xref: /openbmc/linux/drivers/rtc/rtc-isl1208.c (revision 9cdb81c7)
1 /*
2  * Intersil ISL1208 rtc class driver
3  *
4  * Copyright 2005,2006 Hebert Valerio Riedel <hvr@gnu.org>
5  *
6  *  This program is free software; you can redistribute  it and/or modify it
7  *  under  the terms of  the GNU General  Public License as published by the
8  *  Free Software Foundation;  either version 2 of the  License, or (at your
9  *  option) any later version.
10  *
11  */
12 
13 #include <linux/module.h>
14 #include <linux/i2c.h>
15 #include <linux/bcd.h>
16 #include <linux/rtc.h>
17 
18 #define DRV_VERSION "0.3"
19 
20 /* Register map */
21 /* rtc section */
22 #define ISL1208_REG_SC  0x00
23 #define ISL1208_REG_MN  0x01
24 #define ISL1208_REG_HR  0x02
25 #define ISL1208_REG_HR_MIL     (1<<7)	/* 24h/12h mode */
26 #define ISL1208_REG_HR_PM      (1<<5)	/* PM/AM bit in 12h mode */
27 #define ISL1208_REG_DT  0x03
28 #define ISL1208_REG_MO  0x04
29 #define ISL1208_REG_YR  0x05
30 #define ISL1208_REG_DW  0x06
31 #define ISL1208_RTC_SECTION_LEN 7
32 
33 /* control/status section */
34 #define ISL1208_REG_SR  0x07
35 #define ISL1208_REG_SR_ARST    (1<<7)	/* auto reset */
36 #define ISL1208_REG_SR_XTOSCB  (1<<6)	/* crystal oscillator */
37 #define ISL1208_REG_SR_WRTC    (1<<4)	/* write rtc */
38 #define ISL1208_REG_SR_ALM     (1<<2)	/* alarm */
39 #define ISL1208_REG_SR_BAT     (1<<1)	/* battery */
40 #define ISL1208_REG_SR_RTCF    (1<<0)	/* rtc fail */
41 #define ISL1208_REG_INT 0x08
42 #define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
43 #define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */
44 #define ISL1208_REG_09  0x09	/* reserved */
45 #define ISL1208_REG_ATR 0x0a
46 #define ISL1208_REG_DTR 0x0b
47 
48 /* alarm section */
49 #define ISL1208_REG_SCA 0x0c
50 #define ISL1208_REG_MNA 0x0d
51 #define ISL1208_REG_HRA 0x0e
52 #define ISL1208_REG_DTA 0x0f
53 #define ISL1208_REG_MOA 0x10
54 #define ISL1208_REG_DWA 0x11
55 #define ISL1208_ALARM_SECTION_LEN 6
56 
57 /* user section */
58 #define ISL1208_REG_USR1 0x12
59 #define ISL1208_REG_USR2 0x13
60 #define ISL1208_USR_SECTION_LEN 2
61 
62 static struct i2c_driver isl1208_driver;
63 
64 /* block read */
65 static int
66 isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
67 		      unsigned len)
68 {
69 	u8 reg_addr[1] = { reg };
70 	struct i2c_msg msgs[2] = {
71 		{client->addr, 0, sizeof(reg_addr), reg_addr}
72 		,
73 		{client->addr, I2C_M_RD, len, buf}
74 	};
75 	int ret;
76 
77 	BUG_ON(reg > ISL1208_REG_USR2);
78 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
79 
80 	ret = i2c_transfer(client->adapter, msgs, 2);
81 	if (ret > 0)
82 		ret = 0;
83 	return ret;
84 }
85 
86 /* block write */
87 static int
88 isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
89 		     unsigned len)
90 {
91 	u8 i2c_buf[ISL1208_REG_USR2 + 2];
92 	struct i2c_msg msgs[1] = {
93 		{client->addr, 0, len + 1, i2c_buf}
94 	};
95 	int ret;
96 
97 	BUG_ON(reg > ISL1208_REG_USR2);
98 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
99 
100 	i2c_buf[0] = reg;
101 	memcpy(&i2c_buf[1], &buf[0], len);
102 
103 	ret = i2c_transfer(client->adapter, msgs, 1);
104 	if (ret > 0)
105 		ret = 0;
106 	return ret;
107 }
108 
109 /* simple check to see wether we have a isl1208 */
110 static int
111 isl1208_i2c_validate_client(struct i2c_client *client)
112 {
113 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
114 	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
115 		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
116 	};
117 	int i;
118 	int ret;
119 
120 	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
121 	if (ret < 0)
122 		return ret;
123 
124 	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
125 		if (regs[i] & zero_mask[i])	/* check if bits are cleared */
126 			return -ENODEV;
127 	}
128 
129 	return 0;
130 }
131 
132 static int
133 isl1208_i2c_get_sr(struct i2c_client *client)
134 {
135 	int sr = i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
136 	if (sr < 0)
137 		return -EIO;
138 
139 	return sr;
140 }
141 
142 static int
143 isl1208_i2c_get_atr(struct i2c_client *client)
144 {
145 	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
