xref: /openbmc/qemu/hw/net/npcm7xx_emc.c (revision 2e1cacfb)
1 /*
2  * Nuvoton NPCM7xx EMC Module
3  *
4  * Copyright 2020 Google LLC
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the
8  * Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14  * for more details.
15  *
16  * Unsupported/unimplemented features:
17  * - MCMDR.FDUP (full duplex) is ignored, half duplex is not supported
18  * - Only CAM0 is supported, CAM[1-15] are not
19  *   - writes to CAMEN.[1-15] are ignored, these bits always read as zeroes
20  * - MII is not implemented, MIIDA.BUSY and MIID always return zero
21  * - MCMDR.LBK is not implemented
22  * - MCMDR.{OPMOD,ENSQE,AEP,ARP} are not supported
23  * - H/W FIFOs are not supported, MCMDR.FFTCR is ignored
24  * - MGSTA.SQE is not supported
25  * - pause and control frames are not implemented
26  * - MGSTA.CCNT is not supported
27  * - MPCNT, DMARFS are not implemented
28  */
29 
30 #include "qemu/osdep.h"
31 
32 #include <zlib.h> /* for crc32 */
33 
34 #include "hw/irq.h"
35 #include "hw/qdev-clock.h"
36 #include "hw/qdev-properties.h"
37 #include "hw/net/npcm7xx_emc.h"
38 #include "net/eth.h"
39 #include "migration/vmstate.h"
40 #include "qemu/bitops.h"
41 #include "qemu/error-report.h"
42 #include "qemu/log.h"
43 #include "qemu/module.h"
44 #include "qemu/units.h"
45 #include "sysemu/dma.h"
46 #include "trace.h"
47 
48 #define CRC_LENGTH 4
49 
50 /*
51  * The maximum size of a (layer 2) ethernet frame as defined by 802.3.
52  * 1518 = 6(dest macaddr) + 6(src macaddr) + 2(proto) + 4(crc) + 1500(payload)
53  * This does not include an additional 4 for the vlan field (802.1q).
54  */
55 #define MAX_ETH_FRAME_SIZE 1518
56 
57 static const char *emc_reg_name(int regno)
58 {
59 #define REG(name) case REG_ ## name: return #name;
60     switch (regno) {
61     REG(CAMCMR)
62     REG(CAMEN)
63     REG(TXDLSA)
64     REG(RXDLSA)
65     REG(MCMDR)
66     REG(MIID)
67     REG(MIIDA)
68     REG(FFTCR)
69     REG(TSDR)
70     REG(RSDR)
71     REG(DMARFC)
72     REG(MIEN)
73     REG(MISTA)
74     REG(MGSTA)
75     REG(MPCNT)
76     REG(MRPC)
77     REG(MRPCC)
78     REG(MREPC)
79     REG(DMARFS)
80     REG(CTXDSA)
81     REG(CTXBSA)
82     REG(CRXDSA)
83     REG(CRXBSA)
84     case REG_CAMM_BASE + 0: return "CAM0M";
85     case REG_CAML_BASE + 0: return "CAM0L";
86     case REG_CAMM_BASE + 2 ... REG_CAMML_LAST:
87         /* Only CAM0 is supported, fold the others into something simple. */
88         if (regno & 1) {
89             return "CAM<n>L";
90         } else {
91             return "CAM<n>M";
92         }
93     default: return "UNKNOWN";
94     }
95 #undef REG
96 }
97 
98 static void emc_reset(NPCM7xxEMCState *emc)
99 {
100     uint32_t value;
101 
102     trace_npcm7xx_emc_reset(emc->emc_num);
103 
104     memset(&emc->regs[0], 0, sizeof(emc->regs));
105 
106     /* These regs have non-zero reset values. */
107     emc->regs[REG_TXDLSA] = 0xfffffffc;
108     emc->regs[REG_RXDLSA] = 0xfffffffc;
109     emc->regs[REG_MIIDA] = 0x00900000;
110     emc->regs[REG_FFTCR] = 0x0101;
111     emc->regs[REG_DMARFC] = 0x0800;
112     emc->regs[REG_MPCNT] = 0x7fff;
113 
114     emc->tx_active = false;
115     emc->rx_active = false;
116 
117     /* Set the MAC address in the register space. */
118     value = (emc->conf.macaddr.a[0] << 24) |
119         (emc->conf.macaddr.a[1] << 16) |
120         (emc->conf.macaddr.a[2] << 8) |
121         emc->conf.macaddr.a[3];
122     emc->regs[REG_CAMM_BASE] = value;
123 
124     value = (emc->conf.macaddr.a[4] << 24) | (emc->conf.macaddr.a[5] << 16);
125     emc->regs[REG_CAML_BASE] = value;
126 }
127 
128 static void npcm7xx_emc_reset(DeviceState *dev)
129 {
130     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
131     emc_reset(emc);
132 }
133 
134 static void emc_soft_reset(NPCM7xxEMCState *emc)
135 {
136     /*
137      * The docs say at least MCMDR.{LBK,OPMOD} bits are not changed during a
138      * soft reset, but does not go into further detail. For now, KISS.
