xref: /linux/drivers/rtc/rtc-isl1208.c (revision 93d90ad708b8da6efc0e487b66111aa9db7f70c7)
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 		{
72 			.addr = client->addr,
73 			.len = sizeof(reg_addr),
74 			.buf = reg_addr
75 		},
76 		{
77 			.addr = client->addr,
78 			.flags = I2C_M_RD,
79 			.len = len,
80 			.buf = buf
81 		}
82 	};
83 	int ret;
84 
85 	BUG_ON(reg > ISL1208_REG_USR2);
86 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
87 
88 	ret = i2c_transfer(client->adapter, msgs, 2);
89 	if (ret > 0)
90 		ret = 0;
91 	return ret;
92 }
93 
94 /* block write */
95 static int
96 isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
97 		     unsigned len)
98 {
99 	u8 i2c_buf[ISL1208_REG_USR2 + 2];
100 	struct i2c_msg msgs[1] = {
101 		{
102 			.addr = client->addr,
103 			.len = len + 1,
104 			.buf = i2c_buf
105 		}
106 	};
107 	int ret;
108 
109 	BUG_ON(reg > ISL1208_REG_USR2);
110 	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
111 
112 	i2c_buf[0] = reg;
113 	memcpy(&i2c_buf[1], &buf[0], len);
114 
115 	ret = i2c_transfer(client->adapter, msgs, 1);
116 	if (ret > 0)
117 		ret = 0;
118 	return ret;
119 }
120 
121 /* simple check to see whether we have a isl1208 */
122 static int
123 isl1208_i2c_validate_client(struct i2c_client *client)
124 {
125 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
126 	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
127 		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
128 	};
129 	int i;
130 	int ret;
131 
132 	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
133 	if (ret < 0)
134 		return ret;
135 
136 	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
137 		if (regs[i] & zero_mask[i])	/* check if bits are cleared */
138 			return -ENODEV;
139 	}
140 
141 	return 0;
142 }
143 
144 static int
145 isl1208_i2c_get_sr(struct i2c_client *client)
146 {
147 	return i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
148 }
149 
150 static int
151 isl1208_i2c_get_atr(struct i2c_client *client)
152 {
153 	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
154 	if (atr < 0)
155 		return atr;
156 
157 	/* The 6bit value in the ATR register controls the load
158 	 * capacitance C_load * in steps of 0.25pF
159 	 *
160 	 * bit (1<<5) of the ATR register is inverted
161 	 *
162 	 * C_load(ATR=0x20) =  4.50pF
163 	 * C_load(ATR=0x00) = 12.50pF
164 	 * C_load(ATR=0x1f) = 20.25pF
165 	 *
166 	 */
167 
168 	atr &= 0x3f;		/* mask out lsb */
169 	atr ^= 1 << 5;		/* invert 6th bit */
170 	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */
171 
172 	return atr;
173 }
174 
175 static int
176 isl1208_i2c_get_dtr(struct i2c_client *client)
177 {
178 	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
179 	if (dtr < 0)
180 		return -EIO;
181 
182 	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
183 	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);
184 
185 	return dtr;
186 }
187 
188 static int
189 isl1208_i2c_get_usr(struct i2c_client *client)
190 {
191 	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
192 	int ret;
193 
194 	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
195 				    ISL1208_USR_SECTION_LEN);
196 	if (ret < 0)
197 		return ret;
198 
199 	return (buf[1] << 8) | buf[0];
200 }
201 
202 static int
203 isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
204 {
205 	u8 buf[ISL1208_USR_SECTION_LEN];
206 
207 	buf[0] = usr & 0xff;
208 	buf[1] = (usr >> 8) & 0xff;
209 
210 	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
211 				    ISL1208_USR_SECTION_LEN);
212 }
213 
214 static int
215 isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
216 {
217 	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
218 
219 	if (icr < 0) {
220 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
221 		return icr;
222 	}
223 
224 	if (enable)
225 		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
226 	else
227 		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
228 
229 	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
230 	if (icr < 0) {
231 		dev_err(&client->dev, "%s: writing INT failed\n", __func__);
232 		return icr;
233 	}
234 
235 	return 0;
236 }
237 
238 static int
239 isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
240 {
241 	struct i2c_client *const client = to_i2c_client(dev);
242 	int sr, dtr, atr, usr;
243 
244 	sr = isl1208_i2c_get_sr(client);
245 	if (sr < 0) {
246 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
247 		return sr;
248 	}
249 
250 	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
251 		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
252 		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
253 		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
254 		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
255 		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
256 		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);
257 
258 	seq_printf(seq, "batt_status\t: %s\n",
259 		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
260 
261 	dtr = isl1208_i2c_get_dtr(client);
262 	if (dtr >= 0 - 1)
263 		seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);
264 
265 	atr = isl1208_i2c_get_atr(client);
266 	if (atr >= 0)
