xref: /linux/drivers/w1/slaves/w1_ds28e17.c (revision 1ac731c529cd4d6adbce134754b51ff7d822b145)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *	w1_ds28e17.c - w1 family 19 (DS28E17) driver
4  *
5  * Copyright (c) 2016 Jan Kandziora <jjj@gmx.de>
6  */
7 
8 #include <linux/crc16.h>
9 #include <linux/delay.h>
10 #include <linux/device.h>
11 #include <linux/i2c.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/slab.h>
16 #include <linux/types.h>
17 #include <linux/uaccess.h>
18 
19 #define CRC16_INIT 0
20 
21 #include <linux/w1.h>
22 
23 #define W1_FAMILY_DS28E17 0x19
24 
25 /* Module setup. */
26 MODULE_LICENSE("GPL v2");
27 MODULE_AUTHOR("Jan Kandziora <jjj@gmx.de>");
28 MODULE_DESCRIPTION("w1 family 19 driver for DS28E17, 1-wire to I2C master bridge");
29 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E17));
30 
31 
32 /* Default I2C speed to be set when a DS28E17 is detected. */
33 static int i2c_speed = 100;
34 module_param_named(speed, i2c_speed, int, 0600);
35 MODULE_PARM_DESC(speed, "Default I2C speed to be set when a DS28E17 is detected");
36 
37 /* Default I2C stretch value to be set when a DS28E17 is detected. */
38 static char i2c_stretch = 1;
39 module_param_named(stretch, i2c_stretch, byte, 0600);
40 MODULE_PARM_DESC(stretch, "Default I2C stretch value to be set when a DS28E17 is detected");
41 
42 /* DS28E17 device command codes. */
43 #define W1_F19_WRITE_DATA_WITH_STOP      0x4B
44 #define W1_F19_WRITE_DATA_NO_STOP        0x5A
45 #define W1_F19_WRITE_DATA_ONLY           0x69
46 #define W1_F19_WRITE_DATA_ONLY_WITH_STOP 0x78
47 #define W1_F19_READ_DATA_WITH_STOP       0x87
48 #define W1_F19_WRITE_READ_DATA_WITH_STOP 0x2D
49 #define W1_F19_WRITE_CONFIGURATION       0xD2
50 #define W1_F19_READ_CONFIGURATION        0xE1
51 #define W1_F19_ENABLE_SLEEP_MODE         0x1E
52 #define W1_F19_READ_DEVICE_REVISION      0xC4
53 
54 /* DS28E17 status bits */
55 #define W1_F19_STATUS_CRC     0x01
56 #define W1_F19_STATUS_ADDRESS 0x02
57 #define W1_F19_STATUS_START   0x08
58 
59 /*
60  * Maximum number of I2C bytes to transfer within one CRC16 protected onewire
61  * command.
62  */
63 #define W1_F19_WRITE_DATA_LIMIT 255
64 
65 /* Maximum number of I2C bytes to read with one onewire command. */
66 #define W1_F19_READ_DATA_LIMIT 255
67 
68 /* Constants for calculating the busy sleep. */
69 #define W1_F19_BUSY_TIMEBASES { 90, 23, 10 }
70 #define W1_F19_BUSY_GRATUITY  1000
71 
72 /* Number of checks for the busy flag before timeout. */
73 #define W1_F19_BUSY_CHECKS 1000
74 
75 
76 /* Slave specific data. */
77 struct w1_f19_data {
78 	u8 speed;
79 	u8 stretch;
80 	struct i2c_adapter adapter;
81 };
82 
83 
84 /* Wait a while until the busy flag clears. */
w1_f19_i2c_busy_wait(struct w1_slave * sl,size_t count)85 static int w1_f19_i2c_busy_wait(struct w1_slave *sl, size_t count)
86 {
87 	const unsigned long timebases[3] = W1_F19_BUSY_TIMEBASES;
88 	struct w1_f19_data *data = sl->family_data;
89 	unsigned int checks;
90 
91 	/* Check the busy flag first in any case.*/
92 	if (w1_touch_bit(sl->master, 1) == 0)
93 		return 0;
94 
95 	/*
96 	 * Do a generously long sleep in the beginning,
97 	 * as we have to wait at least this time for all
98 	 * the I2C bytes at the given speed to be transferred.
