1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright(c) 2013 - 2018 Intel Corporation. */
3 
4 #ifndef _I40E_TXRX_H_
5 #define _I40E_TXRX_H_
6 
7 #include <net/xdp.h>
8 
9 /* Interrupt Throttling and Rate Limiting Goodies */
10 #define I40E_DEFAULT_IRQ_WORK      256
11 
12 /* The datasheet for the X710 and XL710 indicate that the maximum value for
13  * the ITR is 8160usec which is then called out as 0xFF0 with a 2usec
14  * resolution. 8160 is 0x1FE0 when written out in hex. So instead of storing
15  * the register value which is divided by 2 lets use the actual values and
16  * avoid an excessive amount of translation.
17  */
18 #define I40E_ITR_DYNAMIC	0x8000	/* use top bit as a flag */
19 #define I40E_ITR_MASK		0x1FFE	/* mask for ITR register value */
20 #define I40E_MIN_ITR		     2	/* reg uses 2 usec resolution */
21 #define I40E_ITR_20K		    50
22 #define I40E_ITR_8K		   122
23 #define I40E_MAX_ITR		  8160	/* maximum value as per datasheet */
24 #define ITR_TO_REG(setting) ((setting) & ~I40E_ITR_DYNAMIC)
25 #define ITR_REG_ALIGN(setting) __ALIGN_MASK(setting, ~I40E_ITR_MASK)
26 #define ITR_IS_DYNAMIC(setting) (!!((setting) & I40E_ITR_DYNAMIC))
27 
28 #define I40E_ITR_RX_DEF		(I40E_ITR_20K | I40E_ITR_DYNAMIC)
29 #define I40E_ITR_TX_DEF		(I40E_ITR_20K | I40E_ITR_DYNAMIC)
30 
31 /* 0x40 is the enable bit for interrupt rate limiting, and must be set if
32  * the value of the rate limit is non-zero
33  */
34 #define INTRL_ENA                  BIT(6)
35 #define I40E_MAX_INTRL             0x3B    /* reg uses 4 usec resolution */
36 #define INTRL_REG_TO_USEC(intrl) ((intrl & ~INTRL_ENA) << 2)
37 
38 /**
39  * i40e_intrl_usec_to_reg - convert interrupt rate limit to register
40  * @intrl: interrupt rate limit to convert
41  *
42  * This function converts a decimal interrupt rate limit to the appropriate
43  * register format expected by the firmware when setting interrupt rate limit.
44  */
45 static inline u16 i40e_intrl_usec_to_reg(int intrl)
46 {
47 	if (intrl >> 2)
48 		return ((intrl >> 2) | INTRL_ENA);
49 	else
50 		return 0;
51 }
52 
53 #define I40E_QUEUE_END_OF_LIST 0x7FF
54 
55 /* this enum matches hardware bits and is meant to be used by DYN_CTLN
56  * registers and QINT registers or more generally anywhere in the manual
57  * mentioning ITR_INDX, ITR_NONE cannot be used as an index 'n' into any
58  * register but instead is a special value meaning "don't update" ITR0/1/2.
