xref: /linux/drivers/w1/masters/ds2490.c (revision 8e07e0e3964ca4e23ce7b68e2096fe660a888942)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	ds2490.c  USB to one wire bridge
4  *
5  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
6  */
7 
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/mod_devicetable.h>
11 #include <linux/usb.h>
12 #include <linux/slab.h>
13 
14 #include <linux/w1.h>
15 
16 /* USB Standard */
17 /* USB Control request vendor type */
18 #define VENDOR				0x40
19 
20 /* COMMAND TYPE CODES */
21 #define CONTROL_CMD			0x00
22 #define COMM_CMD			0x01
23 #define MODE_CMD			0x02
24 
25 /* CONTROL COMMAND CODES */
26 #define CTL_RESET_DEVICE		0x0000
27 #define CTL_START_EXE			0x0001
28 #define CTL_RESUME_EXE			0x0002
29 #define CTL_HALT_EXE_IDLE		0x0003
30 #define CTL_HALT_EXE_DONE		0x0004
31 #define CTL_FLUSH_COMM_CMDS		0x0007
32 #define CTL_FLUSH_RCV_BUFFER		0x0008
33 #define CTL_FLUSH_XMT_BUFFER		0x0009
34 #define CTL_GET_COMM_CMDS		0x000A
35 
36 /* MODE COMMAND CODES */
37 #define MOD_PULSE_EN			0x0000
38 #define MOD_SPEED_CHANGE_EN		0x0001
39 #define MOD_1WIRE_SPEED			0x0002
40 #define MOD_STRONG_PU_DURATION		0x0003
41 #define MOD_PULLDOWN_SLEWRATE		0x0004
42 #define MOD_PROG_PULSE_DURATION		0x0005
43 #define MOD_WRITE1_LOWTIME		0x0006
44 #define MOD_DSOW0_TREC			0x0007
45 
46 /* COMMUNICATION COMMAND CODES */
47 #define COMM_ERROR_ESCAPE		0x0601
48 #define COMM_SET_DURATION		0x0012
49 #define COMM_BIT_IO			0x0020
50 #define COMM_PULSE			0x0030
51 #define COMM_1_WIRE_RESET		0x0042
52 #define COMM_BYTE_IO			0x0052
53 #define COMM_MATCH_ACCESS		0x0064
54 #define COMM_BLOCK_IO			0x0074
55 #define COMM_READ_STRAIGHT		0x0080
56 #define COMM_DO_RELEASE			0x6092
57 #define COMM_SET_PATH			0x00A2
58 #define COMM_WRITE_SRAM_PAGE		0x00B2
59 #define COMM_WRITE_EPROM		0x00C4
60 #define COMM_READ_CRC_PROT_PAGE		0x00D4
61 #define COMM_READ_REDIRECT_PAGE_CRC	0x21E4
62 #define COMM_SEARCH_ACCESS		0x00F4
63 
64 /* Communication command bits */
65 #define COMM_TYPE			0x0008
66 #define COMM_SE				0x0008
67 #define COMM_D				0x0008
68 #define COMM_Z				0x0008
69 #define COMM_CH				0x0008
70 #define COMM_SM				0x0008
71 #define COMM_R				0x0008
72 #define COMM_IM				0x0001
73 
74 #define COMM_PS				0x4000
75 #define COMM_PST			0x4000
76 #define COMM_CIB			0x4000
77 #define COMM_RTS			0x4000
78 #define COMM_DT				0x2000
79 #define COMM_SPU			0x1000
80 #define COMM_F				0x0800
81 #define COMM_NTF			0x0400
82 #define COMM_ICP			0x0200
83 #define COMM_RST			0x0100
84 
85 #define PULSE_PROG			0x01
86 #define PULSE_SPUE			0x02
87 
88 #define BRANCH_MAIN			0xCC
89 #define BRANCH_AUX			0x33
90 
91 /* Status flags */
92 #define ST_SPUA				0x01  /* Strong Pull-up is active */
93 #define ST_PRGA				0x02  /* 12V programming pulse is being generated */
94 #define ST_12VP				0x04  /* external 12V programming voltage is present */
95 #define ST_PMOD				0x08  /* DS2490 powered from USB and external sources */
96 #define ST_HALT				0x10  /* DS2490 is currently halted */
97 #define ST_IDLE				0x20  /* DS2490 is currently idle */
98 #define ST_EPOF				0x80
99 /* Status transfer size, 16 bytes status, 16 byte result flags */
100 #define ST_SIZE				0x20
101 
102 /* Result Register flags */
103 #define RR_DETECT			0xA5 /* New device detected */
104 #define RR_NRS				0x01 /* Reset no presence or ... */
105 #define RR_SH				0x02 /* short on reset or set path */
106 #define RR_APP				0x04 /* alarming presence on reset */
107 #define RR_VPP				0x08 /* 12V expected not seen */
108 #define RR_CMP				0x10 /* compare error */
109 #define RR_CRC				0x20 /* CRC error detected */
110 #define RR_RDP				0x40 /* redirected page */
111 #define RR_EOS				0x80 /* end of search error */
112 
113 #define SPEED_NORMAL			0x00
114 #define SPEED_FLEXIBLE			0x01
115 #define SPEED_OVERDRIVE			0x02
116 
117 #define NUM_EP				4
118 #define EP_CONTROL			0
119 #define EP_STATUS			1
120 #define EP_DATA_OUT			2
121 #define EP_DATA_IN			3
122 
123 struct ds_device {
124 	struct list_head	ds_entry;
125 
126 	struct usb_device	*udev;
127 	struct usb_interface	*intf;
128 
129 	int			ep[NUM_EP];
130 
131 	/* Strong PullUp
132 	 * 0: pullup not active, else duration in milliseconds
133 	 */
134 	int			spu_sleep;
135 	/* spu_bit contains COMM_SPU or 0 depending on if the strong pullup
136 	 * should be active or not for writes.
