blob: 1aa709dda0d67d0fbb9e5d660211e207b22ca3ba [file] [log] [blame]
Wu, Bryan8cc75c92007-05-06 14:50:32 -07001/*
2 * Blackfin On-Chip Real Time Clock Driver
Mike Frysinger2c95cd72007-07-15 02:33:26 +08003 * Supports BF53[123]/BF53[467]/BF54[2489]
Wu, Bryan8cc75c92007-05-06 14:50:32 -07004 *
5 * Copyright 2004-2007 Analog Devices Inc.
6 *
7 * Enter bugs at http://blackfin.uclinux.org/
8 *
9 * Licensed under the GPL-2 or later.
10 */
11
12/* The biggest issue we deal with in this driver is that register writes are
13 * synced to the RTC frequency of 1Hz. So if you write to a register and
14 * attempt to write again before the first write has completed, the new write
15 * is simply discarded. This can easily be troublesome if userspace disables
16 * one event (say periodic) and then right after enables an event (say alarm).
17 * Since all events are maintained in the same interrupt mask register, if
18 * we wrote to it to disable the first event and then wrote to it again to
19 * enable the second event, that second event would not be enabled as the
20 * write would be discarded and things quickly fall apart.
21 *
22 * To keep this delay from significantly degrading performance (we, in theory,
23 * would have to sleep for up to 1 second everytime we wanted to write a
24 * register), we only check the write pending status before we start to issue
25 * a new write. We bank on the idea that it doesnt matter when the sync
26 * happens so long as we don't attempt another write before it does. The only
27 * time userspace would take this penalty is when they try and do multiple
28 * operations right after another ... but in this case, they need to take the
29 * sync penalty, so we should be OK.
30 *
31 * Also note that the RTC_ISTAT register does not suffer this penalty; its
32 * writes to clear status registers complete immediately.
33 */
34
35#include <linux/module.h>
36#include <linux/kernel.h>
37#include <linux/bcd.h>
38#include <linux/rtc.h>
39#include <linux/init.h>
40#include <linux/platform_device.h>
41#include <linux/seq_file.h>
42#include <linux/interrupt.h>
43#include <linux/spinlock.h>
44#include <linux/delay.h>
45
46#include <asm/blackfin.h>
47
48#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __FUNCTION__, __LINE__, ## args)
49#define stampit() stamp("here i am")
50
51struct bfin_rtc {
52 struct rtc_device *rtc_dev;
53 struct rtc_time rtc_alarm;
54 spinlock_t lock;
55};
56
57/* Bit values for the ISTAT / ICTL registers */
58#define RTC_ISTAT_WRITE_COMPLETE 0x8000
59#define RTC_ISTAT_WRITE_PENDING 0x4000
60#define RTC_ISTAT_ALARM_DAY 0x0040
61#define RTC_ISTAT_24HR 0x0020
62#define RTC_ISTAT_HOUR 0x0010
63#define RTC_ISTAT_MIN 0x0008
64#define RTC_ISTAT_SEC 0x0004
65#define RTC_ISTAT_ALARM 0x0002
66#define RTC_ISTAT_STOPWATCH 0x0001
67
68/* Shift values for RTC_STAT register */
69#define DAY_BITS_OFF 17
70#define HOUR_BITS_OFF 12
71#define MIN_BITS_OFF 6
72#define SEC_BITS_OFF 0
73
74/* Some helper functions to convert between the common RTC notion of time
75 * and the internal Blackfin notion that is stored in 32bits.
76 */
77static inline u32 rtc_time_to_bfin(unsigned long now)
78{
79 u32 sec = (now % 60);
80 u32 min = (now % (60 * 60)) / 60;
81 u32 hour = (now % (60 * 60 * 24)) / (60 * 60);
82 u32 days = (now / (60 * 60 * 24));
83 return (sec << SEC_BITS_OFF) +
84 (min << MIN_BITS_OFF) +
85 (hour << HOUR_BITS_OFF) +
86 (days << DAY_BITS_OFF);
87}
88static inline unsigned long rtc_bfin_to_time(u32 rtc_bfin)
89{
90 return (((rtc_bfin >> SEC_BITS_OFF) & 0x003F)) +
91 (((rtc_bfin >> MIN_BITS_OFF) & 0x003F) * 60) +
92 (((rtc_bfin >> HOUR_BITS_OFF) & 0x001F) * 60 * 60) +
93 (((rtc_bfin >> DAY_BITS_OFF) & 0x7FFF) * 60 * 60 * 24);
94}
95static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm)
96{
97 rtc_time_to_tm(rtc_bfin_to_time(rtc_bfin), tm);
98}
99
100/* Wait for the previous write to a RTC register to complete.
