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
21 #define AB8500_RTC_SOFF_STAT_REG 0x00
22 #define AB8500_RTC_CC_CONF_REG 0x01
23 #define AB8500_RTC_READ_REQ_REG 0x02
24 #define AB8500_RTC_WATCH_TSECMID_REG 0x03
25 #define AB8500_RTC_WATCH_TSECHI_REG 0x04
26 #define AB8500_RTC_WATCH_TMIN_LOW_REG 0x05
27 #define AB8500_RTC_WATCH_TMIN_MID_REG 0x06
28 #define AB8500_RTC_WATCH_TMIN_HI_REG 0x07
29 #define AB8500_RTC_ALRM_MIN_LOW_REG 0x08
30 #define AB8500_RTC_ALRM_MIN_MID_REG 0x09
31 #define AB8500_RTC_ALRM_MIN_HI_REG 0x0A
32 #define AB8500_RTC_STAT_REG 0x0B
33 #define AB8500_RTC_BKUP_CHG_REG 0x0C
34 #define AB8500_RTC_FORCE_BKUP_REG 0x0D
35 #define AB8500_RTC_CALIB_REG 0x0E
36 #define AB8500_RTC_SWITCH_STAT_REG 0x0F
37
38 /* RtcReadRequest bits */
39 #define RTC_READ_REQUEST 0x01
40 #define RTC_WRITE_REQUEST 0x02
41
42 /* RtcCtrl bits */
43 #define RTC_ALARM_ENA 0x04
44 #define RTC_STATUS_DATA 0x01
45
46 #define COUNTS_PER_SEC (0xF000 / 60)
47 #define AB8500_RTC_EPOCH 2000
48
49 static const u8 ab8500_rtc_time_regs[] = {
50 AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
51 AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
52 AB8500_RTC_WATCH_TSECMID_REG
53 };
54
55 static const u8 ab8500_rtc_alarm_regs[] = {
56 AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
57 AB8500_RTC_ALRM_MIN_LOW_REG
58 };
59
60 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
get_elapsed_seconds(int year)61 static unsigned long get_elapsed_seconds(int year)
62 {
63 unsigned long secs;
64 struct rtc_time tm = {
65 .tm_year = year - 1900,
66 .tm_mday = 1,
67 };
68
69 /*
70 * This function calculates secs from 1970 and not from
71 * 1900, even if we supply the offset from year 1900.
72 */
73 rtc_tm_to_time(&tm, &secs);
74 return secs;
75 }
76
ab8500_rtc_read_time(struct device * dev,struct rtc_time * tm)77 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
78 {
79 unsigned long timeout = jiffies + HZ;
80 int retval, i;
81 unsigned long mins, secs;
82 unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
83 u8 value;
84
85 /* Request a data read */
86 retval = abx500_set_register_interruptible(dev,
87 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
88 if (retval < 0)
89 return retval;
90
91 /* Early AB8500 chips will not clear the rtc read request bit */
92 if (abx500_get_chip_id(dev) == 0) {
93 usleep_range(1000, 1000);
94 } else {
95 /* Wait for some cycles after enabling the rtc read in ab8500 */
96 while (time_before(jiffies, timeout)) {
97 retval = abx500_get_register_interruptible(dev,
98 AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
99 if (retval < 0)
100 return retval;
101
102 if (!(value & RTC_READ_REQUEST))
103 break;
104
105 usleep_range(1000, 5000);
106 }
107 }
108
109 /* Read the Watchtime registers */
110 for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
111 retval = abx500_get_register_interruptible(dev,
112 AB8500_RTC, ab8500_rtc_time_regs[i], &value);
113 if (retval < 0)
114 return retval;
115 buf[i] = value;
116 }
117
118 mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
119
120 secs = (buf[3] << 8) | buf[4];
121 secs = secs / COUNTS_PER_SEC;
122 secs = secs + (mins * 60);
123
124 /* Add back the initially subtracted number of seconds */
125 secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
126
127 rtc_time_to_tm(secs, tm);
128 return rtc_valid_tm(tm);
129 }
130
ab8500_rtc_set_time(struct device * dev,struct rtc_time * tm)131 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
132 {
133 int retval, i;
134 unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
135 unsigned long no_secs, no_mins, secs = 0;
136
137 if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
138 dev_dbg(dev, "year should be equal to or greater than %d\n",
139 AB8500_RTC_EPOCH);
140 return -EINVAL;
141 }
142
143 /* Get the number of seconds since 1970 */
144 rtc_tm_to_time(tm, &secs);
145
146 /*
147 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
148 * we only have a small counter in the RTC.
