rtc-wm831x.c revision 2d65943e55bdd538640d0908bc9f3ead138b0431 
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
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
99/*
100 * Read current time and date in RTC
101 */
102static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
103{
104	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
105	struct wm831x *wm831x = wm831x_rtc->wm831x;
106	u16 time1[2], time2[2];
107	int ret;
108	int count = 0;
109
110	/* Has the RTC been programmed? */
111	ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
112	if (ret < 0) {
113		dev_err(dev, "Failed to read RTC control: %d\n", ret);
114		return ret;
115	}
116	if (!(ret & WM831X_RTC_VALID)) {
117		dev_dbg(dev, "RTC not yet configured\n");
118		return -EINVAL;
119	}
120
121	/* Read twice to make sure we don't read a corrupt, partially
122	 * incremented, value.
123	 */
124	do {
125		ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
126				       2, time1);
127		if (ret != 0)
128			continue;
129
130		ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
131				       2, time2);
132		if (ret != 0)
133			continue;
134
135		if (memcmp(time1, time2, sizeof(time1)) == 0) {
136			u32 time = (time1[0] << 16) | time1[1];
137
138			rtc_time_to_tm(time, tm);
139			return rtc_valid_tm(tm);
140		}
141
142	} while (++count < WM831X_GET_TIME_RETRIES);
143
144	dev_err(dev, "Timed out reading current time\n");
145
146	return -EIO;
147}
148
149/*
150 * Set current time and date in RTC
151 */
152static int wm831x_rtc_set_mmss(struct device *dev, unsigned long time)
153{
154	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
155	struct wm831x *wm831x = wm831x_rtc->wm831x;
156	struct rtc_time new_tm;
157	unsigned long new_time;
158	int ret;
159	int count = 0;
160
161	ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
162			       (time >> 16) & 0xffff);
163	if (ret < 0) {
164		dev_err(dev, "Failed to write TIME_1: %d\n", ret);
165		return ret;
166	}
167
168	ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
169	if (ret < 0) {
170		dev_err(dev, "Failed to write TIME_2: %d\n", ret);
171		return ret;
172	}
173
174	/* Wait for the update to complete - should happen first time
175	 * round but be conservative.
176	 */
177	do {
178		msleep(1);
179
180		ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
181		if (ret < 0)
182			ret = WM831X_RTC_SYNC_BUSY;
183	} while (!(ret & WM831X_RTC_SYNC_BUSY) &&
184		 ++count < WM831X_SET_TIME_RETRIES);
185
186	if (ret & WM831X_RTC_SYNC_BUSY) {
187		dev_err(dev, "Timed out writing RTC update\n");
188		return -EIO;
189	}
190
191	/* Check that the update was accepted; security features may
192	 * have caused the update to be ignored.
193	 */
194	ret = wm831x_rtc_readtime(dev, &new_tm);
195	if (ret < 0)
196		return ret;
197
198	ret = rtc_tm_to_time(&new_tm, &new_time);
199	if (ret < 0) {
200		dev_err(dev, "Failed to convert time: %d\n", ret);
201		return ret;
202	}
203
204	/* Allow a second of change in case of tick */
205	if (new_time - time > 1) {
206		dev_err(dev, "RTC update not permitted by hardware\n");
207		return -EPERM;
208	}
209
210	return 0;
211}
212
213/*
214 * Read alarm time and date in RTC
215 */
216static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
217{
218	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
219	int ret;
220	u16 data[2];
221	u32 time;
222
223	ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
224			       2, data);
225	if (ret != 0) {
226		dev_err(dev, "Failed to read alarm time: %d\n", ret);
227		return ret;
228	}
229
230	time = (data[0] << 16) | data[1];
231
232	rtc_time_to_tm(time, &alrm->time);
233
234	ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
235	if (ret < 0) {
236		dev_err(dev, "Failed to read RTC control: %d\n", ret);
237		return ret;
238	}
239
240	if (ret & WM831X_RTC_ALM_ENA)
241		alrm->enabled = 1;
242	else
243		alrm->enabled = 0;
244
245	return 0;
246}
247
248static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
249{
250	wm831x_rtc->alarm_enabled = 0;
251
252	return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
253			       WM831X_RTC_ALM_ENA, 0);
254}
255
256static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
257{
258	wm831x_rtc->alarm_enabled = 1;
259
260	return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
261			       WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
262}
263
264static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
265{
266	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
267	struct wm831x *wm831x = wm831x_rtc->wm831x;
268	int ret;
269	unsigned long time;
270
271	ret = rtc_tm_to_time(&alrm->time, &time);
272	if (ret < 0) {
273		dev_err(dev, "Failed to convert time: %d\n", ret);
274		return ret;
275	}
276
277	ret = wm831x_rtc_stop_alarm(wm831x_rtc);
278	if (ret < 0) {
279		dev_err(dev, "Failed to stop alarm: %d\n", ret);
280		return ret;
281	}
282
283	ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
284			       (time >> 16) & 0xffff);
285	if (ret < 0) {
286		dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
287		return ret;
288	}
289
290	ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
291	if (ret < 0) {
292		dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
293		return ret;
294	}
295
296	if (alrm->enabled) {
297		ret = wm831x_rtc_start_alarm(wm831x_rtc);
298		if (ret < 0) {
299			dev_err(dev, "Failed to start alarm: %d\n", ret);
300			return ret;
301		}
302	}
303
304	return 0;
305}
306
307static int wm831x_rtc_alarm_irq_enable(struct device *dev,
308				       unsigned int enabled)
309{
310	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
311
312	if (enabled)
313		return wm831x_rtc_start_alarm(wm831x_rtc);
314	else
315		return wm831x_rtc_stop_alarm(wm831x_rtc);
316}
317
318static irqreturn_t wm831x_alm_irq(int irq, void *data)
319{
320	struct wm831x_rtc *wm831x_rtc = data;
321
322	rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
323
324	return IRQ_HANDLED;
325}
326
327static const struct rtc_class_ops wm831x_rtc_ops = {
328	.read_time = wm831x_rtc_readtime,
329	.set_mmss = wm831x_rtc_set_mmss,
330	.read_alarm = wm831x_rtc_readalarm,
331	.set_alarm = wm831x_rtc_setalarm,
332	.alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
333};
334
335#ifdef CONFIG_PM
336/* Turn off the alarm if it should not be a wake source. */
337static int wm831x_rtc_suspend(struct device *dev)
338{
339	struct platform_device *pdev = to_platform_device(dev);
340	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
341	int ret, enable;
342
343	if (wm831x_rtc->alarm_enabled && device_may_wakeup(&pdev->dev))
344		enable = WM831X_RTC_ALM_ENA;
345	else
346		enable = 0;
347
348	ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
349			      WM831X_RTC_ALM_ENA, enable);
350	if (ret != 0)
351		dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret);
352
353	return 0;
354}
355
356/* Enable the alarm if it should be enabled (in case it was disabled to
357 * prevent use as a wake source).
