xref: /openbmc/linux/drivers/mfd/rave-sp.c (revision 9470114d)
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_platform.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 /**
67  * enum rave_sp_deframer_state - Possible state for de-framer
68  *
69  * @RAVE_SP_EXPECT_SOF:		 Scanning input for start-of-frame marker
70  * @RAVE_SP_EXPECT_DATA:	 Got start of frame marker, collecting frame
71  * @RAVE_SP_EXPECT_ESCAPED_DATA: Got escape character, collecting escaped byte
72  */
73 enum rave_sp_deframer_state {
74 	RAVE_SP_EXPECT_SOF,
75 	RAVE_SP_EXPECT_DATA,
76 	RAVE_SP_EXPECT_ESCAPED_DATA,
77 };
78 
79 /**
80  * struct rave_sp_deframer - Device protocol deframer
81  *
82  * @state:  Current state of the deframer
83  * @data:   Buffer used to collect deframed data
84  * @length: Number of bytes de-framed so far
85  */
86 struct rave_sp_deframer {
87 	enum rave_sp_deframer_state state;
88 	unsigned char data[RAVE_SP_RX_BUFFER_SIZE];
89 	size_t length;
90 };
91 
92 /**
93  * struct rave_sp_reply - Reply as per RAVE device protocol
94  *
95  * @length:	Expected reply length
96  * @data:	Buffer to store reply payload in
97  * @code:	Expected reply code
98  * @ackid:	Expected reply ACK ID
99  * @received:   Successful reply reception completion
100  */
101 struct rave_sp_reply {
102 	size_t length;
103 	void  *data;
104 	u8     code;
105 	u8     ackid;
106 	struct completion received;
107 };
108 
109 /**
110  * struct rave_sp_checksum - Variant specific checksum implementation details
111  *
112  * @length:	Calculated checksum length
113  * @subroutine:	Utilized checksum algorithm implementation
114  */
115 struct rave_sp_checksum {
116 	size_t length;
117 	void (*subroutine)(const u8 *, size_t, u8 *);
118 };
119 
120 struct rave_sp_version {
121 	u8     hardware;
122 	__le16 major;
123 	u8     minor;
124 	u8     letter[2];
125 } __packed;
126 
127 struct rave_sp_status {
128 	struct rave_sp_version bootloader_version;
129 	struct rave_sp_version firmware_version;
130 	u16 rdu_eeprom_flag;
131 	u16 dds_eeprom_flag;
132 	u8  pic_flag;
133 	u8  orientation;
134 	u32 etc;
135 	s16 temp[2];
136 	u8  backlight_current[3];
137 	u8  dip_switch;
138 	u8  host_interrupt;
139 	u16 voltage_28;
140 	u8  i2c_device_status;
141 	u8  power_status;
142 	u8  general_status;
143 	u8  deprecated1;
144 	u8  power_led_status;
145 	u8  deprecated2;
146 	u8  periph_power_shutoff;
147 } __packed;
148 
149 /**
150  * struct rave_sp_variant_cmds - Variant specific command routines
151  *
152  * @translate:	Generic to variant specific command mapping routine
153  * @get_status: Variant specific implementation of CMD_GET_STATUS
154  */
155 struct rave_sp_variant_cmds {
156 	int (*translate)(enum rave_sp_command);
157 	int (*get_status)(struct rave_sp *sp, struct rave_sp_status *);
158 };
159 
160 /**
161  * struct rave_sp_variant - RAVE supervisory processor core variant
162  *
163  * @checksum:	Variant specific checksum implementation
164  * @cmd:	Variant specific command pointer table
165  *
166  */
167 struct rave_sp_variant {
168 	const struct rave_sp_checksum *checksum;
169 	struct rave_sp_variant_cmds cmd;
170 };
171 
172 /**
173  * struct rave_sp - RAVE supervisory processor core
174  *
175  * @serdev:			Pointer to underlying serdev
176  * @deframer:			Stored state of the protocol deframer
177  * @ackid:			ACK ID used in last reply sent to the device
178  * @bus_lock:			Lock to serialize access to the device
179  * @reply_lock:			Lock protecting @reply
180  * @reply:			Pointer to memory to store reply payload
181  *
182  * @variant:			Device variant specific information
183  * @event_notifier_list:	Input event notification chain
184  *
