1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // Register map access API - SPI AVMM support
4 //
5 // Copyright (C) 2018-2020 Intel Corporation. All rights reserved.
6 
7 #include <linux/module.h>
8 #include <linux/regmap.h>
9 #include <linux/spi/spi.h>
10 #include <linux/swab.h>
11 
12 /*
13  * This driver implements the regmap operations for a generic SPI
14  * master to access the registers of the spi slave chip which has an
15  * Avalone bus in it.
16  *
17  * The "SPI slave to Avalon Master Bridge" (spi-avmm) IP should be integrated
18  * in the spi slave chip. The IP acts as a bridge to convert encoded streams of
19  * bytes from the host to the internal register read/write on Avalon bus. In
20  * order to issue register access requests to the slave chip, the host should
21  * send formatted bytes that conform to the transfer protocol.
22  * The transfer protocol contains 3 layers: transaction layer, packet layer
23  * and physical layer.
24  *
25  * Reference Documents could be found at:
26  * https://www.intel.com/content/www/us/en/programmable/documentation/sfo1400787952932.html
27  *
28  * Chapter "SPI Slave/JTAG to Avalon Master Bridge Cores" is a general
29  * introduction to the protocol.
30  *
31  * Chapter "Avalon Packets to Transactions Converter Core" describes
32  * the transaction layer.
33  *
34  * Chapter "Avalon-ST Bytes to Packets and Packets to Bytes Converter Cores"
35  * describes the packet layer.
36  *
37  * Chapter "Avalon-ST Serial Peripheral Interface Core" describes the
38  * physical layer.
39  *
40  *
41  * When host issues a regmap read/write, the driver will transform the request
42  * to byte stream layer by layer. It formats the register addr, value and
43  * length to the transaction layer request, then converts the request to packet
44  * layer bytes stream and then to physical layer bytes stream. Finally the
45  * driver sends the formatted byte stream over SPI bus to the slave chip.
46  *
47  * The spi-avmm IP on the slave chip decodes the byte stream and initiates
48  * register read/write on its internal Avalon bus, and then encodes the
49  * response to byte stream and sends back to host.
50  *
51  * The driver receives the byte stream, reverses the 3 layers transformation,
52  * and finally gets the response value (read out data for register read,
53  * successful written size for register write).
54  */
55 
56 #define PKT_SOP			0x7a
57 #define PKT_EOP			0x7b
58 #define PKT_CHANNEL		0x7c
59 #define PKT_ESC			0x7d
60 
61 #define PHY_IDLE		0x4a
62 #define PHY_ESC			0x4d
63 
64 #define TRANS_CODE_WRITE	0x0
65 #define TRANS_CODE_SEQ_WRITE	0x4
66 #define TRANS_CODE_READ		0x10
67 #define TRANS_CODE_SEQ_READ	0x14
68 #define TRANS_CODE_NO_TRANS	0x7f
69 
70 #define SPI_AVMM_XFER_TIMEOUT	(msecs_to_jiffies(200))
71 
72 /* slave's register addr is 32 bits */
73 #define SPI_AVMM_REG_SIZE		4UL
74 /* slave's register value is 32 bits */
75 #define SPI_AVMM_VAL_SIZE		4UL
76 
77 /*
78  * max rx size could be larger. But considering the buffer consuming,
79  * it is proper that we limit 1KB xfer at max.