358 */
359static int wm831x_rtc_resume(struct device *dev)
360{
361	struct platform_device *pdev = to_platform_device(dev);
362	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
363	int ret;
364
365	if (wm831x_rtc->alarm_enabled) {
366		ret = wm831x_rtc_start_alarm(wm831x_rtc);
367		if (ret != 0)
368			dev_err(&pdev->dev,
369				"Failed to restart RTC alarm: %d\n", ret);
370	}
371
372	return 0;
373}
374
375/* Unconditionally disable the alarm */
376static int wm831x_rtc_freeze(struct device *dev)
377{
378	struct platform_device *pdev = to_platform_device(dev);
379	struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
380	int ret;
381
382	ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
383			      WM831X_RTC_ALM_ENA, 0);
384	if (ret != 0)
385		dev_err(&pdev->dev, "Failed to stop RTC alarm: %d\n", ret);
386
387	return 0;
388}
389#else
390#define wm831x_rtc_suspend NULL
391#define wm831x_rtc_resume NULL
392#define wm831x_rtc_freeze NULL
393#endif
394
395static int wm831x_rtc_probe(struct platform_device *pdev)
396{
397	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
398	struct wm831x_rtc *wm831x_rtc;
399	int alm_irq = platform_get_irq_byname(pdev, "ALM");
400	int ret = 0;
401
402	wm831x_rtc = kzalloc(sizeof(*wm831x_rtc), GFP_KERNEL);
403	if (wm831x_rtc == NULL)
404		return -ENOMEM;
405
406	platform_set_drvdata(pdev, wm831x_rtc);
407	wm831x_rtc->wm831x = wm831x;
408
409	ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
410	if (ret < 0) {
411		dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
412		goto err;
413	}
414	if (ret & WM831X_RTC_ALM_ENA)
415		wm831x_rtc->alarm_enabled = 1;
416
417	device_init_wakeup(&pdev->dev, 1);
418
419	wm831x_rtc->rtc = rtc_device_register("wm831x", &pdev->dev,
420					      &wm831x_rtc_ops, THIS_MODULE);
421	if (IS_ERR(wm831x_rtc->rtc)) {
422		ret = PTR_ERR(wm831x_rtc->rtc);
423		goto err;
424	}
425
426	ret = request_threaded_irq(alm_irq, NULL, wm831x_alm_irq,
427				   IRQF_TRIGGER_RISING, "RTC alarm",
428				   wm831x_rtc);
429	if (ret != 0) {
430		dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
431			alm_irq, ret);
432	}
433
434	return 0;
435
436err:
437	kfree(wm831x_rtc);
438	return ret;
439}
440
441static int __devexit wm831x_rtc_remove(struct platform_device *pdev)
442{
443	struct wm831x_rtc *wm831x_rtc = platform_get_drvdata(pdev);
444	int alm_irq = platform_get_irq_byname(pdev, "ALM");
445
446	free_irq(alm_irq, wm831x_rtc);
447	rtc_device_unregister(wm831x_rtc->rtc);
448	kfree(wm831x_rtc);
449
450	return 0;
451}
452
453static const struct dev_pm_ops wm831x_rtc_pm_ops = {
454	.suspend = wm831x_rtc_suspend,
455	.resume = wm831x_rtc_resume,
456
457	.freeze = wm831x_rtc_freeze,
458	.thaw = wm831x_rtc_resume,
459	.restore = wm831x_rtc_resume,
460
461	.poweroff = wm831x_rtc_suspend,
462};
463
464static struct platform_driver wm831x_rtc_driver = {
465	.probe = wm831x_rtc_probe,
466	.remove = __devexit_p(wm831x_rtc_remove),
467	.driver = {
468		.name = "wm831x-rtc",
469		.pm = &wm831x_rtc_pm_ops,
470	},
471};
472
473static int __init wm831x_rtc_init(void)
474{
475	return platform_driver_register(&wm831x_rtc_driver);
476}
477module_init(wm831x_rtc_init);
478
479static void __exit wm831x_rtc_exit(void)
480{
481	platform_driver_unregister(&wm831x_rtc_driver);
482}
483module_exit(wm831x_rtc_exit);
484
485MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
486MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
487MODULE_LICENSE("GPL");
488MODULE_ALIAS("platform:wm831x-rtc");
489