drivers/net/mhi_net.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* MHI Network driver - Network over MHI bus
   3  *
   4  * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
   5  */
   6
   7 #include <linux/if_arp.h>
   8 #include <linux/mhi.h>
   9 #include <linux/mod_devicetable.h>
  10 #include <linux/module.h>
  11 #include <linux/netdevice.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/u64_stats_sync.h>
  14
  15 #define MHI_NET_MIN_MTU         ETH_MIN_MTU
  16 #define MHI_NET_MAX_MTU         0xffff
  17 #define MHI_NET_DEFAULT_MTU     0x4000
  18
  19 struct mhi_net_stats {
  20         u64_stats_t rx_packets;
  21         u64_stats_t rx_bytes;
  22         u64_stats_t rx_errors;
  23         u64_stats_t tx_packets;
  24         u64_stats_t tx_bytes;
  25         u64_stats_t tx_errors;
  26         u64_stats_t tx_dropped;
  27         struct u64_stats_sync tx_syncp;
  28         struct u64_stats_sync rx_syncp;
  29 };
  30
  31 struct mhi_net_dev {
  32         struct mhi_device *mdev;
  33         struct net_device *ndev;
  34         struct sk_buff *skbagg_head;
  35         struct sk_buff *skbagg_tail;
  36         struct delayed_work rx_refill;
  37         struct mhi_net_stats stats;
  38         u32 rx_queue_sz;
  39         int msg_enable;
  40         unsigned int mru;
  41 };
  42
  43 struct mhi_device_info {
  44         const char *netname;
  45 };
  46
  47 static int mhi_ndo_open(struct net_device *ndev)
  48 {
  49         struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  50
  51         /* Feed the rx buffer pool */
  52         schedule_delayed_work(&mhi_netdev->rx_refill, 0);
  53
  54         /* Carrier is established via out-of-band channel (e.g. qmi) */
  55         netif_carrier_on(ndev);
  56
  57         netif_start_queue(ndev);
  58
  59         return 0;
  60 }
  61
  62 static int mhi_ndo_stop(struct net_device *ndev)
  63 {
  64         struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  65
  66         netif_stop_queue(ndev);
  67         netif_carrier_off(ndev);
  68         cancel_delayed_work_sync(&mhi_netdev->rx_refill);
  69
  70         return 0;
  71 }
  72
  73 static netdev_tx_t mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
  74 {
  75         struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  76         struct mhi_device *mdev = mhi_netdev->mdev;
  77         int err;
  78
  79         err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
  80         if (unlikely(err)) {
  81                 net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
  82                                     ndev->name, err);
  83                 dev_kfree_skb_any(skb);
  84                 goto exit_drop;
  85         }
  86
  87         if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
  88                 netif_stop_queue(ndev);
  89
  90         return NETDEV_TX_OK;
  91
  92 exit_drop:
  93         u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
  94         u64_stats_inc(&mhi_netdev->stats.tx_dropped);
  95         u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
  96
  97         return NETDEV_TX_OK;
  98 }
  99
 100 static void mhi_ndo_get_stats64(struct net_device *ndev,
 101                                 struct rtnl_link_stats64 *stats)
 102 {
 103         struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
 104         unsigned int start;
 105
 106         do {
 107                 start = u64_stats_fetch_begin(&mhi_netdev->stats.rx_syncp);
 108                 stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
 109                 stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
 110                 stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
 111         } while (u64_stats_fetch_retry(&mhi_netdev->stats.rx_syncp, start));
 112
 113         do {
 114                 start = u64_stats_fetch_begin(&mhi_netdev->stats.tx_syncp);
 115                 stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
 116                 stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
 117                 stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
 118                 stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
 119         } while (u64_stats_fetch_retry(&mhi_netdev->stats.tx_syncp, start));
 120 }
 121
 122 static const struct net_device_ops mhi_netdev_ops = {
 123         .ndo_open               = mhi_ndo_open,
 124         .ndo_stop               = mhi_ndo_stop,
 125         .ndo_start_xmit         = mhi_ndo_xmit,
 126         .ndo_get_stats64        = mhi_ndo_get_stats64,
 127 };
 128
 129 static void mhi_net_setup(struct net_device *ndev)
 130 {
 131         ndev->header_ops = NULL;  /* No header */
 132         ndev->type = ARPHRD_RAWIP;
 133         ndev->hard_header_len = 0;
 134         ndev->addr_len = 0;
 135         ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
