drivers/net/can/rx-offload.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2014      Protonic Holland,
   3  *                         David Jander
   4  * Copyright (C) 2014-2017 Pengutronix,
   5  *                         Marc Kleine-Budde <kernel@pengutronix.de>
   6  */
   7
   8 #include <linux/can/dev.h>
   9 #include <linux/can/rx-offload.h>
  10
  11 struct can_rx_offload_cb {
  12         u32 timestamp;
  13 };
  14
  15 static inline struct can_rx_offload_cb *
  16 can_rx_offload_get_cb(struct sk_buff *skb)
  17 {
  18         BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));
  19
  20         return (struct can_rx_offload_cb *)skb->cb;
  21 }
  22
  23 static inline bool
  24 can_rx_offload_le(struct can_rx_offload *offload,
  25                   unsigned int a, unsigned int b)
  26 {
  27         if (offload->inc)
  28                 return a <= b;
  29         else
  30                 return a >= b;
  31 }
  32
  33 static inline unsigned int
  34 can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
  35 {
  36         if (offload->inc)
  37                 return (*val)++;
  38         else
  39                 return (*val)--;
  40 }
  41
  42 static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
  43 {
  44         struct can_rx_offload *offload = container_of(napi,
  45                                                       struct can_rx_offload,
  46                                                       napi);
  47         struct net_device *dev = offload->dev;
  48         struct net_device_stats *stats = &dev->stats;
  49         struct sk_buff *skb;
  50         int work_done = 0;
  51
  52         while ((work_done < quota) &&
  53                (skb = skb_dequeue(&offload->skb_queue))) {
  54                 struct can_frame *cf = (struct can_frame *)skb->data;
  55
  56                 work_done++;
  57                 stats->rx_packets++;
  58                 stats->rx_bytes += cf->can_dlc;
  59                 netif_receive_skb(skb);
  60         }
  61
  62         if (work_done < quota) {
  63                 napi_complete_done(napi, work_done);
  64
  65                 /* Check if there was another interrupt */
  66                 if (!skb_queue_empty(&offload->skb_queue))
  67                         napi_reschedule(&offload->napi);
  68         }
  69
  70         can_led_event(offload->dev, CAN_LED_EVENT_RX);
  71
  72         return work_done;
  73 }
  74
  75 static inline void
  76 __skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
  77                      int (*compare)(struct sk_buff *a, struct sk_buff *b))
  78 {
  79         struct sk_buff *pos, *insert = NULL;
  80
  81         skb_queue_reverse_walk(head, pos) {
  82                 const struct can_rx_offload_cb *cb_pos, *cb_new;
  83
  84                 cb_pos = can_rx_offload_get_cb(pos);
  85                 cb_new = can_rx_offload_get_cb(new);
  86
  87                 netdev_dbg(new->dev,
  88                            "%s: pos=0x%08x, new=0x%08x, diff=%10d, queue_len=%d\n",
  89                            __func__,
  90                            cb_pos->timestamp, cb_new->timestamp,
  91                            cb_new->timestamp - cb_pos->timestamp,
  92                            skb_queue_len(head));
  93
  94                 if (compare(pos, new) < 0)
  95                         continue;
  96                 insert = pos;
  97                 break;
  98         }
  99         if (!insert)
 100                 __skb_queue_head(head, new);
 101         else
 102                 __skb_queue_after(head, insert, new);
 103 }
 104
 105 static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
 106 {
 107         const struct can_rx_offload_cb *cb_a, *cb_b;
 108
 109         cb_a = can_rx_offload_get_cb(a);
 110         cb_b = can_rx_offload_get_cb(b);
 111
 112         /* Subtract two u32 and return result as int, to keep
 113          * difference steady around the u32 overflow.
 114          */
 115         return cb_b->timestamp - cb_a->timestamp;
 116 }
 117
 118 /**
 119  * can_rx_offload_offload_one() - Read one CAN frame from HW
 120  * @offload: pointer to rx_offload context
 121  * @n: number of mailbox to read
 122  *
 123  * The task of this function is to read a CAN frame from mailbox @n
 124  * from the device and return the mailbox's content as a struct
 125  * sk_buff.
 126  *
 127  * If the struct can_rx_offload::skb_queue exceeds the maximal queue
 128  * length (struct can_rx_offload::skb_queue_len_max) or no skb can be
 129  * allocated, the mailbox contents is discarded by reading it into an
 130  * overflow buffer. This way the mailbox is marked as free by the
 131  * driver.
 132  *
 133  * Return: A pointer to skb containing the CAN frame on success.