99 	 */
100 	usleep_range(timebases[data->speed] * (data->stretch) * count,
101 		timebases[data->speed] * (data->stretch) * count
102 		+ W1_F19_BUSY_GRATUITY);
103 
104 	/* Now continusly check the busy flag sent by the DS28E17. */
105 	checks = W1_F19_BUSY_CHECKS;
106 	while ((checks--) > 0) {
107 		/* Return success if the busy flag is cleared. */
108 		if (w1_touch_bit(sl->master, 1) == 0)
109 			return 0;
110 
111 		/* Wait one non-streched byte timeslot. */
112 		udelay(timebases[data->speed]);
113 	}
114 
115 	/* Timeout. */
116 	dev_warn(&sl->dev, "busy timeout\n");
117 	return -ETIMEDOUT;
118 }
119 
120 
121 /* Utility function: result. */
w1_f19_error(struct w1_slave * sl,u8 w1_buf[])122 static size_t w1_f19_error(struct w1_slave *sl, u8 w1_buf[])
123 {
124 	/* Warnings. */
125 	if (w1_buf[0] & W1_F19_STATUS_CRC)
126 		dev_warn(&sl->dev, "crc16 mismatch\n");
127 	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
128 		dev_warn(&sl->dev, "i2c device not responding\n");
129 	if ((w1_buf[0] & (W1_F19_STATUS_CRC | W1_F19_STATUS_ADDRESS)) == 0
130 			&& w1_buf[1] != 0) {
131 		dev_warn(&sl->dev, "i2c short write, %d bytes not acknowledged\n",
132 			w1_buf[1]);
133 	}
134 
135 	/* Check error conditions. */
136 	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
137 		return -ENXIO;
138 	if (w1_buf[0] & W1_F19_STATUS_START)
139 		return -EAGAIN;
140 	if (w1_buf[0] != 0 || w1_buf[1] != 0)
141 		return -EIO;
142 
143 	/* All ok. */
144 	return 0;
145 }
146 
147 
148 /* Utility function: write data to I2C slave, single chunk. */
__w1_f19_i2c_write(struct w1_slave * sl,const u8 * command,size_t command_count,const u8 * buffer,size_t count)149 static int __w1_f19_i2c_write(struct w1_slave *sl,
150 	const u8 *command, size_t command_count,
151 	const u8 *buffer, size_t count)
152 {
153 	u16 crc;
154 	int error;
155 	u8 w1_buf[2];
156 
157 	/* Send command and I2C data to DS28E17. */
158 	crc = crc16(CRC16_INIT, command, command_count);
159 	w1_write_block(sl->master, command, command_count);
160 
161 	w1_buf[0] = count;
162 	crc = crc16(crc, w1_buf, 1);
163 	w1_write_8(sl->master, w1_buf[0]);
164 
165 	crc = crc16(crc, buffer, count);
166 	w1_write_block(sl->master, buffer, count);
167 
168 	w1_buf[0] = ~(crc & 0xFF);
169 	w1_buf[1] = ~((crc >> 8) & 0xFF);
170 	w1_write_block(sl->master, w1_buf, 2);
171 
172 	/* Wait until busy flag clears (or timeout). */
173 	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
174 		return -ETIMEDOUT;
175 
176 	/* Read status from DS28E17. */
177 	w1_read_block(sl->master, w1_buf, 2);
178 
179 	/* Check error conditions. */
180 	error = w1_f19_error(sl, w1_buf);
181 	if (error < 0)
182 		return error;
183 
184 	/* Return number of bytes written. */
185 	return count;
186 }
187 
188 
189 /* Write data to I2C slave. */
w1_f19_i2c_write(struct w1_slave * sl,u16 i2c_address,const u8 * buffer,size_t count,bool stop)190 static int w1_f19_i2c_write(struct w1_slave *sl, u16 i2c_address,
191 	const u8 *buffer, size_t count, bool stop)
192 {
193 	int result;
194 	int remaining = count;
195 	const u8 *p;
196 	u8 command[2];
197 
198 	/* Check input. */
199 	if (count == 0)
200 		return -EOPNOTSUPP;
201 
202 	/* Check whether we need multiple commands. */
203 	if (count <= W1_F19_WRITE_DATA_LIMIT) {
204 		/*
205 		 * Small data amount. Data can be sent with
206 		 * a single onewire command.