101 * Unfortunately, we can't sleep here as that introduces a race condition when
102 * turning on interrupt events. Consider this:
103 * - process sets alarm
104 * - process enables alarm
105 * - process sleeps while waiting for rtc write to sync
106 * - interrupt fires while process is sleeping
107 * - interrupt acks the event by writing to ISTAT
108 * - interrupt sets the WRITE PENDING bit
109 * - interrupt handler finishes
110 * - process wakes up, sees WRITE PENDING bit set, goes to sleep
111 * - interrupt fires while process is sleeping
112 * If anyone can point out the obvious solution here, i'm listening :). This
113 * shouldn't be an issue on an SMP or preempt system as this function should
114 * only be called with the rtc lock held.
115 */
116static void rtc_bfin_sync_pending(void)
117{
118 stampit();
119 while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE)) {
120 if (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING))
121 break;
122 }
123 bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
124}
125
126static void rtc_bfin_reset(struct bfin_rtc *rtc)
127{
128 /* Initialize the RTC. Enable pre-scaler to scale RTC clock
129 * to 1Hz and clear interrupt/status registers. */
130 spin_lock_irq(&rtc->lock);
131 rtc_bfin_sync_pending();
132 bfin_write_RTC_PREN(0x1);
133 bfin_write_RTC_ICTL(0);
134 bfin_write_RTC_SWCNT(0);
135 bfin_write_RTC_ALARM(0);
136 bfin_write_RTC_ISTAT(0xFFFF);
137 spin_unlock_irq(&rtc->lock);
138}
139
140static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
141{
142 struct platform_device *pdev = to_platform_device(dev_id);
143 struct bfin_rtc *rtc = platform_get_drvdata(pdev);
144 unsigned long events = 0;
145 u16 rtc_istat;
146
147 stampit();
148
149 spin_lock_irq(&rtc->lock);
150
151 rtc_istat = bfin_read_RTC_ISTAT();
152
153 if (rtc_istat & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) {
154 bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY);
155 events |= RTC_AF | RTC_IRQF;
156 }
157
158 if (rtc_istat & RTC_ISTAT_STOPWATCH) {
159 bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
160 events |= RTC_PF | RTC_IRQF;
161 bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
162 }
163
164 if (rtc_istat & RTC_ISTAT_SEC) {
165 bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
166 events |= RTC_UF | RTC_IRQF;
167 }
168
169 rtc_update_irq(rtc->rtc_dev, 1, events);
170
171 spin_unlock_irq(&rtc->lock);
172
173 return IRQ_HANDLED;
174}
175
176static int bfin_rtc_open(struct device *dev)
177{
178 struct bfin_rtc *rtc = dev_get_drvdata(dev);
179 int ret;
180
181 stampit();
182
183 ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_DISABLED, "rtc-bfin", dev);
184 if (unlikely(ret)) {
185 dev_err(dev, "request RTC IRQ failed with %d\n", ret);
186 return ret;
187 }
188
189 rtc_bfin_reset(rtc);
190
191 return ret;
192}
193
194static void bfin_rtc_release(struct device *dev)
195{
196 struct bfin_rtc *rtc = dev_get_drvdata(dev);
197 stampit();
198 rtc_bfin_reset(rtc);
199 free_irq(IRQ_RTC, dev);
200}
201
202static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
203{
204 struct bfin_rtc *rtc = dev_get_drvdata(dev);
205
206 stampit();
207
208 switch (cmd) {
209 case RTC_PIE_ON:
210 stampit();
211 spin_lock_irq(&rtc->lock);
