xref: /openbmc/qemu/hw/net/npcm7xx_emc.c (revision b88e0a57)
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 "qemu-common.h"
36 #include "hw/irq.h"
37 #include "hw/qdev-clock.h"
38 #include "hw/qdev-properties.h"
39 #include "hw/net/npcm7xx_emc.h"
40 #include "net/eth.h"
41 #include "migration/vmstate.h"
42 #include "qemu/bitops.h"
43 #include "qemu/error-report.h"
44 #include "qemu/log.h"
45 #include "qemu/module.h"
46 #include "qemu/units.h"
47 #include "sysemu/dma.h"
48 #include "trace.h"
49 
50 #define CRC_LENGTH 4
51 
52 /*
53  * The maximum size of a (layer 2) ethernet frame as defined by 802.3.
54  * 1518 = 6(dest macaddr) + 6(src macaddr) + 2(proto) + 4(crc) + 1500(payload)
55  * This does not include an additional 4 for the vlan field (802.1q).
56  */
57 #define MAX_ETH_FRAME_SIZE 1518
58 
59 static const char *emc_reg_name(int regno)
60 {
61 #define REG(name) case REG_ ## name: return #name;
62     switch (regno) {
63     REG(CAMCMR)
64     REG(CAMEN)
65     REG(TXDLSA)
66     REG(RXDLSA)
67     REG(MCMDR)
68     REG(MIID)
69     REG(MIIDA)
70     REG(FFTCR)
71     REG(TSDR)
72     REG(RSDR)
73     REG(DMARFC)
74     REG(MIEN)
75     REG(MISTA)
76     REG(MGSTA)
77     REG(MPCNT)
78     REG(MRPC)
79     REG(MRPCC)
80     REG(MREPC)
81     REG(DMARFS)
82     REG(CTXDSA)
83     REG(CTXBSA)
84     REG(CRXDSA)
85     REG(CRXBSA)
86     case REG_CAMM_BASE + 0: return "CAM0M";
87     case REG_CAML_BASE + 0: return "CAM0L";
88     case REG_CAMM_BASE + 2 ... REG_CAMML_LAST:
89         /* Only CAM0 is supported, fold the others into something simple. */
90         if (regno & 1) {
91             return "CAM<n>L";
92         } else {
93             return "CAM<n>M";
94         }
95     default: return "UNKNOWN";
96     }
97 #undef REG
98 }
99 
100 static void emc_reset(NPCM7xxEMCState *emc)
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 
118 static void npcm7xx_emc_reset(DeviceState *dev)
119 {
120     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
121     emc_reset(emc);
122 }
123 
124 static void emc_soft_reset(NPCM7xxEMCState *emc)
125 {
126     /*
127      * The docs say at least MCMDR.{LBK,OPMOD} bits are not changed during a
128      * soft reset, but does not go into further detail. For now, KISS.
