xref: /openbmc/linux/drivers/net/ethernet/amd/xgbe/xgbe-desc.c (revision 63c43812ee99efe7903955bae8cd928e9582477a)
1 /*
2  * AMD 10Gb Ethernet driver
3  *
4  * This file is available to you under your choice of the following two
5  * licenses:
6  *
7  * License 1: GPLv2
8  *
9  * Copyright (c) 2014 Advanced Micro Devices, Inc.
10  *
11  * This file is free software; you may copy, redistribute and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation, either version 2 of the License, or (at
14  * your option) any later version.
15  *
16  * This file is distributed in the hope that it will be useful, but
17  * WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19  * General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
23  *
24  * This file incorporates work covered by the following copyright and
25  * permission notice:
26  *     The Synopsys DWC ETHER XGMAC Software Driver and documentation
27  *     (hereinafter "Software") is an unsupported proprietary work of Synopsys,
28  *     Inc. unless otherwise expressly agreed to in writing between Synopsys
29  *     and you.
30  *
31  *     The Software IS NOT an item of Licensed Software or Licensed Product
32  *     under any End User Software License Agreement or Agreement for Licensed
33  *     Product with Synopsys or any supplement thereto.  Permission is hereby
34  *     granted, free of charge, to any person obtaining a copy of this software
35  *     annotated with this license and the Software, to deal in the Software
36  *     without restriction, including without limitation the rights to use,
37  *     copy, modify, merge, publish, distribute, sublicense, and/or sell copies
38  *     of the Software, and to permit persons to whom the Software is furnished
39  *     to do so, subject to the following conditions:
40  *
41  *     The above copyright notice and this permission notice shall be included
42  *     in all copies or substantial portions of the Software.
43  *
44  *     THIS SOFTWARE IS BEING DISTRIBUTED BY SYNOPSYS SOLELY ON AN "AS IS"
45  *     BASIS AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
46  *     TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
47  *     PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. IN NO EVENT SHALL SYNOPSYS
48  *     BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
49  *     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
50  *     SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
51  *     INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
52  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
53  *     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
54  *     THE POSSIBILITY OF SUCH DAMAGE.
55  *
56  *
57  * License 2: Modified BSD
58  *
59  * Copyright (c) 2014 Advanced Micro Devices, Inc.
60  * All rights reserved.
61  *
62  * Redistribution and use in source and binary forms, with or without
63  * modification, are permitted provided that the following conditions are met:
64  *     * Redistributions of source code must retain the above copyright
65  *       notice, this list of conditions and the following disclaimer.
66  *     * Redistributions in binary form must reproduce the above copyright
67  *       notice, this list of conditions and the following disclaimer in the
68  *       documentation and/or other materials provided with the distribution.
69  *     * Neither the name of Advanced Micro Devices, Inc. nor the
70  *       names of its contributors may be used to endorse or promote products
71  *       derived from this software without specific prior written permission.
72  *
73  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
74  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
75  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
76  * ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
77  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
78  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
79  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
80  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
81  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
82  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
83  *
84  * This file incorporates work covered by the following copyright and
85  * permission notice:
86  *     The Synopsys DWC ETHER XGMAC Software Driver and documentation
87  *     (hereinafter "Software") is an unsupported proprietary work of Synopsys,
88  *     Inc. unless otherwise expressly agreed to in writing between Synopsys
89  *     and you.
90  *
91  *     The Software IS NOT an item of Licensed Software or Licensed Product
92  *     under any End User Software License Agreement or Agreement for Licensed
93  *     Product with Synopsys or any supplement thereto.  Permission is hereby
94  *     granted, free of charge, to any person obtaining a copy of this software
95  *     annotated with this license and the Software, to deal in the Software
96  *     without restriction, including without limitation the rights to use,
97  *     copy, modify, merge, publish, distribute, sublicense, and/or sell copies
98  *     of the Software, and to permit persons to whom the Software is furnished
99  *     to do so, subject to the following conditions:
100  *
101  *     The above copyright notice and this permission notice shall be included
102  *     in all copies or substantial portions of the Software.