80  */
81 #define MAX_READ_CNT		256UL
82 #define MAX_WRITE_CNT		1UL
83 
84 struct trans_req_header {
85 	u8 code;
86 	u8 rsvd;
87 	__be16 size;
88 	__be32 addr;
89 } __packed;
90 
91 struct trans_resp_header {
92 	u8 r_code;
93 	u8 rsvd;
94 	__be16 size;
95 } __packed;
96 
97 #define TRANS_REQ_HD_SIZE	(sizeof(struct trans_req_header))
98 #define TRANS_RESP_HD_SIZE	(sizeof(struct trans_resp_header))
99 
100 /*
101  * In transaction layer,
102  * the write request format is: Transaction request header + data
103  * the read request format is: Transaction request header
104  * the write response format is: Transaction response header
105  * the read response format is: pure data, no Transaction response header
106  */
107 #define TRANS_WR_TX_SIZE(n)	(TRANS_REQ_HD_SIZE + SPI_AVMM_VAL_SIZE * (n))
108 #define TRANS_RD_TX_SIZE	TRANS_REQ_HD_SIZE
109 #define TRANS_TX_MAX		TRANS_WR_TX_SIZE(MAX_WRITE_CNT)
110 
111 #define TRANS_RD_RX_SIZE(n)	(SPI_AVMM_VAL_SIZE * (n))
112 #define TRANS_WR_RX_SIZE	TRANS_RESP_HD_SIZE
113 #define TRANS_RX_MAX		TRANS_RD_RX_SIZE(MAX_READ_CNT)
114 
115 /* tx & rx share one transaction layer buffer */
116 #define TRANS_BUF_SIZE		((TRANS_TX_MAX > TRANS_RX_MAX) ?	\
117 				 TRANS_TX_MAX : TRANS_RX_MAX)
118 
119 /*
120  * In tx phase, the host prepares all the phy layer bytes of a request in the
121  * phy buffer and sends them in a batch.
122  *
123  * The packet layer and physical layer defines several special chars for
124  * various purpose, when a transaction layer byte hits one of these special
125  * chars, it should be escaped. The escape rule is, "Escape char first,
126  * following the byte XOR'ed with 0x20".
127  *
128  * This macro defines the max possible length of the phy data. In the worst
129  * case, all transaction layer bytes need to be escaped (so the data length
130  * doubles), plus 4 special chars (SOP, CHANNEL, CHANNEL_NUM, EOP). Finally
131  * we should make sure the length is aligned to SPI BPW.
132  */
133 #define PHY_TX_MAX		ALIGN(2 * TRANS_TX_MAX + 4, 4)
134 
135 /*
136  * Unlike tx, phy rx is affected by possible PHY_IDLE bytes from slave, the max
137  * length of the rx bit stream is unpredictable. So the driver reads the words
138  * one by one, and parses each word immediately into transaction layer buffer.
139  * Only one word length of phy buffer is used for rx.
140  */
141 #define PHY_BUF_SIZE		PHY_TX_MAX
142 
143 /**
144  * struct spi_avmm_bridge - SPI slave to AVMM bus master bridge
145  *
146  * @spi: spi slave associated with this bridge.
147  * @word_len: bytes of word for spi transfer.
148  * @trans_len: length of valid data in trans_buf.
149  * @phy_len: length of valid data in phy_buf.
150  * @trans_buf: the bridge buffer for transaction layer data.
151  * @phy_buf: the bridge buffer for physical layer data.
152  * @swap_words: the word swapping cb for phy data. NULL if not needed.
153  *
154  * As a device's registers are implemented on the AVMM bus address space, it
155  * requires the driver to issue formatted requests to spi slave to AVMM bus
156  * master bridge to perform register access.
157  */
158 struct spi_avmm_bridge {
159 	struct spi_device *spi;
160 	unsigned char word_len;
161 	unsigned int trans_len;
162 	unsigned int phy_len;
163 	/* bridge buffer used in translation between protocol layers */
164 	char trans_buf[TRANS_BUF_SIZE];
165 	char phy_buf[PHY_BUF_SIZE];
166 	void (*swap_words)(void *buf, unsigned int len);
167 };
168 
br_swap_words_32(void * buf,unsigned int len)169 static void br_swap_words_32(void *buf, unsigned int len)
170 {
171 	swab32_array(buf, len / 4);
172 }
173 
174 /*
175  * Format transaction layer data in br->trans_buf according to the register
176  * access request, Store valid transaction layer data length in br->trans_len.
