xref: /openbmc/linux/drivers/net/ethernet/google/gve/gve.h (revision bef7a78d)
1 /* SPDX-License-Identifier: (GPL-2.0 OR MIT)
2  * Google virtual Ethernet (gve) driver
3  *
4  * Copyright (C) 2015-2019 Google, Inc.
5  */
6 
7 #ifndef _GVE_H_
8 #define _GVE_H_
9 
10 #include <linux/dma-mapping.h>
11 #include <linux/netdevice.h>
12 #include <linux/pci.h>
13 #include <linux/u64_stats_sync.h>
14 #include "gve_desc.h"
15 
16 #ifndef PCI_VENDOR_ID_GOOGLE
17 #define PCI_VENDOR_ID_GOOGLE	0x1ae0
18 #endif
19 
20 #define PCI_DEV_ID_GVNIC	0x0042
21 
22 #define GVE_REGISTER_BAR	0
23 #define GVE_DOORBELL_BAR	2
24 
25 /* Driver can alloc up to 2 segments for the header and 2 for the payload. */
26 #define GVE_TX_MAX_IOVEC	4
27 /* 1 for management, 1 for rx, 1 for tx */
28 #define GVE_MIN_MSIX 3
29 
30 /* Numbers of gve tx/rx stats in stats report. */
31 #define GVE_TX_STATS_REPORT_NUM	5
32 #define GVE_RX_STATS_REPORT_NUM	2
33 
34 /* Interval to schedule a stats report update, 20000ms. */
35 #define GVE_STATS_REPORT_TIMER_PERIOD	20000
36 
37 /* Numbers of NIC tx/rx stats in stats report. */
38 #define NIC_TX_STATS_REPORT_NUM	0
39 #define NIC_RX_STATS_REPORT_NUM	4
40 
41 #define GVE_DATA_SLOT_ADDR_PAGE_MASK (~(PAGE_SIZE - 1))
42 
43 /* Each slot in the desc ring has a 1:1 mapping to a slot in the data ring */
44 struct gve_rx_desc_queue {
45 	struct gve_rx_desc *desc_ring; /* the descriptor ring */
46 	dma_addr_t bus; /* the bus for the desc_ring */
47 	u8 seqno; /* the next expected seqno for this desc*/
48 };
49 
50 /* The page info for a single slot in the RX data queue */
51 struct gve_rx_slot_page_info {
52 	struct page *page;
53 	void *page_address;
54 	u8 page_offset; /* flipped to second half? */
55 	u8 can_flip;
56 };
57 
58 /* A list of pages registered with the device during setup and used by a queue
59  * as buffers
60  */
61 struct gve_queue_page_list {
62 	u32 id; /* unique id */
63 	u32 num_entries;
64 	struct page **pages; /* list of num_entries pages */
65 	dma_addr_t *page_buses; /* the dma addrs of the pages */
66 };
67 
68 /* Each slot in the data ring has a 1:1 mapping to a slot in the desc ring */
69 struct gve_rx_data_queue {
70 	union gve_rx_data_slot *data_ring; /* read by NIC */
71 	dma_addr_t data_bus; /* dma mapping of the slots */
72 	struct gve_rx_slot_page_info *page_info; /* page info of the buffers */
73 	struct gve_queue_page_list *qpl; /* qpl assigned to this queue */
74 	u8 raw_addressing; /* use raw_addressing? */
75 };
76 
77 struct gve_priv;
78 
79 /* An RX ring that contains a power-of-two sized desc and data ring. */
80 struct gve_rx_ring {
81 	struct gve_priv *gve;
82 	struct gve_rx_desc_queue desc;
83 	struct gve_rx_data_queue data;
84 	u64 rbytes; /* free-running bytes received */
85 	u64 rpackets; /* free-running packets received */
86 	u32 cnt; /* free-running total number of completed packets */
87 	u32 fill_cnt; /* free-running total number of descs and buffs posted */
88 	u32 mask; /* masks the cnt and fill_cnt to the size of the ring */
89 	u32 db_threshold; /* threshold for posting new buffs and descs */
90 	u64 rx_copybreak_pkt; /* free-running count of copybreak packets */
91 	u64 rx_copied_pkt; /* free-running total number of copied packets */
92 	u64 rx_skb_alloc_fail; /* free-running count of skb alloc fails */
93 	u64 rx_buf_alloc_fail; /* free-running count of buffer alloc fails */