139      */
140     uint32_t mcmdr = emc->regs[REG_MCMDR];
141     emc_reset(emc);
142     emc->regs[REG_MCMDR] = mcmdr & (REG_MCMDR_LBK | REG_MCMDR_OPMOD);
143 
144     qemu_set_irq(emc->tx_irq, 0);
145     qemu_set_irq(emc->rx_irq, 0);
146 }
147 
148 static void emc_set_link(NetClientState *nc)
149 {
150     /* Nothing to do yet. */
151 }
152 
153 /* MISTA.TXINTR is the union of the individual bits with their enables. */
154 static void emc_update_mista_txintr(NPCM7xxEMCState *emc)
155 {
156     /* Only look at the bits we support. */
157     uint32_t mask = (REG_MISTA_TXBERR |
158                      REG_MISTA_TDU |
159                      REG_MISTA_TXCP);
160     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
161         emc->regs[REG_MISTA] |= REG_MISTA_TXINTR;
162     } else {
163         emc->regs[REG_MISTA] &= ~REG_MISTA_TXINTR;
164     }
165 }
166 
167 /* MISTA.RXINTR is the union of the individual bits with their enables. */
168 static void emc_update_mista_rxintr(NPCM7xxEMCState *emc)
169 {
170     /* Only look at the bits we support. */
171     uint32_t mask = (REG_MISTA_RXBERR |
172                      REG_MISTA_RDU |
173                      REG_MISTA_RXGD);
174     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
175         emc->regs[REG_MISTA] |= REG_MISTA_RXINTR;
176     } else {
177         emc->regs[REG_MISTA] &= ~REG_MISTA_RXINTR;
178     }
179 }
180 
181 /* N.B. emc_update_mista_txintr must have already been called. */
182 static void emc_update_tx_irq(NPCM7xxEMCState *emc)
183 {
184     int level = !!(emc->regs[REG_MISTA] &
185                    emc->regs[REG_MIEN] &
186                    REG_MISTA_TXINTR);
187     trace_npcm7xx_emc_update_tx_irq(level);
188     qemu_set_irq(emc->tx_irq, level);
189 }
190 
191 /* N.B. emc_update_mista_rxintr must have already been called. */
192 static void emc_update_rx_irq(NPCM7xxEMCState *emc)
193 {
194     int level = !!(emc->regs[REG_MISTA] &
195                    emc->regs[REG_MIEN] &
196                    REG_MISTA_RXINTR);
197     trace_npcm7xx_emc_update_rx_irq(level);
198     qemu_set_irq(emc->rx_irq, level);
199 }
200 
201 /* Update IRQ states due to changes in MIEN,MISTA. */
202 static void emc_update_irq_from_reg_change(NPCM7xxEMCState *emc)
203 {
204     emc_update_mista_txintr(emc);
205     emc_update_tx_irq(emc);
206 
207     emc_update_mista_rxintr(emc);
208     emc_update_rx_irq(emc);
209 }
210 
211 static int emc_read_tx_desc(dma_addr_t addr, NPCM7xxEMCTxDesc *desc)
212 {
213     if (dma_memory_read(&address_space_memory, addr, desc,
214                         sizeof(*desc), MEMTXATTRS_UNSPECIFIED)) {
215         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read descriptor @ 0x%"
216                       HWADDR_PRIx "\n", __func__, addr);
217         return -1;
218     }
219     desc->flags = le32_to_cpu(desc->flags);
220     desc->txbsa = le32_to_cpu(desc->txbsa);
221     desc->status_and_length = le32_to_cpu(desc->status_and_length);
222     desc->ntxdsa = le32_to_cpu(desc->ntxdsa);
223     return 0;
224 }
225 
226 static int emc_write_tx_desc(const NPCM7xxEMCTxDesc *desc, dma_addr_t addr)
227 {
228     NPCM7xxEMCTxDesc le_desc;
229 
230     le_desc.flags = cpu_to_le32(desc->flags);
231     le_desc.txbsa = cpu_to_le32(desc->txbsa);
232     le_desc.status_and_length = cpu_to_le32(desc->status_and_length);
233     le_desc.ntxdsa = cpu_to_le32(desc->ntxdsa);
234     if (dma_memory_write(&address_space_memory, addr, &le_desc,
