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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
4  *		  2002-2006 Thomas Gleixner (tglx@linutronix.de)
5  *
6  *  Credits:
7  *	David Woodhouse for adding multichip support
8  *
9  *	Aleph One Ltd. and Toby Churchill Ltd. for supporting the
10  *	rework for 2K page size chips
11  *
12  * This file contains all legacy helpers/code that should be removed
13  * at some point.
14  */
15 
16 #include <linux/delay.h>
17 #include <linux/io.h>
18 #include <linux/nmi.h>
19 
20 #include "internals.h"
21 
22 /**
23  * nand_read_byte - [DEFAULT] read one byte from the chip
24  * @chip: NAND chip object
25  *
26  * Default read function for 8bit buswidth
27  */
nand_read_byte(struct nand_chip * chip)28 static uint8_t nand_read_byte(struct nand_chip *chip)
29 {
30 	return readb(chip->legacy.IO_ADDR_R);
31 }
32 
33 /**
34  * nand_read_byte16 - [DEFAULT] read one byte endianness aware from the chip
35  * @chip: NAND chip object
36  *
37  * Default read function for 16bit buswidth with endianness conversion.
38  *
39  */
nand_read_byte16(struct nand_chip * chip)40 static uint8_t nand_read_byte16(struct nand_chip *chip)
41 {
42 	return (uint8_t) cpu_to_le16(readw(chip->legacy.IO_ADDR_R));
43 }
44 
45 /**
46  * nand_select_chip - [DEFAULT] control CE line
47  * @chip: NAND chip object
48  * @chipnr: chipnumber to select, -1 for deselect
49  *
50  * Default select function for 1 chip devices.
51  */
nand_select_chip(struct nand_chip * chip,int chipnr)52 static void nand_select_chip(struct nand_chip *chip, int chipnr)
53 {
54 	switch (chipnr) {
55 	case -1:
56 		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
57 				      0 | NAND_CTRL_CHANGE);
58 		break;
59 	case 0:
60 		break;
61 
62 	default:
63 		BUG();
64 	}
65 }
66 
67 /**
68  * nand_write_byte - [DEFAULT] write single byte to chip
69  * @chip: NAND chip object
70  * @byte: value to write
71  *
72  * Default function to write a byte to I/O[7:0]
73  */
nand_write_byte(struct nand_chip * chip,uint8_t byte)74 static void nand_write_byte(struct nand_chip *chip, uint8_t byte)
75 {
76 	chip->legacy.write_buf(chip, &byte, 1);
77 }
78 
79 /**
80  * nand_write_byte16 - [DEFAULT] write single byte to a chip with width 16
81  * @chip: NAND chip object
82  * @byte: value to write
83  *
84  * Default function to write a byte to I/O[7:0] on a 16-bit wide chip.
85  */
nand_write_byte16(struct nand_chip * chip,uint8_t byte)86 static void nand_write_byte16(struct nand_chip *chip, uint8_t byte)
87 {
88 	uint16_t word = byte;
89 
90 	/*
91 	 * It's not entirely clear what should happen to I/O[15:8] when writing
92 	 * a byte. The ONFi spec (Revision 3.1; 2012-09-19, Section 2.16) reads:
93 	 *
94 	 *    When the host supports a 16-bit bus width, only data is
95 	 *    transferred at the 16-bit width. All address and command line
96 	 *    transfers shall use only the lower 8-bits of the data bus. During
97 	 *    command transfers, the host may place any value on the upper
98 	 *    8-bits of the data bus. During address transfers, the host shall
99 	 *    set the upper 8-bits of the data bus to 00h.
100 	 *
101 	 * One user of the write_byte callback is nand_set_features. The
102 	 * four parameters are specified to be written to I/O[7:0], but this is
103 	 * neither an address nor a command transfer. Let's assume a 0 on the
104 	 * upper I/O lines is OK.
105 	 */
106 	chip->legacy.write_buf(chip, (uint8_t *)&word, 2);
107 }
108 
109 /**
110  * nand_write_buf - [DEFAULT] write buffer to chip
111  * @chip: NAND chip object
112  * @buf: data buffer
113  * @len: number of bytes to write
114  *
115  * Default write function for 8bit buswidth.