185  * @part_number_firmware:	Firmware version
186  * @part_number_bootloader:	Bootloader version
187  */
188 struct rave_sp {
189 	struct serdev_device *serdev;
190 	struct rave_sp_deframer deframer;
191 	atomic_t ackid;
192 	struct mutex bus_lock;
193 	struct mutex reply_lock;
194 	struct rave_sp_reply *reply;
195 
196 	const struct rave_sp_variant *variant;
197 	struct blocking_notifier_head event_notifier_list;
198 
199 	const char *part_number_firmware;
200 	const char *part_number_bootloader;
201 };
202 
203 static bool rave_sp_id_is_event(u8 code)
204 {
205 	return (code & 0xF0) == RAVE_SP_EVNT_BASE;
206 }
207 
208 static void rave_sp_unregister_event_notifier(struct device *dev, void *res)
209 {
210 	struct rave_sp *sp = dev_get_drvdata(dev->parent);
211 	struct notifier_block *nb = *(struct notifier_block **)res;
212 	struct blocking_notifier_head *bnh = &sp->event_notifier_list;
213 
214 	WARN_ON(blocking_notifier_chain_unregister(bnh, nb));
215 }
216 
217 int devm_rave_sp_register_event_notifier(struct device *dev,
218 					 struct notifier_block *nb)
219 {
220 	struct rave_sp *sp = dev_get_drvdata(dev->parent);
221 	struct notifier_block **rcnb;
222 	int ret;
223 
224 	rcnb = devres_alloc(rave_sp_unregister_event_notifier,
225 			    sizeof(*rcnb), GFP_KERNEL);
226 	if (!rcnb)
227 		return -ENOMEM;
228 
229 	ret = blocking_notifier_chain_register(&sp->event_notifier_list, nb);
230 	if (!ret) {
231 		*rcnb = nb;
232 		devres_add(dev, rcnb);
233 	} else {
234 		devres_free(rcnb);
235 	}
236 
237 	return ret;
238 }
239 EXPORT_SYMBOL_GPL(devm_rave_sp_register_event_notifier);
240 
241 static void csum_8b2c(const u8 *buf, size_t size, u8 *crc)
242 {
243 	*crc = *buf++;
244 	size--;
245 
246 	while (size--)
247 		*crc += *buf++;
248 
249 	*crc = 1 + ~(*crc);
250 }
251 
252 static void csum_ccitt(const u8 *buf, size_t size, u8 *crc)
253 {
254 	const u16 calculated = crc_ccitt_false(0xffff, buf, size);
255 
256 	/*
257 	 * While the rest of the wire protocol is little-endian,
258 	 * CCITT-16 CRC in RDU2 device is sent out in big-endian order.
259 	 */
260 	put_unaligned_be16(calculated, crc);
261 }
262 
263 static void *stuff(unsigned char *dest, const unsigned char *src, size_t n)
264 {
265 	while (n--) {
266 		const unsigned char byte = *src++;
267 
268 		switch (byte) {
269 		case RAVE_SP_STX:
270 		case RAVE_SP_ETX:
271 		case RAVE_SP_DLE:
272 			*dest++ = RAVE_SP_DLE;
273 			fallthrough;
274 		default:
275 			*dest++ = byte;
276 		}
277 	}
278 
279 	return dest;
280 }
281 
282 static int rave_sp_write(struct rave_sp *sp, const u8 *data, u8 data_size)
283 {
284 	const size_t checksum_length = sp->variant->checksum->length;
285 	unsigned char frame[RAVE_SP_TX_BUFFER_SIZE];
286 	unsigned char crc[RAVE_SP_CHECKSUM_SIZE];
287 	unsigned char *dest = frame;
288 	size_t length;
289 
290 	if (WARN_ON(checksum_length > sizeof(crc)))
291 		return -ENOMEM;
292 
293 	if (WARN_ON(data_size > sizeof(frame)))
294 		return -ENOMEM;
295 
296 	sp->variant->checksum->subroutine(data, data_size, crc);
297 
298 	*dest++ = RAVE_SP_STX;
299 	dest = stuff(dest, data, data_size);
300 	dest = stuff(dest, crc, checksum_length);
301 	*dest++ = RAVE_SP_ETX;
302 
303 	length = dest - frame;
304 
305 	print_hex_dump_debug("rave-sp tx: ", DUMP_PREFIX_NONE,
306 			     16, 1, frame, length, false);
307 
308 	return serdev_device_write(sp->serdev, frame, length, HZ);
309 }
310 
311 static u8 rave_sp_reply_code(u8 command)
312 {
313 	/*
314 	 * There isn't a single rule that describes command code ->
315 	 * ACK code transformation, but, going through various
316 	 * versions of ICDs, there appear to be three distinct groups
317 	 * that can be described by simple transformation.