94 	u64 rx_desc_err_dropped_pkt; /* free-running count of packets dropped by descriptor error */
95 	u32 q_num; /* queue index */
96 	u32 ntfy_id; /* notification block index */
97 	struct gve_queue_resources *q_resources; /* head and tail pointer idx */
98 	dma_addr_t q_resources_bus; /* dma address for the queue resources */
99 	struct u64_stats_sync statss; /* sync stats for 32bit archs */
100 };
101 
102 /* A TX desc ring entry */
103 union gve_tx_desc {
104 	struct gve_tx_pkt_desc pkt; /* first desc for a packet */
105 	struct gve_tx_seg_desc seg; /* subsequent descs for a packet */
106 };
107 
108 /* Tracks the memory in the fifo occupied by a segment of a packet */
109 struct gve_tx_iovec {
110 	u32 iov_offset; /* offset into this segment */
111 	u32 iov_len; /* length */
112 	u32 iov_padding; /* padding associated with this segment */
113 };
114 
115 struct gve_tx_dma_buf {
116 	DEFINE_DMA_UNMAP_ADDR(dma);
117 	DEFINE_DMA_UNMAP_LEN(len);
118 };
119 
120 /* Tracks the memory in the fifo occupied by the skb. Mapped 1:1 to a desc
121  * ring entry but only used for a pkt_desc not a seg_desc
122  */
123 struct gve_tx_buffer_state {
124 	struct sk_buff *skb; /* skb for this pkt */
125 	union {
126 		struct gve_tx_iovec iov[GVE_TX_MAX_IOVEC]; /* segments of this pkt */
127 		struct gve_tx_dma_buf buf;
128 	};
129 };
130 
131 /* A TX buffer - each queue has one */
132 struct gve_tx_fifo {
133 	void *base; /* address of base of FIFO */
134 	u32 size; /* total size */
135 	atomic_t available; /* how much space is still available */
136 	u32 head; /* offset to write at */
137 	struct gve_queue_page_list *qpl; /* QPL mapped into this FIFO */
138 };
139 
140 /* A TX ring that contains a power-of-two sized desc ring and a FIFO buffer */
141 struct gve_tx_ring {
142 	/* Cacheline 0 -- Accessed & dirtied during transmit */
143 	struct gve_tx_fifo tx_fifo;
144 	u32 req; /* driver tracked head pointer */
145 	u32 done; /* driver tracked tail pointer */
146 
147 	/* Cacheline 1 -- Accessed & dirtied during gve_clean_tx_done */
148 	__be32 last_nic_done ____cacheline_aligned; /* NIC tail pointer */
149 	u64 pkt_done; /* free-running - total packets completed */
150 	u64 bytes_done; /* free-running - total bytes completed */
151 	u64 dropped_pkt; /* free-running - total packets dropped */
152 	u64 dma_mapping_error; /* count of dma mapping errors */
153 
154 	/* Cacheline 2 -- Read-mostly fields */
155 	union gve_tx_desc *desc ____cacheline_aligned;
156 	struct gve_tx_buffer_state *info; /* Maps 1:1 to a desc */
157 	struct netdev_queue *netdev_txq;
158 	struct gve_queue_resources *q_resources; /* head and tail pointer idx */
159 	struct device *dev;
160 	u32 mask; /* masks req and done down to queue size */
161 	u8 raw_addressing; /* use raw_addressing? */
162 
163 	/* Slow-path fields */
164 	u32 q_num ____cacheline_aligned; /* queue idx */
165 	u32 stop_queue; /* count of queue stops */
166 	u32 wake_queue; /* count of queue wakes */
167 	u32 ntfy_id; /* notification block index */
168 	dma_addr_t bus; /* dma address of the descr ring */
169 	dma_addr_t q_resources_bus; /* dma address of the queue resources */
170 	struct u64_stats_sync statss; /* sync stats for 32bit archs */
171 } ____cacheline_aligned;
172 
173 /* Wraps the info for one irq including the napi struct and the queues
174  * associated with that irq.