177  */
br_trans_tx_prepare(struct spi_avmm_bridge * br,bool is_read,u32 reg,u32 * wr_val,u32 count)178 static int br_trans_tx_prepare(struct spi_avmm_bridge *br, bool is_read, u32 reg,
179 			       u32 *wr_val, u32 count)
180 {
181 	struct trans_req_header *header;
182 	unsigned int trans_len;
183 	u8 code;
184 	__le32 *data;
185 	int i;
186 
187 	if (is_read) {
188 		if (count == 1)
189 			code = TRANS_CODE_READ;
190 		else
191 			code = TRANS_CODE_SEQ_READ;
192 	} else {
193 		if (count == 1)
194 			code = TRANS_CODE_WRITE;
195 		else
196 			code = TRANS_CODE_SEQ_WRITE;
197 	}
198 
199 	header = (struct trans_req_header *)br->trans_buf;
200 	header->code = code;
201 	header->rsvd = 0;
202 	header->size = cpu_to_be16((u16)count * SPI_AVMM_VAL_SIZE);
203 	header->addr = cpu_to_be32(reg);
204 
205 	trans_len = TRANS_REQ_HD_SIZE;
206 
207 	if (!is_read) {
208 		trans_len += SPI_AVMM_VAL_SIZE * count;
209 		if (trans_len > sizeof(br->trans_buf))
210 			return -ENOMEM;
211 
212 		data = (__le32 *)(br->trans_buf + TRANS_REQ_HD_SIZE);
213 
214 		for (i = 0; i < count; i++)
215 			*data++ = cpu_to_le32(*wr_val++);
216 	}
217 
218 	/* Store valid trans data length for next layer */
219 	br->trans_len = trans_len;
220 
221 	return 0;
222 }
223 
224 /*
225  * Convert transaction layer data (in br->trans_buf) to phy layer data, store
226  * them in br->phy_buf. Pad the phy_buf aligned with SPI's BPW. Store valid phy
227  * layer data length in br->phy_len.
228  *
229  * phy_buf len should be aligned with SPI's BPW. Spare bytes should be padded
230  * with PHY_IDLE, then the slave will just drop them.
231  *
232  * The driver will not simply pad 4a at the tail. The concern is that driver
233  * will not store MISO data during tx phase, if the driver pads 4a at the tail,
234  * it is possible that if the slave is fast enough to response at the padding
235  * time. As a result these rx bytes are lost. In the following case, 7a,7c,00
236  * will lost.
237  * MOSI ...|7a|7c|00|10| |00|00|04|02| |4b|7d|5a|7b| |40|4a|4a|4a| |XX|XX|...
238  * MISO ...|4a|4a|4a|4a| |4a|4a|4a|4a| |4a|4a|4a|4a| |4a|7a|7c|00| |78|56|...
239  *
240  * So the driver moves EOP and bytes after EOP to the end of the aligned size,
241  * then fill the hole with PHY_IDLE. As following:
242  * before pad ...|7a|7c|00|10| |00|00|04|02| |4b|7d|5a|7b| |40|
243  * after pad  ...|7a|7c|00|10| |00|00|04|02| |4b|7d|5a|4a| |4a|4a|7b|40|
244  * Then if the slave will not get the entire packet before the tx phase is
245  * over, it can't responsed to anything either.
246  */
br_pkt_phy_tx_prepare(struct spi_avmm_bridge * br)247 static int br_pkt_phy_tx_prepare(struct spi_avmm_bridge *br)
248 {
249 	char *tb, *tb_end, *pb, *pb_limit, *pb_eop = NULL;
250 	unsigned int aligned_phy_len, move_size;
251 	bool need_esc = false;
252 
253 	tb = br->trans_buf;
254 	tb_end = tb + br->trans_len;
255 	pb = br->phy_buf;
256 	pb_limit = pb + ARRAY_SIZE(br->phy_buf);
257 
258 	*pb++ = PKT_SOP;
259 
260 	/*
261 	 * The driver doesn't support multiple channels so the channel number
262 	 * is always 0.
263 	 */
264 	*pb++ = PKT_CHANNEL;
265 	*pb++ = 0x0;
266 
267 	for (; pb < pb_limit && tb < tb_end; pb++) {
268 		if (need_esc) {
269 			*pb = *tb++ ^ 0x20;
270 			need_esc = false;
271 			continue;
272 		}
273 
274 		/* EOP should be inserted before the last valid char */
275 		if (tb == tb_end - 1 && !pb_eop) {
276 			*pb = PKT_EOP;
277 			pb_eop = pb;
278 			continue;
279 		}
280 
281 		/*
282 		 * insert an ESCAPE char if the data value equals any special
283 		 * char.
