drivers/net/caif/caif_virtio.c

   1 /*
   2  * Copyright (C) ST-Ericsson AB 2013
   3  * Authors: Vicram Arv
   4  *          Dmitry Tarnyagin <[email protected]>
   5  *          Sjur Brendeland
   6  * License terms: GNU General Public License (GPL) version 2
   7  */
   8 #include <linux/module.h>
   9 #include <linux/if_arp.h>
  10 #include <linux/virtio.h>
  11 #include <linux/vringh.h>
  12 #include <linux/debugfs.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/genalloc.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/virtio_ids.h>
  19 #include <linux/virtio_caif.h>
  20 #include <linux/virtio_ring.h>
  21 #include <linux/dma-mapping.h>
  22 #include <net/caif/caif_dev.h>
  23 #include <linux/virtio_config.h>
  24
  25 MODULE_LICENSE("GPL v2");
  26 MODULE_AUTHOR("Vicram Arv");
  27 MODULE_AUTHOR("Sjur Brendeland");
  28 MODULE_DESCRIPTION("Virtio CAIF Driver");
  29
  30 /* NAPI schedule quota */
  31 #define CFV_DEFAULT_QUOTA 32
  32
  33 /* Defaults used if virtio config space is unavailable */
  34 #define CFV_DEF_MTU_SIZE 4096
  35 #define CFV_DEF_HEADROOM 32
  36 #define CFV_DEF_TAILROOM 32
  37
  38 /* Required IP header alignment */
  39 #define IP_HDR_ALIGN 4
  40
  41 /* struct cfv_napi_contxt - NAPI context info
  42  * @riov: IOV holding data read from the ring. Note that riov may
  43  *        still hold data when cfv_rx_poll() returns.
  44  * @head: Last descriptor ID we received from vringh_getdesc_kern.
  45  *        We use this to put descriptor back on the used ring. USHRT_MAX is
  46  *        used to indicate invalid head-id.
  47  */
  48 struct cfv_napi_context {
  49         struct vringh_kiov riov;
  50         unsigned short head;
  51 };
  52
  53 /* struct cfv_stats - statistics for debugfs
  54  * @rx_napi_complete:   Number of NAPI completions (RX)
  55  * @rx_napi_resched:    Number of calls where the full quota was used (RX)
  56  * @rx_nomem:           Number of SKB alloc failures (RX)
  57  * @rx_kicks:           Number of RX kicks
  58  * @tx_full_ring:       Number times TX ring was full
  59  * @tx_no_mem:          Number of times TX went out of memory
  60  * @tx_flow_on:         Number of flow on (TX)
  61  * @tx_kicks:           Number of TX kicks
  62  */
  63 struct cfv_stats {
  64         u32 rx_napi_complete;
  65         u32 rx_napi_resched;
  66         u32 rx_nomem;
  67         u32 rx_kicks;
  68         u32 tx_full_ring;
  69         u32 tx_no_mem;
  70         u32 tx_flow_on;
  71         u32 tx_kicks;
  72 };
  73
  74 /* struct cfv_info - Caif Virtio control structure
  75  * @cfdev:      caif common header
  76  * @vdev:       Associated virtio device
  77  * @vr_rx:      rx/downlink host vring
  78  * @vq_tx:      tx/uplink virtqueue
  79  * @ndev:       CAIF link layer device
  80  * @watermark_tx: indicates number of free descriptors we need
  81  *              to reopen the tx-queues after overload.
