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Linux/drivers/rtc/rtc-ab8500.c

  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 
 22 #define AB8500_RTC_SOFF_STAT_REG        0x00
 23 #define AB8500_RTC_CC_CONF_REG          0x01
 24 #define AB8500_RTC_READ_REQ_REG         0x02
 25 #define AB8500_RTC_WATCH_TSECMID_REG    0x03
 26 #define AB8500_RTC_WATCH_TSECHI_REG     0x04
 27 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
 28 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
 29 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
 30 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
 31 #define AB8500_RTC_ALRM_MIN_MID_REG     0x09
 32 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
 33 #define AB8500_RTC_STAT_REG             0x0B
 34 #define AB8500_RTC_BKUP_CHG_REG         0x0C
 35 #define AB8500_RTC_FORCE_BKUP_REG       0x0D
 36 #define AB8500_RTC_CALIB_REG            0x0E
 37 #define AB8500_RTC_SWITCH_STAT_REG      0x0F
 38 #define AB8540_RTC_ALRM_SEC             0x22
 39 #define AB8540_RTC_ALRM_MIN_LOW_REG     0x23
 40 #define AB8540_RTC_ALRM_MIN_MID_REG     0x24
 41 #define AB8540_RTC_ALRM_MIN_HI_REG      0x25
 42 
 43 /* RtcReadRequest bits */
 44 #define RTC_READ_REQUEST                0x01
 45 #define RTC_WRITE_REQUEST               0x02
 46 
 47 /* RtcCtrl bits */
 48 #define RTC_ALARM_ENA                   0x04
 49 #define RTC_STATUS_DATA                 0x01
 50 
 51 #define COUNTS_PER_SEC                  (0xF000 / 60)
 52 #define AB8500_RTC_EPOCH                2000
 53 
 54 static const u8 ab8500_rtc_time_regs[] = {
 55         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
 56         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
 57         AB8500_RTC_WATCH_TSECMID_REG
 58 };
 59 
 60 static const u8 ab8500_rtc_alarm_regs[] = {
 61         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
 62         AB8500_RTC_ALRM_MIN_LOW_REG
 63 };
 64 
 65 static const u8 ab8540_rtc_alarm_regs[] = {
 66         AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
 67         AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
 68 };
 69 
 70 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
 71 static unsigned long get_elapsed_seconds(int year)
 72 {
 73         unsigned long secs;
 74         struct rtc_time tm = {
 75                 .tm_year = year - 1900,
 76                 .tm_mday = 1,
 77         };
 78 
 79         /*
 80          * This function calculates secs from 1970 and not from
 81          * 1900, even if we supply the offset from year 1900.
 82          */
 83         rtc_tm_to_time(&tm, &secs);
 84         return secs;
 85 }
 86 
 87 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
 88 {
 89         unsigned long timeout = jiffies + HZ;
 90         int retval, i;
 91         unsigned long mins, secs;
 92         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 93         u8 value;
 94 
 95         /* Request a data read */
 96         retval = abx500_set_register_interruptible(dev,
 97                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
 98         if (retval < 0)
 99                 return retval;
100 
101         /* Wait for some cycles after enabling the rtc read in ab8500 */
102         while (time_before(jiffies, timeout)) {
103                 retval = abx500_get_register_interruptible(dev,
104                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
105                 if (retval < 0)
106                         return retval;
107 
108                 if (!(value & RTC_READ_REQUEST))
109                         break;
110 
111                 usleep_range(1000, 5000);
112         }
113 
114         /* Read the Watchtime registers */
115         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
116                 retval = abx500_get_register_interruptible(dev,
117                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
118                 if (retval < 0)
119                         return retval;
120                 buf[i] = value;
121         }
122 
123         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
124 
125         secs =  (buf[3] << 8) | buf[4];
126         secs =  secs / COUNTS_PER_SEC;
127         secs =  secs + (mins * 60);
128 
129         /* Add back the initially subtracted number of seconds */
130         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
131 
132         rtc_time_to_tm(secs, tm);
133         return rtc_valid_tm(tm);
134 }
135 
136 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
137 {
138         int retval, i;
139         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
140         unsigned long no_secs, no_mins, secs = 0;
141 
142         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
143                 dev_dbg(dev, "year should be equal to or greater than %d\n",
144                                 AB8500_RTC_EPOCH);
145                 return -EINVAL;
146         }
147 
148         /* Get the number of seconds since 1970 */
149         rtc_tm_to_time(tm, &secs);
150 
151         /*
152          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
153          * we only have a small counter in the RTC.