267 		seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
268 			   atr >> 2, (atr & 0x3) * 25);
269 
270 	usr = isl1208_i2c_get_usr(client);
271 	if (usr >= 0)
272 		seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
273 
274 	return 0;
275 }
276 
277 static int
278 isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
279 {
280 	int sr;
281 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
282 
283 	sr = isl1208_i2c_get_sr(client);
284 	if (sr < 0) {
285 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
286 		return -EIO;
287 	}
288 
289 	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
290 	if (sr < 0) {
291 		dev_err(&client->dev, "%s: reading RTC section failed\n",
292 			__func__);
293 		return sr;
294 	}
295 
296 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
297 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);
298 
299 	/* HR field has a more complex interpretation */
300 	{
301 		const u8 _hr = regs[ISL1208_REG_HR];
302 		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */
303 			tm->tm_hour = bcd2bin(_hr & 0x3f);
304 		else {
305 			/* 12h format */
306 			tm->tm_hour = bcd2bin(_hr & 0x1f);
307 			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */
308 				tm->tm_hour += 12;
309 		}
310 	}
311 
312 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
313 	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
314 	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
315 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);
316 
317 	return 0;
318 }
319 
320 static int
321 isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
322 {
323 	struct rtc_time *const tm = &alarm->time;
324 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
325 	int icr, yr, sr = isl1208_i2c_get_sr(client);
326 
327 	if (sr < 0) {
328 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
329 		return sr;
330 	}
331 
332 	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
333 				   ISL1208_ALARM_SECTION_LEN);
334 	if (sr < 0) {
335 		dev_err(&client->dev, "%s: reading alarm section failed\n",
336 			__func__);
337 		return sr;
338 	}
339 
340 	/* MSB of each alarm register is an enable bit */
341 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
342 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
343 	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
344 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
345 	tm->tm_mon =
346 		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
347 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);
348 
349 	/* The alarm doesn't store the year so get it from the rtc section */
350 	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
351 	if (yr < 0) {
352 		dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
353 		return yr;
354 	}
355 	tm->tm_year = bcd2bin(yr) + 100;
356 
357 	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
358 	if (icr < 0) {
359 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
360 		return icr;
361 	}
362 	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
363 
364 	return 0;
365 }
366 
367 static int
368 isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
369 {
370 	struct rtc_time *alarm_tm = &alarm->time;
371 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
372 	const int offs = ISL1208_REG_SCA;
373 	unsigned long rtc_secs, alarm_secs;
374 	struct rtc_time rtc_tm;
375 	int err, enable;
376 
377 	err = isl1208_i2c_read_time(client, &rtc_tm);
378 	if (err)
379 		return err;
380 	err = rtc_tm_to_time(&rtc_tm, &rtc_secs);
381 	if (err)
382 		return err;
383 	err = rtc_tm_to_time(alarm_tm, &alarm_secs);
384 	if (err)
385 		return err;
386 
387 	/* If the alarm time is before the current time disable the alarm */
388 	if (!alarm->enabled || alarm_secs <= rtc_secs)
389 		enable = 0x00;
390 	else
391 		enable = 0x80;
392 
393 	/* Program the alarm and enable it for each setting */
394 	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
395 	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
396 	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
397 		ISL1208_REG_HR_MIL | enable;
398 
399 	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
400 	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
401 	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
402 
403 	/* write ALARM registers */
404 	err = isl1208_i2c_set_regs(client, offs, regs,
405 				  ISL1208_ALARM_SECTION_LEN);
406 	if (err < 0) {
407 		dev_err(&client->dev, "%s: writing ALARM section failed\n",
408 			__func__);
409 		return err;
410 	}
411 
412 	err = isl1208_rtc_toggle_alarm(client, enable);
413 	if (err)
414 		return err;
415 
416 	return 0;
417 }
418 
419 static int
420 isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
421 {
422 	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
423 }
424 
425 static int
426 isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
427 {
428 	int sr;
429 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
430 
431 	/* The clock has an 8 bit wide bcd-coded register (they never learn)
432 	 * for the year. tm_year is an offset from 1900 and we are interested
433 	 * in the 2000-2099 range, so any value less than 100 is invalid.