  82  * @tx_lock:    protects vq_tx from concurrent use
  83  * @tx_release_tasklet: Tasklet for freeing consumed TX buffers
  84  * @napi:       Napi context used in cfv_rx_poll()
  85  * @ctx:        Context data used in cfv_rx_poll()
  86  * @tx_hr:      transmit headroom
  87  * @rx_hr:      receive headroom
  88  * @tx_tr:      transmit tail room
  89  * @rx_tr:      receive tail room
  90  * @mtu:        transmit max size
  91  * @mru:        receive max size
  92  * @allocsz:    size of dma memory reserved for TX buffers
  93  * @alloc_addr: virtual address to dma memory for TX buffers
  94  * @alloc_dma:  dma address to dma memory for TX buffers
  95  * @genpool:    Gen Pool used for allocating TX buffers
  96  * @reserved_mem: Pointer to memory reserve allocated from genpool
  97  * @reserved_size: Size of memory reserve allocated from genpool
  98  * @stats:       Statistics exposed in sysfs
  99  * @debugfs:    Debugfs dentry for statistic counters
 100  */
 101 struct cfv_info {
 102         struct caif_dev_common cfdev;
 103         struct virtio_device *vdev;
 104         struct vringh *vr_rx;
 105         struct virtqueue *vq_tx;
 106         struct net_device *ndev;
 107         unsigned int watermark_tx;
 108         /* Protect access to vq_tx */
 109         spinlock_t tx_lock;
 110         struct tasklet_struct tx_release_tasklet;
 111         struct napi_struct napi;
 112         struct cfv_napi_context ctx;
 113         u16 tx_hr;
 114         u16 rx_hr;
 115         u16 tx_tr;
 116         u16 rx_tr;
 117         u32 mtu;
 118         u32 mru;
 119         size_t allocsz;
 120         void *alloc_addr;
 121         dma_addr_t alloc_dma;
 122         struct gen_pool *genpool;
 123         unsigned long reserved_mem;
 124         size_t reserved_size;
 125         struct cfv_stats stats;
 126         struct dentry *debugfs;
 127 };
 128
 129 /* struct buf_info - maintains transmit buffer data handle
 130  * @size:       size of transmit buffer
 131  * @dma_handle: handle to allocated dma device memory area
 132  * @vaddr:      virtual address mapping to allocated memory area
 133  */
 134 struct buf_info {
 135         size_t size;
 136         u8 *vaddr;
 137 };
 138
 139 /* Called from virtio device, in IRQ context */
 140 static void cfv_release_cb(struct virtqueue *vq_tx)
 141 {
 142         struct cfv_info *cfv = vq_tx->vdev->priv;
 143
 144         ++cfv->stats.tx_kicks;
 145         tasklet_schedule(&cfv->tx_release_tasklet);
 146 }
 147
 148 static void free_buf_info(struct cfv_info *cfv, struct buf_info *buf_info)
 149 {
 150         if (!buf_info)
 151                 return;
 152         gen_pool_free(cfv->genpool, (unsigned long) buf_info->vaddr,
 153                       buf_info->size);
 154         kfree(buf_info);
 155 }
 156
 157 /* This is invoked whenever the remote processor completed processing
 158  * a TX msg we just sent, and the buffer is put back to the used ring.
 159  */
 160 static void cfv_release_used_buf(struct virtqueue *vq_tx)
 161 {
 162         struct cfv_info *cfv = vq_tx->vdev->priv;
 163         unsigned long flags;
 164
 165         BUG_ON(vq_tx != cfv->vq_tx);
 166
 167         for (;;) {
 168                 unsigned int len;
 169                 struct buf_info *buf_info;
 170
 171                 /* Get used buffer from used ring to recycle used descriptors */
 172                 spin_lock_irqsave(&cfv->tx_lock, flags);
 173                 buf_info = virtqueue_get_buf(vq_tx, &len);
 174                 spin_unlock_irqrestore(&cfv->tx_lock, flags);
 175
 176                 /* Stop looping if there are no more buffers to free */
 177                 if (!buf_info)
 178                         break;
 179
 180                 free_buf_info(cfv, buf_info);
 181
 182                 /* watermark_tx indicates if we previously stopped the tx
 183                  * queues. If we have enough free stots in the virtio ring,
 184                  * re-establish memory reserved and open up tx queues.
 185                  */
 186                 if (cfv->vq_tx->num_free <= cfv->watermark_tx)
 187                         continue;
 188
 189                 /* Re-establish memory reserve */
 190                 if (cfv->reserved_mem == 0 && cfv->genpool)
 191                         cfv->reserved_mem =
 192                                 gen_pool_alloc(cfv->genpool,
 193                                                cfv->reserved_size);
 194
 195                 /* Open up the tx queues */
 196                 if (cfv->reserved_mem) {
 197                         cfv->watermark_tx =
 198                                 virtqueue_get_vring_size(cfv->vq_tx);
 199                         netif_tx_wake_all_queues(cfv->ndev);
 200                         /* Buffers are recycled in cfv_netdev_tx, so
 201                          * disable notifications when queues are opened.
