xref: /linux/drivers/rtc/rtc-isl1208.c (revision e9f0878c4b2004ac19581274c1ae4c61ae3ca70e)
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 #include "rtc-core.h"
18 #include <linux/of_irq.h>
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_EVT     (1<<3)	/* event */
39 #define ISL1208_REG_SR_ALM     (1<<2)	/* alarm */
40 #define ISL1208_REG_SR_BAT     (1<<1)	/* battery */
41 #define ISL1208_REG_SR_RTCF    (1<<0)	/* rtc fail */
42 #define ISL1208_REG_INT 0x08
43 #define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
44 #define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */
45 #define ISL1219_REG_EV  0x09
46 #define ISL1219_REG_EV_EVEN    (1<<4)   /* event detection enable */
47 #define ISL1219_REG_EV_EVIENB  (1<<7)   /* event in pull-up disable */
48 #define ISL1208_REG_ATR 0x0a
49 #define ISL1208_REG_DTR 0x0b
50 
51 /* alarm section */
52 #define ISL1208_REG_SCA 0x0c
53 #define ISL1208_REG_MNA 0x0d
54 #define ISL1208_REG_HRA 0x0e
55 #define ISL1208_REG_DTA 0x0f
56 #define ISL1208_REG_MOA 0x10
57 #define ISL1208_REG_DWA 0x11
58 #define ISL1208_ALARM_SECTION_LEN 6
59 
60 /* user section */
61 #define ISL1208_REG_USR1 0x12
62 #define ISL1208_REG_USR2 0x13
63 #define ISL1208_USR_SECTION_LEN 2
64 
65 /* event section */
66 #define ISL1219_REG_SCT 0x14
67 #define ISL1219_REG_MNT 0x15
68 #define ISL1219_REG_HRT 0x16
69 #define ISL1219_REG_DTT 0x17
70 #define ISL1219_REG_MOT 0x18
71 #define ISL1219_REG_YRT 0x19
72 #define ISL1219_EVT_SECTION_LEN 6
73 
74 static struct i2c_driver isl1208_driver;
75 
76 /* ISL1208 various variants */
77 enum {
78 	TYPE_ISL1208 = 0,
79 	TYPE_ISL1218,
80 	TYPE_ISL1219,
81 };
82 
83 /* block read */
84 static int
85 isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
86 		      unsigned len)
87 {
88 	u8 reg_addr[1] = { reg };
89 	struct i2c_msg msgs[2] = {
90 		{
91 			.addr = client->addr,
92 			.len = sizeof(reg_addr),
93 			.buf = reg_addr
94 		},
95 		{
96 			.addr = client->addr,
97 			.flags = I2C_M_RD,
98 			.len = len,
99 			.buf = buf
100 		}
101 	};
102 	int ret;
103 
104 	WARN_ON(reg > ISL1219_REG_YRT);
105 	WARN_ON(reg + len > ISL1219_REG_YRT + 1);
106 
107 	ret = i2c_transfer(client->adapter, msgs, 2);
108 	if (ret > 0)
109 		ret = 0;
110 	return ret;
111 }
112 
113 /* block write */
114 static int
115 isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
116 		     unsigned len)
117 {
118 	u8 i2c_buf[ISL1208_REG_USR2 + 2];
119 	struct i2c_msg msgs[1] = {
120 		{
121 			.addr = client->addr,
122 			.len = len + 1,
123 			.buf = i2c_buf
124 		}
125 	};
126 	int ret;
127 
128 	WARN_ON(reg > ISL1219_REG_YRT);
129 	WARN_ON(reg + len > ISL1219_REG_YRT + 1);
130 
131 	i2c_buf[0] = reg;
132 	memcpy(&i2c_buf[1], &buf[0], len);
133 
134 	ret = i2c_transfer(client->adapter, msgs, 1);
135 	if (ret > 0)
136 		ret = 0;
137 	return ret;
138 }
139 
140 /* simple check to see whether we have a isl1208 */
141 static int
142 isl1208_i2c_validate_client(struct i2c_client *client)
143 {
144 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
145 	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
146 		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
147 	};
148 	int i;
149 	int ret;
150 
151 	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
152 	if (ret < 0)
153 		return ret;
154 
155 	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
156 		if (regs[i] & zero_mask[i])	/* check if bits are cleared */
157 			return -ENODEV;
158 	}
159 
160 	return 0;
161 }
162 
163 static int
164 isl1208_i2c_get_sr(struct i2c_client *client)
165 {
166 	return i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
167 }
168 
169 static int
170 isl1208_i2c_get_atr(struct i2c_client *client)
171 {
172 	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
173 	if (atr < 0)
174 		return atr;
175 
176 	/* The 6bit value in the ATR register controls the load
177 	 * capacitance C_load * in steps of 0.25pF
178 	 *
179 	 * bit (1<<5) of the ATR register is inverted