284 		 */
285 		switch (*tb) {
286 		case PKT_SOP:
287 		case PKT_EOP:
288 		case PKT_CHANNEL:
289 		case PKT_ESC:
290 			*pb = PKT_ESC;
291 			need_esc = true;
292 			break;
293 		case PHY_IDLE:
294 		case PHY_ESC:
295 			*pb = PHY_ESC;
296 			need_esc = true;
297 			break;
298 		default:
299 			*pb = *tb++;
300 			break;
301 		}
302 	}
303 
304 	/* The phy buffer is used out but transaction layer data remains */
305 	if (tb < tb_end)
306 		return -ENOMEM;
307 
308 	/* Store valid phy data length for spi transfer */
309 	br->phy_len = pb - br->phy_buf;
310 
311 	if (br->word_len == 1)
312 		return 0;
313 
314 	/* Do phy buf padding if word_len > 1 byte. */
315 	aligned_phy_len = ALIGN(br->phy_len, br->word_len);
316 	if (aligned_phy_len > sizeof(br->phy_buf))
317 		return -ENOMEM;
318 
319 	if (aligned_phy_len == br->phy_len)
320 		return 0;
321 
322 	/* move EOP and bytes after EOP to the end of aligned size */
323 	move_size = pb - pb_eop;
324 	memmove(&br->phy_buf[aligned_phy_len - move_size], pb_eop, move_size);
325 
326 	/* fill the hole with PHY_IDLEs */
327 	memset(pb_eop, PHY_IDLE, aligned_phy_len - br->phy_len);
328 
329 	/* update the phy data length */
330 	br->phy_len = aligned_phy_len;
331 
332 	return 0;
333 }
334 
335 /*
336  * In tx phase, the slave only returns PHY_IDLE (0x4a). So the driver will
337  * ignore rx in tx phase.
338  */
br_do_tx(struct spi_avmm_bridge * br)339 static int br_do_tx(struct spi_avmm_bridge *br)
340 {
341 	/* reorder words for spi transfer */
342 	if (br->swap_words)
343 		br->swap_words(br->phy_buf, br->phy_len);
344 
345 	/* send all data in phy_buf  */
346 	return spi_write(br->spi, br->phy_buf, br->phy_len);
347 }
348 
349 /*
350  * This function read the rx byte stream from SPI word by word and convert
351  * them to transaction layer data in br->trans_buf. It also stores the length
352  * of rx transaction layer data in br->trans_len
353  *
354  * The slave may send an unknown number of PHY_IDLEs in rx phase, so we cannot
355  * prepare a fixed length buffer to receive all of the rx data in a batch. We
356  * have to read word by word and convert them to transaction layer data at
357  * once.
358  */
br_do_rx_and_pkt_phy_parse(struct spi_avmm_bridge * br)359 static int br_do_rx_and_pkt_phy_parse(struct spi_avmm_bridge *br)
360 {
361 	bool eop_found = false, channel_found = false, esc_found = false;
362 	bool valid_word = false, last_try = false;
363 	struct device *dev = &br->spi->dev;
364 	char *pb, *tb_limit, *tb = NULL;
365 	unsigned long poll_timeout;
366 	int ret, i;
367 
368 	tb_limit = br->trans_buf + ARRAY_SIZE(br->trans_buf);
369 	pb = br->phy_buf;
370 	poll_timeout = jiffies + SPI_AVMM_XFER_TIMEOUT;
371 	while (tb < tb_limit) {
372 		ret = spi_read(br->spi, pb, br->word_len);
373 		if (ret)
374 			return ret;
375 
376 		/* reorder the word back */
377 		if (br->swap_words)
378 			br->swap_words(pb, br->word_len);
379 
380 		valid_word = false;
381 		for (i = 0; i < br->word_len; i++) {
382 			/* drop everything before first SOP */
383 			if (!tb && pb[i] != PKT_SOP)
384 				continue;
385 
386 			/* drop PHY_IDLE */
387 			if (pb[i] == PHY_IDLE)
388 				continue;
389 
390 			valid_word = true;
391 
392 			/*
393 			 * We don't support multiple channels, so error out if
394 			 * a non-zero channel number is found.