103  *
104  *     THIS SOFTWARE IS BEING DISTRIBUTED BY SYNOPSYS SOLELY ON AN "AS IS"
105  *     BASIS AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
106  *     TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
107  *     PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. IN NO EVENT SHALL SYNOPSYS
108  *     BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
109  *     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
110  *     SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
111  *     INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
112  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
113  *     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
114  *     THE POSSIBILITY OF SUCH DAMAGE.
115  */
116 
117 #include "xgbe.h"
118 #include "xgbe-common.h"
119 
120 static void xgbe_unmap_rdata(struct xgbe_prv_data *, struct xgbe_ring_data *);
121 
122 static void xgbe_free_ring(struct xgbe_prv_data *pdata,
123 			   struct xgbe_ring *ring)
124 {
125 	struct xgbe_ring_data *rdata;
126 	unsigned int i;
127 
128 	if (!ring)
129 		return;
130 
131 	if (ring->rdata) {
132 		for (i = 0; i < ring->rdesc_count; i++) {
133 			rdata = XGBE_GET_DESC_DATA(ring, i);
134 			xgbe_unmap_rdata(pdata, rdata);
135 		}
136 
137 		kfree(ring->rdata);
138 		ring->rdata = NULL;
139 	}
140 
141 	if (ring->rx_hdr_pa.pages) {
142 		dma_unmap_page(pdata->dev, ring->rx_hdr_pa.pages_dma,
143 			       ring->rx_hdr_pa.pages_len, DMA_FROM_DEVICE);
144 		put_page(ring->rx_hdr_pa.pages);
145 
146 		ring->rx_hdr_pa.pages = NULL;
147 		ring->rx_hdr_pa.pages_len = 0;
148 		ring->rx_hdr_pa.pages_offset = 0;
149 		ring->rx_hdr_pa.pages_dma = 0;
150 	}
151 
152 	if (ring->rx_buf_pa.pages) {
153 		dma_unmap_page(pdata->dev, ring->rx_buf_pa.pages_dma,
154 			       ring->rx_buf_pa.pages_len, DMA_FROM_DEVICE);
155 		put_page(ring->rx_buf_pa.pages);
156 
157 		ring->rx_buf_pa.pages = NULL;
158 		ring->rx_buf_pa.pages_len = 0;
159 		ring->rx_buf_pa.pages_offset = 0;
160 		ring->rx_buf_pa.pages_dma = 0;
161 	}
162 
163 	if (ring->rdesc) {
164 		dma_free_coherent(pdata->dev,
165 				  (sizeof(struct xgbe_ring_desc) *
166 				   ring->rdesc_count),
167 				  ring->rdesc, ring->rdesc_dma);
168 		ring->rdesc = NULL;
169 	}
170 }
171 
172 static void xgbe_free_ring_resources(struct xgbe_prv_data *pdata)
173 {
174 	struct xgbe_channel *channel;
175 	unsigned int i;
176 
177 	DBGPR("-->xgbe_free_ring_resources\n");
178 
179 	channel = pdata->channel;
180 	for (i = 0; i < pdata->channel_count; i++, channel++) {
181 		xgbe_free_ring(pdata, channel->tx_ring);
182 		xgbe_free_ring(pdata, channel->rx_ring);
183 	}
184 
185 	DBGPR("<--xgbe_free_ring_resources\n");
186 }
187 
188 static int xgbe_init_ring(struct xgbe_prv_data *pdata,
189 			  struct xgbe_ring *ring, unsigned int rdesc_count)
190 {
191 	DBGPR("-->xgbe_init_ring\n");
192 
193 	if (!ring)
194 		return 0;
195 
196 	/* Descriptors */
197 	ring->rdesc_count = rdesc_count;
198 	ring->rdesc = dma_alloc_coherent(pdata->dev,
199 					 (sizeof(struct xgbe_ring_desc) *