137 	 */
138 	u16			spu_bit;
139 
140 	u8			st_buf[ST_SIZE];
141 	u8			byte_buf;
142 
143 	struct w1_bus_master	master;
144 };
145 
146 struct ds_status {
147 	u8			enable;
148 	u8			speed;
149 	u8			pullup_dur;
150 	u8			ppuls_dur;
151 	u8			pulldown_slew;
152 	u8			write1_time;
153 	u8			write0_time;
154 	u8			reserved0;
155 	u8			status;
156 	u8			command0;
157 	u8			command1;
158 	u8			command_buffer_status;
159 	u8			data_out_buffer_status;
160 	u8			data_in_buffer_status;
161 	u8			reserved1;
162 	u8			reserved2;
163 };
164 
165 static LIST_HEAD(ds_devices);
166 static DEFINE_MUTEX(ds_mutex);
167 
168 static int ds_send_control_cmd(struct ds_device *dev, u16 value, u16 index)
169 {
170 	int err;
171 
172 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
173 			CONTROL_CMD, VENDOR, value, index, NULL, 0, 1000);
174 	if (err < 0) {
175 		dev_err(&dev->udev->dev,
176 			"Failed to send command control message %x.%x: err=%d.\n",
177 			value, index, err);
178 		return err;
179 	}
180 
181 	return err;
182 }
183 
184 static int ds_send_control_mode(struct ds_device *dev, u16 value, u16 index)
185 {
186 	int err;
187 
188 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
189 			MODE_CMD, VENDOR, value, index, NULL, 0, 1000);
190 	if (err < 0) {
191 		dev_err(&dev->udev->dev,
192 			"Failed to send mode control message %x.%x: err=%d.\n",
193 			value, index, err);
194 		return err;
195 	}
196 
197 	return err;
198 }
199 
200 static int ds_send_control(struct ds_device *dev, u16 value, u16 index)
201 {
202 	int err;
203 
204 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
205 			COMM_CMD, VENDOR, value, index, NULL, 0, 1000);
206 	if (err < 0) {
207 		dev_err(&dev->udev->dev,
208 			"Failed to send control message %x.%x: err=%d.\n",
209 			value, index, err);
210 		return err;
211 	}
212 
213 	return err;
214 }
215 
216 static void ds_dump_status(struct ds_device *ds_dev, unsigned char *buf, int count)
217 {
218 	struct device *dev = &ds_dev->udev->dev;
219 	int i;
220 
221 	dev_info(dev, "ep_status=0x%x, count=%d, status=%*phC",
222 		ds_dev->ep[EP_STATUS], count, count, buf);
223 
224 	if (count >= 16) {
225 		dev_dbg(dev, "enable flag: 0x%02x", buf[0]);
226 		dev_dbg(dev, "1-wire speed: 0x%02x", buf[1]);
227 		dev_dbg(dev, "strong pullup duration: 0x%02x", buf[2]);
228 		dev_dbg(dev, "programming pulse duration: 0x%02x", buf[3]);
229 		dev_dbg(dev, "pulldown slew rate control: 0x%02x", buf[4]);
230 		dev_dbg(dev, "write-1 low time: 0x%02x", buf[5]);
231 		dev_dbg(dev, "data sample offset/write-0 recovery time: 0x%02x", buf[6]);
232 		dev_dbg(dev, "reserved (test register): 0x%02x", buf[7]);
233 		dev_dbg(dev, "device status flags: 0x%02x", buf[8]);
234 		dev_dbg(dev, "communication command byte 1: 0x%02x", buf[9]);
235 		dev_dbg(dev, "communication command byte 2: 0x%02x", buf[10]);
236 		dev_dbg(dev, "communication command buffer status: 0x%02x", buf[11]);
237 		dev_dbg(dev, "1-wire data output buffer status: 0x%02x", buf[12]);