116  */
nand_write_buf(struct nand_chip * chip,const uint8_t * buf,int len)117 static void nand_write_buf(struct nand_chip *chip, const uint8_t *buf, int len)
118 {
119 	iowrite8_rep(chip->legacy.IO_ADDR_W, buf, len);
120 }
121 
122 /**
123  * nand_read_buf - [DEFAULT] read chip data into buffer
124  * @chip: NAND chip object
125  * @buf: buffer to store date
126  * @len: number of bytes to read
127  *
128  * Default read function for 8bit buswidth.
129  */
nand_read_buf(struct nand_chip * chip,uint8_t * buf,int len)130 static void nand_read_buf(struct nand_chip *chip, uint8_t *buf, int len)
131 {
132 	ioread8_rep(chip->legacy.IO_ADDR_R, buf, len);
133 }
134 
135 /**
136  * nand_write_buf16 - [DEFAULT] write buffer to chip
137  * @chip: NAND chip object
138  * @buf: data buffer
139  * @len: number of bytes to write
140  *
141  * Default write function for 16bit buswidth.
142  */
nand_write_buf16(struct nand_chip * chip,const uint8_t * buf,int len)143 static void nand_write_buf16(struct nand_chip *chip, const uint8_t *buf,
144 			     int len)
145 {
146 	u16 *p = (u16 *) buf;
147 
148 	iowrite16_rep(chip->legacy.IO_ADDR_W, p, len >> 1);
149 }
150 
151 /**
152  * nand_read_buf16 - [DEFAULT] read chip data into buffer
153  * @chip: NAND chip object
154  * @buf: buffer to store date
155  * @len: number of bytes to read
156  *
157  * Default read function for 16bit buswidth.
158  */
nand_read_buf16(struct nand_chip * chip,uint8_t * buf,int len)159 static void nand_read_buf16(struct nand_chip *chip, uint8_t *buf, int len)
160 {
161 	u16 *p = (u16 *) buf;
162 
163 	ioread16_rep(chip->legacy.IO_ADDR_R, p, len >> 1);
164 }
165 
166 /**
167  * panic_nand_wait_ready - [GENERIC] Wait for the ready pin after commands.
168  * @chip: NAND chip object
169  * @timeo: Timeout
170  *
171  * Helper function for nand_wait_ready used when needing to wait in interrupt
172  * context.
173  */
panic_nand_wait_ready(struct nand_chip * chip,unsigned long timeo)174 static void panic_nand_wait_ready(struct nand_chip *chip, unsigned long timeo)
175 {
176 	int i;
177 
178 	/* Wait for the device to get ready */
179 	for (i = 0; i < timeo; i++) {
180 		if (chip->legacy.dev_ready(chip))
181 			break;
182 		touch_softlockup_watchdog();
183 		mdelay(1);
184 	}
185 }
186 
187 /**
188  * nand_wait_ready - [GENERIC] Wait for the ready pin after commands.
189  * @chip: NAND chip object
190  *
191  * Wait for the ready pin after a command, and warn if a timeout occurs.
192  */
nand_wait_ready(struct nand_chip * chip)193 void nand_wait_ready(struct nand_chip *chip)
194 {
195 	unsigned long timeo = 400;
196 
197 	if (in_interrupt() || oops_in_progress)
198 		return panic_nand_wait_ready(chip, timeo);
199 
200 	/* Wait until command is processed or timeout occurs */
201 	timeo = jiffies + msecs_to_jiffies(timeo);
202 	do {
203 		if (chip->legacy.dev_ready(chip))
204 			return;
205 		cond_resched();
206 	} while (time_before(jiffies, timeo));
207 
208 	if (!chip->legacy.dev_ready(chip))
209 		pr_warn_ratelimited("timeout while waiting for chip to become ready\n");
210 }
211 EXPORT_SYMBOL_GPL(nand_wait_ready);
212 
213 /**
214  * nand_wait_status_ready - [GENERIC] Wait for the ready status after commands.
215  * @chip: NAND chip object
216  * @timeo: Timeout in ms
217  *
218  * Wait for status ready (i.e. command done) or timeout.
