1 // SPDX-License-Identifier: GPL-2.0-only
2 /****************************************************************************
3  * Driver for Solarflare network controllers and boards
4  * Copyright 2018 Solarflare Communications Inc.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published
8  * by the Free Software Foundation, incorporated herein by reference.
9  */
10 
11 #include "net_driver.h"
12 #include "efx.h"
13 #include "nic_common.h"
14 #include "tx_common.h"
15 
16 static unsigned int efx_tx_cb_page_count(struct efx_tx_queue *tx_queue)
17 {
18 	return DIV_ROUND_UP(tx_queue->ptr_mask + 1,
19 			    PAGE_SIZE >> EFX_TX_CB_ORDER);
20 }
21 
22 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
23 {
24 	struct efx_nic *efx = tx_queue->efx;
25 	unsigned int entries;
26 	int rc;
27 
28 	/* Create the smallest power-of-two aligned ring */
29 	entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE);
30 	EFX_WARN_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
31 	tx_queue->ptr_mask = entries - 1;
32 
33 	netif_dbg(efx, probe, efx->net_dev,
34 		  "creating TX queue %d size %#x mask %#x\n",
35 		  tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask);
36 
37 	/* Allocate software ring */
38 	tx_queue->buffer = kcalloc(entries, sizeof(*tx_queue->buffer),
39 				   GFP_KERNEL);
40 	if (!tx_queue->buffer)
41 		return -ENOMEM;
42 
43 	tx_queue->cb_page = kcalloc(efx_tx_cb_page_count(tx_queue),
44 				    sizeof(tx_queue->cb_page[0]), GFP_KERNEL);
45 	if (!tx_queue->cb_page) {
46 		rc = -ENOMEM;
47 		goto fail1;
48 	}
49 
50 	/* Allocate hardware ring, determine TXQ type */
51 	rc = efx_nic_probe_tx(tx_queue);
52 	if (rc)
53 		goto fail2;
54 
55 	tx_queue->channel->tx_queue_by_type[tx_queue->type] = tx_queue;
56 	return 0;
57 
58 fail2:
59 	kfree(tx_queue->cb_page);
60 	tx_queue->cb_page = NULL;
61 fail1:
62 	kfree(tx_queue->buffer);
63 	tx_queue->buffer = NULL;
64 	return rc;
65 }
66 
67 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
68 {
69 	struct efx_nic *efx = tx_queue->efx;
70 
71 	netif_dbg(efx, drv, efx->net_dev,
72 		  "initialising TX queue %d\n", tx_queue->queue);
73 
74 	tx_queue->insert_count = 0;
75 	tx_queue->notify_count = 0;
76 	tx_queue->write_count = 0;
77 	tx_queue->packet_write_count = 0;
78 	tx_queue->old_write_count = 0;
79 	tx_queue->read_count = 0;
80 	tx_queue->old_read_count = 0;
81 	tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
82 	tx_queue->xmit_pending = false;
83 	tx_queue->timestamping = (efx_ptp_use_mac_tx_timestamps(efx) &&
84 				  tx_queue->channel == efx_ptp_channel(efx));
85 	tx_queue->completed_timestamp_major = 0;
86 	tx_queue->completed_timestamp_minor = 0;
87 
88 	tx_queue->xdp_tx = efx_channel_is_xdp_tx(tx_queue->channel);
89 	tx_queue->tso_version = 0;
90 
91 	/* Set up TX descriptor ring */
92 	efx_nic_init_tx(tx_queue);
93 
94 	tx_queue->initialised = true;
95 }
96 
97 void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
98 {
99 	struct efx_tx_buffer *buffer;
100 
