Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

Linux/drivers/rtc/rtc-wm831x.c

  1 /*
  2  *      Real Time Clock driver for Wolfson Microelectronics WM831x
  3  *
  4  *      Copyright (C) 2009 Wolfson Microelectronics PLC.
  5  *
  6  *  Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
  7  *
  8  *  This program is free software; you can redistribute  it and/or modify it
  9  *  under  the terms of  the GNU General  Public License as published by the
 10  *  Free Software Foundation;  either version 2 of the  License, or (at your
 11  *  option) any later version.
 12  *
 13  */
 14 
 15 #include <linux/module.h>
 16 #include <linux/kernel.h>
 17 #include <linux/time.h>
 18 #include <linux/rtc.h>
 19 #include <linux/slab.h>
 20 #include <linux/bcd.h>
 21 #include <linux/interrupt.h>
 22 #include <linux/ioctl.h>
 23 #include <linux/completion.h>
 24 #include <linux/mfd/wm831x/core.h>
 25 #include <linux/delay.h>
 26 #include <linux/platform_device.h>
 27 #include <linux/random.h>
 28 
 29 /*
 30  * R16416 (0x4020) - RTC Write Counter
 31  */
 32 #define WM831X_RTC_WR_CNT_MASK                  0xFFFF  /* RTC_WR_CNT - [15:0] */
 33 #define WM831X_RTC_WR_CNT_SHIFT                      0  /* RTC_WR_CNT - [15:0] */
 34 #define WM831X_RTC_WR_CNT_WIDTH                     16  /* RTC_WR_CNT - [15:0] */
 35 
 36 /*
 37  * R16417 (0x4021) - RTC Time 1
 38  */
 39 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
 40 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
 41 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
 42 
 43 /*
 44  * R16418 (0x4022) - RTC Time 2
 45  */
 46 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
 47 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
 48 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
 49 
 50 /*
 51  * R16419 (0x4023) - RTC Alarm 1
 52  */
 53 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
 54 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
 55 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
 56 
 57 /*
 58  * R16420 (0x4024) - RTC Alarm 2
 59  */
 60 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
 61 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
 62 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
 63 
 64 /*
 65  * R16421 (0x4025) - RTC Control
 66  */
 67 #define WM831X_RTC_VALID                        0x8000  /* RTC_VALID */
 68 #define WM831X_RTC_VALID_MASK                   0x8000  /* RTC_VALID */
 69 #define WM831X_RTC_VALID_SHIFT                      15  /* RTC_VALID */
 70 #define WM831X_RTC_VALID_WIDTH                       1  /* RTC_VALID */
 71 #define WM831X_RTC_SYNC_BUSY                    0x4000  /* RTC_SYNC_BUSY */
 72 #define WM831X_RTC_SYNC_BUSY_MASK               0x4000  /* RTC_SYNC_BUSY */
 73 #define WM831X_RTC_SYNC_BUSY_SHIFT                  14  /* RTC_SYNC_BUSY */
 74 #define WM831X_RTC_SYNC_BUSY_WIDTH                   1  /* RTC_SYNC_BUSY */
 75 #define WM831X_RTC_ALM_ENA                      0x0400  /* RTC_ALM_ENA */
 76 #define WM831X_RTC_ALM_ENA_MASK                 0x0400  /* RTC_ALM_ENA */
 77 #define WM831X_RTC_ALM_ENA_SHIFT                    10  /* RTC_ALM_ENA */
 78 #define WM831X_RTC_ALM_ENA_WIDTH                     1  /* RTC_ALM_ENA */
 79 #define WM831X_RTC_PINT_FREQ_MASK               0x0070  /* RTC_PINT_FREQ - [6:4] */
 80 #define WM831X_RTC_PINT_FREQ_SHIFT                   4  /* RTC_PINT_FREQ - [6:4] */
 81 #define WM831X_RTC_PINT_FREQ_WIDTH                   3  /* RTC_PINT_FREQ - [6:4] */
 82 
 83 /*
 84  * R16422 (0x4026) - RTC Trim
 85  */
 86 #define WM831X_RTC_TRIM_MASK                    0x03FF  /* RTC_TRIM - [9:0] */
 87 #define WM831X_RTC_TRIM_SHIFT                        0  /* RTC_TRIM - [9:0] */
 88 #define WM831X_RTC_TRIM_WIDTH                       10  /* RTC_TRIM - [9:0] */
 89 
 90 #define WM831X_SET_TIME_RETRIES 5
 91 #define WM831X_GET_TIME_RETRIES 5
 92 
 93 struct wm831x_rtc {
 94         struct wm831x *wm831x;
 95         struct rtc_device *rtc;
 96         unsigned int alarm_enabled:1;
 97 };
 98 
 99 static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
100 {
101         int ret;
102         u16 reg;
103 
104         /*
105          * The write counter contains a pseudo-random number which is
106          * regenerated every time we set the RTC so it should be a
107          * useful per-system source of entropy.