219  */
nand_wait_status_ready(struct nand_chip * chip,unsigned long timeo)220 static void nand_wait_status_ready(struct nand_chip *chip, unsigned long timeo)
221 {
222 	int ret;
223 
224 	timeo = jiffies + msecs_to_jiffies(timeo);
225 	do {
226 		u8 status;
227 
228 		ret = nand_read_data_op(chip, &status, sizeof(status), true,
229 					false);
230 		if (ret)
231 			return;
232 
233 		if (status & NAND_STATUS_READY)
234 			break;
235 		touch_softlockup_watchdog();
236 	} while (time_before(jiffies, timeo));
237 };
238 
239 /**
240  * nand_command - [DEFAULT] Send command to NAND device
241  * @chip: NAND chip object
242  * @command: the command to be sent
243  * @column: the column address for this command, -1 if none
244  * @page_addr: the page address for this command, -1 if none
245  *
246  * Send command to NAND device. This function is used for small page devices
247  * (512 Bytes per page).
248  */
nand_command(struct nand_chip * chip,unsigned int command,int column,int page_addr)249 static void nand_command(struct nand_chip *chip, unsigned int command,
250 			 int column, int page_addr)
251 {
252 	struct mtd_info *mtd = nand_to_mtd(chip);
253 	int ctrl = NAND_CTRL_CLE | NAND_CTRL_CHANGE;
254 
255 	/* Write out the command to the device */
256 	if (command == NAND_CMD_SEQIN) {
257 		int readcmd;
258 
259 		if (column >= mtd->writesize) {
260 			/* OOB area */
261 			column -= mtd->writesize;
262 			readcmd = NAND_CMD_READOOB;
263 		} else if (column < 256) {
264 			/* First 256 bytes --> READ0 */
265 			readcmd = NAND_CMD_READ0;
266 		} else {
267 			column -= 256;
268 			readcmd = NAND_CMD_READ1;
269 		}
270 		chip->legacy.cmd_ctrl(chip, readcmd, ctrl);
271 		ctrl &= ~NAND_CTRL_CHANGE;
272 	}
273 	if (command != NAND_CMD_NONE)
274 		chip->legacy.cmd_ctrl(chip, command, ctrl);
275 
276 	/* Address cycle, when necessary */
277 	ctrl = NAND_CTRL_ALE | NAND_CTRL_CHANGE;
278 	/* Serially input address */
279 	if (column != -1) {
280 		/* Adjust columns for 16 bit buswidth */
281 		if (chip->options & NAND_BUSWIDTH_16 &&
282 				!nand_opcode_8bits(command))
283 			column >>= 1;
284 		chip->legacy.cmd_ctrl(chip, column, ctrl);
285 		ctrl &= ~NAND_CTRL_CHANGE;
286 	}
287 	if (page_addr != -1) {
288 		chip->legacy.cmd_ctrl(chip, page_addr, ctrl);
289 		ctrl &= ~NAND_CTRL_CHANGE;
290 		chip->legacy.cmd_ctrl(chip, page_addr >> 8, ctrl);
291 		if (chip->options & NAND_ROW_ADDR_3)
292 			chip->legacy.cmd_ctrl(chip, page_addr >> 16, ctrl);
293 	}
294 	chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
295 			      NAND_NCE | NAND_CTRL_CHANGE);
296 
297 	/*
298 	 * Program and erase have their own busy handlers status and sequential
299 	 * in needs no delay
300 	 */
301 	switch (command) {
302 
303 	case NAND_CMD_NONE:
304 	case NAND_CMD_PAGEPROG:
305 	case NAND_CMD_ERASE1:
306 	case NAND_CMD_ERASE2:
307 	case NAND_CMD_SEQIN:
308 	case NAND_CMD_STATUS:
309 	case NAND_CMD_READID:
310 	case NAND_CMD_SET_FEATURES:
311 		return;
312 
313 	case NAND_CMD_RESET:
314 		if (chip->legacy.dev_ready)
315 			break;
316 		udelay(chip->legacy.chip_delay);
317 		chip->legacy.cmd_ctrl(chip, NAND_CMD_STATUS,
318 				      NAND_CTRL_CLE | NAND_CTRL_CHANGE);
319 		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
320 				      NAND_NCE | NAND_CTRL_CHANGE);
321 		/* EZ-NAND can take upto 250ms as per ONFi v4.0 */
322 		nand_wait_status_ready(chip, 250);
323 		return;
324 
325 		/* This applies to read commands */
326 	case NAND_CMD_READ0:
327 		/*
328 		 * READ0 is sometimes used to exit GET STATUS mode. When this
329 		 * is the case no address cycles are requested, and we can use
330 		 * this information to detect that we should not wait for the
331 		 * device to be ready.