180 	 *
181 	 * C_load(ATR=0x20) =  4.50pF
182 	 * C_load(ATR=0x00) = 12.50pF
183 	 * C_load(ATR=0x1f) = 20.25pF
184 	 *
185 	 */
186 
187 	atr &= 0x3f;		/* mask out lsb */
188 	atr ^= 1 << 5;		/* invert 6th bit */
189 	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */
190 
191 	return atr;
192 }
193 
194 static int
195 isl1208_i2c_get_dtr(struct i2c_client *client)
196 {
197 	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
198 	if (dtr < 0)
199 		return -EIO;
200 
201 	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
202 	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);
203 
204 	return dtr;
205 }
206 
207 static int
208 isl1208_i2c_get_usr(struct i2c_client *client)
209 {
210 	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
211 	int ret;
212 
213 	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
214 				    ISL1208_USR_SECTION_LEN);
215 	if (ret < 0)
216 		return ret;
217 
218 	return (buf[1] << 8) | buf[0];
219 }
220 
221 static int
222 isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
223 {
224 	u8 buf[ISL1208_USR_SECTION_LEN];
225 
226 	buf[0] = usr & 0xff;
227 	buf[1] = (usr >> 8) & 0xff;
228 
229 	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
230 				    ISL1208_USR_SECTION_LEN);
231 }
232 
233 static int
234 isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
235 {
236 	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
237 
238 	if (icr < 0) {
239 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
240 		return icr;
241 	}
242 
243 	if (enable)
244 		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
245 	else
246 		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
247 
248 	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
249 	if (icr < 0) {
250 		dev_err(&client->dev, "%s: writing INT failed\n", __func__);
251 		return icr;
252 	}
253 
254 	return 0;
255 }
256 
257 static int
258 isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
259 {
260 	struct i2c_client *const client = to_i2c_client(dev);
261 	int sr, dtr, atr, usr;
262 
263 	sr = isl1208_i2c_get_sr(client);
264 	if (sr < 0) {
265 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
266 		return sr;
267 	}
268 
269 	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
270 		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
271 		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
272 		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
273 		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
274 		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
275 		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);
276 
277 	seq_printf(seq, "batt_status\t: %s\n",
278 		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
279 
280 	dtr = isl1208_i2c_get_dtr(client);
281 	if (dtr >= 0 - 1)
282 		seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);
283 
284 	atr = isl1208_i2c_get_atr(client);
285 	if (atr >= 0)
286 		seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
287 			   atr >> 2, (atr & 0x3) * 25);
288 
289 	usr = isl1208_i2c_get_usr(client);
290 	if (usr >= 0)
291 		seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
292 
293 	return 0;
294 }
295 
296 static int
297 isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
298 {
299 	int sr;
300 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
301 
302 	sr = isl1208_i2c_get_sr(client);
303 	if (sr < 0) {
304 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
305 		return -EIO;
306 	}
307 
308 	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
309 	if (sr < 0) {
310 		dev_err(&client->dev, "%s: reading RTC section failed\n",
311 			__func__);
312 		return sr;
313 	}
314 
315 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
316 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);
317 
318 	/* HR field has a more complex interpretation */
319 	{
320 		const u8 _hr = regs[ISL1208_REG_HR];
321 		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */
