rtc-wm831x.c revision bc862f44cb49f401b05d7fc2a400209c97535a28 
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
93struct wm831x_rtc {
94	struct wm831x *wm831x;
95	struct rtc_device *rtc;
96	unsigned int alarm_enabled:1;
97};
98
99static 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 */
122static 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 */
172static 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 */
236static 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
268static 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
276static 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
284static 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
327static 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
338static 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
347static 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. */
357static 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 */
379static 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 */
396static 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
415static 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
459err:
460	return ret;
461}
462
463static int wm831x_rtc_remove(struct platform_device *pdev)
464{
465	return 0;
466}
467
468static const struct dev_pm_ops wm831x_rtc_pm_ops = {
469	.suspend = wm831x_rtc_suspend,
470	.resume = wm831x_rtc_resume,
471
472	.freeze = wm831x_rtc_freeze,
473	.thaw = wm831x_rtc_resume,
474	.restore = wm831x_rtc_resume,
475
476	.poweroff = wm831x_rtc_suspend,
477};
478
479static struct platform_driver wm831x_rtc_driver = {
480	.probe = wm831x_rtc_probe,
481	.remove = wm831x_rtc_remove,
482	.driver = {
483		.name = "wm831x-rtc",
484		.pm = &wm831x_rtc_pm_ops,
485	},
486};
487
488module_platform_driver(wm831x_rtc_driver);
489
490MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
491MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
492MODULE_LICENSE("GPL");
493MODULE_ALIAS("platform:wm831x-rtc");
494