129      */
130     uint32_t mcmdr = emc->regs[REG_MCMDR];
131     emc_reset(emc);
132     emc->regs[REG_MCMDR] = mcmdr & (REG_MCMDR_LBK | REG_MCMDR_OPMOD);
133 
134     qemu_set_irq(emc->tx_irq, 0);
135     qemu_set_irq(emc->rx_irq, 0);
136 }
137 
138 static void emc_set_link(NetClientState *nc)
139 {
140     /* Nothing to do yet. */
141 }
142 
143 /* MISTA.TXINTR is the union of the individual bits with their enables. */
144 static void emc_update_mista_txintr(NPCM7xxEMCState *emc)
145 {
146     /* Only look at the bits we support. */
147     uint32_t mask = (REG_MISTA_TXBERR |
148                      REG_MISTA_TDU |
149                      REG_MISTA_TXCP);
150     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
151         emc->regs[REG_MISTA] |= REG_MISTA_TXINTR;
152     } else {
153         emc->regs[REG_MISTA] &= ~REG_MISTA_TXINTR;
154     }
155 }
156 
157 /* MISTA.RXINTR is the union of the individual bits with their enables. */
158 static void emc_update_mista_rxintr(NPCM7xxEMCState *emc)
159 {
160     /* Only look at the bits we support. */
161     uint32_t mask = (REG_MISTA_RXBERR |
162                      REG_MISTA_RDU |
163                      REG_MISTA_RXGD);
164     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & mask) {
165         emc->regs[REG_MISTA] |= REG_MISTA_RXINTR;
166     } else {
167         emc->regs[REG_MISTA] &= ~REG_MISTA_RXINTR;
168     }
169 }
170 
171 /* N.B. emc_update_mista_txintr must have already been called. */
172 static void emc_update_tx_irq(NPCM7xxEMCState *emc)
173 {
174     int level = !!(emc->regs[REG_MISTA] &
175                    emc->regs[REG_MIEN] &
176                    REG_MISTA_TXINTR);
177     trace_npcm7xx_emc_update_tx_irq(level);
178     qemu_set_irq(emc->tx_irq, level);
179 }
180 
181 /* N.B. emc_update_mista_rxintr must have already been called. */
182 static void emc_update_rx_irq(NPCM7xxEMCState *emc)
183 {
184     int level = !!(emc->regs[REG_MISTA] &
185                    emc->regs[REG_MIEN] &
186                    REG_MISTA_RXINTR);
187     trace_npcm7xx_emc_update_rx_irq(level);
188     qemu_set_irq(emc->rx_irq, level);
189 }
190 
191 /* Update IRQ states due to changes in MIEN,MISTA. */
192 static void emc_update_irq_from_reg_change(NPCM7xxEMCState *emc)
193 {
194     emc_update_mista_txintr(emc);
195     emc_update_tx_irq(emc);
196 
197     emc_update_mista_rxintr(emc);
198     emc_update_rx_irq(emc);
199 }
200 
201 static int emc_read_tx_desc(dma_addr_t addr, NPCM7xxEMCTxDesc *desc)
202 {
203     if (dma_memory_read(&address_space_memory, addr, desc, sizeof(*desc))) {
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))) {
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, sizeof(*desc))) {
235         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read descriptor @ 0x%"
236                       HWADDR_PRIx "\n", __func__, addr);
237         return -1;
238     }
239     desc->status_and_length = le32_to_cpu(desc->status_and_length);
240     desc->rxbsa = le32_to_cpu(desc->rxbsa);
241     desc->reserved = le32_to_cpu(desc->reserved);
242     desc->nrxdsa = le32_to_cpu(desc->nrxdsa);
243     return 0;
244 }
245 
246 static int emc_write_rx_desc(const NPCM7xxEMCRxDesc *desc, dma_addr_t addr)
247 {
248     NPCM7xxEMCRxDesc le_desc;
249 
250     le_desc.status_and_length = cpu_to_le32(desc->status_and_length);
251     le_desc.rxbsa = cpu_to_le32(desc->rxbsa);
252     le_desc.reserved = cpu_to_le32(desc->reserved);
253     le_desc.nrxdsa = cpu_to_le32(desc->nrxdsa);
254     if (dma_memory_write(&address_space_memory, addr, &le_desc,
255                          sizeof(le_desc))) {
256         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to write descriptor @ 0x%"
257                       HWADDR_PRIx "\n", __func__, addr);
258         return -1;
259     }
260     return 0;
261 }
262 
263 static void emc_set_mista(NPCM7xxEMCState *emc, uint32_t flags)
264 {
265     trace_npcm7xx_emc_set_mista(flags);
266     emc->regs[REG_MISTA] |= flags;
267     if (extract32(flags, 16, 16)) {
268         emc_update_mista_txintr(emc);
269     }
270     if (extract32(flags, 0, 16)) {
271         emc_update_mista_rxintr(emc);
272     }
273 }
274 
275 static void emc_halt_tx(NPCM7xxEMCState *emc, uint32_t mista_flag)
276 {
277     emc->tx_active = false;
278     emc_set_mista(emc, mista_flag);
279 }
280 
281 static void emc_halt_rx(NPCM7xxEMCState *emc, uint32_t mista_flag)
282 {
283     emc->rx_active = false;
284     emc_set_mista(emc, mista_flag);
285 }
286 
287 static void emc_set_next_tx_descriptor(NPCM7xxEMCState *emc,
288                                        const NPCM7xxEMCTxDesc *tx_desc,
289                                        uint32_t desc_addr)
290 {
291     /* Update the current descriptor, if only to reset the owner flag. */
292     if (emc_write_tx_desc(tx_desc, desc_addr)) {
293         /*
294          * We just read it so this shouldn't generally happen.