332 		 */
333 		if (column == -1 && page_addr == -1)
334 			return;
335 		fallthrough;
336 	default:
337 		/*
338 		 * If we don't have access to the busy pin, we apply the given
339 		 * command delay
340 		 */
341 		if (!chip->legacy.dev_ready) {
342 			udelay(chip->legacy.chip_delay);
343 			return;
344 		}
345 	}
346 	/*
347 	 * Apply this short delay always to ensure that we do wait tWB in
348 	 * any case on any machine.
349 	 */
350 	ndelay(100);
351 
352 	nand_wait_ready(chip);
353 }
354 
nand_ccs_delay(struct nand_chip * chip)355 static void nand_ccs_delay(struct nand_chip *chip)
356 {
357 	const struct nand_sdr_timings *sdr =
358 		nand_get_sdr_timings(nand_get_interface_config(chip));
359 
360 	/*
361 	 * The controller already takes care of waiting for tCCS when the RNDIN
362 	 * or RNDOUT command is sent, return directly.
363 	 */
364 	if (!(chip->options & NAND_WAIT_TCCS))
365 		return;
366 
367 	/*
368 	 * Wait tCCS_min if it is correctly defined, otherwise wait 500ns
369 	 * (which should be safe for all NANDs).
370 	 */
371 	if (nand_controller_can_setup_interface(chip))
372 		ndelay(sdr->tCCS_min / 1000);
373 	else
374 		ndelay(500);
375 }
376 
377 /**
378  * nand_command_lp - [DEFAULT] Send command to NAND large page device
379  * @chip: NAND chip object
380  * @command: the command to be sent
381  * @column: the column address for this command, -1 if none
382  * @page_addr: the page address for this command, -1 if none
383  *
384  * Send command to NAND device. This is the version for the new large page
385  * devices. We don't have the separate regions as we have in the small page
386  * devices. We must emulate NAND_CMD_READOOB to keep the code compatible.
387  */
nand_command_lp(struct nand_chip * chip,unsigned int command,int column,int page_addr)388 static void nand_command_lp(struct nand_chip *chip, unsigned int command,
389 			    int column, int page_addr)
390 {
391 	struct mtd_info *mtd = nand_to_mtd(chip);
392 
393 	/* Emulate NAND_CMD_READOOB */
394 	if (command == NAND_CMD_READOOB) {
395 		column += mtd->writesize;
396 		command = NAND_CMD_READ0;
397 	}
398 
399 	/* Command latch cycle */
400 	if (command != NAND_CMD_NONE)
401 		chip->legacy.cmd_ctrl(chip, command,
402 				      NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
403 
404 	if (column != -1 || page_addr != -1) {
405 		int ctrl = NAND_CTRL_CHANGE | NAND_NCE | NAND_ALE;
406 
407 		/* Serially input address */
408 		if (column != -1) {
409 			/* Adjust columns for 16 bit buswidth */
410 			if (chip->options & NAND_BUSWIDTH_16 &&
411 					!nand_opcode_8bits(command))
412 				column >>= 1;
413 			chip->legacy.cmd_ctrl(chip, column, ctrl);
414 			ctrl &= ~NAND_CTRL_CHANGE;
415 
416 			/* Only output a single addr cycle for 8bits opcodes. */
417 			if (!nand_opcode_8bits(command))
418 				chip->legacy.cmd_ctrl(chip, column >> 8, ctrl);
419 		}
420 		if (page_addr != -1) {
421 			chip->legacy.cmd_ctrl(chip, page_addr, ctrl);
422 			chip->legacy.cmd_ctrl(chip, page_addr >> 8,
423 					     NAND_NCE | NAND_ALE);
424 			if (chip->options & NAND_ROW_ADDR_3)
425 				chip->legacy.cmd_ctrl(chip, page_addr >> 16,
426 						      NAND_NCE | NAND_ALE);
427 		}
428 	}
429 	chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
430 			      NAND_NCE | NAND_CTRL_CHANGE);
431 
432 	/*
433 	 * Program and erase have their own busy handlers status, sequential
434 	 * in and status need no delay.
