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