59  */
60 enum i40e_dyn_idx_t {
61 	I40E_IDX_ITR0 = 0,
62 	I40E_IDX_ITR1 = 1,
63 	I40E_IDX_ITR2 = 2,
64 	I40E_ITR_NONE = 3	/* ITR_NONE must not be used as an index */
65 };
66 
67 /* these are indexes into ITRN registers */
68 #define I40E_RX_ITR    I40E_IDX_ITR0
69 #define I40E_TX_ITR    I40E_IDX_ITR1
70 
71 /* Supported RSS offloads */
72 #define I40E_DEFAULT_RSS_HENA ( \
73 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV4_UDP) | \
74 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV4_SCTP) | \
75 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV4_TCP) | \
76 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV4_OTHER) | \
77 	BIT_ULL(I40E_FILTER_PCTYPE_FRAG_IPV4) | \
78 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV6_UDP) | \
79 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV6_TCP) | \
80 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV6_SCTP) | \
81 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV6_OTHER) | \
82 	BIT_ULL(I40E_FILTER_PCTYPE_FRAG_IPV6) | \
83 	BIT_ULL(I40E_FILTER_PCTYPE_L2_PAYLOAD))
84 
85 #define I40E_DEFAULT_RSS_HENA_EXPANDED (I40E_DEFAULT_RSS_HENA | \
86 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV4_TCP_SYN_NO_ACK) | \
87 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_UNICAST_IPV4_UDP) | \
88 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_MULTICAST_IPV4_UDP) | \
89 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_IPV6_TCP_SYN_NO_ACK) | \
90 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_UNICAST_IPV6_UDP) | \
91 	BIT_ULL(I40E_FILTER_PCTYPE_NONF_MULTICAST_IPV6_UDP))
92 
93 #define i40e_pf_get_default_rss_hena(pf) \
94 	(((pf)->hw_features & I40E_HW_MULTIPLE_TCP_UDP_RSS_PCTYPE) ? \
95 	  I40E_DEFAULT_RSS_HENA_EXPANDED : I40E_DEFAULT_RSS_HENA)
96 
97 /* Supported Rx Buffer Sizes (a multiple of 128) */
98 #define I40E_RXBUFFER_256   256
99 #define I40E_RXBUFFER_1536  1536  /* 128B aligned standard Ethernet frame */
100 #define I40E_RXBUFFER_2048  2048
101 #define I40E_RXBUFFER_3072  3072  /* Used for large frames w/ padding */
102 #define I40E_MAX_RXBUFFER   9728  /* largest size for single descriptor */
103 
104 /* NOTE: netdev_alloc_skb reserves up to 64 bytes, NET_IP_ALIGN means we
105  * reserve 2 more, and skb_shared_info adds an additional 384 bytes more,
106  * this adds up to 512 bytes of extra data meaning the smallest allocation
107  * we could have is 1K.
108  * i.e. RXBUFFER_256 --> 960 byte skb (size-1024 slab)
109  * i.e. RXBUFFER_512 --> 1216 byte skb (size-2048 slab)
110  */
111 #define I40E_RX_HDR_SIZE I40E_RXBUFFER_256
112 #define I40E_PACKET_HDR_PAD (ETH_HLEN + ETH_FCS_LEN + (VLAN_HLEN * 2))
113 #define i40e_rx_desc i40e_16byte_rx_desc
114 
115 #define I40E_RX_DMA_ATTR \
116 	(DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING)
117 
118 /* Attempt to maximize the headroom available for incoming frames.  We
119  * use a 2K buffer for receives and need 1536/1534 to store the data for
120  * the frame.  This leaves us with 512 bytes of room.  From that we need
121  * to deduct the space needed for the shared info and the padding needed
122  * to IP align the frame.
123  *
124  * Note: For cache line sizes 256 or larger this value is going to end
125  *	 up negative.  In these cases we should fall back to the legacy
126  *	 receive path.
127  */
128 #if (PAGE_SIZE < 8192)
129 #define I40E_2K_TOO_SMALL_WITH_PADDING \
130 ((NET_SKB_PAD + I40E_RXBUFFER_1536) > SKB_WITH_OVERHEAD(I40E_RXBUFFER_2048))
131 
132 static inline int i40e_compute_pad(int rx_buf_len)
133 {
134 	int page_size, pad_size;
135 
136 	page_size = ALIGN(rx_buf_len, PAGE_SIZE / 2);
137 	pad_size = SKB_WITH_OVERHEAD(page_size) - rx_buf_len;
138 
139 	return pad_size;
140 }
141 
142 static inline int i40e_skb_pad(void)
143 {
144 	int rx_buf_len;
145 
146 	/* If a 2K buffer cannot handle a standard Ethernet frame then
147 	 * optimize padding for a 3K buffer instead of a 1.5K buffer.
148 	 *
149 	 * For a 3K buffer we need to add enough padding to allow for
150 	 * tailroom due to NET_IP_ALIGN possibly shifting us out of
151 	 * cache-line alignment.