 134  *
 135  *         NULL if the mailbox @n is empty.
 136  *
 137  *         ERR_PTR() in case of an error
 138  */
 139 static struct sk_buff *
 140 can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
 141 {
 142         struct sk_buff *skb = NULL, *skb_error = NULL;
 143         struct can_rx_offload_cb *cb;
 144         struct can_frame *cf;
 145         int ret;
 146
 147         if (likely(skb_queue_len(&offload->skb_queue) <
 148                    offload->skb_queue_len_max)) {
 149                 skb = alloc_can_skb(offload->dev, &cf);
 150                 if (unlikely(!skb))
 151                         skb_error = ERR_PTR(-ENOMEM);   /* skb alloc failed */
 152         } else {
 153                 skb_error = ERR_PTR(-ENOBUFS);          /* skb_queue is full */
 154         }
 155
 156         /* If queue is full or skb not available, drop by reading into
 157          * overflow buffer.
 158          */
 159         if (unlikely(skb_error)) {
 160                 struct can_frame cf_overflow;
 161                 u32 timestamp;
 162
 163                 ret = offload->mailbox_read(offload, &cf_overflow,
 164                                             &timestamp, n);
 165
 166                 /* Mailbox was empty. */
 167                 if (unlikely(!ret))
 168                         return NULL;
 169
 170                 /* Mailbox has been read and we're dropping it or
 171                  * there was a problem reading the mailbox.
 172                  *
 173                  * Increment error counters in any case.
 174                  */
 175                 offload->dev->stats.rx_dropped++;
 176                 offload->dev->stats.rx_fifo_errors++;
 177
 178                 /* There was a problem reading the mailbox, propagate
 179                  * error value.
 180                  */
 181                 if (unlikely(ret < 0))
 182                         return ERR_PTR(ret);
 183
 184                 return skb_error;
 185         }
 186
 187         cb = can_rx_offload_get_cb(skb);
 188         ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
 189
 190         /* Mailbox was empty. */
 191         if (unlikely(!ret)) {
 192                 kfree_skb(skb);
 193                 return NULL;
 194         }
 195
 196         /* There was a problem reading the mailbox, propagate error value. */
 197         if (unlikely(ret < 0)) {
 198                 kfree_skb(skb);
 199
 200                 offload->dev->stats.rx_dropped++;
 201                 offload->dev->stats.rx_fifo_errors++;
 202
 203                 return ERR_PTR(ret);
 204         }
 205
 206         /* Mailbox was read. */
 207         return skb;
 208 }
 209
 210 int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload,
 211                                          u64 pending)
 212 {
 213         struct sk_buff_head skb_queue;
 214         unsigned int i;
 215
 216         __skb_queue_head_init(&skb_queue);
 217
 218         for (i = offload->mb_first;
 219              can_rx_offload_le(offload, i, offload->mb_last);
 220              can_rx_offload_inc(offload, &i)) {
 221                 struct sk_buff *skb;
 222
 223                 if (!(pending & BIT_ULL(i)))
 224                         continue;
 225
 226                 skb = can_rx_offload_offload_one(offload, i);
 227                 if (IS_ERR_OR_NULL(skb))
 228                         continue;
 229
 230                 __skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare);
 231         }
 232
 233         if (!skb_queue_empty(&skb_queue)) {
 234                 unsigned long flags;
 235                 u32 queue_len;
 236
 237                 spin_lock_irqsave(&offload->skb_queue.lock, flags);
 238                 skb_queue_splice_tail(&skb_queue, &offload->skb_queue);
 239                 spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
 240
 241                 if ((queue_len = skb_queue_len(&offload->skb_queue)) >
 242                     (offload->skb_queue_len_max / 8))
 243                         netdev_dbg(offload->dev, "%s: queue_len=%d\n",
 244                                    __func__, queue_len);
 245
 246                 can_rx_offload_schedule(offload);
 247         }
 248
 249         return skb_queue_len(&skb_queue);
 250 }
 251 EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);
 252
 253 int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
 254 {
 255         struct sk_buff *skb;
 256         int received = 0;
 257
 258         while (1) {
 259                 skb = can_rx_offload_offload_one(offload, 0);
 260                 if (IS_ERR(skb))
 261                         continue;
 262                 if (!skb)
 263                         break;
 264
 265                 skb_queue_tail(&offload->skb_queue, skb);
 266                 received++;
 267         }
 268