322 			tm->tm_hour = bcd2bin(_hr & 0x3f);
323 		else {
324 			/* 12h format */
325 			tm->tm_hour = bcd2bin(_hr & 0x1f);
326 			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */
327 				tm->tm_hour += 12;
328 		}
329 	}
330 
331 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
332 	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
333 	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
334 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);
335 
336 	return 0;
337 }
338 
339 static int
340 isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
341 {
342 	struct rtc_time *const tm = &alarm->time;
343 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
344 	int icr, yr, sr = isl1208_i2c_get_sr(client);
345 
346 	if (sr < 0) {
347 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
348 		return sr;
349 	}
350 
351 	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
352 				   ISL1208_ALARM_SECTION_LEN);
353 	if (sr < 0) {
354 		dev_err(&client->dev, "%s: reading alarm section failed\n",
355 			__func__);
356 		return sr;
357 	}
358 
359 	/* MSB of each alarm register is an enable bit */
360 	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
361 	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
362 	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
363 	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
364 	tm->tm_mon =
365 		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
366 	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);
367 
368 	/* The alarm doesn't store the year so get it from the rtc section */
369 	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
370 	if (yr < 0) {
371 		dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
372 		return yr;
373 	}
374 	tm->tm_year = bcd2bin(yr) + 100;
375 
376 	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
377 	if (icr < 0) {
378 		dev_err(&client->dev, "%s: reading INT failed\n", __func__);
379 		return icr;
380 	}
381 	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
382 
383 	return 0;
384 }
385 
386 static int
387 isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
388 {
389 	struct rtc_time *alarm_tm = &alarm->time;
390 	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
391 	const int offs = ISL1208_REG_SCA;
392 	struct rtc_time rtc_tm;
393 	int err, enable;
394 
395 	err = isl1208_i2c_read_time(client, &rtc_tm);
396 	if (err)
397 		return err;
398 
399 	/* If the alarm time is before the current time disable the alarm */
400 	if (!alarm->enabled || rtc_tm_sub(alarm_tm, &rtc_tm) <= 0)
401 		enable = 0x00;
402 	else
403 		enable = 0x80;
404 
405 	/* Program the alarm and enable it for each setting */
406 	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
407 	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
408 	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
409 		ISL1208_REG_HR_MIL | enable;
410 
411 	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
412 	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
413 	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
414 
415 	/* write ALARM registers */
416 	err = isl1208_i2c_set_regs(client, offs, regs,
417 				  ISL1208_ALARM_SECTION_LEN);
418 	if (err < 0) {
419 		dev_err(&client->dev, "%s: writing ALARM section failed\n",
420 			__func__);
421 		return err;
422 	}
423 
424 	err = isl1208_rtc_toggle_alarm(client, enable);
425 	if (err)
426 		return err;
427 
428 	return 0;
429 }
430 
431 static int
432 isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
433 {
434 	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
435 }
436 
437 static int
438 isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
439 {
440 	int sr;
441 	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
442 
443 	/* The clock has an 8 bit wide bcd-coded register (they never learn)
444 	 * for the year. tm_year is an offset from 1900 and we are interested
445 	 * in the 2000-2099 range, so any value less than 100 is invalid.