235                          sizeof(le_desc), MEMTXATTRS_UNSPECIFIED)) {
236         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to write descriptor @ 0x%"
237                       HWADDR_PRIx "\n", __func__, addr);
238         return -1;
239     }
240     return 0;
241 }
242 
243 static int emc_read_rx_desc(dma_addr_t addr, NPCM7xxEMCRxDesc *desc)
244 {
245     if (dma_memory_read(&address_space_memory, addr, desc,
246                         sizeof(*desc), MEMTXATTRS_UNSPECIFIED)) {
247         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read descriptor @ 0x%"
248                       HWADDR_PRIx "\n", __func__, addr);
249         return -1;
250     }
251     desc->status_and_length = le32_to_cpu(desc->status_and_length);
252     desc->rxbsa = le32_to_cpu(desc->rxbsa);
253     desc->reserved = le32_to_cpu(desc->reserved);
254     desc->nrxdsa = le32_to_cpu(desc->nrxdsa);
255     return 0;
256 }
257 
258 static int emc_write_rx_desc(const NPCM7xxEMCRxDesc *desc, dma_addr_t addr)
259 {
260     NPCM7xxEMCRxDesc le_desc;
261 
262     le_desc.status_and_length = cpu_to_le32(desc->status_and_length);
263     le_desc.rxbsa = cpu_to_le32(desc->rxbsa);
264     le_desc.reserved = cpu_to_le32(desc->reserved);
265     le_desc.nrxdsa = cpu_to_le32(desc->nrxdsa);
266     if (dma_memory_write(&address_space_memory, addr, &le_desc,
267                          sizeof(le_desc), MEMTXATTRS_UNSPECIFIED)) {
268         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to write descriptor @ 0x%"
269                       HWADDR_PRIx "\n", __func__, addr);
270         return -1;
271     }
272     return 0;
273 }
274 
275 static void emc_set_mista(NPCM7xxEMCState *emc, uint32_t flags)
276 {
277     trace_npcm7xx_emc_set_mista(flags);
278     emc->regs[REG_MISTA] |= flags;
279     if (extract32(flags, 16, 16)) {
280         emc_update_mista_txintr(emc);
281     }
282     if (extract32(flags, 0, 16)) {
283         emc_update_mista_rxintr(emc);
284     }
285 }
286 
287 static void emc_halt_tx(NPCM7xxEMCState *emc, uint32_t mista_flag)
288 {
289     emc->tx_active = false;
290     emc_set_mista(emc, mista_flag);
291 }
292 
293 static void emc_halt_rx(NPCM7xxEMCState *emc, uint32_t mista_flag)
294 {
295     emc->rx_active = false;
296     emc_set_mista(emc, mista_flag);
297 }
298 
299 static void emc_enable_rx_and_flush(NPCM7xxEMCState *emc)
300 {
301     emc->rx_active = true;
302     qemu_flush_queued_packets(qemu_get_queue(emc->nic));
303 }
304 
305 static void emc_set_next_tx_descriptor(NPCM7xxEMCState *emc,
306                                        const NPCM7xxEMCTxDesc *tx_desc,
307                                        uint32_t desc_addr)
308 {
309     /* Update the current descriptor, if only to reset the owner flag. */
310     if (emc_write_tx_desc(tx_desc, desc_addr)) {
311         /*
312          * We just read it so this shouldn't generally happen.
313          * Error already reported.
314          */
315         emc_set_mista(emc, REG_MISTA_TXBERR);
316     }
317     emc->regs[REG_CTXDSA] = TX_DESC_NTXDSA(tx_desc->ntxdsa);
318 }
319 
320 static void emc_set_next_rx_descriptor(NPCM7xxEMCState *emc,
321                                        const NPCM7xxEMCRxDesc *rx_desc,
322                                        uint32_t desc_addr)
323 {
324     /* Update the current descriptor, if only to reset the owner flag. */
325     if (emc_write_rx_desc(rx_desc, desc_addr)) {
326         /*
327          * We just read it so this shouldn't generally happen.
