Free Electrons

Embedded Linux Experts

  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
/*
 * Copyright (C) ST-Ericsson SA 2010
 *
 * License terms: GNU General Public License (GPL) version 2
 * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
 *
 * RTC clock driver for the RTC part of the AB8500 Power management chip.
 * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
 * Linus Walleij <linus.walleij@stericsson.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/pm_wakeirq.h>

#define AB8500_RTC_SOFF_STAT_REG	0x00
#define AB8500_RTC_CC_CONF_REG		0x01
#define AB8500_RTC_READ_REQ_REG		0x02
#define AB8500_RTC_WATCH_TSECMID_REG	0x03
#define AB8500_RTC_WATCH_TSECHI_REG	0x04
#define AB8500_RTC_WATCH_TMIN_LOW_REG	0x05
#define AB8500_RTC_WATCH_TMIN_MID_REG	0x06
#define AB8500_RTC_WATCH_TMIN_HI_REG	0x07
#define AB8500_RTC_ALRM_MIN_LOW_REG	0x08
#define AB8500_RTC_ALRM_MIN_MID_REG	0x09
#define AB8500_RTC_ALRM_MIN_HI_REG	0x0A
#define AB8500_RTC_STAT_REG		0x0B
#define AB8500_RTC_BKUP_CHG_REG		0x0C
#define AB8500_RTC_FORCE_BKUP_REG	0x0D
#define AB8500_RTC_CALIB_REG		0x0E
#define AB8500_RTC_SWITCH_STAT_REG	0x0F
#define AB8540_RTC_ALRM_SEC		0x22
#define AB8540_RTC_ALRM_MIN_LOW_REG	0x23
#define AB8540_RTC_ALRM_MIN_MID_REG	0x24
#define AB8540_RTC_ALRM_MIN_HI_REG	0x25

/* RtcReadRequest bits */
#define RTC_READ_REQUEST		0x01
#define RTC_WRITE_REQUEST		0x02

/* RtcCtrl bits */
#define RTC_ALARM_ENA			0x04
#define RTC_STATUS_DATA			0x01

#define COUNTS_PER_SEC			(0xF000 / 60)
#define AB8500_RTC_EPOCH		2000

static const u8 ab8500_rtc_time_regs[] = {
	AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
	AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
	AB8500_RTC_WATCH_TSECMID_REG
};

static const u8 ab8500_rtc_alarm_regs[] = {
	AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
	AB8500_RTC_ALRM_MIN_LOW_REG
};

static const u8 ab8540_rtc_alarm_regs[] = {
	AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
	AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
};

/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
static unsigned long get_elapsed_seconds(int year)
{
	unsigned long secs;
	struct rtc_time tm = {
		.tm_year = year - 1900,
		.tm_mday = 1,
	};

	/*
	 * This function calculates secs from 1970 and not from
	 * 1900, even if we supply the offset from year 1900.
	 */
	rtc_tm_to_time(&tm, &secs);
	return secs;
}

static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	unsigned long timeout = jiffies + HZ;
	int retval, i;
	unsigned long mins, secs;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
	u8 value;

	/* Request a data read */
	retval = abx500_set_register_interruptible(dev,
		AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
	if (retval < 0)
		return retval;

	/* Wait for some cycles after enabling the rtc read in ab8500 */
	while (time_before(jiffies, timeout)) {
		retval = abx500_get_register_interruptible(dev,
			AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
		if (retval < 0)
			return retval;

		if (!(value & RTC_READ_REQUEST))
			break;

		usleep_range(1000, 5000);
	}

	/* Read the Watchtime registers */
	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
		retval = abx500_get_register_interruptible(dev,
			AB8500_RTC, ab8500_rtc_time_regs[i], &value);
		if (retval < 0)
			return retval;
		buf[i] = value;
	}

	mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];

	secs =	(buf[3] << 8) | buf[4];
	secs =	secs / COUNTS_PER_SEC;
	secs =	secs + (mins * 60);

	/* Add back the initially subtracted number of seconds */
	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

	rtc_time_to_tm(secs, tm);
	return rtc_valid_tm(tm);
}

static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
	unsigned long no_secs, no_mins, secs = 0;

	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
		dev_dbg(dev, "year should be equal to or greater than %d\n",
				AB8500_RTC_EPOCH);
		return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(tm, &secs);

	/*
	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
	 * we only have a small counter in the RTC.
	 */
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

	no_mins = secs / 60;

	no_secs = secs % 60;
	/* Make the seconds count as per the RTC resolution */
	no_secs = no_secs * COUNTS_PER_SEC;

	buf[4] = no_secs & 0xFF;
	buf[3] = (no_secs >> 8) & 0xFF;

	buf[2] = no_mins & 0xFF;
	buf[1] = (no_mins >> 8) & 0xFF;
	buf[0] = (no_mins >> 16) & 0xFF;