295          * Error already reported.
296          */
297         emc_set_mista(emc, REG_MISTA_TXBERR);
298     }
299     emc->regs[REG_CTXDSA] = TX_DESC_NTXDSA(tx_desc->ntxdsa);
300 }
301 
302 static void emc_set_next_rx_descriptor(NPCM7xxEMCState *emc,
303                                        const NPCM7xxEMCRxDesc *rx_desc,
304                                        uint32_t desc_addr)
305 {
306     /* Update the current descriptor, if only to reset the owner flag. */
307     if (emc_write_rx_desc(rx_desc, desc_addr)) {
308         /*
309          * We just read it so this shouldn't generally happen.
310          * Error already reported.
311          */
312         emc_set_mista(emc, REG_MISTA_RXBERR);
313     }
314     emc->regs[REG_CRXDSA] = RX_DESC_NRXDSA(rx_desc->nrxdsa);
315 }
316 
317 static void emc_try_send_next_packet(NPCM7xxEMCState *emc)
318 {
319     /* Working buffer for sending out packets. Most packets fit in this. */
320 #define TX_BUFFER_SIZE 2048
321     uint8_t tx_send_buffer[TX_BUFFER_SIZE];
322     uint32_t desc_addr = TX_DESC_NTXDSA(emc->regs[REG_CTXDSA]);
323     NPCM7xxEMCTxDesc tx_desc;
324     uint32_t next_buf_addr, length;
325     uint8_t *buf;
326     g_autofree uint8_t *malloced_buf = NULL;
327 
328     if (emc_read_tx_desc(desc_addr, &tx_desc)) {
329         /* Error reading descriptor, already reported. */
330         emc_halt_tx(emc, REG_MISTA_TXBERR);
331         emc_update_tx_irq(emc);
332         return;
333     }
334 
335     /* Nothing we can do if we don't own the descriptor. */
336     if (!(tx_desc.flags & TX_DESC_FLAG_OWNER_MASK)) {
337         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
338         emc_halt_tx(emc, REG_MISTA_TDU);
339         emc_update_tx_irq(emc);
340         return;
341      }
342 
343     /* Give the descriptor back regardless of what happens. */
344     tx_desc.flags &= ~TX_DESC_FLAG_OWNER_MASK;
345     tx_desc.status_and_length &= 0xffff;
346 
347     /*
348      * Despite the h/w documentation saying the tx buffer is word aligned,
349      * the linux driver does not word align the buffer. There is value in not
350      * aligning the buffer: See the description of NET_IP_ALIGN in linux
351      * kernel sources.