200 					  rdesc_count), &ring->rdesc_dma,
201 					 GFP_KERNEL);
202 	if (!ring->rdesc)
203 		return -ENOMEM;
204 
205 	/* Descriptor information */
206 	ring->rdata = kcalloc(rdesc_count, sizeof(struct xgbe_ring_data),
207 			      GFP_KERNEL);
208 	if (!ring->rdata)
209 		return -ENOMEM;
210 
211 	DBGPR("    rdesc=0x%p, rdesc_dma=0x%llx, rdata=0x%p\n",
212 	      ring->rdesc, ring->rdesc_dma, ring->rdata);
213 
214 	DBGPR("<--xgbe_init_ring\n");
215 
216 	return 0;
217 }
218 
219 static int xgbe_alloc_ring_resources(struct xgbe_prv_data *pdata)
220 {
221 	struct xgbe_channel *channel;
222 	unsigned int i;
223 	int ret;
224 
225 	DBGPR("-->xgbe_alloc_ring_resources\n");
226 
227 	channel = pdata->channel;
228 	for (i = 0; i < pdata->channel_count; i++, channel++) {
229 		DBGPR("  %s - tx_ring:\n", channel->name);
230 		ret = xgbe_init_ring(pdata, channel->tx_ring,
231 				     pdata->tx_desc_count);
232 		if (ret) {
233 			netdev_alert(pdata->netdev,
234 				     "error initializing Tx ring\n");
235 			goto err_ring;
236 		}
237 
238 		DBGPR("  %s - rx_ring:\n", channel->name);
239 		ret = xgbe_init_ring(pdata, channel->rx_ring,
240 				     pdata->rx_desc_count);
241 		if (ret) {
242 			netdev_alert(pdata->netdev,
243 				     "error initializing Tx ring\n");
244 			goto err_ring;
245 		}
246 	}
247 
248 	DBGPR("<--xgbe_alloc_ring_resources\n");
249 
250 	return 0;
251 
252 err_ring:
253 	xgbe_free_ring_resources(pdata);
254 
255 	return ret;
256 }
257 
258 static int xgbe_alloc_pages(struct xgbe_prv_data *pdata,
259 			    struct xgbe_page_alloc *pa, gfp_t gfp, int order)
260 {
261 	struct page *pages = NULL;
262 	dma_addr_t pages_dma;
263 	int ret;
264 
265 	/* Try to obtain pages, decreasing order if necessary */
266 	gfp |= __GFP_COLD | __GFP_COMP;
267 	while (order >= 0) {
268 		pages = alloc_pages(gfp, order);
269 		if (pages)
270 			break;
271 
272 		order--;
273 	}
274 	if (!pages)
275 		return -ENOMEM;
276 
277 	/* Map the pages */
278 	pages_dma = dma_map_page(pdata->dev, pages, 0,
279 				 PAGE_SIZE << order, DMA_FROM_DEVICE);
280 	ret = dma_mapping_error(pdata->dev, pages_dma);
281 	if (ret) {
282 		put_page(pages);
283 		return ret;
284 	}
285 
286 	pa->pages = pages;
287 	pa->pages_len = PAGE_SIZE << order;
288 	pa->pages_offset = 0;
289 	pa->pages_dma = pages_dma;
290 
291 	return 0;
292 }
293 
294 static void xgbe_set_buffer_data(struct xgbe_buffer_data *bd,
295 				 struct xgbe_page_alloc *pa,
296 				 unsigned int len)
297 {
298 	get_page(pa->pages);
299 	bd->pa = *pa;
300 
301 	bd->dma = pa->pages_dma + pa->pages_offset;
302 	bd->dma_len = len;
303 
304 	pa->pages_offset += len;
305 	if ((pa->pages_offset + len) > pa->pages_len) {
306 		/* This data descriptor is responsible for unmapping page(s) */
307 		bd->pa_unmap = *pa;
308 
309 		/* Get a new allocation next time */
310 		pa->pages = NULL;
311 		pa->pages_len = 0;
312 		pa->pages_offset = 0;
313 		pa->pages_dma = 0;
314 	}
315 }
316 
317 static int xgbe_map_rx_buffer(struct xgbe_prv_data *pdata,
318 			      struct xgbe_ring *ring,
