Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
/*
 * Intersil ISL1208 rtc class driver
 *
 * Copyright 2005,2006 Hebert Valerio Riedel <hvr@gnu.org>
 *
 *  This program is free software; you can redistribute  it and/or modify it
 *  under  the terms of  the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the  License, or (at your
 *  option) any later version.
 *
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>

#define DRV_VERSION "0.3"

/* Register map */
/* rtc section */
#define ISL1208_REG_SC  0x00
#define ISL1208_REG_MN  0x01
#define ISL1208_REG_HR  0x02
#define ISL1208_REG_HR_MIL     (1<<7)	/* 24h/12h mode */
#define ISL1208_REG_HR_PM      (1<<5)	/* PM/AM bit in 12h mode */
#define ISL1208_REG_DT  0x03
#define ISL1208_REG_MO  0x04
#define ISL1208_REG_YR  0x05
#define ISL1208_REG_DW  0x06
#define ISL1208_RTC_SECTION_LEN 7

/* control/status section */
#define ISL1208_REG_SR  0x07
#define ISL1208_REG_SR_ARST    (1<<7)	/* auto reset */
#define ISL1208_REG_SR_XTOSCB  (1<<6)	/* crystal oscillator */
#define ISL1208_REG_SR_WRTC    (1<<4)	/* write rtc */
#define ISL1208_REG_SR_ALM     (1<<2)	/* alarm */
#define ISL1208_REG_SR_BAT     (1<<1)	/* battery */
#define ISL1208_REG_SR_RTCF    (1<<0)	/* rtc fail */
#define ISL1208_REG_INT 0x08
#define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
#define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */
#define ISL1208_REG_09  0x09	/* reserved */
#define ISL1208_REG_ATR 0x0a
#define ISL1208_REG_DTR 0x0b

/* alarm section */
#define ISL1208_REG_SCA 0x0c
#define ISL1208_REG_MNA 0x0d
#define ISL1208_REG_HRA 0x0e
#define ISL1208_REG_DTA 0x0f
#define ISL1208_REG_MOA 0x10
#define ISL1208_REG_DWA 0x11
#define ISL1208_ALARM_SECTION_LEN 6

/* user section */
#define ISL1208_REG_USR1 0x12
#define ISL1208_REG_USR2 0x13
#define ISL1208_USR_SECTION_LEN 2

static struct i2c_driver isl1208_driver;

/* block read */
static int
isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
		      unsigned len)
{
	u8 reg_addr[1] = { reg };
	struct i2c_msg msgs[2] = {
		{client->addr, 0, sizeof(reg_addr), reg_addr}
		,
		{client->addr, I2C_M_RD, len, buf}
	};
	int ret;

	BUG_ON(reg > ISL1208_REG_USR2);
	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);

	ret = i2c_transfer(client->adapter, msgs, 2);
	if (ret > 0)
		ret = 0;
	return ret;
}

/* block write */
static int
isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
		     unsigned len)
{
	u8 i2c_buf[ISL1208_REG_USR2 + 2];
	struct i2c_msg msgs[1] = {
		{client->addr, 0, len + 1, i2c_buf}
	};
	int ret;

	BUG_ON(reg > ISL1208_REG_USR2);
	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);

	i2c_buf[0] = reg;
	memcpy(&i2c_buf[1], &buf[0], len);

	ret = i2c_transfer(client->adapter, msgs, 1);
	if (ret > 0)
		ret = 0;
	return ret;
}

/* simple check to see wether we have a isl1208 */
static int
isl1208_i2c_validate_client(struct i2c_client *client)
{
	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
	};
	int i;
	int ret;

	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
	if (ret < 0)
		return ret;

	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
		if (regs[i] & zero_mask[i])	/* check if bits are cleared */
			return -ENODEV;
	}

	return 0;
}

static int
isl1208_i2c_get_sr(struct i2c_client *client)
{
	int sr = i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
	if (sr < 0)
		return -EIO;

	return sr;
}

static int
isl1208_i2c_get_atr(struct i2c_client *client)
{
	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
	if (atr < 0)
		return atr;