352      */
353     next_buf_addr = tx_desc.txbsa;
354     emc->regs[REG_CTXBSA] = next_buf_addr;
355     length = TX_DESC_PKT_LEN(tx_desc.status_and_length);
356     buf = &tx_send_buffer[0];
357 
358     if (length > sizeof(tx_send_buffer)) {
359         malloced_buf = g_malloc(length);
360         buf = malloced_buf;
361     }
362 
363     if (dma_memory_read(&address_space_memory, next_buf_addr, buf, length)) {
364         qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read packet @ 0x%x\n",
365                       __func__, next_buf_addr);
366         emc_set_mista(emc, REG_MISTA_TXBERR);
367         emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
368         emc_update_tx_irq(emc);
369         trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
370         return;
371     }
372 
373     if ((tx_desc.flags & TX_DESC_FLAG_PADEN) && (length < MIN_PACKET_LENGTH)) {
374         memset(buf + length, 0, MIN_PACKET_LENGTH - length);
375         length = MIN_PACKET_LENGTH;
376     }
377 
378     /* N.B. emc_receive can get called here. */
379     qemu_send_packet(qemu_get_queue(emc->nic), buf, length);
380     trace_npcm7xx_emc_sent_packet(length);
381 
382     tx_desc.status_and_length |= TX_DESC_STATUS_TXCP;
383     if (tx_desc.flags & TX_DESC_FLAG_INTEN) {
384         emc_set_mista(emc, REG_MISTA_TXCP);
385     }
386     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_TXINTR) {
387         tx_desc.status_and_length |= TX_DESC_STATUS_TXINTR;
388     }
389 
390     emc_set_next_tx_descriptor(emc, &tx_desc, desc_addr);
391     emc_update_tx_irq(emc);
392     trace_npcm7xx_emc_tx_done(emc->regs[REG_CTXDSA]);
393 }
394 
395 static bool emc_can_receive(NetClientState *nc)
396 {
397     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
398 
399     bool can_receive = emc->rx_active;
400     trace_npcm7xx_emc_can_receive(can_receive);
401     return can_receive;
402 }
403 
404 /* If result is false then *fail_reason contains the reason. */
405 static bool emc_receive_filter1(NPCM7xxEMCState *emc, const uint8_t *buf,
406                                 size_t len, const char **fail_reason)
407 {
408     eth_pkt_types_e pkt_type = get_eth_packet_type(PKT_GET_ETH_HDR(buf));
409 
410     switch (pkt_type) {
411     case ETH_PKT_BCAST:
412         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
413             return true;
414         } else {
415             *fail_reason = "Broadcast packet disabled";
416             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_ABP);
417         }
418     case ETH_PKT_MCAST:
419         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
420             return true;
421         } else {
422             *fail_reason = "Multicast packet disabled";
423             return !!(emc->regs[REG_CAMCMR] & REG_CAMCMR_AMP);
424         }
425     case ETH_PKT_UCAST: {
426         bool matches;
427         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_AUP) {
428             return true;
429         }
430         matches = ((emc->regs[REG_CAMCMR] & REG_CAMCMR_ECMP) &&
431                    /* We only support one CAM register, CAM0. */
432                    (emc->regs[REG_CAMEN] & (1 << 0)) &&
433                    memcmp(buf, emc->conf.macaddr.a, ETH_ALEN) == 0);
434         if (emc->regs[REG_CAMCMR] & REG_CAMCMR_CCAM) {
435             *fail_reason = "MACADDR matched, comparison complemented";
436             return !matches;
437         } else {
438             *fail_reason = "MACADDR didn't match";
439             return matches;
440         }
441     }
442     default:
443         g_assert_not_reached();
444     }
445 }
446 
447 static bool emc_receive_filter(NPCM7xxEMCState *emc, const uint8_t *buf,
448                                size_t len)
449 {
450     const char *fail_reason = NULL;
451     bool ok = emc_receive_filter1(emc, buf, len, &fail_reason);
452     if (!ok) {
453         trace_npcm7xx_emc_packet_filtered_out(fail_reason);
454     }
455     return ok;
456 }
457 
458 static ssize_t emc_receive(NetClientState *nc, const uint8_t *buf, size_t len1)
459 {
460     NPCM7xxEMCState *emc = NPCM7XX_EMC(qemu_get_nic_opaque(nc));
461     const uint32_t len = len1;
462     size_t max_frame_len;
463     bool long_frame;
464     uint32_t desc_addr;
465     NPCM7xxEMCRxDesc rx_desc;
466     uint32_t crc;
467     uint8_t *crc_ptr;
468     uint32_t buf_addr;
469 
470     trace_npcm7xx_emc_receiving_packet(len);
471 
472     if (!emc_can_receive(nc)) {
473         qemu_log_mask(LOG_GUEST_ERROR, "%s: Unexpected packet\n", __func__);
474         return -1;
475     }
476 
477     if (len < ETH_HLEN ||
478         /* Defensive programming: drop unsupportable large packets. */
479         len > 0xffff - CRC_LENGTH) {
480         qemu_log_mask(LOG_GUEST_ERROR, "%s: Dropped frame of %u bytes\n",
481                       __func__, len);
482         return len;
483     }
484 
485     /*
486      * DENI is set if EMC received the Length/Type field of the incoming
487      * packet, so it will be set regardless of what happens next.
