1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /* Copyright (c) 2019-2020 Marvell International Ltd. All rights reserved */
3 
4 #include <linux/bitfield.h>
5 #include <linux/dmapool.h>
6 #include <linux/etherdevice.h>
7 #include <linux/if_vlan.h>
8 #include <linux/of_address.h>
9 #include <linux/of_device.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 
13 #include "prestera_dsa.h"
14 #include "prestera.h"
15 #include "prestera_hw.h"
16 #include "prestera_rxtx.h"
17 #include "prestera_devlink.h"
18 
19 #define PRESTERA_SDMA_WAIT_MUL		10
20 
21 struct prestera_sdma_desc {
22 	__le32 word1;
23 	__le32 word2;
24 	__le32 buff;
25 	__le32 next;
26 } __packed __aligned(16);
27 
28 #define PRESTERA_SDMA_BUFF_SIZE_MAX	1544
29 
30 #define PRESTERA_SDMA_RX_DESC_PKT_LEN(desc) \
31 	((le32_to_cpu((desc)->word2) >> 16) & GENMASK(13, 0))
32 
33 #define PRESTERA_SDMA_RX_DESC_OWNER(desc) \
34 	((le32_to_cpu((desc)->word1) & BIT(31)) >> 31)
35 
36 #define PRESTERA_SDMA_RX_DESC_IS_RCVD(desc) \
37 	(PRESTERA_SDMA_RX_DESC_OWNER(desc) == PRESTERA_SDMA_RX_DESC_CPU_OWN)
38 
39 #define PRESTERA_SDMA_RX_DESC_CPU_OWN	0
40 #define PRESTERA_SDMA_RX_DESC_DMA_OWN	1
41 
42 #define PRESTERA_SDMA_RX_QUEUE_NUM	8
43 
44 #define PRESTERA_SDMA_RX_DESC_PER_Q	1000
45 
46 #define PRESTERA_SDMA_TX_DESC_PER_Q	1000
47 #define PRESTERA_SDMA_TX_MAX_BURST	64
48 
49 #define PRESTERA_SDMA_TX_DESC_OWNER(desc) \
50 	((le32_to_cpu((desc)->word1) & BIT(31)) >> 31)
51 
52 #define PRESTERA_SDMA_TX_DESC_CPU_OWN	0
53 #define PRESTERA_SDMA_TX_DESC_DMA_OWN	1U
54 
55 #define PRESTERA_SDMA_TX_DESC_IS_SENT(desc) \
56 	(PRESTERA_SDMA_TX_DESC_OWNER(desc) == PRESTERA_SDMA_TX_DESC_CPU_OWN)
57 
58 #define PRESTERA_SDMA_TX_DESC_LAST	BIT(20)
59 #define PRESTERA_SDMA_TX_DESC_FIRST	BIT(21)
60 #define PRESTERA_SDMA_TX_DESC_CALC_CRC	BIT(12)
61 
62 #define PRESTERA_SDMA_TX_DESC_SINGLE	\
63 	(PRESTERA_SDMA_TX_DESC_FIRST | PRESTERA_SDMA_TX_DESC_LAST)
64 
65 #define PRESTERA_SDMA_TX_DESC_INIT	\
66 	(PRESTERA_SDMA_TX_DESC_SINGLE | PRESTERA_SDMA_TX_DESC_CALC_CRC)
67 
68 #define PRESTERA_SDMA_RX_INTR_MASK_REG		0x2814
69 #define PRESTERA_SDMA_RX_QUEUE_STATUS_REG	0x2680
70 #define PRESTERA_SDMA_RX_QUEUE_DESC_REG(n)	(0x260C + (n) * 16)
71 
72 #define PRESTERA_SDMA_TX_QUEUE_DESC_REG		0x26C0
73 #define PRESTERA_SDMA_TX_QUEUE_START_REG	0x2868
74 
75 struct prestera_sdma_buf {
76 	struct prestera_sdma_desc *desc;
77 	dma_addr_t desc_dma;
78 	struct sk_buff *skb;
79 	dma_addr_t buf_dma;
80 	bool is_used;
81 };
82 
83 struct prestera_rx_ring {
84 	struct prestera_sdma_buf *bufs;
85 	int next_rx;
86 };
87 
88 struct prestera_tx_ring {
89 	struct prestera_sdma_buf *bufs;
90 	int next_tx;
91 	int max_burst;
92 	int burst;
93 };
94 
95 struct prestera_sdma {
96 	struct prestera_rx_ring rx_ring[PRESTERA_SDMA_RX_QUEUE_NUM];
