xref: /linux/drivers/rtc/rtc-isl12022.c (revision 0e287d31b62bb53ad81d5e59778384a40f8b6f56)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An I2C driver for the Intersil ISL 12022
4  *
5  * Author: Roman Fietze <roman.fietze@telemotive.de>
6  *
7  * Based on the Philips PCF8563 RTC
8  * by Alessandro Zummo <a.zummo@towertech.it>.
9  */
10 
11 #include <linux/bcd.h>
12 #include <linux/bitfield.h>
13 #include <linux/clk-provider.h>
14 #include <linux/err.h>
15 #include <linux/hwmon.h>
16 #include <linux/i2c.h>
17 #include <linux/module.h>
18 #include <linux/regmap.h>
19 #include <linux/rtc.h>
20 #include <linux/slab.h>
21 
22 #include <asm/byteorder.h>
23 
24 /* RTC - Real time clock registers */
25 #define ISL12022_REG_SC		0x00
26 #define ISL12022_REG_MN		0x01
27 #define ISL12022_REG_HR		0x02
28 #define ISL12022_REG_DT		0x03
29 #define ISL12022_REG_MO		0x04
30 #define ISL12022_REG_YR		0x05
31 #define ISL12022_REG_DW		0x06
32 
33 /* CSR - Control and status registers */
34 #define ISL12022_REG_SR		0x07
35 #define ISL12022_REG_INT	0x08
36 #define ISL12022_REG_PWR_VBAT	0x0a
37 #define ISL12022_REG_BETA	0x0d
38 
39 /* ALARM - Alarm registers */
40 #define ISL12022_REG_SCA0	0x10
41 #define ISL12022_REG_MNA0	0x11
42 #define ISL12022_REG_HRA0	0x12
43 #define ISL12022_REG_DTA0	0x13
44 #define ISL12022_REG_MOA0	0x14
45 #define ISL12022_REG_DWA0	0x15
46 #define ISL12022_ALARM		ISL12022_REG_SCA0
47 #define ISL12022_ALARM_LEN	(ISL12022_REG_DWA0 - ISL12022_REG_SCA0 + 1)
48 
49 /* TEMP - Temperature sensor registers */
50 #define ISL12022_REG_TEMP_L	0x28
51 
52 /* ISL register bits */
53 #define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
54 
55 #define ISL12022_SR_ALM		(1 << 4)
56 #define ISL12022_SR_LBAT85	(1 << 2)
57 #define ISL12022_SR_LBAT75	(1 << 1)
58 
59 #define ISL12022_INT_ARST	(1 << 7)
60 #define ISL12022_INT_WRTC	(1 << 6)
61 #define ISL12022_INT_IM		(1 << 5)
62 #define ISL12022_INT_FOBATB	(1 << 4)
63 #define ISL12022_INT_FO_MASK	GENMASK(3, 0)
64 #define ISL12022_INT_FO_OFF	0x0
65 #define ISL12022_INT_FO_32K	0x1
66 
67 #define ISL12022_REG_VB85_MASK	GENMASK(5, 3)
68 #define ISL12022_REG_VB75_MASK	GENMASK(2, 0)
69 
70 #define ISL12022_ALARM_ENABLE	(1 << 7)	/* for all ALARM registers  */
71 
72 #define ISL12022_BETA_TSE	(1 << 7)
73 
74 static struct i2c_driver isl12022_driver;
75 
76 struct isl12022 {
77 	struct rtc_device *rtc;
78 	struct regmap *regmap;
79 	int irq;
80 	bool irq_enabled;
81 };
82 
isl12022_hwmon_is_visible(const void * data,enum hwmon_sensor_types type,u32 attr,int channel)83 static umode_t isl12022_hwmon_is_visible(const void *data,
84 					 enum hwmon_sensor_types type,
85 					 u32 attr, int channel)
86 {
87 	if (type == hwmon_temp && attr == hwmon_temp_input)
88 		return 0444;
89 
90 	return 0;
91 }
92 
93 /*
94  * A user-initiated temperature conversion is not started by this function,
95  * so the temperature is updated once every ~60 seconds.
