1/*
2 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
3 *
4 * Based on code by Randy Vinson <rvinson@mvista.com>,
5 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
6 *
7 * Copyright (C) 2014 Rose Technology
8 * Copyright (C) 2006-2007 Freescale Semiconductor
9 *
10 * 2005 (c) MontaVista Software, Inc. This file is licensed under
11 * the terms of the GNU General Public License version 2. This program
12 * is licensed "as is" without any warranty of any kind, whether express
13 * or implied.
14 */
15/*
16 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
17 * recommened in .../Documentation/i2c/writing-clients section
18 * "Sending and receiving", using SMBus level communication is preferred.
19 */
20
21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/interrupt.h>
26#include <linux/i2c.h>
27#include <linux/rtc.h>
28#include <linux/bcd.h>
29#include <linux/workqueue.h>
30#include <linux/slab.h>
31#include <linux/pm.h>
32#ifdef CONFIG_RTC_DRV_DS1374_WDT
33#include <linux/fs.h>
34#include <linux/ioctl.h>
35#include <linux/miscdevice.h>
36#include <linux/reboot.h>
37#include <linux/watchdog.h>
38#endif
39
40#define DS1374_REG_TOD0		0x00 /* Time of Day */
41#define DS1374_REG_TOD1		0x01
42#define DS1374_REG_TOD2		0x02
43#define DS1374_REG_TOD3		0x03
44#define DS1374_REG_WDALM0	0x04 /* Watchdog/Alarm */
45#define DS1374_REG_WDALM1	0x05
46#define DS1374_REG_WDALM2	0x06
47#define DS1374_REG_CR		0x07 /* Control */
48#define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
49#define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
50#define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
51#define DS1374_REG_SR		0x08 /* Status */
52#define DS1374_REG_SR_OSF	0x80 /* Oscillator Stop Flag */
53#define DS1374_REG_SR_AF	0x01 /* Alarm Flag */
54#define DS1374_REG_TCR		0x09 /* Trickle Charge */
55
56static const struct i2c_device_id ds1374_id[] = {
57	{ "ds1374", 0 },
58	{ }
59};
60MODULE_DEVICE_TABLE(i2c, ds1374_id);
61
62#ifdef CONFIG_OF
63static const struct of_device_id ds1374_of_match[] = {
64	{ .compatible = "dallas,ds1374" },
65	{ }
66};
67MODULE_DEVICE_TABLE(of, ds1374_of_match);
68#endif
69
70struct ds1374 {
71	struct i2c_client *client;
72	struct rtc_device *rtc;
73	struct work_struct work;
74
75	/* The mutex protects alarm operations, and prevents a race
76	 * between the enable_irq() in the workqueue and the free_irq()
77	 * in the remove function.
78	 */
79	struct mutex mutex;
80	int exiting;
81};
82
83static struct i2c_driver ds1374_driver;
84
85static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
86			   int reg, int nbytes)
87{
88	u8 buf[4];
89	int ret;
90	int i;
91
92	if (nbytes > 4) {
93		WARN_ON(1);
94		return -EINVAL;
95	}
96
97	ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
98
99	if (ret < 0)
100		return ret;
101	if (ret < nbytes)
102		return -EIO;
103
104	for (i = nbytes - 1, *time = 0; i >= 0; i--)
105		*time = (*time << 8) | buf[i];
106
107	return 0;
108}
109
110static int ds1374_write_rtc(struct i2c_client *client, u32 time,
111			    int reg, int nbytes)
112{
113	u8 buf[4];
114	int i;
115
116	if (nbytes > 4) {
117		WARN_ON(1);
118		return -EINVAL;
119	}
120
121	for (i = 0; i < nbytes; i++) {
122		buf[i] = time & 0xff;
123		time >>= 8;
124	}
125
126	return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
127}
128
129static int ds1374_check_rtc_status(struct i2c_client *client)
130{
131	int ret = 0;
132	int control, stat;
133
134	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
135	if (stat < 0)
136		return stat;
137
138	if (stat & DS1374_REG_SR_OSF)
139		dev_warn(&client->dev,
140			 "oscillator discontinuity flagged, time unreliable\n");
141
142	stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
143
144	ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
145	if (ret < 0)
146		return ret;
147
148	/* If the alarm is pending, clear it before requesting
149	 * the interrupt, so an interrupt event isn't reported
150	 * before everything is initialized.