97 	struct prestera_tx_ring tx_ring;
98 	struct prestera_switch *sw;
99 	struct dma_pool *desc_pool;
100 	struct work_struct tx_work;
101 	struct napi_struct rx_napi;
102 	struct net_device napi_dev;
103 	u32 map_addr;
104 	u64 dma_mask;
105 	/* protect SDMA with concurrrent access from multiple CPUs */
106 	spinlock_t tx_lock;
107 };
108 
109 struct prestera_rxtx {
110 	struct prestera_sdma sdma;
111 };
112 
113 static int prestera_sdma_buf_init(struct prestera_sdma *sdma,
114 				  struct prestera_sdma_buf *buf)
115 {
116 	struct prestera_sdma_desc *desc;
117 	dma_addr_t dma;
118 
119 	desc = dma_pool_alloc(sdma->desc_pool, GFP_DMA | GFP_KERNEL, &dma);
120 	if (!desc)
121 		return -ENOMEM;
122 
123 	buf->buf_dma = DMA_MAPPING_ERROR;
124 	buf->desc_dma = dma;
125 	buf->desc = desc;
126 	buf->skb = NULL;
127 
128 	return 0;
129 }
130 
131 static u32 prestera_sdma_map(struct prestera_sdma *sdma, dma_addr_t pa)
132 {
133 	return sdma->map_addr + pa;
134 }
135 
136 static void prestera_sdma_rx_desc_init(struct prestera_sdma *sdma,
137 				       struct prestera_sdma_desc *desc,
138 				       dma_addr_t buf)
139 {
140 	u32 word = le32_to_cpu(desc->word2);
141 
142 	u32p_replace_bits(&word, PRESTERA_SDMA_BUFF_SIZE_MAX, GENMASK(15, 0));
143 	desc->word2 = cpu_to_le32(word);
144 
145 	desc->buff = cpu_to_le32(prestera_sdma_map(sdma, buf));
146 
147 	/* make sure buffer is set before reset the descriptor */
148 	wmb();
149 
150 	desc->word1 = cpu_to_le32(0xA0000000);
151 }
152 
153 static void prestera_sdma_rx_desc_set_next(struct prestera_sdma *sdma,
154 					   struct prestera_sdma_desc *desc,
155 					   dma_addr_t next)
156 {
157 	desc->next = cpu_to_le32(prestera_sdma_map(sdma, next));
158 }
159 
160 static int prestera_sdma_rx_skb_alloc(struct prestera_sdma *sdma,
161 				      struct prestera_sdma_buf *buf)
162 {
163 	struct device *dev = sdma->sw->dev->dev;
164 	struct sk_buff *skb;
165 	dma_addr_t dma;
166 
167 	skb = alloc_skb(PRESTERA_SDMA_BUFF_SIZE_MAX, GFP_DMA | GFP_ATOMIC);
168 	if (!skb)
169 		return -ENOMEM;
170 
171 	dma = dma_map_single(dev, skb->data, skb->len, DMA_FROM_DEVICE);
172 	if (dma_mapping_error(dev, dma))
173 		goto err_dma_map;
174 
175 	if (buf->skb)
176 		dma_unmap_single(dev, buf->buf_dma, buf->skb->len,
177 				 DMA_FROM_DEVICE);
178 
179 	buf->buf_dma = dma;
180 	buf->skb = skb;
181 
182 	return 0;
183 
184 err_dma_map:
185 	kfree_skb(skb);
186 
187 	return -ENOMEM;
188 }
189 
190 static struct sk_buff *prestera_sdma_rx_skb_get(struct prestera_sdma *sdma,
191 						struct prestera_sdma_buf *buf)
192 {
193 	dma_addr_t buf_dma = buf->buf_dma;
194 	struct sk_buff *skb = buf->skb;
195 	u32 len = skb->len;
196 	int err;
197 
198 	err = prestera_sdma_rx_skb_alloc(sdma, buf);