96  */
isl12022_hwmon_read_temp(struct device * dev,long * mC)97 static int isl12022_hwmon_read_temp(struct device *dev, long *mC)
98 {
99 	struct regmap *regmap = dev_get_drvdata(dev);
100 	int temp, ret;
101 	__le16 buf;
102 
103 	ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L, &buf, sizeof(buf));
104 	if (ret)
105 		return ret;
106 	/*
107 	 * Temperature is represented as a 10-bit number, unit half-Kelvins.
108 	 */
109 	temp = le16_to_cpu(buf);
110 	temp *= 500;
111 	temp -= 273000;
112 
113 	*mC = temp;
114 
115 	return 0;
116 }
117 
isl12022_hwmon_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)118 static int isl12022_hwmon_read(struct device *dev,
119 			       enum hwmon_sensor_types type,
120 			       u32 attr, int channel, long *val)
121 {
122 	if (type == hwmon_temp && attr == hwmon_temp_input)
123 		return isl12022_hwmon_read_temp(dev, val);
124 
125 	return -EOPNOTSUPP;
126 }
127 
128 static const struct hwmon_channel_info * const isl12022_hwmon_info[] = {
129 	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
130 	NULL
131 };
132 
133 static const struct hwmon_ops isl12022_hwmon_ops = {
134 	.is_visible = isl12022_hwmon_is_visible,
135 	.read = isl12022_hwmon_read,
136 };
137 
138 static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
139 	.ops = &isl12022_hwmon_ops,
140 	.info = isl12022_hwmon_info,
141 };
142 
isl12022_hwmon_register(struct device * dev)143 static void isl12022_hwmon_register(struct device *dev)
144 {
145 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
146 	struct regmap *regmap = isl12022->regmap;
147 	struct device *hwmon;
148 	int ret;
149 
150 	if (!IS_REACHABLE(CONFIG_HWMON))
151 		return;
152 
153 	ret = regmap_update_bits(regmap, ISL12022_REG_BETA,
154 				 ISL12022_BETA_TSE, ISL12022_BETA_TSE);
155 	if (ret) {
156 		dev_warn(dev, "unable to enable temperature sensor\n");
157 		return;
158 	}
159 
160 	hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", regmap,
161 						     &isl12022_hwmon_chip_info,
162 						     NULL);
163 	if (IS_ERR(hwmon))
164 		dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
165 }
166 
167 /*
168  * In the routines that deal directly with the isl12022 hardware, we use
169  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
170  */
isl12022_rtc_read_time(struct device * dev,struct rtc_time * tm)171 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
172 {
173 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
174 	struct regmap *regmap = isl12022->regmap;
175 	u8 buf[ISL12022_REG_INT + 1];
176 	int ret;
177 
178 	ret = regmap_bulk_read(regmap, ISL12022_REG_SC, buf, sizeof(buf));
179 	if (ret)
180 		return ret;
181 
182 	dev_dbg(dev,
183 		"raw data is sec=%02x, min=%02x, hr=%02x, mday=%02x, mon=%02x, year=%02x, wday=%02x, sr=%02x, int=%02x",
184 		buf[ISL12022_REG_SC],
185 		buf[ISL12022_REG_MN],
186 		buf[ISL12022_REG_HR],
187 		buf[ISL12022_REG_DT],
188 		buf[ISL12022_REG_MO],
189 		buf[ISL12022_REG_YR],
190 		buf[ISL12022_REG_DW],
191 		buf[ISL12022_REG_SR],
192 		buf[ISL12022_REG_INT]);
193 
194 	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
195 	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
196 	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
197 	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
198 	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
199 	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
200 	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
201 
202 	dev_dbg(dev, "%s: %ptR\n", __func__, tm);
203 
204 	return 0;
205 }
206 
isl12022_rtc_set_time(struct device * dev,struct rtc_time * tm)207 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