328          * Error already reported.
329          */
330         emc_set_mista(emc, REG_MISTA_RXBERR);
331     }
332     emc->regs[REG_CRXDSA] = RX_DESC_NRXDSA(rx_desc->nrxdsa);
333 }
334 
335 static void emc_try_send_next_packet(NPCM7xxEMCState *emc)
336 {
337     /* Working buffer for sending out packets. Most packets fit in this. */
338 #define TX_BUFFER_SIZE 2048
339     uint8_t tx_send_buffer[TX_BUFFER_SIZE];
340     uint32_t desc_addr = TX_DESC_NTXDSA(emc->regs[REG_CTXDSA]);
341     NPCM7xxEMCTxDesc tx_desc;
342     uint32_t next_buf_addr, length;
343     uint8_t *buf;
344     g_autofree uint8_t *malloced_buf = NULL;
345 
346     if (emc_read_tx_desc(desc_addr, &tx_desc)) {
347         /* Error reading descriptor, already reported. */
348         emc_halt_tx(emc, REG_MISTA_TXBERR);
349         emc_update_tx_irq(emc);
350         return;
351     }
352 
353     /* Nothing we can do if we don't own the descriptor. */
354     if (!(tx_desc.flags & TX_DESC_FLAG_OWNER_MASK)) {
355         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
356         emc_halt_tx(emc, REG_MISTA_TDU);
357         emc_update_tx_irq(emc);
358         return;
359      }
360 
361     /* Give the descriptor back regardless of what happens. */
362     tx_desc.flags &= ~TX_DESC_FLAG_OWNER_MASK;
363     tx_desc.status_and_length &= 0xffff;
364 
365     /*
366      * Despite the h/w documentation saying the tx buffer is word aligned,
367      * the linux driver does not word align the buffer. There is value in not
368      * aligning the buffer: See the description of NET_IP_ALIGN in linux
369      * kernel sources.
370      */
371     next_buf_addr = tx_desc.txbsa;
372     emc->regs[REG_CTXBSA] = next_buf_addr;
373     length = TX_DESC_PKT_LEN(tx_desc.status_and_length);
374     buf = &tx_send_buffer[0];
375 
376     if (length > sizeof(tx_send_buffer)) {
377         malloced_buf = g_malloc(length);
378         buf = malloced_buf;
379     }
380 
381     if (dma_memory_read(&address_space_memory, next_buf_addr, buf,
382                         length, MEMTXATTRS_UNSPECIFIED)) {
383         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read packet @ 0x%x\n",
384                       __func__, next_buf_addr);
385         emc_set_mista(emc, REG_MISTA_TXBERR);
386         emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
387         emc_update_tx_irq(emc);
388         trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
389         return;
390     }
391 
392     if ((tx_desc.flags & TX_DESC_FLAG_PADEN) && (length < MIN_PACKET_LENGTH)) {
393         memset(buf + length, 0, MIN_PACKET_LENGTH - length);
394         length = MIN_PACKET_LENGTH;
395     }
396 
397     /* N.B. emc_receive can get called here. */
398     qemu_send_packet(qemu_get_queue(emc->nic), buf, length);
399     trace_npcm7xx_emc_sent_packet(length);
400 
401     tx_desc.status_and_length |= TX_DESC_STATUS_TXCP;
402     if (tx_desc.flags & TX_DESC_FLAG_INTEN) {
403         emc_set_mista(emc, REG_MISTA_TXCP);
404     }
405     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_TXINTR) {
406         tx_desc.status_and_length |= TX_DESC_STATUS_TXINTR;
407     }
408 
409     emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
410     emc_update_tx_irq(emc);
411     trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
412 }
413 
414 static bool emc_can_receive(NetClientState *nc)
415 {
416     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
417 
418     bool can_receive = emc->rx_active;
419     trace_npcm7xx_emc_can_receive(can_receive);
420     return can_receive;
421 }
422 
423 /* If result is false then *fail_reason contains the reason. */
424 static bool emc_receive_filter1(NPCM7xxEMCState *emc, const uint8_t *buf,
425                                 size_t len, const char **fail_reason)
426 {
427     eth_pkt_types_e pkt_type = get_eth_packet_type(PKT_GET_ETH_HDR(buf));