	/* The 6bit value in the ATR register controls the load
	 * capacitance C_load * in steps of 0.25pF
	 *
	 * bit (1<<5) of the ATR register is inverted
	 *
	 * C_load(ATR=0x20) =  4.50pF
	 * C_load(ATR=0x00) = 12.50pF
	 * C_load(ATR=0x1f) = 20.25pF
	 *
	 */

	atr &= 0x3f;		/* mask out lsb */
	atr ^= 1 << 5;		/* invert 6th bit */
	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */

	return atr;
}

static int
isl1208_i2c_get_dtr(struct i2c_client *client)
{
	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
	if (dtr < 0)
		return -EIO;

	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);

	return dtr;
}

static int
isl1208_i2c_get_usr(struct i2c_client *client)
{
	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
	int ret;

	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
				    ISL1208_USR_SECTION_LEN);
	if (ret < 0)
		return ret;

	return (buf[1] << 8) | buf[0];
}

static int
isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
{
	u8 buf[ISL1208_USR_SECTION_LEN];

	buf[0] = usr & 0xff;
	buf[1] = (usr >> 8) & 0xff;

	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
				    ISL1208_USR_SECTION_LEN);
}

static int
isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
{
	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);

	if (icr < 0) {
		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
		return icr;
	}

	if (enable)
		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
	else
		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);

	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
	if (icr < 0) {
		dev_err(&client->dev, "%s: writing INT failed\n", __func__);
		return icr;
	}

	return 0;
}

static int
isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
{
	struct i2c_client *const client = to_i2c_client(dev);
	int sr, dtr, atr, usr;

	sr = isl1208_i2c_get_sr(client);
	if (sr < 0) {
		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
		return sr;
	}

	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);

	seq_printf(seq, "batt_status\t: %s\n",
		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");

	dtr = isl1208_i2c_get_dtr(client);
	if (dtr >= 0 - 1)
		seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);

	atr = isl1208_i2c_get_atr(client);
	if (atr >= 0)
		seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
			   atr >> 2, (atr & 0x3) * 25);

	usr = isl1208_i2c_get_usr(client);
	if (usr >= 0)
		seq_printf(seq, "user_data\t: 0x%.4x\n", usr);

	return 0;
}

static int
isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
{
	int sr;
	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };

	sr = isl1208_i2c_get_sr(client);
	if (sr < 0) {
		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
		return -EIO;
	}

	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
	if (sr < 0) {
		dev_err(&client->dev, "%s: reading RTC section failed\n",
			__func__);
		return sr;
	}

	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);

	/* HR field has a more complex interpretation */
	{
		const u8 _hr = regs[ISL1208_REG_HR];
		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */
			tm->tm_hour = bcd2bin(_hr & 0x3f);
		else {
			/* 12h format */
			tm->tm_hour = bcd2bin(_hr & 0x1f);
			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */
				tm->tm_hour += 12;
		}
	}

	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);

	return 0;
}

static int
isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
{
	struct rtc_time *const tm = &alarm->time;
	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
	int icr, yr, sr = isl1208_i2c_get_sr(client);

	if (sr < 0) {
		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
		return sr;
	}

	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
				   ISL1208_ALARM_SECTION_LEN);
	if (sr < 0) {
		dev_err(&client->dev, "%s: reading alarm section failed\n",
			__func__);
		return sr;
	}

	/* MSB of each alarm register is an enable bit */
	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
	tm->tm_mon =
		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);

	/* The alarm doesn't store the year so get it from the rtc section */
	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
	if (yr < 0) {
		dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
		return yr;
	}
	tm->tm_year = bcd2bin(yr) + 100;