435 	 */
436 	switch (command) {
437 
438 	case NAND_CMD_NONE:
439 	case NAND_CMD_CACHEDPROG:
440 	case NAND_CMD_PAGEPROG:
441 	case NAND_CMD_ERASE1:
442 	case NAND_CMD_ERASE2:
443 	case NAND_CMD_SEQIN:
444 	case NAND_CMD_STATUS:
445 	case NAND_CMD_READID:
446 	case NAND_CMD_SET_FEATURES:
447 		return;
448 
449 	case NAND_CMD_RNDIN:
450 		nand_ccs_delay(chip);
451 		return;
452 
453 	case NAND_CMD_RESET:
454 		if (chip->legacy.dev_ready)
455 			break;
456 		udelay(chip->legacy.chip_delay);
457 		chip->legacy.cmd_ctrl(chip, NAND_CMD_STATUS,
458 				      NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
459 		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
460 				      NAND_NCE | NAND_CTRL_CHANGE);
461 		/* EZ-NAND can take upto 250ms as per ONFi v4.0 */
462 		nand_wait_status_ready(chip, 250);
463 		return;
464 
465 	case NAND_CMD_RNDOUT:
466 		/* No ready / busy check necessary */
467 		chip->legacy.cmd_ctrl(chip, NAND_CMD_RNDOUTSTART,
468 				      NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
469 		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
470 				      NAND_NCE | NAND_CTRL_CHANGE);
471 
472 		nand_ccs_delay(chip);
473 		return;
474 
475 	case NAND_CMD_READ0:
476 		/*
477 		 * READ0 is sometimes used to exit GET STATUS mode. When this
478 		 * is the case no address cycles are requested, and we can use
479 		 * this information to detect that READSTART should not be
480 		 * issued.
481 		 */
482 		if (column == -1 && page_addr == -1)
483 			return;
484 
485 		chip->legacy.cmd_ctrl(chip, NAND_CMD_READSTART,
486 				      NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
487 		chip->legacy.cmd_ctrl(chip, NAND_CMD_NONE,
488 				      NAND_NCE | NAND_CTRL_CHANGE);
489 		fallthrough;	/* This applies to read commands */
490 	default:
491 		/*
492 		 * If we don't have access to the busy pin, we apply the given
493 		 * command delay.
494 		 */
495 		if (!chip->legacy.dev_ready) {
496 			udelay(chip->legacy.chip_delay);
497 			return;
498 		}
499 	}
500 
501 	/*
502 	 * Apply this short delay always to ensure that we do wait tWB in
503 	 * any case on any machine.
504 	 */
505 	ndelay(100);
506 
507 	nand_wait_ready(chip);
508 }
509 
510 /**
511  * nand_get_set_features_notsupp - set/get features stub returning -ENOTSUPP
512  * @chip: nand chip info structure
513  * @addr: feature address.
514  * @subfeature_param: the subfeature parameters, a four bytes array.
515  *
516  * Should be used by NAND controller drivers that do not support the SET/GET
517  * FEATURES operations.
518  */
nand_get_set_features_notsupp(struct nand_chip * chip,int addr,u8 * subfeature_param)519 int nand_get_set_features_notsupp(struct nand_chip *chip, int addr,
520 				  u8 *subfeature_param)
521 {
522 	return -ENOTSUPP;
523 }
524 EXPORT_SYMBOL(nand_get_set_features_notsupp);
525 
526 /**
527  * nand_wait - [DEFAULT] wait until the command is done
528  * @chip: NAND chip structure
529  *
530  * Wait for command done. This applies to erase and program only.
531  */
nand_wait(struct nand_chip * chip)532 static int nand_wait(struct nand_chip *chip)
533 {
534 
535 	unsigned long timeo = 400;
536 	u8 status;
537 	int ret;
538 
539 	/*
540 	 * Apply this short delay always to ensure that we do wait tWB in any
541 	 * case on any machine.