428 
429     switch (pkt_type) {
430     case ETH_PKT_BCAST:
431         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
432             return true;
433         } else {
434             *fail_reason = "Broadcast packet disabled";
435             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_ABP);
436         }
437     case ETH_PKT_MCAST:
438         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
439             return true;
440         } else {
441             *fail_reason = "Multicast packet disabled";
442             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_AMP);
443         }
444     case ETH_PKT_UCAST: {
445         bool matches;
446         uint32_t value;
447         struct MACAddr mac;
448         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_AUP) {
449             return true;
450         }
451 
452         value = emc->regs[REG_CAMM_BASE];
453         mac.a[0] = value >> 24;
454         mac.a[1] = value >> 16;
455         mac.a[2] = value >> 8;
456         mac.a[3] = value >> 0;
457         value = emc->regs[REG_CAML_BASE];
458         mac.a[4] = value >> 24;
459         mac.a[5] = value >> 16;
460 
461         matches = ((emc->regs[REG_CAMCMR] & REG_CAMCMR_ECMP) &&
462                    /* We only support one CAM register, CAM0. */
463                    (emc->regs[REG_CAMEN] & (1 << 0)) &&
464                    memcmp(buf, mac.a, ETH_ALEN) == 0);
465         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
466             *fail_reason = "MACADDR matched, comparison complemented";
467             return !matches;
468         } else {
469             *fail_reason = "MACADDR didn't match";
470             return matches;
471         }
472     }
473     default:
474         g_assert_not_reached();
475     }
476 }
477 
478 static bool emc_receive_filter(NPCM7xxEMCState *emc, const uint8_t *buf,
479                                size_t len)
480 {
481     const char *fail_reason = NULL;
482     bool ok = emc_receive_filter1(emc, buf, len, &fail_reason);
483     if (!ok) {
484         trace_npcm7xx_emc_packet_filtered_out(fail_reason);
485     }
486     return ok;
487 }
488 
489 static ssize_t emc_receive(NetClientState *nc, const uint8_t *buf, size_t len1)
490 {
491     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
492     const uint32_t len = len1;
493     size_t max_frame_len;
494     bool long_frame;
495     uint32_t desc_addr;
496     NPCM7xxEMCRxDesc rx_desc;
497     uint32_t crc;
498     uint8_t *crc_ptr;
499     uint32_t buf_addr;
500 
501     trace_npcm7xx_emc_receiving_packet(len);
502 
503     if (!emc_can_receive(nc)) {
504         qemu_log_mask(LOG_GUEST_ERROR, "%s: Unexpected packet\n", __func__);
505         return -1;
506     }
507 
508     if (len < ETH_HLEN ||
509         /* Defensive programming: drop unsupportable large packets. */
510         len > 0xffff - CRC_LENGTH) {
511         qemu_log_mask(LOG_GUEST_ERROR, "%s: Dropped frame of %u bytes\n",
512                       __func__, len);
513         return len;
514     }
515 
516     /*
517      * DENI is set if EMC received the Length/Type field of the incoming
518      * packet, so it will be set regardless of what happens next.
519      */
520     emc_set_mista(emc, REG_MISTA_DENI);
521 
522     if (!emc_receive_filter(emc, buf, len)) {
523         emc_update_rx_irq(emc);
524         return len;
525     }
526 
527     /* Huge frames (> DMARFC) are dropped. */
528     max_frame_len = REG_DMARFC_RXMS(emc->regs[REG_DMARFC]);
529     if (len + CRC_LENGTH > max_frame_len) {
530         trace_npcm7xx_emc_packet_dropped(len);
531         emc_set_mista(emc, REG_MISTA_DFOI);
532         emc_update_rx_irq(emc);
533         return len;
534     }
535 
536     /*
537      * Long Frames (> MAX_ETH_FRAME_SIZE) are also dropped, unless MCMDR.ALP
538      * is set.