 202                          */
 203                         virtqueue_disable_cb(cfv->vq_tx);
 204                         ++cfv->stats.tx_flow_on;
 205                 } else {
 206                         /* if no memory reserve, wait for more free slots */
 207                         WARN_ON(cfv->watermark_tx >
 208                                virtqueue_get_vring_size(cfv->vq_tx));
 209                         cfv->watermark_tx +=
 210                                 virtqueue_get_vring_size(cfv->vq_tx) / 4;
 211                 }
 212         }
 213 }
 214
 215 /* Allocate a SKB and copy packet data to it */
 216 static struct sk_buff *cfv_alloc_and_copy_skb(int *err,
 217                                               struct cfv_info *cfv,
 218                                               u8 *frm, u32 frm_len)
 219 {
 220         struct sk_buff *skb;
 221         u32 cfpkt_len, pad_len;
 222
 223         *err = 0;
 224         /* Verify that packet size with down-link header and mtu size */
 225         if (frm_len > cfv->mru || frm_len <= cfv->rx_hr + cfv->rx_tr) {
 226                 netdev_err(cfv->ndev,
 227                            "Invalid frmlen:%u  mtu:%u hr:%d tr:%d\n",
 228                            frm_len, cfv->mru,  cfv->rx_hr,
 229                            cfv->rx_tr);
 230                 *err = -EPROTO;
 231                 return NULL;
 232         }
 233
 234         cfpkt_len = frm_len - (cfv->rx_hr + cfv->rx_tr);
 235         pad_len = (unsigned long)(frm + cfv->rx_hr) & (IP_HDR_ALIGN - 1);
 236
 237         skb = netdev_alloc_skb(cfv->ndev, frm_len + pad_len);
 238         if (!skb) {
 239                 *err = -ENOMEM;
 240                 return NULL;
 241         }
 242
 243         skb_reserve(skb, cfv->rx_hr + pad_len);
 244
 245         memcpy(skb_put(skb, cfpkt_len), frm + cfv->rx_hr, cfpkt_len);
 246         return skb;
 247 }
 248
 249 /* Get packets from the host vring */
 250 static int cfv_rx_poll(struct napi_struct *napi, int quota)
 251 {
 252         struct cfv_info *cfv = container_of(napi, struct cfv_info, napi);
 253         int rxcnt = 0;
 254         int err = 0;
 255         void *buf;
 256         struct sk_buff *skb;
 257         struct vringh_kiov *riov = &cfv->ctx.riov;
 258         unsigned int skb_len;
 259
 260         do {
 261                 skb = NULL;
 262
 263                 /* Put the previous iovec back on the used ring and
 264                  * fetch a new iovec if we have processed all elements.
 265                  */
 266                 if (riov->i == riov->used) {
 267                         if (cfv->ctx.head != USHRT_MAX) {
 268                                 vringh_complete_kern(cfv->vr_rx,
 269                                                      cfv->ctx.head,
 270                                                      0);
 271                                 cfv->ctx.head = USHRT_MAX;
 272                         }
 273
 274                         err = vringh_getdesc_kern(
 275                                 cfv->vr_rx,
 276                                 riov,
 277                                 NULL,
 278                                 &cfv->ctx.head,
 279                                 GFP_ATOMIC);
 280
 281                         if (err <= 0)
 282                                 goto exit;
 283                 }
 284
 285                 buf = phys_to_virt((unsigned long) riov->iov[riov->i].iov_base);
 286                 /* TODO: Add check on valid buffer address */
 287
 288                 skb = cfv_alloc_and_copy_skb(&err, cfv, buf,
 289                                              riov->iov[riov->i].iov_len);
 290                 if (unlikely(err))
 291                         goto exit;
 292
 293                 /* Push received packet up the stack. */
 294                 skb_len = skb->len;
 295                 skb->protocol = htons(ETH_P_CAIF);
 296                 skb_reset_mac_header(skb);
 297                 skb->dev = cfv->ndev;
 298                 err = netif_receive_skb(skb);
 299                 if (unlikely(err)) {
 300                         ++cfv->ndev->stats.rx_dropped;
 301                 } else {
 302                         ++cfv->ndev->stats.rx_packets;
 303                         cfv->ndev->stats.rx_bytes += skb_len;
 304                 }
 305
 306                 ++riov->i;
 307                 ++rxcnt;
 308         } while (rxcnt < quota);
 309
 310         ++cfv->stats.rx_napi_resched;
