xref: /openbmc/qemu/hw/net/npcm7xx_emc.c (revision ffe98631)
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 /* For crc32 */
33 #include <zlib.h>
34 
35 #include "hw/irq.h"
36 #include "hw/qdev-clock.h"
37 #include "hw/qdev-properties.h"
38 #include "hw/net/npcm7xx_emc.h"
39 #include "net/eth.h"
40 #include "migration/vmstate.h"
41 #include "qemu/bitops.h"
42 #include "qemu/error-report.h"
43 #include "qemu/log.h"
44 #include "qemu/module.h"
45 #include "qemu/units.h"
46 #include "sysemu/dma.h"
47 #include "trace.h"
48 
49 #define CRC_LENGTH 4
50 
51 /*
52  * The maximum size of a (layer 2) ethernet frame as defined by 802.3.
53  * 1518 = 6(dest macaddr) + 6(src macaddr) + 2(proto) + 4(crc) + 1500(payload)
54  * This does not include an additional 4 for the vlan field (802.1q).
55  */
56 #define MAX_ETH_FRAME_SIZE 1518
57 
58 static const char *emc_reg_name(int regno)
59 {
60 #define REG(name) case REG_ ## name: return #name;
61     switch (regno) {
62     REG(CAMCMR)
63     REG(CAMEN)
64     REG(TXDLSA)
65     REG(RXDLSA)
66     REG(MCMDR)
67     REG(MIID)
68     REG(MIIDA)
69     REG(FFTCR)
70     REG(TSDR)
71     REG(RSDR)
72     REG(DMARFC)
73     REG(MIEN)
74     REG(MISTA)
75     REG(MGSTA)
76     REG(MPCNT)
77     REG(MRPC)
78     REG(MRPCC)
79     REG(MREPC)
80     REG(DMARFS)
81     REG(CTXDSA)
82     REG(CTXBSA)
83     REG(CRXDSA)
84     REG(CRXBSA)
85     case REG_CAMM_BASE + 0: return "CAM0M";
86     case REG_CAML_BASE + 0: return "CAM0L";
87     case REG_CAMM_BASE + 2 ... REG_CAMML_LAST:
88         /* Only CAM0 is supported, fold the others into something simple. */
89         if (regno & 1) {
90             return "CAM<n>L";
91         } else {
92             return "CAM<n>M";
93         }
94     default: return "UNKNOWN";
95     }
96 #undef REG
97 }
98 
99 static void emc_reset(NPCM7xxEMCState *emc)
100 {
101     trace_npcm7xx_emc_reset(emc->emc_num);
102 
103     memset(&emc->regs[0], 0, sizeof(emc->regs));
104 
105     /* These regs have non-zero reset values. */
106     emc->regs[REG_TXDLSA] = 0xfffffffc;
107     emc->regs[REG_RXDLSA] = 0xfffffffc;
108     emc->regs[REG_MIIDA] = 0x00900000;
109     emc->regs[REG_FFTCR] = 0x0101;
110     emc->regs[REG_DMARFC] = 0x0800;
111     emc->regs[REG_MPCNT] = 0x7fff;
112 
113     emc->tx_active = false;
114     emc->rx_active = false;
115 }
116 
117 static void npcm7xx_emc_reset(DeviceState *dev)
118 {
119     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
120     emc_reset(emc);
121 }
122 
123 static void emc_soft_reset(NPCM7xxEMCState *emc)
124 {
125     /*
126      * The docs say at least MCMDR.{LBK,OPMOD} bits are not changed during a
127      * soft reset, but does not go into further detail. For now, KISS.
