LXR linux/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
  21struct can_rx_offload_cb {
  22        u32 timestamp;
  23};
  24
  25static 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
  32static 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
  40static 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
  48static 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
  79static 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
 106static 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
 119static 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
 153int 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}
 193EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);
 194
 195int 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}
 210EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);
 211
 212int 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}
 223EXPORT_SYMBOL_GPL(can_rx_offload_irq_queue_err_skb);
 224
 225static 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
 243int 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}
 261EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
 262
 263int 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}
 270EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
 271
 272void can_rx_offload_enable(struct can_rx_offload *offload)
 273{
 274        can_rx_offload_reset(offload);
 275        napi_enable(&offload->napi);
 276}
 277EXPORT_SYMBOL_GPL(can_rx_offload_enable);
 278
 279void can_rx_offload_del(struct can_rx_offload *offload)
 280{
 281        netif_napi_del(&offload->napi);
 282        skb_queue_purge(&offload->skb_queue);
 283}
 284EXPORT_SYMBOL_GPL(can_rx_offload_del);
 285
 286void can_rx_offload_reset(struct can_rx_offload *offload)
 287{
 288}
 289EXPORT_SYMBOL_GPL(can_rx_offload_reset);
 290