152 	 */
153 	if (I40E_2K_TOO_SMALL_WITH_PADDING)
154 		rx_buf_len = I40E_RXBUFFER_3072 + SKB_DATA_ALIGN(NET_IP_ALIGN);
155 	else
156 		rx_buf_len = I40E_RXBUFFER_1536;
157 
158 	/* if needed make room for NET_IP_ALIGN */
159 	rx_buf_len -= NET_IP_ALIGN;
160 
161 	return i40e_compute_pad(rx_buf_len);
162 }
163 
164 #define I40E_SKB_PAD i40e_skb_pad()
165 #else
166 #define I40E_2K_TOO_SMALL_WITH_PADDING false
167 #define I40E_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
168 #endif
169 
170 /**
171  * i40e_test_staterr - tests bits in Rx descriptor status and error fields
172  * @rx_desc: pointer to receive descriptor (in le64 format)
173  * @stat_err_bits: value to mask
174  *
175  * This function does some fast chicanery in order to return the
176  * value of the mask which is really only used for boolean tests.
177  * The status_error_len doesn't need to be shifted because it begins
178  * at offset zero.
179  */
180 static inline bool i40e_test_staterr(union i40e_rx_desc *rx_desc,
181 				     const u64 stat_err_bits)
182 {
183 	return !!(rx_desc->wb.qword1.status_error_len &
184 		  cpu_to_le64(stat_err_bits));
185 }
186 
187 /* How many Rx Buffers do we bundle into one write to the hardware ? */
188 #define I40E_RX_BUFFER_WRITE	32	/* Must be power of 2 */
189 
190 #define I40E_RX_NEXT_DESC(r, i, n)		\
191 	do {					\
192 		(i)++;				\
193 		if ((i) == (r)->count)		\
194 			i = 0;			\
195 		(n) = I40E_RX_DESC((r), (i));	\
196 	} while (0)
197 
198 
199 #define I40E_MAX_BUFFER_TXD	8
200 #define I40E_MIN_TX_LEN		17
201 
202 /* The size limit for a transmit buffer in a descriptor is (16K - 1).
203  * In order to align with the read requests we will align the value to
204  * the nearest 4K which represents our maximum read request size.
205  */
206 #define I40E_MAX_READ_REQ_SIZE		4096
207 #define I40E_MAX_DATA_PER_TXD		(16 * 1024 - 1)
208 #define I40E_MAX_DATA_PER_TXD_ALIGNED \
209 	(I40E_MAX_DATA_PER_TXD & ~(I40E_MAX_READ_REQ_SIZE - 1))
210 
211 /**
212  * i40e_txd_use_count  - estimate the number of descriptors needed for Tx
213  * @size: transmit request size in bytes
214  *
215  * Due to hardware alignment restrictions (4K alignment), we need to
216  * assume that we can have no more than 12K of data per descriptor, even
217  * though each descriptor can take up to 16K - 1 bytes of aligned memory.
218  * Thus, we need to divide by 12K. But division is slow! Instead,
219  * we decompose the operation into shifts and one relatively cheap
220  * multiply operation.
221  *
222  * To divide by 12K, we first divide by 4K, then divide by 3:
223  *     To divide by 4K, shift right by 12 bits
224  *     To divide by 3, multiply by 85, then divide by 256
225  *     (Divide by 256 is done by shifting right by 8 bits)
226  * Finally, we add one to round up. Because 256 isn't an exact multiple of
227  * 3, we'll underestimate near each multiple of 12K. This is actually more
228  * accurate as we have 4K - 1 of wiggle room that we can fit into the last
229  * segment.  For our purposes this is accurate out to 1M which is orders of
230  * magnitude greater than our largest possible GSO size.