238 		dev_dbg(dev, "1-wire data input buffer status: 0x%02x", buf[13]);
239 		dev_dbg(dev, "reserved: 0x%02x", buf[14]);
240 		dev_dbg(dev, "reserved: 0x%02x", buf[15]);
241 	}
242 
243 	for (i = 16; i < count; ++i) {
244 		if (buf[i] == RR_DETECT) {
245 			dev_dbg(dev, "New device detect.\n");
246 			continue;
247 		}
248 		dev_dbg(dev, "Result Register Value: 0x%02x", buf[i]);
249 		if (buf[i] & RR_NRS)
250 			dev_dbg(dev, "NRS: Reset no presence or ...\n");
251 		if (buf[i] & RR_SH)
252 			dev_dbg(dev, "SH: short on reset or set path\n");
253 		if (buf[i] & RR_APP)
254 			dev_dbg(dev, "APP: alarming presence on reset\n");
255 		if (buf[i] & RR_VPP)
256 			dev_dbg(dev, "VPP: 12V expected not seen\n");
257 		if (buf[i] & RR_CMP)
258 			dev_dbg(dev, "CMP: compare error\n");
259 		if (buf[i] & RR_CRC)
260 			dev_dbg(dev, "CRC: CRC error detected\n");
261 		if (buf[i] & RR_RDP)
262 			dev_dbg(dev, "RDP: redirected page\n");
263 		if (buf[i] & RR_EOS)
264 			dev_dbg(dev, "EOS: end of search error\n");
265 	}
266 }
267 
268 static int ds_recv_status(struct ds_device *dev, struct ds_status *st)
269 {
270 	int count, err;
271 
272 	if (st)
273 		memset(st, 0, sizeof(*st));
274 
275 	count = 0;
276 	err = usb_interrupt_msg(dev->udev,
277 				usb_rcvintpipe(dev->udev,
278 					       dev->ep[EP_STATUS]),
279 				dev->st_buf, sizeof(dev->st_buf),
280 				&count, 1000);
281 	if (err < 0) {
282 		dev_err(&dev->udev->dev,
283 			"Failed to read 1-wire data from 0x%x: err=%d.\n",
284 			dev->ep[EP_STATUS], err);
285 		return err;
286 	}
287 
288 	if (st && count >= sizeof(*st))
289 		memcpy(st, dev->st_buf, sizeof(*st));
290 
291 	return count;
292 }
293 
294 static void ds_reset_device(struct ds_device *dev)
295 {
296 	ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
297 	/* Always allow strong pullup which allow individual writes to use
298 	 * the strong pullup.
299 	 */
300 	if (ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_SPUE))
301 		dev_err(&dev->udev->dev,
302 			"%s: Error allowing strong pullup\n", __func__);
303 	/* Chip strong pullup time was cleared. */
304 	if (dev->spu_sleep) {
305 		/* lower 4 bits are 0, see ds_set_pullup */
306 		u8 del = dev->spu_sleep>>4;
307 
308 		if (ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del))
309 			dev_err(&dev->udev->dev,
310 				"%s: Error setting duration\n", __func__);
311 	}
312 }
313 
314 static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
315 {
316 	int count, err;
317 
318 	/* Careful on size.  If size is less than what is available in
319 	 * the input buffer, the device fails the bulk transfer and
320 	 * clears the input buffer.  It could read the maximum size of
321 	 * the data buffer, but then do you return the first, last, or
322 	 * some set of the middle size bytes?  As long as the rest of
323 	 * the code is correct there will be size bytes waiting.  A
324 	 * call to ds_wait_status will wait until the device is idle
325 	 * and any data to be received would have been available.