	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
	if (icr < 0) {
		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
		return icr;
	}
	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);

	return 0;
}

static int
isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
{
	struct rtc_time *alarm_tm = &alarm->time;
	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
	const int offs = ISL1208_REG_SCA;
	unsigned long rtc_secs, alarm_secs;
	struct rtc_time rtc_tm;
	int err, enable;

	err = isl1208_i2c_read_time(client, &rtc_tm);
	if (err)
		return err;
	err = rtc_tm_to_time(&rtc_tm, &rtc_secs);
	if (err)
		return err;
	err = rtc_tm_to_time(alarm_tm, &alarm_secs);
	if (err)
		return err;

	/* If the alarm time is before the current time disable the alarm */
	if (!alarm->enabled || alarm_secs <= rtc_secs)
		enable = 0x00;
	else
		enable = 0x80;

	/* Program the alarm and enable it for each setting */
	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
		ISL1208_REG_HR_MIL | enable;

	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;

	/* write ALARM registers */
	err = isl1208_i2c_set_regs(client, offs, regs,
				  ISL1208_ALARM_SECTION_LEN);
	if (err < 0) {
		dev_err(&client->dev, "%s: writing ALARM section failed\n",
			__func__);
		return err;
	}

	err = isl1208_rtc_toggle_alarm(client, enable);
	if (err)
		return err;

	return 0;
}

static int
isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
}

static int
isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
{
	int sr;
	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };

	/* The clock has an 8 bit wide bcd-coded register (they never learn)
	 * for the year. tm_year is an offset from 1900 and we are interested
	 * in the 2000-2099 range, so any value less than 100 is invalid.
	 */
	if (tm->tm_year < 100)
		return -EINVAL;

	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;

	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);

	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);

	sr = isl1208_i2c_get_sr(client);
	if (sr < 0) {
		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
		return sr;
	}

	/* set WRTC */
	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
				       sr | ISL1208_REG_SR_WRTC);
	if (sr < 0) {
		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
		return sr;
	}

	/* write RTC registers */
	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
	if (sr < 0) {
		dev_err(&client->dev, "%s: writing RTC section failed\n",
			__func__);
		return sr;
	}

	/* clear WRTC again */
	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
				       sr & ~ISL1208_REG_SR_WRTC);
	if (sr < 0) {
		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
		return sr;
	}

	return 0;
}


static int
isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
}

static int
isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
}

static int
isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
}

static irqreturn_t
isl1208_rtc_interrupt(int irq, void *data)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
	struct i2c_client *client = data;
	int handled = 0, sr, err;

	/*
	 * I2C reads get NAK'ed if we read straight away after an interrupt?
	 * Using a mdelay/msleep didn't seem to help either, so we work around
	 * this by continually trying to read the register for a short time.
	 */
	while (1) {
		sr = isl1208_i2c_get_sr(client);
		if (sr >= 0)
			break;

		if (time_after(jiffies, timeout)) {
			dev_err(&client->dev, "%s: reading SR failed\n",
				__func__);
			return sr;
		}
	}

	if (sr & ISL1208_REG_SR_ALM) {
		dev_dbg(&client->dev, "alarm!\n");

		/* Clear the alarm */
		sr &= ~ISL1208_REG_SR_ALM;
		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
		if (sr < 0)
			dev_err(&client->dev, "%s: writing SR failed\n",
				__func__);
		else
			handled = 1;

		/* Disable the alarm */
		err = isl1208_rtc_toggle_alarm(client, 0);
		if (err)
			return err;
	}

	return handled ? IRQ_HANDLED : IRQ_NONE;
}

static const struct rtc_class_ops isl1208_rtc_ops = {
	.proc = isl1208_rtc_proc,
	.read_time = isl1208_rtc_read_time,
	.set_time = isl1208_rtc_set_time,
	.read_alarm = isl1208_rtc_read_alarm,
	.set_alarm = isl1208_rtc_set_alarm,
};

