xref: /openbmc/linux/drivers/rtc/rtc-ds1374.c (revision 1fa6ac37) 
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) 2006-2007 Freescale Semiconductor
8  *
9  * 2005 (c) MontaVista Software, Inc. This file is licensed under
10  * the terms of the GNU General Public License version 2. This program
11  * is licensed "as is" without any warranty of any kind, whether express
12  * or implied.
13  */
14 /*
15  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
16  * recommened in .../Documentation/i2c/writing-clients section
17  * "Sending and receiving", using SMBus level communication is preferred.
18  */
19 
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/interrupt.h>
23 #include <linux/i2c.h>
24 #include <linux/rtc.h>
25 #include <linux/bcd.h>
26 #include <linux/workqueue.h>
27 #include <linux/slab.h>
28 
29 #define DS1374_REG_TOD0		0x00 /* Time of Day */
30 #define DS1374_REG_TOD1		0x01
31 #define DS1374_REG_TOD2		0x02
32 #define DS1374_REG_TOD3		0x03
33 #define DS1374_REG_WDALM0	0x04 /* Watchdog/Alarm */
34 #define DS1374_REG_WDALM1	0x05
35 #define DS1374_REG_WDALM2	0x06
36 #define DS1374_REG_CR		0x07 /* Control */
37 #define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
38 #define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
39 #define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
40 #define DS1374_REG_SR		0x08 /* Status */
41 #define DS1374_REG_SR_OSF	0x80 /* Oscillator Stop Flag */
42 #define DS1374_REG_SR_AF	0x01 /* Alarm Flag */
43 #define DS1374_REG_TCR		0x09 /* Trickle Charge */
44 
45 static const struct i2c_device_id ds1374_id[] = {
46 	{ "ds1374", 0 },
47 	{ }
48 };
49 MODULE_DEVICE_TABLE(i2c, ds1374_id);
50 
51 struct ds1374 {
52 	struct i2c_client *client;
53 	struct rtc_device *rtc;
54 	struct work_struct work;
55 
56 	/* The mutex protects alarm operations, and prevents a race
57 	 * between the enable_irq() in the workqueue and the free_irq()
58 	 * in the remove function.
59 	 */
60 	struct mutex mutex;
61 	int exiting;
62 };
63 
64 static struct i2c_driver ds1374_driver;
65 
66 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
67                            int reg, int nbytes)
68 {
69 	u8 buf[4];
70 	int ret;
71 	int i;
72 
73 	if (nbytes > 4) {
74 		WARN_ON(1);
75 		return -EINVAL;
76 	}
77 
78 	ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
79 
80 	if (ret < 0)
81 		return ret;
82 	if (ret < nbytes)
83 		return -EIO;
84 
85 	for (i = nbytes - 1, *time = 0; i >= 0; i--)
86 		*time = (*time << 8) | buf[i];
87 
88 	return 0;
89 }
90 
91 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
92                             int reg, int nbytes)
93 {
94 	u8 buf[4];
95 	int i;
96 
97 	if (nbytes > 4) {
98 		WARN_ON(1);
99 		return -EINVAL;
100 	}
101 
102 	for (i = 0; i < nbytes; i++) {
103 		buf[i] = time & 0xff;
104 		time >>= 8;
105 	}
106 
107 	return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
108 }
109 
110 static int ds1374_check_rtc_status(struct i2c_client *client)
111 {
112 	int ret = 0;
113 	int control, stat;
114 
115 	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
116 	if (stat < 0)
117 		return stat;
118 
119 	if (stat & DS1374_REG_SR_OSF)
120 		dev_warn(&client->dev,
121 		         "oscillator discontinuity flagged, "
122 		         "time unreliable\n");
123 
124 	stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
125 
126 	ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
127 	if (ret < 0)
128 		return ret;
129 
130 	/* If the alarm is pending, clear it before requesting
131 	 * the interrupt, so an interrupt event isn't reported
132 	 * before everything is initialized.
133 	 */
134 
135 	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
136 	if (control < 0)
137 		return control;
138 
139 	control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
140 	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
141 }
142 
143 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
144 {
145 	struct i2c_client *client = to_i2c_client(dev);
146 	u32 itime;
147 	int ret;
148 
149 	ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
150 	if (!ret)
151 		rtc_time_to_tm(itime, time);
152 
153 	return ret;
154 }
155 
156 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
157 {
158 	struct i2c_client *client = to_i2c_client(dev);
159 	unsigned long itime;
160 
161 	rtc_tm_to_time(time, &itime);
162 	return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
163 }
164 
165 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
166  * If the time of day is changed, then the alarm will need to be
167  * reset.