542 	 */
543 	ndelay(100);
544 
545 	ret = nand_status_op(chip, NULL);
546 	if (ret)
547 		return ret;
548 
549 	if (in_interrupt() || oops_in_progress)
550 		panic_nand_wait(chip, timeo);
551 	else {
552 		timeo = jiffies + msecs_to_jiffies(timeo);
553 		do {
554 			if (chip->legacy.dev_ready) {
555 				if (chip->legacy.dev_ready(chip))
556 					break;
557 			} else {
558 				ret = nand_read_data_op(chip, &status,
559 							sizeof(status), true,
560 							false);
561 				if (ret)
562 					return ret;
563 
564 				if (status & NAND_STATUS_READY)
565 					break;
566 			}
567 			cond_resched();
568 		} while (time_before(jiffies, timeo));
569 	}
570 
571 	ret = nand_read_data_op(chip, &status, sizeof(status), true, false);
572 	if (ret)
573 		return ret;
574 
575 	/* This can happen if in case of timeout or buggy dev_ready */
576 	WARN_ON(!(status & NAND_STATUS_READY));
577 	return status;
578 }
579 
nand_legacy_set_defaults(struct nand_chip * chip)580 void nand_legacy_set_defaults(struct nand_chip *chip)
581 {
582 	unsigned int busw = chip->options & NAND_BUSWIDTH_16;
583 
584 	if (nand_has_exec_op(chip))
585 		return;
586 
587 	/* check for proper chip_delay setup, set 20us if not */
588 	if (!chip->legacy.chip_delay)
589 		chip->legacy.chip_delay = 20;
590 
591 	/* check, if a user supplied command function given */
592 	if (!chip->legacy.cmdfunc)
593 		chip->legacy.cmdfunc = nand_command;
594 
595 	/* check, if a user supplied wait function given */
596 	if (chip->legacy.waitfunc == NULL)
597 		chip->legacy.waitfunc = nand_wait;
598 
599 	if (!chip->legacy.select_chip)
600 		chip->legacy.select_chip = nand_select_chip;
601 
602 	/* If called twice, pointers that depend on busw may need to be reset */
603 	if (!chip->legacy.read_byte || chip->legacy.read_byte == nand_read_byte)
604 		chip->legacy.read_byte = busw ? nand_read_byte16 : nand_read_byte;
605 	if (!chip->legacy.write_buf || chip->legacy.write_buf == nand_write_buf)
606 		chip->legacy.write_buf = busw ? nand_write_buf16 : nand_write_buf;
607 	if (!chip->legacy.write_byte || chip->legacy.write_byte == nand_write_byte)
608 		chip->legacy.write_byte = busw ? nand_write_byte16 : nand_write_byte;
609 	if (!chip->legacy.read_buf || chip->legacy.read_buf == nand_read_buf)
610 		chip->legacy.read_buf = busw ? nand_read_buf16 : nand_read_buf;
611 }
612 
nand_legacy_adjust_cmdfunc(struct nand_chip * chip)613 void nand_legacy_adjust_cmdfunc(struct nand_chip *chip)
614 {
615 	struct mtd_info *mtd = nand_to_mtd(chip);
616 
617 	/* Do not replace user supplied command function! */
618 	if (mtd->writesize > 512 && chip->legacy.cmdfunc == nand_command)
619 		chip->legacy.cmdfunc = nand_command_lp;
620 }
621 
nand_legacy_check_hooks(struct nand_chip * chip)622 int nand_legacy_check_hooks(struct nand_chip *chip)
623 {
624 	/*
625 	 * ->legacy.cmdfunc() is legacy and will only be used if ->exec_op() is
626 	 * not populated.
627 	 */
628 	if (nand_has_exec_op(chip))
629 		return 0;
630 
631 	/*
632 	 * Default functions assigned for ->legacy.cmdfunc() and
633 	 * ->legacy.select_chip() both expect ->legacy.cmd_ctrl() to be
634 	 *  populated.
635 	 */
636 	if ((!chip->legacy.cmdfunc || !chip->legacy.select_chip) &&
637 	    !chip->legacy.cmd_ctrl) {
638 		pr_err("->legacy.cmd_ctrl() should be provided\n");
639 		return -EINVAL;
640 	}
641 
642 	return 0;
643 }
644