128      */
129     uint32_t mcmdr = emc->regs[REG_MCMDR];
130     emc_reset(emc);
131     emc->regs[REG_MCMDR] = mcmdr & (REG_MCMDR_LBK | REG_MCMDR_OPMOD);
132 
133     qemu_set_irq(emc->tx_irq, 0);
134     qemu_set_irq(emc->rx_irq, 0);
135 }
136 
137 static void emc_set_link(NetClientState *nc)
138 {
139     /* Nothing to do yet. */
140 }
141 
142 /* MISTA.TXINTR is the union of the individual bits with their enables. */
143 static void emc_update_mista_txintr(NPCM7xxEMCState *emc)
144 {
145     /* Only look at the bits we support. */
146     uint32_t mask = (REG_MISTA_TXBERR |
147                      REG_MISTA_TDU |
148                      REG_MISTA_TXCP);
149     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
150         emc->regs[REG_MISTA] |= REG_MISTA_TXINTR;
151     } else {
152         emc->regs[REG_MISTA] &= ~REG_MISTA_TXINTR;
153     }
154 }
155 
156 /* MISTA.RXINTR is the union of the individual bits with their enables. */
157 static void emc_update_mista_rxintr(NPCM7xxEMCState *emc)
158 {
159     /* Only look at the bits we support. */
160     uint32_t mask = (REG_MISTA_RXBERR |
161                      REG_MISTA_RDU |
162                      REG_MISTA_RXGD);
163     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
164         emc->regs[REG_MISTA] |= REG_MISTA_RXINTR;
165     } else {
166         emc->regs[REG_MISTA] &= ~REG_MISTA_RXINTR;
167     }
168 }
169 
170 /* N.B. emc_update_mista_txintr must have already been called. */
171 static void emc_update_tx_irq(NPCM7xxEMCState *emc)
172 {
173     int level = !!(emc->regs[REG_MISTA] &
174                    emc->regs[REG_MIEN] &
175                    REG_MISTA_TXINTR);
176     trace_npcm7xx_emc_update_tx_irq(level);
177     qemu_set_irq(emc->tx_irq, level);
178 }
179 
180 /* N.B. emc_update_mista_rxintr must have already been called. */
181 static void emc_update_rx_irq(NPCM7xxEMCState *emc)
182 {
183     int level = !!(emc->regs[REG_MISTA] &
184                    emc->regs[REG_MIEN] &
185                    REG_MISTA_RXINTR);
186     trace_npcm7xx_emc_update_rx_irq(level);
187     qemu_set_irq(emc->rx_irq, level);
188 }
189 
190 /* Update IRQ states due to changes in MIEN,MISTA. */
191 static void emc_update_irq_from_reg_change(NPCM7xxEMCState *emc)
192 {
193     emc_update_mista_txintr(emc);
194     emc_update_tx_irq(emc);
195 
196     emc_update_mista_rxintr(emc);
197     emc_update_rx_irq(emc);
198 }
199 
200 static int emc_read_tx_desc(dma_addr_t addr, NPCM7xxEMCTxDesc *desc)
201 {
202     if (dma_memory_read(&address_space_memory, addr, desc,
203                         sizeof(*desc), MEMTXATTRS_UNSPECIFIED)) {
204         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read descriptor @ 0x%"
205                       HWADDR_PRIx "\n", __func__, addr);
206         return -1;
207     }
208     desc->flags = le32_to_cpu(desc->flags);
209     desc->txbsa = le32_to_cpu(desc->txbsa);
210     desc->status_and_length = le32_to_cpu(desc->status_and_length);
211     desc->ntxdsa = le32_to_cpu(desc->ntxdsa);
212     return 0;
213 }
214 
215 static int emc_write_tx_desc(const NPCM7xxEMCTxDesc *desc, dma_addr_t addr)
216 {
217     NPCM7xxEMCTxDesc le_desc;
218 
219     le_desc.flags = cpu_to_le32(desc->flags);
220     le_desc.txbsa = cpu_to_le32(desc->txbsa);
221     le_desc.status_and_length = cpu_to_le32(desc->status_and_length);
222     le_desc.ntxdsa = cpu_to_le32(desc->ntxdsa);
223     if (dma_memory_write(&address_space_memory, addr, &le_desc,
224                          sizeof(le_desc), MEMTXATTRS_UNSPECIFIED)) {
