drivers/net/can/rx-offload.c

   1 /*
   2  * Copyright (c) 2014 David Jander, Protonic Holland
   3  * Copyright (C) 2014-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the version 2 of the GNU General Public License
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/can/dev.h>
  19 #include <linux/can/rx-offload.h>
  20
  21 struct can_rx_offload_cb {
  22         u32 timestamp;
  23 };
  24
  25 static inline struct can_rx_offload_cb *can_rx_offload_get_cb(struct sk_buff *skb)
  26 {
  27         BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));
  28
  29         return (struct can_rx_offload_cb *)skb->cb;
  30 }
  31
  32 static inline bool can_rx_offload_le(struct can_rx_offload *offload, unsigned int a, unsigned int b)
  33 {
  34         if (offload->inc)
  35                 return a <= b;
  36         else
  37                 return a >= b;
  38 }
  39
  40 static inline unsigned int can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
  41 {
  42         if (offload->inc)
  43                 return (*val)++;
  44         else
  45                 return (*val)--;
  46 }
  47
  48 static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
  49 {
  50         struct can_rx_offload *offload = container_of(napi, struct can_rx_offload, napi);
  51         struct net_device *dev = offload->dev;
  52         struct net_device_stats *stats = &dev->stats;
  53         struct sk_buff *skb;
  54         int work_done = 0;
  55
  56         while ((work_done < quota) &&
  57                (skb = skb_dequeue(&offload->skb_queue))) {
  58                 struct can_frame *cf = (struct can_frame *)skb->data;
  59
  60                 work_done++;
  61                 stats->rx_packets++;
  62                 stats->rx_bytes += cf->can_dlc;
  63                 netif_receive_skb(skb);
  64         }
  65
  66         if (work_done < quota) {
  67                 napi_complete_done(napi, work_done);
  68
  69                 /* Check if there was another interrupt */
  70                 if (!skb_queue_empty(&offload->skb_queue))
  71                         napi_reschedule(&offload->napi);
  72         }
  73
  74         can_led_event(offload->dev, CAN_LED_EVENT_RX);
  75
  76         return work_done;
  77 }
  78
  79 static inline void __skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
  80                                         int (*compare)(struct sk_buff *a, struct sk_buff *b))
  81 {
  82         struct sk_buff *pos, *insert = (struct sk_buff *)head;
  83
  84         skb_queue_reverse_walk(head, pos) {
  85                 const struct can_rx_offload_cb *cb_pos, *cb_new;
  86
  87                 cb_pos = can_rx_offload_get_cb(pos);
  88                 cb_new = can_rx_offload_get_cb(new);
  89
  90                 netdev_dbg(new->dev,
  91                            "%s: pos=0x%08x, new=0x%08x, diff=%10d, queue_len=%d\n",
  92                            __func__,
  93                            cb_pos->timestamp, cb_new->timestamp,
  94                            cb_new->timestamp - cb_pos->timestamp,
  95                            skb_queue_len(head));
  96
  97                 if (compare(pos, new) < 0)
  98                         continue;
  99                 insert = pos;
 100                 break;
 101         }
 102
 103         __skb_queue_after(head, insert, new);
 104 }
 105
 106 static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
 107 {
 108         const struct can_rx_offload_cb *cb_a, *cb_b;
 109
 110         cb_a = can_rx_offload_get_cb(a);
 111         cb_b = can_rx_offload_get_cb(b);
 112
 113         /* Substract two u32 and return result as int, to keep
 114          * difference steady around the u32 overflow.
 115          */
 116         return cb_b->timestamp - cb_a->timestamp;
 117 }
 118
 119 /**
 120  * can_rx_offload_offload_one() - Read one CAN frame from HW
 121  * @offload: pointer to rx_offload context
 122  * @n: number of mailbox to read
 123  *
 124  * The task of this function is to read a CAN frame from mailbox @n
 125  * from the device and return the mailbox's content as a struct
 126  * sk_buff.
 127  *
 128  * If the struct can_rx_offload::skb_queue exceeds the maximal queue
 129  * length (struct can_rx_offload::skb_queue_len_max) or no skb can be
 130  * allocated, the mailbox contents is discarded by reading it into an
 131  * overflow buffer. This way the mailbox is marked as free by the
 132  * driver.
 133  *
 134  * Return: A pointer to skb containing the CAN frame on success.
 135  *
 136  *         NULL if the mailbox @n is empty.
