summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/dev/rx-offload.c
blob: 7f80d8e1e750a8eed10e11043ced5c5a67e0741f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2014      Protonic Holland,
 *                         David Jander
 * Copyright (C) 2014-2021 Pengutronix,
 *                         Marc Kleine-Budde <kernel@pengutronix.de>
 */

#include <linux/can/dev.h>
#include <linux/can/rx-offload.h>

struct can_rx_offload_cb {
	u32 timestamp;
};

static inline struct can_rx_offload_cb *
can_rx_offload_get_cb(struct sk_buff *skb)
{
	BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));

	return (struct can_rx_offload_cb *)skb->cb;
}

static inline bool
can_rx_offload_le(struct can_rx_offload *offload,
		  unsigned int a, unsigned int b)
{
	if (offload->inc)
		return a <= b;
	else
		return a >= b;
}

static inline unsigned int
can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
{
	if (offload->inc)
		return (*val)++;
	else
		return (*val)--;
}

static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
{
	struct can_rx_offload *offload = container_of(napi,
						      struct can_rx_offload,
						      napi);
	struct net_device *dev = offload->dev;
	struct net_device_stats *stats = &dev->stats;
	struct sk_buff *skb;
	int work_done = 0;

	while ((work_done < quota) &&
	       (skb = skb_dequeue(&offload->skb_queue))) {
		struct can_frame *cf = (struct can_frame *)skb->data;

		work_done++;
		if (!(cf->can_id & CAN_ERR_FLAG)) {
			stats->rx_packets++;
			if (!(cf->can_id & CAN_RTR_FLAG))
				stats->rx_bytes += cf->len;
		}
		netif_receive_skb(skb);
	}

	if (work_done < quota) {
		napi_complete_done(napi, work_done);

		/* Check if there was another interrupt */
		if (!skb_queue_empty(&offload->skb_queue))
			napi_reschedule(&offload->napi);
	}

	can_led_event(offload->dev, CAN_LED_EVENT_RX);

	return work_done;
}

static inline void
__skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
		     int (*compare)(struct sk_buff *a, struct sk_buff *b))
{
	struct sk_buff *pos, *insert = NULL;

	skb_queue_reverse_walk(head, pos) {
		const struct can_rx_offload_cb *cb_pos, *cb_new;

		cb_pos = can_rx_offload_get_cb(pos);
		cb_new = can_rx_offload_get_cb(new);

		netdev_dbg(new->dev,
			   "%s: pos=0x%08x, new=0x%08x, diff=%10d, queue_len=%d\n",
			   __func__,
			   cb_pos->timestamp, cb_new->timestamp,
			   cb_new->timestamp - cb_pos->timestamp,
			   skb_queue_len(head));

		if (compare(pos, new) < 0)
			continue;
		insert = pos;
		break;
	}
	if (!insert)
		__skb_queue_head(head, new);
	else
		__skb_queue_after(head, insert, new);
}

static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
{
	const struct can_rx_offload_cb *cb_a, *cb_b;

	cb_a = can_rx_offload_get_cb(a);
	cb_b = can_rx_offload_get_cb(b);

	/* Subtract two u32 and return result as int, to keep
	 * difference steady around the u32 overflow.
	 */
	return cb_b->timestamp - cb_a->timestamp;
}

/**
 * can_rx_offload_offload_one() - Read one CAN frame from HW
 * @offload: pointer to rx_offload context
 * @n: number of mailbox to read
 *
 * The task of this function is to read a CAN frame from mailbox @n
 * from the device and return the mailbox's content as a struct
 * sk_buff.
 *
 * If the struct can_rx_offload::skb_queue exceeds the maximal queue
 * length (struct can_rx_offload::skb_queue_len_max) or no skb can be
 * allocated, the mailbox contents is discarded by reading it into an
 * overflow buffer. This way the mailbox is marked as free by the
 * driver.
 *
 * Return: A pointer to skb containing the CAN frame on success.
 *
 *         NULL if the mailbox @n is empty.
 *
 *         ERR_PTR() in case of an error
 */
static struct sk_buff *
can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
{
	struct sk_buff *skb;
	struct can_rx_offload_cb *cb;
	bool drop = false;
	u32 timestamp;

	/* If queue is full drop frame */
	if (unlikely(skb_queue_len(&offload->skb_queue) >
		     offload->skb_queue_len_max))
		drop = true;

	skb = offload->mailbox_read(offload, n, &timestamp, drop);
	/* Mailbox was empty. */
	if (unlikely(!skb))
		return NULL;

	/* There was a problem reading the mailbox, propagate
	 * error value.
	 */
	if (IS_ERR(skb)) {
		offload->dev->stats.rx_dropped++;
		offload->dev->stats.rx_fifo_errors++;

		return skb;
	}

	/* Mailbox was read. */
	cb = can_rx_offload_get_cb(skb);
	cb->timestamp = timestamp;

	return skb;
}

int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload,
					 u64 pending)
{
	unsigned int i;
	int received = 0;

	for (i = offload->mb_first;
	     can_rx_offload_le(offload, i, offload->mb_last);
	     can_rx_offload_inc(offload, &i)) {
		struct sk_buff *skb;

		if (!(pending & BIT_ULL(i)))
			continue;

		skb = can_rx_offload_offload_one(offload, i);
		if (IS_ERR_OR_NULL(skb))
			continue;

		__skb_queue_add_sort(&offload->skb_irq_queue, skb,
				     can_rx_offload_compare);
		received++;
	}

	return received;
}
EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);

int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
{
	struct sk_buff *skb;
	int received = 0;

	while (1) {
		skb = can_rx_offload_offload_one(offload, 0);
		if (IS_ERR(skb))
			continue;
		if (!skb)
			break;