225         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to write descriptor @ 0x%"
226                       HWADDR_PRIx "\n", __func__, addr);
227         return -1;
228     }
229     return 0;
230 }
231 
232 static int emc_read_rx_desc(dma_addr_t addr, NPCM7xxEMCRxDesc *desc)
233 {
234     if (dma_memory_read(&address_space_memory, addr, desc,
235                         sizeof(*desc), MEMTXATTRS_UNSPECIFIED)) {
236         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read descriptor @ 0x%"
237                       HWADDR_PRIx "\n", __func__, addr);
238         return -1;
239     }
240     desc->status_and_length = le32_to_cpu(desc->status_and_length);
241     desc->rxbsa = le32_to_cpu(desc->rxbsa);
242     desc->reserved = le32_to_cpu(desc->reserved);
243     desc->nrxdsa = le32_to_cpu(desc->nrxdsa);
244     return 0;
245 }
246 
247 static int emc_write_rx_desc(const NPCM7xxEMCRxDesc *desc, dma_addr_t addr)
248 {
249     NPCM7xxEMCRxDesc le_desc;
250 
251     le_desc.status_and_length = cpu_to_le32(desc->status_and_length);
252     le_desc.rxbsa = cpu_to_le32(desc->rxbsa);
253     le_desc.reserved = cpu_to_le32(desc->reserved);
254     le_desc.nrxdsa = cpu_to_le32(desc->nrxdsa);
255     if (dma_memory_write(&address_space_memory, addr, &le_desc,
256                          sizeof(le_desc), MEMTXATTRS_UNSPECIFIED)) {
257         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to write descriptor @ 0x%"
258                       HWADDR_PRIx "\n", __func__, addr);
259         return -1;
260     }
261     return 0;
262 }
263 
264 static void emc_set_mista(NPCM7xxEMCState *emc, uint32_t flags)
265 {
266     trace_npcm7xx_emc_set_mista(flags);
267     emc->regs[REG_MISTA] |= flags;
268     if (extract32(flags, 16, 16)) {
269         emc_update_mista_txintr(emc);
270     }
271     if (extract32(flags, 0, 16)) {
272         emc_update_mista_rxintr(emc);
273     }
274 }
275 
276 static void emc_halt_tx(NPCM7xxEMCState *emc, uint32_t mista_flag)
277 {
278     emc->tx_active = false;
279     emc_set_mista(emc, mista_flag);
280 }
281 
282 static void emc_halt_rx(NPCM7xxEMCState *emc, uint32_t mista_flag)
283 {
284     emc->rx_active = false;
285     emc_set_mista(emc, mista_flag);
286 }
287 
288 static void emc_enable_rx_and_flush(NPCM7xxEMCState *emc)
289 {
290     emc->rx_active = true;
291     qemu_flush_queued_packets(qemu_get_queue(emc->nic));
292 }
293 
294 static void emc_set_next_tx_descriptor(NPCM7xxEMCState *emc,
295                                        const NPCM7xxEMCTxDesc *tx_desc,
296                                        uint32_t desc_addr)
297 {
298     /* Update the current descriptor, if only to reset the owner flag. */
299     if (emc_write_tx_desc(tx_desc, desc_addr)) {
300         /*
301          * We just read it so this shouldn't generally happen.
302          * Error already reported.
303          */
304         emc_set_mista(emc, REG_MISTA_TXBERR);
305     }
306     emc->regs[REG_CTXDSA] = TX_DESC_NTXDSA(tx_desc->ntxdsa);
307 }
308 
309 static void emc_set_next_rx_descriptor(NPCM7xxEMCState *emc,
310                                        const NPCM7xxEMCRxDesc *rx_desc,
311                                        uint32_t desc_addr)
312 {
313     /* Update the current descriptor, if only to reset the owner flag. */
314     if (emc_write_rx_desc(rx_desc, desc_addr)) {
315         /*
316          * We just read it so this shouldn't generally happen.
317          * Error already reported.
