xref: /openbmc/linux/drivers/crypto/ccp/ccp-dev.h (revision e5c86679)
1 /*
2  * AMD Cryptographic Coprocessor (CCP) driver
3  *
4  * Copyright (C) 2013,2016 Advanced Micro Devices, Inc.
5  *
6  * Author: Tom Lendacky <thomas.lendacky@amd.com>
7  * Author: Gary R Hook <gary.hook@amd.com>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13 
14 #ifndef __CCP_DEV_H__
15 #define __CCP_DEV_H__
16 
17 #include <linux/device.h>
18 #include <linux/pci.h>
19 #include <linux/spinlock.h>
20 #include <linux/mutex.h>
21 #include <linux/list.h>
22 #include <linux/wait.h>
23 #include <linux/dmapool.h>
24 #include <linux/hw_random.h>
25 #include <linux/bitops.h>
26 #include <linux/interrupt.h>
27 #include <linux/irqreturn.h>
28 #include <linux/dmaengine.h>
29 
30 #define MAX_CCP_NAME_LEN		16
31 #define MAX_DMAPOOL_NAME_LEN		32
32 
33 #define MAX_HW_QUEUES			5
34 #define MAX_CMD_QLEN			100
35 
36 #define TRNG_RETRIES			10
37 
38 #define CACHE_NONE			0x00
39 #define CACHE_WB_NO_ALLOC		0xb7
40 
41 /****** Register Mappings ******/
42 #define Q_MASK_REG			0x000
43 #define TRNG_OUT_REG			0x00c
44 #define IRQ_MASK_REG			0x040
45 #define IRQ_STATUS_REG			0x200
46 
47 #define DEL_CMD_Q_JOB			0x124
48 #define DEL_Q_ACTIVE			0x00000200
49 #define DEL_Q_ID_SHIFT			6
50 
51 #define CMD_REQ0			0x180
52 #define CMD_REQ_INCR			0x04
53 
54 #define CMD_Q_STATUS_BASE		0x210
55 #define CMD_Q_INT_STATUS_BASE		0x214
56 #define CMD_Q_STATUS_INCR		0x20
57 
58 #define CMD_Q_CACHE_BASE		0x228
59 #define CMD_Q_CACHE_INC			0x20
60 
61 #define CMD_Q_ERROR(__qs)		((__qs) & 0x0000003f)
62 #define CMD_Q_DEPTH(__qs)		(((__qs) >> 12) & 0x0000000f)
63 
64 /* ------------------------ CCP Version 5 Specifics ------------------------ */
65 #define CMD5_QUEUE_MASK_OFFSET		0x00
66 #define	CMD5_QUEUE_PRIO_OFFSET		0x04
67 #define CMD5_REQID_CONFIG_OFFSET	0x08
68 #define	CMD5_CMD_TIMEOUT_OFFSET		0x10
69 #define LSB_PUBLIC_MASK_LO_OFFSET	0x18
70 #define LSB_PUBLIC_MASK_HI_OFFSET	0x1C
71 #define LSB_PRIVATE_MASK_LO_OFFSET	0x20
72 #define LSB_PRIVATE_MASK_HI_OFFSET	0x24
73 
74 #define CMD5_Q_CONTROL_BASE		0x0000
75 #define CMD5_Q_TAIL_LO_BASE		0x0004
76 #define CMD5_Q_HEAD_LO_BASE		0x0008
77 #define CMD5_Q_INT_ENABLE_BASE		0x000C
78 #define CMD5_Q_INTERRUPT_STATUS_BASE	0x0010
79 
80 #define CMD5_Q_STATUS_BASE		0x0100
81 #define CMD5_Q_INT_STATUS_BASE		0x0104
82 #define CMD5_Q_DMA_STATUS_BASE		0x0108
83 #define CMD5_Q_DMA_READ_STATUS_BASE	0x010C
84 #define CMD5_Q_DMA_WRITE_STATUS_BASE	0x0110
85 #define CMD5_Q_ABORT_BASE		0x0114
86 #define CMD5_Q_AX_CACHE_BASE		0x0118
87 
88 #define	CMD5_CONFIG_0_OFFSET		0x6000
89 #define	CMD5_TRNG_CTL_OFFSET		0x6008
90 #define	CMD5_AES_MASK_OFFSET		0x6010