207 		 */
208 
209 		/* Send all data to DS28E17. */
210 		command[0] = (stop ? W1_F19_WRITE_DATA_WITH_STOP
211 			: W1_F19_WRITE_DATA_NO_STOP);
212 		command[1] = i2c_address << 1;
213 		result = __w1_f19_i2c_write(sl, command, 2, buffer, count);
214 	} else {
215 		/* Large data amount. Data has to be sent in multiple chunks. */
216 
217 		/* Send first chunk to DS28E17. */
218 		p = buffer;
219 		command[0] = W1_F19_WRITE_DATA_NO_STOP;
220 		command[1] = i2c_address << 1;
221 		result = __w1_f19_i2c_write(sl, command, 2, p,
222 			W1_F19_WRITE_DATA_LIMIT);
223 		if (result < 0)
224 			return result;
225 
226 		/* Resume to same DS28E17. */
227 		if (w1_reset_resume_command(sl->master))
228 			return -EIO;
229 
230 		/* Next data chunk. */
231 		p += W1_F19_WRITE_DATA_LIMIT;
232 		remaining -= W1_F19_WRITE_DATA_LIMIT;
233 
234 		while (remaining > W1_F19_WRITE_DATA_LIMIT) {
235 			/* Send intermediate chunk to DS28E17. */
236 			command[0] = W1_F19_WRITE_DATA_ONLY;
237 			result = __w1_f19_i2c_write(sl, command, 1, p,
238 					W1_F19_WRITE_DATA_LIMIT);
239 			if (result < 0)
240 				return result;
241 
242 			/* Resume to same DS28E17. */
243 			if (w1_reset_resume_command(sl->master))
244 				return -EIO;
245 
246 			/* Next data chunk. */
247 			p += W1_F19_WRITE_DATA_LIMIT;
248 			remaining -= W1_F19_WRITE_DATA_LIMIT;
249 		}
250 
251 		/* Send final chunk to DS28E17. */
252 		command[0] = (stop ? W1_F19_WRITE_DATA_ONLY_WITH_STOP
253 			: W1_F19_WRITE_DATA_ONLY);
254 		result = __w1_f19_i2c_write(sl, command, 1, p, remaining);
255 	}
256 
257 	return result;
258 }
259 
260 
261 /* Read data from I2C slave. */
w1_f19_i2c_read(struct w1_slave * sl,u16 i2c_address,u8 * buffer,size_t count)262 static int w1_f19_i2c_read(struct w1_slave *sl, u16 i2c_address,
263 	u8 *buffer, size_t count)
264 {
265 	u16 crc;
266 	int error;
267 	u8 w1_buf[5];
268 
269 	/* Check input. */
270 	if (count == 0)
271 		return -EOPNOTSUPP;
272 
273 	/* Send command to DS28E17. */
274 	w1_buf[0] = W1_F19_READ_DATA_WITH_STOP;
275 	w1_buf[1] = i2c_address << 1 | 0x01;
276 	w1_buf[2] = count;
277 	crc = crc16(CRC16_INIT, w1_buf, 3);
278 	w1_buf[3] = ~(crc & 0xFF);
279 	w1_buf[4] = ~((crc >> 8) & 0xFF);
280 	w1_write_block(sl->master, w1_buf, 5);
281 
282 	/* Wait until busy flag clears (or timeout). */
283 	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
284 		return -ETIMEDOUT;
285 
286 	/* Read status from DS28E17. */
287 	w1_buf[0] = w1_read_8(sl->master);
288 	w1_buf[1] = 0;
289 
290 	/* Check error conditions. */
291 	error = w1_f19_error(sl, w1_buf);
292 	if (error < 0)
293 		return error;
294 
295 	/* Read received I2C data from DS28E17. */
296 	return w1_read_block(sl->master, buffer, count);
297 }
298 
299 
300 /* Write to, then read data from I2C slave. */