	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
			ab8500_rtc_time_regs[i], buf[i]);
		if (retval < 0)
			return retval;
	}

	/* Request a data write */
	return abx500_set_register_interruptible(dev, AB8500_RTC,
		AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
}

static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	int retval, i;
	u8 rtc_ctrl, value;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
	unsigned long secs, mins;

	/* Check if the alarm is enabled or not */
	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
		AB8500_RTC_STAT_REG, &rtc_ctrl);
	if (retval < 0)
		return retval;

	if (rtc_ctrl & RTC_ALARM_ENA)
		alarm->enabled = 1;
	else
		alarm->enabled = 0;

	alarm->pending = 0;

	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
		retval = abx500_get_register_interruptible(dev, AB8500_RTC,
			ab8500_rtc_alarm_regs[i], &value);
		if (retval < 0)
			return retval;
		buf[i] = value;
	}

	mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
	secs = mins * 60;

	/* Add back the initially subtracted number of seconds */
	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

	rtc_time_to_tm(secs, &alarm->time);

	return rtc_valid_tm(&alarm->time);
}

static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
	return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
		AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
		enabled ? RTC_ALARM_ENA : 0);
}

static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
	unsigned long mins, secs = 0, cursec = 0;
	struct rtc_time curtm;

	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
		dev_dbg(dev, "year should be equal to or greater than %d\n",
				AB8500_RTC_EPOCH);
		return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(&alarm->time, &secs);

	/*
	 * Check whether alarm is set less than 1min.
	 * Since our RTC doesn't support alarm resolution less than 1min,
	 * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
	 */
	ab8500_rtc_read_time(dev, &curtm); /* Read current time */
	rtc_tm_to_time(&curtm, &cursec);
	if ((secs - cursec) < 59) {
		dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
		return -EINVAL;
	}

	/*
	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
	 * we only have a small counter in the RTC.
	 */
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

	mins = secs / 60;

	buf[2] = mins & 0xFF;
	buf[1] = (mins >> 8) & 0xFF;
	buf[0] = (mins >> 16) & 0xFF;

	/* Set the alarm time */
	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
			ab8500_rtc_alarm_regs[i], buf[i]);
		if (retval < 0)
			return retval;
	}

	return ab8500_rtc_irq_enable(dev, alarm->enabled);
}

static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
	unsigned long mins, secs = 0;

	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
		dev_dbg(dev, "year should be equal to or greater than %d\n",
				AB8500_RTC_EPOCH);
		return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(&alarm->time, &secs);

	/*
	 * Convert it to the number of seconds since 01-01-2000 00:00:00
	 */
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
	mins = secs / 60;

	buf[3] = secs % 60;
	buf[2] = mins & 0xFF;
	buf[1] = (mins >> 8) & 0xFF;
	buf[0] = (mins >> 16) & 0xFF;

	/* Set the alarm time */
	for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
			ab8540_rtc_alarm_regs[i], buf[i]);
		if (retval < 0)
			return retval;
	}

	return ab8500_rtc_irq_enable(dev, alarm->enabled);
}

static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
{
	int retval;
	u8  rtccal = 0;

	/*
	 * Check that the calibration value (which is in units of 0.5
	 * parts-per-million) is in the AB8500's range for RtcCalibration
	 * register. -128 (0x80) is not permitted because the AB8500 uses
	 * a sign-bit rather than two's complement, so 0x80 is just another
	 * representation of zero.
	 */
	if ((calibration < -127) || (calibration > 127)) {
		dev_err(dev, "RtcCalibration value outside permitted range\n");
		return -EINVAL;
	}

	/*
	 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
	 * so need to convert to this sort of representation before writing
	 * into RtcCalibration register...
	 */
	if (calibration >= 0)
		rtccal = 0x7F & calibration;
	else
		rtccal = ~(calibration - 1) | 0x80;