168  */
169 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
170 {
171 	struct i2c_client *client = to_i2c_client(dev);
172 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
173 	u32 now, cur_alarm;
174 	int cr, sr;
175 	int ret = 0;
176 
177 	if (client->irq <= 0)
178 		return -EINVAL;
179 
180 	mutex_lock(&ds1374->mutex);
181 
182 	cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
183 	if (ret < 0)
184 		goto out;
185 
186 	sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
187 	if (ret < 0)
188 		goto out;
189 
190 	ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
191 	if (ret)
192 		goto out;
193 
194 	ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
195 	if (ret)
196 		goto out;
197 
198 	rtc_time_to_tm(now + cur_alarm, &alarm->time);
199 	alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
200 	alarm->pending = !!(sr & DS1374_REG_SR_AF);
201 
202 out:
203 	mutex_unlock(&ds1374->mutex);
204 	return ret;
205 }
206 
207 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
208 {
209 	struct i2c_client *client = to_i2c_client(dev);
210 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
211 	struct rtc_time now;
212 	unsigned long new_alarm, itime;
213 	int cr;
214 	int ret = 0;
215 
216 	if (client->irq <= 0)
217 		return -EINVAL;
218 
219 	ret = ds1374_read_time(dev, &now);
220 	if (ret < 0)
221 		return ret;
222 
223 	rtc_tm_to_time(&alarm->time, &new_alarm);
224 	rtc_tm_to_time(&now, &itime);
225 
226 	/* This can happen due to races, in addition to dates that are
227 	 * truly in the past.  To avoid requiring the caller to check for
228 	 * races, dates in the past are assumed to be in the recent past
229 	 * (i.e. not something that we'd rather the caller know about via
230 	 * an error), and the alarm is set to go off as soon as possible.
231 	 */
232 	if (time_before_eq(new_alarm, itime))
233 		new_alarm = 1;
234 	else
235 		new_alarm -= itime;
236 
237 	mutex_lock(&ds1374->mutex);
238 
239 	ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
240 	if (ret < 0)
241 		goto out;
242 
243 	/* Disable any existing alarm before setting the new one
244 	 * (or lack thereof). */
245 	cr &= ~DS1374_REG_CR_WACE;
246 
247 	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
248 	if (ret < 0)
249 		goto out;
250 
251 	ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
252 	if (ret)
253 		goto out;
254 
255 	if (alarm->enabled) {
256 		cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
257 		cr &= ~DS1374_REG_CR_WDALM;
258 
259 		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
260 	}
261 
262 out:
263 	mutex_unlock(&ds1374->mutex);
264 	return ret;
265 }
266 
267 static irqreturn_t ds1374_irq(int irq, void *dev_id)
268 {
269 	struct i2c_client *client = dev_id;
270 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
271 
272 	disable_irq_nosync(irq);
273 	schedule_work(&ds1374->work);
274 	return IRQ_HANDLED;
275 }
276 
277 static void ds1374_work(struct work_struct *work)
278 {
279 	struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
280 	struct i2c_client *client = ds1374->client;
281 	int stat, control;
282 
283 	mutex_lock(&ds1374->mutex);
284 
285 	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
286 	if (stat < 0)
287 		goto unlock;
288 
289 	if (stat & DS1374_REG_SR_AF) {
290 		stat &= ~DS1374_REG_SR_AF;
291 		i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
292 
293 		control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
294 		if (control < 0)
295 			goto out;
296 
297 		control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
298 		i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
299 
300 		rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
301 	}
302 
303 out:
304 	if (!ds1374->exiting)
305 		enable_irq(client->irq);
306 unlock:
307 	mutex_unlock(&ds1374->mutex);
308 }
309 
310 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
311 {
312 	struct i2c_client *client = to_i2c_client(dev);
