1 /*
2  * Copyright (C) ST-Ericsson SA 2010
3  *
4  * License terms: GNU General Public License (GPL) version 2
5  * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
6  *
7  * RTC clock driver for the RTC part of the AB8500 Power management chip.
8  * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
9  * Linus Walleij <linus.walleij@stericsson.com>
10  */
11 
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/platform_device.h>
16 #include <linux/rtc.h>
17 #include <linux/mfd/abx500.h>
18 #include <linux/mfd/abx500/ab8500.h>
19 #include <linux/delay.h>
20 #include <linux/of.h>
21 #include <linux/pm_wakeirq.h>
22 
23 #define AB8500_RTC_SOFF_STAT_REG	0x00
24 #define AB8500_RTC_CC_CONF_REG		0x01
25 #define AB8500_RTC_READ_REQ_REG		0x02
26 #define AB8500_RTC_WATCH_TSECMID_REG	0x03
27 #define AB8500_RTC_WATCH_TSECHI_REG	0x04
28 #define AB8500_RTC_WATCH_TMIN_LOW_REG	0x05
29 #define AB8500_RTC_WATCH_TMIN_MID_REG	0x06
30 #define AB8500_RTC_WATCH_TMIN_HI_REG	0x07
31 #define AB8500_RTC_ALRM_MIN_LOW_REG	0x08
32 #define AB8500_RTC_ALRM_MIN_MID_REG	0x09
33 #define AB8500_RTC_ALRM_MIN_HI_REG	0x0A
34 #define AB8500_RTC_STAT_REG		0x0B
35 #define AB8500_RTC_BKUP_CHG_REG		0x0C
36 #define AB8500_RTC_FORCE_BKUP_REG	0x0D
37 #define AB8500_RTC_CALIB_REG		0x0E
38 #define AB8500_RTC_SWITCH_STAT_REG	0x0F
39 
40 /* RtcReadRequest bits */
41 #define RTC_READ_REQUEST		0x01
42 #define RTC_WRITE_REQUEST		0x02
43 
44 /* RtcCtrl bits */
45 #define RTC_ALARM_ENA			0x04
46 #define RTC_STATUS_DATA			0x01
47 
48 #define COUNTS_PER_SEC			(0xF000 / 60)
49 #define AB8500_RTC_EPOCH		2000
50 
51 static const u8 ab8500_rtc_time_regs[] = {
52 	AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
53 	AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
54 	AB8500_RTC_WATCH_TSECMID_REG
55 };
56 
57 static const u8 ab8500_rtc_alarm_regs[] = {
58 	AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
59 	AB8500_RTC_ALRM_MIN_LOW_REG
60 };
61 
62 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
get_elapsed_seconds(int year)63 static unsigned long get_elapsed_seconds(int year)
64 {
65 	unsigned long secs;
66 	struct rtc_time tm = {
67 		.tm_year = year - 1900,
68 		.tm_mday = 1,
69 	};
70 
71 	/*
72 	 * This function calculates secs from 1970 and not from
73 	 * 1900, even if we supply the offset from year 1900.