 311         goto out;
 312
 313 exit:
 314         switch (err) {
 315         case 0:
 316                 ++cfv->stats.rx_napi_complete;
 317
 318                 /* Really out of patckets? (stolen from virtio_net)*/
 319                 napi_complete(napi);
 320                 if (unlikely(!vringh_notify_enable_kern(cfv->vr_rx)) &&
 321                     napi_schedule_prep(napi)) {
 322                         vringh_notify_disable_kern(cfv->vr_rx);
 323                         __napi_schedule(napi);
 324                 }
 325                 break;
 326
 327         case -ENOMEM:
 328                 ++cfv->stats.rx_nomem;
 329                 dev_kfree_skb(skb);
 330                 /* Stop NAPI poll on OOM, we hope to be polled later */
 331                 napi_complete(napi);
 332                 vringh_notify_enable_kern(cfv->vr_rx);
 333                 break;
 334
 335         default:
 336                 /* We're doomed, any modem fault is fatal */
 337                 netdev_warn(cfv->ndev, "Bad ring, disable device\n");
 338                 cfv->ndev->stats.rx_dropped = riov->used - riov->i;
 339                 napi_complete(napi);
 340                 vringh_notify_disable_kern(cfv->vr_rx);
 341                 netif_carrier_off(cfv->ndev);
 342                 break;
 343         }
 344 out:
 345         if (rxcnt && vringh_need_notify_kern(cfv->vr_rx) > 0)
 346                 vringh_notify(cfv->vr_rx);
 347         return rxcnt;
 348 }
 349
 350 static void cfv_recv(struct virtio_device *vdev, struct vringh *vr_rx)
 351 {
 352         struct cfv_info *cfv = vdev->priv;
 353
 354         ++cfv->stats.rx_kicks;
 355         vringh_notify_disable_kern(cfv->vr_rx);
 356         napi_schedule(&cfv->napi);
 357 }
 358
 359 static void cfv_destroy_genpool(struct cfv_info *cfv)
 360 {
 361         if (cfv->alloc_addr)
 362                 dma_free_coherent(cfv->vdev->dev.parent->parent,
 363                                   cfv->allocsz, cfv->alloc_addr,
 364                                   cfv->alloc_dma);
 365
 366         if (!cfv->genpool)
 367                 return;
 368         gen_pool_free(cfv->genpool,  cfv->reserved_mem,
 369                       cfv->reserved_size);
 370         gen_pool_destroy(cfv->genpool);
 371         cfv->genpool = NULL;
 372 }
 373
 374 static int cfv_create_genpool(struct cfv_info *cfv)
 375 {
 376         int err;
 377
 378         /* dma_alloc can only allocate whole pages, and we need a more
 379          * fine graned allocation so we use genpool. We ask for space needed
 380          * by IP and a full ring. If the dma allcoation fails we retry with a
 381          * smaller allocation size.
 382          */
 383         err = -ENOMEM;
 384         cfv->allocsz = (virtqueue_get_vring_size(cfv->vq_tx) *
 385                         (ETH_DATA_LEN + cfv->tx_hr + cfv->tx_tr) * 11)/10;
 386         if (cfv->allocsz <= (num_possible_cpus() + 1) * cfv->ndev->mtu)
 387                 return -EINVAL;
 388
 389         for (;;) {
 390                 if (cfv->allocsz <= num_possible_cpus() * cfv->ndev->mtu) {
 391                         netdev_info(cfv->ndev, "Not enough device memory\n");
 392                         return -ENOMEM;
 393                 }
 394
 395                 cfv->alloc_addr = dma_alloc_coherent(
 396                                                 cfv->vdev->dev.parent->parent,
 397                                                 cfv->allocsz, &cfv->alloc_dma,
 398                                                 GFP_ATOMIC);
 399                 if (cfv->alloc_addr)
 400                         break;
 401
 402                 cfv->allocsz = (cfv->allocsz * 3) >> 2;
 403         }
 404
 405         netdev_dbg(cfv->ndev, "Allocated %zd bytes from dma-memory\n",
 406                    cfv->allocsz);
 407
 408         /* Allocate on 128 bytes boundaries (1 << 7)*/
 409         cfv->genpool = gen_pool_create(7, -1);
 410         if (!cfv->genpool)
 411                 goto err;
 412
 413         err = gen_pool_add_virt(cfv->genpool, (unsigned long)cfv->alloc_addr,
 414                                 (phys_addr_t)virt_to_phys(cfv->alloc_addr),
 415                                 cfv->allocsz, -1);
 416         if (err)
 417                 goto err;
 418
 419         /* Reserve some memory for low memory situations. If we hit the roof
 420          * in the memory pool, we stop TX flow and release the reserve.