151	 */
152
153	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
154	if (control < 0)
155		return control;
156
157	control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
158	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
159}
160
161static int ds1374_read_time(struct device *dev, struct rtc_time *time)
162{
163	struct i2c_client *client = to_i2c_client(dev);
164	u32 itime;
165	int ret;
166
167	ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
168	if (!ret)
169		rtc_time_to_tm(itime, time);
170
171	return ret;
172}
173
174static int ds1374_set_time(struct device *dev, struct rtc_time *time)
175{
176	struct i2c_client *client = to_i2c_client(dev);
177	unsigned long itime;
178
179	rtc_tm_to_time(time, &itime);
180	return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
181}
182
183#ifndef CONFIG_RTC_DRV_DS1374_WDT
184/* The ds1374 has a decrementer for an alarm, rather than a comparator.
185 * If the time of day is changed, then the alarm will need to be
186 * reset.
187 */
188static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
189{
190	struct i2c_client *client = to_i2c_client(dev);
191	struct ds1374 *ds1374 = i2c_get_clientdata(client);
192	u32 now, cur_alarm;
193	int cr, sr;
194	int ret = 0;
195
196	if (client->irq <= 0)
197		return -EINVAL;
198
199	mutex_lock(&ds1374->mutex);
200
201	cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
202	if (ret < 0)
203		goto out;
204
205	sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
206	if (ret < 0)
207		goto out;
208
209	ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
210	if (ret)
211		goto out;
212
213	ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
214	if (ret)
215		goto out;
216
217	rtc_time_to_tm(now + cur_alarm, &alarm->time);
218	alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
219	alarm->pending = !!(sr & DS1374_REG_SR_AF);
220
221out:
222	mutex_unlock(&ds1374->mutex);
223	return ret;
224}
225
226static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
227{
228	struct i2c_client *client = to_i2c_client(dev);
229	struct ds1374 *ds1374 = i2c_get_clientdata(client);
230	struct rtc_time now;
231	unsigned long new_alarm, itime;
232	int cr;
233	int ret = 0;
234
235	if (client->irq <= 0)
236		return -EINVAL;
237
238	ret = ds1374_read_time(dev, &now);
239	if (ret < 0)
240		return ret;
241
242	rtc_tm_to_time(&alarm->time, &new_alarm);
243	rtc_tm_to_time(&now, &itime);
244
245	/* This can happen due to races, in addition to dates that are
246	 * truly in the past.  To avoid requiring the caller to check for
247	 * races, dates in the past are assumed to be in the recent past
248	 * (i.e. not something that we'd rather the caller know about via
249	 * an error), and the alarm is set to go off as soon as possible.