446 	 */
447 	if (tm->tm_year < 100)
448 		return -EINVAL;
449 
450 	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
451 	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
452 	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;
453 
454 	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
455 	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
456 	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);
457 
458 	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);
459 
460 	sr = isl1208_i2c_get_sr(client);
461 	if (sr < 0) {
462 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
463 		return sr;
464 	}
465 
466 	/* set WRTC */
467 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
468 				       sr | ISL1208_REG_SR_WRTC);
469 	if (sr < 0) {
470 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
471 		return sr;
472 	}
473 
474 	/* write RTC registers */
475 	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
476 	if (sr < 0) {
477 		dev_err(&client->dev, "%s: writing RTC section failed\n",
478 			__func__);
479 		return sr;
480 	}
481 
482 	/* clear WRTC again */
483 	sr = isl1208_i2c_get_sr(client);
484 	if (sr < 0) {
485 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
486 		return sr;
487 	}
488 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
489 				       sr & ~ISL1208_REG_SR_WRTC);
490 	if (sr < 0) {
491 		dev_err(&client->dev, "%s: writing SR failed\n", __func__);
492 		return sr;
493 	}
494 
495 	return 0;
496 }
497 
498 
499 static int
500 isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
501 {
502 	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
503 }
504 
505 static int
506 isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
507 {
508 	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
509 }
510 
511 static int
512 isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
513 {
514 	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
515 }
516 
517 static ssize_t timestamp0_store(struct device *dev,
518 				struct device_attribute *attr,
519 				const char *buf, size_t count)
520 {
521 	struct i2c_client *client = dev_get_drvdata(dev);
522 	int sr;
523 
524 	sr = isl1208_i2c_get_sr(client);
525 	if (sr < 0) {
526 		dev_err(dev, "%s: reading SR failed\n", __func__);
527 		return sr;
528 	}
529 
530 	sr &= ~ISL1208_REG_SR_EVT;
531 
532 	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
533 	if (sr < 0)
534 		dev_err(dev, "%s: writing SR failed\n",
535 			__func__);
536 
537 	return count;
538 };
539 
540 static ssize_t timestamp0_show(struct device *dev,
541 			       struct device_attribute *attr, char *buf)
542 {
543 	struct i2c_client *client = dev_get_drvdata(dev);
544 	u8 regs[ISL1219_EVT_SECTION_LEN] = { 0, };
545 	struct rtc_time tm;
546 	int sr;
547 
548 	sr = isl1208_i2c_get_sr(client);
549 	if (sr < 0) {
550 		dev_err(dev, "%s: reading SR failed\n", __func__);
551 		return sr;
552 	}
553 
554 	if (!(sr & ISL1208_REG_SR_EVT))
555 		return 0;
556 
557 	sr = isl1208_i2c_read_regs(client, ISL1219_REG_SCT, regs,
558 				   ISL1219_EVT_SECTION_LEN);
559 	if (sr < 0) {
560 		dev_err(dev, "%s: reading event section failed\n",
561 			__func__);
562 		return 0;
563 	}
564 
565 	/* MSB of each alarm register is an enable bit */
566 	tm.tm_sec = bcd2bin(regs[ISL1219_REG_SCT - ISL1219_REG_SCT] & 0x7f);
567 	tm.tm_min = bcd2bin(regs[ISL1219_REG_MNT - ISL1219_REG_SCT] & 0x7f);
568 	tm.tm_hour = bcd2bin(regs[ISL1219_REG_HRT - ISL1219_REG_SCT] & 0x3f);
569 	tm.tm_mday = bcd2bin(regs[ISL1219_REG_DTT - ISL1219_REG_SCT] & 0x3f);
570 	tm.tm_mon =
571 		bcd2bin(regs[ISL1219_REG_MOT - ISL1219_REG_SCT] & 0x1f) - 1;
572 	tm.tm_year = bcd2bin(regs[ISL1219_REG_YRT - ISL1219_REG_SCT]) + 100;
573 
574 	sr = rtc_valid_tm(&tm);
575 	if (sr)
576 		return sr;
577 
578 	return sprintf(buf, "%llu\n",
579 				(unsigned long long)rtc_tm_to_time64(&tm));
580 };
581 
582 static DEVICE_ATTR_RW(timestamp0);
583 
584 static irqreturn_t
585 isl1208_rtc_interrupt(int irq, void *data)
586 {
587 	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
588 	struct i2c_client *client = data;
589 	struct rtc_device *rtc = i2c_get_clientdata(client);
590 	int handled = 0, sr, err;
591 
592 	/*
593 	 * I2C reads get NAK'ed if we read straight away after an interrupt?
594 	 * Using a mdelay/msleep didn't seem to help either, so we work around
595 	 * this by continually trying to read the register for a short time.