154          */
155         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
156 
157         no_mins = secs / 60;
158 
159         no_secs = secs % 60;
160         /* Make the seconds count as per the RTC resolution */
161         no_secs = no_secs * COUNTS_PER_SEC;
162 
163         buf[4] = no_secs & 0xFF;
164         buf[3] = (no_secs >> 8) & 0xFF;
165 
166         buf[2] = no_mins & 0xFF;
167         buf[1] = (no_mins >> 8) & 0xFF;
168         buf[0] = (no_mins >> 16) & 0xFF;
169 
170         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
171                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
172                         ab8500_rtc_time_regs[i], buf[i]);
173                 if (retval < 0)
174                         return retval;
175         }
176 
177         /* Request a data write */
178         return abx500_set_register_interruptible(dev, AB8500_RTC,
179                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
180 }
181 
182 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
183 {
184         int retval, i;
185         u8 rtc_ctrl, value;
186         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
187         unsigned long secs, mins;
188 
189         /* Check if the alarm is enabled or not */
190         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
191                 AB8500_RTC_STAT_REG, &rtc_ctrl);
192         if (retval < 0)
193                 return retval;
194 
195         if (rtc_ctrl & RTC_ALARM_ENA)
196                 alarm->enabled = 1;
197         else
198                 alarm->enabled = 0;
199 
200         alarm->pending = 0;
201 
202         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
203                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
204                         ab8500_rtc_alarm_regs[i], &value);
205                 if (retval < 0)
206                         return retval;
207                 buf[i] = value;
208         }
209 
210         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
211         secs = mins * 60;
212 
213         /* Add back the initially subtracted number of seconds */
214         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
215 
216         rtc_time_to_tm(secs, &alarm->time);
217 
218         return rtc_valid_tm(&alarm->time);
219 }
220 
221 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
222 {
223         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
224                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
225                 enabled ? RTC_ALARM_ENA : 0);
226 }
227 
228 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
229 {
230         int retval, i;
231         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
232         unsigned long mins, secs = 0, cursec = 0;
233         struct rtc_time curtm;
234 
235         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
236                 dev_dbg(dev, "year should be equal to or greater than %d\n",
237                                 AB8500_RTC_EPOCH);
238                 return -EINVAL;
239         }
240 
241         /* Get the number of seconds since 1970 */
242         rtc_tm_to_time(&alarm->time, &secs);
243 
244         /*
245          * Check whether alarm is set less than 1min.
246          * Since our RTC doesn't support alarm resolution less than 1min,
247          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
248          */
249         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
250         rtc_tm_to_time(&curtm, &cursec);
251         if ((secs - cursec) < 59) {
252                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
253                 return -EINVAL;
254         }
255 
256         /*
257          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
258          * we only have a small counter in the RTC.