74 	 */
75 	rtc_tm_to_time(&tm, &secs);
76 	return secs;
77 }
78 
ab8500_rtc_read_time(struct device * dev,struct rtc_time * tm)79 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
80 {
81 	unsigned long timeout = jiffies + HZ;
82 	int retval, i;
83 	unsigned long mins, secs;
84 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
85 	u8 value;
86 
87 	/* Request a data read */
88 	retval = abx500_set_register_interruptible(dev,
89 		AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
90 	if (retval < 0)
91 		return retval;
92 
93 	/* Wait for some cycles after enabling the rtc read in ab8500 */
94 	while (time_before(jiffies, timeout)) {
95 		retval = abx500_get_register_interruptible(dev,
96 			AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
97 		if (retval < 0)
98 			return retval;
99 
100 		if (!(value & RTC_READ_REQUEST))
101 			break;
102 
103 		usleep_range(1000, 5000);
104 	}
105 
106 	/* Read the Watchtime registers */
107 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
108 		retval = abx500_get_register_interruptible(dev,
109 			AB8500_RTC, ab8500_rtc_time_regs[i], &value);
110 		if (retval < 0)
111 			return retval;
112 		buf[i] = value;
113 	}
114 
115 	mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
116 
117 	secs =	(buf[3] << 8) | buf[4];
118 	secs =	secs / COUNTS_PER_SEC;
119 	secs =	secs + (mins * 60);
120 
121 	/* Add back the initially subtracted number of seconds */
122 	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
123 
124 	rtc_time_to_tm(secs, tm);
125 	return 0;
126 }
127 
ab8500_rtc_set_time(struct device * dev,struct rtc_time * tm)128 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
129 {
130 	int retval, i;
131 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
132 	unsigned long no_secs, no_mins, secs = 0;
133 
134 	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
135 		dev_dbg(dev, "year should be equal to or greater than %d\n",
136 				AB8500_RTC_EPOCH);
137 		return -EINVAL;
138 	}
139 
140 	/* Get the number of seconds since 1970 */
141 	rtc_tm_to_time(tm, &secs);
142 
143 	/*
144 	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
145 	 * we only have a small counter in the RTC.
146 	 */
147 	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
148 
149 	no_mins = secs / 60;
150 
151 	no_secs = secs % 60;
152 	/* Make the seconds count as per the RTC resolution */
153 	no_secs = no_secs * COUNTS_PER_SEC;
154 
155 	buf[4] = no_secs & 0xFF;
156 	buf[3] = (no_secs >> 8) & 0xFF;
157 
158 	buf[2] = no_mins & 0xFF;
159 	buf[1] = (no_mins >> 8) & 0xFF;
160 	buf[0] = (no_mins >> 16) & 0xFF;
161 
162 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
163 		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
164 			ab8500_rtc_time_regs[i], buf[i]);
165 		if (retval < 0)
166 			return retval;
167 	}
168 
169 	/* Request a data write */
170 	return abx500_set_register_interruptible(dev, AB8500_RTC,
171 		AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
172 }
173 
ab8500_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)174 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
175 {
176 	int retval, i;
177 	u8 rtc_ctrl, value;
178 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
179 	unsigned long secs, mins;
180 
181 	/* Check if the alarm is enabled or not */
182 	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
183 		AB8500_RTC_STAT_REG, &rtc_ctrl);
184 	if (retval < 0)
185 		return retval;
186 
187 	if (rtc_ctrl & RTC_ALARM_ENA)
188 		alarm->enabled = 1;
189 	else
190 		alarm->enabled = 0;
191 
192 	alarm->pending = 0;
193 
194 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
195 		retval = abx500_get_register_interruptible(dev, AB8500_RTC,
196 			ab8500_rtc_alarm_regs[i], &value);
197 		if (retval < 0)
198 			return retval;
199 		buf[i] = value;
200 	}
201 
202 	mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
203 	secs = mins * 60;
204 
205 	/* Add back the initially subtracted number of seconds */
206 	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
207 
208 	rtc_time_to_tm(secs, &alarm->time);
209 
210 	return rtc_valid_tm(&alarm->time);
211 }
212 
ab8500_rtc_irq_enable(struct device * dev,unsigned int enabled)213 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
214 {
215 	return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
216 		AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
217 		enabled ? RTC_ALARM_ENA : 0);
218 }
219 
ab8500_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)220 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
221 {
222 	int retval, i;
223 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
224 	unsigned long mins, secs = 0, cursec = 0;
225 	struct rtc_time curtm;
226 
227 	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
228 		dev_dbg(dev, "year should be equal to or greater than %d\n",
229 				AB8500_RTC_EPOCH);
230 		return -EINVAL;
231 	}
232 
233 	/* Get the number of seconds since 1970 */
234 	rtc_tm_to_time(&alarm->time, &secs);
235 
236 	/*
237 	 * Check whether alarm is set less than 1min.
238 	 * Since our RTC doesn't support alarm resolution less than 1min,
239 	 * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
240 	 */
241 	ab8500_rtc_read_time(dev, &curtm); /* Read current time */
242 	rtc_tm_to_time(&curtm, &cursec);
243 	if ((secs - cursec) < 59) {
244 		dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
245 		return -EINVAL;
246 	}
247 
248 	/*
249 	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
250 	 * we only have a small counter in the RTC.