w1_f19_i2c_write_read(struct w1_slave * sl,u16 i2c_address,const u8 * wbuffer,size_t wcount,u8 * rbuffer,size_t rcount)301 static int w1_f19_i2c_write_read(struct w1_slave *sl, u16 i2c_address,
302 	const u8 *wbuffer, size_t wcount, u8 *rbuffer, size_t rcount)
303 {
304 	u16 crc;
305 	int error;
306 	u8 w1_buf[3];
307 
308 	/* Check input. */
309 	if (wcount == 0 || rcount == 0)
310 		return -EOPNOTSUPP;
311 
312 	/* Send command and I2C data to DS28E17. */
313 	w1_buf[0] = W1_F19_WRITE_READ_DATA_WITH_STOP;
314 	w1_buf[1] = i2c_address << 1;
315 	w1_buf[2] = wcount;
316 	crc = crc16(CRC16_INIT, w1_buf, 3);
317 	w1_write_block(sl->master, w1_buf, 3);
318 
319 	crc = crc16(crc, wbuffer, wcount);
320 	w1_write_block(sl->master, wbuffer, wcount);
321 
322 	w1_buf[0] = rcount;
323 	crc = crc16(crc, w1_buf, 1);
324 	w1_buf[1] = ~(crc & 0xFF);
325 	w1_buf[2] = ~((crc >> 8) & 0xFF);
326 	w1_write_block(sl->master, w1_buf, 3);
327 
328 	/* Wait until busy flag clears (or timeout). */
329 	if (w1_f19_i2c_busy_wait(sl, wcount + rcount + 2) < 0)
330 		return -ETIMEDOUT;
331 
332 	/* Read status from DS28E17. */
333 	w1_read_block(sl->master, w1_buf, 2);
334 
335 	/* Check error conditions. */
336 	error = w1_f19_error(sl, w1_buf);
337 	if (error < 0)
338 		return error;
339 
340 	/* Read received I2C data from DS28E17. */
341 	return w1_read_block(sl->master, rbuffer, rcount);
342 }
343 
344 
345 /* Do an I2C master transfer. */
w1_f19_i2c_master_transfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)346 static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
347 	struct i2c_msg *msgs, int num)
348 {
349 	struct w1_slave *sl = (struct w1_slave *) adapter->algo_data;
350 	int i = 0;
351 	int result = 0;
352 
353 	/* Start onewire transaction. */
354 	mutex_lock(&sl->master->bus_mutex);
355 
356 	/* Select DS28E17. */
357 	if (w1_reset_select_slave(sl)) {
358 		i = -EIO;
359 		goto error;
360 	}
361 
362 	/* Loop while there are still messages to transfer. */
363 	while (i < num) {
364 		/*
365 		 * Check for special case: Small write followed
366 		 * by read to same I2C device.
367 		 */
368 		if (i < (num-1)
369 			&& msgs[i].addr == msgs[i+1].addr
370 			&& !(msgs[i].flags & I2C_M_RD)
371 			&& (msgs[i+1].flags & I2C_M_RD)
372 			&& (msgs[i].len <= W1_F19_WRITE_DATA_LIMIT)) {
373 			/*
374 			 * The DS28E17 has a combined transfer
375 			 * for small write+read.
376 			 */
377 			result = w1_f19_i2c_write_read(sl, msgs[i].addr,
378 				msgs[i].buf, msgs[i].len,
379 				msgs[i+1].buf, msgs[i+1].len);
380 			if (result < 0) {
381 				i = result;
382 				goto error;
383 			}
384 
385 			/*
386 			 * Check if we should interpret the read data
387 			 * as a length byte. The DS28E17 unfortunately
388 			 * has no read without stop, so we can just do
389 			 * another simple read in that case.