 421          */
 422         cfv->reserved_size = num_possible_cpus() * cfv->ndev->mtu;
 423         cfv->reserved_mem = gen_pool_alloc(cfv->genpool,
 424                                            cfv->reserved_size);
 425         if (!cfv->reserved_mem) {
 426                 err = -ENOMEM;
 427                 goto err;
 428         }
 429
 430         cfv->watermark_tx = virtqueue_get_vring_size(cfv->vq_tx);
 431         return 0;
 432 err:
 433         cfv_destroy_genpool(cfv);
 434         return err;
 435 }
 436
 437 /* Enable the CAIF interface and allocate the memory-pool */
 438 static int cfv_netdev_open(struct net_device *netdev)
 439 {
 440         struct cfv_info *cfv = netdev_priv(netdev);
 441
 442         if (cfv_create_genpool(cfv))
 443                 return -ENOMEM;
 444
 445         netif_carrier_on(netdev);
 446         napi_enable(&cfv->napi);
 447
 448         /* Schedule NAPI to read any pending packets */
 449         napi_schedule(&cfv->napi);
 450         return 0;
 451 }
 452
 453 /* Disable the CAIF interface and free the memory-pool */
 454 static int cfv_netdev_close(struct net_device *netdev)
 455 {
 456         struct cfv_info *cfv = netdev_priv(netdev);
 457         unsigned long flags;
 458         struct buf_info *buf_info;
 459
 460         /* Disable interrupts, queues and NAPI polling */
 461         netif_carrier_off(netdev);
 462         virtqueue_disable_cb(cfv->vq_tx);
 463         vringh_notify_disable_kern(cfv->vr_rx);
 464         napi_disable(&cfv->napi);
 465
 466         /* Release any TX buffers on both used and avilable rings */
 467         cfv_release_used_buf(cfv->vq_tx);
 468         spin_lock_irqsave(&cfv->tx_lock, flags);
 469         while ((buf_info = virtqueue_detach_unused_buf(cfv->vq_tx)))
 470                 free_buf_info(cfv, buf_info);
 471         spin_unlock_irqrestore(&cfv->tx_lock, flags);
 472
 473         /* Release all dma allocated memory and destroy the pool */
 474         cfv_destroy_genpool(cfv);
 475         return 0;
 476 }
 477
 478 /* Allocate a buffer in dma-memory and copy skb to it */
 479 static struct buf_info *cfv_alloc_and_copy_to_shm(struct cfv_info *cfv,
 480                                                        struct sk_buff *skb,
 481                                                        struct scatterlist *sg)
 482 {
 483         struct caif_payload_info *info = (void *)&skb->cb;
 484         struct buf_info *buf_info = NULL;
 485         u8 pad_len, hdr_ofs;
 486
 487         if (!cfv->genpool)
 488                 goto err;
 489
 490         if (unlikely(cfv->tx_hr + skb->len + cfv->tx_tr > cfv->mtu)) {
 491                 netdev_warn(cfv->ndev, "Invalid packet len (%d > %d)\n",
 492                             cfv->tx_hr + skb->len + cfv->tx_tr, cfv->mtu);
 493                 goto err;
 494         }
 495
 496         buf_info = kmalloc(sizeof(struct buf_info), GFP_ATOMIC);
 497         if (unlikely(!buf_info))
 498                 goto err;
 499
 500         /* Make the IP header aligned in tbe buffer */
 501         hdr_ofs = cfv->tx_hr + info->hdr_len;
 502         pad_len = hdr_ofs & (IP_HDR_ALIGN - 1);
 503         buf_info->size = cfv->tx_hr + skb->len + cfv->tx_tr + pad_len;
 504
 505         /* allocate dma memory buffer */
 506         buf_info->vaddr = (void *)gen_pool_alloc(cfv->genpool, buf_info->size);
 507         if (unlikely(!buf_info->vaddr))
 508                 goto err;
 509
 510         /* copy skbuf contents to send buffer */
 511         skb_copy_bits(skb, 0, buf_info->vaddr + cfv->tx_hr + pad_len, skb->len);
 512         sg_init_one(sg, buf_info->vaddr + pad_len,