108          */
109         ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
110         if (ret >= 0) {
111                 reg = ret;
112                 add_device_randomness(&reg, sizeof(reg));
113         } else {
114                 dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n",
115                          ret);
116         }
117 }
118 
119 /*
120  * Read current time and date in RTC
121  */
122 static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
123 {
124         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
125         struct wm831x *wm831x = wm831x_rtc->wm831x;
126         u16 time1[2], time2[2];
127         int ret;
128         int count = 0;
129 
130         /* Has the RTC been programmed? */
131         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
132         if (ret < 0) {
133                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
134                 return ret;
135         }
136         if (!(ret & WM831X_RTC_VALID)) {
137                 dev_dbg(dev, "RTC not yet configured\n");
138                 return -EINVAL;
139         }
140 
141         /* Read twice to make sure we don't read a corrupt, partially
142          * incremented, value.
143          */
144         do {
145                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
146                                        2, time1);
147                 if (ret != 0)
148                         continue;
149 
150                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
151                                        2, time2);
152                 if (ret != 0)
153                         continue;
154 
155                 if (memcmp(time1, time2, sizeof(time1)) == 0) {
156                         u32 time = (time1[0] << 16) | time1[1];
157 
158                         rtc_time_to_tm(time, tm);
159                         return rtc_valid_tm(tm);
160                 }
161 
162         } while (++count < WM831X_GET_TIME_RETRIES);
163 
164         dev_err(dev, "Timed out reading current time\n");
165 
166         return -EIO;
167 }
168 
169 /*
170  * Set current time and date in RTC
171  */
172 static int wm831x_rtc_set_mmss(struct device *dev, unsigned long time)
173 {
174         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
175         struct wm831x *wm831x = wm831x_rtc->wm831x;
176         struct rtc_time new_tm;
177         unsigned long new_time;
178         int ret;
179         int count = 0;
180 
181         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
182                                (time >> 16) & 0xffff);
183         if (ret < 0) {
184                 dev_err(dev, "Failed to write TIME_1: %d\n", ret);
185                 return ret;
186         }
187 
188         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
189         if (ret < 0) {
190                 dev_err(dev, "Failed to write TIME_2: %d\n", ret);
191                 return ret;
192         }
193 
194         /* Wait for the update to complete - should happen first time
195          * round but be conservative.
196          */
197         do {
198                 msleep(1);
199 
200                 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
201                 if (ret < 0)
202                         ret = WM831X_RTC_SYNC_BUSY;
203         } while (!(ret & WM831X_RTC_SYNC_BUSY) &&
204                  ++count < WM831X_SET_TIME_RETRIES);
205 
206         if (ret & WM831X_RTC_SYNC_BUSY) {
207                 dev_err(dev, "Timed out writing RTC update\n");
208                 return -EIO;
209         }
210 
211         /* Check that the update was accepted; security features may
212          * have caused the update to be ignored.