326 	 */
327 	count = 0;
328 	err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]),
329 				buf, size, &count, 1000);
330 	if (err < 0) {
331 		int recv_len;
332 
333 		dev_info(&dev->udev->dev, "Clearing ep0x%x.\n", dev->ep[EP_DATA_IN]);
334 		usb_clear_halt(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]));
335 
336 		/* status might tell us why endpoint is stuck? */
337 		recv_len = ds_recv_status(dev, NULL);
338 		if (recv_len >= 0)
339 			ds_dump_status(dev, dev->st_buf, recv_len);
340 
341 		return err;
342 	}
343 
344 #if 0
345 	{
346 		int i;
347 
348 		printk("%s: count=%d: ", __func__, count);
349 		for (i = 0; i < count; ++i)
350 			printk("%02x ", buf[i]);
351 		printk("\n");
352 	}
353 #endif
354 	return count;
355 }
356 
357 static int ds_send_data(struct ds_device *dev, unsigned char *buf, int len)
358 {
359 	int count, err;
360 
361 	count = 0;
362 	err = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, dev->ep[EP_DATA_OUT]), buf, len, &count, 1000);
363 	if (err < 0) {
364 		dev_err(&dev->udev->dev, "Failed to write 1-wire data to ep0x%x: "
365 			"err=%d.\n", dev->ep[EP_DATA_OUT], err);
366 		return err;
367 	}
368 
369 	return err;
370 }
371 
372 #if 0
373 
374 int ds_stop_pulse(struct ds_device *dev, int limit)
375 {
376 	struct ds_status st;
377 	int count = 0, err = 0;
378 
379 	do {
380 		err = ds_send_control(dev, CTL_HALT_EXE_IDLE, 0);
381 		if (err)
382 			break;
383 		err = ds_send_control(dev, CTL_RESUME_EXE, 0);
384 		if (err)
385 			break;
386 		err = ds_recv_status(dev, &st);
387 		if (err)
388 			break;
389 
390 		if ((st.status & ST_SPUA) == 0) {
391 			err = ds_send_control_mode(dev, MOD_PULSE_EN, 0);
392 			if (err)
393 				break;
394 		}
395 	} while (++count < limit);
396 
397 	return err;
398 }
399 
400 int ds_detect(struct ds_device *dev, struct ds_status *st)
401 {
402 	int err;
403 
404 	err = ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
405 	if (err)
406 		return err;
407 
408 	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, 0);
409 	if (err)
410 		return err;
411 
412 	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM | COMM_TYPE, 0x40);
413 	if (err)
414 		return err;
415 
416 	err = ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_PROG);
417 	if (err)
418 		return err;
419 
420 	err = ds_dump_status(dev, st);
421 
422 	return err;
423 }
424 
425 #endif  /*  0  */
426 
427 static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
428 {
429 	int err, count = 0;
430 
431 	do {
432 		st->status = 0;
433 		err = ds_recv_status(dev, st);
434 #if 0
435 		if (err >= 0) {
436 			int i;
437 			printk("0x%x: count=%d, status: ", dev->ep[EP_STATUS], err);
438 			for (i = 0; i < err; ++i)
439 				printk("%02x ", dev->st_buf[i]);
440 			printk("\n");
441 		}
442 #endif
443 	} while (!(st->status & ST_IDLE) && !(err < 0) && ++count < 100);
444 
445 	if (err >= 16 && st->status & ST_EPOF) {
446 		dev_info(&dev->udev->dev, "Resetting device after ST_EPOF.\n");
447 		ds_reset_device(dev);
448 		/* Always dump the device status. */
449 		count = 101;
450 	}
451 
452 	/* Dump the status for errors or if there is extended return data.
453 	 * The extended status includes new device detection (maybe someone
454 	 * can do something with it).
455 	 */
456 	if (err > 16 || count >= 100 || err < 0)
457 		ds_dump_status(dev, dev->st_buf, err);
458 
459 	/* Extended data isn't an error.  Well, a short is, but the dump
460 	 * would have already told the user that and we can't do anything
461 	 * about it in software anyway.
462 	 */
463 	if (count >= 100 || err < 0)
464 		return -1;
465 	else
466 		return 0;
467 }
468 
469 static int ds_reset(struct ds_device *dev)
470 {
471 	int err;
472 
473 	/* Other potentionally interesting flags for reset.
474 	 *
475 	 * COMM_NTF: Return result register feedback.  This could be used to
476 	 * detect some conditions such as short, alarming presence, or
477 	 * detect if a new device was detected.
478 	 *
479 	 * COMM_SE which allows SPEED_NORMAL, SPEED_FLEXIBLE, SPEED_OVERDRIVE:
480 	 * Select the data transfer rate.
481 	 */
482 	err = ds_send_control(dev, COMM_1_WIRE_RESET | COMM_IM, SPEED_NORMAL);
483 	if (err)
484 		return err;
485 
486 	return 0;
487 }
488 
489 #if 0
490 static int ds_set_speed(struct ds_device *dev, int speed)
491 {
492 	int err;
493 
494 	if (speed != SPEED_NORMAL && speed != SPEED_FLEXIBLE && speed != SPEED_OVERDRIVE)
495 		return -EINVAL;
496 
497 	if (speed != SPEED_OVERDRIVE)
498 		speed = SPEED_FLEXIBLE;
499 
500 	speed &= 0xff;
501 
502 	err = ds_send_control_mode(dev, MOD_1WIRE_SPEED, speed);
503 	if (err)
504 		return err;
505 
506 	return err;
507 }
508 #endif  /*  0  */
509 
510 static int ds_set_pullup(struct ds_device *dev, int delay)
511 {
512 	int err = 0;
513 	u8 del = 1 + (u8)(delay >> 4);
514 	/* Just storing delay would not get the trunication and roundup. */
515 	int ms = del<<4;
516 
517 	/* Enable spu_bit if a delay is set. */
518 	dev->spu_bit = delay ? COMM_SPU : 0;
519 	/* If delay is zero, it has already been disabled, if the time is
520 	 * the same as the hardware was last programmed to, there is also
521 	 * nothing more to do.  Compare with the recalculated value ms
522 	 * rather than del or delay which can have a different value.