539      */
540     long_frame = false;
541     if (len + CRC_LENGTH > MAX_ETH_FRAME_SIZE) {
542         if (emc->regs[REG_MCMDR] & REG_MCMDR_ALP) {
543             long_frame = true;
544         } else {
545             trace_npcm7xx_emc_packet_dropped(len);
546             emc_set_mista(emc, REG_MISTA_PTLE);
547             emc_update_rx_irq(emc);
548             return len;
549         }
550     }
551 
552     desc_addr = RX_DESC_NRXDSA(emc->regs[REG_CRXDSA]);
553     if (emc_read_rx_desc(desc_addr, &rx_desc)) {
554         /* Error reading descriptor, already reported. */
555         emc_halt_rx(emc, REG_MISTA_RXBERR);
556         emc_update_rx_irq(emc);
557         return len;
558     }
559 
560     /* Nothing we can do if we don't own the descriptor. */
561     if (!(rx_desc.status_and_length & RX_DESC_STATUS_OWNER_MASK)) {
562         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
563         emc_halt_rx(emc, REG_MISTA_RDU);
564         emc_update_rx_irq(emc);
565         return len;
566     }
567 
568     crc = 0;
569     crc_ptr = (uint8_t *) &crc;
570     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
571         crc = cpu_to_be32(crc32(~0, buf, len));
572     }
573 
574     /* Give the descriptor back regardless of what happens. */
575     rx_desc.status_and_length &= ~RX_DESC_STATUS_OWNER_MASK;
576 
577     buf_addr = rx_desc.rxbsa;
578     emc->regs[REG_CRXBSA] = buf_addr;
579     if (dma_memory_write(&address_space_memory, buf_addr, buf,
580                          len, MEMTXATTRS_UNSPECIFIED) ||
581         (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC) &&
582          dma_memory_write(&address_space_memory, buf_addr + len,
583                           crc_ptr, 4, MEMTXATTRS_UNSPECIFIED))) {
584         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bus error writing packet\n",
585                       __func__);
586         emc_set_mista(emc, REG_MISTA_RXBERR);
587         emc_set_next_rx_descriptor(emc, &rx_desc, desc_addr);
588         emc_update_rx_irq(emc);
589         trace_npcm7xx_emc_rx_done(emc->regs[REG_CRXDSA]);
590         return len;
591     }
592 
593     trace_npcm7xx_emc_received_packet(len);
594 
595     /* Note: We've already verified len+4 <= 0xffff. */
596     rx_desc.status_and_length = len;
597     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
598         rx_desc.status_and_length += 4;
599     }
600     rx_desc.status_and_length |= RX_DESC_STATUS_RXGD;
601     emc_set_mista(emc, REG_MISTA_RXGD);
602 
603     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_RXINTR) {
604         rx_desc.status_and_length |= RX_DESC_STATUS_RXINTR;
605     }
606     if (long_frame) {
607         rx_desc.status_and_length |= RX_DESC_STATUS_PTLE;
608     }
609 
610     emc_set_next_rx_descriptor(emc, &rx_desc, desc_addr);
611     emc_update_rx_irq(emc);
612     trace_npcm7xx_emc_rx_done(emc->regs[REG_CRXDSA]);
613     return len;
614 }
615 
616 static uint64_t npcm7xx_emc_read(void *opaque, hwaddr offset, unsigned size)
617 {
618     NPCM7xxEMCState *emc = opaque;
619     uint32_t reg = offset / sizeof(uint32_t);
620     uint32_t result;
621 
622     if (reg >= NPCM7XX_NUM_EMC_REGS) {
623         qemu_log_mask(LOG_GUEST_ERROR,
624                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
625                       __func__, offset);
626         return 0;
627     }
628 
629     switch (reg) {
630     case REG_MIID:
631         /*
632          * We don't implement MII. For determinism, always return zero as
633          * writes record the last value written for debugging purposes.