/* sysfs interface */

static ssize_t
isl1208_sysfs_show_atrim(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
	if (atr < 0)
		return atr;

	return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
}

static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);

static ssize_t
isl1208_sysfs_show_dtrim(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
	if (dtr < 0)
		return dtr;

	return sprintf(buf, "%d ppm\n", dtr);
}

static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);

static ssize_t
isl1208_sysfs_show_usr(struct device *dev,
		       struct device_attribute *attr, char *buf)
{
	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
	if (usr < 0)
		return usr;

	return sprintf(buf, "0x%.4x\n", usr);
}

static ssize_t
isl1208_sysfs_store_usr(struct device *dev,
			struct device_attribute *attr,
			const char *buf, size_t count)
{
	int usr = -1;

	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
		if (sscanf(buf, "%x", &usr) != 1)
			return -EINVAL;
	} else {
		if (sscanf(buf, "%d", &usr) != 1)
			return -EINVAL;
	}

	if (usr < 0 || usr > 0xffff)
		return -EINVAL;

	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
}

static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
		   isl1208_sysfs_store_usr);

static struct attribute *isl1208_rtc_attrs[] = {
	&dev_attr_atrim.attr,
	&dev_attr_dtrim.attr,
	&dev_attr_usr.attr,
	NULL
};

static const struct attribute_group isl1208_rtc_sysfs_files = {
	.attrs	= isl1208_rtc_attrs,
};

static int
isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
	int rc = 0;
	struct rtc_device *rtc;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -ENODEV;

	if (isl1208_i2c_validate_client(client) < 0)
		return -ENODEV;

	dev_info(&client->dev,
		 "chip found, driver version " DRV_VERSION "\n");

	if (client->irq > 0) {
		rc = request_threaded_irq(client->irq, NULL,
					  isl1208_rtc_interrupt,
					  IRQF_SHARED,
					  isl1208_driver.driver.name, client);
		if (!rc) {
			device_init_wakeup(&client->dev, 1);
			enable_irq_wake(client->irq);
		} else {
			dev_err(&client->dev,
				"Unable to request irq %d, no alarm support\n",
				client->irq);
			client->irq = 0;
		}
	}

	rtc = rtc_device_register(isl1208_driver.driver.name,
				  &client->dev, &isl1208_rtc_ops,
				  THIS_MODULE);
	if (IS_ERR(rtc)) {
		rc = PTR_ERR(rtc);
		goto exit_free_irq;
	}

	i2c_set_clientdata(client, rtc);

	rc = isl1208_i2c_get_sr(client);
	if (rc < 0) {
		dev_err(&client->dev, "reading status failed\n");
		goto exit_unregister;
	}

	if (rc & ISL1208_REG_SR_RTCF)
		dev_warn(&client->dev, "rtc power failure detected, "
			 "please set clock.\n");

	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
	if (rc)
		goto exit_unregister;

	return 0;

exit_unregister:
	rtc_device_unregister(rtc);
exit_free_irq:
	if (client->irq)
		free_irq(client->irq, client);

	return rc;
}

static int
isl1208_remove(struct i2c_client *client)
{
	struct rtc_device *rtc = i2c_get_clientdata(client);

	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
	rtc_device_unregister(rtc);
	if (client->irq)
		free_irq(client->irq, client);

	return 0;
}

static const struct i2c_device_id isl1208_id[] = {
	{ "isl1208", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, isl1208_id);

static struct i2c_driver isl1208_driver = {
	.driver = {
		   .name = "rtc-isl1208",
		   },
	.probe = isl1208_probe,
	.remove = isl1208_remove,
	.id_table = isl1208_id,
};

static int __init
isl1208_init(void)
{
	return i2c_add_driver(&isl1208_driver);
}

static void __exit
isl1208_exit(void)
{
	i2c_del_driver(&isl1208_driver);
}

MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(isl1208_init);
module_exit(isl1208_exit);