318          */
319         emc_set_mista(emc, REG_MISTA_RXBERR);
320     }
321     emc->regs[REG_CRXDSA] = RX_DESC_NRXDSA(rx_desc->nrxdsa);
322 }
323 
324 static void emc_try_send_next_packet(NPCM7xxEMCState *emc)
325 {
326     /* Working buffer for sending out packets. Most packets fit in this. */
327 #define TX_BUFFER_SIZE 2048
328     uint8_t tx_send_buffer[TX_BUFFER_SIZE];
329     uint32_t desc_addr = TX_DESC_NTXDSA(emc->regs[REG_CTXDSA]);
330     NPCM7xxEMCTxDesc tx_desc;
331     uint32_t next_buf_addr, length;
332     uint8_t *buf;
333     g_autofree uint8_t *malloced_buf = NULL;
334 
335     if (emc_read_tx_desc(desc_addr, &tx_desc)) {
336         /* Error reading descriptor, already reported. */
337         emc_halt_tx(emc, REG_MISTA_TXBERR);
338         emc_update_tx_irq(emc);
339         return;
340     }
341 
342     /* Nothing we can do if we don't own the descriptor. */
343     if (!(tx_desc.flags & TX_DESC_FLAG_OWNER_MASK)) {
344         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
345         emc_halt_tx(emc, REG_MISTA_TDU);
346         emc_update_tx_irq(emc);
347         return;
348      }
349 
350     /* Give the descriptor back regardless of what happens. */
351     tx_desc.flags &= ~TX_DESC_FLAG_OWNER_MASK;
352     tx_desc.status_and_length &= 0xffff;
353 
354     /*
355      * Despite the h/w documentation saying the tx buffer is word aligned,
356      * the linux driver does not word align the buffer. There is value in not
357      * aligning the buffer: See the description of NET_IP_ALIGN in linux
358      * kernel sources.
359      */
360     next_buf_addr = tx_desc.txbsa;
361     emc->regs[REG_CTXBSA] = next_buf_addr;
362     length = TX_DESC_PKT_LEN(tx_desc.status_and_length);
363     buf = &tx_send_buffer[0];
364 
365     if (length > sizeof(tx_send_buffer)) {
366         malloced_buf = g_malloc(length);
367         buf = malloced_buf;
368     }
369 
370     if (dma_memory_read(&address_space_memory, next_buf_addr, buf,
371                         length, MEMTXATTRS_UNSPECIFIED)) {
372         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read packet @ 0x%x\n",
373                       __func__, next_buf_addr);
374         emc_set_mista(emc, REG_MISTA_TXBERR);
375         emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
376         emc_update_tx_irq(emc);
377         trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
378         return;
379     }
380 
381     if ((tx_desc.flags & TX_DESC_FLAG_PADEN) && (length < MIN_PACKET_LENGTH)) {
382         memset(buf + length, 0, MIN_PACKET_LENGTH - length);
383         length = MIN_PACKET_LENGTH;
384     }
385 
386     /* N.B. emc_receive can get called here. */
387     qemu_send_packet(qemu_get_queue(emc->nic), buf, length);
388     trace_npcm7xx_emc_sent_packet(length);
389 
390     tx_desc.status_and_length |= TX_DESC_STATUS_TXCP;
391     if (tx_desc.flags & TX_DESC_FLAG_INTEN) {
392         emc_set_mista(emc, REG_MISTA_TXCP);
393     }
394     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_TXINTR) {
395         tx_desc.status_and_length |= TX_DESC_STATUS_TXINTR;
396     }
397 
398     emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
399     emc_update_tx_irq(emc);
400     trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
401 }
402 
403 static bool emc_can_receive(NetClientState *nc)
404 {
405     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
406 
407     bool can_receive = emc->rx_active;
408     trace_npcm7xx_emc_can_receive(can_receive);
409     return can_receive;
410 }
411 
412 /* If result is false then *fail_reason contains the reason. */
413 static bool emc_receive_filter1(NPCM7xxEMCState *emc, const uint8_t *buf,