199 	if (err) {
200 		buf->buf_dma = buf_dma;
201 		buf->skb = skb;
202 
203 		skb = alloc_skb(skb->len, GFP_ATOMIC);
204 		if (skb) {
205 			skb_put(skb, len);
206 			skb_copy_from_linear_data(buf->skb, skb->data, len);
207 		}
208 	}
209 
210 	prestera_sdma_rx_desc_init(sdma, buf->desc, buf->buf_dma);
211 
212 	return skb;
213 }
214 
215 static int prestera_rxtx_process_skb(struct prestera_sdma *sdma,
216 				     struct sk_buff *skb)
217 {
218 	struct prestera_port *port;
219 	struct prestera_dsa dsa;
220 	u32 hw_port, dev_id;
221 	u8 cpu_code;
222 	int err;
223 
224 	skb_pull(skb, ETH_HLEN);
225 
226 	/* ethertype field is part of the dsa header */
227 	err = prestera_dsa_parse(&dsa, skb->data - ETH_TLEN);
228 	if (err)
229 		return err;
230 
231 	dev_id = dsa.hw_dev_num;
232 	hw_port = dsa.port_num;
233 
234 	port = prestera_port_find_by_hwid(sdma->sw, dev_id, hw_port);
235 	if (unlikely(!port)) {
236 		dev_warn_ratelimited(prestera_dev(sdma->sw), "received pkt for non-existent port(%u, %u)\n",
237 				     dev_id, hw_port);
238 		return -ENOENT;
239 	}
240 
241 	if (unlikely(!pskb_may_pull(skb, PRESTERA_DSA_HLEN)))
242 		return -EINVAL;
243 
244 	/* remove DSA tag and update checksum */
245 	skb_pull_rcsum(skb, PRESTERA_DSA_HLEN);
246 
247 	memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - PRESTERA_DSA_HLEN,
248 		ETH_ALEN * 2);
249 
250 	skb_push(skb, ETH_HLEN);
251 
252 	skb->protocol = eth_type_trans(skb, port->dev);
253 
254 	if (dsa.vlan.is_tagged) {
255 		u16 tci = dsa.vlan.vid & VLAN_VID_MASK;
256 
257 		tci |= dsa.vlan.vpt << VLAN_PRIO_SHIFT;
258 		if (dsa.vlan.cfi_bit)
259 			tci |= VLAN_CFI_MASK;
260 
261 		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), tci);
262 	}
263 
264 	cpu_code = dsa.cpu_code;
265 	prestera_devlink_trap_report(port, skb, cpu_code);
266 
267 	return 0;
268 }
269 
270 static int prestera_sdma_next_rx_buf_idx(int buf_idx)
271 {
272 	return (buf_idx + 1) % PRESTERA_SDMA_RX_DESC_PER_Q;
273 }
274 
275 static int prestera_sdma_rx_poll(struct napi_struct *napi, int budget)
276 {
277 	int qnum = PRESTERA_SDMA_RX_QUEUE_NUM;
278 	unsigned int rxq_done_map = 0;
279 	struct prestera_sdma *sdma;
280 	struct list_head rx_list;
281 	unsigned int qmask;
282 	int pkts_done = 0;
283 	int q;
284 
285 	qnum = PRESTERA_SDMA_RX_QUEUE_NUM;
286 	qmask = GENMASK(qnum - 1, 0);
287 
288 	INIT_LIST_HEAD(&rx_list);
289 
290 	sdma = container_of(napi, struct prestera_sdma, rx_napi);
291 
292 	while (pkts_done < budget && rxq_done_map != qmask) {
293 		for (q = 0; q < qnum && pkts_done < budget; q++) {
294 			struct prestera_rx_ring *ring = &sdma->rx_ring[q];
295 			struct prestera_sdma_desc *desc;
296 			struct prestera_sdma_buf *buf;
297 			int buf_idx = ring->next_rx;
298 			struct sk_buff *skb;