175  */
176 struct gve_notify_block {
177 	__be32 irq_db_index; /* idx into Bar2 - set by device, must be 1st */
178 	char name[IFNAMSIZ + 16]; /* name registered with the kernel */
179 	struct napi_struct napi; /* kernel napi struct for this block */
180 	struct gve_priv *priv;
181 	struct gve_tx_ring *tx; /* tx rings on this block */
182 	struct gve_rx_ring *rx; /* rx rings on this block */
183 } ____cacheline_aligned;
184 
185 /* Tracks allowed and current queue settings */
186 struct gve_queue_config {
187 	u16 max_queues;
188 	u16 num_queues; /* current */
189 };
190 
191 /* Tracks the available and used qpl IDs */
192 struct gve_qpl_config {
193 	u32 qpl_map_size; /* map memory size */
194 	unsigned long *qpl_id_map; /* bitmap of used qpl ids */
195 };
196 
197 struct gve_priv {
198 	struct net_device *dev;
199 	struct gve_tx_ring *tx; /* array of tx_cfg.num_queues */
200 	struct gve_rx_ring *rx; /* array of rx_cfg.num_queues */
201 	struct gve_queue_page_list *qpls; /* array of num qpls */
202 	struct gve_notify_block *ntfy_blocks; /* array of num_ntfy_blks */
203 	dma_addr_t ntfy_block_bus;
204 	struct msix_entry *msix_vectors; /* array of num_ntfy_blks + 1 */
205 	char mgmt_msix_name[IFNAMSIZ + 16];
206 	u32 mgmt_msix_idx;
207 	__be32 *counter_array; /* array of num_event_counters */
208 	dma_addr_t counter_array_bus;
209 
210 	u16 num_event_counters;
211 	u16 tx_desc_cnt; /* num desc per ring */
212 	u16 rx_desc_cnt; /* num desc per ring */
213 	u16 tx_pages_per_qpl; /* tx buffer length */
214 	u16 rx_data_slot_cnt; /* rx buffer length */
215 	u64 max_registered_pages;
216 	u64 num_registered_pages; /* num pages registered with NIC */
217 	u32 rx_copybreak; /* copy packets smaller than this */
218 	u16 default_num_queues; /* default num queues to set up */
219 	u8 raw_addressing; /* 1 if this dev supports raw addressing, 0 otherwise */
220 
221 	struct gve_queue_config tx_cfg;
222 	struct gve_queue_config rx_cfg;
223 	struct gve_qpl_config qpl_cfg; /* map used QPL ids */
224 	u32 num_ntfy_blks; /* spilt between TX and RX so must be even */
225 
226 	struct gve_registers __iomem *reg_bar0; /* see gve_register.h */
227 	__be32 __iomem *db_bar2; /* "array" of doorbells */
228 	u32 msg_enable;	/* level for netif* netdev print macros	*/
229 	struct pci_dev *pdev;
230 
231 	/* metrics */
232 	u32 tx_timeo_cnt;
233 
234 	/* Admin queue - see gve_adminq.h*/
235 	union gve_adminq_command *adminq;
236 	dma_addr_t adminq_bus_addr;
237 	u32 adminq_mask; /* masks prod_cnt to adminq size */
238 	u32 adminq_prod_cnt; /* free-running count of AQ cmds executed */
239 	u32 adminq_cmd_fail; /* free-running count of AQ cmds failed */
240 	u32 adminq_timeouts; /* free-running count of AQ cmds timeouts */
241 	/* free-running count of per AQ cmd executed */
242 	u32 adminq_describe_device_cnt;
243 	u32 adminq_cfg_device_resources_cnt;
244 	u32 adminq_register_page_list_cnt;
245 	u32 adminq_unregister_page_list_cnt;
246 	u32 adminq_create_tx_queue_cnt;
247 	u32 adminq_create_rx_queue_cnt;
248 	u32 adminq_destroy_tx_queue_cnt;
249 	u32 adminq_destroy_rx_queue_cnt;
250 	u32 adminq_dcfg_device_resources_cnt;
251 	u32 adminq_set_driver_parameter_cnt;
252 	u32 adminq_report_stats_cnt;
253 	u32 adminq_report_link_speed_cnt;