414                                 size_t len, const char **fail_reason)
415 {
416     eth_pkt_types_e pkt_type = get_eth_packet_type(PKT_GET_ETH_HDR(buf));
417 
418     switch (pkt_type) {
419     case ETH_PKT_BCAST:
420         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
421             return true;
422         } else {
423             *fail_reason = "Broadcast packet disabled";
424             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_ABP);
425         }
426     case ETH_PKT_MCAST:
427         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
428             return true;
429         } else {
430             *fail_reason = "Multicast packet disabled";
431             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_AMP);
432         }
433     case ETH_PKT_UCAST: {
434         bool matches;
435         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_AUP) {
436             return true;
437         }
438         matches = ((emc->regs[REG_CAMCMR] & REG_CAMCMR_ECMP) &&
439                    /* We only support one CAM register, CAM0. */
440                    (emc->regs[REG_CAMEN] & (1 << 0)) &&
441                    memcmp(buf, emc->conf.macaddr.a, ETH_ALEN) == 0);
442         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
443             *fail_reason = "MACADDR matched, comparison complemented";
444             return !matches;
445         } else {
446             *fail_reason = "MACADDR didn't match";
447             return matches;
448         }
449     }
450     default:
451         g_assert_not_reached();
452     }
453 }
454 
455 static bool emc_receive_filter(NPCM7xxEMCState *emc, const uint8_t *buf,
456                                size_t len)
457 {
458     const char *fail_reason = NULL;
459     bool ok = emc_receive_filter1(emc, buf, len, &fail_reason);
460     if (!ok) {
461         trace_npcm7xx_emc_packet_filtered_out(fail_reason);
462     }
463     return ok;
464 }
465 
466 static ssize_t emc_receive(NetClientState *nc, const uint8_t *buf, size_t len1)
467 {
468     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
469     const uint32_t len = len1;
470     size_t max_frame_len;
471     bool long_frame;
472     uint32_t desc_addr;
473     NPCM7xxEMCRxDesc rx_desc;
474     uint32_t crc;
475     uint8_t *crc_ptr;
476     uint32_t buf_addr;
477 
478     trace_npcm7xx_emc_receiving_packet(len);
479 
480     if (!emc_can_receive(nc)) {
481         qemu_log_mask(LOG_GUEST_ERROR, "%s: Unexpected packet\n", __func__);
482         return -1;
483     }
484 
485     if (len < ETH_HLEN ||
486         /* Defensive programming: drop unsupportable large packets. */
487         len > 0xffff - CRC_LENGTH) {
488         qemu_log_mask(LOG_GUEST_ERROR, "%s: Dropped frame of %u bytes\n",
489                       __func__, len);
490         return len;
491     }
492 
493     /*
494      * DENI is set if EMC received the Length/Type field of the incoming
495      * packet, so it will be set regardless of what happens next.
496      */
497     emc_set_mista(emc, REG_MISTA_DENI);
498 
499     if (!emc_receive_filter(emc, buf, len)) {
500         emc_update_rx_irq(emc);
501         return len;
502     }
503 
504     /* Huge frames (> DMARFC) are dropped. */
505     max_frame_len = REG_DMARFC_RXMS(emc->regs[REG_DMARFC]);
506     if (len + CRC_LENGTH > max_frame_len) {
507         trace_npcm7xx_emc_packet_dropped(len);
508         emc_set_mista(emc, REG_MISTA_DFOI);
509         emc_update_rx_irq(emc);
510         return len;
511     }
512 
513     /*
514      * Long Frames (> MAX_ETH_FRAME_SIZE) are also dropped, unless MCMDR.ALP
515      * is set.