488      */
489     emc_set_mista(emc, REG_MISTA_DENI);
490 
491     if (!emc_receive_filter(emc, buf, len)) {
492         emc_update_rx_irq(emc);
493         return len;
494     }
495 
496     /* Huge frames (> DMARFC) are dropped. */
497     max_frame_len = REG_DMARFC_RXMS(emc->regs[REG_DMARFC]);
498     if (len + CRC_LENGTH > max_frame_len) {
499         trace_npcm7xx_emc_packet_dropped(len);
500         emc_set_mista(emc, REG_MISTA_DFOI);
501         emc_update_rx_irq(emc);
502         return len;
503     }
504 
505     /*
506      * Long Frames (> MAX_ETH_FRAME_SIZE) are also dropped, unless MCMDR.ALP
507      * is set.
508      */
509     long_frame = false;
510     if (len + CRC_LENGTH > MAX_ETH_FRAME_SIZE) {
511         if (emc->regs[REG_MCMDR] & REG_MCMDR_ALP) {
512             long_frame = true;
513         } else {
514             trace_npcm7xx_emc_packet_dropped(len);
515             emc_set_mista(emc, REG_MISTA_PTLE);
516             emc_update_rx_irq(emc);
517             return len;
518         }
519     }
520 
521     desc_addr = RX_DESC_NRXDSA(emc->regs[REG_CRXDSA]);
522     if (emc_read_rx_desc(desc_addr, &rx_desc)) {
523         /* Error reading descriptor, already reported. */
524         emc_halt_rx(emc, REG_MISTA_RXBERR);
525         emc_update_rx_irq(emc);
526         return len;
527     }
528 
529     /* Nothing we can do if we don't own the descriptor. */
530     if (!(rx_desc.status_and_length & RX_DESC_STATUS_OWNER_MASK)) {
531         trace_npcm7xx_emc_cpu_owned_desc(desc_addr);
532         emc_halt_rx(emc, REG_MISTA_RDU);
533         emc_update_rx_irq(emc);
534         return len;
535     }
536 
537     crc = 0;
538     crc_ptr = (uint8_t *) &crc;
539     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
540         crc = cpu_to_be32(crc32(~0, buf, len));
541     }
542 
543     /* Give the descriptor back regardless of what happens. */
544     rx_desc.status_and_length &= ~RX_DESC_STATUS_OWNER_MASK;
545 
546     buf_addr = rx_desc.rxbsa;
547     emc->regs[REG_CRXBSA] = buf_addr;
548     if (dma_memory_write(&address_space_memory, buf_addr, buf, len) ||
549         (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC) &&
550          dma_memory_write(&address_space_memory, buf_addr + len, crc_ptr,
551                           4))) {
552         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bus error writing packet\n",
553                       __func__);
554         emc_set_mista(emc, REG_MISTA_RXBERR);
555         emc_set_next_rx_descriptor(emc, &rx_desc, desc_addr);
556         emc_update_rx_irq(emc);
557         trace_npcm7xx_emc_rx_done(emc->regs[REG_CRXDSA]);
558         return len;
559     }
560 
561     trace_npcm7xx_emc_received_packet(len);
562 
563     /* Note: We've already verified len+4 <= 0xffff. */
564     rx_desc.status_and_length = len;
565     if (!(emc->regs[REG_MCMDR] & REG_MCMDR_SPCRC)) {
566         rx_desc.status_and_length += 4;
567     }
568     rx_desc.status_and_length |= RX_DESC_STATUS_RXGD;
569     emc_set_mista(emc, REG_MISTA_RXGD);
570 
571     if (emc->regs[REG_MISTA] & emc->regs[REG_MIEN] & REG_MISTA_RXINTR) {
572         rx_desc.status_and_length |= RX_DESC_STATUS_RXINTR;
573     }
574     if (long_frame) {
575         rx_desc.status_and_length |= RX_DESC_STATUS_PTLE;
576     }
577 
578     emc_set_next_rx_descriptor(emc, &rx_desc, desc_addr);
579     emc_update_rx_irq(emc);
580     trace_npcm7xx_emc_rx_done(emc->regs[REG_CRXDSA]);
581     return len;
582 }
583 
584 static void emc_try_receive_next_packet(NPCM7xxEMCState *emc)
585 {
586     if (emc_can_receive(qemu_get_queue(emc->nic))) {