634          */
635         qemu_log_mask(LOG_UNIMP, "%s: Read of MIID, returning 0\n", __func__);
636         result = 0;
637         break;
638     case REG_TSDR:
639     case REG_RSDR:
640         qemu_log_mask(LOG_GUEST_ERROR,
641                       "%s: Read of write-only reg, %s/%d\n",
642                       __func__, emc_reg_name(reg), reg);
643         return 0;
644     default:
645         result = emc->regs[reg];
646         break;
647     }
648 
649     trace_npcm7xx_emc_reg_read(emc->emc_num, result, emc_reg_name(reg), reg);
650     return result;
651 }
652 
653 static void npcm7xx_emc_write(void *opaque, hwaddr offset,
654                               uint64_t v, unsigned size)
655 {
656     NPCM7xxEMCState *emc = opaque;
657     uint32_t reg = offset / sizeof(uint32_t);
658     uint32_t value = v;
659 
660     g_assert(size == sizeof(uint32_t));
661 
662     if (reg >= NPCM7XX_NUM_EMC_REGS) {
663         qemu_log_mask(LOG_GUEST_ERROR,
664                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
665                       __func__, offset);
666         return;
667     }
668 
669     trace_npcm7xx_emc_reg_write(emc->emc_num, emc_reg_name(reg), reg, value);
670 
671     switch (reg) {
672     case REG_CAMCMR:
673         emc->regs[reg] = value;
674         break;
675     case REG_CAMEN:
676         /* Only CAM0 is supported, don't pretend otherwise. */
677         if (value & ~1) {
678             qemu_log_mask(LOG_GUEST_ERROR,
679                           "%s: Only CAM0 is supported, cannot enable others"
680                           ": 0x%x\n",
681                           __func__, value);
682         }
683         emc->regs[reg] = value & 1;
684         break;
685     case REG_CAMM_BASE + 0:
686         emc->regs[reg] = value;
687         break;
688     case REG_CAML_BASE + 0:
689         emc->regs[reg] = value;
690         break;
691     case REG_MCMDR: {
692         uint32_t prev;
693         if (value & REG_MCMDR_SWR) {
694             emc_soft_reset(emc);
695             /* On h/w the reset happens over multiple cycles. For now KISS. */
696             break;
697         }
698         prev = emc->regs[reg];
699         emc->regs[reg] = value;
700         /* Update tx state. */
701         if (!(prev & REG_MCMDR_TXON) &&
702             (value & REG_MCMDR_TXON)) {
703             emc->regs[REG_CTXDSA] = emc->regs[REG_TXDLSA];
704             /*
705              * Linux kernel turns TX on with CPU still holding descriptor,
706              * which suggests we should wait for a write to TSDR before trying
707              * to send a packet: so we don't send one here.
708              */
709         } else if ((prev & REG_MCMDR_TXON) &&
710                    !(value & REG_MCMDR_TXON)) {
711             emc->regs[REG_MGSTA] |= REG_MGSTA_TXHA;
712         }
713         if (!(value & REG_MCMDR_TXON)) {
714             emc_halt_tx(emc, 0);
715         }
716         /* Update rx state. */
717         if (!(prev & REG_MCMDR_RXON) &&
718             (value & REG_MCMDR_RXON)) {
719             emc->regs[REG_CRXDSA] = emc->regs[REG_RXDLSA];
720         } else if ((prev & REG_MCMDR_RXON) &&
721                    !(value & REG_MCMDR_RXON)) {
722             emc->regs[REG_MGSTA] |= REG_MGSTA_RXHA;
723         }
724         if (value & REG_MCMDR_RXON) {
725             emc_enable_rx_and_flush(emc);
726         } else {
727             emc_halt_rx(emc, 0);
728         }
729         break;
730     }
731     case REG_TXDLSA:
732     case REG_RXDLSA:
733     case REG_DMARFC:
734     case REG_MIID:
735         emc->regs[reg] = value;
736         break;
737     case REG_MIEN:
738         emc->regs[reg] = value;
739         emc_update_irq_from_reg_change(emc);
740         break;
741     case REG_MISTA:
742         /* Clear the bits that have 1 in "value". */
743         emc->regs[reg] &= ~value;
744         emc_update_irq_from_reg_change(emc);
745         break;
746     case REG_MGSTA:
747         /* Clear the bits that have 1 in "value". */
748         emc->regs[reg] &= ~value;
749         break;
750     case REG_TSDR:
751         if (emc->regs[REG_MCMDR] & REG_MCMDR_TXON) {
752             emc->tx_active = true;