	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
			AB8500_RTC_CALIB_REG, rtccal);

	return retval;
}

static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
{
	int retval;
	u8  rtccal = 0;

	retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
			AB8500_RTC_CALIB_REG, &rtccal);
	if (retval >= 0) {
		/*
		 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
		 * so need to convert value from RtcCalibration register into
		 * a two's complement signed value...
		 */
		if (rtccal & 0x80)
			*calibration = 0 - (rtccal & 0x7F);
		else
			*calibration = 0x7F & rtccal;
	}

	return retval;
}

static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	int retval;
	int calibration = 0;

	if (sscanf(buf, " %i ", &calibration) != 1) {
		dev_err(dev, "Failed to store RTC calibration attribute\n");
		return -EINVAL;
	}

	retval = ab8500_rtc_set_calibration(dev, calibration);

	return retval ? retval : count;
}

static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	int  retval = 0;
	int  calibration = 0;

	retval = ab8500_rtc_get_calibration(dev, &calibration);
	if (retval < 0) {
		dev_err(dev, "Failed to read RTC calibration attribute\n");
		sprintf(buf, "0\n");
		return retval;
	}

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

static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
		   ab8500_sysfs_show_rtc_calibration,
		   ab8500_sysfs_store_rtc_calibration);

static int ab8500_sysfs_rtc_register(struct device *dev)
{
	return device_create_file(dev, &dev_attr_rtc_calibration);
}

static void ab8500_sysfs_rtc_unregister(struct device *dev)
{
	device_remove_file(dev, &dev_attr_rtc_calibration);
}

static irqreturn_t rtc_alarm_handler(int irq, void *data)
{
	struct rtc_device *rtc = data;
	unsigned long events = RTC_IRQF | RTC_AF;

	dev_dbg(&rtc->dev, "%s\n", __func__);
	rtc_update_irq(rtc, 1, events);

	return IRQ_HANDLED;
}

static const struct rtc_class_ops ab8500_rtc_ops = {
	.read_time		= ab8500_rtc_read_time,
	.set_time		= ab8500_rtc_set_time,
	.read_alarm		= ab8500_rtc_read_alarm,
	.set_alarm		= ab8500_rtc_set_alarm,
	.alarm_irq_enable	= ab8500_rtc_irq_enable,
};

static const struct rtc_class_ops ab8540_rtc_ops = {
	.read_time		= ab8500_rtc_read_time,
	.set_time		= ab8500_rtc_set_time,
	.read_alarm		= ab8500_rtc_read_alarm,
	.set_alarm		= ab8540_rtc_set_alarm,
	.alarm_irq_enable	= ab8500_rtc_irq_enable,
};

static const struct platform_device_id ab85xx_rtc_ids[] = {
	{ "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
	{ "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);

static int ab8500_rtc_probe(struct platform_device *pdev)
{
	const struct platform_device_id *platid = platform_get_device_id(pdev);
	int err;
	struct rtc_device *rtc;
	u8 rtc_ctrl;
	int irq;

	irq = platform_get_irq_byname(pdev, "ALARM");
	if (irq < 0)
		return irq;

	/* For RTC supply test */
	err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
		AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
	if (err < 0)
		return err;

	/* Wait for reset by the PorRtc */
	usleep_range(1000, 5000);

	err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
		AB8500_RTC_STAT_REG, &rtc_ctrl);
	if (err < 0)
		return err;

	/* Check if the RTC Supply fails */
	if (!(rtc_ctrl & RTC_STATUS_DATA)) {
		dev_err(&pdev->dev, "RTC supply failure\n");
		return -ENODEV;
	}

	device_init_wakeup(&pdev->dev, true);

	rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
				(struct rtc_class_ops *)platid->driver_data,
				THIS_MODULE);
	if (IS_ERR(rtc)) {
		dev_err(&pdev->dev, "Registration failed\n");
		err = PTR_ERR(rtc);
		return err;
	}

	err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
			rtc_alarm_handler, IRQF_ONESHOT,
			"ab8500-rtc", rtc);
	if (err < 0)
		return err;

	dev_pm_set_wake_irq(&pdev->dev, irq);
	platform_set_drvdata(pdev, rtc);

	err = ab8500_sysfs_rtc_register(&pdev->dev);
	if (err) {
		dev_err(&pdev->dev, "sysfs RTC failed to register\n");
		return err;
	}

	rtc->uie_unsupported = 1;

	return 0;
}

static int ab8500_rtc_remove(struct platform_device *pdev)
{
	dev_pm_clear_wake_irq(&pdev->dev);
	device_init_wakeup(&pdev->dev, false);
	ab8500_sysfs_rtc_unregister(&pdev->dev);

	return 0;
}

static struct platform_driver ab8500_rtc_driver = {
	.driver = {
		.name = "ab8500-rtc",
	},
	.probe	= ab8500_rtc_probe,
	.remove = ab8500_rtc_remove,
	.id_table = ab85xx_rtc_ids,
};

module_platform_driver(ab8500_rtc_driver);

MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
MODULE_DESCRIPTION("AB8500 RTC Driver");
MODULE_LICENSE("GPL v2");