208 {
209 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
210 	struct regmap *regmap = isl12022->regmap;
211 	int ret;
212 	u8 buf[ISL12022_REG_DW + 1];
213 
214 	dev_dbg(dev, "%s: %ptR\n", __func__, tm);
215 
216 	/* Ensure the write enable bit is set. */
217 	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
218 				 ISL12022_INT_WRTC, ISL12022_INT_WRTC);
219 	if (ret)
220 		return ret;
221 
222 	/* hours, minutes and seconds */
223 	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
224 	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
225 	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
226 
227 	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
228 
229 	/* month, 1 - 12 */
230 	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
231 
232 	/* year and century */
233 	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
234 
235 	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
236 
237 	return regmap_bulk_write(regmap, ISL12022_REG_SC, buf, sizeof(buf));
238 }
239 
isl12022_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)240 static int isl12022_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
241 {
242 	struct rtc_time *tm = &alarm->time;
243 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
244 	struct regmap *regmap = isl12022->regmap;
245 	u8 buf[ISL12022_ALARM_LEN];
246 	unsigned int i, yr;
247 	int ret;
248 
249 	ret = regmap_bulk_read(regmap, ISL12022_ALARM, buf, sizeof(buf));
250 	if (ret) {
251 		dev_dbg(dev, "%s: reading ALARM registers failed\n",
252 			__func__);
253 		return ret;
254 	}
255 
256 	/* The alarm doesn't store the year so get it from the rtc section */
257 	ret = regmap_read(regmap, ISL12022_REG_YR, &yr);
258 	if (ret) {
259 		dev_dbg(dev, "%s: reading YR register failed\n", __func__);
260 		return ret;
261 	}
262 
263 	dev_dbg(dev,
264 		"%s: sc=%02x, mn=%02x, hr=%02x, dt=%02x, mo=%02x, dw=%02x yr=%u\n",
265 		__func__, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], yr);
266 
267 	tm->tm_sec  = bcd2bin(buf[ISL12022_REG_SCA0 - ISL12022_ALARM] & 0x7F);
268 	tm->tm_min  = bcd2bin(buf[ISL12022_REG_MNA0 - ISL12022_ALARM] & 0x7F);
269 	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HRA0 - ISL12022_ALARM] & 0x3F);
270 	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DTA0 - ISL12022_ALARM] & 0x3F);
271 	tm->tm_mon  = bcd2bin(buf[ISL12022_REG_MOA0 - ISL12022_ALARM] & 0x1F) - 1;
272 	tm->tm_wday = buf[ISL12022_REG_DWA0 - ISL12022_ALARM]         & 0x07;
273 	tm->tm_year = bcd2bin(yr) + 100;
274 
275 	for (i = 0; i < ISL12022_ALARM_LEN; i++) {
276 		if (buf[i] & ISL12022_ALARM_ENABLE) {
277 			alarm->enabled = 1;
278 			break;
279 		}
280 	}
281 
282 	dev_dbg(dev, "%s: %ptR\n", __func__, tm);
283 
284 	return 0;
285 }
286 
isl12022_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)287 static int isl12022_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
288 {
289 	struct rtc_time *alarm_tm = &alarm->time;
290 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
291 	struct regmap *regmap = isl12022->regmap;
292 	u8 regs[ISL12022_ALARM_LEN] = { 0, };
293 	struct rtc_time rtc_tm;
294 	int ret, enable, dw;
295 
296 	ret = isl12022_rtc_read_time(dev, &rtc_tm);
297 	if (ret)
298 		return ret;
299 
300 	/* If the alarm time is before the current time disable the alarm */
301 	if (!alarm->enabled || rtc_tm_sub(alarm_tm, &rtc_tm) <= 0)
302 		enable = 0;
303 	else
304 		enable = ISL12022_ALARM_ENABLE;
305 
306 	/*
307 	 * Set non-matching day of the week to safeguard against early false
308 	 * matching while setting all the alarm registers (this rtc lacks a
309 	 * general alarm/irq enable/disable bit).