250	 */
251	if (time_before_eq(new_alarm, itime))
252		new_alarm = 1;
253	else
254		new_alarm -= itime;
255
256	mutex_lock(&ds1374->mutex);
257
258	ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
259	if (ret < 0)
260		goto out;
261
262	/* Disable any existing alarm before setting the new one
263	 * (or lack thereof). */
264	cr &= ~DS1374_REG_CR_WACE;
265
266	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
267	if (ret < 0)
268		goto out;
269
270	ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
271	if (ret)
272		goto out;
273
274	if (alarm->enabled) {
275		cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
276		cr &= ~DS1374_REG_CR_WDALM;
277
278		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
279	}
280
281out:
282	mutex_unlock(&ds1374->mutex);
283	return ret;
284}
285#endif
286
287static irqreturn_t ds1374_irq(int irq, void *dev_id)
288{
289	struct i2c_client *client = dev_id;
290	struct ds1374 *ds1374 = i2c_get_clientdata(client);
291
292	disable_irq_nosync(irq);
293	schedule_work(&ds1374->work);
294	return IRQ_HANDLED;
295}
296
297static void ds1374_work(struct work_struct *work)
298{
299	struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
300	struct i2c_client *client = ds1374->client;
301	int stat, control;
302
303	mutex_lock(&ds1374->mutex);
304
305	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
306	if (stat < 0)
307		goto unlock;
308
309	if (stat & DS1374_REG_SR_AF) {
310		stat &= ~DS1374_REG_SR_AF;
311		i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
312
313		control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
314		if (control < 0)
315			goto out;
316
317		control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
318		i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
319
320		rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
321	}
322
323out:
324	if (!ds1374->exiting)
325		enable_irq(client->irq);
326unlock:
327	mutex_unlock(&ds1374->mutex);
328}
329
330#ifndef CONFIG_RTC_DRV_DS1374_WDT
331static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
332{
333	struct i2c_client *client = to_i2c_client(dev);
334	struct ds1374 *ds1374 = i2c_get_clientdata(client);
335	int ret;
336
337	mutex_lock(&ds1374->mutex);
338
339	ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
340	if (ret < 0)
341		goto out;
342
343	if (enabled) {
344		ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
345		ret &= ~DS1374_REG_CR_WDALM;
346	} else {
347		ret &= ~DS1374_REG_CR_WACE;
348	}
349	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
350
351out:
352	mutex_unlock(&ds1374->mutex);
353	return ret;
354}
355#endif
356
357static const struct rtc_class_ops ds1374_rtc_ops = {
358	.read_time = ds1374_read_time,
359	.set_time = ds1374_set_time,
360#ifndef CONFIG_RTC_DRV_DS1374_WDT
361	.read_alarm = ds1374_read_alarm,
362	.set_alarm = ds1374_set_alarm,
363	.alarm_irq_enable = ds1374_alarm_irq_enable,
364#endif
365};
366
367#ifdef CONFIG_RTC_DRV_DS1374_WDT
368/*
369 *****************************************************************************
370 *
371 * Watchdog Driver
372 *
373 *****************************************************************************
374 */
375static struct i2c_client *save_client;
376/* Default margin */
377#define WD_TIMO 131762
378
379#define DRV_NAME "DS1374 Watchdog"
380
381static int wdt_margin = WD_TIMO;
382static unsigned long wdt_is_open;
383module_param(wdt_margin, int, 0);
384MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
385
386static const struct watchdog_info ds1374_wdt_info = {
387	.identity       = "DS1374 WTD",
388	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
389						WDIOF_MAGICCLOSE,
390};
391
392static int ds1374_wdt_settimeout(unsigned int timeout)
393{
394	int ret = -ENOIOCTLCMD;
395	int cr;
396
397	ret = cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
398	if (ret < 0)
399		goto out;
400
401	/* Disable any existing watchdog/alarm before setting the new one */
402	cr &= ~DS1374_REG_CR_WACE;
403
404	ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
405	if (ret < 0)
406		goto out;
407
408	/* Set new watchdog time */
409	ret = ds1374_write_rtc(save_client, timeout, DS1374_REG_WDALM0, 3);
410	if (ret) {
411		pr_info("couldn't set new watchdog time\n");
412		goto out;
413	}
414
415	/* Enable watchdog timer */
416	cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
417	cr &= ~DS1374_REG_CR_AIE;
418
419	ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
420	if (ret < 0)
421		goto out;
422
423	return 0;
424out:
425	return ret;
426}
427
428
429/*
430 * Reload the watchdog timer.  (ie, pat the watchdog)
431 */
432static void ds1374_wdt_ping(void)
433{
434	u32 val;
435	int ret = 0;
436
437	ret = ds1374_read_rtc(save_client, &val, DS1374_REG_WDALM0, 3);
438	if (ret)
439		pr_info("WD TICK FAIL!!!!!!!!!! %i\n", ret);
440}
441
442static void ds1374_wdt_disable(void)
443{
444	int ret = -ENOIOCTLCMD;
445	int cr;
446
447	cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
448	/* Disable watchdog timer */
449	cr &= ~DS1374_REG_CR_WACE;
450
451	ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
452}
453
454/*
455 * Watchdog device is opened, and watchdog starts running.