101 	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
102 		  "shutting down TX queue %d\n", tx_queue->queue);
103 
104 	if (!tx_queue->buffer)
105 		return;
106 
107 	/* Free any buffers left in the ring */
108 	while (tx_queue->read_count != tx_queue->write_count) {
109 		unsigned int pkts_compl = 0, bytes_compl = 0;
110 
111 		buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
112 		efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
113 
114 		++tx_queue->read_count;
115 	}
116 	tx_queue->xmit_pending = false;
117 	netdev_tx_reset_queue(tx_queue->core_txq);
118 }
119 
120 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
121 {
122 	int i;
123 
124 	if (!tx_queue->buffer)
125 		return;
126 
127 	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
128 		  "destroying TX queue %d\n", tx_queue->queue);
129 	efx_nic_remove_tx(tx_queue);
130 
131 	if (tx_queue->cb_page) {
132 		for (i = 0; i < efx_tx_cb_page_count(tx_queue); i++)
133 			efx_nic_free_buffer(tx_queue->efx,
134 					    &tx_queue->cb_page[i]);
135 		kfree(tx_queue->cb_page);
136 		tx_queue->cb_page = NULL;
137 	}
138 
139 	kfree(tx_queue->buffer);
140 	tx_queue->buffer = NULL;
141 	tx_queue->channel->tx_queue_by_type[tx_queue->type] = NULL;
142 }
143 
144 void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
145 			struct efx_tx_buffer *buffer,
146 			unsigned int *pkts_compl,
147 			unsigned int *bytes_compl)
148 {
149 	if (buffer->unmap_len) {
150 		struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
151 		dma_addr_t unmap_addr = buffer->dma_addr - buffer->dma_offset;
152 
153 		if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
154 			dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
155 					 DMA_TO_DEVICE);
156 		else
157 			dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
158 				       DMA_TO_DEVICE);
159 		buffer->unmap_len = 0;
160 	}
161 
162 	if (buffer->flags & EFX_TX_BUF_SKB) {
163 		struct sk_buff *skb = (struct sk_buff *)buffer->skb;
164 
165 		EFX_WARN_ON_PARANOID(!pkts_compl || !bytes_compl);
166 		(*pkts_compl)++;
167 		(*bytes_compl) += skb->len;
168 		if (tx_queue->timestamping &&
169 		    (tx_queue->completed_timestamp_major ||
170 		     tx_queue->completed_timestamp_minor)) {
171 			struct skb_shared_hwtstamps hwtstamp;
172 
173 			hwtstamp.hwtstamp =
174 				efx_ptp_nic_to_kernel_time(tx_queue);
175 			skb_tstamp_tx(skb, &hwtstamp);
176 
177 			tx_queue->completed_timestamp_major = 0;
178 			tx_queue->completed_timestamp_minor = 0;
179 		}
180 		dev_consume_skb_any((struct sk_buff *)buffer->skb);
181 		netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
182 			   "TX queue %d transmission id %x complete\n",
183 			   tx_queue->queue, tx_queue->read_count);
184 	} else if (buffer->flags & EFX_TX_BUF_XDP) {
185 		xdp_return_frame_rx_napi(buffer->xdpf);
186 	}
187 
188 	buffer->len = 0;
189 	buffer->flags = 0;
190 }
191 
192 /* Remove packets from the TX queue
193  *
194  * This removes packets from the TX queue, up to and including the
195  * specified index.