		__skb_queue_tail(&offload->skb_irq_queue, skb);
		received++;
	}

	return received;
}
EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);

int can_rx_offload_queue_sorted(struct can_rx_offload *offload,
				struct sk_buff *skb, u32 timestamp)
{
	struct can_rx_offload_cb *cb;

	if (skb_queue_len(&offload->skb_queue) >
	    offload->skb_queue_len_max) {
		dev_kfree_skb_any(skb);
		return -ENOBUFS;
	}

	cb = can_rx_offload_get_cb(skb);
	cb->timestamp = timestamp;

	__skb_queue_add_sort(&offload->skb_irq_queue, skb,
			     can_rx_offload_compare);

	return 0;
}
EXPORT_SYMBOL_GPL(can_rx_offload_queue_sorted);

unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
					 unsigned int idx, u32 timestamp,
					 unsigned int *frame_len_ptr)
{
	struct net_device *dev = offload->dev;
	struct net_device_stats *stats = &dev->stats;
	struct sk_buff *skb;
	u8 len;
	int err;

	skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);
	if (!skb)
		return 0;

	err = can_rx_offload_queue_sorted(offload, skb, timestamp);
	if (err) {
		stats->rx_errors++;
		stats->tx_fifo_errors++;
	}

	return len;
}
EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb);

int can_rx_offload_queue_tail(struct can_rx_offload *offload,
			      struct sk_buff *skb)
{
	if (skb_queue_len(&offload->skb_queue) >
	    offload->skb_queue_len_max) {
		dev_kfree_skb_any(skb);
		return -ENOBUFS;
	}

	__skb_queue_tail(&offload->skb_irq_queue, skb);

	return 0;
}
EXPORT_SYMBOL_GPL(can_rx_offload_queue_tail);

void can_rx_offload_irq_finish(struct can_rx_offload *offload)
{
	unsigned long flags;
	int queue_len;

	if (skb_queue_empty_lockless(&offload->skb_irq_queue))
		return;

	spin_lock_irqsave(&offload->skb_queue.lock, flags);
	skb_queue_splice_tail_init(&offload->skb_irq_queue, &offload->skb_queue);
	spin_unlock_irqrestore(&offload->skb_queue.lock, flags);

	queue_len = skb_queue_len(&offload->skb_queue);
	if (queue_len > offload->skb_queue_len_max / 8)
		netdev_dbg(offload->dev, "%s: queue_len=%d\n",
			   __func__, queue_len);

	napi_schedule(&offload->napi);
}
EXPORT_SYMBOL_GPL(can_rx_offload_irq_finish);

void can_rx_offload_threaded_irq_finish(struct can_rx_offload *offload)
{
	unsigned long flags;
	int queue_len;

	if (skb_queue_empty_lockless(&offload->skb_irq_queue))
		return;

	spin_lock_irqsave(&offload->skb_queue.lock, flags);
	skb_queue_splice_tail_init(&offload->skb_irq_queue, &offload->skb_queue);
	spin_unlock_irqrestore(&offload->skb_queue.lock, flags);

	queue_len = skb_queue_len(&offload->skb_queue);
	if (queue_len > offload->skb_queue_len_max / 8)
		netdev_dbg(offload->dev, "%s: queue_len=%d\n",
			   __func__, queue_len);

	local_bh_disable();
	napi_schedule(&offload->napi);
	local_bh_enable();
}
EXPORT_SYMBOL_GPL(can_rx_offload_threaded_irq_finish);

static int can_rx_offload_init_queue(struct net_device *dev,
				     struct can_rx_offload *offload,
				     unsigned int weight)
{
	offload->dev = dev;

	/* Limit queue len to 4x the weight (rounted to next power of two) */
	offload->skb_queue_len_max = 2 << fls(weight);
	offload->skb_queue_len_max *= 4;
	skb_queue_head_init(&offload->skb_queue);
	__skb_queue_head_init(&offload->skb_irq_queue);

	netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);

	dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
		__func__, offload->skb_queue_len_max);

	return 0;
}

int can_rx_offload_add_timestamp(struct net_device *dev,
				 struct can_rx_offload *offload)
{
	unsigned int weight;

	if (offload->mb_first > BITS_PER_LONG_LONG ||
	    offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
		return -EINVAL;

	if (offload->mb_first < offload->mb_last) {
		offload->inc = true;
		weight = offload->mb_last - offload->mb_first;
	} else {
		offload->inc = false;
		weight = offload->mb_first - offload->mb_last;
	}

	return can_rx_offload_init_queue(dev, offload, weight);
}
EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);

int can_rx_offload_add_fifo(struct net_device *dev,
			    struct can_rx_offload *offload, unsigned int weight)
{
	if (!offload->mailbox_read)
		return -EINVAL;

	return can_rx_offload_init_queue(dev, offload, weight);
}
EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);

int can_rx_offload_add_manual(struct net_device *dev,
			      struct can_rx_offload *offload,
			      unsigned int weight)
{
	if (offload->mailbox_read)
		return -EINVAL;

	return can_rx_offload_init_queue(dev, offload, weight);
}
EXPORT_SYMBOL_GPL(can_rx_offload_add_manual);

void can_rx_offload_enable(struct can_rx_offload *offload)
{
	napi_enable(&offload->napi);
}
EXPORT_SYMBOL_GPL(can_rx_offload_enable);

void can_rx_offload_del(struct can_rx_offload *offload)
{
	netif_napi_del(&offload->napi);
	skb_queue_purge(&offload->skb_queue);
	__skb_queue_purge(&offload->skb_irq_queue);
}
EXPORT_SYMBOL_GPL(can_rx_offload_del);