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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 #include <linux/pm_wakeirq.h>
 22 
 23 #define AB8500_RTC_SOFF_STAT_REG        0x00
 24 #define AB8500_RTC_CC_CONF_REG          0x01
 25 #define AB8500_RTC_READ_REQ_REG         0x02
 26 #define AB8500_RTC_WATCH_TSECMID_REG    0x03
 27 #define AB8500_RTC_WATCH_TSECHI_REG     0x04
 28 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
 29 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
 30 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
 31 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
 32 #define AB8500_RTC_ALRM_MIN_MID_REG     0x09
 33 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
 34 #define AB8500_RTC_STAT_REG             0x0B
 35 #define AB8500_RTC_BKUP_CHG_REG         0x0C
 36 #define AB8500_RTC_FORCE_BKUP_REG       0x0D
 37 #define AB8500_RTC_CALIB_REG            0x0E
 38 #define AB8500_RTC_SWITCH_STAT_REG      0x0F
 39 #define AB8540_RTC_ALRM_SEC             0x22
 40 #define AB8540_RTC_ALRM_MIN_LOW_REG     0x23
 41 #define AB8540_RTC_ALRM_MIN_MID_REG     0x24
 42 #define AB8540_RTC_ALRM_MIN_HI_REG      0x25
 43 
 44 /* RtcReadRequest bits */
 45 #define RTC_READ_REQUEST                0x01
 46 #define RTC_WRITE_REQUEST               0x02
 47 
 48 /* RtcCtrl bits */
 49 #define RTC_ALARM_ENA                   0x04
 50 #define RTC_STATUS_DATA                 0x01
 51 
 52 #define COUNTS_PER_SEC                  (0xF000 / 60)
 53 #define AB8500_RTC_EPOCH                2000
 54 
 55 static const u8 ab8500_rtc_time_regs[] = {
 56         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
 57         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
 58         AB8500_RTC_WATCH_TSECMID_REG
 59 };
 60 
 61 static const u8 ab8500_rtc_alarm_regs[] = {
 62         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
 63         AB8500_RTC_ALRM_MIN_LOW_REG
 64 };
 65 
 66 static const u8 ab8540_rtc_alarm_regs[] = {
 67         AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
 68         AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
 69 };
 70 
 71 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
 72 static unsigned long get_elapsed_seconds(int year)
 73 {
 74         unsigned long secs;
 75         struct rtc_time tm = {
 76                 .tm_year = year - 1900,
 77                 .tm_mday = 1,
 78         };
 79 
 80         /*
 81          * This function calculates secs from 1970 and not from
 82          * 1900, even if we supply the offset from year 1900.
 83          */
 84         rtc_tm_to_time(&tm, &secs);
 85         return secs;
 86 }
 87 
 88 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
 89 {
 90         unsigned long timeout = jiffies + HZ;
 91         int retval, i;
 92         unsigned long mins, secs;
 93         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 94         u8 value;
 95 
 96         /* Request a data read */
 97         retval = abx500_set_register_interruptible(dev,
 98                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
 99         if (retval < 0)
100                 return retval;
101 
102         /* Wait for some cycles after enabling the rtc read in ab8500 */
103         while (time_before(jiffies, timeout)) {
104                 retval = abx500_get_register_interruptible(dev,
105                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
106                 if (retval < 0)
107                         return retval;
108 
109                 if (!(value & RTC_READ_REQUEST))
110                         break;
111 
112                 usleep_range(1000, 5000);
113         }
114 
115         /* Read the Watchtime registers */
116         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
117                 retval = abx500_get_register_interruptible(dev,
118                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
119                 if (retval < 0)
120                         return retval;
121                 buf[i] = value;
122         }
123 
124         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
125 
126         secs =  (buf[3] << 8) | buf[4];
127         secs =  secs / COUNTS_PER_SEC;
128         secs =  secs + (mins * 60);
129 
130         /* Add back the initially subtracted number of seconds */
131         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
132 
133         rtc_time_to_tm(secs, tm);
134         return rtc_valid_tm(tm);
135 }
136 
137 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
138 {
139         int retval, i;
140         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
141         unsigned long no_secs, no_mins, secs = 0;
142 
143         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
144                 dev_dbg(dev, "year should be equal to or greater than %d\n",
145                                 AB8500_RTC_EPOCH);
146                 return -EINVAL;
147         }
148 
149         /* Get the number of seconds since 1970 */
150         rtc_tm_to_time(tm, &secs);
151 
152         /*
153          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
154          * we only have a small counter in the RTC.