259          */
260         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
261 
262         mins = secs / 60;
263 
264         buf[2] = mins & 0xFF;
265         buf[1] = (mins >> 8) & 0xFF;
266         buf[0] = (mins >> 16) & 0xFF;
267 
268         /* Set the alarm time */
269         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
270                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
271                         ab8500_rtc_alarm_regs[i], buf[i]);
272                 if (retval < 0)
273                         return retval;
274         }
275 
276         return ab8500_rtc_irq_enable(dev, alarm->enabled);
277 }
278 
279 static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
280 {
281         int retval, i;
282         unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
283         unsigned long mins, secs = 0;
284 
285         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
286                 dev_dbg(dev, "year should be equal to or greater than %d\n",
287                                 AB8500_RTC_EPOCH);
288                 return -EINVAL;
289         }
290 
291         /* Get the number of seconds since 1970 */
292         rtc_tm_to_time(&alarm->time, &secs);
293 
294         /*
295          * Convert it to the number of seconds since 01-01-2000 00:00:00
296          */
297         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
298         mins = secs / 60;
299 
300         buf[3] = secs % 60;
301         buf[2] = mins & 0xFF;
302         buf[1] = (mins >> 8) & 0xFF;
303         buf[0] = (mins >> 16) & 0xFF;
304 
305         /* Set the alarm time */
306         for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
307                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
308                         ab8540_rtc_alarm_regs[i], buf[i]);
309                 if (retval < 0)
310                         return retval;
311         }
312 
313         return ab8500_rtc_irq_enable(dev, alarm->enabled);
314 }
315 
316 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
317 {
318         int retval;
319         u8  rtccal = 0;
320 
321         /*
322          * Check that the calibration value (which is in units of 0.5
323          * parts-per-million) is in the AB8500's range for RtcCalibration
324          * register. -128 (0x80) is not permitted because the AB8500 uses
325          * a sign-bit rather than two's complement, so 0x80 is just another
326          * representation of zero.
327          */
328         if ((calibration < -127) || (calibration > 127)) {
329                 dev_err(dev, "RtcCalibration value outside permitted range\n");
330                 return -EINVAL;
331         }
332 
333         /*
334          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
335          * so need to convert to this sort of representation before writing
336          * into RtcCalibration register...
337          */
338         if (calibration >= 0)
339                 rtccal = 0x7F & calibration;
340         else
341                 rtccal = ~(calibration - 1) | 0x80;
342 
343         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
344                         AB8500_RTC_CALIB_REG, rtccal);
345 
346         return retval;
347 }
348 
349 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
350 {
351         int retval;
352         u8  rtccal = 0;
353 
354         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
355                         AB8500_RTC_CALIB_REG, &rtccal);
356         if (retval >= 0) {
357                 /*
358                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
359                  * so need to convert value from RtcCalibration register into
360                  * a two's complement signed value...
361                  */
362                 if (rtccal & 0x80)
363                         *calibration = 0 - (rtccal & 0x7F);
364                 else
365                         *calibration = 0x7F & rtccal;
366         }
367 
368         return retval;
369 }
370 
371 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
372                                 struct device_attribute *attr,
373                                 const char *buf, size_t count)
374 {
375         int retval;
376         int calibration = 0;
377 
378         if (sscanf(buf, " %i ", &calibration) != 1) {
379                 dev_err(dev, "Failed to store RTC calibration attribute\n");
380                 return -EINVAL;
381         }
382 
383         retval = ab8500_rtc_set_calibration(dev, calibration);
384 
385         return retval ? retval : count;
386 }
387 
388 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
389                                 struct device_attribute *attr, char *buf)
390 {
391         int  retval = 0;
392         int  calibration = 0;
393 