523 	 */
524 	if (delay == 0 || ms == dev->spu_sleep)
525 		return err;
526 
527 	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del);
528 	if (err)
529 		return err;
530 
531 	dev->spu_sleep = ms;
532 
533 	return err;
534 }
535 
536 static int ds_touch_bit(struct ds_device *dev, u8 bit, u8 *tbit)
537 {
538 	int err;
539 	struct ds_status st;
540 
541 	err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | (bit ? COMM_D : 0),
542 		0);
543 	if (err)
544 		return err;
545 
546 	ds_wait_status(dev, &st);
547 
548 	err = ds_recv_data(dev, tbit, sizeof(*tbit));
549 	if (err < 0)
550 		return err;
551 
552 	return 0;
553 }
554 
555 #if 0
556 static int ds_write_bit(struct ds_device *dev, u8 bit)
557 {
558 	int err;
559 	struct ds_status st;
560 
561 	/* Set COMM_ICP to write without a readback.  Note, this will
562 	 * produce one time slot, a down followed by an up with COMM_D
563 	 * only determing the timing.
564 	 */
565 	err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | COMM_ICP |
566 		(bit ? COMM_D : 0), 0);
567 	if (err)
568 		return err;
569 
570 	ds_wait_status(dev, &st);
571 
572 	return 0;
573 }
574 #endif
575 
576 static int ds_write_byte(struct ds_device *dev, u8 byte)
577 {
578 	int err;
579 	struct ds_status st;
580 
581 	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | dev->spu_bit, byte);
582 	if (err)
583 		return err;
584 
585 	if (dev->spu_bit)
586 		msleep(dev->spu_sleep);
587 
588 	err = ds_wait_status(dev, &st);
589 	if (err)
590 		return err;
591 
592 	err = ds_recv_data(dev, &dev->byte_buf, 1);
593 	if (err < 0)
594 		return err;
595 
596 	return !(byte == dev->byte_buf);
597 }
598 
599 static int ds_read_byte(struct ds_device *dev, u8 *byte)
600 {
601 	int err;
602 	struct ds_status st;
603 
604 	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM, 0xff);
605 	if (err)
606 		return err;
607 
608 	ds_wait_status(dev, &st);
609 
610 	err = ds_recv_data(dev, byte, sizeof(*byte));
611 	if (err < 0)
612 		return err;
613 
614 	return 0;
615 }
616 
617 static int ds_read_block(struct ds_device *dev, u8 *buf, int len)
618 {
619 	struct ds_status st;
620 	int err;
621 
622 	if (len > 64*1024)
623 		return -E2BIG;
624 
625 	memset(buf, 0xFF, len);
626 
627 	err = ds_send_data(dev, buf, len);
628 	if (err < 0)
629 		return err;
630 
631 	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM, len);
632 	if (err)
633 		return err;
634 
635 	ds_wait_status(dev, &st);
636 
637 	memset(buf, 0x00, len);
638 	err = ds_recv_data(dev, buf, len);
639 
640 	return err;
641 }
642 
643 static int ds_write_block(struct ds_device *dev, u8 *buf, int len)
644 {
645 	int err;
646 	struct ds_status st;
647 
648 	err = ds_send_data(dev, buf, len);
649 	if (err < 0)
650 		return err;
651 
652 	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM | dev->spu_bit, len);
653 	if (err)
654 		return err;
655 
656 	if (dev->spu_bit)
657 		msleep(dev->spu_sleep);
658 
659 	ds_wait_status(dev, &st);
660 
661 	err = ds_recv_data(dev, buf, len);
662 	if (err < 0)
663 		return err;
664 
665 	return !(err == len);
666 }
667 
668 static void ds9490r_search(void *data, struct w1_master *master,
669 	u8 search_type, w1_slave_found_callback callback)
670 {
671 	/* When starting with an existing id, the first id returned will
672 	 * be that device (if it is still on the bus most likely).
673 	 *
674 	 * If the number of devices found is less than or equal to the
675 	 * search_limit, that number of IDs will be returned.  If there are
676 	 * more, search_limit IDs will be returned followed by a non-zero
677 	 * discrepency value.
678 	 */
679 	struct ds_device *dev = data;
680 	int err;
681 	u16 value, index;
682 	struct ds_status st;
683 	int search_limit;
684 	int found = 0;
685 	int i;
686 
687 	/* DS18b20 spec, 13.16 ms per device, 75 per second, sleep for
688 	 * discovering 8 devices (1 bulk transfer and 1/2 FIFO size) at a time.
689 	 */
690 	const unsigned long jtime = msecs_to_jiffies(1000*8/75);
691 	/* FIFO 128 bytes, bulk packet size 64, read a multiple of the
692 	 * packet size.
