xref: /linux/drivers/mfd/rave-sp.c (revision 791d3ef2e11100449837dc0b6fe884e60ca3a484)
1 // SPDX-License-Identifier: GPL-2.0+
2 
3 /*
4  * Multifunction core driver for Zodiac Inflight Innovations RAVE
5  * Supervisory Processor(SP) MCU that is connected via dedicated UART
6  * port
7  *
8  * Copyright (C) 2017 Zodiac Inflight Innovations
9  */
10 
11 #include <linux/atomic.h>
12 #include <linux/crc-ccitt.h>
13 #include <linux/delay.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/kernel.h>
18 #include <linux/mfd/rave-sp.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/of_device.h>
22 #include <linux/sched.h>
23 #include <linux/serdev.h>
24 #include <asm/unaligned.h>
25 
26 /*
27  * UART protocol using following entities:
28  *  - message to MCU => ACK response
29  *  - event from MCU => event ACK
30  *
31  * Frame structure:
32  * <STX> <DATA> <CHECKSUM> <ETX>
33  * Where:
34  * - STX - is start of transmission character
35  * - ETX - end of transmission
36  * - DATA - payload
37  * - CHECKSUM - checksum calculated on <DATA>
38  *
39  * If <DATA> or <CHECKSUM> contain one of control characters, then it is
40  * escaped using <DLE> control code. Added <DLE> does not participate in
41  * checksum calculation.
42  */
43 #define RAVE_SP_STX			0x02
44 #define RAVE_SP_ETX			0x03
45 #define RAVE_SP_DLE			0x10
46 
47 #define RAVE_SP_MAX_DATA_SIZE		64
48 #define RAVE_SP_CHECKSUM_8B2C		1
49 #define RAVE_SP_CHECKSUM_CCITT		2
50 #define RAVE_SP_CHECKSUM_SIZE		RAVE_SP_CHECKSUM_CCITT
51 /*
52  * We don't store STX, ETX and unescaped bytes, so Rx is only
53  * DATA + CSUM
54  */
55 #define RAVE_SP_RX_BUFFER_SIZE				\
56 	(RAVE_SP_MAX_DATA_SIZE + RAVE_SP_CHECKSUM_SIZE)
57 
58 #define RAVE_SP_STX_ETX_SIZE		2
59 /*
60  * For Tx we have to have space for everything, STX, EXT and
61  * potentially stuffed DATA + CSUM data + csum
62  */
63 #define RAVE_SP_TX_BUFFER_SIZE				\
64 	(RAVE_SP_STX_ETX_SIZE + 2 * RAVE_SP_RX_BUFFER_SIZE)
65 
66 #define RAVE_SP_BOOT_SOURCE_GET		0
67 #define RAVE_SP_BOOT_SOURCE_SET		1
68 
69 #define RAVE_SP_RDU2_BOARD_TYPE_RMB	0
70 #define RAVE_SP_RDU2_BOARD_TYPE_DEB	1
71 
72 #define RAVE_SP_BOOT_SOURCE_SD		0
73 #define RAVE_SP_BOOT_SOURCE_EMMC	1
74 #define RAVE_SP_BOOT_SOURCE_NOR		2
75 
76 /**
77  * enum rave_sp_deframer_state - Possible state for de-framer
78  *
79  * @RAVE_SP_EXPECT_SOF:		 Scanning input for start-of-frame marker
80  * @RAVE_SP_EXPECT_DATA:	 Got start of frame marker, collecting frame
81  * @RAVE_SP_EXPECT_ESCAPED_DATA: Got escape character, collecting escaped byte
82  */
83 enum rave_sp_deframer_state {
84 	RAVE_SP_EXPECT_SOF,
85 	RAVE_SP_EXPECT_DATA,
86 	RAVE_SP_EXPECT_ESCAPED_DATA,
87 };
88 
89 /**
90  * struct rave_sp_deframer - Device protocol deframer
91  *
92  * @state:  Current state of the deframer
93  * @data:   Buffer used to collect deframed data
94  * @length: Number of bytes de-framed so far
95  */
96 struct rave_sp_deframer {
97 	enum rave_sp_deframer_state state;
98 	unsigned char data[RAVE_SP_RX_BUFFER_SIZE];
99 	size_t length;
100 };
101 
102 /**
103  * struct rave_sp_reply - Reply as per RAVE device protocol