394         retval = ab8500_rtc_get_calibration(dev, &calibration);
395         if (retval < 0) {
396                 dev_err(dev, "Failed to read RTC calibration attribute\n");
397                 sprintf(buf, "\n");
398                 return retval;
399         }
400 
401         return sprintf(buf, "%d\n", calibration);
402 }
403 
404 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
405                    ab8500_sysfs_show_rtc_calibration,
406                    ab8500_sysfs_store_rtc_calibration);
407 
408 static int ab8500_sysfs_rtc_register(struct device *dev)
409 {
410         return device_create_file(dev, &dev_attr_rtc_calibration);
411 }
412 
413 static void ab8500_sysfs_rtc_unregister(struct device *dev)
414 {
415         device_remove_file(dev, &dev_attr_rtc_calibration);
416 }
417 
418 static irqreturn_t rtc_alarm_handler(int irq, void *data)
419 {
420         struct rtc_device *rtc = data;
421         unsigned long events = RTC_IRQF | RTC_AF;
422 
423         dev_dbg(&rtc->dev, "%s\n", __func__);
424         rtc_update_irq(rtc, 1, events);
425 
426         return IRQ_HANDLED;
427 }
428 
429 static const struct rtc_class_ops ab8500_rtc_ops = {
430         .read_time              = ab8500_rtc_read_time,
431         .set_time               = ab8500_rtc_set_time,
432         .read_alarm             = ab8500_rtc_read_alarm,
433         .set_alarm              = ab8500_rtc_set_alarm,
434         .alarm_irq_enable       = ab8500_rtc_irq_enable,
435 };
436 
437 static const struct rtc_class_ops ab8540_rtc_ops = {
438         .read_time              = ab8500_rtc_read_time,
439         .set_time               = ab8500_rtc_set_time,
440         .read_alarm             = ab8500_rtc_read_alarm,
441         .set_alarm              = ab8540_rtc_set_alarm,
442         .alarm_irq_enable       = ab8500_rtc_irq_enable,
443 };
444 
445 static struct platform_device_id ab85xx_rtc_ids[] = {
446         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
447         { "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
448 };
449 
450 static int ab8500_rtc_probe(struct platform_device *pdev)
451 {
452         const struct platform_device_id *platid = platform_get_device_id(pdev);
453         int err;
454         struct rtc_device *rtc;
455         u8 rtc_ctrl;
456         int irq;
457 
458         irq = platform_get_irq_byname(pdev, "ALARM");
459         if (irq < 0)
460                 return irq;
461 
462         /* For RTC supply test */
463         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
464                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
465         if (err < 0)
466                 return err;
467 
468         /* Wait for reset by the PorRtc */
469         usleep_range(1000, 5000);
470 
471         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
472                 AB8500_RTC_STAT_REG, &rtc_ctrl);
473         if (err < 0)
474                 return err;
475 
476         /* Check if the RTC Supply fails */
477         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
478                 dev_err(&pdev->dev, "RTC supply failure\n");
479                 return -ENODEV;
480         }
481 
482         device_init_wakeup(&pdev->dev, true);
483 
484         rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
485                                 (struct rtc_class_ops *)platid->driver_data,
486                                 THIS_MODULE);
487         if (IS_ERR(rtc)) {
488                 dev_err(&pdev->dev, "Registration failed\n");
489                 err = PTR_ERR(rtc);
490                 return err;
491         }
492 
493         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
494                         rtc_alarm_handler, IRQF_NO_SUSPEND | IRQF_ONESHOT,
495                         "ab8500-rtc", rtc);
496         if (err < 0)
497                 return err;
498 
499         platform_set_drvdata(pdev, rtc);
500 
501         err = ab8500_sysfs_rtc_register(&pdev->dev);
502         if (err) {
503                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
504                 return err;
505         }
506 
507         return 0;
508 }
509 
510 static int ab8500_rtc_remove(struct platform_device *pdev)
511 {
512         ab8500_sysfs_rtc_unregister(&pdev->dev);
513 
514         return 0;
515 }
516 
517 static struct platform_driver ab8500_rtc_driver = {
518         .driver = {
519                 .name = "ab8500-rtc",
520                 .owner = THIS_MODULE,
521         },
522         .probe  = ab8500_rtc_probe,
523         .remove = ab8500_rtc_remove,
524         .id_table = ab85xx_rtc_ids,
525 };
526 
527 module_platform_driver(ab8500_rtc_driver);
528 
529 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
530 MODULE_DESCRIPTION("AB8500 RTC Driver");
531 MODULE_LICENSE("GPL v2");
532 

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