693 	 */
694 	const size_t bufsize = 2 * 64;
695 	u64 *buf, *found_ids;
696 
697 	buf = kmalloc(bufsize, GFP_KERNEL);
698 	if (!buf)
699 		return;
700 
701 	/*
702 	 * We are holding the bus mutex during the scan, but adding devices via the
703 	 * callback needs the bus to be unlocked. So we queue up found ids here.
704 	 */
705 	found_ids = kmalloc_array(master->max_slave_count, sizeof(u64), GFP_KERNEL);
706 	if (!found_ids) {
707 		kfree(buf);
708 		return;
709 	}
710 
711 	mutex_lock(&master->bus_mutex);
712 
713 	/* address to start searching at */
714 	if (ds_send_data(dev, (u8 *)&master->search_id, 8) < 0)
715 		goto search_out;
716 	master->search_id = 0;
717 
718 	value = COMM_SEARCH_ACCESS | COMM_IM | COMM_RST | COMM_SM | COMM_F |
719 		COMM_RTS;
720 	search_limit = master->max_slave_count;
721 	if (search_limit > 255)
722 		search_limit = 0;
723 	index = search_type | (search_limit << 8);
724 	if (ds_send_control(dev, value, index) < 0)
725 		goto search_out;
726 
727 	do {
728 		schedule_timeout(jtime);
729 
730 		err = ds_recv_status(dev, &st);
731 		if (err < 0 || err < sizeof(st))
732 			break;
733 
734 		if (st.data_in_buffer_status) {
735 			/*
736 			 * Bulk in can receive partial ids, but when it does
737 			 * they fail crc and will be discarded anyway.
738 			 * That has only been seen when status in buffer
739 			 * is 0 and bulk is read anyway, so don't read
740 			 * bulk without first checking if status says there
741 			 * is data to read.
742 			 */
743 			err = ds_recv_data(dev, (u8 *)buf, bufsize);
744 			if (err < 0)
745 				break;
746 			for (i = 0; i < err/8; ++i) {
747 				found_ids[found++] = buf[i];
748 				/*
749 				 * can't know if there will be a discrepancy
750 				 * value after until the next id
751 				 */
752 				if (found == search_limit) {
753 					master->search_id = buf[i];
754 					break;
755 				}
756 			}
757 		}
758 
759 		if (test_bit(W1_ABORT_SEARCH, &master->flags))
760 			break;
761 	} while (!(st.status & (ST_IDLE | ST_HALT)));
762 
763 	/* only continue the search if some weren't found */
764 	if (found <= search_limit) {
765 		master->search_id = 0;
766 	} else if (!test_bit(W1_WARN_MAX_COUNT, &master->flags)) {
767 		/*
768 		 * Only max_slave_count will be scanned in a search,
769 		 * but it will start where it left off next search
770 		 * until all ids are identified and then it will start
771 		 * over.  A continued search will report the previous
772 		 * last id as the first id (provided it is still on the
773 		 * bus).
774 		 */
775 		dev_info(&dev->udev->dev, "%s: max_slave_count %d reached, "
776 			"will continue next search.\n", __func__,
777 			master->max_slave_count);
778 		set_bit(W1_WARN_MAX_COUNT, &master->flags);
779 	}
780 
781 search_out:
782 	mutex_unlock(&master->bus_mutex);
783 	kfree(buf);
784 
785 	for (i = 0; i < found; i++) /* run callback for all queued up IDs */
786 		callback(master, found_ids[i]);
787 	kfree(found_ids);
788 }
789 
790 #if 0
791 /*
792  * FIXME: if this disabled code is ever used in the future all ds_send_data()
793  * calls must be changed to use a DMAable buffer.