231  *
232  * This would then be implemented as:
233  *     return (((size >> 12) * 85) >> 8) + 1;
234  *
235  * Since multiplication and division are commutative, we can reorder
236  * operations into:
237  *     return ((size * 85) >> 20) + 1;
238  */
239 static inline unsigned int i40e_txd_use_count(unsigned int size)
240 {
241 	return ((size * 85) >> 20) + 1;
242 }
243 
244 /* Tx Descriptors needed, worst case */
245 #define DESC_NEEDED (MAX_SKB_FRAGS + 6)
246 
247 #define I40E_TX_FLAGS_HW_VLAN		BIT(1)
248 #define I40E_TX_FLAGS_SW_VLAN		BIT(2)
249 #define I40E_TX_FLAGS_TSO		BIT(3)
250 #define I40E_TX_FLAGS_IPV4		BIT(4)
251 #define I40E_TX_FLAGS_IPV6		BIT(5)
252 #define I40E_TX_FLAGS_TSYN		BIT(8)
253 #define I40E_TX_FLAGS_FD_SB		BIT(9)
254 #define I40E_TX_FLAGS_UDP_TUNNEL	BIT(10)
255 #define I40E_TX_FLAGS_VLAN_MASK		0xffff0000
256 #define I40E_TX_FLAGS_VLAN_PRIO_MASK	0xe0000000
257 #define I40E_TX_FLAGS_VLAN_PRIO_SHIFT	29
258 #define I40E_TX_FLAGS_VLAN_SHIFT	16
259 
260 struct i40e_tx_buffer {
261 	struct i40e_tx_desc *next_to_watch;
262 	union {
263 		struct xdp_frame *xdpf;
264 		struct sk_buff *skb;
265 		void *raw_buf;
266 	};
267 	unsigned int bytecount;
268 	unsigned short gso_segs;
269 
270 	DEFINE_DMA_UNMAP_ADDR(dma);
271 	DEFINE_DMA_UNMAP_LEN(len);
272 	u32 tx_flags;
273 };
274 
275 struct i40e_rx_buffer {
276 	dma_addr_t dma;
277 	struct page *page;
278 	__u32 page_offset;
279 	__u16 pagecnt_bias;
280 	__u32 page_count;
281 };
282 
283 struct i40e_queue_stats {
284 	u64 packets;
285 	u64 bytes;
286 };
287 
288 struct i40e_tx_queue_stats {
289 	u64 restart_queue;
290 	u64 tx_busy;
291 	u64 tx_done_old;
292 	u64 tx_linearize;
293 	u64 tx_force_wb;
294 	u64 tx_stopped;
295 	int prev_pkt_ctr;
296 };
297 
298 struct i40e_rx_queue_stats {
299 	u64 non_eop_descs;
300 	u64 alloc_page_failed;
301 	u64 alloc_buff_failed;
302 	u64 page_reuse_count;
303 	u64 page_alloc_count;
304 	u64 page_waive_count;
305 	u64 page_busy_count;
306 };
307 
308 enum i40e_ring_state_t {
309 	__I40E_TX_FDIR_INIT_DONE,
310 	__I40E_TX_XPS_INIT_DONE,
311 	__I40E_RING_STATE_NBITS /* must be last */
312 };
313 
314 /* some useful defines for virtchannel interface, which
315  * is the only remaining user of header split
316  */
317 #define I40E_RX_DTYPE_HEADER_SPLIT  1
318 #define I40E_RX_SPLIT_L2      0x1
319 #define I40E_RX_SPLIT_IP      0x2
320 #define I40E_RX_SPLIT_TCP_UDP 0x4
321 #define I40E_RX_SPLIT_SCTP    0x8
322 
323 /* struct that defines a descriptor ring, associated with a VSI */
324 struct i40e_ring {
325 	struct i40e_ring *next;		/* pointer to next ring in q_vector */
326 	void *desc;			/* Descriptor ring memory */
327 	struct device *dev;		/* Used for DMA mapping */
328 	struct net_device *netdev;	/* netdev ring maps to */
329 	struct bpf_prog *xdp_prog;
330 	union {
331 		struct i40e_tx_buffer *tx_bi;
332 		struct i40e_rx_buffer *rx_bi;
333 		struct xdp_buff **rx_bi_zc;
334 	};
335 	DECLARE_BITMAP(state, __I40E_RING_STATE_NBITS);
336 	u16 queue_index;		/* Queue number of ring */
337 	u8 dcb_tc;			/* Traffic class of ring */
338 	u8 __iomem *tail;
339 
340 	/* Storing xdp_buff on ring helps in saving the state of partially built
341 	 * packet when i40e_clean_rx_ring_irq() must return before it sees EOP
342 	 * and to resume packet building for this ring in the next call to
343 	 * i40e_clean_rx_ring_irq().
344 	 */
345 	struct xdp_buff xdp;
346 
347 	/* Next descriptor to be processed; next_to_clean is updated only on
348 	 * processing EOP descriptor
349 	 */
350 	u16 next_to_process;
351 	/* high bit set means dynamic, use accessor routines to read/write.