 136         ndev->netdev_ops = &mhi_netdev_ops;
 137         ndev->mtu = MHI_NET_DEFAULT_MTU;
 138         ndev->min_mtu = MHI_NET_MIN_MTU;
 139         ndev->max_mtu = MHI_NET_MAX_MTU;
 140         ndev->tx_queue_len = 1000;
 141 }
 142
 143 static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
 144                                        struct sk_buff *skb)
 145 {
 146         struct sk_buff *head = mhi_netdev->skbagg_head;
 147         struct sk_buff *tail = mhi_netdev->skbagg_tail;
 148
 149         /* This is non-paged skb chaining using frag_list */
 150         if (!head) {
 151                 mhi_netdev->skbagg_head = skb;
 152                 return skb;
 153         }
 154
 155         if (!skb_shinfo(head)->frag_list)
 156                 skb_shinfo(head)->frag_list = skb;
 157         else
 158                 tail->next = skb;
 159
 160         head->len += skb->len;
 161         head->data_len += skb->len;
 162         head->truesize += skb->truesize;
 163
 164         mhi_netdev->skbagg_tail = skb;
 165
 166         return mhi_netdev->skbagg_head;
 167 }
 168
 169 static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
 170                                 struct mhi_result *mhi_res)
 171 {
 172         struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 173         struct sk_buff *skb = mhi_res->buf_addr;
 174         int free_desc_count;
 175
 176         free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
 177
 178         if (unlikely(mhi_res->transaction_status)) {
 179                 switch (mhi_res->transaction_status) {
 180                 case -EOVERFLOW:
 181                         /* Packet can not fit in one MHI buffer and has been
 182                          * split over multiple MHI transfers, do re-aggregation.
 183                          * That usually means the device side MTU is larger than
 184                          * the host side MTU/MRU. Since this is not optimal,
 185                          * print a warning (once).
 186                          */
 187                         netdev_warn_once(mhi_netdev->ndev,
 188                                          "Fragmented packets received, fix MTU?\n");
 189                         skb_put(skb, mhi_res->bytes_xferd);
 190                         mhi_net_skb_agg(mhi_netdev, skb);
 191                         break;
 192                 case -ENOTCONN:
 193                         /* MHI layer stopping/resetting the DL channel */
 194                         dev_kfree_skb_any(skb);
 195                         return;
 196                 default:
 197                         /* Unknown error, simply drop */
 198                         dev_kfree_skb_any(skb);
 199                         u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
 200                         u64_stats_inc(&mhi_netdev->stats.rx_errors);
 201                         u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
 202                 }
 203         } else {
 204                 skb_put(skb, mhi_res->bytes_xferd);
 205
 206                 if (mhi_netdev->skbagg_head) {
 207                         /* Aggregate the final fragment */
 208                         skb = mhi_net_skb_agg(mhi_netdev, skb);
 209                         mhi_netdev->skbagg_head = NULL;
 210                 }
 211
 212                 switch (skb->data[0] & 0xf0) {
 213                 case 0x40:
 214                         skb->protocol = htons(ETH_P_IP);
 215                         break;
 216                 case 0x60:
 217                         skb->protocol = htons(ETH_P_IPV6);
 218                         break;
 219                 default:
 220                         skb->protocol = htons(ETH_P_MAP);
 221                         break;
 222                 }
 223
 224                 u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
 225                 u64_stats_inc(&mhi_netdev->stats.rx_packets);
 226                 u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
 227                 u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
 228                 __netif_rx(skb);
 229         }
 230
 231         /* Refill if RX buffers queue becomes low */
 232         if (free_desc_count >= mhi_netdev->rx_queue_sz / 2)
 233                 schedule_delayed_work(&mhi_netdev->rx_refill, 0);
 234 }
 235
 236 static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
 237                                 struct mhi_result *mhi_res)
 238 {
 239         struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 240         struct net_device *ndev = mhi_netdev->ndev;
 241         struct mhi_device *mdev = mhi_netdev->mdev;
 242         struct sk_buff *skb = mhi_res->buf_addr;
 243
 244         /* Hardware has consumed the buffer, so free the skb (which is not
 245          * freed by the MHI stack) and perform accounting.