 137  *
 138  *         ERR_PTR() in case of an error
 139  */
 140 static struct sk_buff *
 141 can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
 142 {
 143         struct sk_buff *skb = NULL, *skb_error = NULL;
 144         struct can_rx_offload_cb *cb;
 145         struct can_frame *cf;
 146         int ret;
 147
 148         if (likely(skb_queue_len(&offload->skb_queue) <
 149                    offload->skb_queue_len_max)) {
 150                 skb = alloc_can_skb(offload->dev, &cf);
 151                 if (unlikely(!skb))
 152                         skb_error = ERR_PTR(-ENOMEM);   /* skb alloc failed */
 153         } else {
 154                 skb_error = ERR_PTR(-ENOBUFS);          /* skb_queue is full */
 155         }
 156
 157         /* If queue is full or skb not available, drop by reading into
 158          * overflow buffer.
 159          */
 160         if (unlikely(skb_error)) {
 161                 struct can_frame cf_overflow;
 162                 u32 timestamp;
 163
 164                 ret = offload->mailbox_read(offload, &cf_overflow,
 165                                             &timestamp, n);
 166
 167                 /* Mailbox was empty. */
 168                 if (unlikely(!ret))
 169                         return NULL;
 170
 171                 /* Mailbox has been read and we're dropping it or
 172                  * there was a problem reading the mailbox.
 173                  *
 174                  * Increment error counters in any case.
 175                  */
 176                 offload->dev->stats.rx_dropped++;
 177                 offload->dev->stats.rx_fifo_errors++;
 178
 179                 /* There was a problem reading the mailbox, propagate
 180                  * error value.
 181                  */
 182                 if (unlikely(ret < 0))
 183                         return ERR_PTR(ret);
 184
 185                 return skb_error;
 186         }
 187
 188         cb = can_rx_offload_get_cb(skb);
 189         ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
 190
 191         /* Mailbox was empty. */
 192         if (unlikely(!ret)) {
 193                 kfree_skb(skb);
 194                 return NULL;
 195         }
 196
 197         /* There was a problem reading the mailbox, propagate error value. */
 198         if (unlikely(ret < 0)) {
 199                 kfree_skb(skb);
 200
 201                 offload->dev->stats.rx_dropped++;
 202                 offload->dev->stats.rx_fifo_errors++;
 203
 204                 return ERR_PTR(ret);
 205         }
 206
 207         /* Mailbox was read. */
 208         return skb;
 209 }
 210
 211 int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, 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                 dev_kfree_skb_any(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                 dev_kfree_skb_any(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, struct can_rx_offload *offload, unsigned int weight)
 341 {
 342         offload->dev = dev;
 343
 344         /* Limit queue len to 4x the weight (rounted to next power of two) */
 345         offload->skb_queue_len_max = 2 << fls(weight);
 346         offload->skb_queue_len_max *= 4;
 347         skb_queue_head_init(&offload->skb_queue);
 348
 349         can_rx_offload_reset(offload);
 350         netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
 351
 352         dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
 353                 __func__, offload->skb_queue_len_max);
 354
 355         return 0;
 356 }
 357
 358 int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *offload)
 359 {
 360         unsigned int weight;
 361
 362         if (offload->mb_first > BITS_PER_LONG_LONG ||
 363             offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
 364                 return -EINVAL;
 365
 366         if (offload->mb_first < offload->mb_last) {
 367                 offload->inc = true;
 368                 weight = offload->mb_last - offload->mb_first;
 369         } else {
 370                 offload->inc = false;
 371                 weight = offload->mb_first - offload->mb_last;
 372         }
 373
 374         return can_rx_offload_init_queue(dev, offload, weight);
 375 }
 376 EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
 377
 378 int can_rx_offload_add_fifo(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
 379 {
 380         if (!offload->mailbox_read)
 381                 return -EINVAL;
 382
 383         return can_rx_offload_init_queue(dev, offload, weight);
 384 }
 385 EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
 386
 387 void can_rx_offload_enable(struct can_rx_offload *offload)
 388 {
 389         can_rx_offload_reset(offload);
 390         napi_enable(&offload->napi);
 391 }
 392 EXPORT_SYMBOL_GPL(can_rx_offload_enable);
 393
 394 void can_rx_offload_del(struct can_rx_offload *offload)
 395 {
 396         netif_napi_del(&offload->napi);
 397         skb_queue_purge(&offload->skb_queue);
 398 }
 399 EXPORT_SYMBOL_GPL(can_rx_offload_del);
 400
 401 void can_rx_offload_reset(struct can_rx_offload *offload)
 402 {
 403 }
 404 EXPORT_SYMBOL_GPL(can_rx_offload_reset);