390 			 */
391 			if (msgs[i+1].flags & I2C_M_RECV_LEN) {
392 				result = w1_f19_i2c_read(sl, msgs[i+1].addr,
393 					&(msgs[i+1].buf[1]), msgs[i+1].buf[0]);
394 				if (result < 0) {
395 					i = result;
396 					goto error;
397 				}
398 			}
399 
400 			/* Eat up read message, too. */
401 			i++;
402 		} else if (msgs[i].flags & I2C_M_RD) {
403 			/* Read transfer. */
404 			result = w1_f19_i2c_read(sl, msgs[i].addr,
405 				msgs[i].buf, msgs[i].len);
406 			if (result < 0) {
407 				i = result;
408 				goto error;
409 			}
410 
411 			/*
412 			 * Check if we should interpret the read data
413 			 * as a length byte. The DS28E17 unfortunately
414 			 * has no read without stop, so we can just do
415 			 * another simple read in that case.
416 			 */
417 			if (msgs[i].flags & I2C_M_RECV_LEN) {
418 				result = w1_f19_i2c_read(sl,
419 					msgs[i].addr,
420 					&(msgs[i].buf[1]),
421 					msgs[i].buf[0]);
422 				if (result < 0) {
423 					i = result;
424 					goto error;
425 				}
426 			}
427 		} else {
428 			/*
429 			 * Write transfer.
430 			 * Stop condition only for last
431 			 * transfer.
432 			 */
433 			result = w1_f19_i2c_write(sl,
434 				msgs[i].addr,
435 				msgs[i].buf,
436 				msgs[i].len,
437 				i == (num-1));
438 			if (result < 0) {
439 				i = result;
440 				goto error;
441 			}
442 		}
443 
444 		/* Next message. */
445 		i++;
446 
447 		/* Are there still messages to send/receive? */
448 		if (i < num) {
449 			/* Yes. Resume to same DS28E17. */
450 			if (w1_reset_resume_command(sl->master)) {
451 				i = -EIO;
452 				goto error;
453 			}
454 		}
455 	}
456 
457 error:
458 	/* End onewire transaction. */
459 	mutex_unlock(&sl->master->bus_mutex);
460 
461 	/* Return number of messages processed or error. */
462 	return i;
463 }
464 
465 
466 /* Get I2C adapter functionality. */
w1_f19_i2c_functionality(struct i2c_adapter * adapter)467 static u32 w1_f19_i2c_functionality(struct i2c_adapter *adapter)
468 {
469 	/*
470 	 * Plain I2C functions only.
471 	 * SMBus is emulated by the kernel's I2C layer.
472 	 * No "I2C_FUNC_SMBUS_QUICK"
473 	 * No "I2C_FUNC_SMBUS_READ_BLOCK_DATA"
474 	 * No "I2C_FUNC_SMBUS_BLOCK_PROC_CALL"
475 	 */
476 	return I2C_FUNC_I2C |
477 		I2C_FUNC_SMBUS_BYTE |
478 		I2C_FUNC_SMBUS_BYTE_DATA |
479 		I2C_FUNC_SMBUS_WORD_DATA |
480 		I2C_FUNC_SMBUS_PROC_CALL |
481 		I2C_FUNC_SMBUS_WRITE_BLOCK_DATA |
482 		I2C_FUNC_SMBUS_I2C_BLOCK |
483 		I2C_FUNC_SMBUS_PEC;
484 }
485 
486 
487 /* I2C adapter quirks. */
488 static const struct i2c_adapter_quirks w1_f19_i2c_adapter_quirks = {
489 	.max_read_len = W1_F19_READ_DATA_LIMIT,
490 };
491 
492 /* I2C algorithm. */
493 static const struct i2c_algorithm w1_f19_i2c_algorithm = {
494 	.master_xfer    = w1_f19_i2c_master_transfer,
495 	.functionality  = w1_f19_i2c_functionality,
496 };
497 
498 
499 /* Read I2C speed from DS28E17. */
w1_f19_get_i2c_speed(struct w1_slave * sl)500 static int w1_f19_get_i2c_speed(struct w1_slave *sl)
501 {
502 	struct w1_f19_data *data = sl->family_data;
503 	int result = -EIO;
504 
505 	/* Start onewire transaction. */
506 	mutex_lock(&sl->master->bus_mutex);
507 
508 	/* Select slave. */
509 	if (w1_reset_select_slave(sl))
510 		goto error;
511 
512 	/* Read slave configuration byte. */
513 	w1_write_8(sl->master, W1_F19_READ_CONFIGURATION);