587         qemu_flush_queued_packets(qemu_get_queue(emc->nic));
588     }
589 }
590 
591 static uint64_t npcm7xx_emc_read(void *opaque, hwaddr offset, unsigned size)
592 {
593     NPCM7xxEMCState *emc = opaque;
594     uint32_t reg = offset / sizeof(uint32_t);
595     uint32_t result;
596 
597     if (reg >= NPCM7XX_NUM_EMC_REGS) {
598         qemu_log_mask(LOG_GUEST_ERROR,
599                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
600                       __func__, offset);
601         return 0;
602     }
603 
604     switch (reg) {
605     case REG_MIID:
606         /*
607          * We don't implement MII. For determinism, always return zero as
608          * writes record the last value written for debugging purposes.
609          */
610         qemu_log_mask(LOG_UNIMP, "%s: Read of MIID, returning 0\n", __func__);
611         result = 0;
612         break;
613     case REG_TSDR:
614     case REG_RSDR:
615         qemu_log_mask(LOG_GUEST_ERROR,
616                       "%s: Read of write-only reg, %s/%d\n",
617                       __func__, emc_reg_name(reg), reg);
618         return 0;
619     default:
620         result = emc->regs[reg];
621         break;
622     }
623 
624     trace_npcm7xx_emc_reg_read(emc->emc_num, result, emc_reg_name(reg), reg);
625     return result;
626 }
627 
628 static void npcm7xx_emc_write(void *opaque, hwaddr offset,
629                               uint64_t v, unsigned size)
630 {
631     NPCM7xxEMCState *emc = opaque;
632     uint32_t reg = offset / sizeof(uint32_t);
633     uint32_t value = v;
634 
635     g_assert(size == sizeof(uint32_t));
636 
637     if (reg >= NPCM7XX_NUM_EMC_REGS) {
638         qemu_log_mask(LOG_GUEST_ERROR,
639                       "%s: Invalid offset 0x%04" HWADDR_PRIx "\n",
640                       __func__, offset);
641         return;
642     }
643 
644     trace_npcm7xx_emc_reg_write(emc->emc_num, emc_reg_name(reg), reg, value);
645 
646     switch (reg) {
647     case REG_CAMCMR:
648         emc->regs[reg] = value;
649         break;
650     case REG_CAMEN:
651         /* Only CAM0 is supported, don't pretend otherwise. */
652         if (value & ~1) {
653             qemu_log_mask(LOG_GUEST_ERROR,
654                           "%s: Only CAM0 is supported, cannot enable others"
655                           ": 0x%x\n",
656                           __func__, value);
657         }
658         emc->regs[reg] = value & 1;
659         break;
660     case REG_CAMM_BASE + 0:
661         emc->regs[reg] = value;
662         emc->conf.macaddr.a[0] = value >> 24;
663         emc->conf.macaddr.a[1] = value >> 16;
664         emc->conf.macaddr.a[2] = value >> 8;
665         emc->conf.macaddr.a[3] = value >> 0;
666         break;
667     case REG_CAML_BASE + 0:
668         emc->regs[reg] = value;
669         emc->conf.macaddr.a[4] = value >> 24;
670         emc->conf.macaddr.a[5] = value >> 16;
671         break;
672     case REG_MCMDR: {
673         uint32_t prev;
674         if (value & REG_MCMDR_SWR) {
675             emc_soft_reset(emc);
676             /* On h/w the reset happens over multiple cycles. For now KISS. */
677             break;
678         }
679         prev = emc->regs[reg];
680         emc->regs[reg] = value;
681         /* Update tx state. */
682         if (!(prev & REG_MCMDR_TXON) &&
683             (value & REG_MCMDR_TXON)) {
684             emc->regs[REG_CTXDSA] = emc->regs[REG_TXDLSA];
685             /*
686              * Linux kernel turns TX on with CPU still holding descriptor,
687              * which suggests we should wait for a write to TSDR before trying
688              * to send a packet: so we don't send one here.