196  */
197 static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
198 				unsigned int index,
199 				unsigned int *pkts_compl,
200 				unsigned int *bytes_compl)
201 {
202 	struct efx_nic *efx = tx_queue->efx;
203 	unsigned int stop_index, read_ptr;
204 
205 	stop_index = (index + 1) & tx_queue->ptr_mask;
206 	read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
207 
208 	while (read_ptr != stop_index) {
209 		struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
210 
211 		if (!efx_tx_buffer_in_use(buffer)) {
212 			netif_err(efx, tx_err, efx->net_dev,
213 				  "TX queue %d spurious TX completion id %d\n",
214 				  tx_queue->queue, read_ptr);
215 			efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
216 			return;
217 		}
218 
219 		efx_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
220 
221 		++tx_queue->read_count;
222 		read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
223 	}
224 }
225 
226 void efx_xmit_done_check_empty(struct efx_tx_queue *tx_queue)
227 {
228 	if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
229 		tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
230 		if (tx_queue->read_count == tx_queue->old_write_count) {
231 			/* Ensure that read_count is flushed. */
232 			smp_mb();
233 			tx_queue->empty_read_count =
234 				tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
235 		}
236 	}
237 }
238 
239 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
240 {
241 	unsigned int fill_level, pkts_compl = 0, bytes_compl = 0;
242 	struct efx_nic *efx = tx_queue->efx;
243 
244 	EFX_WARN_ON_ONCE_PARANOID(index > tx_queue->ptr_mask);
245 
246 	efx_dequeue_buffers(tx_queue, index, &pkts_compl, &bytes_compl);
247 	tx_queue->pkts_compl += pkts_compl;
248 	tx_queue->bytes_compl += bytes_compl;
249 
250 	if (pkts_compl > 1)
251 		++tx_queue->merge_events;
252 
253 	/* See if we need to restart the netif queue.  This memory
254 	 * barrier ensures that we write read_count (inside
255 	 * efx_dequeue_buffers()) before reading the queue status.
256 	 */
257 	smp_mb();
258 	if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
259 	    likely(efx->port_enabled) &&
260 	    likely(netif_device_present(efx->net_dev))) {
261 		fill_level = efx_channel_tx_fill_level(tx_queue->channel);
262 		if (fill_level <= efx->txq_wake_thresh)
263 			netif_tx_wake_queue(tx_queue->core_txq);
264 	}
265 
266 	efx_xmit_done_check_empty(tx_queue);
267 }
268 
269 /* Remove buffers put into a tx_queue for the current packet.
270  * None of the buffers must have an skb attached.
271  */
272 void efx_enqueue_unwind(struct efx_tx_queue *tx_queue,
273 			unsigned int insert_count)
274 {
275 	struct efx_tx_buffer *buffer;
276 	unsigned int bytes_compl = 0;
277 	unsigned int pkts_compl = 0;
278 
279 	/* Work backwards until we hit the original insert pointer value */
280 	while (tx_queue->insert_count != insert_count) {
281 		--tx_queue->insert_count;
282 		buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
283 		efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
284 	}
285 }
286 
287 struct efx_tx_buffer *efx_tx_map_chunk(struct efx_tx_queue *tx_queue,
288 				       dma_addr_t dma_addr, size_t len)
289 {
290 	const struct efx_nic_type *nic_type = tx_queue->efx->type;
291 	struct efx_tx_buffer *buffer;
292 	unsigned int dma_len;
293 
294 	/* Map the fragment taking account of NIC-dependent DMA limits. */
295 	do {
296 		buffer = efx_tx_queue_get_insert_buffer(tx_queue);
297 
298 		if (nic_type->tx_limit_len)
299 			dma_len = nic_type->tx_limit_len(tx_queue, dma_addr, len);
300 		else
301 			dma_len = len;
302 
303 		buffer->len = dma_len;
304 		buffer->dma_addr = dma_addr;
305 		buffer->flags = EFX_TX_BUF_CONT;
306 		len -= dma_len;
307 		dma_addr += dma_len;
308 		++tx_queue->insert_count;
309 	} while (len);
310 
311 	return buffer;
312 }
313 
314 int efx_tx_tso_header_length(struct sk_buff *skb)
315 {
316 	size_t header_len;
317 
318 	if (skb->encapsulation)
319 		header_len = skb_inner_transport_header(skb) -
320 				skb->data +
321 				(inner_tcp_hdr(skb)->doff << 2u);
322 	else
323 		header_len = skb_transport_header(skb) - skb->data +
324 				(tcp_hdr(skb)->doff << 2u);
325 	return header_len;
326 }
327 
328 /* Map all data from an SKB for DMA and create descriptors on the queue. */
329 int efx_tx_map_data(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
330 		    unsigned int segment_count)
331 {
332 	struct efx_nic *efx = tx_queue->efx;
333 	struct device *dma_dev = &efx->pci_dev->dev;
334 	unsigned int frag_index, nr_frags;
335 	dma_addr_t dma_addr, unmap_addr;
336 	unsigned short dma_flags;
337 	size_t len, unmap_len;
338 
339 	nr_frags = skb_shinfo(skb)->nr_frags;
340 	frag_index = 0;
341 
342 	/* Map header data. */
343 	len = skb_headlen(skb);
344 	dma_addr = dma_map_single(dma_dev, skb->data, len, DMA_TO_DEVICE);
345 	dma_flags = EFX_TX_BUF_MAP_SINGLE;
346 	unmap_len = len;
347 	unmap_addr = dma_addr;
348 
349 	if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
350 		return -EIO;
351 
352 	if (segment_count) {
353 		/* For TSO we need to put the header in to a separate
354 		 * descriptor. Map this separately if necessary.