251 	 */
252 	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
253 
254 	mins = secs / 60;
255 
256 	buf[2] = mins & 0xFF;
257 	buf[1] = (mins >> 8) & 0xFF;
258 	buf[0] = (mins >> 16) & 0xFF;
259 
260 	/* Set the alarm time */
261 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
262 		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
263 			ab8500_rtc_alarm_regs[i], buf[i]);
264 		if (retval < 0)
265 			return retval;
266 	}
267 
268 	return ab8500_rtc_irq_enable(dev, alarm->enabled);
269 }
270 
ab8500_rtc_set_calibration(struct device * dev,int calibration)271 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
272 {
273 	int retval;
274 	u8  rtccal = 0;
275 
276 	/*
277 	 * Check that the calibration value (which is in units of 0.5
278 	 * parts-per-million) is in the AB8500's range for RtcCalibration
279 	 * register. -128 (0x80) is not permitted because the AB8500 uses
280 	 * a sign-bit rather than two's complement, so 0x80 is just another
281 	 * representation of zero.
282 	 */
283 	if ((calibration < -127) || (calibration > 127)) {
284 		dev_err(dev, "RtcCalibration value outside permitted range\n");
285 		return -EINVAL;
286 	}
287 
288 	/*
289 	 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
290 	 * so need to convert to this sort of representation before writing
291 	 * into RtcCalibration register...
292 	 */
293 	if (calibration >= 0)
294 		rtccal = 0x7F & calibration;
295 	else
296 		rtccal = ~(calibration - 1) | 0x80;
297 
298 	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
299 			AB8500_RTC_CALIB_REG, rtccal);
300 
301 	return retval;
302 }
303 
ab8500_rtc_get_calibration(struct device * dev,int * calibration)304 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
305 {
306 	int retval;
307 	u8  rtccal = 0;
308 
309 	retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
310 			AB8500_RTC_CALIB_REG, &rtccal);
311 	if (retval >= 0) {
312 		/*
313 		 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
314 		 * so need to convert value from RtcCalibration register into
315 		 * a two's complement signed value...
316 		 */
317 		if (rtccal & 0x80)
318 			*calibration = 0 - (rtccal & 0x7F);
319 		else
320 			*calibration = 0x7F & rtccal;
321 	}
322 
323 	return retval;
324 }
325 
ab8500_sysfs_store_rtc_calibration(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)326 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
327 				struct device_attribute *attr,
328 				const char *buf, size_t count)
329 {
330 	int retval;
331 	int calibration = 0;
332 
333 	if (sscanf(buf, " %i ", &calibration) != 1) {
334 		dev_err(dev, "Failed to store RTC calibration attribute\n");
335 		return -EINVAL;
336 	}
337 
338 	retval = ab8500_rtc_set_calibration(dev, calibration);
339 
340 	return retval ? retval : count;
341 }
342 
ab8500_sysfs_show_rtc_calibration(struct device * dev,struct device_attribute * attr,char * buf)343 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
344 				struct device_attribute *attr, char *buf)
345 {
346 	int  retval = 0;
347 	int  calibration = 0;
348 
349 	retval = ab8500_rtc_get_calibration(dev, &calibration);
350 	if (retval < 0) {
351 		dev_err(dev, "Failed to read RTC calibration attribute\n");
352 		sprintf(buf, "0\n");
353 		return retval;
354 	}
355 
356 	return sprintf(buf, "%d\n", calibration);
357 }
358 
359 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
360 		   ab8500_sysfs_show_rtc_calibration,
361 		   ab8500_sysfs_store_rtc_calibration);
362 
ab8500_sysfs_rtc_register(struct device * dev)363 static int ab8500_sysfs_rtc_register(struct device *dev)