104  *
105  * @length:	Expected reply length
106  * @data:	Buffer to store reply payload in
107  * @code:	Expected reply code
108  * @ackid:	Expected reply ACK ID
109  * @completion: Successful reply reception completion
110  */
111 struct rave_sp_reply {
112 	size_t length;
113 	void  *data;
114 	u8     code;
115 	u8     ackid;
116 	struct completion received;
117 };
118 
119 /**
120  * struct rave_sp_checksum - Variant specific checksum implementation details
121  *
122  * @length:	Caculated checksum length
123  * @subroutine:	Utilized checksum algorithm implementation
124  */
125 struct rave_sp_checksum {
126 	size_t length;
127 	void (*subroutine)(const u8 *, size_t, u8 *);
128 };
129 
130 /**
131  * struct rave_sp_variant_cmds - Variant specific command routines
132  *
133  * @translate:	Generic to variant specific command mapping routine
134  *
135  */
136 struct rave_sp_variant_cmds {
137 	int (*translate)(enum rave_sp_command);
138 };
139 
140 /**
141  * struct rave_sp_variant - RAVE supervisory processor core variant
142  *
143  * @checksum:	Variant specific checksum implementation
144  * @cmd:	Variant specific command pointer table
145  *
146  */
147 struct rave_sp_variant {
148 	const struct rave_sp_checksum *checksum;
149 	struct rave_sp_variant_cmds cmd;
150 };
151 
152 /**
153  * struct rave_sp - RAVE supervisory processor core
154  *
155  * @serdev:			Pointer to underlying serdev
156  * @deframer:			Stored state of the protocol deframer
157  * @ackid:			ACK ID used in last reply sent to the device
158  * @bus_lock:			Lock to serialize access to the device
159  * @reply_lock:			Lock protecting @reply
160  * @reply:			Pointer to memory to store reply payload
161  *
162  * @variant:			Device variant specific information
163  * @event_notifier_list:	Input event notification chain
164  *
165  * @part_number_firmware:	Firmware version
166  * @part_number_bootloader:	Bootloader version
167  */
168 struct rave_sp {
169 	struct serdev_device *serdev;
170 	struct rave_sp_deframer deframer;
171 	atomic_t ackid;
172 	struct mutex bus_lock;
173 	struct mutex reply_lock;
174 	struct rave_sp_reply *reply;
175 
176 	const struct rave_sp_variant *variant;
177 	struct blocking_notifier_head event_notifier_list;
178 
179 	const char *part_number_firmware;
180 	const char *part_number_bootloader;
181 };
182 
183 struct rave_sp_version {
184 	u8     hardware;
185 	__le16 major;
186 	u8     minor;
187 	u8     letter[2];
188 } __packed;
189 
190 struct rave_sp_status {
191 	struct rave_sp_version bootloader_version;
192 	struct rave_sp_version firmware_version;
193 	u16 rdu_eeprom_flag;
194 	u16 dds_eeprom_flag;
195 	u8  pic_flag;
196 	u8  orientation;
197 	u32 etc;
198 	s16 temp[2];
199 	u8  backlight_current[3];
200 	u8  dip_switch;
201 	u8  host_interrupt;
202 	u16 voltage_28;
203 	u8  i2c_device_status;
204 	u8  power_status;
205 	u8  general_status;
206 	u8  deprecated1;
207 	u8  power_led_status;
208 	u8  deprecated2;
209 	u8  periph_power_shutoff;
210 } __packed;
211 
212 static bool rave_sp_id_is_event(u8 code)
213 {
214 	return (code & 0xF0) == RAVE_SP_EVNT_BASE;