318 	 */
319 	switch (command) {
320 	case 0xA0 ... 0xBE:
321 		/*
322 		 * Commands implemented by firmware found in RDU1 and
323 		 * older devices all seem to obey the following rule
324 		 */
325 		return command + 0x20;
326 	case 0xE0 ... 0xEF:
327 		/*
328 		 * Events emitted by all versions of the firmare use
329 		 * least significant bit to get an ACK code
330 		 */
331 		return command | 0x01;
332 	default:
333 		/*
334 		 * Commands implemented by firmware found in RDU2 are
335 		 * similar to "old" commands, but they use slightly
336 		 * different offset
337 		 */
338 		return command + 0x40;
339 	}
340 }
341 
342 int rave_sp_exec(struct rave_sp *sp,
343 		 void *__data,  size_t data_size,
344 		 void *reply_data, size_t reply_data_size)
345 {
346 	struct rave_sp_reply reply = {
347 		.data     = reply_data,
348 		.length   = reply_data_size,
349 		.received = COMPLETION_INITIALIZER_ONSTACK(reply.received),
350 	};
351 	unsigned char *data = __data;
352 	int command, ret = 0;
353 	u8 ackid;
354 
355 	command = sp->variant->cmd.translate(data[0]);
356 	if (command < 0)
357 		return command;
358 
359 	ackid       = atomic_inc_return(&sp->ackid);
360 	reply.ackid = ackid;
361 	reply.code  = rave_sp_reply_code((u8)command),
362 
363 	mutex_lock(&sp->bus_lock);
364 
365 	mutex_lock(&sp->reply_lock);
366 	sp->reply = &reply;
367 	mutex_unlock(&sp->reply_lock);
368 
369 	data[0] = command;
370 	data[1] = ackid;
371 
372 	rave_sp_write(sp, data, data_size);
373 
374 	if (!wait_for_completion_timeout(&reply.received, HZ)) {
375 		dev_err(&sp->serdev->dev, "Command timeout\n");
376 		ret = -ETIMEDOUT;
377 
378 		mutex_lock(&sp->reply_lock);
379 		sp->reply = NULL;
380 		mutex_unlock(&sp->reply_lock);
381 	}
382 
383 	mutex_unlock(&sp->bus_lock);
384 	return ret;
385 }
386 EXPORT_SYMBOL_GPL(rave_sp_exec);
387 
388 static void rave_sp_receive_event(struct rave_sp *sp,
389 				  const unsigned char *data, size_t length)
390 {
391 	u8 cmd[] = {
392 		[0] = rave_sp_reply_code(data[0]),
393 		[1] = data[1],
394 	};
395 
396 	rave_sp_write(sp, cmd, sizeof(cmd));
397 
398 	blocking_notifier_call_chain(&sp->event_notifier_list,
399 				     rave_sp_action_pack(data[0], data[2]),
400 				     NULL);
401 }
402 
403 static void rave_sp_receive_reply(struct rave_sp *sp,
404 				  const unsigned char *data, size_t length)
405 {
406 	struct device *dev = &sp->serdev->dev;
407 	struct rave_sp_reply *reply;
408 	const  size_t payload_length = length - 2;
409 
410 	mutex_lock(&sp->reply_lock);
411 	reply = sp->reply;
412 
413 	if (reply) {
414 		if (reply->code == data[0] && reply->ackid == data[1] &&
415 		    payload_length >= reply->length) {
416 			/*
417 			 * We are relying on memcpy(dst, src, 0) to be a no-op
418 			 * when handling commands that have a no-payload reply
419 			 */