395 			 */
396 			if (channel_found) {
397 				if (pb[i] != 0) {
398 					dev_err(dev, "%s channel num != 0\n",
399 						__func__);
400 					return -EFAULT;
401 				}
402 
403 				channel_found = false;
404 				continue;
405 			}
406 
407 			switch (pb[i]) {
408 			case PKT_SOP:
409 				/*
410 				 * reset the parsing if a second SOP appears.
411 				 */
412 				tb = br->trans_buf;
413 				eop_found = false;
414 				channel_found = false;
415 				esc_found = false;
416 				break;
417 			case PKT_EOP:
418 				/*
419 				 * No special char is expected after ESC char.
420 				 * No special char (except ESC & PHY_IDLE) is
421 				 * expected after EOP char.
422 				 *
423 				 * The special chars are all dropped.
424 				 */
425 				if (esc_found || eop_found)
426 					return -EFAULT;
427 
428 				eop_found = true;
429 				break;
430 			case PKT_CHANNEL:
431 				if (esc_found || eop_found)
432 					return -EFAULT;
433 
434 				channel_found = true;
435 				break;
436 			case PKT_ESC:
437 			case PHY_ESC:
438 				if (esc_found)
439 					return -EFAULT;
440 
441 				esc_found = true;
442 				break;
443 			default:
444 				/* Record the normal byte in trans_buf. */
445 				if (esc_found) {
446 					*tb++ = pb[i] ^ 0x20;
447 					esc_found = false;
448 				} else {
449 					*tb++ = pb[i];
450 				}
451 
452 				/*
453 				 * We get the last normal byte after EOP, it is
454 				 * time we finish. Normally the function should
455 				 * return here.
456 				 */
457 				if (eop_found) {
458 					br->trans_len = tb - br->trans_buf;
459 					return 0;
460 				}
461 			}
462 		}
463 
464 		if (valid_word) {
465 			/* update poll timeout when we get valid word */
466 			poll_timeout = jiffies + SPI_AVMM_XFER_TIMEOUT;
467 			last_try = false;
468 		} else {
469 			/*
470 			 * We timeout when rx keeps invalid for some time. But
471 			 * it is possible we are scheduled out for long time
472 			 * after a spi_read. So when we are scheduled in, a SW
473 			 * timeout happens. But actually HW may have worked fine and
474 			 * has been ready long time ago. So we need to do an extra
475 			 * read, if we get a valid word then we could continue rx,
476 			 * otherwise real a HW issue happens.
477 			 */
478 			if (last_try)
479 				return -ETIMEDOUT;
480 
481 			if (time_after(jiffies, poll_timeout))
482 				last_try = true;
483 		}
484 	}
485 
486 	/*
487 	 * We have used out all transfer layer buffer but cannot find the end
488 	 * of the byte stream.
489 	 */
490 	dev_err(dev, "%s transfer buffer is full but rx doesn't end\n",
491 		__func__);
492 
493 	return -EFAULT;
494 }
495 
496 /*
497  * For read transactions, the avmm bus will directly return register values
498  * without transaction response header.
499  */
br_rd_trans_rx_parse(struct spi_avmm_bridge * br,u32 * val,unsigned int expected_count)500 static int br_rd_trans_rx_parse(struct spi_avmm_bridge *br,
501 				u32 *val, unsigned int expected_count)
502 {
503 	unsigned int i, trans_len = br->trans_len;
504 	__le32 *data;
505 
506 	if (expected_count * SPI_AVMM_VAL_SIZE != trans_len)
507 		return -EFAULT;
508 
509 	data = (__le32 *)br->trans_buf;
510 	for (i = 0; i < expected_count; i++)
511 		*val++ = le32_to_cpu(*data++);
512 
513 	return 0;
514 }
515 
516 /*
517  * For write transactions, the slave will return a transaction response
518  * header.