215 }
216 
217 static void rave_sp_unregister_event_notifier(struct device *dev, void *res)
218 {
219 	struct rave_sp *sp = dev_get_drvdata(dev->parent);
220 	struct notifier_block *nb = *(struct notifier_block **)res;
221 	struct blocking_notifier_head *bnh = &sp->event_notifier_list;
222 
223 	WARN_ON(blocking_notifier_chain_unregister(bnh, nb));
224 }
225 
226 int devm_rave_sp_register_event_notifier(struct device *dev,
227 					 struct notifier_block *nb)
228 {
229 	struct rave_sp *sp = dev_get_drvdata(dev->parent);
230 	struct notifier_block **rcnb;
231 	int ret;
232 
233 	rcnb = devres_alloc(rave_sp_unregister_event_notifier,
234 			    sizeof(*rcnb), GFP_KERNEL);
235 	if (!rcnb)
236 		return -ENOMEM;
237 
238 	ret = blocking_notifier_chain_register(&sp->event_notifier_list, nb);
239 	if (!ret) {
240 		*rcnb = nb;
241 		devres_add(dev, rcnb);
242 	} else {
243 		devres_free(rcnb);
244 	}
245 
246 	return ret;
247 }
248 EXPORT_SYMBOL_GPL(devm_rave_sp_register_event_notifier);
249 
250 static void csum_8b2c(const u8 *buf, size_t size, u8 *crc)
251 {
252 	*crc = *buf++;
253 	size--;
254 
255 	while (size--)
256 		*crc += *buf++;
257 
258 	*crc = 1 + ~(*crc);
259 }
260 
261 static void csum_ccitt(const u8 *buf, size_t size, u8 *crc)
262 {
263 	const u16 calculated = crc_ccitt_false(0xffff, buf, size);
264 
265 	/*
266 	 * While the rest of the wire protocol is little-endian,
267 	 * CCITT-16 CRC in RDU2 device is sent out in big-endian order.
268 	 */
269 	put_unaligned_be16(calculated, crc);
270 }
271 
272 static void *stuff(unsigned char *dest, const unsigned char *src, size_t n)
273 {
274 	while (n--) {
275 		const unsigned char byte = *src++;
276 
277 		switch (byte) {
278 		case RAVE_SP_STX:
279 		case RAVE_SP_ETX:
280 		case RAVE_SP_DLE:
281 			*dest++ = RAVE_SP_DLE;
282 			/* FALLTHROUGH */
283 		default:
284 			*dest++ = byte;
285 		}
286 	}
287 
288 	return dest;
289 }
290 
291 static int rave_sp_write(struct rave_sp *sp, const u8 *data, u8 data_size)
292 {
293 	const size_t checksum_length = sp->variant->checksum->length;
294 	unsigned char frame[RAVE_SP_TX_BUFFER_SIZE];
295 	unsigned char crc[RAVE_SP_CHECKSUM_SIZE];
296 	unsigned char *dest = frame;
297 	size_t length;
298 
299 	if (WARN_ON(checksum_length > sizeof(crc)))
300 		return -ENOMEM;
301 
302 	if (WARN_ON(data_size > sizeof(frame)))
303 		return -ENOMEM;
304 
305 	sp->variant->checksum->subroutine(data, data_size, crc);
306 
307 	*dest++ = RAVE_SP_STX;
308 	dest = stuff(dest, data, data_size);
309 	dest = stuff(dest, crc, checksum_length);
310 	*dest++ = RAVE_SP_ETX;
311 
312 	length = dest - frame;
313 
314 	print_hex_dump_debug("rave-sp tx: ", DUMP_PREFIX_NONE,
315 			     16, 1, frame, length, false);
316 
317 	return serdev_device_write(sp->serdev, frame, length, HZ);
318 }
319 
320 static u8 rave_sp_reply_code(u8 command)
321 {
322 	/*
323 	 * There isn't a single rule that describes command code ->
324 	 * ACK code transformation, but, going through various
325 	 * versions of ICDs, there appear to be three distinct groups
326 	 * that can be described by simple transformation.
