![Marc Kleine-Budde](/assets/img/avatar_default.png)
Some CAN controllers don't implement a FIFO in hardware, but fill their mailboxes in a particular order (from lowest to highest or highest to lowest). This makes problems to read the frames in the correct order from the hardware, as new frames might be filled into just read (low) mailboxes. This gets worse, when following new frames are received into not read (higher) mailboxes. On the bright side some these CAN controllers put a timestamp on each received CAN frame. This patch adds support to offload CAN frames in interrupt context, order them by timestamp and then transmitted in a NAPI context. Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
290 lines
7.4 KiB
C
290 lines
7.4 KiB
C
/*
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* Copyright (c) 2014 David Jander, Protonic Holland
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* Copyright (C) 2014-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the version 2 of the GNU General Public License
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* as published by the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/can/dev.h>
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#include <linux/can/rx-offload.h>
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struct can_rx_offload_cb {
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u32 timestamp;
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};
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static inline struct can_rx_offload_cb *can_rx_offload_get_cb(struct sk_buff *skb)
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{
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BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));
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return (struct can_rx_offload_cb *)skb->cb;
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}
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static inline bool can_rx_offload_le(struct can_rx_offload *offload, unsigned int a, unsigned int b)
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{
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if (offload->inc)
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return a <= b;
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else
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return a >= b;
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}
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static inline unsigned int can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
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{
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if (offload->inc)
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return (*val)++;
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else
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return (*val)--;
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}
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static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
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{
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struct can_rx_offload *offload = container_of(napi, struct can_rx_offload, napi);
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struct net_device *dev = offload->dev;
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struct net_device_stats *stats = &dev->stats;
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struct sk_buff *skb;
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int work_done = 0;
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while ((work_done < quota) &&
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(skb = skb_dequeue(&offload->skb_queue))) {
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struct can_frame *cf = (struct can_frame *)skb->data;
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work_done++;
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stats->rx_packets++;
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stats->rx_bytes += cf->can_dlc;
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netif_receive_skb(skb);
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}
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if (work_done < quota) {
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napi_complete_done(napi, work_done);
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/* Check if there was another interrupt */
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if (!skb_queue_empty(&offload->skb_queue))
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napi_reschedule(&offload->napi);
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}
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can_led_event(offload->dev, CAN_LED_EVENT_RX);
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return work_done;
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}
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static inline void __skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
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int (*compare)(struct sk_buff *a, struct sk_buff *b))
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{
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struct sk_buff *pos, *insert = (struct sk_buff *)head;
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skb_queue_reverse_walk(head, pos) {
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const struct can_rx_offload_cb *cb_pos, *cb_new;
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cb_pos = can_rx_offload_get_cb(pos);
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cb_new = can_rx_offload_get_cb(new);
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netdev_dbg(new->dev,
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"%s: pos=0x%08x, new=0x%08x, diff=%10d, queue_len=%d\n",
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__func__,
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cb_pos->timestamp, cb_new->timestamp,
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cb_new->timestamp - cb_pos->timestamp,
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skb_queue_len(head));
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if (compare(pos, new) < 0)
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continue;
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insert = pos;
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break;
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}
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__skb_queue_after(head, insert, new);
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}
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static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
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{
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const struct can_rx_offload_cb *cb_a, *cb_b;
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cb_a = can_rx_offload_get_cb(a);
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cb_b = can_rx_offload_get_cb(b);
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/* Substract two u32 and return result as int, to keep
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* difference steady around the u32 overflow.