519  */
br_wr_trans_rx_parse(struct spi_avmm_bridge * br,unsigned int expected_count)520 static int br_wr_trans_rx_parse(struct spi_avmm_bridge *br,
521 				unsigned int expected_count)
522 {
523 	unsigned int trans_len = br->trans_len;
524 	struct trans_resp_header *resp;
525 	u8 code;
526 	u16 val_len;
527 
528 	if (trans_len != TRANS_RESP_HD_SIZE)
529 		return -EFAULT;
530 
531 	resp = (struct trans_resp_header *)br->trans_buf;
532 
533 	code = resp->r_code ^ 0x80;
534 	val_len = be16_to_cpu(resp->size);
535 	if (!val_len || val_len != expected_count * SPI_AVMM_VAL_SIZE)
536 		return -EFAULT;
537 
538 	/* error out if the trans code doesn't align with the val size */
539 	if ((val_len == SPI_AVMM_VAL_SIZE && code != TRANS_CODE_WRITE) ||
540 	    (val_len > SPI_AVMM_VAL_SIZE && code != TRANS_CODE_SEQ_WRITE))
541 		return -EFAULT;
542 
543 	return 0;
544 }
545 
do_reg_access(void * context,bool is_read,unsigned int reg,unsigned int * value,unsigned int count)546 static int do_reg_access(void *context, bool is_read, unsigned int reg,
547 			 unsigned int *value, unsigned int count)
548 {
549 	struct spi_avmm_bridge *br = context;
550 	int ret;
551 
552 	/* invalidate bridge buffers first */
553 	br->trans_len = 0;
554 	br->phy_len = 0;
555 
556 	ret = br_trans_tx_prepare(br, is_read, reg, value, count);
557 	if (ret)
558 		return ret;
559 
560 	ret = br_pkt_phy_tx_prepare(br);
561 	if (ret)
562 		return ret;
563 
564 	ret = br_do_tx(br);
565 	if (ret)
566 		return ret;
567 
568 	ret = br_do_rx_and_pkt_phy_parse(br);
569 	if (ret)
570 		return ret;
571 
572 	if (is_read)
573 		return br_rd_trans_rx_parse(br, value, count);
574 	else
575 		return br_wr_trans_rx_parse(br, count);
576 }
577 
regmap_spi_avmm_gather_write(void * context,const void * reg_buf,size_t reg_len,const void * val_buf,size_t val_len)578 static int regmap_spi_avmm_gather_write(void *context,
579 					const void *reg_buf, size_t reg_len,
580 					const void *val_buf, size_t val_len)
581 {
582 	if (reg_len != SPI_AVMM_REG_SIZE)
583 		return -EINVAL;
584 
585 	if (!IS_ALIGNED(val_len, SPI_AVMM_VAL_SIZE))
586 		return -EINVAL;
587 
588 	return do_reg_access(context, false, *(u32 *)reg_buf, (u32 *)val_buf,
589 			     val_len / SPI_AVMM_VAL_SIZE);
590 }
591 
regmap_spi_avmm_write(void * context,const void * data,size_t bytes)592 static int regmap_spi_avmm_write(void *context, const void *data, size_t bytes)
593 {
594 	if (bytes < SPI_AVMM_REG_SIZE + SPI_AVMM_VAL_SIZE)
595 		return -EINVAL;
596 
597 	return regmap_spi_avmm_gather_write(context, data, SPI_AVMM_REG_SIZE,
598 					    data + SPI_AVMM_REG_SIZE,
599 					    bytes - SPI_AVMM_REG_SIZE);
600 }
601 
regmap_spi_avmm_read(void * context,const void * reg_buf,size_t reg_len,void * val_buf,size_t val_len)602 static int regmap_spi_avmm_read(void *context,
603 				const void *reg_buf, size_t reg_len,
604 				void *val_buf, size_t val_len)
605 {
606 	if (reg_len != SPI_AVMM_REG_SIZE)
607 		return -EINVAL;
608 
609 	if (!IS_ALIGNED(val_len, SPI_AVMM_VAL_SIZE))
610 		return -EINVAL;
611 
612 	return do_reg_access(context, true, *(u32 *)reg_buf, val_buf,
613 			     (val_len / SPI_AVMM_VAL_SIZE));
614 }
615 
616 static struct spi_avmm_bridge *
spi_avmm_bridge_ctx_gen(struct spi_device * spi)617 spi_avmm_bridge_ctx_gen(struct spi_device *spi)
618 {
619 	struct spi_avmm_bridge *br;
620 
621 	if (!spi)
622 		return ERR_PTR(-ENODEV);
623 
624 	/* Only support BPW == 8 or 32 now. Try 32 BPW first. */
625 	spi->mode = SPI_MODE_1;
626 	spi->bits_per_word = 32;
627 	if (spi_setup(spi)) {
628 		spi->bits_per_word = 8;
629 		if (spi_setup(spi))
630 			return ERR_PTR(-EINVAL);
631 	}
632 
633 	br = kzalloc(sizeof(*br), GFP_KERNEL);
634 	if (!br)
635 		return ERR_PTR(-ENOMEM);
636 
637 	br->spi = spi;
638 	br->word_len = spi->bits_per_word / 8;
639 	if (br->word_len == 4) {
640 		/*
641 		 * The protocol requires little endian byte order but MSB
642 		 * first. So driver needs to swap the byte order word by word
643 		 * if word length > 1.