420 			memcpy(reply->data, &data[2], reply->length);
421 			complete(&reply->received);
422 			sp->reply = NULL;
423 		} else {
424 			dev_err(dev, "Ignoring incorrect reply\n");
425 			dev_dbg(dev, "Code:   expected = 0x%08x received = 0x%08x\n",
426 				reply->code, data[0]);
427 			dev_dbg(dev, "ACK ID: expected = 0x%08x received = 0x%08x\n",
428 				reply->ackid, data[1]);
429 			dev_dbg(dev, "Length: expected = %zu received = %zu\n",
430 				reply->length, payload_length);
431 		}
432 	}
433 
434 	mutex_unlock(&sp->reply_lock);
435 }
436 
437 static void rave_sp_receive_frame(struct rave_sp *sp,
438 				  const unsigned char *data,
439 				  size_t length)
440 {
441 	const size_t checksum_length = sp->variant->checksum->length;
442 	const size_t payload_length  = length - checksum_length;
443 	const u8 *crc_reported       = &data[payload_length];
444 	struct device *dev           = &sp->serdev->dev;
445 	u8 crc_calculated[RAVE_SP_CHECKSUM_SIZE];
446 
447 	if (unlikely(checksum_length > sizeof(crc_calculated))) {
448 		dev_warn(dev, "Checksum too long, dropping\n");
449 		return;
450 	}
451 
452 	print_hex_dump_debug("rave-sp rx: ", DUMP_PREFIX_NONE,
453 			     16, 1, data, length, false);
454 
455 	if (unlikely(length <= checksum_length)) {
456 		dev_warn(dev, "Dropping short frame\n");
457 		return;
458 	}
459 
460 	sp->variant->checksum->subroutine(data, payload_length,
461 					  crc_calculated);
462 
463 	if (memcmp(crc_calculated, crc_reported, checksum_length)) {
464 		dev_warn(dev, "Dropping bad frame\n");
465 		return;
466 	}
467 
468 	if (rave_sp_id_is_event(data[0]))
469 		rave_sp_receive_event(sp, data, length);
470 	else
471 		rave_sp_receive_reply(sp, data, length);
472 }
473 
474 static int rave_sp_receive_buf(struct serdev_device *serdev,
475 			       const unsigned char *buf, size_t size)
476 {
477 	struct device *dev = &serdev->dev;
478 	struct rave_sp *sp = dev_get_drvdata(dev);
479 	struct rave_sp_deframer *deframer = &sp->deframer;
480 	const unsigned char *src = buf;
481 	const unsigned char *end = buf + size;
482 
483 	while (src < end) {
484 		const unsigned char byte = *src++;
485 
486 		switch (deframer->state) {
487 		case RAVE_SP_EXPECT_SOF:
488 			if (byte == RAVE_SP_STX)
489 				deframer->state = RAVE_SP_EXPECT_DATA;
490 			break;
491 
492 		case RAVE_SP_EXPECT_DATA:
493 			/*
494 			 * Treat special byte values first
495 			 */
496 			switch (byte) {
497 			case RAVE_SP_ETX:
498 				rave_sp_receive_frame(sp,
499 						      deframer->data,
500 						      deframer->length);
501 				/*
502 				 * Once we extracted a complete frame
503 				 * out of a stream, we call it done
504 				 * and proceed to bailing out while
505 				 * resetting the framer to initial
506 				 * state, regardless if we've consumed
507 				 * all of the stream or not.