516      */
517     long_frame = false;
518     if (len + CRC_LENGTH > MAX_ETH_FRAME_SIZE) {
519         if (emc->regs[REG_MCMDR] & REG_MCMDR_ALP) {
520             long_frame = true;
521         } else {
522             trace_npcm7xx_emc_packet_dropped(len);
523             emc_set_mista(emc, REG_MISTA_PTLE);
524             emc_update_rx_irq(emc);
525             return len;
526         }
527     }
528 
529     desc_addr = RX_DESC_NRXDSA(emc->regs[REG_CRXDSA]);
530     if (emc_read_rx_desc(desc_addr, &rx_desc)) {
531         /* Error reading descriptor, already reported. */
532         emc_halt_rx(emc, REG_MISTA_RXBERR);
533         emc_update_rx_irq(emc);
534         return len;
535     }
536 
537     /* Nothing we can do if we don't own the descriptor. */
538     if (!(rx_desc.status_and_length & RX_DESC_STATUS_OWNER_MASK)) {
539         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
540         emc_halt_rx(emc, REG_MISTA_RDU);
541         emc_update_rx_irq(emc);
542         return len;
543     }
544 
545     crc = 0;
546     crc_ptr = (uint8_t *) &crc;
547     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
548         crc = cpu_to_be32(crc32(~0, buf, len));
549     }
550 
551     /* Give the descriptor back regardless of what happens. */
552     rx_desc.status_and_length &= ~RX_DESC_STATUS_OWNER_MASK;
553 
554     buf_addr = rx_desc.rxbsa;
555     emc->regs[REG_CRXBSA] = buf_addr;
556     if (dma_memory_write(&address_space_memory, buf_addr, buf,
557                          len, MEMTXATTRS_UNSPECIFIED) ||
558         (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC) &&
559          dma_memory_write(&address_space_memory, buf_addr + len,
560                           crc_ptr, 4, MEMTXATTRS_UNSPECIFIED))) {
561         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bus error writing packet\n",
562                       __func__);
563         emc_set_mista(emc, REG_MISTA_RXBERR);
564         emc_set_next_rx_descriptor(emc, &rx_desc, desc_addr);
565         emc_update_rx_irq(emc);
566         trace_npcm7xx_emc_rx_done(emc->regs[REG_CRXDSA]);
567         return len;
568     }
569 
570     trace_npcm7xx_emc_received_packet(len);
571 
572     /* Note: We've already verified len+4 <= 0xffff. */
573     rx_desc.status_and_length = len;
574     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
575         rx_desc.status_and_length += 4;
576     }
577     rx_desc.status_and_length |= RX_DESC_STATUS_RXGD;
578     emc_set_mista(emc, REG_MISTA_RXGD);
579 
580     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_RXINTR) {
581         rx_desc.status_and_length |= RX_DESC_STATUS_RXINTR;
582     }
583     if (long_frame) {
584         rx_desc.status_and_length |= RX_DESC_STATUS_PTLE;
585     }
586 
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 static uint64_t npcm7xx_emc_read(void *opaque, hwaddr offset, unsigned size)
594 {
595     NPCM7xxEMCState *emc = opaque;
596     uint32_t reg = offset / sizeof(uint32_t);
597     uint32_t result;
598 
599     if (reg >= NPCM7XX_NUM_EMC_REGS) {
600         qemu_log_mask(LOG_GUEST_ERROR,
601                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
602                       __func__, offset);
603         return 0;
604     }
605 
606     switch (reg) {
607     case REG_MIID:
608         /*
609          * We don't implement MII. For determinism, always return zero as
610          * writes record the last value written for debugging purposes.
611          */
612         qemu_log_mask(LOG_UNIMP, "%s: Read of MIID, returning 0\n", __func__);
613         result = 0;
614         break;
615     case REG_TSDR:
616     case REG_RSDR:
617         qemu_log_mask(LOG_GUEST_ERROR,
618                       "%s: Read of write-only reg, %s/%d\n",
619                       __func__, emc_reg_name(reg), reg);
620         return 0;
621     default:
622         result = emc->regs[reg];
623         break;
624     }
625 
626     trace_npcm7xx_emc_reg_read(emc->emc_num, result, emc_reg_name(reg), reg);
627     return result;