456 */
457static int ds1374_wdt_open(struct inode *inode, struct file *file)
458{
459	struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
460
461	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
462		mutex_lock(&ds1374->mutex);
463		if (test_and_set_bit(0, &wdt_is_open)) {
464			mutex_unlock(&ds1374->mutex);
465			return -EBUSY;
466		}
467		/*
468		 *      Activate
469		 */
470		wdt_is_open = 1;
471		mutex_unlock(&ds1374->mutex);
472		return nonseekable_open(inode, file);
473	}
474	return -ENODEV;
475}
476
477/*
478 * Close the watchdog device.
479 */
480static int ds1374_wdt_release(struct inode *inode, struct file *file)
481{
482	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
483		clear_bit(0, &wdt_is_open);
484
485	return 0;
486}
487
488/*
489 * Pat the watchdog whenever device is written to.
490 */
491static ssize_t ds1374_wdt_write(struct file *file, const char __user *data,
492				size_t len, loff_t *ppos)
493{
494	if (len) {
495		ds1374_wdt_ping();
496		return 1;
497	}
498	return 0;
499}
500
501static ssize_t ds1374_wdt_read(struct file *file, char __user *data,
502				size_t len, loff_t *ppos)
503{
504	return 0;
505}
506
507/*
508 * Handle commands from user-space.
509 */
510static long ds1374_wdt_ioctl(struct file *file, unsigned int cmd,
511							unsigned long arg)
512{
513	int new_margin, options;
514
515	switch (cmd) {
516	case WDIOC_GETSUPPORT:
517		return copy_to_user((struct watchdog_info __user *)arg,
518		&ds1374_wdt_info, sizeof(ds1374_wdt_info)) ? -EFAULT : 0;
519
520	case WDIOC_GETSTATUS:
521	case WDIOC_GETBOOTSTATUS:
522		return put_user(0, (int __user *)arg);
523	case WDIOC_KEEPALIVE:
524		ds1374_wdt_ping();
525		return 0;
526	case WDIOC_SETTIMEOUT:
527		if (get_user(new_margin, (int __user *)arg))
528			return -EFAULT;
529
530		if (new_margin < 1 || new_margin > 16777216)
531			return -EINVAL;
532
533		wdt_margin = new_margin;
534		ds1374_wdt_settimeout(new_margin);
535		ds1374_wdt_ping();
536		/* fallthrough */
537	case WDIOC_GETTIMEOUT:
538		return put_user(wdt_margin, (int __user *)arg);
539	case WDIOC_SETOPTIONS:
540		if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
541			return -EFAULT;
542
543		if (options & WDIOS_DISABLECARD) {
544			pr_info("disable watchdog\n");
545			ds1374_wdt_disable();
546		}
547
548		if (options & WDIOS_ENABLECARD) {
549			pr_info("enable watchdog\n");
550			ds1374_wdt_settimeout(wdt_margin);
551			ds1374_wdt_ping();
552		}
553
554		return -EINVAL;
555	}
556	return -ENOTTY;
557}
558
559static long ds1374_wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
560			unsigned long arg)
561{
562	int ret;
563	struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
564
565	mutex_lock(&ds1374->mutex);
566	ret = ds1374_wdt_ioctl(file, cmd, arg);
567	mutex_unlock(&ds1374->mutex);
568
569	return ret;
570}
571
572static int ds1374_wdt_notify_sys(struct notifier_block *this,
573			unsigned long code, void *unused)
574{
575	if (code == SYS_DOWN || code == SYS_HALT)
576		/* Disable Watchdog */
577		ds1374_wdt_disable();
578	return NOTIFY_DONE;
579}
580
581static const struct file_operations ds1374_wdt_fops = {
582	.owner			= THIS_MODULE,
583	.read			= ds1374_wdt_read,
584	.unlocked_ioctl		= ds1374_wdt_unlocked_ioctl,
585	.write			= ds1374_wdt_write,
586	.open                   = ds1374_wdt_open,
587	.release                = ds1374_wdt_release,
588	.llseek			= no_llseek,