434 	 */
435 	if (tm->tm_year < 100)
436 		return -EINVAL;
437 
438 	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
439 	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
440 	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;
441 
442 	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
443 	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
444 	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);
445 
446 	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);
447 
448 	sr = isl1208_i2c_get_sr(client);
449 	if (sr < 0) {
450 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
451 		return sr;
452 	}
453 
454 	/* set WRTC */
455 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
456 				       sr | ISL1208_REG_SR_WRTC);
457 	if (sr < 0) {
458 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
459 		return sr;
460 	}
461 
462 	/* write RTC registers */
463 	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
464 	if (sr < 0) {
465 		dev_err(&client->dev, "%s: writing RTC section failed\n",
466 			__func__);
467 		return sr;
468 	}
469 
470 	/* clear WRTC again */
471 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
472 				       sr & ~ISL1208_REG_SR_WRTC);
473 	if (sr < 0) {
474 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
475 		return sr;
476 	}
477 
478 	return 0;
479 }
480 
481 
482 static int
483 isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
484 {
485 	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
486 }
487 
488 static int
489 isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
490 {
491 	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
492 }
493 
494 static int
495 isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
496 {
497 	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
498 }
499 
500 static irqreturn_t
501 isl1208_rtc_interrupt(int irq, void *data)
502 {
503 	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
504 	struct i2c_client *client = data;
505 	struct rtc_device *rtc = i2c_get_clientdata(client);
506 	int handled = 0, sr, err;
507 
508 	/*
509 	 * I2C reads get NAK'ed if we read straight away after an interrupt?
510 	 * Using a mdelay/msleep didn't seem to help either, so we work around
511 	 * this by continually trying to read the register for a short time.
512 	 */
513 	while (1) {
514 		sr = isl1208_i2c_get_sr(client);
515 		if (sr >= 0)
516 			break;
517 
518 		if (time_after(jiffies, timeout)) {
519 			dev_err(&client->dev, "%s: reading SR failed\n",
520 				__func__);
521 			return sr;
522 		}
523 	}
524 
525 	if (sr & ISL1208_REG_SR_ALM) {
526 		dev_dbg(&client->dev, "alarm!\n");
527 
528 		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
529 
530 		/* Clear the alarm */
531 		sr &= ~ISL1208_REG_SR_ALM;
532 		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
533 		if (sr < 0)
534 			dev_err(&client->dev, "%s: writing SR failed\n",
535 				__func__);
536 		else
537 			handled = 1;
538 
539 		/* Disable the alarm */
540 		err = isl1208_rtc_toggle_alarm(client, 0);
541 		if (err)
542 			return err;
543 	}
544 
545 	return handled ? IRQ_HANDLED : IRQ_NONE;
546 }
547 
548 static const struct rtc_class_ops isl1208_rtc_ops = {
549 	.proc = isl1208_rtc_proc,
550 	.read_time = isl1208_rtc_read_time,
551 	.set_time = isl1208_rtc_set_time,
552 	.read_alarm = isl1208_rtc_read_alarm,
553 	.set_alarm = isl1208_rtc_set_alarm,
554 };
555 
556 /* sysfs interface */
557 
558 static ssize_t
559 isl1208_sysfs_show_atrim(struct device *dev,
560 			 struct device_attribute *attr, char *buf)
561 {
562 	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
563 	if (atr < 0)
564 		return atr;
565 
566 	return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
567 }
568 
569 static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);
