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 static struct sk_buff *can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
 120 {
 121         struct sk_buff *skb = NULL;
 122         struct can_rx_offload_cb *cb;
 123         struct can_frame *cf;
 124         int ret;
 125
 126         /* If queue is full or skb not available, read to discard mailbox */
 127         if (likely(skb_queue_len(&offload->skb_queue) <=
 128                    offload->skb_queue_len_max))
 129                 skb = alloc_can_skb(offload->dev, &cf);
 130
 131         if (!skb) {
 132                 struct can_frame cf_overflow;
 133                 u32 timestamp;
 134
 135                 ret = offload->mailbox_read(offload, &cf_overflow,
 136                                             &timestamp, n);
 137                 if (ret)
 138                         offload->dev->stats.rx_dropped++;
 139
 140                 return NULL;
 141         }
 142
 143         cb = can_rx_offload_get_cb(skb);
 144         ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
 145         if (!ret) {
 146                 kfree_skb(skb);
 147                 return NULL;
 148         }
 149
 150         return skb;
 151 }
 152
 153 int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pending)
 154 {
 155         struct sk_buff_head skb_queue;
 156         unsigned int i;
 157
 158         __skb_queue_head_init(&skb_queue);
 159
 160         for (i = offload->mb_first;
 161              can_rx_offload_le(offload, i, offload->mb_last);
 162              can_rx_offload_inc(offload, &i)) {
 163                 struct sk_buff *skb;
 164
 165                 if (!(pending & BIT_ULL(i)))
 166                         continue;
 167
 168                 skb = can_rx_offload_offload_one(offload, i);
 169                 if (!skb)
 170                         break;
 171
 172                 __skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare);
 173         }
 174
 175         if (!skb_queue_empty(&skb_queue)) {
 176                 unsigned long flags;
 177                 u32 queue_len;
 178
 179                 spin_lock_irqsave(&offload->skb_queue.lock, flags);
 180                 skb_queue_splice_tail(&skb_queue, &offload->skb_queue);
 181                 spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
 182
 183                 if ((queue_len = skb_queue_len(&offload->skb_queue)) >
 184                     (offload->skb_queue_len_max / 8))
 185                         netdev_dbg(offload->dev, "%s: queue_len=%d\n",
 186                                    __func__, queue_len);
 187
 188                 can_rx_offload_schedule(offload);
 189         }
 190
 191         return skb_queue_len(&skb_queue);
 192 }
 193 EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);
 194
 195 int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
 196 {
 197         struct sk_buff *skb;
 198         int received = 0;
 199
 200         while ((skb = can_rx_offload_offload_one(offload, 0))) {
 201                 skb_queue_tail(&offload->skb_queue, skb);
 202                 received++;
 203         }
 204
 205         if (received)
 206                 can_rx_offload_schedule(offload);
 207
 208         return received;
 209 }
 210 EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);
 211
 212 int can_rx_offload_irq_queue_err_skb(struct can_rx_offload *offload, struct sk_buff *skb)
 213 {
 214         if (skb_queue_len(&offload->skb_queue) >
 215             offload->skb_queue_len_max)
 216                 return -ENOMEM;
 217
 218         skb_queue_tail(&offload->skb_queue, skb);
 219         can_rx_offload_schedule(offload);
 220
 221         return 0;
 222 }
 223 EXPORT_SYMBOL_GPL(can_rx_offload_irq_queue_err_skb);
 224
 225 static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
 226 {
 227         offload->dev = dev;
 228
 229         /* Limit queue len to 4x the weight (rounted to next power of two) */
 230         offload->skb_queue_len_max = 2 << fls(weight);
 231         offload->skb_queue_len_max *= 4;
 232         skb_queue_head_init(&offload->skb_queue);
 233
 234         can_rx_offload_reset(offload);
 235         netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
 236
 237         dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
 238                 __func__, offload->skb_queue_len_max);
 239
 240         return 0;
 241 }
 242
 243 int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *offload)
 244 {
 245         unsigned int weight;
 246
 247         if (offload->mb_first > BITS_PER_LONG_LONG ||
 248             offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
 249                 return -EINVAL;
 250
 251         if (offload->mb_first < offload->mb_last) {
 252                 offload->inc = true;
 253                 weight = offload->mb_last - offload->mb_first;
 254         } else {
 255                 offload->inc = false;
 256                 weight = offload->mb_first - offload->mb_last;
 257         }
 258
 259         return can_rx_offload_init_queue(dev, offload, weight);
 260 }
 261 EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
 262
 263 int can_rx_offload_add_fifo(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
 264 {
 265         if (!offload->mailbox_read)
 266                 return -EINVAL;
 267
 268         return can_rx_offload_init_queue(dev, offload, weight);
 269 }
 270 EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
 271
 272 void can_rx_offload_enable(struct can_rx_offload *offload)
 273 {
 274         can_rx_offload_reset(offload);
 275         napi_enable(&offload->napi);
 276 }
 277 EXPORT_SYMBOL_GPL(can_rx_offload_enable);
 278
 279 void can_rx_offload_del(struct can_rx_offload *offload)
 280 {
 281         netif_napi_del(&offload->napi);
 282         skb_queue_purge(&offload->skb_queue);
 283 }
 284 EXPORT_SYMBOL_GPL(can_rx_offload_del);
 285
 286 void can_rx_offload_reset(struct can_rx_offload *offload)
 287 {
 288 }
 289 EXPORT_SYMBOL_GPL(can_rx_offload_reset);