596 	 */
597 	while (1) {
598 		sr = isl1208_i2c_get_sr(client);
599 		if (sr >= 0)
600 			break;
601 
602 		if (time_after(jiffies, timeout)) {
603 			dev_err(&client->dev, "%s: reading SR failed\n",
604 				__func__);
605 			return sr;
606 		}
607 	}
608 
609 	if (sr & ISL1208_REG_SR_ALM) {
610 		dev_dbg(&client->dev, "alarm!\n");
611 
612 		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
613 
614 		/* Clear the alarm */
615 		sr &= ~ISL1208_REG_SR_ALM;
616 		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
617 		if (sr < 0)
618 			dev_err(&client->dev, "%s: writing SR failed\n",
619 				__func__);
620 		else
621 			handled = 1;
622 
623 		/* Disable the alarm */
624 		err = isl1208_rtc_toggle_alarm(client, 0);
625 		if (err)
626 			return err;
627 	}
628 
629 	if (sr & ISL1208_REG_SR_EVT) {
630 		sysfs_notify(&rtc->dev.kobj, NULL,
631 			     dev_attr_timestamp0.attr.name);
632 		dev_warn(&client->dev, "event detected");
633 		handled = 1;
634 	}
635 
636 	return handled ? IRQ_HANDLED : IRQ_NONE;
637 }
638 
639 static const struct rtc_class_ops isl1208_rtc_ops = {
640 	.proc = isl1208_rtc_proc,
641 	.read_time = isl1208_rtc_read_time,
642 	.set_time = isl1208_rtc_set_time,
643 	.read_alarm = isl1208_rtc_read_alarm,
644 	.set_alarm = isl1208_rtc_set_alarm,
645 };
646 
647 /* sysfs interface */
648 
649 static ssize_t
650 isl1208_sysfs_show_atrim(struct device *dev,
651 			 struct device_attribute *attr, char *buf)
652 {
653 	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
654 	if (atr < 0)
655 		return atr;
656 
657 	return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
658 }
659 
660 static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);
661 
662 static ssize_t
663 isl1208_sysfs_show_dtrim(struct device *dev,
664 			 struct device_attribute *attr, char *buf)
665 {
666 	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
667 	if (dtr < 0)
668 		return dtr;
669 
670 	return sprintf(buf, "%d ppm\n", dtr);
671 }
672 
673 static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);
674 
675 static ssize_t
676 isl1208_sysfs_show_usr(struct device *dev,
677 		       struct device_attribute *attr, char *buf)
678 {
679 	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
680 	if (usr < 0)
681 		return usr;
682 
683 	return sprintf(buf, "0x%.4x\n", usr);
684 }
685 
686 static ssize_t
687 isl1208_sysfs_store_usr(struct device *dev,
688 			struct device_attribute *attr,
689 			const char *buf, size_t count)
690 {
691 	int usr = -1;
692 
693 	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
694 		if (sscanf(buf, "%x", &usr) != 1)
695 			return -EINVAL;
696 	} else {
697 		if (sscanf(buf, "%d", &usr) != 1)
698 			return -EINVAL;
699 	}
700 
701 	if (usr < 0 || usr > 0xffff)
702 		return -EINVAL;
703 
704 	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
705 }
706 
707 static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
708 		   isl1208_sysfs_store_usr);
709 
710 static struct attribute *isl1208_rtc_attrs[] = {
711 	&dev_attr_atrim.attr,
712 	&dev_attr_dtrim.attr,
713 	&dev_attr_usr.attr,
714 	NULL
715 };
716 
717 static const struct attribute_group isl1208_rtc_sysfs_files = {
718 	.attrs	= isl1208_rtc_attrs,
719 };
720 
721 static struct attribute *isl1219_rtc_attrs[] = {
722 	&dev_attr_timestamp0.attr,
723 	NULL
724 };
725 
726 static const struct attribute_group isl1219_rtc_sysfs_files = {
727 	.attrs	= isl1219_rtc_attrs,
728 };
729 
730 static int isl1208_setup_irq(struct i2c_client *client, int irq)
731 {