355 		 */
356 		size_t header_len = efx_tx_tso_header_length(skb);
357 
358 		if (header_len != len) {
359 			tx_queue->tso_long_headers++;
360 			efx_tx_map_chunk(tx_queue, dma_addr, header_len);
361 			len -= header_len;
362 			dma_addr += header_len;
363 		}
364 	}
365 
366 	/* Add descriptors for each fragment. */
367 	do {
368 		struct efx_tx_buffer *buffer;
369 		skb_frag_t *fragment;
370 
371 		buffer = efx_tx_map_chunk(tx_queue, dma_addr, len);
372 
373 		/* The final descriptor for a fragment is responsible for
374 		 * unmapping the whole fragment.
375 		 */
376 		buffer->flags = EFX_TX_BUF_CONT | dma_flags;
377 		buffer->unmap_len = unmap_len;
378 		buffer->dma_offset = buffer->dma_addr - unmap_addr;
379 
380 		if (frag_index >= nr_frags) {
381 			/* Store SKB details with the final buffer for
382 			 * the completion.
383 			 */
384 			buffer->skb = skb;
385 			buffer->flags = EFX_TX_BUF_SKB | dma_flags;
386 			return 0;
387 		}
388 
389 		/* Move on to the next fragment. */
390 		fragment = &skb_shinfo(skb)->frags[frag_index++];
391 		len = skb_frag_size(fragment);
392 		dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
393 					    DMA_TO_DEVICE);
394 		dma_flags = 0;
395 		unmap_len = len;
396 		unmap_addr = dma_addr;
397 
398 		if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
399 			return -EIO;
400 	} while (1);
401 }
402 
403 unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
404 {
405 	/* Header and payload descriptor for each output segment, plus
406 	 * one for every input fragment boundary within a segment
407 	 */
408 	unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
409 
410 	/* Possibly one more per segment for option descriptors */
411 	if (efx_nic_rev(efx) >= EFX_REV_HUNT_A0)
412 		max_descs += EFX_TSO_MAX_SEGS;
413 
414 	/* Possibly more for PCIe page boundaries within input fragments */
415 	if (PAGE_SIZE > EFX_PAGE_SIZE)
416 		max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
417 				   DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
418 
419 	return max_descs;
420 }
421 
422 /*
423  * Fallback to software TSO.
424  *
425  * This is used if we are unable to send a GSO packet through hardware TSO.
426  * This should only ever happen due to per-queue restrictions - unsupported
427  * packets should first be filtered by the feature flags.
428  *
429  * Returns 0 on success, error code otherwise.
430  */
431 int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
432 {
433 	struct sk_buff *segments, *next;
434 
435 	segments = skb_gso_segment(skb, 0);
436 	if (IS_ERR(segments))
437 		return PTR_ERR(segments);
438 
439 	dev_consume_skb_any(skb);
440 
441 	skb_list_walk_safe(segments, skb, next) {
442 		skb_mark_not_on_list(skb);
443 		efx_enqueue_skb(tx_queue, skb);
444 	}
445 
446 	return 0;
447 }
448