212 rtc_bfin_sync_pending();
213 bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
214 bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
215 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_STOPWATCH);
216 spin_unlock_irq(&rtc->lock);
217 return 0;
218 case RTC_PIE_OFF:
219 stampit();
220 spin_lock_irq(&rtc->lock);
221 rtc_bfin_sync_pending();
222 bfin_write_RTC_SWCNT(0);
223 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_STOPWATCH);
224 spin_unlock_irq(&rtc->lock);
225 return 0;
226
227 case RTC_UIE_ON:
228 stampit();
229 spin_lock_irq(&rtc->lock);
230 rtc_bfin_sync_pending();
231 bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
232 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_SEC);
233 spin_unlock_irq(&rtc->lock);
234 return 0;
235 case RTC_UIE_OFF:
236 stampit();
237 spin_lock_irq(&rtc->lock);
238 rtc_bfin_sync_pending();
239 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_SEC);
240 spin_unlock_irq(&rtc->lock);
241 return 0;
242
243 case RTC_AIE_ON: {
244 unsigned long rtc_alarm;
245 u16 which_alarm;
246 int ret = 0;
247
248 stampit();
249
250 spin_lock_irq(&rtc->lock);
251
252 rtc_bfin_sync_pending();
253 if (rtc->rtc_alarm.tm_yday == -1) {
254 struct rtc_time now;
255 rtc_bfin_to_tm(bfin_read_RTC_STAT(), &now);
256 now.tm_sec = rtc->rtc_alarm.tm_sec;
257 now.tm_min = rtc->rtc_alarm.tm_min;
258 now.tm_hour = rtc->rtc_alarm.tm_hour;
259 ret = rtc_tm_to_time(&now, &rtc_alarm);
260 which_alarm = RTC_ISTAT_ALARM;
261 } else {
262 ret = rtc_tm_to_time(&rtc->rtc_alarm, &rtc_alarm);
263 which_alarm = RTC_ISTAT_ALARM_DAY;
264 }
265 if (ret == 0) {
266 bfin_write_RTC_ISTAT(which_alarm);
267 bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm));
268 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | which_alarm);
269 }
270
271 spin_unlock_irq(&rtc->lock);
272
273 return ret;
274 }
275 case RTC_AIE_OFF:
276 stampit();
277 spin_lock_irq(&rtc->lock);
278 rtc_bfin_sync_pending();
279 bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY));
280 spin_unlock_irq(&rtc->lock);
281 return 0;
282 }
283
284 return -ENOIOCTLCMD;
285}
286
287static int bfin_rtc_read_time(struct device *dev, struct rtc_time *tm)
288{
289 struct bfin_rtc *rtc = dev_get_drvdata(dev);
290
291 stampit();
292
293 spin_lock_irq(&rtc->lock);
294 rtc_bfin_sync_pending();
295 rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm);
296 spin_unlock_irq(&rtc->lock);
297
298 return 0;
299}
300
301static int bfin_rtc_set_time(struct device *dev, struct rtc_time *tm)
302{
303 struct bfin_rtc *rtc = dev_get_drvdata(dev);
304 int ret;
305 unsigned long now;
306
307 stampit();
308
309 spin_lock_irq(&rtc->lock);
310
311 ret = rtc_tm_to_time(tm, &now);
312 if (ret == 0) {
313 rtc_bfin_sync_pending();
314 bfin_write_RTC_STAT(rtc_time_to_bfin(now));
315 }
316
317 spin_unlock_irq(&rtc->lock);
318
319 return ret;
320}
321
322static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
323{
324 struct bfin_rtc *rtc = dev_get_drvdata(dev);
325 stampit();
326 memcpy(&alrm->time, &rtc->rtc_alarm, sizeof(struct rtc_time));
327 alrm->pending = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY));
328 return 0;
329}
330
331static int bfin_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
332{
333 struct bfin_rtc *rtc = dev_get_drvdata(dev);