299 
300 			buf = &ring->bufs[buf_idx];
301 			desc = buf->desc;
302 
303 			if (PRESTERA_SDMA_RX_DESC_IS_RCVD(desc)) {
304 				rxq_done_map &= ~BIT(q);
305 			} else {
306 				rxq_done_map |= BIT(q);
307 				continue;
308 			}
309 
310 			pkts_done++;
311 
312 			__skb_trim(buf->skb, PRESTERA_SDMA_RX_DESC_PKT_LEN(desc));
313 
314 			skb = prestera_sdma_rx_skb_get(sdma, buf);
315 			if (!skb)
316 				goto rx_next_buf;
317 
318 			if (unlikely(prestera_rxtx_process_skb(sdma, skb)))
319 				goto rx_next_buf;
320 
321 			list_add_tail(&skb->list, &rx_list);
322 rx_next_buf:
323 			ring->next_rx = prestera_sdma_next_rx_buf_idx(buf_idx);
324 		}
325 	}
326 
327 	if (pkts_done < budget && napi_complete_done(napi, pkts_done))
328 		prestera_write(sdma->sw, PRESTERA_SDMA_RX_INTR_MASK_REG,
329 			       GENMASK(9, 2));
330 
331 	netif_receive_skb_list(&rx_list);
332 
333 	return pkts_done;
334 }
335 
336 static void prestera_sdma_rx_fini(struct prestera_sdma *sdma)
337 {
338 	int qnum = PRESTERA_SDMA_RX_QUEUE_NUM;
339 	int q, b;
340 
341 	/* disable all rx queues */
342 	prestera_write(sdma->sw, PRESTERA_SDMA_RX_QUEUE_STATUS_REG,
343 		       GENMASK(15, 8));
344 
345 	for (q = 0; q < qnum; q++) {
346 		struct prestera_rx_ring *ring = &sdma->rx_ring[q];
347 
348 		if (!ring->bufs)
349 			break;
350 
351 		for (b = 0; b < PRESTERA_SDMA_RX_DESC_PER_Q; b++) {
352 			struct prestera_sdma_buf *buf = &ring->bufs[b];
353 
354 			if (buf->desc_dma)
355 				dma_pool_free(sdma->desc_pool, buf->desc,
356 					      buf->desc_dma);
357 
358 			if (!buf->skb)
359 				continue;
360 
361 			if (buf->buf_dma != DMA_MAPPING_ERROR)
362 				dma_unmap_single(sdma->sw->dev->dev,
363 						 buf->buf_dma, buf->skb->len,
364 						 DMA_FROM_DEVICE);
365 			kfree_skb(buf->skb);
366 		}
367 	}
368 }
369 
370 static int prestera_sdma_rx_init(struct prestera_sdma *sdma)
371 {
372 	int bnum = PRESTERA_SDMA_RX_DESC_PER_Q;
373 	int qnum = PRESTERA_SDMA_RX_QUEUE_NUM;
374 	int err;
375 	int q;
376 
377 	/* disable all rx queues */
378 	prestera_write(sdma->sw, PRESTERA_SDMA_RX_QUEUE_STATUS_REG,
379 		       GENMASK(15, 8));
380 
381 	for (q = 0; q < qnum; q++) {
382 		struct prestera_sdma_buf *head, *tail, *next, *prev;
383 		struct prestera_rx_ring *ring = &sdma->rx_ring[q];
384 
385 		ring->bufs = kmalloc_array(bnum, sizeof(*head), GFP_KERNEL);
386 		if (!ring->bufs)
387 			return -ENOMEM;
388 
389 		ring->next_rx = 0;
390 
391 		tail = &ring->bufs[bnum - 1];
392 		head = &ring->bufs[0];
393 		next = head;
394 		prev = next;
395 
396 		do {
397 			err = prestera_sdma_buf_init(sdma, next);
398 			if (err)
399 				return err;
400 
401 			err = prestera_sdma_rx_skb_alloc(sdma, next);
402 			if (err)
403 				return err;
404 