689              */
690         } else if ((prev & REG_MCMDR_TXON) &&
691                    !(value & REG_MCMDR_TXON)) {
692             emc->regs[REG_MGSTA] |= REG_MGSTA_TXHA;
693         }
694         if (!(value & REG_MCMDR_TXON)) {
695             emc_halt_tx(emc, 0);
696         }
697         /* Update rx state. */
698         if (!(prev & REG_MCMDR_RXON) &&
699             (value & REG_MCMDR_RXON)) {
700             emc->regs[REG_CRXDSA] = emc->regs[REG_RXDLSA];
701         } else if ((prev & REG_MCMDR_RXON) &&
702                    !(value & REG_MCMDR_RXON)) {
703             emc->regs[REG_MGSTA] |= REG_MGSTA_RXHA;
704         }
705         if (!(value & REG_MCMDR_RXON)) {
706             emc_halt_rx(emc, 0);
707         }
708         break;
709     }
710     case REG_TXDLSA:
711     case REG_RXDLSA:
712     case REG_DMARFC:
713     case REG_MIID:
714         emc->regs[reg] = value;
715         break;
716     case REG_MIEN:
717         emc->regs[reg] = value;
718         emc_update_irq_from_reg_change(emc);
719         break;
720     case REG_MISTA:
721         /* Clear the bits that have 1 in "value". */
722         emc->regs[reg] &= ~value;
723         emc_update_irq_from_reg_change(emc);
724         break;
725     case REG_MGSTA:
726         /* Clear the bits that have 1 in "value". */
727         emc->regs[reg] &= ~value;
728         break;
729     case REG_TSDR:
730         if (emc->regs[REG_MCMDR] & REG_MCMDR_TXON) {
731             emc->tx_active = true;
732             /* Keep trying to send packets until we run out. */
733             while (emc->tx_active) {
734                 emc_try_send_next_packet(emc);
735             }
736         }
737         break;
738     case REG_RSDR:
739         if (emc->regs[REG_MCMDR] & REG_MCMDR_RXON) {
740             emc->rx_active = true;
741             emc_try_receive_next_packet(emc);
742         }
743         break;
744     case REG_MIIDA:
745         emc->regs[reg] = value & ~REG_MIIDA_BUSY;
746         break;
747     case REG_MRPC:
748     case REG_MRPCC:
749     case REG_MREPC:
750     case REG_CTXDSA:
751     case REG_CTXBSA:
752     case REG_CRXDSA:
753     case REG_CRXBSA:
754         qemu_log_mask(LOG_GUEST_ERROR,
755                       "%s: Write to read-only reg %s/%d\n",
756                       __func__, emc_reg_name(reg), reg);
757         break;
758     default:
759         qemu_log_mask(LOG_UNIMP, "%s: Write to unimplemented reg %s/%d\n",
760                       __func__, emc_reg_name(reg), reg);
761         break;
762     }
763 }
764 
765 static const struct MemoryRegionOps npcm7xx_emc_ops = {
766     .read = npcm7xx_emc_read,
767     .write = npcm7xx_emc_write,
768     .endianness = DEVICE_LITTLE_ENDIAN,
769     .valid = {
770         .min_access_size = 4,
771         .max_access_size = 4,
772         .unaligned = false,