213          */
214         ret = wm831x_rtc_readtime(dev, &new_tm);
215         if (ret < 0)
216                 return ret;
217 
218         ret = rtc_tm_to_time(&new_tm, &new_time);
219         if (ret < 0) {
220                 dev_err(dev, "Failed to convert time: %d\n", ret);
221                 return ret;
222         }
223 
224         /* Allow a second of change in case of tick */
225         if (new_time - time > 1) {
226                 dev_err(dev, "RTC update not permitted by hardware\n");
227                 return -EPERM;
228         }
229 
230         return 0;
231 }
232 
233 /*
234  * Read alarm time and date in RTC
235  */
236 static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
237 {
238         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
239         int ret;
240         u16 data[2];
241         u32 time;
242 
243         ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
244                                2, data);
245         if (ret != 0) {
246                 dev_err(dev, "Failed to read alarm time: %d\n", ret);
247                 return ret;
248         }
249 
250         time = (data[0] << 16) | data[1];
251 
252         rtc_time_to_tm(time, &alrm->time);
253 
254         ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
255         if (ret < 0) {
256                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
257                 return ret;
258         }
259 
260         if (ret & WM831X_RTC_ALM_ENA)
261                 alrm->enabled = 1;
262         else
263                 alrm->enabled = 0;
264 
265         return 0;
266 }
267 
268 static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
269 {
270         wm831x_rtc->alarm_enabled = 0;
271 
272         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
273                                WM831X_RTC_ALM_ENA, 0);
274 }
275 
276 static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
277 {
278         wm831x_rtc->alarm_enabled = 1;
279 
280         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
281                                WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
282 }
283 
284 static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
285 {
286         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
287         struct wm831x *wm831x = wm831x_rtc->wm831x;
288         int ret;
289         unsigned long time;
290 
291         ret = rtc_tm_to_time(&alrm->time, &time);
292         if (ret < 0) {
293                 dev_err(dev, "Failed to convert time: %d\n", ret);
294                 return ret;
295         }
296 
297         ret = wm831x_rtc_stop_alarm(wm831x_rtc);
298         if (ret < 0) {
299                 dev_err(dev, "Failed to stop alarm: %d\n", ret);
300                 return ret;
301         }
302 
303         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
304                                (time >> 16) & 0xffff);
305         if (ret < 0) {
306                 dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
307                 return ret;
308         }
309 
310         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
311         if (ret < 0) {
312                 dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
313                 return ret;
314         }
315 
316         if (alrm->enabled) {
317                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
318                 if (ret < 0) {
319                         dev_err(dev, "Failed to start alarm: %d\n", ret);
320                         return ret;
321                 }
322         }
323 
324         return 0;
325 }
326 
327 static int wm831x_rtc_alarm_irq_enable(struct device *dev,
328                                        unsigned int enabled)
329 {
330         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
331 
332         if (enabled)
333                 return wm831x_rtc_start_alarm(wm831x_rtc);
334         else
335                 return wm831x_rtc_stop_alarm(wm831x_rtc);
336 }
337 
338 static irqreturn_t wm831x_alm_irq(int irq, void *data)
339 {
340         struct wm831x_rtc *wm831x_rtc = data;
341 
342         rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
343 
344         return IRQ_HANDLED;
345 }
346 
347 static const struct rtc_class_ops wm831x_rtc_ops = {
348         .read_time = wm831x_rtc_readtime,
349         .set_mmss = wm831x_rtc_set_mmss,
350         .read_alarm = wm831x_rtc_readalarm,
351         .set_alarm = wm831x_rtc_setalarm,
352         .alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
353 };
354 
355 #ifdef CONFIG_PM
356 /* Turn off the alarm if it should not be a wake source. */
357 static int wm831x_rtc_suspend(struct device *dev)
358 {
359         struct platform_device *pdev = to_platform_device(dev);
360         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
361         int ret, enable;
362 
363         if (wm831x_rtc->alarm_enabled && device_may_wakeup(&pdev->dev))
364                 enable = WM831X_RTC_ALM_ENA;
365         else
366                 enable = 0;
367 
368         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
369                               WM831X_RTC_ALM_ENA, enable);
370         if (ret != 0)
371                 dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret);
372 
373         return 0;
374 }
375 
376 /* Enable the alarm if it should be enabled (in case it was disabled to
377  * prevent use as a wake source).