155          */
156         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
157 
158         no_mins = secs / 60;
159 
160         no_secs = secs % 60;
161         /* Make the seconds count as per the RTC resolution */
162         no_secs = no_secs * COUNTS_PER_SEC;
163 
164         buf[4] = no_secs & 0xFF;
165         buf[3] = (no_secs >> 8) & 0xFF;
166 
167         buf[2] = no_mins & 0xFF;
168         buf[1] = (no_mins >> 8) & 0xFF;
169         buf[0] = (no_mins >> 16) & 0xFF;
170 
171         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
172                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
173                         ab8500_rtc_time_regs[i], buf[i]);
174                 if (retval < 0)
175                         return retval;
176         }
177 
178         /* Request a data write */
179         return abx500_set_register_interruptible(dev, AB8500_RTC,
180                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
181 }
182 
183 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
184 {
185         int retval, i;
186         u8 rtc_ctrl, value;
187         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
188         unsigned long secs, mins;
189 
190         /* Check if the alarm is enabled or not */
191         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
192                 AB8500_RTC_STAT_REG, &rtc_ctrl);
193         if (retval < 0)
194                 return retval;
195 
196         if (rtc_ctrl & RTC_ALARM_ENA)
197                 alarm->enabled = 1;
198         else
199                 alarm->enabled = 0;
200 
201         alarm->pending = 0;
202 
203         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
204                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
205                         ab8500_rtc_alarm_regs[i], &value);
206                 if (retval < 0)
207                         return retval;
208                 buf[i] = value;
209         }
210 
211         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
212         secs = mins * 60;
213 
214         /* Add back the initially subtracted number of seconds */
215         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
216 
217         rtc_time_to_tm(secs, &alarm->time);
218 
219         return rtc_valid_tm(&alarm->time);
220 }
221 
222 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
223 {
224         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
225                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
226                 enabled ? RTC_ALARM_ENA : 0);
227 }
228 
229 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
230 {
231         int retval, i;
232         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
233         unsigned long mins, secs = 0, cursec = 0;
234         struct rtc_time curtm;
235 
236         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
237                 dev_dbg(dev, "year should be equal to or greater than %d\n",
238                                 AB8500_RTC_EPOCH);
239                 return -EINVAL;
240         }
241 
242         /* Get the number of seconds since 1970 */
243         rtc_tm_to_time(&alarm->time, &secs);
244 
245         /*
246          * Check whether alarm is set less than 1min.
247          * Since our RTC doesn't support alarm resolution less than 1min,
248          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
249          */
250         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
251         rtc_tm_to_time(&curtm, &cursec);
252         if ((secs - cursec) < 59) {
253                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
254                 return -EINVAL;
255         }
256 
257         /*
258          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
259          * we only have a small counter in the RTC.