773     },
774 };
775 
776 static void emc_cleanup(NetClientState *nc)
777 {
778     /* Nothing to do yet. */
779 }
780 
781 static NetClientInfo net_npcm7xx_emc_info = {
782     .type = NET_CLIENT_DRIVER_NIC,
783     .size = sizeof(NICState),
784     .can_receive = emc_can_receive,
785     .receive = emc_receive,
786     .cleanup = emc_cleanup,
787     .link_status_changed = emc_set_link,
788 };
789 
790 static void npcm7xx_emc_realize(DeviceState *dev, Error **errp)
791 {
792     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
793     SysBusDevice *sbd = SYS_BUS_DEVICE(emc);
794 
795     memory_region_init_io(&emc->iomem, OBJECT(emc), &npcm7xx_emc_ops, emc,
796                           TYPE_NPCM7XX_EMC, 4 * KiB);
797     sysbus_init_mmio(sbd, &emc->iomem);
798     sysbus_init_irq(sbd, &emc->tx_irq);
799     sysbus_init_irq(sbd, &emc->rx_irq);
800 
801     qemu_macaddr_default_if_unset(&emc->conf.macaddr);
802     emc->nic = qemu_new_nic(&net_npcm7xx_emc_info, &emc->conf,
803                             object_get_typename(OBJECT(dev)), dev->id, emc);
804     qemu_format_nic_info_str(qemu_get_queue(emc->nic), emc->conf.macaddr.a);
805 }
806 
807 static void npcm7xx_emc_unrealize(DeviceState *dev)
808 {
809     NPCM7xxEMCState *emc = NPCM7XX_EMC(dev);
810 
811     qemu_del_nic(emc->nic);
812 }
813 
814 static const VMStateDescription vmstate_npcm7xx_emc = {
815     .name = TYPE_NPCM7XX_EMC,
816     .version_id = 0,
817     .minimum_version_id = 0,
818     .fields = (VMStateField[]) {
819         VMSTATE_UINT8(emc_num, NPCM7xxEMCState),
820         VMSTATE_UINT32_ARRAY(regs, NPCM7xxEMCState, NPCM7XX_NUM_EMC_REGS),
821         VMSTATE_BOOL(tx_active, NPCM7xxEMCState),
822         VMSTATE_BOOL(rx_active, NPCM7xxEMCState),
823         VMSTATE_END_OF_LIST(),
824     },
825 };
826 
827 static Property npcm7xx_emc_properties[] = {
828     DEFINE_NIC_PROPERTIES(NPCM7xxEMCState, conf),
829     DEFINE_PROP_END_OF_LIST(),
830 };
831 
832 static void npcm7xx_emc_class_init(ObjectClass *klass, void *data)
833 {
834     DeviceClass *dc = DEVICE_CLASS(klass);
835 
836     set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
837     dc->desc = "NPCM7xx EMC Controller";
838     dc->realize = npcm7xx_emc_realize;
839     dc->unrealize = npcm7xx_emc_unrealize;
840     dc->reset = npcm7xx_emc_reset;
841     dc->vmsd = &vmstate_npcm7xx_emc;
842     device_class_set_props(dc, npcm7xx_emc_properties);
843 }
844 
845 static const TypeInfo npcm7xx_emc_info = {
846     .name = TYPE_NPCM7XX_EMC,
847     .parent = TYPE_SYS_BUS_DEVICE,
848     .instance_size = sizeof(NPCM7xxEMCState),
849     .class_init = npcm7xx_emc_class_init,
850 };
851 
852 static void npcm7xx_emc_register_type(void)
853 {
854     type_register_static(&npcm7xx_emc_info);
855 }
856 
857 type_init(npcm7xx_emc_register_type)
858