352 	 * hardware only supports 2us resolution for the ITR registers.
353 	 * these values always store the USER setting, and must be converted
354 	 * before programming to a register.
355 	 */
356 	u16 itr_setting;
357 
358 	u16 count;			/* Number of descriptors */
359 	u16 reg_idx;			/* HW register index of the ring */
360 	u16 rx_buf_len;
361 
362 	/* used in interrupt processing */
363 	u16 next_to_use;
364 	u16 next_to_clean;
365 	u16 xdp_tx_active;
366 
367 	u8 atr_sample_rate;
368 	u8 atr_count;
369 
370 	bool ring_active;		/* is ring online or not */
371 	bool arm_wb;		/* do something to arm write back */
372 	u8 packet_stride;
373 
374 	u16 flags;
375 #define I40E_TXR_FLAGS_WB_ON_ITR		BIT(0)
376 #define I40E_RXR_FLAGS_BUILD_SKB_ENABLED	BIT(1)
377 #define I40E_TXR_FLAGS_XDP			BIT(2)
378 
379 	/* stats structs */
380 	struct i40e_queue_stats	stats;
381 	struct u64_stats_sync syncp;
382 	union {
383 		struct i40e_tx_queue_stats tx_stats;
384 		struct i40e_rx_queue_stats rx_stats;
385 	};
386 
387 	unsigned int size;		/* length of descriptor ring in bytes */
388 	dma_addr_t dma;			/* physical address of ring */
389 
390 	struct i40e_vsi *vsi;		/* Backreference to associated VSI */
391 	struct i40e_q_vector *q_vector;	/* Backreference to associated vector */
392 
393 	struct rcu_head rcu;		/* to avoid race on free */
394 	u16 next_to_alloc;
395 
396 	struct i40e_channel *ch;
397 	u16 rx_offset;
398 	struct xdp_rxq_info xdp_rxq;
399 	struct xsk_buff_pool *xsk_pool;
400 } ____cacheline_internodealigned_in_smp;
401 
402 static inline bool ring_uses_build_skb(struct i40e_ring *ring)
403 {
404 	return !!(ring->flags & I40E_RXR_FLAGS_BUILD_SKB_ENABLED);
405 }
406 
407 static inline void set_ring_build_skb_enabled(struct i40e_ring *ring)
408 {
409 	ring->flags |= I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
410 }
411 
412 static inline void clear_ring_build_skb_enabled(struct i40e_ring *ring)
413 {
414 	ring->flags &= ~I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
415 }
416 
417 static inline bool ring_is_xdp(struct i40e_ring *ring)
418 {
419 	return !!(ring->flags & I40E_TXR_FLAGS_XDP);
420 }
421 
422 static inline void set_ring_xdp(struct i40e_ring *ring)
423 {
424 	ring->flags |= I40E_TXR_FLAGS_XDP;
425 }
426 
427 #define I40E_ITR_ADAPTIVE_MIN_INC	0x0002
428 #define I40E_ITR_ADAPTIVE_MIN_USECS	0x0002
429 #define I40E_ITR_ADAPTIVE_MAX_USECS	0x007e
430 #define I40E_ITR_ADAPTIVE_LATENCY	0x8000
431 #define I40E_ITR_ADAPTIVE_BULK		0x0000
432 
433 struct i40e_ring_container {
434 	struct i40e_ring *ring;		/* pointer to linked list of ring(s) */
435 	unsigned long next_update;	/* jiffies value of next update */
436 	unsigned int total_bytes;	/* total bytes processed this int */
437 	unsigned int total_packets;	/* total packets processed this int */
438 	u16 count;
439 	u16 target_itr;			/* target ITR setting for ring(s) */
440 	u16 current_itr;		/* current ITR setting for ring(s) */
441 };
442 
443 /* iterator for handling rings in ring container */
444 #define i40e_for_each_ring(pos, head) \
445 	for (pos = (head).ring; pos != NULL; pos = pos->next)
446 
447 static inline unsigned int i40e_rx_pg_order(struct i40e_ring *ring)
448 {
449 #if (PAGE_SIZE < 8192)
450 	if (ring->rx_buf_len > (PAGE_SIZE / 2))
451 		return 1;
452 #endif
453 	return 0;
454 }
455 
456 #define i40e_rx_pg_size(_ring) (PAGE_SIZE << i40e_rx_pg_order(_ring))
457 
458 bool i40e_alloc_rx_buffers(struct i40e_ring *rxr, u16 cleaned_count);
459 netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev);
460 u16 i40e_lan_select_queue(struct net_device *netdev, struct sk_buff *skb,