732 	int rc = devm_request_threaded_irq(&client->dev, irq, NULL,
733 					isl1208_rtc_interrupt,
734 					IRQF_SHARED | IRQF_ONESHOT,
735 					isl1208_driver.driver.name,
736 					client);
737 	if (!rc) {
738 		device_init_wakeup(&client->dev, 1);
739 		enable_irq_wake(irq);
740 	} else {
741 		dev_err(&client->dev,
742 			"Unable to request irq %d, no alarm support\n",
743 			irq);
744 	}
745 	return rc;
746 }
747 
748 static int
749 isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
750 {
751 	int rc = 0;
752 	struct rtc_device *rtc;
753 	int evdet_irq = -1;
754 
755 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
756 		return -ENODEV;
757 
758 	if (isl1208_i2c_validate_client(client) < 0)
759 		return -ENODEV;
760 
761 	rtc = devm_rtc_allocate_device(&client->dev);
762 	if (IS_ERR(rtc))
763 		return PTR_ERR(rtc);
764 
765 	rtc->ops = &isl1208_rtc_ops;
766 
767 	i2c_set_clientdata(client, rtc);
768 	dev_set_drvdata(&rtc->dev, client);
769 
770 	rc = isl1208_i2c_get_sr(client);
771 	if (rc < 0) {
772 		dev_err(&client->dev, "reading status failed\n");
773 		return rc;
774 	}
775 
776 	if (rc & ISL1208_REG_SR_RTCF)
777 		dev_warn(&client->dev, "rtc power failure detected, "
778 			 "please set clock.\n");
779 
780 	if (id->driver_data == TYPE_ISL1219) {
781 		struct device_node *np = client->dev.of_node;
782 		u32 evienb;
783 
784 		rc = i2c_smbus_read_byte_data(client, ISL1219_REG_EV);
785 		if (rc < 0) {
786 			dev_err(&client->dev, "failed to read EV reg\n");
787 			return rc;
788 		}
789 		rc |= ISL1219_REG_EV_EVEN;
790 		if (!of_property_read_u32(np, "isil,ev-evienb", &evienb)) {
791 			if (evienb)
792 				rc |= ISL1219_REG_EV_EVIENB;
793 			else
794 				rc &= ~ISL1219_REG_EV_EVIENB;
795 		}
796 		rc = i2c_smbus_write_byte_data(client, ISL1219_REG_EV, rc);
797 		if (rc < 0) {
798 			dev_err(&client->dev, "could not enable tamper detection\n");
799 			return rc;
800 		}
801 		rc = rtc_add_group(rtc, &isl1219_rtc_sysfs_files);
802 		if (rc)
803 			return rc;
804 		evdet_irq = of_irq_get_byname(np, "evdet");
805 	}
806 
807 	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
808 	if (rc)
809 		return rc;
810 
811 	if (client->irq > 0)
812 		rc = isl1208_setup_irq(client, client->irq);
813 	if (rc)
814 		return rc;
815 
816 	if (evdet_irq > 0 && evdet_irq != client->irq)
817 		rc = isl1208_setup_irq(client, evdet_irq);
818 	if (rc)
819 		return rc;
820 
821 	return rtc_register_device(rtc);
822 }
823 
824 static int
825 isl1208_remove(struct i2c_client *client)
826 {
827 	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
828 
829 	return 0;
830 }
831 
832 static const struct i2c_device_id isl1208_id[] = {
833 	{ "isl1208", TYPE_ISL1208 },
834 	{ "isl1218", TYPE_ISL1218 },
835 	{ "isl1219", TYPE_ISL1219 },
836 	{ }
837 };
838 MODULE_DEVICE_TABLE(i2c, isl1208_id);
839 
840 static const struct of_device_id isl1208_of_match[] = {
841 	{ .compatible = "isil,isl1208" },
842 	{ .compatible = "isil,isl1218" },
843 	{ .compatible = "isil,isl1219" },
844 	{ }
845 };
846 MODULE_DEVICE_TABLE(of, isl1208_of_match);
847 
848 static struct i2c_driver isl1208_driver = {
849 	.driver = {
850 		.name = "rtc-isl1208",
851 		.of_match_table = of_match_ptr(isl1208_of_match),
852 	},
853 	.probe = isl1208_probe,
854 	.remove = isl1208_remove,
855 	.id_table = isl1208_id,
856 };
857 
858 module_i2c_driver(isl1208_driver);
859 
860 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
861 MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
862 MODULE_LICENSE("GPL");
863