 513                     skb->len + cfv->tx_hr + cfv->rx_hr);
 514
 515         return buf_info;
 516 err:
 517         kfree(buf_info);
 518         return NULL;
 519 }
 520
 521 /* Put the CAIF packet on the virtio ring and kick the receiver */
 522 static int cfv_netdev_tx(struct sk_buff *skb, struct net_device *netdev)
 523 {
 524         struct cfv_info *cfv = netdev_priv(netdev);
 525         struct buf_info *buf_info;
 526         struct scatterlist sg;
 527         unsigned long flags;
 528         bool flow_off = false;
 529         int ret;
 530
 531         /* garbage collect released buffers */
 532         cfv_release_used_buf(cfv->vq_tx);
 533         spin_lock_irqsave(&cfv->tx_lock, flags);
 534
 535         /* Flow-off check takes into account number of cpus to make sure
 536          * virtqueue will not be overfilled in any possible smp conditions.
 537          *
 538          * Flow-on is triggered when sufficient buffers are freed
 539          */
 540         if (unlikely(cfv->vq_tx->num_free <= num_present_cpus())) {
 541                 flow_off = true;
 542                 cfv->stats.tx_full_ring++;
 543         }
 544
 545         /* If we run out of memory, we release the memory reserve and retry
 546          * allocation.
 547          */
 548         buf_info = cfv_alloc_and_copy_to_shm(cfv, skb, &sg);
 549         if (unlikely(!buf_info)) {
 550                 cfv->stats.tx_no_mem++;
 551                 flow_off = true;
 552
 553                 if (cfv->reserved_mem && cfv->genpool) {
 554                         gen_pool_free(cfv->genpool,  cfv->reserved_mem,
 555                                       cfv->reserved_size);
 556                         cfv->reserved_mem = 0;
 557                         buf_info = cfv_alloc_and_copy_to_shm(cfv, skb, &sg);
 558                 }
 559         }
 560
 561         if (unlikely(flow_off)) {
 562                 /* Turn flow on when a 1/4 of the descriptors are released */
 563                 cfv->watermark_tx = virtqueue_get_vring_size(cfv->vq_tx) / 4;
 564                 /* Enable notifications of recycled TX buffers */
 565                 virtqueue_enable_cb(cfv->vq_tx);
 566                 netif_tx_stop_all_queues(netdev);
 567         }
 568
 569         if (unlikely(!buf_info)) {
 570                 /* If the memory reserve does it's job, this shouldn't happen */
 571                 netdev_warn(cfv->ndev, "Out of gen_pool memory\n");
 572                 goto err;
 573         }
 574
 575         ret = virtqueue_add_outbuf(cfv->vq_tx, &sg, 1, buf_info, GFP_ATOMIC);
 576         if (unlikely((ret < 0))) {
 577                 /* If flow control works, this shouldn't happen */
 578                 netdev_warn(cfv->ndev, "Failed adding buffer to TX vring:%d\n",
 579                             ret);
 580                 goto err;
 581         }
 582
 583         /* update netdev statistics */
 584         cfv->ndev->stats.tx_packets++;
 585         cfv->ndev->stats.tx_bytes += skb->len;
 586         spin_unlock_irqrestore(&cfv->tx_lock, flags);
 587
 588         /* tell the remote processor it has a pending message to read */
 589         virtqueue_kick(cfv->vq_tx);
 590
 591         dev_kfree_skb(skb);
 592         return NETDEV_TX_OK;
 593 err:
 594         spin_unlock_irqrestore(&cfv->tx_lock, flags);
 595         cfv->ndev->stats.tx_dropped++;
 596         free_buf_info(cfv, buf_info);
 597         dev_kfree_skb(skb);
 598         return NETDEV_TX_OK;
 599 }
 600
 601 static void cfv_tx_release_tasklet(unsigned long drv)
 602 {
 603         struct cfv_info *cfv = (struct cfv_info *)drv;