91 #define	CMD5_CLK_GATE_CTL_OFFSET	0x603C
92 
93 /* Address offset between two virtual queue registers */
94 #define CMD5_Q_STATUS_INCR		0x1000
95 
96 /* Bit masks */
97 #define CMD5_Q_RUN			0x1
98 #define CMD5_Q_HALT			0x2
99 #define CMD5_Q_MEM_LOCATION		0x4
100 #define CMD5_Q_SIZE			0x1F
101 #define CMD5_Q_SHIFT			3
102 #define COMMANDS_PER_QUEUE		16
103 #define QUEUE_SIZE_VAL			((ffs(COMMANDS_PER_QUEUE) - 2) & \
104 					  CMD5_Q_SIZE)
105 #define Q_PTR_MASK			(2 << (QUEUE_SIZE_VAL + 5) - 1)
106 #define Q_DESC_SIZE			sizeof(struct ccp5_desc)
107 #define Q_SIZE(n)			(COMMANDS_PER_QUEUE*(n))
108 
109 #define INT_COMPLETION			0x1
110 #define INT_ERROR			0x2
111 #define INT_QUEUE_STOPPED		0x4
112 #define ALL_INTERRUPTS			(INT_COMPLETION| \
113 					 INT_ERROR| \
114 					 INT_QUEUE_STOPPED)
115 
116 #define LSB_REGION_WIDTH		5
117 #define MAX_LSB_CNT			8
118 
119 #define LSB_SIZE			16
120 #define LSB_ITEM_SIZE			32
121 #define PLSB_MAP_SIZE			(LSB_SIZE)
122 #define SLSB_MAP_SIZE			(MAX_LSB_CNT * LSB_SIZE)
123 
124 #define LSB_ENTRY_NUMBER(LSB_ADDR)	(LSB_ADDR / LSB_ITEM_SIZE)
125 
126 /* ------------------------ CCP Version 3 Specifics ------------------------ */
127 #define REQ0_WAIT_FOR_WRITE		0x00000004
128 #define REQ0_INT_ON_COMPLETE		0x00000002
129 #define REQ0_STOP_ON_COMPLETE		0x00000001
130 
131 #define REQ0_CMD_Q_SHIFT		9
132 #define REQ0_JOBID_SHIFT		3
133 
134 /****** REQ1 Related Values ******/
135 #define REQ1_PROTECT_SHIFT		27
136 #define REQ1_ENGINE_SHIFT		23
137 #define REQ1_KEY_KSB_SHIFT		2
138 
139 #define REQ1_EOM			0x00000002
140 #define REQ1_INIT			0x00000001
141 
142 /* AES Related Values */
143 #define REQ1_AES_TYPE_SHIFT		21
144 #define REQ1_AES_MODE_SHIFT		18
145 #define REQ1_AES_ACTION_SHIFT		17
146 #define REQ1_AES_CFB_SIZE_SHIFT		10
147 
148 /* XTS-AES Related Values */
149 #define REQ1_XTS_AES_SIZE_SHIFT		10
150 
151 /* SHA Related Values */
152 #define REQ1_SHA_TYPE_SHIFT		21
153 
154 /* RSA Related Values */
155 #define REQ1_RSA_MOD_SIZE_SHIFT		10
156 
157 /* Pass-Through Related Values */
158 #define REQ1_PT_BW_SHIFT		12
159 #define REQ1_PT_BS_SHIFT		10
160 
161 /* ECC Related Values */
162 #define REQ1_ECC_AFFINE_CONVERT		0x00200000
163 #define REQ1_ECC_FUNCTION_SHIFT		18
164 
165 /****** REQ4 Related Values ******/
166 #define REQ4_KSB_SHIFT			18
167 #define REQ4_MEMTYPE_SHIFT		16
168 
169 /****** REQ6 Related Values ******/
170 #define REQ6_MEMTYPE_SHIFT		16
171 
172 /****** Key Storage Block ******/
173 #define KSB_START			77
174 #define KSB_END				127
175 #define KSB_COUNT			(KSB_END - KSB_START + 1)
176 #define CCP_SB_BITS			256
177 
178 #define CCP_JOBID_MASK			0x0000003f