260          */
261         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
262 
263         mins = secs / 60;
264 
265         buf[2] = mins & 0xFF;
266         buf[1] = (mins >> 8) & 0xFF;
267         buf[0] = (mins >> 16) & 0xFF;
268 
269         /* Set the alarm time */
270         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
271                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
272                         ab8500_rtc_alarm_regs[i], buf[i]);
273                 if (retval < 0)
274                         return retval;
275         }
276 
277         return ab8500_rtc_irq_enable(dev, alarm->enabled);
278 }
279 
280 static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
281 {
282         int retval, i;
283         unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
284         unsigned long mins, secs = 0;
285 
286         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
287                 dev_dbg(dev, "year should be equal to or greater than %d\n",
288                                 AB8500_RTC_EPOCH);
289                 return -EINVAL;
290         }
291 
292         /* Get the number of seconds since 1970 */
293         rtc_tm_to_time(&alarm->time, &secs);
294 
295         /*
296          * Convert it to the number of seconds since 01-01-2000 00:00:00
297          */
298         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
299         mins = secs / 60;
300 
301         buf[3] = secs % 60;
302         buf[2] = mins & 0xFF;
303         buf[1] = (mins >> 8) & 0xFF;
304         buf[0] = (mins >> 16) & 0xFF;
305 
306         /* Set the alarm time */
307         for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
308                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
309                         ab8540_rtc_alarm_regs[i], buf[i]);
310                 if (retval < 0)
311                         return retval;
312         }
313 
314         return ab8500_rtc_irq_enable(dev, alarm->enabled);
315 }
316 
317 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
318 {
319         int retval;
320         u8  rtccal = 0;
321 
322         /*
323          * Check that the calibration value (which is in units of 0.5
324          * parts-per-million) is in the AB8500's range for RtcCalibration
325          * register. -128 (0x80) is not permitted because the AB8500 uses
326          * a sign-bit rather than two's complement, so 0x80 is just another
327          * representation of zero.
328          */
329         if ((calibration < -127) || (calibration > 127)) {
330                 dev_err(dev, "RtcCalibration value outside permitted range\n");
331                 return -EINVAL;
332         }
333 
334         /*
335          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
336          * so need to convert to this sort of representation before writing
337          * into RtcCalibration register...
338          */
339         if (calibration >= 0)
340                 rtccal = 0x7F & calibration;
341         else
342                 rtccal = ~(calibration - 1) | 0x80;
343 
344         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
345                         AB8500_RTC_CALIB_REG, rtccal);
346 
347         return retval;
348 }
349 
350 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
351 {
352         int retval;
353         u8  rtccal = 0;
354 
355         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
356                         AB8500_RTC_CALIB_REG, &rtccal);
357         if (retval >= 0) {
358                 /*
359                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
360                  * so need to convert value from RtcCalibration register into
361                  * a two's complement signed value...
362                  */
363                 if (rtccal & 0x80)
364                         *calibration = 0 - (rtccal & 0x7F);
365                 else
366                         *calibration = 0x7F & rtccal;
367         }
368 
369         return retval;
370 }
371 
372 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
373                                 struct device_attribute *attr,
374                                 const char *buf, size_t count)
375 {
376         int retval;
377         int calibration = 0;
378 
379         if (sscanf(buf, " %i ", &calibration) != 1) {
380                 dev_err(dev, "Failed to store RTC calibration attribute\n");
381                 return -EINVAL;
382         }
383 
384         retval = ab8500_rtc_set_calibration(dev, calibration);
385 
386         return retval ? retval : count;
387 }
388 
389 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
390                                 struct device_attribute *attr, char *buf)
391 {
392         int  retval = 0;
393         int  calibration = 0;
394 
395         retval = ab8500_rtc_get_calibration(dev, &calibration);
396         if (retval < 0) {
397                 dev_err(dev, "Failed to read RTC calibration attribute\n");