628 }
629 
630 static void npcm7xx_emc_write(void *opaque, hwaddr offset,
631                               uint64_t v, unsigned size)
632 {
633     NPCM7xxEMCState *emc = opaque;
634     uint32_t reg = offset / sizeof(uint32_t);
635     uint32_t value = v;
636 
637     g_assert(size == sizeof(uint32_t));
638 
639     if (reg >= NPCM7XX_NUM_EMC_REGS) {
640         qemu_log_mask(LOG_GUEST_ERROR,
641                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
642                       __func__, offset);
643         return;
644     }
645 
646     trace_npcm7xx_emc_reg_write(emc->emc_num, emc_reg_name(reg), reg, value);
647 
648     switch (reg) {
649     case REG_CAMCMR:
650         emc->regs[reg] = value;
651         break;
652     case REG_CAMEN:
653         /* Only CAM0 is supported, don't pretend otherwise. */
654         if (value & ~1) {
655             qemu_log_mask(LOG_GUEST_ERROR,
656                           "%s: Only CAM0 is supported, cannot enable others"
657                           ": 0x%x\n",
658                           __func__, value);
659         }
660         emc->regs[reg] = value & 1;
661         break;
662     case REG_CAMM_BASE + 0:
663         emc->regs[reg] = value;
664         emc->conf.macaddr.a[0] = value >> 24;
665         emc->conf.macaddr.a[1] = value >> 16;
666         emc->conf.macaddr.a[2] = value >> 8;
667         emc->conf.macaddr.a[3] = value >> 0;
668         break;
669     case REG_CAML_BASE + 0:
670         emc->regs[reg] = value;
671         emc->conf.macaddr.a[4] = value >> 24;
672         emc->conf.macaddr.a[5] = value >> 16;
673         break;
674     case REG_MCMDR: {
675         uint32_t prev;
676         if (value & REG_MCMDR_SWR) {
677             emc_soft_reset(emc);
678             /* On h/w the reset happens over multiple cycles. For now KISS. */
679             break;
680         }
681         prev = emc->regs[reg];
682         emc->regs[reg] = value;
683         /* Update tx state. */
684         if (!(prev & REG_MCMDR_TXON) &&
685             (value & REG_MCMDR_TXON)) {
686             emc->regs[REG_CTXDSA] = emc->regs[REG_TXDLSA];
687             /*
688              * Linux kernel turns TX on with CPU still holding descriptor,
689              * which suggests we should wait for a write to TSDR before trying
690              * to send a packet: so we don't send one here.
691              */
692         } else if ((prev & REG_MCMDR_TXON) &&
693                    !(value & REG_MCMDR_TXON)) {
694             emc->regs[REG_MGSTA] |= REG_MGSTA_TXHA;
695         }
696         if (!(value & REG_MCMDR_TXON)) {
697             emc_halt_tx(emc, 0);
698         }
699         /* Update rx state. */
700         if (!(prev & REG_MCMDR_RXON) &&
701             (value & REG_MCMDR_RXON)) {
702             emc->regs[REG_CRXDSA] = emc->regs[REG_RXDLSA];
703         } else if ((prev & REG_MCMDR_RXON) &&
704                    !(value & REG_MCMDR_RXON)) {
705             emc->regs[REG_MGSTA] |= REG_MGSTA_RXHA;
706         }
707         if (value & REG_MCMDR_RXON) {
708             emc_enable_rx_and_flush(emc);
709         } else {
710             emc_halt_rx(emc, 0);
711         }
712         break;
713     }
714     case REG_TXDLSA:
715     case REG_RXDLSA:
716     case REG_DMARFC:
717     case REG_MIID:
718         emc->regs[reg] = value;
719         break;
720     case REG_MIEN:
721         emc->regs[reg] = value;
722         emc_update_irq_from_reg_change(emc);
723         break;
724     case REG_MISTA:
725         /* Clear the bits that have 1 in "value". */
726         emc->regs[reg] &= ~value;
727         emc_update_irq_from_reg_change(emc);
728         break;
729     case REG_MGSTA:
730         /* Clear the bits that have 1 in "value". */
731         emc->regs[reg] &= ~value;
732         break;
733     case REG_TSDR:
734         if (emc->regs[REG_MCMDR] & REG_MCMDR_TXON) {
735             emc->tx_active = true;
736             /* Keep trying to send packets until we run out. */
737             while (emc->tx_active) {