149 */
150 secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
151
152 no_mins = secs / 60;
153
154 no_secs = secs % 60;
155 /* Make the seconds count as per the RTC resolution */
156 no_secs = no_secs * COUNTS_PER_SEC;
157
158 buf[4] = no_secs & 0xFF;
159 buf[3] = (no_secs >> 8) & 0xFF;
160
161 buf[2] = no_mins & 0xFF;
162 buf[1] = (no_mins >> 8) & 0xFF;
163 buf[0] = (no_mins >> 16) & 0xFF;
164
165 for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
166 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
167 ab8500_rtc_time_regs[i], buf[i]);
168 if (retval < 0)
169 return retval;
170 }
171
172 /* Request a data write */
173 return abx500_set_register_interruptible(dev, AB8500_RTC,
174 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
175 }
176
ab8500_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)177 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
178 {
179 int retval, i;
180 u8 rtc_ctrl, value;
181 unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
182 unsigned long secs, mins;
183
184 /* Check if the alarm is enabled or not */
185 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
186 AB8500_RTC_STAT_REG, &rtc_ctrl);
187 if (retval < 0)
188 return retval;
189
190 if (rtc_ctrl & RTC_ALARM_ENA)
191 alarm->enabled = 1;
192 else
193 alarm->enabled = 0;
194
195 alarm->pending = 0;
196
197 for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
198 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
199 ab8500_rtc_alarm_regs[i], &value);
200 if (retval < 0)
201 return retval;
202 buf[i] = value;
203 }
204
205 mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
206 secs = mins * 60;
207
208 /* Add back the initially subtracted number of seconds */
209 secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
210
211 rtc_time_to_tm(secs, &alarm->time);
212
213 return rtc_valid_tm(&alarm->time);
214 }
215
ab8500_rtc_irq_enable(struct device * dev,unsigned int enabled)216 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
217 {
218 return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
219 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
220 enabled ? RTC_ALARM_ENA : 0);
221 }
222
ab8500_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)223 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
224 {
225 int retval, i;
226 unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
227 unsigned long mins, secs = 0;
228
229 if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
230 dev_dbg(dev, "year should be equal to or greater than %d\n",
231 AB8500_RTC_EPOCH);
232 return -EINVAL;
233 }
234
235 /* Get the number of seconds since 1970 */
236 rtc_tm_to_time(&alarm->time, &secs);
237
238 /*
239 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
240 * we only have a small counter in the RTC.
241 */
242 secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
243
244 mins = secs / 60;
245
246 buf[2] = mins & 0xFF;
247 buf[1] = (mins >> 8) & 0xFF;
248 buf[0] = (mins >> 16) & 0xFF;
249
250 /* Set the alarm time */
251 for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
252 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
253 ab8500_rtc_alarm_regs[i], buf[i]);
254 if (retval < 0)
255 return retval;
256 }
257
258 return ab8500_rtc_irq_enable(dev, alarm->enabled);
259 }
260
261
ab8500_rtc_set_calibration(struct device * dev,int calibration)262 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
263 {
264 int retval;
265 u8 rtccal = 0;
266
267 /*
268 * Check that the calibration value (which is in units of 0.5
269 * parts-per-million) is in the AB8500's range for RtcCalibration
270 * register. -128 (0x80) is not permitted because the AB8500 uses
271 * a sign-bit rather than two's complement, so 0x80 is just another
272 * representation of zero.
273 */
274 if ((calibration < -127) || (calibration > 127)) {
275 dev_err(dev, "RtcCalibration value outside permitted range\n");
276 return -EINVAL;
277 }
278
279 /*
280 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
281 * so need to convert to this sort of representation before writing
282 * into RtcCalibration register...
283 */
284 if (calibration >= 0)
285 rtccal = 0x7F & calibration;
286 else
287 rtccal = ~(calibration - 1) | 0x80;
288
289 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
290 AB8500_RTC_CALIB_REG, rtccal);
291
292 return retval;
293 }
294
ab8500_rtc_get_calibration(struct device * dev,int * calibration)295 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
296 {
297 int retval;
298 u8 rtccal = 0;
299
300 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
301 AB8500_RTC_CALIB_REG, &rtccal);
302 if (retval >= 0) {
303 /*
304 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
305 * so need to convert value from RtcCalibration register into
306 * a two's complement signed value...