179 
180 /* ------------------------ General CCP Defines ------------------------ */
181 
182 #define	CCP_DMA_DFLT			0x0
183 #define	CCP_DMA_PRIV			0x1
184 #define	CCP_DMA_PUB			0x2
185 
186 #define CCP_DMAPOOL_MAX_SIZE		64
187 #define CCP_DMAPOOL_ALIGN		BIT(5)
188 
189 #define CCP_REVERSE_BUF_SIZE		64
190 
191 #define CCP_AES_KEY_SB_COUNT		1
192 #define CCP_AES_CTX_SB_COUNT		1
193 
194 #define CCP_XTS_AES_KEY_SB_COUNT	1
195 #define CCP_XTS_AES_CTX_SB_COUNT	1
196 
197 #define CCP_SHA_SB_COUNT		1
198 
199 #define CCP_RSA_MAX_WIDTH		4096
200 
201 #define CCP_PASSTHRU_BLOCKSIZE		256
202 #define CCP_PASSTHRU_MASKSIZE		32
203 #define CCP_PASSTHRU_SB_COUNT		1
204 
205 #define CCP_ECC_MODULUS_BYTES		48      /* 384-bits */
206 #define CCP_ECC_MAX_OPERANDS		6
207 #define CCP_ECC_MAX_OUTPUTS		3
208 #define CCP_ECC_SRC_BUF_SIZE		448
209 #define CCP_ECC_DST_BUF_SIZE		192
210 #define CCP_ECC_OPERAND_SIZE		64
211 #define CCP_ECC_OUTPUT_SIZE		64
212 #define CCP_ECC_RESULT_OFFSET		60
213 #define CCP_ECC_RESULT_SUCCESS		0x0001
214 
215 #define CCP_SB_BYTES			32
216 
217 struct ccp_op;
218 struct ccp_device;
219 struct ccp_cmd;
220 struct ccp_fns;
221 
222 struct ccp_dma_cmd {
223 	struct list_head entry;
224 
225 	struct ccp_cmd ccp_cmd;
226 };
227 
228 struct ccp_dma_desc {
229 	struct list_head entry;
230 
231 	struct ccp_device *ccp;
232 
233 	struct list_head pending;
234 	struct list_head active;
235 
236 	enum dma_status status;
237 	struct dma_async_tx_descriptor tx_desc;
238 	size_t len;
239 };
240 
241 struct ccp_dma_chan {
242 	struct ccp_device *ccp;
243 
244 	spinlock_t lock;
245 	struct list_head created;
246 	struct list_head pending;
247 	struct list_head active;
248 	struct list_head complete;
249 
250 	struct tasklet_struct cleanup_tasklet;
251 
252 	enum dma_status status;
253 	struct dma_chan dma_chan;
254 };
255 
256 struct ccp_cmd_queue {
257 	struct ccp_device *ccp;
258 
259 	/* Queue identifier */
260 	u32 id;
261 
262 	/* Queue dma pool */
263 	struct dma_pool *dma_pool;
264 
265 	/* Queue base address (not neccessarily aligned)*/
266 	struct ccp5_desc *qbase;
267 
268 	/* Aligned queue start address (per requirement) */
269 	struct mutex q_mutex ____cacheline_aligned;
270 	unsigned int qidx;
271 
272 	/* Version 5 has different requirements for queue memory */
273 	unsigned int qsize;
274 	dma_addr_t qbase_dma;
275 	dma_addr_t qdma_tail;
276 
277 	/* Per-queue reserved storage block(s) */
278 	u32 sb_key;
279 	u32 sb_ctx;
280 
281 	/* Bitmap of LSBs that can be accessed by this queue */
282 	DECLARE_BITMAP(lsbmask, MAX_LSB_CNT);
283 	/* Private LSB that is assigned to this queue, or -1 if none.