 604         cfv_release_used_buf(cfv->vq_tx);
 605 }
 606
 607 static const struct net_device_ops cfv_netdev_ops = {
 608         .ndo_open = cfv_netdev_open,
 609         .ndo_stop = cfv_netdev_close,
 610         .ndo_start_xmit = cfv_netdev_tx,
 611 };
 612
 613 static void cfv_netdev_setup(struct net_device *netdev)
 614 {
 615         netdev->netdev_ops = &cfv_netdev_ops;
 616         netdev->type = ARPHRD_CAIF;
 617         netdev->tx_queue_len = 100;
 618         netdev->flags = IFF_POINTOPOINT | IFF_NOARP;
 619         netdev->mtu = CFV_DEF_MTU_SIZE;
 620         netdev->destructor = free_netdev;
 621 }
 622
 623 /* Create debugfs counters for the device */
 624 static inline void debugfs_init(struct cfv_info *cfv)
 625 {
 626         cfv->debugfs =
 627                 debugfs_create_dir(netdev_name(cfv->ndev), NULL);
 628
 629         if (IS_ERR(cfv->debugfs))
 630                 return;
 631
 632         debugfs_create_u32("rx-napi-complete", S_IRUSR, cfv->debugfs,
 633                            &cfv->stats.rx_napi_complete);
 634         debugfs_create_u32("rx-napi-resched", S_IRUSR, cfv->debugfs,
 635                            &cfv->stats.rx_napi_resched);
 636         debugfs_create_u32("rx-nomem", S_IRUSR, cfv->debugfs,
 637                            &cfv->stats.rx_nomem);
 638         debugfs_create_u32("rx-kicks", S_IRUSR, cfv->debugfs,
 639                            &cfv->stats.rx_kicks);
 640         debugfs_create_u32("tx-full-ring", S_IRUSR, cfv->debugfs,
 641                            &cfv->stats.tx_full_ring);
 642         debugfs_create_u32("tx-no-mem", S_IRUSR, cfv->debugfs,
 643                            &cfv->stats.tx_no_mem);
 644         debugfs_create_u32("tx-kicks", S_IRUSR, cfv->debugfs,
 645                            &cfv->stats.tx_kicks);
 646         debugfs_create_u32("tx-flow-on", S_IRUSR, cfv->debugfs,
 647                            &cfv->stats.tx_flow_on);
 648 }
 649
 650 /* Setup CAIF for the a virtio device */
 651 static int cfv_probe(struct virtio_device *vdev)
 652 {
 653         vq_callback_t *vq_cbs = cfv_release_cb;
 654         vrh_callback_t *vrh_cbs = cfv_recv;
 655         const char *names =  "output";
 656         const char *cfv_netdev_name = "cfvrt";
 657         struct net_device *netdev;
 658         struct cfv_info *cfv;
 659         int err = -EINVAL;
 660
 661         netdev = alloc_netdev(sizeof(struct cfv_info), cfv_netdev_name,
 662                               NET_NAME_UNKNOWN, cfv_netdev_setup);
 663         if (!netdev)
 664                 return -ENOMEM;
 665
 666         cfv = netdev_priv(netdev);
 667         cfv->vdev = vdev;
 668         cfv->ndev = netdev;
 669
 670         spin_lock_init(&cfv->tx_lock);
 671
 672         /* Get the RX virtio ring. This is a "host side vring". */
 673         err = -ENODEV;
 674         if (!vdev->vringh_config || !vdev->vringh_config->find_vrhs)
 675                 goto err;
 676
 677         err = vdev->vringh_config->find_vrhs(vdev, 1, &cfv->vr_rx, &vrh_cbs);
 678         if (err)
 679                 goto err;
 680
 681         /* Get the TX virtio ring. This is a "guest side vring". */
 682         err = vdev->config->find_vqs(vdev, 1, &cfv->vq_tx, &vq_cbs, &names);
 683         if (err)
 684                 goto err;
 685
 686         /* Get the CAIF configuration from virtio config space, if available */
 687         if (vdev->config->get) {
 688                 virtio_cread(vdev, struct virtio_caif_transf_config, headroom,
 689                              &cfv->tx_hr);
 690                 virtio_cread(vdev, struct virtio_caif_transf_config, headroom,
 691                              &cfv->rx_hr);