753             /* Keep trying to send packets until we run out. */
754             while (emc->tx_active) {
755                 emc_try_send_next_packet(emc);
756             }
757         }
758         break;
759     case REG_RSDR:
760         if (emc->regs[REG_MCMDR] & REG_MCMDR_RXON) {
761             emc_enable_rx_and_flush(emc);
762         }
763         break;
764     case REG_MIIDA:
765         emc->regs[reg] = value & ~REG_MIIDA_BUSY;
766         break;
767     case REG_MRPC:
768     case REG_MRPCC:
769     case REG_MREPC:
770     case REG_CTXDSA:
771     case REG_CTXBSA:
772     case REG_CRXDSA:
773     case REG_CRXBSA:
774         qemu_log_mask(LOG_GUEST_ERROR,
775                       "%s: Write to read-only reg %s/%d\n",
776                       __func__, emc_reg_name(reg), reg);
777         break;
778     default:
779         qemu_log_mask(LOG_UNIMP, "%s: Write to unimplemented reg %s/%d\n",
780                       __func__, emc_reg_name(reg), reg);
781         break;
782     }
783 }
784 
785 static const struct MemoryRegionOps npcm7xx_emc_ops = {
786     .read = npcm7xx_emc_read,
787     .write = npcm7xx_emc_write,
788     .endianness = DEVICE_LITTLE_ENDIAN,
789     .valid = {
790         .min_access_size = 4,
791         .max_access_size = 4,
792         .unaligned = false,
793     },
794 };
795 
796 static void emc_cleanup(NetClientState *nc)
797 {
798     /* Nothing to do yet. */
799 }
800 
801 static NetClientInfo net_npcm7xx_emc_info = {
802     .type = NET_CLIENT_DRIVER_NIC,
803     .size = sizeof(NICState),
804     .can_receive = emc_can_receive,
805     .receive = emc_receive,
806     .cleanup = emc_cleanup,
807     .link_status_changed = emc_set_link,
808 };
809 
810 static void npcm7xx_emc_realize(DeviceState *dev, Error **errp)
811 {
812     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
813     SysBusDevice *sbd = SYS_BUS_DEVICE(emc);
814 
815     memory_region_init_io(&emc->iomem, OBJECT(emc), &npcm7xx_emc_ops, emc,
816                           TYPE_NPCM7XX_EMC, 4 * KiB);
817     sysbus_init_mmio(sbd, &emc->iomem);
818     sysbus_init_irq(sbd, &emc->tx_irq);
819     sysbus_init_irq(sbd, &emc->rx_irq);
820 
821     qemu_macaddr_default_if_unset(&emc->conf.macaddr);
822     emc->nic = qemu_new_nic(&net_npcm7xx_emc_info, &emc->conf,
823                             object_get_typename(OBJECT(dev)), dev->id,
824                             &dev->mem_reentrancy_guard, emc);
825     qemu_format_nic_info_str(qemu_get_queue(emc->nic), emc->conf.macaddr.a);
826 }
827 
828 static void npcm7xx_emc_unrealize(DeviceState *dev)
829 {
830     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
831 
832     qemu_del_nic(emc->nic);
833 }
834 
835 static const VMStateDescription vmstate_npcm7xx_emc = {
836     .name = TYPE_NPCM7XX_EMC,
837     .version_id = 0,
838     .minimum_version_id = 0,
839     .fields = (const VMStateField[]) {
840         VMSTATE_UINT8(emc_num, NPCM7xxEMCState),
841         VMSTATE_UINT32_ARRAY(regs, NPCM7xxEMCState, NPCM7XX_NUM_EMC_REGS),
842         VMSTATE_BOOL(tx_active, NPCM7xxEMCState),
843         VMSTATE_BOOL(rx_active, NPCM7xxEMCState),
844         VMSTATE_END_OF_LIST(),
845     },
846 };
847 
848 static Property npcm7xx_emc_properties[] = {
849     DEFINE_NIC_PROPERTIES(NPCM7xxEMCState, conf),
850     DEFINE_PROP_END_OF_LIST(),
851 };
852 
853 static void npcm7xx_emc_class_init(ObjectClass *klass, void *data)
854 {
855     DeviceClass *dc = DEVICE_CLASS(klass);
856 
857     set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
858     dc->desc = "NPCM7xx EMC Controller";
859     dc->realize = npcm7xx_emc_realize;
860     dc->unrealize = npcm7xx_emc_unrealize;
861     device_class_set_legacy_reset(dc, npcm7xx_emc_reset);
862     dc->vmsd = &vmstate_npcm7xx_emc;
863     device_class_set_props(dc, npcm7xx_emc_properties);
864 }
865 
866 static const TypeInfo npcm7xx_emc_info = {
867     .name = TYPE_NPCM7XX_EMC,
868     .parent = TYPE_SYS_BUS_DEVICE,
869     .instance_size = sizeof(NPCM7xxEMCState),
870     .class_init = npcm7xx_emc_class_init,
871 };
872 
873 static void npcm7xx_emc_register_type(void)
874 {
875     type_register_static(&npcm7xx_emc_info);
876 }
877 
878 type_init(npcm7xx_emc_register_type)
879