508 				 */
509 				goto reset_framer;
510 			case RAVE_SP_STX:
511 				dev_warn(dev, "Bad frame: STX before ETX\n");
512 				/*
513 				 * If we encounter second "start of
514 				 * the frame" marker before seeing
515 				 * corresponding "end of frame", we
516 				 * reset the framer and ignore both:
517 				 * frame started by first SOF and
518 				 * frame started by current SOF.
519 				 *
520 				 * NOTE: The above means that only the
521 				 * frame started by third SOF, sent
522 				 * after this one will have a chance
523 				 * to get throught.
524 				 */
525 				goto reset_framer;
526 			case RAVE_SP_DLE:
527 				deframer->state = RAVE_SP_EXPECT_ESCAPED_DATA;
528 				/*
529 				 * If we encounter escape sequence we
530 				 * need to skip it and collect the
531 				 * byte that follows. We do it by
532 				 * forcing the next iteration of the
533 				 * encompassing while loop.
534 				 */
535 				continue;
536 			}
537 			/*
538 			 * For the rest of the bytes, that are not
539 			 * speical snoflakes, we do the same thing
540 			 * that we do to escaped data - collect it in
541 			 * deframer buffer
542 			 */
543 
544 			fallthrough;
545 
546 		case RAVE_SP_EXPECT_ESCAPED_DATA:
547 			if (deframer->length == sizeof(deframer->data)) {
548 				dev_warn(dev, "Bad frame: Too long\n");
549 				/*
550 				 * If the amount of data we've
551 				 * accumulated for current frame so
552 				 * far starts to exceed the capacity
553 				 * of deframer's buffer, there's
554 				 * nothing else we can do but to
555 				 * discard that data and start
556 				 * assemblying a new frame again
557 				 */
558 				goto reset_framer;
559 			}
560 
561 			deframer->data[deframer->length++] = byte;
562 
563 			/*
564 			 * We've extracted out special byte, now we
565 			 * can go back to regular data collecting
566 			 */
567 			deframer->state = RAVE_SP_EXPECT_DATA;
568 			break;
569 		}
570 	}
571 
572 	/*
573 	 * The only way to get out of the above loop and end up here
574 	 * is throught consuming all of the supplied data, so here we
575 	 * report that we processed it all.
576 	 */
577 	return size;
578 
579 reset_framer:
580 	/*
581 	 * NOTE: A number of codepaths that will drop us here will do
582 	 * so before consuming all 'size' bytes of the data passed by
583 	 * serdev layer. We rely on the fact that serdev layer will
584 	 * re-execute this handler with the remainder of the Rx bytes
585 	 * once we report actual number of bytes that we processed.
586 	 */
587 	deframer->state  = RAVE_SP_EXPECT_SOF;
588 	deframer->length = 0;
589 
590 	return src - buf;
591 }
592 
593 static int rave_sp_rdu1_cmd_translate(enum rave_sp_command command)
594 {
595 	if (command >= RAVE_SP_CMD_STATUS &&
596 	    command <= RAVE_SP_CMD_CONTROL_EVENTS)
597 		return command;
598 
599 	return -EINVAL;
600 }
601 
602 static int rave_sp_rdu2_cmd_translate(enum rave_sp_command command)
603 {
604 	if (command >= RAVE_SP_CMD_GET_FIRMWARE_VERSION &&
605 	    command <= RAVE_SP_CMD_GET_GPIO_STATE)
606 		return command;
607 
608 	if (command == RAVE_SP_CMD_REQ_COPPER_REV) {
609 		/*
610 		 * As per RDU2 ICD 3.4.47 CMD_GET_COPPER_REV code is
611 		 * different from that for RDU1 and it is set to 0x28.
612 		 */
613 		return 0x28;
614 	}
615 
616 	return rave_sp_rdu1_cmd_translate(command);
617 }
618 
619 static int rave_sp_default_cmd_translate(enum rave_sp_command command)
620 {
621 	/*
622 	 * All of the following command codes were taken from "Table :
623 	 * Communications Protocol Message Types" in section 3.3
624 	 * "MESSAGE TYPES" of Rave PIC24 ICD.