307 */
308 if (rtccal & 0x80)
309 *calibration = 0 - (rtccal & 0x7F);
310 else
311 *calibration = 0x7F & rtccal;
312 }
313
314 return retval;
315 }
316
ab8500_sysfs_store_rtc_calibration(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)317 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
318 struct device_attribute *attr,
319 const char *buf, size_t count)
320 {
321 int retval;
322 int calibration = 0;
323
324 if (sscanf(buf, " %i ", &calibration) != 1) {
325 dev_err(dev, "Failed to store RTC calibration attribute\n");
326 return -EINVAL;
327 }
328
329 retval = ab8500_rtc_set_calibration(dev, calibration);
330
331 return retval ? retval : count;
332 }
333
ab8500_sysfs_show_rtc_calibration(struct device * dev,struct device_attribute * attr,char * buf)334 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
335 struct device_attribute *attr, char *buf)
336 {
337 int retval = 0;
338 int calibration = 0;
339
340 retval = ab8500_rtc_get_calibration(dev, &calibration);
341 if (retval < 0) {
342 dev_err(dev, "Failed to read RTC calibration attribute\n");
343 sprintf(buf, "0\n");
344 return retval;
345 }
346
347 return sprintf(buf, "%d\n", calibration);
348 }
349
350 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
351 ab8500_sysfs_show_rtc_calibration,
352 ab8500_sysfs_store_rtc_calibration);
353
ab8500_sysfs_rtc_register(struct device * dev)354 static int ab8500_sysfs_rtc_register(struct device *dev)
355 {
356 return device_create_file(dev, &dev_attr_rtc_calibration);
357 }
358
ab8500_sysfs_rtc_unregister(struct device * dev)359 static void ab8500_sysfs_rtc_unregister(struct device *dev)
360 {
361 device_remove_file(dev, &dev_attr_rtc_calibration);
362 }
363
rtc_alarm_handler(int irq,void * data)364 static irqreturn_t rtc_alarm_handler(int irq, void *data)
365 {
366 struct rtc_device *rtc = data;
367 unsigned long events = RTC_IRQF | RTC_AF;
368
369 dev_dbg(&rtc->dev, "%s\n", __func__);
370 rtc_update_irq(rtc, 1, events);
371
372 return IRQ_HANDLED;
373 }
374
375 static const struct rtc_class_ops ab8500_rtc_ops = {
376 .read_time = ab8500_rtc_read_time,
377 .set_time = ab8500_rtc_set_time,
378 .read_alarm = ab8500_rtc_read_alarm,
379 .set_alarm = ab8500_rtc_set_alarm,
380 .alarm_irq_enable = ab8500_rtc_irq_enable,
381 };
382
ab8500_rtc_probe(struct platform_device * pdev)383 static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
384 {
385 int err;
386 struct rtc_device *rtc;
387 u8 rtc_ctrl;
388 int irq;
389
390 irq = platform_get_irq_byname(pdev, "ALARM");
391 if (irq < 0)
392 return irq;
393
394 /* For RTC supply test */
395 err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
396 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
397 if (err < 0)
398 return err;
399
400 /* Wait for reset by the PorRtc */
401 usleep_range(1000, 5000);
402
403 err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
404 AB8500_RTC_STAT_REG, &rtc_ctrl);
405 if (err < 0)
406 return err;
407
408 /* Check if the RTC Supply fails */
409 if (!(rtc_ctrl & RTC_STATUS_DATA)) {
410 dev_err(&pdev->dev, "RTC supply failure\n");
411 return -ENODEV;
412 }
413
414 device_init_wakeup(&pdev->dev, true);
415
416 rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
417 THIS_MODULE);
418 if (IS_ERR(rtc)) {
419 dev_err(&pdev->dev, "Registration failed\n");
420 err = PTR_ERR(rtc);
421 return err;
422 }
423
424 err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
425 IRQF_NO_SUSPEND | IRQF_ONESHOT, "ab8500-rtc", rtc);
426 if (err < 0) {
427 rtc_device_unregister(rtc);
428 return err;
429 }
430
431 platform_set_drvdata(pdev, rtc);
432
433
434 err = ab8500_sysfs_rtc_register(&pdev->dev);
435 if (err) {
436 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
437 return err;
438 }
439
440 return 0;
441 }
442
ab8500_rtc_remove(struct platform_device * pdev)443 static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
444 {
445 struct rtc_device *rtc = platform_get_drvdata(pdev);
446 int irq = platform_get_irq_byname(pdev, "ALARM");
447
448 ab8500_sysfs_rtc_unregister(&pdev->dev);
449
450 free_irq(irq, rtc);
451 rtc_device_unregister(rtc);
452 platform_set_drvdata(pdev, NULL);
453
454 return 0;
455 }
456
457 static struct platform_driver ab8500_rtc_driver = {
458 .driver = {
459 .name = "ab8500-rtc",
460 .owner = THIS_MODULE,
461 },
462 .probe = ab8500_rtc_probe,
463 .remove = __devexit_p(ab8500_rtc_remove),
464 };
465
466 module_platform_driver(ab8500_rtc_driver);
467
468 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
469 MODULE_DESCRIPTION("AB8500 RTC Driver");
470 MODULE_LICENSE("GPL v2");
471