794  */
795 static int ds_match_access(struct ds_device *dev, u64 init)
796 {
797 	int err;
798 	struct ds_status st;
799 
800 	err = ds_send_data(dev, (unsigned char *)&init, sizeof(init));
801 	if (err)
802 		return err;
803 
804 	ds_wait_status(dev, &st);
805 
806 	err = ds_send_control(dev, COMM_MATCH_ACCESS | COMM_IM | COMM_RST, 0x0055);
807 	if (err)
808 		return err;
809 
810 	ds_wait_status(dev, &st);
811 
812 	return 0;
813 }
814 
815 static int ds_set_path(struct ds_device *dev, u64 init)
816 {
817 	int err;
818 	struct ds_status st;
819 	u8 buf[9];
820 
821 	memcpy(buf, &init, 8);
822 	buf[8] = BRANCH_MAIN;
823 
824 	err = ds_send_data(dev, buf, sizeof(buf));
825 	if (err)
826 		return err;
827 
828 	ds_wait_status(dev, &st);
829 
830 	err = ds_send_control(dev, COMM_SET_PATH | COMM_IM | COMM_RST, 0);
831 	if (err)
832 		return err;
833 
834 	ds_wait_status(dev, &st);
835 
836 	return 0;
837 }
838 
839 #endif  /*  0  */
840 
841 static u8 ds9490r_touch_bit(void *data, u8 bit)
842 {
843 	struct ds_device *dev = data;
844 
845 	if (ds_touch_bit(dev, bit, &dev->byte_buf))
846 		return 0;
847 
848 	return dev->byte_buf;
849 }
850 
851 #if 0
852 static void ds9490r_write_bit(void *data, u8 bit)
853 {
854 	struct ds_device *dev = data;
855 
856 	ds_write_bit(dev, bit);
857 }
858 
859 static u8 ds9490r_read_bit(void *data)
860 {
861 	struct ds_device *dev = data;
862 	int err;
863 
864 	err = ds_touch_bit(dev, 1, &dev->byte_buf);
865 	if (err)
866 		return 0;
867 
868 	return dev->byte_buf & 1;
869 }
870 #endif
871 
872 static void ds9490r_write_byte(void *data, u8 byte)
873 {
874 	struct ds_device *dev = data;
875 
876 	ds_write_byte(dev, byte);
877 }
878 
879 static u8 ds9490r_read_byte(void *data)
880 {
881 	struct ds_device *dev = data;
882 	int err;
883 
884 	err = ds_read_byte(dev, &dev->byte_buf);
885 	if (err)
886 		return 0;
887 
888 	return dev->byte_buf;
889 }
890 
891 static void ds9490r_write_block(void *data, const u8 *buf, int len)
892 {
893 	struct ds_device *dev = data;
894 	u8 *tbuf;
895 
896 	if (len <= 0)
897 		return;
898 
899 	tbuf = kmemdup(buf, len, GFP_KERNEL);
900 	if (!tbuf)
901 		return;
902 
903 	ds_write_block(dev, tbuf, len);
904 
905 	kfree(tbuf);
906 }
907 
908 static u8 ds9490r_read_block(void *data, u8 *buf, int len)
909 {
910 	struct ds_device *dev = data;
911 	int err;
912 	u8 *tbuf;
913 
914 	if (len <= 0)
915 		return 0;
916 
917 	tbuf = kmalloc(len, GFP_KERNEL);
918 	if (!tbuf)
919 		return 0;
920 
921 	err = ds_read_block(dev, tbuf, len);
922 	if (err >= 0)
923 		memcpy(buf, tbuf, len);
924 
925 	kfree(tbuf);
926 
927 	return err >= 0 ? len : 0;
928 }
929 
930 static u8 ds9490r_reset(void *data)
931 {
932 	struct ds_device *dev = data;
933 	int err;
934 
935 	err = ds_reset(dev);
936 	if (err)
937 		return 1;
938 
939 	return 0;
940 }
941 
942 static u8 ds9490r_set_pullup(void *data, int delay)
943 {
944 	struct ds_device *dev = data;
945 
946 	if (ds_set_pullup(dev, delay))
947 		return 1;
948 
949 	return 0;
950 }
951 
952 static int ds_w1_init(struct ds_device *dev)
953 {
954 	memset(&dev->master, 0, sizeof(struct w1_bus_master));
955 
956 	/* Reset the device as it can be in a bad state.
957 	 * This is necessary because a block write will wait for data
958 	 * to be placed in the output buffer and block any later
959 	 * commands which will keep accumulating and the device will
960 	 * not be idle.  Another case is removing the ds2490 module
961 	 * while a bus search is in progress, somehow a few commands
962 	 * get through, but the input transfers fail leaving data in
963 	 * the input buffer.  This will cause the next read to fail
964 	 * see the note in ds_recv_data.
965 	 */
966 	ds_reset_device(dev);
967 
968 	dev->master.data	= dev;
969 	dev->master.touch_bit	= &ds9490r_touch_bit;
970 	/* read_bit and write_bit in w1_bus_master are expected to set and
971 	 * sample the line level.  For write_bit that means it is expected to
972 	 * set it to that value and leave it there.  ds2490 only supports an
973 	 * individual time slot at the lowest level.  The requirement from
974 	 * pulling the bus state down to reading the state is 15us, something
975 	 * that isn't realistic on the USB bus anyway.