254 
255 	/* Global stats */
256 	u32 interface_up_cnt; /* count of times interface turned up since last reset */
257 	u32 interface_down_cnt; /* count of times interface turned down since last reset */
258 	u32 reset_cnt; /* count of reset */
259 	u32 page_alloc_fail; /* count of page alloc fails */
260 	u32 dma_mapping_error; /* count of dma mapping errors */
261 	u32 stats_report_trigger_cnt; /* count of device-requested stats-reports since last reset */
262 	struct workqueue_struct *gve_wq;
263 	struct work_struct service_task;
264 	struct work_struct stats_report_task;
265 	unsigned long service_task_flags;
266 	unsigned long state_flags;
267 
268 	struct gve_stats_report *stats_report;
269 	u64 stats_report_len;
270 	dma_addr_t stats_report_bus; /* dma address for the stats report */
271 	unsigned long ethtool_flags;
272 
273 	unsigned long stats_report_timer_period;
274 	struct timer_list stats_report_timer;
275 
276 	/* Gvnic device link speed from hypervisor. */
277 	u64 link_speed;
278 };
279 
280 enum gve_service_task_flags_bit {
281 	GVE_PRIV_FLAGS_DO_RESET			= 1,
282 	GVE_PRIV_FLAGS_RESET_IN_PROGRESS	= 2,
283 	GVE_PRIV_FLAGS_PROBE_IN_PROGRESS	= 3,
284 	GVE_PRIV_FLAGS_DO_REPORT_STATS = 4,
285 };
286 
287 enum gve_state_flags_bit {
288 	GVE_PRIV_FLAGS_ADMIN_QUEUE_OK		= 1,
289 	GVE_PRIV_FLAGS_DEVICE_RESOURCES_OK	= 2,
290 	GVE_PRIV_FLAGS_DEVICE_RINGS_OK		= 3,
291 	GVE_PRIV_FLAGS_NAPI_ENABLED		= 4,
292 };
293 
294 enum gve_ethtool_flags_bit {
295 	GVE_PRIV_FLAGS_REPORT_STATS		= 0,
296 };
297 
298 static inline bool gve_get_do_reset(struct gve_priv *priv)
299 {
300 	return test_bit(GVE_PRIV_FLAGS_DO_RESET, &priv->service_task_flags);
301 }
302 
303 static inline void gve_set_do_reset(struct gve_priv *priv)
304 {
305 	set_bit(GVE_PRIV_FLAGS_DO_RESET, &priv->service_task_flags);
306 }
307 
308 static inline void gve_clear_do_reset(struct gve_priv *priv)
309 {
310 	clear_bit(GVE_PRIV_FLAGS_DO_RESET, &priv->service_task_flags);
311 }
312 
313 static inline bool gve_get_reset_in_progress(struct gve_priv *priv)
314 {
315 	return test_bit(GVE_PRIV_FLAGS_RESET_IN_PROGRESS,
316 			&priv->service_task_flags);
317 }
318 
319 static inline void gve_set_reset_in_progress(struct gve_priv *priv)
320 {
321 	set_bit(GVE_PRIV_FLAGS_RESET_IN_PROGRESS, &priv->service_task_flags);
322 }
323 
324 static inline void gve_clear_reset_in_progress(struct gve_priv *priv)
325 {
326 	clear_bit(GVE_PRIV_FLAGS_RESET_IN_PROGRESS, &priv->service_task_flags);
327 }
328 
329 static inline bool gve_get_probe_in_progress(struct gve_priv *priv)
330 {
331 	return test_bit(GVE_PRIV_FLAGS_PROBE_IN_PROGRESS,
332 			&priv->service_task_flags);
333 }
334 
335 static inline void gve_set_probe_in_progress(struct gve_priv *priv)
336 {
337 	set_bit(GVE_PRIV_FLAGS_PROBE_IN_PROGRESS, &priv->service_task_flags);
338 }
339 
340 static inline void gve_clear_probe_in_progress(struct gve_priv *priv)
341 {
342 	clear_bit(GVE_PRIV_FLAGS_PROBE_IN_PROGRESS, &priv->service_task_flags);
343 }
344 
345 static inline bool gve_get_do_report_stats(struct gve_priv *priv)
346 {
347 	return test_bit(GVE_PRIV_FLAGS_DO_REPORT_STATS,
348 			&priv->service_task_flags);
349 }
350 
351 static inline void gve_set_do_report_stats(struct gve_priv *priv)
352 {