 269         if (received)
 270                 can_rx_offload_schedule(offload);
 271
 272         return received;
 273 }
 274 EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);
 275
 276 int can_rx_offload_queue_sorted(struct can_rx_offload *offload,
 277                                 struct sk_buff *skb, u32 timestamp)
 278 {
 279         struct can_rx_offload_cb *cb;
 280         unsigned long flags;
 281
 282         if (skb_queue_len(&offload->skb_queue) >
 283             offload->skb_queue_len_max) {
 284                 kfree_skb(skb);
 285                 return -ENOBUFS;
 286         }
 287
 288         cb = can_rx_offload_get_cb(skb);
 289         cb->timestamp = timestamp;
 290
 291         spin_lock_irqsave(&offload->skb_queue.lock, flags);
 292         __skb_queue_add_sort(&offload->skb_queue, skb, can_rx_offload_compare);
 293         spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
 294
 295         can_rx_offload_schedule(offload);
 296
 297         return 0;
 298 }
 299 EXPORT_SYMBOL_GPL(can_rx_offload_queue_sorted);
 300
 301 unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
 302                                          unsigned int idx, u32 timestamp)
 303 {
 304         struct net_device *dev = offload->dev;
 305         struct net_device_stats *stats = &dev->stats;
 306         struct sk_buff *skb;
 307         u8 len;
 308         int err;
 309
 310         skb = __can_get_echo_skb(dev, idx, &len);
 311         if (!skb)
 312                 return 0;
 313
 314         err = can_rx_offload_queue_sorted(offload, skb, timestamp);
 315         if (err) {
 316                 stats->rx_errors++;
 317                 stats->tx_fifo_errors++;
 318         }
 319
 320         return len;
 321 }
 322 EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb);
 323
 324 int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 325                               struct sk_buff *skb)
 326 {
 327         if (skb_queue_len(&offload->skb_queue) >
 328             offload->skb_queue_len_max) {
 329                 kfree_skb(skb);
 330                 return -ENOBUFS;
 331         }
 332
 333         skb_queue_tail(&offload->skb_queue, skb);
 334         can_rx_offload_schedule(offload);
 335
 336         return 0;
 337 }
 338 EXPORT_SYMBOL_GPL(can_rx_offload_queue_tail);
 339
 340 static int can_rx_offload_init_queue(struct net_device *dev,
 341                                      struct can_rx_offload *offload,
 342                                      unsigned int weight)
 343 {
 344         offload->dev = dev;
 345
 346         /* Limit queue len to 4x the weight (rounted to next power of two) */
 347         offload->skb_queue_len_max = 2 << fls(weight);
 348         offload->skb_queue_len_max *= 4;
 349         skb_queue_head_init(&offload->skb_queue);
 350
 351         can_rx_offload_reset(offload);
 352         netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
 353
 354         dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
 355                 __func__, offload->skb_queue_len_max);
 356
 357         return 0;
 358 }
 359
 360 int can_rx_offload_add_timestamp(struct net_device *dev,
 361                                  struct can_rx_offload *offload)
 362 {
 363         unsigned int weight;
 364
 365         if (offload->mb_first > BITS_PER_LONG_LONG ||
 366             offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
 367                 return -EINVAL;
 368
 369         if (offload->mb_first < offload->mb_last) {
 370                 offload->inc = true;
 371                 weight = offload->mb_last - offload->mb_first;
 372         } else {
 373                 offload->inc = false;
 374                 weight = offload->mb_first - offload->mb_last;
 375         }
 376
 377         return can_rx_offload_init_queue(dev, offload, weight);
 378 }
 379 EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
 380
 381 int can_rx_offload_add_fifo(struct net_device *dev,
 382                             struct can_rx_offload *offload, unsigned int weight)
 383 {
 384         if (!offload->mailbox_read)
 385                 return -EINVAL;
 386
 387         return can_rx_offload_init_queue(dev, offload, weight);
 388 }
 389 EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
 390
 391 void can_rx_offload_enable(struct can_rx_offload *offload)
 392 {
 393         can_rx_offload_reset(offload);
 394         napi_enable(&offload->napi);
 395 }
 396 EXPORT_SYMBOL_GPL(can_rx_offload_enable);
 397
 398 void can_rx_offload_del(struct can_rx_offload *offload)
 399 {
 400         netif_napi_del(&offload->napi);
 401         skb_queue_purge(&offload->skb_queue);
 402 }
 403 EXPORT_SYMBOL_GPL(can_rx_offload_del);
 404
 405 void can_rx_offload_reset(struct can_rx_offload *offload)
 406 {
 407 }
 408 EXPORT_SYMBOL_GPL(can_rx_offload_reset);