398                 sprintf(buf, "\n");
399                 return retval;
400         }
401 
402         return sprintf(buf, "%d\n", calibration);
403 }
404 
405 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
406                    ab8500_sysfs_show_rtc_calibration,
407                    ab8500_sysfs_store_rtc_calibration);
408 
409 static int ab8500_sysfs_rtc_register(struct device *dev)
410 {
411         return device_create_file(dev, &dev_attr_rtc_calibration);
412 }
413 
414 static void ab8500_sysfs_rtc_unregister(struct device *dev)
415 {
416         device_remove_file(dev, &dev_attr_rtc_calibration);
417 }
418 
419 static irqreturn_t rtc_alarm_handler(int irq, void *data)
420 {
421         struct rtc_device *rtc = data;
422         unsigned long events = RTC_IRQF | RTC_AF;
423 
424         dev_dbg(&rtc->dev, "%s\n", __func__);
425         rtc_update_irq(rtc, 1, events);
426 
427         return IRQ_HANDLED;
428 }
429 
430 static const struct rtc_class_ops ab8500_rtc_ops = {
431         .read_time              = ab8500_rtc_read_time,
432         .set_time               = ab8500_rtc_set_time,
433         .read_alarm             = ab8500_rtc_read_alarm,
434         .set_alarm              = ab8500_rtc_set_alarm,
435         .alarm_irq_enable       = ab8500_rtc_irq_enable,
436 };
437 
438 static const struct rtc_class_ops ab8540_rtc_ops = {
439         .read_time              = ab8500_rtc_read_time,
440         .set_time               = ab8500_rtc_set_time,
441         .read_alarm             = ab8500_rtc_read_alarm,
442         .set_alarm              = ab8540_rtc_set_alarm,
443         .alarm_irq_enable       = ab8500_rtc_irq_enable,
444 };
445 
446 static const struct platform_device_id ab85xx_rtc_ids[] = {
447         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
448         { "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
449         { /* sentinel */ }
450 };
451 MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
452 
453 static int ab8500_rtc_probe(struct platform_device *pdev)
454 {
455         const struct platform_device_id *platid = platform_get_device_id(pdev);
456         int err;
457         struct rtc_device *rtc;
458         u8 rtc_ctrl;
459         int irq;
460 
461         irq = platform_get_irq_byname(pdev, "ALARM");
462         if (irq < 0)
463                 return irq;
464 
465         /* For RTC supply test */
466         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
467                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
468         if (err < 0)
469                 return err;
470 
471         /* Wait for reset by the PorRtc */
472         usleep_range(1000, 5000);
473 
474         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
475                 AB8500_RTC_STAT_REG, &rtc_ctrl);
476         if (err < 0)
477                 return err;
478 
479         /* Check if the RTC Supply fails */
480         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
481                 dev_err(&pdev->dev, "RTC supply failure\n");
482                 return -ENODEV;
483         }
484 
485         device_init_wakeup(&pdev->dev, true);
486 
487         rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
488                                 (struct rtc_class_ops *)platid->driver_data,
489                                 THIS_MODULE);
490         if (IS_ERR(rtc)) {
491                 dev_err(&pdev->dev, "Registration failed\n");
492                 err = PTR_ERR(rtc);
493                 return err;
494         }
495 
496         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
497                         rtc_alarm_handler, IRQF_ONESHOT,
498                         "ab8500-rtc", rtc);
499         if (err < 0)
500                 return err;
501 
502         dev_pm_set_wake_irq(&pdev->dev, irq);
503         platform_set_drvdata(pdev, rtc);
504 
505         err = ab8500_sysfs_rtc_register(&pdev->dev);
506         if (err) {
507                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
508                 return err;
509         }
510 
511         rtc->uie_unsupported = 1;
512 
513         return 0;
514 }
515 
516 static int ab8500_rtc_remove(struct platform_device *pdev)
517 {
518         dev_pm_clear_wake_irq(&pdev->dev);
519         device_init_wakeup(&pdev->dev, false);
520         ab8500_sysfs_rtc_unregister(&pdev->dev);
521 
522         return 0;
523 }
524 
525 static struct platform_driver ab8500_rtc_driver = {
526         .driver = {
527                 .name = "ab8500-rtc",
528         },
529         .probe  = ab8500_rtc_probe,
530         .remove = ab8500_rtc_remove,
531         .id_table = ab85xx_rtc_ids,
532 };
533 
534 module_platform_driver(ab8500_rtc_driver);
535 
536 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
537 MODULE_DESCRIPTION("AB8500 RTC Driver");
538 MODULE_LICENSE("GPL v2");
539 

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