146 	if (atr < 0)
147 		return atr;
148 
149 	/* The 6bit value in the ATR register controls the load
150 	 * capacitance C_load * in steps of 0.25pF
151 	 *
152 	 * bit (1<<5) of the ATR register is inverted
153 	 *
154 	 * C_load(ATR=0x20) =  4.50pF
155 	 * C_load(ATR=0x00) = 12.50pF
156 	 * C_load(ATR=0x1f) = 20.25pF
157 	 *
158 	 */
159 
160 	atr &= 0x3f;		/* mask out lsb */
161 	atr ^= 1 << 5;		/* invert 6th bit */
162 	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */
163 
164 	return atr;
165 }
166 
167 static int
168 isl1208_i2c_get_dtr(struct i2c_client *client)
169 {
170 	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
171 	if (dtr < 0)
172 		return -EIO;
173 
174 	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
175 	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);
176 
177 	return dtr;
178 }
179 
180 static int
181 isl1208_i2c_get_usr(struct i2c_client *client)
182 {
183 	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
184 	int ret;
185 
186 	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
187 				    ISL1208_USR_SECTION_LEN);
188 	if (ret < 0)
189 		return ret;
190 
191 	return (buf[1] << 8) | buf[0];
192 }
193 
194 static int
195 isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
196 {
197 	u8 buf[ISL1208_USR_SECTION_LEN];
198 
199 	buf[0] = usr & 0xff;
200 	buf[1] = (usr >> 8) & 0xff;
201 
202 	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
203 				    ISL1208_USR_SECTION_LEN);
204 }
205 
206 static int
207 isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
208 {
209 	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
210 
211 	if (icr < 0) {
212 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
213 		return icr;
214 	}
215 
216 	if (enable)
217 		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
218 	else
219 		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
220 
221 	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
222 	if (icr < 0) {
223 		dev_err(&client->dev, "%s: writing INT failed\n", __func__);
224 		return icr;
225 	}
226 
227 	return 0;
228 }
229 
230 static int
231 isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
232 {
233 	struct i2c_client *const client = to_i2c_client(dev);
234 	int sr, dtr, atr, usr;
235 
236 	sr = isl1208_i2c_get_sr(client);
237 	if (sr < 0) {
238 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
239 		return sr;
240 	}
241 
242 	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
243 		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
244 		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
245 		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
246 		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
247 		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
248 		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);
249 
250 	seq_printf(seq, "batt_status\t: %s\n",
251 		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
252 
253 	dtr = isl1208_i2c_get_dtr(client);
254 	if (dtr >= 0 - 1)
255 		seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);
256 
257 	atr = isl1208_i2c_get_atr(client);
258 	if (atr >= 0)
259 		seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
260 			   atr >> 2, (atr & 0x3) * 25);
261 
262 	usr = isl1208_i2c_get_usr(client);
263 	if (usr >= 0)
264 		seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
265 
266 	return 0;
267 }
268 
269 static int
270 isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
271 {
272 	int sr;
273 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
274 
275 	sr = isl1208_i2c_get_sr(client);
276 	if (sr < 0) {
277 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
278 		return -EIO;
279 	}
280 
281 	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
282 	if (sr < 0) {
283 		dev_err(&client->dev, "%s: reading RTC section failed\n",
284 			__func__);
285 		return sr;
286 	}
287 
288 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
289 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);
290 
291 	/* HR field has a more complex interpretation */
292 	{
293 		const u8 _hr = regs[ISL1208_REG_HR];
294 		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */
295 			tm->tm_hour = bcd2bin(_hr & 0x3f);
296 		else {
297 			/* 12h format */
298 			tm->tm_hour = bcd2bin(_hr & 0x1f);
299 			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */
300 				tm->tm_hour += 12;
301 		}
302 	}
303 
304 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
305 	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
306 	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
307 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);
308 
309 	return 0;
310 }
311 
312 static int
313 isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
314 {
315 	struct rtc_time *const tm = &alarm->time;
316 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
317 	int icr, yr, sr = isl1208_i2c_get_sr(client);
318 
319 	if (sr < 0) {
320 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
321 		return sr;
322 	}
323 
324 	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
325 				   ISL1208_ALARM_SECTION_LEN);
326 	if (sr < 0) {
327 		dev_err(&client->dev, "%s: reading alarm section failed\n",
328 			__func__);
329 		return sr;
330 	}
331 
332 	/* MSB of each alarm register is an enable bit */
333 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
334 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
335 	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
336 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
337 	tm->tm_mon =
338 		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
339 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);
340 
341 	/* The alarm doesn't store the year so get it from the rtc section */
342 	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
343 	if (yr < 0) {
344 		dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
345 		return yr;
346 	}
347 	tm->tm_year = bcd2bin(yr) + 100;
348 
349 	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
350 	if (icr < 0) {
351 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
352 		return icr;
353 	}
354 	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
355 
356 	return 0;
357 }
358 
359 static int
360 isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
361 {
362 	struct rtc_time *alarm_tm = &alarm->time;
363 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
364 	const int offs = ISL1208_REG_SCA;
365 	unsigned long rtc_secs, alarm_secs;
366 	struct rtc_time rtc_tm;
367 	int err, enable;
368 
369 	err = isl1208_i2c_read_time(client, &rtc_tm);
370 	if (err)
371 		return err;
372 	err = rtc_tm_to_time(&rtc_tm, &rtc_secs);
373 	if (err)
374 		return err;
375 	err = rtc_tm_to_time(alarm_tm, &alarm_secs);
376 	if (err)
377 		return err;
378 
379 	/* If the alarm time is before the current time disable the alarm */
380 	if (!alarm->enabled || alarm_secs <= rtc_secs)
381 		enable = 0x00;
382 	else
383 		enable = 0x80;
384 
385 	/* Program the alarm and enable it for each setting */
386 	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
387 	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
388 	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
389 		ISL1208_REG_HR_MIL | enable;
390 
391 	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
392 	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
393 	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
394 
395 	/* write ALARM registers */
396 	err = isl1208_i2c_set_regs(client, offs, regs,
397 				  ISL1208_ALARM_SECTION_LEN);
398 	if (err < 0) {
399 		dev_err(&client->dev, "%s: writing ALARM section failed\n",
400 			__func__);
401 		return err;
402 	}
403 
404 	err = isl1208_rtc_toggle_alarm(client, enable);
405 	if (err)
406 		return err;
407 
408 	return 0;
409 }
410 
411 static int
412 isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
413 {
414 	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
415 }
416 
417 static int
418 isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
419 {
420 	int sr;
421 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
422 
423 	/* The clock has an 8 bit wide bcd-coded register (they never learn)
424 	 * for the year. tm_year is an offset from 1900 and we are interested
425 	 * in the 2000-2099 range, so any value less than 100 is invalid.