625 	 */
626 	switch (command) {
627 	case RAVE_SP_CMD_GET_FIRMWARE_VERSION:
628 		return 0x11;
629 	case RAVE_SP_CMD_GET_BOOTLOADER_VERSION:
630 		return 0x12;
631 	case RAVE_SP_CMD_BOOT_SOURCE:
632 		return 0x14;
633 	case RAVE_SP_CMD_SW_WDT:
634 		return 0x1C;
635 	case RAVE_SP_CMD_PET_WDT:
636 		return 0x1D;
637 	case RAVE_SP_CMD_RESET:
638 		return 0x1E;
639 	case RAVE_SP_CMD_RESET_REASON:
640 		return 0x1F;
641 	case RAVE_SP_CMD_RMB_EEPROM:
642 		return 0x20;
643 	default:
644 		return -EINVAL;
645 	}
646 }
647 
648 static const char *devm_rave_sp_version(struct device *dev,
649 					struct rave_sp_version *version)
650 {
651 	/*
652 	 * NOTE: The format string below uses %02d to display u16
653 	 * intentionally for the sake of backwards compatibility with
654 	 * legacy software.
655 	 */
656 	return devm_kasprintf(dev, GFP_KERNEL, "%02d%02d%02d.%c%c\n",
657 			      version->hardware,
658 			      le16_to_cpu(version->major),
659 			      version->minor,
660 			      version->letter[0],
661 			      version->letter[1]);
662 }
663 
664 static int rave_sp_rdu1_get_status(struct rave_sp *sp,
665 				   struct rave_sp_status *status)
666 {
667 	u8 cmd[] = {
668 		[0] = RAVE_SP_CMD_STATUS,
669 		[1] = 0
670 	};
671 
672 	return rave_sp_exec(sp, cmd, sizeof(cmd), status, sizeof(*status));
673 }
674 
675 static int rave_sp_emulated_get_status(struct rave_sp *sp,
676 				       struct rave_sp_status *status)
677 {
678 	u8 cmd[] = {
679 		[0] = RAVE_SP_CMD_GET_FIRMWARE_VERSION,
680 		[1] = 0,
681 	};
682 	int ret;
683 
684 	ret = rave_sp_exec(sp, cmd, sizeof(cmd), &status->firmware_version,
685 			   sizeof(status->firmware_version));
686 	if (ret)
687 		return ret;
688 
689 	cmd[0] = RAVE_SP_CMD_GET_BOOTLOADER_VERSION;
690 	return rave_sp_exec(sp, cmd, sizeof(cmd), &status->bootloader_version,
691 			    sizeof(status->bootloader_version));
692 }
693 
694 static int rave_sp_get_status(struct rave_sp *sp)
695 {
696 	struct device *dev = &sp->serdev->dev;
697 	struct rave_sp_status status;
698 	const char *version;
699 	int ret;
700 
701 	ret = sp->variant->cmd.get_status(sp, &status);
702 	if (ret)
703 		return ret;
704 
705 	version = devm_rave_sp_version(dev, &status.firmware_version);
706 	if (!version)
707 		return -ENOMEM;
708 
709 	sp->part_number_firmware = version;
710 
711 	version = devm_rave_sp_version(dev, &status.bootloader_version);
712 	if (!version)
713 		return -ENOMEM;
714 
715 	sp->part_number_bootloader = version;
716 
717 	return 0;
718 }
719 
720 static const struct rave_sp_checksum rave_sp_checksum_8b2c = {
721 	.length     = 1,
722 	.subroutine = csum_8b2c,
723 };
724 
725 static const struct rave_sp_checksum rave_sp_checksum_ccitt = {
726 	.length     = 2,
727 	.subroutine = csum_ccitt,
728 };
729 
730 static const struct rave_sp_variant rave_sp_legacy = {
731 	.checksum = &rave_sp_checksum_ccitt,
732 	.cmd = {
733 		.translate = rave_sp_default_cmd_translate,
734 		.get_status = rave_sp_emulated_get_status,
735 	},
736 };
737 
738 static const struct rave_sp_variant rave_sp_rdu1 = {
739 	.checksum = &rave_sp_checksum_8b2c,
740 	.cmd = {
741 		.translate = rave_sp_rdu1_cmd_translate,