514 	result = w1_read_8(sl->master);
515 	if (result < 0 || result > 2) {
516 		result = -EIO;
517 		goto error;
518 	}
519 
520 	/* Update speed in slave specific data. */
521 	data->speed = result;
522 
523 error:
524 	/* End onewire transaction. */
525 	mutex_unlock(&sl->master->bus_mutex);
526 
527 	return result;
528 }
529 
530 
531 /* Set I2C speed on DS28E17. */
__w1_f19_set_i2c_speed(struct w1_slave * sl,u8 speed)532 static int __w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
533 {
534 	struct w1_f19_data *data = sl->family_data;
535 	const int i2c_speeds[3] = { 100, 400, 900 };
536 	u8 w1_buf[2];
537 
538 	/* Select slave. */
539 	if (w1_reset_select_slave(sl))
540 		return -EIO;
541 
542 	w1_buf[0] = W1_F19_WRITE_CONFIGURATION;
543 	w1_buf[1] = speed;
544 	w1_write_block(sl->master, w1_buf, 2);
545 
546 	/* Update speed in slave specific data. */
547 	data->speed = speed;
548 
549 	dev_info(&sl->dev, "i2c speed set to %d kBaud\n", i2c_speeds[speed]);
550 
551 	return 0;
552 }
553 
w1_f19_set_i2c_speed(struct w1_slave * sl,u8 speed)554 static int w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
555 {
556 	int result;
557 
558 	/* Start onewire transaction. */
559 	mutex_lock(&sl->master->bus_mutex);
560 
561 	/* Set I2C speed on DS28E17. */
562 	result = __w1_f19_set_i2c_speed(sl, speed);
563 
564 	/* End onewire transaction. */
565 	mutex_unlock(&sl->master->bus_mutex);
566 
567 	return result;
568 }
569 
570 
571 /* Sysfs attributes. */
572 
573 /* I2C speed attribute for a single chip. */
speed_show(struct device * dev,struct device_attribute * attr,char * buf)574 static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
575 			     char *buf)
576 {
577 	struct w1_slave *sl = dev_to_w1_slave(dev);
578 	int result;
579 
580 	/* Read current speed from slave. Updates data->speed. */
581 	result = w1_f19_get_i2c_speed(sl);
582 	if (result < 0)
583 		return result;
584 
585 	/* Return current speed value. */
586 	return sprintf(buf, "%d\n", result);
587 }
588 
speed_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)589 static ssize_t speed_store(struct device *dev, struct device_attribute *attr,
590 			      const char *buf, size_t count)
591 {
592 	struct w1_slave *sl = dev_to_w1_slave(dev);
593 	int error;
594 
595 	/* Valid values are: "100", "400", "900" */
596 	if (count < 3 || count > 4 || !buf)
597 		return -EINVAL;
598 	if (count == 4 && buf[3] != '\n')
599 		return -EINVAL;
600 	if (buf[1] != '0' || buf[2] != '0')
601 		return -EINVAL;
602 
603 	/* Set speed on slave. */
604 	switch (buf[0]) {
605 	case '1':
606 		error = w1_f19_set_i2c_speed(sl, 0);
607 		break;
608 	case '4':
609 		error = w1_f19_set_i2c_speed(sl, 1);
610 		break;
611 	case '9':
612 		error = w1_f19_set_i2c_speed(sl, 2);
613 		break;
614 	default:
615 		return -EINVAL;
616 	}
617 
618 	if (error < 0)
619 		return error;
620 
621 	/* Return bytes written. */
622 	return count;
623 }
624 
625 static DEVICE_ATTR_RW(speed);
626 
627 
628 /* Busy stretch attribute for a single chip. */
stretch_show(struct device * dev,struct device_attribute * attr,char * buf)629 static ssize_t stretch_show(struct device *dev, struct device_attribute *attr,
630 			     char *buf)
631 {
632 	struct w1_slave *sl = dev_to_w1_slave(dev);
633 	struct w1_f19_data *data = sl->family_data;
634 