284 	 * Bitmap for my private LSB, unused otherwise
285 	 */
286 	int lsb;
287 	DECLARE_BITMAP(lsbmap, PLSB_MAP_SIZE);
288 
289 	/* Queue processing thread */
290 	struct task_struct *kthread;
291 	unsigned int active;
292 	unsigned int suspended;
293 
294 	/* Number of free command slots available */
295 	unsigned int free_slots;
296 
297 	/* Interrupt masks */
298 	u32 int_ok;
299 	u32 int_err;
300 
301 	/* Register addresses for queue */
302 	void __iomem *reg_control;
303 	void __iomem *reg_tail_lo;
304 	void __iomem *reg_head_lo;
305 	void __iomem *reg_int_enable;
306 	void __iomem *reg_interrupt_status;
307 	void __iomem *reg_status;
308 	void __iomem *reg_int_status;
309 	void __iomem *reg_dma_status;
310 	void __iomem *reg_dma_read_status;
311 	void __iomem *reg_dma_write_status;
312 	u32 qcontrol; /* Cached control register */
313 
314 	/* Status values from job */
315 	u32 int_status;
316 	u32 q_status;
317 	u32 q_int_status;
318 	u32 cmd_error;
319 
320 	/* Interrupt wait queue */
321 	wait_queue_head_t int_queue;
322 	unsigned int int_rcvd;
323 } ____cacheline_aligned;
324 
325 struct ccp_device {
326 	struct list_head entry;
327 
328 	struct ccp_vdata *vdata;
329 	unsigned int ord;
330 	char name[MAX_CCP_NAME_LEN];
331 	char rngname[MAX_CCP_NAME_LEN];
332 
333 	struct device *dev;
334 
335 	/* Bus specific device information
336 	 */
337 	void *dev_specific;
338 	int (*get_irq)(struct ccp_device *ccp);
339 	void (*free_irq)(struct ccp_device *ccp);
340 	unsigned int irq;
341 
342 	/* I/O area used for device communication. The register mapping
343 	 * starts at an offset into the mapped bar.
344 	 *   The CMD_REQx registers and the Delete_Cmd_Queue_Job register
345 	 *   need to be protected while a command queue thread is accessing
346 	 *   them.
347 	 */
348 	struct mutex req_mutex ____cacheline_aligned;
349 	void __iomem *io_map;
350 	void __iomem *io_regs;
351 
352 	/* Master lists that all cmds are queued on. Because there can be
353 	 * more than one CCP command queue that can process a cmd a separate
354 	 * backlog list is neeeded so that the backlog completion call
355 	 * completes before the cmd is available for execution.
356 	 */
357 	spinlock_t cmd_lock ____cacheline_aligned;
358 	unsigned int cmd_count;
359 	struct list_head cmd;
360 	struct list_head backlog;
361 
362 	/* The command queues. These represent the queues available on the
363 	 * CCP that are available for processing cmds
364 	 */
365 	struct ccp_cmd_queue cmd_q[MAX_HW_QUEUES];
366 	unsigned int cmd_q_count;
367 
368 	/* Support for the CCP True RNG
369 	 */
370 	struct hwrng hwrng;
371 	unsigned int hwrng_retries;
372 
373 	/* Support for the CCP DMA capabilities
374 	 */
375 	struct dma_device dma_dev;
376 	struct ccp_dma_chan *ccp_dma_chan;
377 	struct kmem_cache *dma_cmd_cache;
378 	struct kmem_cache *dma_desc_cache;
379 
380 	/* A counter used to generate job-ids for cmds submitted to the CCP
381 	 */
382 	atomic_t current_id ____cacheline_aligned;
383 
384 	/* The v3 CCP uses key storage blocks (SB) to maintain context for
385 	 * certain operations. To prevent multiple cmds from using the same
386 	 * SB range a command queue reserves an SB range for the duration of
387 	 * the cmd. Each queue, will however, reserve 2 SB blocks for
388 	 * operations that only require single SB entries (eg. AES context/iv
389 	 * and key) in order to avoid allocation contention.  This will reserve
390 	 * at most 10 SB entries, leaving 40 SB entries available for dynamic
391 	 * allocation.
392 	 *
393 	 * The v5 CCP Local Storage Block (LSB) is broken up into 8
394 	 * memrory ranges, each of which can be enabled for access by one
395 	 * or more queues. Device initialization takes this into account,
396 	 * and attempts to assign one region for exclusive use by each
397 	 * available queue; the rest are then aggregated as "public" use.
398 	 * If there are fewer regions than queues, all regions are shared
399 	 * amongst all queues.