319 			      struct xgbe_ring_data *rdata)
320 {
321 	int order, ret;
322 
323 	if (!ring->rx_hdr_pa.pages) {
324 		ret = xgbe_alloc_pages(pdata, &ring->rx_hdr_pa, GFP_ATOMIC, 0);
325 		if (ret)
326 			return ret;
327 	}
328 
329 	if (!ring->rx_buf_pa.pages) {
330 		order = max_t(int, PAGE_ALLOC_COSTLY_ORDER - 1, 0);
331 		ret = xgbe_alloc_pages(pdata, &ring->rx_buf_pa, GFP_ATOMIC,
332 				       order);
333 		if (ret)
334 			return ret;
335 	}
336 
337 	/* Set up the header page info */
338 	xgbe_set_buffer_data(&rdata->rx.hdr, &ring->rx_hdr_pa,
339 			     XGBE_SKB_ALLOC_SIZE);
340 
341 	/* Set up the buffer page info */
342 	xgbe_set_buffer_data(&rdata->rx.buf, &ring->rx_buf_pa,
343 			     pdata->rx_buf_size);
344 
345 	return 0;
346 }
347 
348 static void xgbe_wrapper_tx_descriptor_init(struct xgbe_prv_data *pdata)
349 {
350 	struct xgbe_hw_if *hw_if = &pdata->hw_if;
351 	struct xgbe_channel *channel;
352 	struct xgbe_ring *ring;
353 	struct xgbe_ring_data *rdata;
354 	struct xgbe_ring_desc *rdesc;
355 	dma_addr_t rdesc_dma;
356 	unsigned int i, j;
357 
358 	DBGPR("-->xgbe_wrapper_tx_descriptor_init\n");
359 
360 	channel = pdata->channel;
361 	for (i = 0; i < pdata->channel_count; i++, channel++) {
362 		ring = channel->tx_ring;
363 		if (!ring)
364 			break;
365 
366 		rdesc = ring->rdesc;
367 		rdesc_dma = ring->rdesc_dma;
368 
369 		for (j = 0; j < ring->rdesc_count; j++) {
370 			rdata = XGBE_GET_DESC_DATA(ring, j);
371 
372 			rdata->rdesc = rdesc;
373 			rdata->rdesc_dma = rdesc_dma;
374 
375 			rdesc++;
376 			rdesc_dma += sizeof(struct xgbe_ring_desc);
377 		}
378 
379 		ring->cur = 0;
380 		ring->dirty = 0;
381 		memset(&ring->tx, 0, sizeof(ring->tx));
382 
383 		hw_if->tx_desc_init(channel);
384 	}
385 
386 	DBGPR("<--xgbe_wrapper_tx_descriptor_init\n");
387 }
388 
389 static void xgbe_wrapper_rx_descriptor_init(struct xgbe_prv_data *pdata)
390 {
391 	struct xgbe_hw_if *hw_if = &pdata->hw_if;
392 	struct xgbe_channel *channel;
393 	struct xgbe_ring *ring;
394 	struct xgbe_ring_desc *rdesc;
395 	struct xgbe_ring_data *rdata;
396 	dma_addr_t rdesc_dma;
397 	unsigned int i, j;
398 
399 	DBGPR("-->xgbe_wrapper_rx_descriptor_init\n");
400 
401 	channel = pdata->channel;
402 	for (i = 0; i < pdata->channel_count; i++, channel++) {
403 		ring = channel->rx_ring;
404 		if (!ring)
405 			break;
406 
407 		rdesc = ring->rdesc;
408 		rdesc_dma = ring->rdesc_dma;
409 
410 		for (j = 0; j < ring->rdesc_count; j++) {
411 			rdata = XGBE_GET_DESC_DATA(ring, j);
412 
413 			rdata->rdesc = rdesc;
414 			rdata->rdesc_dma = rdesc_dma;
415 
416 			if (xgbe_map_rx_buffer(pdata, ring, rdata))
417 				break;
418 
419 			rdesc++;
420 			rdesc_dma += sizeof(struct xgbe_ring_desc);
421 		}
422 
423 		ring->cur = 0;
424 		ring->dirty = 0;
425 
426 		hw_if->rx_desc_init(channel);
427 	}
428 
429 	DBGPR("<--xgbe_wrapper_rx_descriptor_init\n");
430 }
431 
432 static void xgbe_unmap_rdata(struct xgbe_prv_data *pdata,
433 			     struct xgbe_ring_data *rdata)
434 {
435 	if (rdata->skb_dma) {
436 		if (rdata->mapped_as_page) {