976 	dev->master.read_bit	= &ds9490r_read_bit;
977 	dev->master.write_bit	= &ds9490r_write_bit;
978 	*/
979 	dev->master.read_byte	= &ds9490r_read_byte;
980 	dev->master.write_byte	= &ds9490r_write_byte;
981 	dev->master.read_block	= &ds9490r_read_block;
982 	dev->master.write_block	= &ds9490r_write_block;
983 	dev->master.reset_bus	= &ds9490r_reset;
984 	dev->master.set_pullup	= &ds9490r_set_pullup;
985 	dev->master.search	= &ds9490r_search;
986 
987 	return w1_add_master_device(&dev->master);
988 }
989 
990 static void ds_w1_fini(struct ds_device *dev)
991 {
992 	w1_remove_master_device(&dev->master);
993 }
994 
995 static int ds_probe(struct usb_interface *intf,
996 		    const struct usb_device_id *udev_id)
997 {
998 	struct usb_device *udev = interface_to_usbdev(intf);
999 	struct usb_endpoint_descriptor *endpoint;
1000 	struct usb_host_interface *iface_desc;
1001 	struct ds_device *dev;
1002 	int i, err, alt;
1003 
1004 	dev = kzalloc(sizeof(struct ds_device), GFP_KERNEL);
1005 	if (!dev)
1006 		return -ENOMEM;
1007 
1008 	dev->udev = usb_get_dev(udev);
1009 	if (!dev->udev) {
1010 		err = -ENOMEM;
1011 		goto err_out_free;
1012 	}
1013 	memset(dev->ep, 0, sizeof(dev->ep));
1014 
1015 	usb_set_intfdata(intf, dev);
1016 
1017 	err = usb_reset_configuration(dev->udev);
1018 	if (err) {
1019 		dev_err(&dev->udev->dev,
1020 			"Failed to reset configuration: err=%d.\n", err);
1021 		goto err_out_clear;
1022 	}
1023 
1024 	/* alternative 3, 1ms interrupt (greatly speeds search), 64 byte bulk */
1025 	alt = 3;
1026 	err = usb_set_interface(dev->udev,
1027 		intf->cur_altsetting->desc.bInterfaceNumber, alt);
1028 	if (err) {
1029 		dev_err(&dev->udev->dev, "Failed to set alternative setting %d "
1030 			"for %d interface: err=%d.\n", alt,
1031 			intf->cur_altsetting->desc.bInterfaceNumber, err);
1032 		goto err_out_clear;
1033 	}
1034 
1035 	iface_desc = intf->cur_altsetting;
1036 	if (iface_desc->desc.bNumEndpoints != NUM_EP-1) {
1037 		dev_err(&dev->udev->dev, "Num endpoints=%d. It is not DS9490R.\n",
1038 			iface_desc->desc.bNumEndpoints);
1039 		err = -EINVAL;
1040 		goto err_out_clear;
1041 	}
1042 
1043 	/*
1044 	 * This loop doesn'd show control 0 endpoint,
1045 	 * so we will fill only 1-3 endpoints entry.
1046 	 */
1047 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
1048 		endpoint = &iface_desc->endpoint[i].desc;
1049 
1050 		dev->ep[i+1] = endpoint->bEndpointAddress;
1051 #if 0
1052 		printk("%d: addr=%x, size=%d, dir=%s, type=%x\n",
1053 			i, endpoint->bEndpointAddress, le16_to_cpu(endpoint->wMaxPacketSize),
1054 			(endpoint->bEndpointAddress & USB_DIR_IN)?"IN":"OUT",
1055 			endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK);
1056 #endif
1057 	}
1058 
1059 	err = ds_w1_init(dev);
1060 	if (err)
1061 		goto err_out_clear;
1062 
1063 	mutex_lock(&ds_mutex);
1064 	list_add_tail(&dev->ds_entry, &ds_devices);
1065 	mutex_unlock(&ds_mutex);
1066 
1067 	return 0;
1068 
1069 err_out_clear:
1070 	usb_set_intfdata(intf, NULL);
1071 	usb_put_dev(dev->udev);
1072 err_out_free:
1073 	kfree(dev);
1074 	return err;
1075 }
1076 
1077 static void ds_disconnect(struct usb_interface *intf)
1078 {
1079 	struct ds_device *dev;
1080 
1081 	dev = usb_get_intfdata(intf);
1082 	if (!dev)
1083 		return;
1084 
1085 	mutex_lock(&ds_mutex);
1086 	list_del(&dev->ds_entry);
1087 	mutex_unlock(&ds_mutex);
1088 
1089 	ds_w1_fini(dev);
1090 
1091 	usb_set_intfdata(intf, NULL);
1092 
1093 	usb_put_dev(dev->udev);
1094 	kfree(dev);
1095 }
1096 
1097 static const struct usb_device_id ds_id_table[] = {
1098 	{ USB_DEVICE(0x04fa, 0x2490) },
1099 	{ },
1100 };
1101 MODULE_DEVICE_TABLE(usb, ds_id_table);
1102 
1103 static struct usb_driver ds_driver = {
1104 	.name =		"DS9490R",
1105 	.probe =	ds_probe,
1106 	.disconnect =	ds_disconnect,
1107 	.id_table =	ds_id_table,
1108 };
1109 module_usb_driver(ds_driver);
1110 
1111 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
1112 MODULE_DESCRIPTION("DS2490 USB <-> W1 bus master driver (DS9490*)");
1113 MODULE_LICENSE("GPL");
1114