570 
571 static ssize_t
572 isl1208_sysfs_show_dtrim(struct device *dev,
573 			 struct device_attribute *attr, char *buf)
574 {
575 	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
576 	if (dtr < 0)
577 		return dtr;
578 
579 	return sprintf(buf, "%d ppm\n", dtr);
580 }
581 
582 static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);
583 
584 static ssize_t
585 isl1208_sysfs_show_usr(struct device *dev,
586 		       struct device_attribute *attr, char *buf)
587 {
588 	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
589 	if (usr < 0)
590 		return usr;
591 
592 	return sprintf(buf, "0x%.4x\n", usr);
593 }
594 
595 static ssize_t
596 isl1208_sysfs_store_usr(struct device *dev,
597 			struct device_attribute *attr,
598 			const char *buf, size_t count)
599 {
600 	int usr = -1;
601 
602 	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
603 		if (sscanf(buf, "%x", &usr) != 1)
604 			return -EINVAL;
605 	} else {
606 		if (sscanf(buf, "%d", &usr) != 1)
607 			return -EINVAL;
608 	}
609 
610 	if (usr < 0 || usr > 0xffff)
611 		return -EINVAL;
612 
613 	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
614 }
615 
616 static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
617 		   isl1208_sysfs_store_usr);
618 
619 static struct attribute *isl1208_rtc_attrs[] = {
620 	&dev_attr_atrim.attr,
621 	&dev_attr_dtrim.attr,
622 	&dev_attr_usr.attr,
623 	NULL
624 };
625 
626 static const struct attribute_group isl1208_rtc_sysfs_files = {
627 	.attrs	= isl1208_rtc_attrs,
628 };
629 
630 static int
631 isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
632 {
633 	int rc = 0;
634 	struct rtc_device *rtc;
635 
636 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
637 		return -ENODEV;
638 
639 	if (isl1208_i2c_validate_client(client) < 0)
640 		return -ENODEV;
641 
642 	dev_info(&client->dev,
643 		 "chip found, driver version " DRV_VERSION "\n");
644 
645 	if (client->irq > 0) {
646 		rc = devm_request_threaded_irq(&client->dev, client->irq, NULL,
647 					       isl1208_rtc_interrupt,
648 					       IRQF_SHARED,
649 					       isl1208_driver.driver.name,
650 					       client);
651 		if (!rc) {
652 			device_init_wakeup(&client->dev, 1);
653 			enable_irq_wake(client->irq);
654 		} else {
655 			dev_err(&client->dev,
656 				"Unable to request irq %d, no alarm support\n",
657 				client->irq);
658 			client->irq = 0;
659 		}
660 	}
661 
662 	rtc = devm_rtc_device_register(&client->dev, isl1208_driver.driver.name,
663 				  &isl1208_rtc_ops,
664 				  THIS_MODULE);
665 	if (IS_ERR(rtc))
666 		return PTR_ERR(rtc);
667 
668 	i2c_set_clientdata(client, rtc);
669 
670 	rc = isl1208_i2c_get_sr(client);
671 	if (rc < 0) {
672 		dev_err(&client->dev, "reading status failed\n");
673 		return rc;
674 	}
675 
676 	if (rc & ISL1208_REG_SR_RTCF)
677 		dev_warn(&client->dev, "rtc power failure detected, "
678 			 "please set clock.\n");
679 
680 	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
681 	if (rc)
682 		return rc;
683 
684 	return 0;
685 }
686 
687 static int
688 isl1208_remove(struct i2c_client *client)
689 {
690 	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
691 
692 	return 0;
693 }
694 
695 static const struct i2c_device_id isl1208_id[] = {
696 	{ "isl1208", 0 },
697 	{ "isl1218", 0 },
698 	{ }
699 };
700 MODULE_DEVICE_TABLE(i2c, isl1208_id);
701 
702 static struct i2c_driver isl1208_driver = {
703 	.driver = {
704 		   .name = "rtc-isl1208",
705 		   },
706 	.probe = isl1208_probe,
707 	.remove = isl1208_remove,
708 	.id_table = isl1208_id,
709 };
710 
711 module_i2c_driver(isl1208_driver);
712 
713 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
714 MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
715 MODULE_LICENSE("GPL");
716 MODULE_VERSION(DRV_VERSION);
717