 246          */
 247         dev_consume_skb_any(skb);
 248
 249         u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
 250         if (unlikely(mhi_res->transaction_status)) {
 251                 /* MHI layer stopping/resetting the UL channel */
 252                 if (mhi_res->transaction_status == -ENOTCONN) {
 253                         u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
 254                         return;
 255                 }
 256
 257                 u64_stats_inc(&mhi_netdev->stats.tx_errors);
 258         } else {
 259                 u64_stats_inc(&mhi_netdev->stats.tx_packets);
 260                 u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
 261         }
 262         u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
 263
 264         if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
 265                 netif_wake_queue(ndev);
 266 }
 267
 268 static void mhi_net_rx_refill_work(struct work_struct *work)
 269 {
 270         struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
 271                                                       rx_refill.work);
 272         struct net_device *ndev = mhi_netdev->ndev;
 273         struct mhi_device *mdev = mhi_netdev->mdev;
 274         struct sk_buff *skb;
 275         unsigned int size;
 276         int err;
 277
 278         size = mhi_netdev->mru ? mhi_netdev->mru : READ_ONCE(ndev->mtu);
 279
 280         while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
 281                 skb = netdev_alloc_skb(ndev, size);
 282                 if (unlikely(!skb))
 283                         break;
 284
 285                 err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
 286                 if (unlikely(err)) {
 287                         net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
 288                                             ndev->name, err);
 289                         kfree_skb(skb);
 290                         break;
 291                 }
 292
 293                 /* Do not hog the CPU if rx buffers are consumed faster than
 294                  * queued (unlikely).
 295                  */
 296                 cond_resched();
 297         }
 298
 299         /* If we're still starved of rx buffers, reschedule later */
 300         if (mhi_get_free_desc_count(mdev, DMA_FROM_DEVICE) == mhi_netdev->rx_queue_sz)
 301                 schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
 302 }
 303
 304 static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
 305 {
 306         struct mhi_net_dev *mhi_netdev;
 307         int err;
 308
 309         mhi_netdev = netdev_priv(ndev);
 310
 311         dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
 312         mhi_netdev->ndev = ndev;
 313         mhi_netdev->mdev = mhi_dev;
 314         mhi_netdev->skbagg_head = NULL;
 315         mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;
 316
 317         INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
 318         u64_stats_init(&mhi_netdev->stats.rx_syncp);
 319         u64_stats_init(&mhi_netdev->stats.tx_syncp);
 320
 321         /* Start MHI channels */
 322         err = mhi_prepare_for_transfer(mhi_dev);
 323         if (err)
 324                 return err;
 325
 326         /* Number of transfer descriptors determines size of the queue */
 327         mhi_netdev->rx_queue_sz = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
 328
 329         err = register_netdev(ndev);
 330         if (err)
 331                 return err;
 332
 333         return 0;
 334 }
 335
 336 static void mhi_net_dellink(struct mhi_device *mhi_dev, struct net_device *ndev)
 337 {
 338         struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
 339
 340         unregister_netdev(ndev);
 341
 342         mhi_unprepare_from_transfer(mhi_dev);
 343
 344         kfree_skb(mhi_netdev->skbagg_head);
 345
 346         free_netdev(ndev);
 347
 348         dev_set_drvdata(&mhi_dev->dev, NULL);
 349 }
 350
 351 static int mhi_net_probe(struct mhi_device *mhi_dev,
 352                          const struct mhi_device_id *id)
 353 {
 354         const struct mhi_device_info *info = (struct mhi_device_info *)id->driver_data;
 355         struct net_device *ndev;
 356         int err;
 357
 358         ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
 359                             NET_NAME_PREDICTABLE, mhi_net_setup);
 360         if (!ndev)
 361                 return -ENOMEM;
 362
 363         SET_NETDEV_DEV(ndev, &mhi_dev->dev);
 364
 365         err = mhi_net_newlink(mhi_dev, ndev);
 366         if (err) {
 367                 free_netdev(ndev);
 368                 return err;
 369         }
 370
 371         return 0;
 372 }
 373
 374 static void mhi_net_remove(struct mhi_device *mhi_dev)
 375 {
 376         struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 377
 378         mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
 379 }
 380
 381 static const struct mhi_device_info mhi_hwip0 = {
 382         .netname = "mhi_hwip%d",
 383 };
 384
 385 static const struct mhi_device_info mhi_swip0 = {
 386         .netname = "mhi_swip%d",
 387 };
 388
 389 static const struct mhi_device_id mhi_net_id_table[] = {
 390         /* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
 391         { .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
 392         /* Software data PATH (to modem CPU) */
 393         { .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
 394         {}
 395 };
 396 MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
 397
 398 static struct mhi_driver mhi_net_driver = {
 399         .probe = mhi_net_probe,
 400         .remove = mhi_net_remove,
 401         .dl_xfer_cb = mhi_net_dl_callback,
 402         .ul_xfer_cb = mhi_net_ul_callback,
 403         .id_table = mhi_net_id_table,
 404         .driver = {
 405                 .name = "mhi_net",
 406         },
 407 };
 408
 409 module_mhi_driver(mhi_net_driver);
 410
 411 MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
 412 MODULE_DESCRIPTION("Network over MHI");
 413 MODULE_LICENSE("GPL v2");