327 	 */
328 	switch (command) {
329 	case 0xA0 ... 0xBE:
330 		/*
331 		 * Commands implemented by firmware found in RDU1 and
332 		 * older devices all seem to obey the following rule
333 		 */
334 		return command + 0x20;
335 	case 0xE0 ... 0xEF:
336 		/*
337 		 * Events emitted by all versions of the firmare use
338 		 * least significant bit to get an ACK code
339 		 */
340 		return command | 0x01;
341 	default:
342 		/*
343 		 * Commands implemented by firmware found in RDU2 are
344 		 * similar to "old" commands, but they use slightly
345 		 * different offset
346 		 */
347 		return command + 0x40;
348 	}
349 }
350 
351 int rave_sp_exec(struct rave_sp *sp,
352 		 void *__data,  size_t data_size,
353 		 void *reply_data, size_t reply_data_size)
354 {
355 	struct rave_sp_reply reply = {
356 		.data     = reply_data,
357 		.length   = reply_data_size,
358 		.received = COMPLETION_INITIALIZER_ONSTACK(reply.received),
359 	};
360 	unsigned char *data = __data;
361 	int command, ret = 0;
362 	u8 ackid;
363 
364 	command = sp->variant->cmd.translate(data[0]);
365 	if (command < 0)
366 		return command;
367 
368 	ackid       = atomic_inc_return(&sp->ackid);
369 	reply.ackid = ackid;
370 	reply.code  = rave_sp_reply_code((u8)command),
371 
372 	mutex_lock(&sp->bus_lock);
373 
374 	mutex_lock(&sp->reply_lock);
375 	sp->reply = &reply;
376 	mutex_unlock(&sp->reply_lock);
377 
378 	data[0] = command;
379 	data[1] = ackid;
380 
381 	rave_sp_write(sp, data, data_size);
382 
383 	if (!wait_for_completion_timeout(&reply.received, HZ)) {
384 		dev_err(&sp->serdev->dev, "Command timeout\n");
385 		ret = -ETIMEDOUT;
386 
387 		mutex_lock(&sp->reply_lock);
388 		sp->reply = NULL;
389 		mutex_unlock(&sp->reply_lock);
390 	}
391 
392 	mutex_unlock(&sp->bus_lock);
393 	return ret;
394 }
395 EXPORT_SYMBOL_GPL(rave_sp_exec);
396 
397 static void rave_sp_receive_event(struct rave_sp *sp,
398 				  const unsigned char *data, size_t length)
399 {
400 	u8 cmd[] = {
401 		[0] = rave_sp_reply_code(data[0]),
402 		[1] = data[1],
403 	};
404 
405 	rave_sp_write(sp, cmd, sizeof(cmd));
406 
407 	blocking_notifier_call_chain(&sp->event_notifier_list,
408 				     rave_sp_action_pack(data[0], data[2]),
409 				     NULL);
410 }
411 
412 static void rave_sp_receive_reply(struct rave_sp *sp,
413 				  const unsigned char *data, size_t length)
414 {
415 	struct device *dev = &sp->serdev->dev;
416 	struct rave_sp_reply *reply;
417 	const  size_t payload_length = length - 2;
418 
419 	mutex_lock(&sp->reply_lock);
420 	reply = sp->reply;
421 
422 	if (reply) {
423 		if (reply->code == data[0] && reply->ackid == data[1] &&
424 		    payload_length >= reply->length) {
425 			/*
426 			 * We are relying on memcpy(dst, src, 0) to be a no-op
427 			 * when handling commands that have a no-payload reply
428 			 */
429 			memcpy(reply->data, &data[2], reply->length);
430 			complete(&reply->received);
431 			sp->reply = NULL;
432 		} else {
433 			dev_err(dev, "Ignoring incorrect reply\n");
434 			dev_dbg(dev, "Code:   expected = 0x%08x received = 0x%08x\n",
435 				reply->code, data[0]);
436 			dev_dbg(dev, "ACK ID: expected = 0x%08x received = 0x%08x\n",
437 				reply->ackid, data[1]);
438 			dev_dbg(dev, "Length: expected = %zu received = %zu\n",
439 				reply->length, payload_length);
440 		}
441 	}
442 
443 	mutex_unlock(&sp->reply_lock);
444 }
445 
446 static void rave_sp_receive_frame(struct rave_sp *sp,
447 				  const unsigned char *data,
448 				  size_t length)
449 {
450 	const size_t checksum_length = sp->variant->checksum->length;
451 	const size_t payload_length  = length - checksum_length;
452 	const u8 *crc_reported       = &data[payload_length];
453 	struct device *dev           = &sp->serdev->dev;
454 	u8 crc_calculated[RAVE_SP_CHECKSUM_SIZE];
455 
456 	if (unlikely(checksum_length > sizeof(crc_calculated))) {