400 	 */
401 	struct mutex sb_mutex ____cacheline_aligned;
402 	DECLARE_BITMAP(sb, KSB_COUNT);
403 	wait_queue_head_t sb_queue;
404 	unsigned int sb_avail;
405 	unsigned int sb_count;
406 	u32 sb_start;
407 
408 	/* Bitmap of shared LSBs, if any */
409 	DECLARE_BITMAP(lsbmap, SLSB_MAP_SIZE);
410 
411 	/* Suspend support */
412 	unsigned int suspending;
413 	wait_queue_head_t suspend_queue;
414 
415 	/* DMA caching attribute support */
416 	unsigned int axcache;
417 };
418 
419 enum ccp_memtype {
420 	CCP_MEMTYPE_SYSTEM = 0,
421 	CCP_MEMTYPE_SB,
422 	CCP_MEMTYPE_LOCAL,
423 	CCP_MEMTYPE__LAST,
424 };
425 #define	CCP_MEMTYPE_LSB	CCP_MEMTYPE_KSB
426 
427 struct ccp_dma_info {
428 	dma_addr_t address;
429 	unsigned int offset;
430 	unsigned int length;
431 	enum dma_data_direction dir;
432 };
433 
434 struct ccp_dm_workarea {
435 	struct device *dev;
436 	struct dma_pool *dma_pool;
437 	unsigned int length;
438 
439 	u8 *address;
440 	struct ccp_dma_info dma;
441 };
442 
443 struct ccp_sg_workarea {
444 	struct scatterlist *sg;
445 	int nents;
446 
447 	struct scatterlist *dma_sg;
448 	struct device *dma_dev;
449 	unsigned int dma_count;
450 	enum dma_data_direction dma_dir;
451 
452 	unsigned int sg_used;
453 
454 	u64 bytes_left;
455 };
456 
457 struct ccp_data {
458 	struct ccp_sg_workarea sg_wa;
459 	struct ccp_dm_workarea dm_wa;
460 };
461 
462 struct ccp_mem {
463 	enum ccp_memtype type;
464 	union {
465 		struct ccp_dma_info dma;
466 		u32 sb;
467 	} u;
468 };
469 
470 struct ccp_aes_op {
471 	enum ccp_aes_type type;
472 	enum ccp_aes_mode mode;
473 	enum ccp_aes_action action;
474 	unsigned int size;
475 };
476 
477 struct ccp_xts_aes_op {
478 	enum ccp_aes_action action;
479 	enum ccp_xts_aes_unit_size unit_size;
480 };
481 
482 struct ccp_sha_op {
483 	enum ccp_sha_type type;
484 	u64 msg_bits;
485 };
486 
487 struct ccp_rsa_op {
488 	u32 mod_size;
489 	u32 input_len;
490 };
491 
492 struct ccp_passthru_op {
493 	enum ccp_passthru_bitwise bit_mod;
494 	enum ccp_passthru_byteswap byte_swap;
495 };
496 
497 struct ccp_ecc_op {
498 	enum ccp_ecc_function function;
499 };
500 
501 struct ccp_op {
502 	struct ccp_cmd_queue *cmd_q;
503 
504 	u32 jobid;
505 	u32 ioc;
506 	u32 soc;
507 	u32 sb_key;
508 	u32 sb_ctx;
509 	u32 init;
510 	u32 eom;
511 
512 	struct ccp_mem src;
513 	struct ccp_mem dst;
514 	struct ccp_mem exp;
515 
516 	union {
517 		struct ccp_aes_op aes;
518 		struct ccp_xts_aes_op xts;
519 		struct ccp_sha_op sha;
520 		struct ccp_rsa_op rsa;
521 		struct ccp_passthru_op passthru;
522 		struct ccp_ecc_op ecc;
523 	} u;
524 };
525 
526 static inline u32 ccp_addr_lo(struct ccp_dma_info *info)
527 {
528 	return lower_32_bits(info->address + info->offset);
529 }
530 
531 static inline u32 ccp_addr_hi(struct ccp_dma_info *info)
532 {
533 	return upper_32_bits(info->address + info->offset) & 0x0000ffff;
534 }
535 
536 /**
537  * descriptor for version 5 CPP commands
538  * 8 32-bit words:
539  * word 0: function; engine; control bits
540  * word 1: length of source data
541  * word 2: low 32 bits of source pointer
542  * word 3: upper 16 bits of source pointer; source memory type
543  * word 4: low 32 bits of destination pointer