437 			dma_unmap_page(pdata->dev, rdata->skb_dma,
438 				       rdata->skb_dma_len, DMA_TO_DEVICE);
439 		} else {
440 			dma_unmap_single(pdata->dev, rdata->skb_dma,
441 					 rdata->skb_dma_len, DMA_TO_DEVICE);
442 		}
443 		rdata->skb_dma = 0;
444 		rdata->skb_dma_len = 0;
445 	}
446 
447 	if (rdata->skb) {
448 		dev_kfree_skb_any(rdata->skb);
449 		rdata->skb = NULL;
450 	}
451 
452 	if (rdata->rx.hdr.pa.pages)
453 		put_page(rdata->rx.hdr.pa.pages);
454 
455 	if (rdata->rx.hdr.pa_unmap.pages) {
456 		dma_unmap_page(pdata->dev, rdata->rx.hdr.pa_unmap.pages_dma,
457 			       rdata->rx.hdr.pa_unmap.pages_len,
458 			       DMA_FROM_DEVICE);
459 		put_page(rdata->rx.hdr.pa_unmap.pages);
460 	}
461 
462 	if (rdata->rx.buf.pa.pages)
463 		put_page(rdata->rx.buf.pa.pages);
464 
465 	if (rdata->rx.buf.pa_unmap.pages) {
466 		dma_unmap_page(pdata->dev, rdata->rx.buf.pa_unmap.pages_dma,
467 			       rdata->rx.buf.pa_unmap.pages_len,
468 			       DMA_FROM_DEVICE);
469 		put_page(rdata->rx.buf.pa_unmap.pages);
470 	}
471 
472 	memset(&rdata->tx, 0, sizeof(rdata->tx));
473 	memset(&rdata->rx, 0, sizeof(rdata->rx));
474 
475 	rdata->mapped_as_page = 0;
476 
477 	if (rdata->state_saved) {
478 		rdata->state_saved = 0;
479 		rdata->state.incomplete = 0;
480 		rdata->state.context_next = 0;
481 		rdata->state.skb = NULL;
482 		rdata->state.len = 0;
483 		rdata->state.error = 0;
484 	}
485 }
486 
487 static int xgbe_map_tx_skb(struct xgbe_channel *channel, struct sk_buff *skb)
488 {
489 	struct xgbe_prv_data *pdata = channel->pdata;
490 	struct xgbe_ring *ring = channel->tx_ring;
491 	struct xgbe_ring_data *rdata;
492 	struct xgbe_packet_data *packet;
493 	struct skb_frag_struct *frag;
494 	dma_addr_t skb_dma;
495 	unsigned int start_index, cur_index;
496 	unsigned int offset, tso, vlan, datalen, len;
497 	unsigned int i;
498 
499 	DBGPR("-->xgbe_map_tx_skb: cur = %d\n", ring->cur);
500 
501 	offset = 0;
502 	start_index = ring->cur;
503 	cur_index = ring->cur;
504 
505 	packet = &ring->packet_data;
506 	packet->rdesc_count = 0;
507 	packet->length = 0;
508 
509 	tso = XGMAC_GET_BITS(packet->attributes, TX_PACKET_ATTRIBUTES,
510 			     TSO_ENABLE);
511 	vlan = XGMAC_GET_BITS(packet->attributes, TX_PACKET_ATTRIBUTES,
512 			      VLAN_CTAG);
513 
514 	/* Save space for a context descriptor if needed */
515 	if ((tso && (packet->mss != ring->tx.cur_mss)) ||
516 	    (vlan && (packet->vlan_ctag != ring->tx.cur_vlan_ctag)))
517 		cur_index++;
518 	rdata = XGBE_GET_DESC_DATA(ring, cur_index);
519 
520 	if (tso) {
521 		DBGPR("  TSO packet\n");
522 
523 		/* Map the TSO header */
524 		skb_dma = dma_map_single(pdata->dev, skb->data,
525 					 packet->header_len, DMA_TO_DEVICE);
526 		if (dma_mapping_error(pdata->dev, skb_dma)) {
527 			netdev_alert(pdata->netdev, "dma_map_single failed\n");
528 			goto err_out;
529 		}
530 		rdata->skb_dma = skb_dma;
531 		rdata->skb_dma_len = packet->header_len;
532 
533 		offset = packet->header_len;
534 
535 		packet->length += packet->header_len;
536 
537 		cur_index++;
538 		rdata = XGBE_GET_DESC_DATA(ring, cur_index);