405 			prestera_sdma_rx_desc_init(sdma, next->desc,
406 						   next->buf_dma);
407 
408 			prestera_sdma_rx_desc_set_next(sdma, prev->desc,
409 						       next->desc_dma);
410 
411 			prev = next;
412 			next++;
413 		} while (prev != tail);
414 
415 		/* join tail with head to make a circular list */
416 		prestera_sdma_rx_desc_set_next(sdma, tail->desc, head->desc_dma);
417 
418 		prestera_write(sdma->sw, PRESTERA_SDMA_RX_QUEUE_DESC_REG(q),
419 			       prestera_sdma_map(sdma, head->desc_dma));
420 	}
421 
422 	/* make sure all rx descs are filled before enabling all rx queues */
423 	wmb();
424 
425 	prestera_write(sdma->sw, PRESTERA_SDMA_RX_QUEUE_STATUS_REG,
426 		       GENMASK(7, 0));
427 
428 	return 0;
429 }
430 
431 static void prestera_sdma_tx_desc_init(struct prestera_sdma *sdma,
432 				       struct prestera_sdma_desc *desc)
433 {
434 	desc->word1 = cpu_to_le32(PRESTERA_SDMA_TX_DESC_INIT);
435 	desc->word2 = 0;
436 }
437 
438 static void prestera_sdma_tx_desc_set_next(struct prestera_sdma *sdma,
439 					   struct prestera_sdma_desc *desc,
440 					   dma_addr_t next)
441 {
442 	desc->next = cpu_to_le32(prestera_sdma_map(sdma, next));
443 }
444 
445 static void prestera_sdma_tx_desc_set_buf(struct prestera_sdma *sdma,
446 					  struct prestera_sdma_desc *desc,
447 					  dma_addr_t buf, size_t len)
448 {
449 	u32 word = le32_to_cpu(desc->word2);
450 
451 	u32p_replace_bits(&word, len + ETH_FCS_LEN, GENMASK(30, 16));
452 
453 	desc->buff = cpu_to_le32(prestera_sdma_map(sdma, buf));
454 	desc->word2 = cpu_to_le32(word);
455 }
456 
457 static void prestera_sdma_tx_desc_xmit(struct prestera_sdma_desc *desc)
458 {
459 	u32 word = le32_to_cpu(desc->word1);
460 
461 	word |= PRESTERA_SDMA_TX_DESC_DMA_OWN << 31;
462 
463 	/* make sure everything is written before enable xmit */
464 	wmb();
465 
466 	desc->word1 = cpu_to_le32(word);
467 }
468 
469 static int prestera_sdma_tx_buf_map(struct prestera_sdma *sdma,
470 				    struct prestera_sdma_buf *buf,
471 				    struct sk_buff *skb)
472 {
473 	struct device *dma_dev = sdma->sw->dev->dev;
474 	dma_addr_t dma;
475 
476 	dma = dma_map_single(dma_dev, skb->data, skb->len, DMA_TO_DEVICE);
477 	if (dma_mapping_error(dma_dev, dma))
478 		return -ENOMEM;
479 
480 	buf->buf_dma = dma;
481 	buf->skb = skb;
482 
483 	return 0;
484 }
485 
486 static void prestera_sdma_tx_buf_unmap(struct prestera_sdma *sdma,
487 				       struct prestera_sdma_buf *buf)
488 {
489 	struct device *dma_dev = sdma->sw->dev->dev;
490 
491 	dma_unmap_single(dma_dev, buf->buf_dma, buf->skb->len, DMA_TO_DEVICE);
492 }
493 
494 static void prestera_sdma_tx_recycle_work_fn(struct work_struct *work)
495 {
496 	int bnum = PRESTERA_SDMA_TX_DESC_PER_Q;
497 	struct prestera_tx_ring *tx_ring;
498 	struct prestera_sdma *sdma;