742 		.get_status = rave_sp_rdu1_get_status,
743 	},
744 };
745 
746 static const struct rave_sp_variant rave_sp_rdu2 = {
747 	.checksum = &rave_sp_checksum_ccitt,
748 	.cmd = {
749 		.translate = rave_sp_rdu2_cmd_translate,
750 		.get_status = rave_sp_emulated_get_status,
751 	},
752 };
753 
754 static const struct of_device_id rave_sp_dt_ids[] = {
755 	{ .compatible = "zii,rave-sp-niu",  .data = &rave_sp_legacy },
756 	{ .compatible = "zii,rave-sp-mezz", .data = &rave_sp_legacy },
757 	{ .compatible = "zii,rave-sp-esb",  .data = &rave_sp_legacy },
758 	{ .compatible = "zii,rave-sp-rdu1", .data = &rave_sp_rdu1   },
759 	{ .compatible = "zii,rave-sp-rdu2", .data = &rave_sp_rdu2   },
760 	{ /* sentinel */ }
761 };
762 
763 static const struct serdev_device_ops rave_sp_serdev_device_ops = {
764 	.receive_buf  = rave_sp_receive_buf,
765 	.write_wakeup = serdev_device_write_wakeup,
766 };
767 
768 static int rave_sp_probe(struct serdev_device *serdev)
769 {
770 	struct device *dev = &serdev->dev;
771 	const char *unknown = "unknown\n";
772 	struct rave_sp *sp;
773 	u32 baud;
774 	int ret;
775 
776 	if (of_property_read_u32(dev->of_node, "current-speed", &baud)) {
777 		dev_err(dev,
778 			"'current-speed' is not specified in device node\n");
779 		return -EINVAL;
780 	}
781 
782 	sp = devm_kzalloc(dev, sizeof(*sp), GFP_KERNEL);
783 	if (!sp)
784 		return -ENOMEM;
785 
786 	sp->serdev = serdev;
787 	dev_set_drvdata(dev, sp);
788 
789 	sp->variant = of_device_get_match_data(dev);
790 	if (!sp->variant)
791 		return -ENODEV;
792 
793 	mutex_init(&sp->bus_lock);
794 	mutex_init(&sp->reply_lock);
795 	BLOCKING_INIT_NOTIFIER_HEAD(&sp->event_notifier_list);
796 
797 	serdev_device_set_client_ops(serdev, &rave_sp_serdev_device_ops);
798 	ret = devm_serdev_device_open(dev, serdev);
799 	if (ret)
800 		return ret;
801 
802 	serdev_device_set_baudrate(serdev, baud);
803 	serdev_device_set_flow_control(serdev, false);
804 
805 	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
806 	if (ret) {
807 		dev_err(dev, "Failed to set parity\n");
808 		return ret;
809 	}
810 
811 	ret = rave_sp_get_status(sp);
812 	if (ret) {
813 		dev_warn(dev, "Failed to get firmware status: %d\n", ret);
814 		sp->part_number_firmware   = unknown;
815 		sp->part_number_bootloader = unknown;
816 	}
817 
818 	/*
819 	 * Those strings already have a \n embedded, so there's no
820 	 * need to have one in format string.
821 	 */
822 	dev_info(dev, "Firmware version: %s",   sp->part_number_firmware);
823 	dev_info(dev, "Bootloader version: %s", sp->part_number_bootloader);
824 
825 	return devm_of_platform_populate(dev);
826 }
827 
828 MODULE_DEVICE_TABLE(of, rave_sp_dt_ids);
829 
830 static struct serdev_device_driver rave_sp_drv = {
831 	.probe			= rave_sp_probe,
832 	.driver = {
833 		.name		= "rave-sp",
834 		.of_match_table	= rave_sp_dt_ids,
835 	},
836 };
837 module_serdev_device_driver(rave_sp_drv);
838 
839 MODULE_LICENSE("GPL");
840 MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
841 MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
842 MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
843 MODULE_DESCRIPTION("RAVE SP core driver");
844