353 	set_bit(GVE_PRIV_FLAGS_DO_REPORT_STATS, &priv->service_task_flags);
354 }
355 
356 static inline void gve_clear_do_report_stats(struct gve_priv *priv)
357 {
358 	clear_bit(GVE_PRIV_FLAGS_DO_REPORT_STATS, &priv->service_task_flags);
359 }
360 
361 static inline bool gve_get_admin_queue_ok(struct gve_priv *priv)
362 {
363 	return test_bit(GVE_PRIV_FLAGS_ADMIN_QUEUE_OK, &priv->state_flags);
364 }
365 
366 static inline void gve_set_admin_queue_ok(struct gve_priv *priv)
367 {
368 	set_bit(GVE_PRIV_FLAGS_ADMIN_QUEUE_OK, &priv->state_flags);
369 }
370 
371 static inline void gve_clear_admin_queue_ok(struct gve_priv *priv)
372 {
373 	clear_bit(GVE_PRIV_FLAGS_ADMIN_QUEUE_OK, &priv->state_flags);
374 }
375 
376 static inline bool gve_get_device_resources_ok(struct gve_priv *priv)
377 {
378 	return test_bit(GVE_PRIV_FLAGS_DEVICE_RESOURCES_OK, &priv->state_flags);
379 }
380 
381 static inline void gve_set_device_resources_ok(struct gve_priv *priv)
382 {
383 	set_bit(GVE_PRIV_FLAGS_DEVICE_RESOURCES_OK, &priv->state_flags);
384 }
385 
386 static inline void gve_clear_device_resources_ok(struct gve_priv *priv)
387 {
388 	clear_bit(GVE_PRIV_FLAGS_DEVICE_RESOURCES_OK, &priv->state_flags);
389 }
390 
391 static inline bool gve_get_device_rings_ok(struct gve_priv *priv)
392 {
393 	return test_bit(GVE_PRIV_FLAGS_DEVICE_RINGS_OK, &priv->state_flags);
394 }
395 
396 static inline void gve_set_device_rings_ok(struct gve_priv *priv)
397 {
398 	set_bit(GVE_PRIV_FLAGS_DEVICE_RINGS_OK, &priv->state_flags);
399 }
400 
401 static inline void gve_clear_device_rings_ok(struct gve_priv *priv)
402 {
403 	clear_bit(GVE_PRIV_FLAGS_DEVICE_RINGS_OK, &priv->state_flags);
404 }
405 
406 static inline bool gve_get_napi_enabled(struct gve_priv *priv)
407 {
408 	return test_bit(GVE_PRIV_FLAGS_NAPI_ENABLED, &priv->state_flags);
409 }
410 
411 static inline void gve_set_napi_enabled(struct gve_priv *priv)
412 {
413 	set_bit(GVE_PRIV_FLAGS_NAPI_ENABLED, &priv->state_flags);
414 }
415 
416 static inline void gve_clear_napi_enabled(struct gve_priv *priv)
417 {
418 	clear_bit(GVE_PRIV_FLAGS_NAPI_ENABLED, &priv->state_flags);
419 }
420 
421 static inline bool gve_get_report_stats(struct gve_priv *priv)
422 {
423 	return test_bit(GVE_PRIV_FLAGS_REPORT_STATS, &priv->ethtool_flags);
424 }
425 
426 static inline void gve_clear_report_stats(struct gve_priv *priv)
427 {
428 	clear_bit(GVE_PRIV_FLAGS_REPORT_STATS, &priv->ethtool_flags);
429 }
430 
431 /* Returns the address of the ntfy_blocks irq doorbell
432  */
433 static inline __be32 __iomem *gve_irq_doorbell(struct gve_priv *priv,
434 					       struct gve_notify_block *block)
435 {
436 	return &priv->db_bar2[be32_to_cpu(block->irq_db_index)];
437 }
438 
439 /* Returns the index into ntfy_blocks of the given tx ring's block
440  */
441 static inline u32 gve_tx_idx_to_ntfy(struct gve_priv *priv, u32 queue_idx)
442 {
443 	return queue_idx;
444 }
445 
446 /* Returns the index into ntfy_blocks of the given rx ring's block
447  */
448 static inline u32 gve_rx_idx_to_ntfy(struct gve_priv *priv, u32 queue_idx)
449 {
450 	return (priv->num_ntfy_blks / 2) + queue_idx;
451 }
452 
453 /* Returns the number of tx queue page lists
454  */
455 static inline u32 gve_num_tx_qpls(struct gve_priv *priv)
456 {