499 	int b;
500 
501 	sdma = container_of(work, struct prestera_sdma, tx_work);
502 
503 	tx_ring = &sdma->tx_ring;
504 
505 	for (b = 0; b < bnum; b++) {
506 		struct prestera_sdma_buf *buf = &tx_ring->bufs[b];
507 
508 		if (!buf->is_used)
509 			continue;
510 
511 		if (!PRESTERA_SDMA_TX_DESC_IS_SENT(buf->desc))
512 			continue;
513 
514 		prestera_sdma_tx_buf_unmap(sdma, buf);
515 		dev_consume_skb_any(buf->skb);
516 		buf->skb = NULL;
517 
518 		/* make sure everything is cleaned up */
519 		wmb();
520 
521 		buf->is_used = false;
522 	}
523 }
524 
525 static int prestera_sdma_tx_init(struct prestera_sdma *sdma)
526 {
527 	struct prestera_sdma_buf *head, *tail, *next, *prev;
528 	struct prestera_tx_ring *tx_ring = &sdma->tx_ring;
529 	int bnum = PRESTERA_SDMA_TX_DESC_PER_Q;
530 	int err;
531 
532 	INIT_WORK(&sdma->tx_work, prestera_sdma_tx_recycle_work_fn);
533 	spin_lock_init(&sdma->tx_lock);
534 
535 	tx_ring->bufs = kmalloc_array(bnum, sizeof(*head), GFP_KERNEL);
536 	if (!tx_ring->bufs)
537 		return -ENOMEM;
538 
539 	tail = &tx_ring->bufs[bnum - 1];
540 	head = &tx_ring->bufs[0];
541 	next = head;
542 	prev = next;
543 
544 	tx_ring->max_burst = PRESTERA_SDMA_TX_MAX_BURST;
545 	tx_ring->burst = tx_ring->max_burst;
546 	tx_ring->next_tx = 0;
547 
548 	do {
549 		err = prestera_sdma_buf_init(sdma, next);
550 		if (err)
551 			return err;
552 
553 		next->is_used = false;
554 
555 		prestera_sdma_tx_desc_init(sdma, next->desc);
556 
557 		prestera_sdma_tx_desc_set_next(sdma, prev->desc,
558 					       next->desc_dma);
559 
560 		prev = next;
561 		next++;
562 	} while (prev != tail);
563 
564 	/* join tail with head to make a circular list */
565 	prestera_sdma_tx_desc_set_next(sdma, tail->desc, head->desc_dma);
566 
567 	/* make sure descriptors are written */
568 	wmb();
569 
570 	prestera_write(sdma->sw, PRESTERA_SDMA_TX_QUEUE_DESC_REG,
571 		       prestera_sdma_map(sdma, head->desc_dma));
572 
573 	return 0;
574 }
575 
576 static void prestera_sdma_tx_fini(struct prestera_sdma *sdma)
577 {
578 	struct prestera_tx_ring *ring = &sdma->tx_ring;
579 	int bnum = PRESTERA_SDMA_TX_DESC_PER_Q;
580 	int b;
581 
582 	cancel_work_sync(&sdma->tx_work);
583 
584 	if (!ring->bufs)
585 		return;
586 
587 	for (b = 0; b < bnum; b++) {
588 		struct prestera_sdma_buf *buf = &ring->bufs[b];
589 
590 		if (buf->desc)
591 			dma_pool_free(sdma->desc_pool, buf->desc,
592 				      buf->desc_dma);
593 
594 		if (!buf->skb)
595 			continue;
596 
597 		dma_unmap_single(sdma->sw->dev->dev, buf->buf_dma,
598 				 buf->skb->len, DMA_TO_DEVICE);
599 
600 		dev_consume_skb_any(buf->skb);
601 	}
602 }
603 
604 static void prestera_rxtx_handle_event(struct prestera_switch *sw,
605 				       struct prestera_event *evt,
606 				       void *arg)