457 		dev_warn(dev, "Checksum too long, dropping\n");
458 		return;
459 	}
460 
461 	print_hex_dump_debug("rave-sp rx: ", DUMP_PREFIX_NONE,
462 			     16, 1, data, length, false);
463 
464 	if (unlikely(length <= checksum_length)) {
465 		dev_warn(dev, "Dropping short frame\n");
466 		return;
467 	}
468 
469 	sp->variant->checksum->subroutine(data, payload_length,
470 					  crc_calculated);
471 
472 	if (memcmp(crc_calculated, crc_reported, checksum_length)) {
473 		dev_warn(dev, "Dropping bad frame\n");
474 		return;
475 	}
476 
477 	if (rave_sp_id_is_event(data[0]))
478 		rave_sp_receive_event(sp, data, length);
479 	else
480 		rave_sp_receive_reply(sp, data, length);
481 }
482 
483 static int rave_sp_receive_buf(struct serdev_device *serdev,
484 			       const unsigned char *buf, size_t size)
485 {
486 	struct device *dev = &serdev->dev;
487 	struct rave_sp *sp = dev_get_drvdata(dev);
488 	struct rave_sp_deframer *deframer = &sp->deframer;
489 	const unsigned char *src = buf;
490 	const unsigned char *end = buf + size;
491 
492 	while (src < end) {
493 		const unsigned char byte = *src++;
494 
495 		switch (deframer->state) {
496 		case RAVE_SP_EXPECT_SOF:
497 			if (byte == RAVE_SP_STX)
498 				deframer->state = RAVE_SP_EXPECT_DATA;
499 			break;
500 
501 		case RAVE_SP_EXPECT_DATA:
502 			/*
503 			 * Treat special byte values first
504 			 */
505 			switch (byte) {
506 			case RAVE_SP_ETX:
507 				rave_sp_receive_frame(sp,
508 						      deframer->data,
509 						      deframer->length);
510 				/*
511 				 * Once we extracted a complete frame
512 				 * out of a stream, we call it done
513 				 * and proceed to bailing out while
514 				 * resetting the framer to initial
515 				 * state, regardless if we've consumed
516 				 * all of the stream or not.
517 				 */
518 				goto reset_framer;
519 			case RAVE_SP_STX:
520 				dev_warn(dev, "Bad frame: STX before ETX\n");
521 				/*
522 				 * If we encounter second "start of
523 				 * the frame" marker before seeing
524 				 * corresponding "end of frame", we
525 				 * reset the framer and ignore both:
526 				 * frame started by first SOF and
527 				 * frame started by current SOF.
528 				 *
529 				 * NOTE: The above means that only the
530 				 * frame started by third SOF, sent
531 				 * after this one will have a chance
532 				 * to get throught.
533 				 */
534 				goto reset_framer;
535 			case RAVE_SP_DLE:
536 				deframer->state = RAVE_SP_EXPECT_ESCAPED_DATA;
537 				/*
538 				 * If we encounter escape sequence we
539 				 * need to skip it and collect the
540 				 * byte that follows. We do it by
541 				 * forcing the next iteration of the
542 				 * encompassing while loop.
543 				 */
544 				continue;
545 			}
546 			/*
547 			 * For the rest of the bytes, that are not
548 			 * speical snoflakes, we do the same thing
549 			 * that we do to escaped data - collect it in
550 			 * deframer buffer
551 			 */
552 
553 			/* FALLTHROUGH */
554 
555 		case RAVE_SP_EXPECT_ESCAPED_DATA:
556 			if (deframer->length == sizeof(deframer->data)) {
557 				dev_warn(dev, "Bad frame: Too long\n");
558 				/*
559 				 * If the amount of data we've
560 				 * accumulated for current frame so
561 				 * far starts to exceed the capacity
562 				 * of deframer's buffer, there's
563 				 * nothing else we can do but to
564 				 * discard that data and start
565 				 * assemblying a new frame again
566 				 */
567 				goto reset_framer;
568 			}
569 
570 			deframer->data[deframer->length++] = byte;
571 
572 			/*
573 			 * We've extracted out special byte, now we
574 			 * can go back to regular data collecting
575 			 */
576 			deframer->state = RAVE_SP_EXPECT_DATA;
577 			break;
578 		}
579 	}
580 
581 	/*
582 	 * The only way to get out of the above loop and end up here
583 	 * is throught consuming all of the supplied data, so here we
584 	 * report that we processed it all.