589};
590
591static struct miscdevice ds1374_miscdev = {
592	.minor          = WATCHDOG_MINOR,
593	.name           = "watchdog",
594	.fops           = &ds1374_wdt_fops,
595};
596
597static struct notifier_block ds1374_wdt_notifier = {
598	.notifier_call = ds1374_wdt_notify_sys,
599};
600
601#endif /*CONFIG_RTC_DRV_DS1374_WDT*/
602/*
603 *****************************************************************************
604 *
605 *	Driver Interface
606 *
607 *****************************************************************************
608 */
609static int ds1374_probe(struct i2c_client *client,
610			const struct i2c_device_id *id)
611{
612	struct ds1374 *ds1374;
613	int ret;
614
615	ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
616	if (!ds1374)
617		return -ENOMEM;
618
619	ds1374->client = client;
620	i2c_set_clientdata(client, ds1374);
621
622	INIT_WORK(&ds1374->work, ds1374_work);
623	mutex_init(&ds1374->mutex);
624
625	ret = ds1374_check_rtc_status(client);
626	if (ret)
627		return ret;
628
629	if (client->irq > 0) {
630		ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
631					"ds1374", client);
632		if (ret) {
633			dev_err(&client->dev, "unable to request IRQ\n");
634			return ret;
635		}
636
637		device_set_wakeup_capable(&client->dev, 1);
638	}
639
640	ds1374->rtc = devm_rtc_device_register(&client->dev, client->name,
641						&ds1374_rtc_ops, THIS_MODULE);
642	if (IS_ERR(ds1374->rtc)) {
643		dev_err(&client->dev, "unable to register the class device\n");
644		return PTR_ERR(ds1374->rtc);
645	}
646
647#ifdef CONFIG_RTC_DRV_DS1374_WDT
648	save_client = client;
649	ret = misc_register(&ds1374_miscdev);
650	if (ret)
651		return ret;
652	ret = register_reboot_notifier(&ds1374_wdt_notifier);
653	if (ret) {
654		misc_deregister(&ds1374_miscdev);
655		return ret;
656	}
657	ds1374_wdt_settimeout(131072);
658#endif
659
660	return 0;
661}
662
663static int ds1374_remove(struct i2c_client *client)
664{
665	struct ds1374 *ds1374 = i2c_get_clientdata(client);
666#ifdef CONFIG_RTC_DRV_DS1374_WDT
667	misc_deregister(&ds1374_miscdev);
668	ds1374_miscdev.parent = NULL;
669	unregister_reboot_notifier(&ds1374_wdt_notifier);
670#endif
671
672	if (client->irq > 0) {
673		mutex_lock(&ds1374->mutex);
674		ds1374->exiting = 1;
675		mutex_unlock(&ds1374->mutex);
676
677		devm_free_irq(&client->dev, client->irq, client);
678		cancel_work_sync(&ds1374->work);
679	}
680
681	return 0;
682}
683
684#ifdef CONFIG_PM_SLEEP
685static int ds1374_suspend(struct device *dev)
686{
687	struct i2c_client *client = to_i2c_client(dev);
688
689	if (client->irq > 0 && device_may_wakeup(&client->dev))
690		enable_irq_wake(client->irq);
691	return 0;
692}
693
694static int ds1374_resume(struct device *dev)
695{
696	struct i2c_client *client = to_i2c_client(dev);
697
698	if (client->irq > 0 && device_may_wakeup(&client->dev))
699		disable_irq_wake(client->irq);
700	return 0;
701}
702#endif
703
704static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
705
706static struct i2c_driver ds1374_driver = {
707	.driver = {
708		.name = "rtc-ds1374",
709		.pm = &ds1374_pm,
710	},
711	.probe = ds1374_probe,
712	.remove = ds1374_remove,
713	.id_table = ds1374_id,
714};
715
716module_i2c_driver(ds1374_driver);
717
718MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
719MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
720MODULE_LICENSE("GPL");
721