607 {
608 	struct prestera_sdma *sdma = arg;
609 
610 	if (evt->id != PRESTERA_RXTX_EVENT_RCV_PKT)
611 		return;
612 
613 	prestera_write(sdma->sw, PRESTERA_SDMA_RX_INTR_MASK_REG, 0);
614 	napi_schedule(&sdma->rx_napi);
615 }
616 
617 static int prestera_sdma_switch_init(struct prestera_switch *sw)
618 {
619 	struct prestera_sdma *sdma = &sw->rxtx->sdma;
620 	struct device *dev = sw->dev->dev;
621 	struct prestera_rxtx_params p;
622 	int err;
623 
624 	p.use_sdma = true;
625 
626 	err = prestera_hw_rxtx_init(sw, &p);
627 	if (err) {
628 		dev_err(dev, "failed to init rxtx by hw\n");
629 		return err;
630 	}
631 
632 	sdma->dma_mask = dma_get_mask(dev);
633 	sdma->map_addr = p.map_addr;
634 	sdma->sw = sw;
635 
636 	sdma->desc_pool = dma_pool_create("desc_pool", dev,
637 					  sizeof(struct prestera_sdma_desc),
638 					  16, 0);
639 	if (!sdma->desc_pool)
640 		return -ENOMEM;
641 
642 	err = prestera_sdma_rx_init(sdma);
643 	if (err) {
644 		dev_err(dev, "failed to init rx ring\n");
645 		goto err_rx_init;
646 	}
647 
648 	err = prestera_sdma_tx_init(sdma);
649 	if (err) {
650 		dev_err(dev, "failed to init tx ring\n");
651 		goto err_tx_init;
652 	}
653 
654 	err = prestera_hw_event_handler_register(sw, PRESTERA_EVENT_TYPE_RXTX,
655 						 prestera_rxtx_handle_event,
656 						 sdma);
657 	if (err)
658 		goto err_evt_register;
659 
660 	init_dummy_netdev(&sdma->napi_dev);
661 
662 	netif_napi_add(&sdma->napi_dev, &sdma->rx_napi, prestera_sdma_rx_poll, 64);
663 	napi_enable(&sdma->rx_napi);
664 
665 	return 0;
666 
667 err_evt_register:
668 err_tx_init:
669 	prestera_sdma_tx_fini(sdma);
670 err_rx_init:
671 	prestera_sdma_rx_fini(sdma);
672 
673 	dma_pool_destroy(sdma->desc_pool);
674 	return err;
675 }
676 
677 static void prestera_sdma_switch_fini(struct prestera_switch *sw)
678 {
679 	struct prestera_sdma *sdma = &sw->rxtx->sdma;
680 
681 	napi_disable(&sdma->rx_napi);
682 	netif_napi_del(&sdma->rx_napi);
683 	prestera_hw_event_handler_unregister(sw, PRESTERA_EVENT_TYPE_RXTX,
684 					     prestera_rxtx_handle_event);
685 	prestera_sdma_tx_fini(sdma);
686 	prestera_sdma_rx_fini(sdma);
687 	dma_pool_destroy(sdma->desc_pool);
688 }
689 
690 static bool prestera_sdma_is_ready(struct prestera_sdma *sdma)
691 {
692 	return !(prestera_read(sdma->sw, PRESTERA_SDMA_TX_QUEUE_START_REG) & 1);
693 }
694 
695 static int prestera_sdma_tx_wait(struct prestera_sdma *sdma,
696 				 struct prestera_tx_ring *tx_ring)
697 {
698 	int tx_wait_num = PRESTERA_SDMA_WAIT_MUL * tx_ring->max_burst;
699 
700 	do {
701 		if (prestera_sdma_is_ready(sdma))
702 			return 0;
703 
704 		udelay(1);
705 	} while (--tx_wait_num);
706 
707 	return -EBUSY;
708 }
709 
710 static void prestera_sdma_tx_start(struct prestera_sdma *sdma)
711 {