585 	 */
586 	return size;
587 
588 reset_framer:
589 	/*
590 	 * NOTE: A number of codepaths that will drop us here will do
591 	 * so before consuming all 'size' bytes of the data passed by
592 	 * serdev layer. We rely on the fact that serdev layer will
593 	 * re-execute this handler with the remainder of the Rx bytes
594 	 * once we report actual number of bytes that we processed.
595 	 */
596 	deframer->state  = RAVE_SP_EXPECT_SOF;
597 	deframer->length = 0;
598 
599 	return src - buf;
600 }
601 
602 static int rave_sp_rdu1_cmd_translate(enum rave_sp_command command)
603 {
604 	if (command >= RAVE_SP_CMD_STATUS &&
605 	    command <= RAVE_SP_CMD_CONTROL_EVENTS)
606 		return command;
607 
608 	return -EINVAL;
609 }
610 
611 static int rave_sp_rdu2_cmd_translate(enum rave_sp_command command)
612 {
613 	if (command >= RAVE_SP_CMD_GET_FIRMWARE_VERSION &&
614 	    command <= RAVE_SP_CMD_GET_GPIO_STATE)
615 		return command;
616 
617 	if (command == RAVE_SP_CMD_REQ_COPPER_REV) {
618 		/*
619 		 * As per RDU2 ICD 3.4.47 CMD_GET_COPPER_REV code is
620 		 * different from that for RDU1 and it is set to 0x28.
621 		 */
622 		return 0x28;
623 	}
624 
625 	return rave_sp_rdu1_cmd_translate(command);
626 }
627 
628 static int rave_sp_default_cmd_translate(enum rave_sp_command command)
629 {
630 	/*
631 	 * All of the following command codes were taken from "Table :
632 	 * Communications Protocol Message Types" in section 3.3
633 	 * "MESSAGE TYPES" of Rave PIC24 ICD.
634 	 */
635 	switch (command) {
636 	case RAVE_SP_CMD_GET_FIRMWARE_VERSION:
637 		return 0x11;
638 	case RAVE_SP_CMD_GET_BOOTLOADER_VERSION:
639 		return 0x12;
640 	case RAVE_SP_CMD_BOOT_SOURCE:
641 		return 0x14;
642 	case RAVE_SP_CMD_SW_WDT:
643 		return 0x1C;
644 	case RAVE_SP_CMD_RESET:
645 		return 0x1E;
646 	case RAVE_SP_CMD_RESET_REASON:
647 		return 0x1F;
648 	default:
649 		return -EINVAL;
650 	}
651 }
652 
653 static const char *devm_rave_sp_version(struct device *dev,
654 					struct rave_sp_version *version)
655 {
656 	/*
657 	 * NOTE: The format string below uses %02d to display u16
658 	 * intentionally for the sake of backwards compatibility with
659 	 * legacy software.
660 	 */
661 	return devm_kasprintf(dev, GFP_KERNEL, "%02d%02d%02d.%c%c\n",
662 			      version->hardware,
663 			      le16_to_cpu(version->major),
664 			      version->minor,
665 			      version->letter[0],
666 			      version->letter[1]);
667 }
668 
669 static int rave_sp_get_status(struct rave_sp *sp)
670 {
671 	struct device *dev = &sp->serdev->dev;
672 	u8 cmd[] = {
673 		[0] = RAVE_SP_CMD_STATUS,
674 		[1] = 0
675 	};
676 	struct rave_sp_status status;
677 	const char *version;
678 	int ret;
679 
680 	ret = rave_sp_exec(sp, cmd, sizeof(cmd), &status, sizeof(status));
681 	if (ret)
682 		return ret;
683 
684 	version = devm_rave_sp_version(dev, &status.firmware_version);
685 	if (!version)
686 		return -ENOMEM;
687 
688 	sp->part_number_firmware = version;
689 
690 	version = devm_rave_sp_version(dev, &status.bootloader_version);
691 	if (!version)
692 		return -ENOMEM;
693 
694 	sp->part_number_bootloader = version;
695 
696 	return 0;
697 }
698 
699 static const struct rave_sp_checksum rave_sp_checksum_8b2c = {
700 	.length     = 1,
701 	.subroutine = csum_8b2c,
702 };
703 
704 static const struct rave_sp_checksum rave_sp_checksum_ccitt = {