738                 emc_try_send_next_packet(emc);
739             }
740         }
741         break;
742     case REG_RSDR:
743         if (emc->regs[REG_MCMDR] & REG_MCMDR_RXON) {
744             emc_enable_rx_and_flush(emc);
745         }
746         break;
747     case REG_MIIDA:
748         emc->regs[reg] = value & ~REG_MIIDA_BUSY;
749         break;
750     case REG_MRPC:
751     case REG_MRPCC:
752     case REG_MREPC:
753     case REG_CTXDSA:
754     case REG_CTXBSA:
755     case REG_CRXDSA:
756     case REG_CRXBSA:
757         qemu_log_mask(LOG_GUEST_ERROR,
758                       "%s: Write to read-only reg %s/%d\n",
759                       __func__, emc_reg_name(reg), reg);
760         break;
761     default:
762         qemu_log_mask(LOG_UNIMP, "%s: Write to unimplemented reg %s/%d\n",
763                       __func__, emc_reg_name(reg), reg);
764         break;
765     }
766 }
767 
768 static const struct MemoryRegionOps npcm7xx_emc_ops = {
769     .read = npcm7xx_emc_read,
770     .write = npcm7xx_emc_write,
771     .endianness = DEVICE_LITTLE_ENDIAN,
772     .valid = {
773         .min_access_size = 4,
774         .max_access_size = 4,
775         .unaligned = false,
776     },
777 };
778 
779 static void emc_cleanup(NetClientState *nc)
780 {
781     /* Nothing to do yet. */
782 }
783 
784 static NetClientInfo net_npcm7xx_emc_info = {
785     .type = NET_CLIENT_DRIVER_NIC,
786     .size = sizeof(NICState),
787     .can_receive = emc_can_receive,
788     .receive = emc_receive,
789     .cleanup = emc_cleanup,
790     .link_status_changed = emc_set_link,
791 };
792 
793 static void npcm7xx_emc_realize(DeviceState *dev, Error **errp)
794 {
795     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
796     SysBusDevice *sbd = SYS_BUS_DEVICE(emc);
797 
798     memory_region_init_io(&emc->iomem, OBJECT(emc), &npcm7xx_emc_ops, emc,
799                           TYPE_NPCM7XX_EMC, 4 * KiB);
800     sysbus_init_mmio(sbd, &emc->iomem);
801     sysbus_init_irq(sbd, &emc->tx_irq);
802     sysbus_init_irq(sbd, &emc->rx_irq);
803 
804     qemu_macaddr_default_if_unset(&emc->conf.macaddr);
805     emc->nic = qemu_new_nic(&net_npcm7xx_emc_info, &emc->conf,
806                             object_get_typename(OBJECT(dev)), dev->id, emc);
807     qemu_format_nic_info_str(qemu_get_queue(emc->nic), emc->conf.macaddr.a);
808 }
809 
810 static void npcm7xx_emc_unrealize(DeviceState *dev)
811 {
812     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
813 
814     qemu_del_nic(emc->nic);
815 }
816 
817 static const VMStateDescription vmstate_npcm7xx_emc = {
818     .name = TYPE_NPCM7XX_EMC,
819     .version_id = 0,
820     .minimum_version_id = 0,
821     .fields = (VMStateField[]) {
822         VMSTATE_UINT8(emc_num, NPCM7xxEMCState),
823         VMSTATE_UINT32_ARRAY(regs, NPCM7xxEMCState, NPCM7XX_NUM_EMC_REGS),
824         VMSTATE_BOOL(tx_active, NPCM7xxEMCState),
825         VMSTATE_BOOL(rx_active, NPCM7xxEMCState),
826         VMSTATE_END_OF_LIST(),
827     },
828 };
829 
830 static Property npcm7xx_emc_properties[] = {
831     DEFINE_NIC_PROPERTIES(NPCM7xxEMCState, conf),
832     DEFINE_PROP_END_OF_LIST(),
833 };
834 
835 static void npcm7xx_emc_class_init(ObjectClass *klass, void *data)
836 {
837     DeviceClass *dc = DEVICE_CLASS(klass);
838 
839     set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
840     dc->desc = "NPCM7xx EMC Controller";
841     dc->realize = npcm7xx_emc_realize;
842     dc->unrealize = npcm7xx_emc_unrealize;
843     dc->reset = npcm7xx_emc_reset;
844     dc->vmsd = &vmstate_npcm7xx_emc;
845     device_class_set_props(dc, npcm7xx_emc_properties);
846 }
847 
848 static const TypeInfo npcm7xx_emc_info = {
849     .name = TYPE_NPCM7XX_EMC,
850     .parent = TYPE_SYS_BUS_DEVICE,
851     .instance_size = sizeof(NPCM7xxEMCState),
852     .class_init = npcm7xx_emc_class_init,
853 };
854 
855 static void npcm7xx_emc_register_type(void)
856 {
857     type_register_static(&npcm7xx_emc_info);
858 }
859 
860 type_init(npcm7xx_emc_register_type)
861