426 	 */
427 	if (tm->tm_year < 100)
428 		return -EINVAL;
429 
430 	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
431 	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
432 	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;
433 
434 	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
435 	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
436 	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);
437 
438 	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);
439 
440 	sr = isl1208_i2c_get_sr(client);
441 	if (sr < 0) {
442 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
443 		return sr;
444 	}
445 
446 	/* set WRTC */
447 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
448 				       sr | ISL1208_REG_SR_WRTC);
449 	if (sr < 0) {
450 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
451 		return sr;
452 	}
453 
454 	/* write RTC registers */
455 	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
456 	if (sr < 0) {
457 		dev_err(&client->dev, "%s: writing RTC section failed\n",
458 			__func__);
459 		return sr;
460 	}
461 
462 	/* clear WRTC again */
463 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
464 				       sr & ~ISL1208_REG_SR_WRTC);
465 	if (sr < 0) {
466 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
467 		return sr;
468 	}
469 
470 	return 0;
471 }
472 
473 
474 static int
475 isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
476 {
477 	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
478 }
479 
480 static int
481 isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
482 {
483 	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
484 }
485 
486 static int
487 isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
488 {
489 	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
490 }
491 
492 static irqreturn_t
493 isl1208_rtc_interrupt(int irq, void *data)
494 {
495 	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
496 	struct i2c_client *client = data;
497 	int handled = 0, sr, err;
498 
499 	/*
500 	 * I2C reads get NAK'ed if we read straight away after an interrupt?
501 	 * Using a mdelay/msleep didn't seem to help either, so we work around
502 	 * this by continually trying to read the register for a short time.
503 	 */
504 	while (1) {
505 		sr = isl1208_i2c_get_sr(client);
506 		if (sr >= 0)
507 			break;
508 
509 		if (time_after(jiffies, timeout)) {
510 			dev_err(&client->dev, "%s: reading SR failed\n",
511 				__func__);
512 			return sr;
513 		}
514 	}
515 
516 	if (sr & ISL1208_REG_SR_ALM) {
517 		dev_dbg(&client->dev, "alarm!\n");
518 
519 		/* Clear the alarm */
520 		sr &= ~ISL1208_REG_SR_ALM;
521 		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
522 		if (sr < 0)
523 			dev_err(&client->dev, "%s: writing SR failed\n",
524 				__func__);
525 		else
526 			handled = 1;
527 
528 		/* Disable the alarm */
529 		err = isl1208_rtc_toggle_alarm(client, 0);
530 		if (err)
531 			return err;
532 	}
533 
534 	return handled ? IRQ_HANDLED : IRQ_NONE;
535 }
536 
537 static const struct rtc_class_ops isl1208_rtc_ops = {
538 	.proc = isl1208_rtc_proc,
539 	.read_time = isl1208_rtc_read_time,
540 	.set_time = isl1208_rtc_set_time,
541 	.read_alarm = isl1208_rtc_read_alarm,
542 	.set_alarm = isl1208_rtc_set_alarm,
543 };
544 
545 /* sysfs interface */
546 
547 static ssize_t
548 isl1208_sysfs_show_atrim(struct device *dev,
549 			 struct device_attribute *attr, char *buf)
550 {
551 	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
552 	if (atr < 0)
553 		return atr;
554 
555 	return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
556 }
557 
558 static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);
559 
560 static ssize_t
561 isl1208_sysfs_show_dtrim(struct device *dev,
562 			 struct device_attribute *attr, char *buf)
563 {
564 	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