705 	.length     = 2,
706 	.subroutine = csum_ccitt,
707 };
708 
709 static const struct rave_sp_variant rave_sp_legacy = {
710 	.checksum = &rave_sp_checksum_8b2c,
711 	.cmd = {
712 		.translate = rave_sp_default_cmd_translate,
713 	},
714 };
715 
716 static const struct rave_sp_variant rave_sp_rdu1 = {
717 	.checksum = &rave_sp_checksum_8b2c,
718 	.cmd = {
719 		.translate = rave_sp_rdu1_cmd_translate,
720 	},
721 };
722 
723 static const struct rave_sp_variant rave_sp_rdu2 = {
724 	.checksum = &rave_sp_checksum_ccitt,
725 	.cmd = {
726 		.translate = rave_sp_rdu2_cmd_translate,
727 	},
728 };
729 
730 static const struct of_device_id rave_sp_dt_ids[] = {
731 	{ .compatible = "zii,rave-sp-niu",  .data = &rave_sp_legacy },
732 	{ .compatible = "zii,rave-sp-mezz", .data = &rave_sp_legacy },
733 	{ .compatible = "zii,rave-sp-esb",  .data = &rave_sp_legacy },
734 	{ .compatible = "zii,rave-sp-rdu1", .data = &rave_sp_rdu1   },
735 	{ .compatible = "zii,rave-sp-rdu2", .data = &rave_sp_rdu2   },
736 	{ /* sentinel */ }
737 };
738 
739 static const struct serdev_device_ops rave_sp_serdev_device_ops = {
740 	.receive_buf  = rave_sp_receive_buf,
741 	.write_wakeup = serdev_device_write_wakeup,
742 };
743 
744 static int rave_sp_probe(struct serdev_device *serdev)
745 {
746 	struct device *dev = &serdev->dev;
747 	const char *unknown = "unknown\n";
748 	struct rave_sp *sp;
749 	u32 baud;
750 	int ret;
751 
752 	if (of_property_read_u32(dev->of_node, "current-speed", &baud)) {
753 		dev_err(dev,
754 			"'current-speed' is not specified in device node\n");
755 		return -EINVAL;
756 	}
757 
758 	sp = devm_kzalloc(dev, sizeof(*sp), GFP_KERNEL);
759 	if (!sp)
760 		return -ENOMEM;
761 
762 	sp->serdev = serdev;
763 	dev_set_drvdata(dev, sp);
764 
765 	sp->variant = of_device_get_match_data(dev);
766 	if (!sp->variant)
767 		return -ENODEV;
768 
769 	mutex_init(&sp->bus_lock);
770 	mutex_init(&sp->reply_lock);
771 	BLOCKING_INIT_NOTIFIER_HEAD(&sp->event_notifier_list);
772 
773 	serdev_device_set_client_ops(serdev, &rave_sp_serdev_device_ops);
774 	ret = devm_serdev_device_open(dev, serdev);
775 	if (ret)
776 		return ret;
777 
778 	serdev_device_set_baudrate(serdev, baud);
779 
780 	ret = rave_sp_get_status(sp);
781 	if (ret) {
782 		dev_warn(dev, "Failed to get firmware status: %d\n", ret);
783 		sp->part_number_firmware   = unknown;
784 		sp->part_number_bootloader = unknown;
785 	}
786 
787 	/*
788 	 * Those strings already have a \n embedded, so there's no
789 	 * need to have one in format string.
790 	 */
791 	dev_info(dev, "Firmware version: %s",   sp->part_number_firmware);
792 	dev_info(dev, "Bootloader version: %s", sp->part_number_bootloader);
793 
794 	return devm_of_platform_populate(dev);
795 }
796 
797 MODULE_DEVICE_TABLE(of, rave_sp_dt_ids);
798 
799 static struct serdev_device_driver rave_sp_drv = {
800 	.probe			= rave_sp_probe,
801 	.driver = {
802 		.name		= "rave-sp",
803 		.of_match_table	= rave_sp_dt_ids,
804 	},
805 };
806 module_serdev_device_driver(rave_sp_drv);
807 
808 MODULE_LICENSE("GPL");
809 MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
810 MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
811 MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
812 MODULE_DESCRIPTION("RAVE SP core driver");
813