457 	return priv->raw_addressing ? 0 : priv->tx_cfg.num_queues;
458 }
459 
460 /* Returns the number of rx queue page lists
461  */
462 static inline u32 gve_num_rx_qpls(struct gve_priv *priv)
463 {
464 	return priv->raw_addressing ? 0 : priv->rx_cfg.num_queues;
465 }
466 
467 /* Returns a pointer to the next available tx qpl in the list of qpls
468  */
469 static inline
470 struct gve_queue_page_list *gve_assign_tx_qpl(struct gve_priv *priv)
471 {
472 	int id = find_first_zero_bit(priv->qpl_cfg.qpl_id_map,
473 				     priv->qpl_cfg.qpl_map_size);
474 
475 	/* we are out of tx qpls */
476 	if (id >= gve_num_tx_qpls(priv))
477 		return NULL;
478 
479 	set_bit(id, priv->qpl_cfg.qpl_id_map);
480 	return &priv->qpls[id];
481 }
482 
483 /* Returns a pointer to the next available rx qpl in the list of qpls
484  */
485 static inline
486 struct gve_queue_page_list *gve_assign_rx_qpl(struct gve_priv *priv)
487 {
488 	int id = find_next_zero_bit(priv->qpl_cfg.qpl_id_map,
489 				    priv->qpl_cfg.qpl_map_size,
490 				    gve_num_tx_qpls(priv));
491 
492 	/* we are out of rx qpls */
493 	if (id == priv->qpl_cfg.qpl_map_size)
494 		return NULL;
495 
496 	set_bit(id, priv->qpl_cfg.qpl_id_map);
497 	return &priv->qpls[id];
498 }
499 
500 /* Unassigns the qpl with the given id
501  */
502 static inline void gve_unassign_qpl(struct gve_priv *priv, int id)
503 {
504 	clear_bit(id, priv->qpl_cfg.qpl_id_map);
505 }
506 
507 /* Returns the correct dma direction for tx and rx qpls
508  */
509 static inline enum dma_data_direction gve_qpl_dma_dir(struct gve_priv *priv,
510 						      int id)
511 {
512 	if (id < gve_num_tx_qpls(priv))
513 		return DMA_TO_DEVICE;
514 	else
515 		return DMA_FROM_DEVICE;
516 }
517 
518 /* buffers */
519 int gve_alloc_page(struct gve_priv *priv, struct device *dev,
520 		   struct page **page, dma_addr_t *dma,
521 		   enum dma_data_direction);
522 void gve_free_page(struct device *dev, struct page *page, dma_addr_t dma,
523 		   enum dma_data_direction);
524 /* tx handling */
525 netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev);
526 bool gve_tx_poll(struct gve_notify_block *block, int budget);
527 int gve_tx_alloc_rings(struct gve_priv *priv);
528 void gve_tx_free_rings(struct gve_priv *priv);
529 __be32 gve_tx_load_event_counter(struct gve_priv *priv,
530 				 struct gve_tx_ring *tx);
531 /* rx handling */
532 void gve_rx_write_doorbell(struct gve_priv *priv, struct gve_rx_ring *rx);
533 bool gve_rx_poll(struct gve_notify_block *block, int budget);
534 int gve_rx_alloc_rings(struct gve_priv *priv);
535 void gve_rx_free_rings(struct gve_priv *priv);
536 bool gve_clean_rx_done(struct gve_rx_ring *rx, int budget,
537 		       netdev_features_t feat);
538 /* Reset */
539 void gve_schedule_reset(struct gve_priv *priv);
540 int gve_reset(struct gve_priv *priv, bool attempt_teardown);
541 int gve_adjust_queues(struct gve_priv *priv,
542 		      struct gve_queue_config new_rx_config,
543 		      struct gve_queue_config new_tx_config);
544 /* report stats handling */
545 void gve_handle_report_stats(struct gve_priv *priv);
546 /* exported by ethtool.c */
547 extern const struct ethtool_ops gve_ethtool_ops;
548 /* needed by ethtool */
549 extern const char gve_version_str[];
550 #endif /* _GVE_H_ */
551