378  */
379 static int wm831x_rtc_resume(struct device *dev)
380 {
381         struct platform_device *pdev = to_platform_device(dev);
382         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
383         int ret;
384 
385         if (wm831x_rtc->alarm_enabled) {
386                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
387                 if (ret != 0)
388                         dev_err(&pdev->dev,
389                                 "Failed to restart RTC alarm: %d\n", ret);
390         }
391 
392         return 0;
393 }
394 
395 /* Unconditionally disable the alarm */
396 static int wm831x_rtc_freeze(struct device *dev)
397 {
398         struct platform_device *pdev = to_platform_device(dev);
399         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
400         int ret;
401 
402         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
403                               WM831X_RTC_ALM_ENA, 0);
404         if (ret != 0)
405                 dev_err(&pdev->dev, "Failed to stop RTC alarm: %d\n", ret);
406 
407         return 0;
408 }
409 #else
410 #define wm831x_rtc_suspend NULL
411 #define wm831x_rtc_resume NULL
412 #define wm831x_rtc_freeze NULL
413 #endif
414 
415 static int wm831x_rtc_probe(struct platform_device *pdev)
416 {
417         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
418         struct wm831x_rtc *wm831x_rtc;
419         int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));
420         int ret = 0;
421 
422         wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);
423         if (wm831x_rtc == NULL)
424                 return -ENOMEM;
425 
426         platform_set_drvdata(pdev, wm831x_rtc);
427         wm831x_rtc->wm831x = wm831x;
428 
429         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
430         if (ret < 0) {
431                 dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
432                 goto err;
433         }
434         if (ret & WM831X_RTC_ALM_ENA)
435                 wm831x_rtc->alarm_enabled = 1;
436 
437         device_init_wakeup(&pdev->dev, 1);
438 
439         wm831x_rtc->rtc = devm_rtc_device_register(&pdev->dev, "wm831x",
440                                               &wm831x_rtc_ops, THIS_MODULE);
441         if (IS_ERR(wm831x_rtc->rtc)) {
442                 ret = PTR_ERR(wm831x_rtc->rtc);
443                 goto err;
444         }
445 
446         ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL,
447                                 wm831x_alm_irq,
448                                 IRQF_TRIGGER_RISING, "RTC alarm",
449                                 wm831x_rtc);
450         if (ret != 0) {
451                 dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
452                         alm_irq, ret);
453         }
454 
455         wm831x_rtc_add_randomness(wm831x);
456 
457         return 0;
458 
459 err:
460         return ret;
461 }
462 
463 static const struct dev_pm_ops wm831x_rtc_pm_ops = {
464         .suspend = wm831x_rtc_suspend,
465         .resume = wm831x_rtc_resume,
466 
467         .freeze = wm831x_rtc_freeze,
468         .thaw = wm831x_rtc_resume,
469         .restore = wm831x_rtc_resume,
470 
471         .poweroff = wm831x_rtc_suspend,
472 };
473 
474 static struct platform_driver wm831x_rtc_driver = {
475         .probe = wm831x_rtc_probe,
476         .driver = {
477                 .name = "wm831x-rtc",
478                 .pm = &wm831x_rtc_pm_ops,
479         },
480 };
481 
482 module_platform_driver(wm831x_rtc_driver);
483 
484 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
485 MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
486 MODULE_LICENSE("GPL");
487 MODULE_ALIAS("platform:wm831x-rtc");
488 

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