565 	if (dtr < 0)
566 		return dtr;
567 
568 	return sprintf(buf, "%d ppm\n", dtr);
569 }
570 
571 static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);
572 
573 static ssize_t
574 isl1208_sysfs_show_usr(struct device *dev,
575 		       struct device_attribute *attr, char *buf)
576 {
577 	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
578 	if (usr < 0)
579 		return usr;
580 
581 	return sprintf(buf, "0x%.4x\n", usr);
582 }
583 
584 static ssize_t
585 isl1208_sysfs_store_usr(struct device *dev,
586 			struct device_attribute *attr,
587 			const char *buf, size_t count)
588 {
589 	int usr = -1;
590 
591 	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
592 		if (sscanf(buf, "%x", &usr) != 1)
593 			return -EINVAL;
594 	} else {
595 		if (sscanf(buf, "%d", &usr) != 1)
596 			return -EINVAL;
597 	}
598 
599 	if (usr < 0 || usr > 0xffff)
600 		return -EINVAL;
601 
602 	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
603 }
604 
605 static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
606 		   isl1208_sysfs_store_usr);
607 
608 static struct attribute *isl1208_rtc_attrs[] = {
609 	&dev_attr_atrim.attr,
610 	&dev_attr_dtrim.attr,
611 	&dev_attr_usr.attr,
612 	NULL
613 };
614 
615 static const struct attribute_group isl1208_rtc_sysfs_files = {
616 	.attrs	= isl1208_rtc_attrs,
617 };
618 
619 static int
620 isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
621 {
622 	int rc = 0;
623 	struct rtc_device *rtc;
624 
625 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
626 		return -ENODEV;
627 
628 	if (isl1208_i2c_validate_client(client) < 0)
629 		return -ENODEV;
630 
631 	dev_info(&client->dev,
632 		 "chip found, driver version " DRV_VERSION "\n");
633 
634 	if (client->irq > 0) {
635 		rc = request_threaded_irq(client->irq, NULL,
636 					  isl1208_rtc_interrupt,
637 					  IRQF_SHARED,
638 					  isl1208_driver.driver.name, client);
639 		if (!rc) {
640 			device_init_wakeup(&client->dev, 1);
641 			enable_irq_wake(client->irq);
642 		} else {
643 			dev_err(&client->dev,
644 				"Unable to request irq %d, no alarm support\n",
645 				client->irq);
646 			client->irq = 0;
647 		}
648 	}
649 
650 	rtc = rtc_device_register(isl1208_driver.driver.name,
651 				  &client->dev, &isl1208_rtc_ops,
652 				  THIS_MODULE);
653 	if (IS_ERR(rtc)) {
654 		rc = PTR_ERR(rtc);
655 		goto exit_free_irq;
656 	}
657 
658 	i2c_set_clientdata(client, rtc);
659 
660 	rc = isl1208_i2c_get_sr(client);
661 	if (rc < 0) {
662 		dev_err(&client->dev, "reading status failed\n");
663 		goto exit_unregister;
664 	}
665 
666 	if (rc & ISL1208_REG_SR_RTCF)
667 		dev_warn(&client->dev, "rtc power failure detected, "
668 			 "please set clock.\n");
669 
670 	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
671 	if (rc)
672 		goto exit_unregister;
673 
674 	return 0;
675 
676 exit_unregister:
677 	rtc_device_unregister(rtc);
678 exit_free_irq:
679 	if (client->irq)
680 		free_irq(client->irq, client);
681 
682 	return rc;
683 }
684 
685 static int
686 isl1208_remove(struct i2c_client *client)
687 {
688 	struct rtc_device *rtc = i2c_get_clientdata(client);
689 
690 	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
691 	rtc_device_unregister(rtc);
692 	if (client->irq)
693 		free_irq(client->irq, client);
694 
695 	return 0;
696 }
697 
698 static const struct i2c_device_id isl1208_id[] = {
699 	{ "isl1208", 0 },
700 	{ }
701 };
702 MODULE_DEVICE_TABLE(i2c, isl1208_id);
703 
704 static struct i2c_driver isl1208_driver = {
705 	.driver = {
706 		   .name = "rtc-isl1208",
707 		   },
708 	.probe = isl1208_probe,
709 	.remove = isl1208_remove,
710 	.id_table = isl1208_id,
711 };
712 
713 module_i2c_driver(isl1208_driver);
714 
715 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
716 MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
717 MODULE_LICENSE("GPL");
718 MODULE_VERSION(DRV_VERSION);
719