644 		 */
645 		br->swap_words = br_swap_words_32;
646 	}
647 
648 	return br;
649 }
650 
spi_avmm_bridge_ctx_free(void * context)651 static void spi_avmm_bridge_ctx_free(void *context)
652 {
653 	kfree(context);
654 }
655 
656 static const struct regmap_bus regmap_spi_avmm_bus = {
657 	.write = regmap_spi_avmm_write,
658 	.gather_write = regmap_spi_avmm_gather_write,
659 	.read = regmap_spi_avmm_read,
660 	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
661 	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
662 	.max_raw_read = SPI_AVMM_VAL_SIZE * MAX_READ_CNT,
663 	.max_raw_write = SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT,
664 	.free_context = spi_avmm_bridge_ctx_free,
665 };
666 
__regmap_init_spi_avmm(struct spi_device * spi,const struct regmap_config * config,struct lock_class_key * lock_key,const char * lock_name)667 struct regmap *__regmap_init_spi_avmm(struct spi_device *spi,
668 				      const struct regmap_config *config,
669 				      struct lock_class_key *lock_key,
670 				      const char *lock_name)
671 {
672 	struct spi_avmm_bridge *bridge;
673 	struct regmap *map;
674 
675 	bridge = spi_avmm_bridge_ctx_gen(spi);
676 	if (IS_ERR(bridge))
677 		return ERR_CAST(bridge);
678 
679 	map = __regmap_init(&spi->dev, &regmap_spi_avmm_bus,
680 			    bridge, config, lock_key, lock_name);
681 	if (IS_ERR(map)) {
682 		spi_avmm_bridge_ctx_free(bridge);
683 		return ERR_CAST(map);
684 	}
685 
686 	return map;
687 }
688 EXPORT_SYMBOL_GPL(__regmap_init_spi_avmm);
689 
__devm_regmap_init_spi_avmm(struct spi_device * spi,const struct regmap_config * config,struct lock_class_key * lock_key,const char * lock_name)690 struct regmap *__devm_regmap_init_spi_avmm(struct spi_device *spi,
691 					   const struct regmap_config *config,
692 					   struct lock_class_key *lock_key,
693 					   const char *lock_name)
694 {
695 	struct spi_avmm_bridge *bridge;
696 	struct regmap *map;
697 
698 	bridge = spi_avmm_bridge_ctx_gen(spi);
699 	if (IS_ERR(bridge))
700 		return ERR_CAST(bridge);
701 
702 	map = __devm_regmap_init(&spi->dev, &regmap_spi_avmm_bus,
703 				 bridge, config, lock_key, lock_name);
704 	if (IS_ERR(map)) {
705 		spi_avmm_bridge_ctx_free(bridge);
706 		return ERR_CAST(map);
707 	}
708 
709 	return map;
710 }
711 EXPORT_SYMBOL_GPL(__devm_regmap_init_spi_avmm);
712 
713 MODULE_LICENSE("GPL v2");
714