313 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
314 	int ret = -ENOIOCTLCMD;
315 
316 	mutex_lock(&ds1374->mutex);
317 
318 	switch (cmd) {
319 	case RTC_AIE_OFF:
320 		ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
321 		if (ret < 0)
322 			goto out;
323 
324 		ret &= ~DS1374_REG_CR_WACE;
325 
326 		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
327 		if (ret < 0)
328 			goto out;
329 
330 		break;
331 
332 	case RTC_AIE_ON:
333 		ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
334 		if (ret < 0)
335 			goto out;
336 
337 		ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
338 		ret &= ~DS1374_REG_CR_WDALM;
339 
340 		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
341 		if (ret < 0)
342 			goto out;
343 
344 		break;
345 	}
346 
347 out:
348 	mutex_unlock(&ds1374->mutex);
349 	return ret;
350 }
351 
352 static const struct rtc_class_ops ds1374_rtc_ops = {
353 	.read_time = ds1374_read_time,
354 	.set_time = ds1374_set_time,
355 	.read_alarm = ds1374_read_alarm,
356 	.set_alarm = ds1374_set_alarm,
357 	.ioctl = ds1374_ioctl,
358 };
359 
360 static int ds1374_probe(struct i2c_client *client,
361 			const struct i2c_device_id *id)
362 {
363 	struct ds1374 *ds1374;
364 	int ret;
365 
366 	ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
367 	if (!ds1374)
368 		return -ENOMEM;
369 
370 	ds1374->client = client;
371 	i2c_set_clientdata(client, ds1374);
372 
373 	INIT_WORK(&ds1374->work, ds1374_work);
374 	mutex_init(&ds1374->mutex);
375 
376 	ret = ds1374_check_rtc_status(client);
377 	if (ret)
378 		goto out_free;
379 
380 	if (client->irq > 0) {
381 		ret = request_irq(client->irq, ds1374_irq, 0,
382 		                  "ds1374", client);
383 		if (ret) {
384 			dev_err(&client->dev, "unable to request IRQ\n");
385 			goto out_free;
386 		}
387 
388 		device_set_wakeup_capable(&client->dev, 1);
389 	}
390 
391 	ds1374->rtc = rtc_device_register(client->name, &client->dev,
392 	                                  &ds1374_rtc_ops, THIS_MODULE);
393 	if (IS_ERR(ds1374->rtc)) {
394 		ret = PTR_ERR(ds1374->rtc);
395 		dev_err(&client->dev, "unable to register the class device\n");
396 		goto out_irq;
397 	}
398 
399 	return 0;
400 
401 out_irq:
402 	if (client->irq > 0)
403 		free_irq(client->irq, client);
404 
405 out_free:
406 	kfree(ds1374);
407 	return ret;
408 }
409 
410 static int __devexit ds1374_remove(struct i2c_client *client)
411 {
412 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
413 
414 	if (client->irq > 0) {
415 		mutex_lock(&ds1374->mutex);
416 		ds1374->exiting = 1;
417 		mutex_unlock(&ds1374->mutex);
418 
419 		free_irq(client->irq, client);
420 		flush_scheduled_work();
421 	}
422 
423 	rtc_device_unregister(ds1374->rtc);
424 	kfree(ds1374);
425 	return 0;
426 }
427 
428 #ifdef CONFIG_PM
429 static int ds1374_suspend(struct i2c_client *client, pm_message_t state)
430 {
431 	if (client->irq >= 0 && device_may_wakeup(&client->dev))
432 		enable_irq_wake(client->irq);
433 	return 0;
434 }
435 
436 static int ds1374_resume(struct i2c_client *client)
437 {
438 	if (client->irq >= 0 && device_may_wakeup(&client->dev))
439 		disable_irq_wake(client->irq);
440 	return 0;
441 }
442 #else
443 #define ds1374_suspend	NULL
444 #define ds1374_resume	NULL
445 #endif
446 
447 static struct i2c_driver ds1374_driver = {
448 	.driver = {
449 		.name = "rtc-ds1374",
450 		.owner = THIS_MODULE,
451 	},
452 	.probe = ds1374_probe,
453 	.suspend = ds1374_suspend,
454 	.resume = ds1374_resume,
455 	.remove = __devexit_p(ds1374_remove),
456 	.id_table = ds1374_id,
457 };
458 
459 static int __init ds1374_init(void)
460 {
461 	return i2c_add_driver(&ds1374_driver);
462 }
463 
464 static void __exit ds1374_exit(void)
465 {
466 	i2c_del_driver(&ds1374_driver);
467 }
468 
469 module_init(ds1374_init);
470 module_exit(ds1374_exit);
471 
472 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
473 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
474 MODULE_LICENSE("GPL");
475