310 	 */
311 	ret = regmap_read(regmap, ISL12022_REG_DW, &dw);
312 	if (ret) {
313 		dev_dbg(dev, "%s: reading DW failed\n", __func__);
314 		return ret;
315 	}
316 	/* ~4 days into the future should be enough to avoid match */
317 	dw = ((dw + 4) % 7) | ISL12022_ALARM_ENABLE;
318 	ret = regmap_write(regmap, ISL12022_REG_DWA0, dw);
319 	if (ret) {
320 		dev_dbg(dev, "%s: writing DWA0 failed\n", __func__);
321 		return ret;
322 	}
323 
324 	/* Program the alarm and enable it for each setting */
325 	regs[ISL12022_REG_SCA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_sec) | enable;
326 	regs[ISL12022_REG_MNA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_min) | enable;
327 	regs[ISL12022_REG_HRA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_hour) | enable;
328 	regs[ISL12022_REG_DTA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_mday) | enable;
329 	regs[ISL12022_REG_MOA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
330 	regs[ISL12022_REG_DWA0 - ISL12022_ALARM] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
331 
332 	/* write ALARM registers */
333 	ret = regmap_bulk_write(regmap, ISL12022_ALARM, &regs, sizeof(regs));
334 	if (ret) {
335 		dev_dbg(dev, "%s: writing ALARM registers failed\n", __func__);
336 		return ret;
337 	}
338 
339 	return 0;
340 }
341 
isl12022_rtc_interrupt(int irq,void * data)342 static irqreturn_t isl12022_rtc_interrupt(int irq, void *data)
343 {
344 	struct isl12022 *isl12022 = data;
345 	struct rtc_device *rtc = isl12022->rtc;
346 	struct device *dev = &rtc->dev;
347 	struct regmap *regmap = isl12022->regmap;
348 	u32 val = 0;
349 	unsigned long events = 0;
350 	int ret;
351 
352 	ret = regmap_read(regmap, ISL12022_REG_SR, &val);
353 	if (ret) {
354 		dev_dbg(dev, "%s: reading SR failed\n", __func__);
355 		return IRQ_HANDLED;
356 	}
357 
358 	if (val & ISL12022_SR_ALM)
359 		events |= RTC_IRQF | RTC_AF;
360 
361 	if (events & RTC_AF)
362 		dev_dbg(dev, "alarm!\n");
363 
364 	if (!events)
365 		return IRQ_NONE;
366 
367 	rtc_update_irq(rtc, 1, events);
368 	return IRQ_HANDLED;
369 }
370 
isl12022_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)371 static int isl12022_rtc_alarm_irq_enable(struct device *dev,
372 					 unsigned int enabled)
373 {
374 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
375 
376 	/* Make sure enabled is 0 or 1 */
377 	enabled = !!enabled;
378 
379 	if (isl12022->irq_enabled == enabled)
380 		return 0;
381 
382 	if (enabled)
383 		enable_irq(isl12022->irq);
384 	else
385 		disable_irq(isl12022->irq);
386 
387 	isl12022->irq_enabled = enabled;
388 
389 	return 0;
390 }
391 
isl12022_setup_irq(struct device * dev,int irq)392 static int isl12022_setup_irq(struct device *dev, int irq)
393 {
394 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
395 	struct regmap *regmap = isl12022->regmap;
396 	unsigned int reg_mask, reg_val;
397 	u8 buf[ISL12022_ALARM_LEN] = { 0, };
398 	int ret;
399 
400 	/* Clear and disable all alarm registers */
401 	ret = regmap_bulk_write(regmap, ISL12022_ALARM, buf, sizeof(buf));
402 	if (ret)
403 		return ret;
404 
405 	/*
406 	 * Enable automatic reset of ALM bit and enable single event interrupt
407 	 * mode.
