qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
Log | Files | Refs | Submodules | LICENSE

npcm7xx_emc.c (27084B)


      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)