712 	prestera_write(sdma->sw, PRESTERA_SDMA_TX_QUEUE_START_REG, 1);
713 	schedule_work(&sdma->tx_work);
714 }
715 
716 static netdev_tx_t prestera_sdma_xmit(struct prestera_sdma *sdma,
717 				      struct sk_buff *skb)
718 {
719 	struct device *dma_dev = sdma->sw->dev->dev;
720 	struct net_device *dev = skb->dev;
721 	struct prestera_tx_ring *tx_ring;
722 	struct prestera_sdma_buf *buf;
723 	int err;
724 
725 	spin_lock(&sdma->tx_lock);
726 
727 	tx_ring = &sdma->tx_ring;
728 
729 	buf = &tx_ring->bufs[tx_ring->next_tx];
730 	if (buf->is_used) {
731 		schedule_work(&sdma->tx_work);
732 		goto drop_skb;
733 	}
734 
735 	if (unlikely(eth_skb_pad(skb)))
736 		goto drop_skb_nofree;
737 
738 	err = prestera_sdma_tx_buf_map(sdma, buf, skb);
739 	if (err)
740 		goto drop_skb;
741 
742 	prestera_sdma_tx_desc_set_buf(sdma, buf->desc, buf->buf_dma, skb->len);
743 
744 	dma_sync_single_for_device(dma_dev, buf->buf_dma, skb->len,
745 				   DMA_TO_DEVICE);
746 
747 	if (tx_ring->burst) {
748 		tx_ring->burst--;
749 	} else {
750 		tx_ring->burst = tx_ring->max_burst;
751 
752 		err = prestera_sdma_tx_wait(sdma, tx_ring);
753 		if (err)
754 			goto drop_skb_unmap;
755 	}
756 
757 	tx_ring->next_tx = (tx_ring->next_tx + 1) % PRESTERA_SDMA_TX_DESC_PER_Q;
758 	prestera_sdma_tx_desc_xmit(buf->desc);
759 	buf->is_used = true;
760 
761 	prestera_sdma_tx_start(sdma);
762 
763 	goto tx_done;
764 
765 drop_skb_unmap:
766 	prestera_sdma_tx_buf_unmap(sdma, buf);
767 drop_skb:
768 	dev_consume_skb_any(skb);
769 drop_skb_nofree:
770 	dev->stats.tx_dropped++;
771 tx_done:
772 	spin_unlock(&sdma->tx_lock);
773 	return NETDEV_TX_OK;
774 }
775 
776 int prestera_rxtx_switch_init(struct prestera_switch *sw)
777 {
778 	struct prestera_rxtx *rxtx;
779 
780 	rxtx = kzalloc(sizeof(*rxtx), GFP_KERNEL);
781 	if (!rxtx)
782 		return -ENOMEM;
783 
784 	sw->rxtx = rxtx;
785 
786 	return prestera_sdma_switch_init(sw);
787 }
788 
789 void prestera_rxtx_switch_fini(struct prestera_switch *sw)
790 {
791 	prestera_sdma_switch_fini(sw);
792 	kfree(sw->rxtx);
793 }
794 
795 int prestera_rxtx_port_init(struct prestera_port *port)
796 {
797 	port->dev->needed_headroom = PRESTERA_DSA_HLEN;
798 	return 0;
799 }
800 
801 netdev_tx_t prestera_rxtx_xmit(struct prestera_port *port, struct sk_buff *skb)
802 {
803 	struct prestera_dsa dsa;
804 
805 	dsa.hw_dev_num = port->dev_id;
806 	dsa.port_num = port->hw_id;
807 
808 	if (skb_cow_head(skb, PRESTERA_DSA_HLEN) < 0)
809 		return NET_XMIT_DROP;
810 
811 	skb_push(skb, PRESTERA_DSA_HLEN);
812 	memmove(skb->data, skb->data + PRESTERA_DSA_HLEN, 2 * ETH_ALEN);
813 
814 	if (prestera_dsa_build(&dsa, skb->data + 2 * ETH_ALEN) != 0)
815 		return NET_XMIT_DROP;
816 
817 	return prestera_sdma_xmit(&port->sw->rxtx->sdma, skb);
818 }
819