364 {
365 	return device_create_file(dev, &dev_attr_rtc_calibration);
366 }
367 
ab8500_sysfs_rtc_unregister(struct device * dev)368 static void ab8500_sysfs_rtc_unregister(struct device *dev)
369 {
370 	device_remove_file(dev, &dev_attr_rtc_calibration);
371 }
372 
rtc_alarm_handler(int irq,void * data)373 static irqreturn_t rtc_alarm_handler(int irq, void *data)
374 {
375 	struct rtc_device *rtc = data;
376 	unsigned long events = RTC_IRQF | RTC_AF;
377 
378 	dev_dbg(&rtc->dev, "%s\n", __func__);
379 	rtc_update_irq(rtc, 1, events);
380 
381 	return IRQ_HANDLED;
382 }
383 
384 static const struct rtc_class_ops ab8500_rtc_ops = {
385 	.read_time		= ab8500_rtc_read_time,
386 	.set_time		= ab8500_rtc_set_time,
387 	.read_alarm		= ab8500_rtc_read_alarm,
388 	.set_alarm		= ab8500_rtc_set_alarm,
389 	.alarm_irq_enable	= ab8500_rtc_irq_enable,
390 };
391 
392 static const struct platform_device_id ab85xx_rtc_ids[] = {
393 	{ "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
394 	{ /* sentinel */ }
395 };
396 MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
397 
ab8500_rtc_probe(struct platform_device * pdev)398 static int ab8500_rtc_probe(struct platform_device *pdev)
399 {
400 	const struct platform_device_id *platid = platform_get_device_id(pdev);
401 	int err;
402 	struct rtc_device *rtc;
403 	u8 rtc_ctrl;
404 	int irq;
405 
406 	irq = platform_get_irq_byname(pdev, "ALARM");
407 	if (irq < 0)
408 		return irq;
409 
410 	/* For RTC supply test */
411 	err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
412 		AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
413 	if (err < 0)
414 		return err;
415 
416 	/* Wait for reset by the PorRtc */
417 	usleep_range(1000, 5000);
418 
419 	err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
420 		AB8500_RTC_STAT_REG, &rtc_ctrl);
421 	if (err < 0)
422 		return err;
423 
424 	/* Check if the RTC Supply fails */
425 	if (!(rtc_ctrl & RTC_STATUS_DATA)) {
426 		dev_err(&pdev->dev, "RTC supply failure\n");
427 		return -ENODEV;
428 	}
429 
430 	device_init_wakeup(&pdev->dev, true);
431 
432 	rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
433 				(struct rtc_class_ops *)platid->driver_data,
434 				THIS_MODULE);
435 	if (IS_ERR(rtc)) {
436 		dev_err(&pdev->dev, "Registration failed\n");
437 		err = PTR_ERR(rtc);
438 		return err;
439 	}
440 
441 	err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
442 			rtc_alarm_handler, IRQF_ONESHOT,
443 			"ab8500-rtc", rtc);
444 	if (err < 0)
445 		return err;
446 
447 	dev_pm_set_wake_irq(&pdev->dev, irq);
448 	platform_set_drvdata(pdev, rtc);
449 
450 	err = ab8500_sysfs_rtc_register(&pdev->dev);
451 	if (err) {
452 		dev_err(&pdev->dev, "sysfs RTC failed to register\n");
453 		return err;
454 	}
455 
456 	rtc->uie_unsupported = 1;
457 
458 	return 0;
459 }
460 
ab8500_rtc_remove(struct platform_device * pdev)461 static int ab8500_rtc_remove(struct platform_device *pdev)
462 {
463 	dev_pm_clear_wake_irq(&pdev->dev);
464 	device_init_wakeup(&pdev->dev, false);
465 	ab8500_sysfs_rtc_unregister(&pdev->dev);
466 
467 	return 0;
468 }
469 
470 static struct platform_driver ab8500_rtc_driver = {
471 	.driver = {
472 		.name = "ab8500-rtc",
473 	},
474 	.probe	= ab8500_rtc_probe,
475 	.remove = ab8500_rtc_remove,
476 	.id_table = ab85xx_rtc_ids,
477 };
478 
479 module_platform_driver(ab8500_rtc_driver);
480 
481 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
482 MODULE_DESCRIPTION("AB8500 RTC Driver");
483 MODULE_LICENSE("GPL v2");
484