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);