408 	 */
409 	reg_mask = ISL12022_INT_ARST | ISL12022_INT_IM | ISL12022_INT_FO_MASK;
410 	reg_val = ISL12022_INT_ARST | ISL12022_INT_FO_OFF;
411 	ret = regmap_write_bits(regmap, ISL12022_REG_INT,
412 				reg_mask, reg_val);
413 	if (ret)
414 		return ret;
415 
416 	ret = devm_request_threaded_irq(dev, irq, NULL,
417 					isl12022_rtc_interrupt,
418 					IRQF_SHARED | IRQF_ONESHOT,
419 					isl12022_driver.driver.name,
420 					isl12022);
421 	if (ret)
422 		return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
423 
424 	isl12022->irq = irq;
425 	return 0;
426 }
427 
isl12022_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)428 static int isl12022_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
429 {
430 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
431 	struct regmap *regmap = isl12022->regmap;
432 	u32 user, val;
433 	int ret;
434 
435 	switch (cmd) {
436 	case RTC_VL_READ:
437 		ret = regmap_read(regmap, ISL12022_REG_SR, &val);
438 		if (ret)
439 			return ret;
440 
441 		user = 0;
442 		if (val & ISL12022_SR_LBAT85)
443 			user |= RTC_VL_BACKUP_LOW;
444 
445 		if (val & ISL12022_SR_LBAT75)
446 			user |= RTC_VL_BACKUP_EMPTY;
447 
448 		return put_user(user, (u32 __user *)arg);
449 
450 	default:
451 		return -ENOIOCTLCMD;
452 	}
453 }
454 
455 static const struct rtc_class_ops isl12022_rtc_ops = {
456 	.ioctl		= isl12022_rtc_ioctl,
457 	.read_time	= isl12022_rtc_read_time,
458 	.set_time	= isl12022_rtc_set_time,
459 	.read_alarm	= isl12022_rtc_read_alarm,
460 	.set_alarm	= isl12022_rtc_set_alarm,
461 	.alarm_irq_enable = isl12022_rtc_alarm_irq_enable,
462 };
463 
464 static const struct regmap_config regmap_config = {
465 	.reg_bits = 8,
466 	.val_bits = 8,
467 	.use_single_write = true,
468 };
469 
isl12022_register_clock(struct device * dev)470 static int isl12022_register_clock(struct device *dev)
471 {
472 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
473 	struct regmap *regmap = isl12022->regmap;
474 	struct clk_hw *hw;
475 	int ret;
476 
477 	if (!device_property_present(dev, "#clock-cells")) {
478 		/*
479 		 * Disabling the F_OUT pin reduces the power
480 		 * consumption in battery mode by ~25%.
481 		 */
482 		regmap_update_bits(regmap, ISL12022_REG_INT, ISL12022_INT_FO_MASK,
483 				   ISL12022_INT_FO_OFF);
484 
485 		return 0;
486 	}
487 
488 	if (!IS_ENABLED(CONFIG_COMMON_CLK))
489 		return 0;
490 
491 	/*
492 	 * For now, only support a fixed clock of 32768Hz (the reset default).
493 	 */
494 	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
495 				 ISL12022_INT_FO_MASK, ISL12022_INT_FO_32K);
496 	if (ret)
497 		return ret;
498 
499 	hw = devm_clk_hw_register_fixed_rate(dev, "isl12022", NULL, 0, 32768);
500 	if (IS_ERR(hw))
501 		return PTR_ERR(hw);
502 
503 	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
504 }
505 
506 static const u32 trip_levels[2][7] = {
507 	{ 2125000, 2295000, 2550000, 2805000, 3060000, 4250000, 4675000 },
508 	{ 1875000, 2025000, 2250000, 2475000, 2700000, 3750000, 4125000 },
509 };
510 
isl12022_set_trip_levels(struct device * dev)511 static void isl12022_set_trip_levels(struct device *dev)
512 {
513 	struct isl12022 *isl12022 = dev_get_drvdata(dev);
514 	struct regmap *regmap = isl12022->regmap;
515 	u32 levels[2] = {0, 0};
516 	int ret, i, j, x[2];
517 	u8 val, mask;
518 
519 	device_property_read_u32_array(dev, "isil,battery-trip-levels-microvolt",
520 				       levels, 2);
521 
522 	for (i = 0; i < 2; i++) {
523 		for (j = 0; j < ARRAY_SIZE(trip_levels[i]) - 1; j++) {
524 			if (levels[i] <= trip_levels[i][j])
525 				break;
526 		}
527 		x[i] = j;
528 	}
529 
530 	val = FIELD_PREP(ISL12022_REG_VB85_MASK, x[0]) |
531 		FIELD_PREP(ISL12022_REG_VB75_MASK, x[1]);
532 	mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK;
533 
534 	ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
535 	if (ret)
536 		dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);
537 
538 	/*
539 	 * Force a write of the TSE bit in the BETA register, in order
540 	 * to trigger an update of the LBAT75 and LBAT85 bits in the
541 	 * status register. In battery backup mode, those bits have
542 	 * another meaning, so without this, they may contain stale
543 	 * values for up to a minute after power-on.