461 			  struct net_device *sb_dev);
462 void i40e_clean_tx_ring(struct i40e_ring *tx_ring);
463 void i40e_clean_rx_ring(struct i40e_ring *rx_ring);
464 int i40e_setup_tx_descriptors(struct i40e_ring *tx_ring);
465 int i40e_setup_rx_descriptors(struct i40e_ring *rx_ring);
466 void i40e_free_tx_resources(struct i40e_ring *tx_ring);
467 void i40e_free_rx_resources(struct i40e_ring *rx_ring);
468 int i40e_napi_poll(struct napi_struct *napi, int budget);
469 void i40e_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector);
470 u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw);
471 void i40e_detect_recover_hung(struct i40e_vsi *vsi);
472 int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size);
473 bool __i40e_chk_linearize(struct sk_buff *skb);
474 int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
475 		  u32 flags);
476 bool i40e_is_non_eop(struct i40e_ring *rx_ring,
477 		     union i40e_rx_desc *rx_desc);
478 
479 /**
480  * i40e_get_head - Retrieve head from head writeback
481  * @tx_ring:  tx ring to fetch head of
482  *
483  * Returns value of Tx ring head based on value stored
484  * in head write-back location
485  **/
486 static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
487 {
488 	void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
489 
490 	return le32_to_cpu(*(volatile __le32 *)head);
491 }
492 
493 /**
494  * i40e_xmit_descriptor_count - calculate number of Tx descriptors needed
495  * @skb:     send buffer
496  *
497  * Returns number of data descriptors needed for this skb. Returns 0 to indicate
498  * there is not enough descriptors available in this ring since we need at least
499  * one descriptor.
500  **/
501 static inline int i40e_xmit_descriptor_count(struct sk_buff *skb)
502 {
503 	const skb_frag_t *frag = &skb_shinfo(skb)->frags[0];
504 	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
505 	int count = 0, size = skb_headlen(skb);
506 
507 	for (;;) {
508 		count += i40e_txd_use_count(size);
509 
510 		if (!nr_frags--)
511 			break;
512 
513 		size = skb_frag_size(frag++);
514 	}
515 
516 	return count;
517 }
518 
519 /**
520  * i40e_maybe_stop_tx - 1st level check for Tx stop conditions
521  * @tx_ring: the ring to be checked
522  * @size:    the size buffer we want to assure is available
523  *
524  * Returns 0 if stop is not needed
525  **/
526 static inline int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
527 {
528 	if (likely(I40E_DESC_UNUSED(tx_ring) >= size))
529 		return 0;
530 	return __i40e_maybe_stop_tx(tx_ring, size);
531 }
532 
533 /**
534  * i40e_chk_linearize - Check if there are more than 8 fragments per packet
535  * @skb:      send buffer
536  * @count:    number of buffers used
537  *
538  * Note: Our HW can't scatter-gather more than 8 fragments to build
539  * a packet on the wire and so we need to figure out the cases where we
540  * need to linearize the skb.
541  **/
542 static inline bool i40e_chk_linearize(struct sk_buff *skb, int count)
543 {
544 	/* Both TSO and single send will work if count is less than 8 */
545 	if (likely(count < I40E_MAX_BUFFER_TXD))
546 		return false;
547 
548 	if (skb_is_gso(skb))
549 		return __i40e_chk_linearize(skb);
550 
551 	/* we can support up to 8 data buffers for a single send */
552 	return count != I40E_MAX_BUFFER_TXD;
553 }
554 
555 /**
556  * txring_txq - Find the netdev Tx ring based on the i40e Tx ring
557  * @ring: Tx ring to find the netdev equivalent of
558  **/
559 static inline struct netdev_queue *txring_txq(const struct i40e_ring *ring)
560 {
561 	return netdev_get_tx_queue(ring->netdev, ring->queue_index);
562 }
563 #endif /* _I40E_TXRX_H_ */
564