 692                 virtio_cread(vdev, struct virtio_caif_transf_config, tailroom,
 693                              &cfv->tx_tr);
 694                 virtio_cread(vdev, struct virtio_caif_transf_config, tailroom,
 695                              &cfv->rx_tr);
 696                 virtio_cread(vdev, struct virtio_caif_transf_config, mtu,
 697                              &cfv->mtu);
 698                 virtio_cread(vdev, struct virtio_caif_transf_config, mtu,
 699                              &cfv->mru);
 700         } else {
 701                 cfv->tx_hr = CFV_DEF_HEADROOM;
 702                 cfv->rx_hr = CFV_DEF_HEADROOM;
 703                 cfv->tx_tr = CFV_DEF_TAILROOM;
 704                 cfv->rx_tr = CFV_DEF_TAILROOM;
 705                 cfv->mtu = CFV_DEF_MTU_SIZE;
 706                 cfv->mru = CFV_DEF_MTU_SIZE;
 707         }
 708
 709         netdev->needed_headroom = cfv->tx_hr;
 710         netdev->needed_tailroom = cfv->tx_tr;
 711
 712         /* Disable buffer release interrupts unless we have stopped TX queues */
 713         virtqueue_disable_cb(cfv->vq_tx);
 714
 715         netdev->mtu = cfv->mtu - cfv->tx_tr;
 716         vdev->priv = cfv;
 717
 718         /* Initialize NAPI poll context data */
 719         vringh_kiov_init(&cfv->ctx.riov, NULL, 0);
 720         cfv->ctx.head = USHRT_MAX;
 721         netif_napi_add(netdev, &cfv->napi, cfv_rx_poll, CFV_DEFAULT_QUOTA);
 722
 723         tasklet_init(&cfv->tx_release_tasklet,
 724                      cfv_tx_release_tasklet,
 725                      (unsigned long)cfv);
 726
 727         /* Carrier is off until netdevice is opened */
 728         netif_carrier_off(netdev);
 729
 730         /* register Netdev */
 731         err = register_netdev(netdev);
 732         if (err) {
 733                 dev_err(&vdev->dev, "Unable to register netdev (%d)\n", err);
 734                 goto err;
 735         }
 736
 737         debugfs_init(cfv);
 738
 739         return 0;
 740 err:
 741         netdev_warn(cfv->ndev, "CAIF Virtio probe failed:%d\n", err);
 742
 743         if (cfv->vr_rx)
 744                 vdev->vringh_config->del_vrhs(cfv->vdev);
 745         if (cfv->vdev)
 746                 vdev->config->del_vqs(cfv->vdev);
 747         free_netdev(netdev);
 748         return err;
 749 }
 750
 751 static void cfv_remove(struct virtio_device *vdev)
 752 {
 753         struct cfv_info *cfv = vdev->priv;
 754
 755         rtnl_lock();
 756         dev_close(cfv->ndev);
 757         rtnl_unlock();
 758
 759         tasklet_kill(&cfv->tx_release_tasklet);
 760         debugfs_remove_recursive(cfv->debugfs);
 761
 762         vringh_kiov_cleanup(&cfv->ctx.riov);
 763         vdev->config->reset(vdev);
 764         vdev->vringh_config->del_vrhs(cfv->vdev);
 765         cfv->vr_rx = NULL;
 766         vdev->config->del_vqs(cfv->vdev);
 767         unregister_netdev(cfv->ndev);
 768 }
 769
 770 static struct virtio_device_id id_table[] = {
 771         { VIRTIO_ID_CAIF, VIRTIO_DEV_ANY_ID },
 772         { 0 },
 773 };
 774
 775 static unsigned int features[] = {
 776 };
 777
 778 static struct virtio_driver caif_virtio_driver = {
 779         .feature_table          = features,
 780         .feature_table_size     = ARRAY_SIZE(features),
 781         .driver.name            = KBUILD_MODNAME,
 782         .driver.owner           = THIS_MODULE,
 783         .id_table               = id_table,
 784         .probe                  = cfv_probe,
 785         .remove                 = cfv_remove,
 786 };
 787
 788 module_virtio_driver(caif_virtio_driver);
 789 MODULE_DEVICE_TABLE(virtio, id_table);