635 	/* Return current stretch value. */
636 	return sprintf(buf, "%d\n", data->stretch);
637 }
638 
stretch_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)639 static ssize_t stretch_store(struct device *dev, struct device_attribute *attr,
640 			      const char *buf, size_t count)
641 {
642 	struct w1_slave *sl = dev_to_w1_slave(dev);
643 	struct w1_f19_data *data = sl->family_data;
644 
645 	/* Valid values are '1' to '9' */
646 	if (count < 1 || count > 2 || !buf)
647 		return -EINVAL;
648 	if (count == 2 && buf[1] != '\n')
649 		return -EINVAL;
650 	if (buf[0] < '1' || buf[0] > '9')
651 		return -EINVAL;
652 
653 	/* Set busy stretch value. */
654 	data->stretch = buf[0] & 0x0F;
655 
656 	/* Return bytes written. */
657 	return count;
658 }
659 
660 static DEVICE_ATTR_RW(stretch);
661 
662 
663 /* All attributes. */
664 static struct attribute *w1_f19_attrs[] = {
665 	&dev_attr_speed.attr,
666 	&dev_attr_stretch.attr,
667 	NULL,
668 };
669 
670 static const struct attribute_group w1_f19_group = {
671 	.attrs		= w1_f19_attrs,
672 };
673 
674 static const struct attribute_group *w1_f19_groups[] = {
675 	&w1_f19_group,
676 	NULL,
677 };
678 
679 
680 /* Slave add and remove functions. */
w1_f19_add_slave(struct w1_slave * sl)681 static int w1_f19_add_slave(struct w1_slave *sl)
682 {
683 	struct w1_f19_data *data = NULL;
684 
685 	/* Allocate memory for slave specific data. */
686 	data = devm_kzalloc(&sl->dev, sizeof(*data), GFP_KERNEL);
687 	if (!data)
688 		return -ENOMEM;
689 	sl->family_data = data;
690 
691 	/* Setup default I2C speed on slave. */
692 	switch (i2c_speed) {
693 	case 100:
694 		__w1_f19_set_i2c_speed(sl, 0);
695 		break;
696 	case 400:
697 		__w1_f19_set_i2c_speed(sl, 1);
698 		break;
699 	case 900:
700 		__w1_f19_set_i2c_speed(sl, 2);
701 		break;
702 	default:
703 		/*
704 		 * A i2c_speed module parameter of anything else
705 		 * than 100, 400, 900 means not to touch the
706 		 * speed of the DS28E17.
707 		 * We assume 400kBaud, the power-on value.
708 		 */
709 		data->speed = 1;
710 	}
711 
712 	/*
713 	 * Setup default busy stretch
714 	 * configuration for the DS28E17.
715 	 */
716 	data->stretch = i2c_stretch;
717 
718 	/* Setup I2C adapter. */
719 	data->adapter.owner      = THIS_MODULE;
720 	data->adapter.algo       = &w1_f19_i2c_algorithm;
721 	data->adapter.algo_data  = sl;
722 	strcpy(data->adapter.name, "w1-");
723 	strcat(data->adapter.name, sl->name);
724 	data->adapter.dev.parent = &sl->dev;
725 	data->adapter.quirks     = &w1_f19_i2c_adapter_quirks;
726 
727 	return i2c_add_adapter(&data->adapter);
728 }
729 
w1_f19_remove_slave(struct w1_slave * sl)730 static void w1_f19_remove_slave(struct w1_slave *sl)
731 {
732 	struct w1_f19_data *family_data = sl->family_data;
733 
734 	/* Delete I2C adapter. */
735 	i2c_del_adapter(&family_data->adapter);
736 
737 	/* Free slave specific data. */
738 	devm_kfree(&sl->dev, family_data);
739 	sl->family_data = NULL;
740 }
741 
742 
743 /* Declarations within the w1 subsystem. */
744 static const struct w1_family_ops w1_f19_fops = {
745 	.add_slave = w1_f19_add_slave,
746 	.remove_slave = w1_f19_remove_slave,
747 	.groups = w1_f19_groups,
748 };
749 
750 static struct w1_family w1_family_19 = {
751 	.fid = W1_FAMILY_DS28E17,
752 	.fops = &w1_f19_fops,
753 };
754 
755 module_w1_family(w1_family_19);
756