334 stampit();
335 memcpy(&rtc->rtc_alarm, &alrm->time, sizeof(struct rtc_time));
336 return 0;
337}
338
339static int bfin_rtc_proc(struct device *dev, struct seq_file *seq)
340{
341#define yesno(x) (x ? "yes" : "no")
342 u16 ictl = bfin_read_RTC_ICTL();
343 stampit();
344 seq_printf(seq, "alarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM));
345 seq_printf(seq, "wkalarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM_DAY));
346 seq_printf(seq, "seconds_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_SEC));
347 seq_printf(seq, "periodic_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_STOPWATCH));
348#ifdef DEBUG
349 seq_printf(seq, "RTC_STAT\t: 0x%08X\n", bfin_read_RTC_STAT());
350 seq_printf(seq, "RTC_ICTL\t: 0x%04X\n", bfin_read_RTC_ICTL());
351 seq_printf(seq, "RTC_ISTAT\t: 0x%04X\n", bfin_read_RTC_ISTAT());
352 seq_printf(seq, "RTC_SWCNT\t: 0x%04X\n", bfin_read_RTC_SWCNT());
353 seq_printf(seq, "RTC_ALARM\t: 0x%08X\n", bfin_read_RTC_ALARM());
354 seq_printf(seq, "RTC_PREN\t: 0x%04X\n", bfin_read_RTC_PREN());
355#endif
356 return 0;
357}
358
359static int bfin_irq_set_freq(struct device *dev, int freq)
360{
361 struct bfin_rtc *rtc = dev_get_drvdata(dev);
362 stampit();
363 rtc->rtc_dev->irq_freq = freq;
364 return 0;
365}
366
367static struct rtc_class_ops bfin_rtc_ops = {
368 .open = bfin_rtc_open,
369 .release = bfin_rtc_release,
370 .ioctl = bfin_rtc_ioctl,
371 .read_time = bfin_rtc_read_time,
372 .set_time = bfin_rtc_set_time,
373 .read_alarm = bfin_rtc_read_alarm,
374 .set_alarm = bfin_rtc_set_alarm,
375 .proc = bfin_rtc_proc,
376 .irq_set_freq = bfin_irq_set_freq,
377};
378
379static int __devinit bfin_rtc_probe(struct platform_device *pdev)
380{
381 struct bfin_rtc *rtc;
382 int ret = 0;
383
384 stampit();
385
386 rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
387 if (unlikely(!rtc))
388 return -ENOMEM;
389
390 spin_lock_init(&rtc->lock);
391
392 rtc->rtc_dev = rtc_device_register(pdev->name, &pdev->dev, &bfin_rtc_ops, THIS_MODULE);
393 if (unlikely(IS_ERR(rtc))) {
394 ret = PTR_ERR(rtc->rtc_dev);
395 goto err;
396 }
397 rtc->rtc_dev->irq_freq = 0;
398 rtc->rtc_dev->max_user_freq = (2 << 16); /* stopwatch is an unsigned 16 bit reg */
399
400 platform_set_drvdata(pdev, rtc);
401
402 return 0;
403
404err:
405 kfree(rtc);
406 return ret;
407}
408
409static int __devexit bfin_rtc_remove(struct platform_device *pdev)
410{
411 struct bfin_rtc *rtc = platform_get_drvdata(pdev);
412
413 rtc_device_unregister(rtc->rtc_dev);
414 platform_set_drvdata(pdev, NULL);
415 kfree(rtc);
416
417 return 0;
418}
419
420static struct platform_driver bfin_rtc_driver = {
421 .driver = {
422 .name = "rtc-bfin",
423 .owner = THIS_MODULE,
424 },
425 .probe = bfin_rtc_probe,
426 .remove = __devexit_p(bfin_rtc_remove),
427};
428
429static int __init bfin_rtc_init(void)
430{
431 stampit();
432 return platform_driver_register(&bfin_rtc_driver);
433}
434
435static void __exit bfin_rtc_exit(void)
436{
437 platform_driver_unregister(&bfin_rtc_driver);
438}
439
440module_init(bfin_rtc_init);
441module_exit(bfin_rtc_exit);
442
443MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver");
444MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
445MODULE_LICENSE("GPL");