544 	 */
545 	regmap_write_bits(regmap, ISL12022_REG_BETA,
546 			  ISL12022_BETA_TSE, ISL12022_BETA_TSE);
547 }
548 
isl12022_probe(struct i2c_client * client)549 static int isl12022_probe(struct i2c_client *client)
550 {
551 	struct isl12022 *isl12022;
552 	struct rtc_device *rtc;
553 	struct regmap *regmap;
554 	int ret;
555 
556 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
557 		return -ENODEV;
558 
559 	/* Allocate driver state */
560 	isl12022 = devm_kzalloc(&client->dev, sizeof(*isl12022), GFP_KERNEL);
561 	if (!isl12022)
562 		return -ENOMEM;
563 
564 	regmap = devm_regmap_init_i2c(client, &regmap_config);
565 	if (IS_ERR(regmap))
566 		return dev_err_probe(&client->dev, PTR_ERR(regmap), "regmap allocation failed\n");
567 	isl12022->regmap = regmap;
568 
569 	dev_set_drvdata(&client->dev, isl12022);
570 
571 	ret = isl12022_register_clock(&client->dev);
572 	if (ret)
573 		return ret;
574 
575 	isl12022_set_trip_levels(&client->dev);
576 	isl12022_hwmon_register(&client->dev);
577 
578 	rtc = devm_rtc_allocate_device(&client->dev);
579 	if (IS_ERR(rtc))
580 		return PTR_ERR(rtc);
581 	isl12022->rtc = rtc;
582 
583 	rtc->ops = &isl12022_rtc_ops;
584 	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
585 	rtc->range_max = RTC_TIMESTAMP_END_2099;
586 
587 	if (client->irq > 0) {
588 		ret = isl12022_setup_irq(&client->dev, client->irq);
589 		if (ret)
590 			return ret;
591 	} else {
592 		clear_bit(RTC_FEATURE_ALARM, rtc->features);
593 	}
594 
595 	return devm_rtc_register_device(rtc);
596 }
597 
598 static const struct of_device_id isl12022_dt_match[] = {
599 	{ .compatible = "isl,isl12022" }, /* for backward compat., don't use */
600 	{ .compatible = "isil,isl12022" },
601 	{ },
602 };
603 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
604 
605 static const struct i2c_device_id isl12022_id[] = {
606 	{ "isl12022" },
607 	{ }
608 };
609 MODULE_DEVICE_TABLE(i2c, isl12022_id);
610 
611 static struct i2c_driver isl12022_driver = {
612 	.driver		= {
613 		.name	= "rtc-isl12022",
614 		.of_match_table = isl12022_dt_match,
615 	},
616 	.probe		= isl12022_probe,
617 	.id_table	= isl12022_id,
618 };
619 
620 module_i2c_driver(isl12022_driver);
621 
622 MODULE_AUTHOR("roman.fietze@telemotive.de");
623 MODULE_DESCRIPTION("ISL 12022 RTC driver");
624 MODULE_LICENSE("GPL");
625