539 	}
540 
541 	/* Map the (remainder of the) packet */
542 	for (datalen = skb_headlen(skb) - offset; datalen; ) {
543 		len = min_t(unsigned int, datalen, XGBE_TX_MAX_BUF_SIZE);
544 
545 		skb_dma = dma_map_single(pdata->dev, skb->data + offset, len,
546 					 DMA_TO_DEVICE);
547 		if (dma_mapping_error(pdata->dev, skb_dma)) {
548 			netdev_alert(pdata->netdev, "dma_map_single failed\n");
549 			goto err_out;
550 		}
551 		rdata->skb_dma = skb_dma;
552 		rdata->skb_dma_len = len;
553 		DBGPR("  skb data: index=%u, dma=0x%llx, len=%u\n",
554 		      cur_index, skb_dma, len);
555 
556 		datalen -= len;
557 		offset += len;
558 
559 		packet->length += len;
560 
561 		cur_index++;
562 		rdata = XGBE_GET_DESC_DATA(ring, cur_index);
563 	}
564 
565 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
566 		DBGPR("  mapping frag %u\n", i);
567 
568 		frag = &skb_shinfo(skb)->frags[i];
569 		offset = 0;
570 
571 		for (datalen = skb_frag_size(frag); datalen; ) {
572 			len = min_t(unsigned int, datalen,
573 				    XGBE_TX_MAX_BUF_SIZE);
574 
575 			skb_dma = skb_frag_dma_map(pdata->dev, frag, offset,
576 						   len, DMA_TO_DEVICE);
577 			if (dma_mapping_error(pdata->dev, skb_dma)) {
578 				netdev_alert(pdata->netdev,
579 					     "skb_frag_dma_map failed\n");
580 				goto err_out;
581 			}
582 			rdata->skb_dma = skb_dma;
583 			rdata->skb_dma_len = len;
584 			rdata->mapped_as_page = 1;
585 			DBGPR("  skb data: index=%u, dma=0x%llx, len=%u\n",
586 			      cur_index, skb_dma, len);
587 
588 			datalen -= len;
589 			offset += len;
590 
591 			packet->length += len;
592 
593 			cur_index++;
594 			rdata = XGBE_GET_DESC_DATA(ring, cur_index);
595 		}
596 	}
597 
598 	/* Save the skb address in the last entry. We always have some data
599 	 * that has been mapped so rdata is always advanced past the last
600 	 * piece of mapped data - use the entry pointed to by cur_index - 1.
601 	 */
602 	rdata = XGBE_GET_DESC_DATA(ring, cur_index - 1);
603 	rdata->skb = skb;
604 
605 	/* Save the number of descriptor entries used */
606 	packet->rdesc_count = cur_index - start_index;
607 
608 	DBGPR("<--xgbe_map_tx_skb: count=%u\n", packet->rdesc_count);
609 
610 	return packet->rdesc_count;
611 
612 err_out:
613 	while (start_index < cur_index) {
614 		rdata = XGBE_GET_DESC_DATA(ring, start_index++);
615 		xgbe_unmap_rdata(pdata, rdata);
616 	}
617 
618 	DBGPR("<--xgbe_map_tx_skb: count=0\n");
619 
620 	return 0;
621 }
622 
623 void xgbe_init_function_ptrs_desc(struct xgbe_desc_if *desc_if)
624 {
625 	DBGPR("-->xgbe_init_function_ptrs_desc\n");
626 
627 	desc_if->alloc_ring_resources = xgbe_alloc_ring_resources;
628 	desc_if->free_ring_resources = xgbe_free_ring_resources;
629 	desc_if->map_tx_skb = xgbe_map_tx_skb;
630 	desc_if->map_rx_buffer = xgbe_map_rx_buffer;
631 	desc_if->unmap_rdata = xgbe_unmap_rdata;
632 	desc_if->wrapper_tx_desc_init = xgbe_wrapper_tx_descriptor_init;
633 	desc_if->wrapper_rx_desc_init = xgbe_wrapper_rx_descriptor_init;
634 
635 	DBGPR("<--xgbe_init_function_ptrs_desc\n");
636 }
637