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*/
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return cb_b->timestamp - cb_a->timestamp;
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}
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static struct sk_buff *can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
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{
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struct sk_buff *skb = NULL;
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struct can_rx_offload_cb *cb;
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struct can_frame *cf;
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int ret;
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/* If queue is full or skb not available, read to discard mailbox */
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if (likely(skb_queue_len(&offload->skb_queue) <=
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offload->skb_queue_len_max))
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skb = alloc_can_skb(offload->dev, &cf);
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if (!skb) {
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struct can_frame cf_overflow;
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u32 timestamp;
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ret = offload->mailbox_read(offload, &cf_overflow,
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×tamp, n);
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if (ret)
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offload->dev->stats.rx_dropped++;
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return NULL;
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}
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cb = can_rx_offload_get_cb(skb);
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ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
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if (!ret) {
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kfree_skb(skb);
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return NULL;
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}
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return skb;
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}
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int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pending)
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{
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struct sk_buff_head skb_queue;
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unsigned int i;
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__skb_queue_head_init(&skb_queue);
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for (i = offload->mb_first;
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can_rx_offload_le(offload, i, offload->mb_last);
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can_rx_offload_inc(offload, &i)) {
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struct sk_buff *skb;
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if (!(pending & BIT_ULL(i)))
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continue;
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skb = can_rx_offload_offload_one(offload, i);
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if (!skb)
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break;
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__skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare);
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}
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if (!skb_queue_empty(&skb_queue)) {
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unsigned long flags;
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u32 queue_len;
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spin_lock_irqsave(&offload->skb_queue.lock, flags);
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skb_queue_splice_tail(&skb_queue, &offload->skb_queue);
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spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
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if ((queue_len = skb_queue_len(&offload->skb_queue)) >
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(offload->skb_queue_len_max / 8))
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netdev_dbg(offload->dev, "%s: queue_len=%d\n",
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__func__, queue_len);
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can_rx_offload_schedule(offload);
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}
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return skb_queue_len(&skb_queue);
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);
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int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
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{
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struct sk_buff *skb;
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int received = 0;
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while ((skb = can_rx_offload_offload_one(offload, 0))) {
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skb_queue_tail(&offload->skb_queue, skb);
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received++;
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}
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if (received)
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can_rx_offload_schedule(offload);
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return received;
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);
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int can_rx_offload_irq_queue_err_skb(struct can_rx_offload *offload, struct sk_buff *skb)
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{
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if (skb_queue_len(&offload->skb_queue) >
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offload->skb_queue_len_max)
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return -ENOMEM;
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skb_queue_tail(&offload->skb_queue, skb);
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can_rx_offload_schedule(offload);
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return 0;
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_irq_queue_err_skb);
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static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
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{
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offload->dev = dev;
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/* Limit queue len to 4x the weight (rounted to next power of two) */
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offload->skb_queue_len_max = 2 << fls(weight);
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offload->skb_queue_len_max *= 4;
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skb_queue_head_init(&offload->skb_queue);
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can_rx_offload_reset(offload);
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netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
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dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
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__func__, offload->skb_queue_len_max);
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return 0;
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}
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int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *offload)
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{
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unsigned int weight;
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if (offload->mb_first > BITS_PER_LONG_LONG ||
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offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
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return -EINVAL;
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if (offload->mb_first < offload->mb_last) {
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offload->inc = true;
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weight = offload->mb_last - offload->mb_first;
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} else {
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offload->inc = false;
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weight = offload->mb_first - offload->mb_last;
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}
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return can_rx_offload_init_queue(dev, offload, weight);;
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
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int can_rx_offload_add_fifo(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
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{
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if (!offload->mailbox_read)
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return -EINVAL;
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return can_rx_offload_init_queue(dev, offload, weight);
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
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void can_rx_offload_enable(struct can_rx_offload *offload)
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{
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can_rx_offload_reset(offload);
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napi_enable(&offload->napi);
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_enable);
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void can_rx_offload_del(struct can_rx_offload *offload)
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{
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netif_napi_del(&offload->napi);
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skb_queue_purge(&offload->skb_queue);
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_del);
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void can_rx_offload_reset(struct can_rx_offload *offload)
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{
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}
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EXPORT_SYMBOL_GPL(can_rx_offload_reset);
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