544  * word 5: upper 16 bits of destination pointer; destination memory type
545  * word 6: low 32 bits of key pointer
546  * word 7: upper 16 bits of key pointer; key memory type
547  */
548 struct dword0 {
549 	unsigned int soc:1;
550 	unsigned int ioc:1;
551 	unsigned int rsvd1:1;
552 	unsigned int init:1;
553 	unsigned int eom:1;		/* AES/SHA only */
554 	unsigned int function:15;
555 	unsigned int engine:4;
556 	unsigned int prot:1;
557 	unsigned int rsvd2:7;
558 };
559 
560 struct dword3 {
561 	unsigned int  src_hi:16;
562 	unsigned int  src_mem:2;
563 	unsigned int  lsb_cxt_id:8;
564 	unsigned int  rsvd1:5;
565 	unsigned int  fixed:1;
566 };
567 
568 union dword4 {
569 	__le32 dst_lo;		/* NON-SHA	*/
570 	__le32 sha_len_lo;	/* SHA		*/
571 };
572 
573 union dword5 {
574 	struct {
575 		unsigned int  dst_hi:16;
576 		unsigned int  dst_mem:2;
577 		unsigned int  rsvd1:13;
578 		unsigned int  fixed:1;
579 	} fields;
580 	__le32 sha_len_hi;
581 };
582 
583 struct dword7 {
584 	unsigned int  key_hi:16;
585 	unsigned int  key_mem:2;
586 	unsigned int  rsvd1:14;
587 };
588 
589 struct ccp5_desc {
590 	struct dword0 dw0;
591 	__le32 length;
592 	__le32 src_lo;
593 	struct dword3 dw3;
594 	union dword4 dw4;
595 	union dword5 dw5;
596 	__le32 key_lo;
597 	struct dword7 dw7;
598 };
599 
600 int ccp_pci_init(void);
601 void ccp_pci_exit(void);
602 
603 int ccp_platform_init(void);
604 void ccp_platform_exit(void);
605 
606 void ccp_add_device(struct ccp_device *ccp);
607 void ccp_del_device(struct ccp_device *ccp);
608 
609 extern void ccp_log_error(struct ccp_device *, int);
610 
611 struct ccp_device *ccp_alloc_struct(struct device *dev);
612 bool ccp_queues_suspended(struct ccp_device *ccp);
613 int ccp_cmd_queue_thread(void *data);
614 int ccp_trng_read(struct hwrng *rng, void *data, size_t max, bool wait);
615 
616 int ccp_run_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd);
617 
618 int ccp_register_rng(struct ccp_device *ccp);
619 void ccp_unregister_rng(struct ccp_device *ccp);
620 int ccp_dmaengine_register(struct ccp_device *ccp);
621 void ccp_dmaengine_unregister(struct ccp_device *ccp);
622 
623 /* Structure for computation functions that are device-specific */
624 struct ccp_actions {
625 	int (*aes)(struct ccp_op *);
626 	int (*xts_aes)(struct ccp_op *);
627 	int (*sha)(struct ccp_op *);
628 	int (*rsa)(struct ccp_op *);
629 	int (*passthru)(struct ccp_op *);
630 	int (*ecc)(struct ccp_op *);
631 	u32 (*sballoc)(struct ccp_cmd_queue *, unsigned int);
632 	void (*sbfree)(struct ccp_cmd_queue *, unsigned int,
633 			       unsigned int);
634 	unsigned int (*get_free_slots)(struct ccp_cmd_queue *);
635 	int (*init)(struct ccp_device *);
636 	void (*destroy)(struct ccp_device *);
637 	irqreturn_t (*irqhandler)(int, void *);
638 };
639 
640 /* Structure to hold CCP version-specific values */
641 struct ccp_vdata {
642 	const unsigned int version;
643 	const unsigned int dma_chan_attr;
644 	void (*setup)(struct ccp_device *);
645 	const struct ccp_actions *perform;
646 	const unsigned int bar;
647 	const unsigned int offset;
648 };
649 
650 extern const struct ccp_vdata ccpv3;
651 extern const struct ccp_vdata ccpv5a;
652 extern const struct ccp_vdata ccpv5b;
653 
654 #endif
655