648         memcpy(tmp_buf, etsec->rx_buffer, size);
649         etsec->rx_buffer = tmp_buf;
650 
651         RING_DEBUG("no empty RxBD available any more\n");
652     } else {
653         etsec->rx_buffer_len = 0;
654         etsec->rx_buffer     = NULL;
655         if (etsec->need_flush) {
656             qemu_flush_queued_packets(qemu_get_queue(etsec->nic));
657         }
658     }
659 
660     RING_DEBUG("eTSEC End of ring_write: remaining_data:%zu\n", remaining_data);
661 }
662