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8cc75c9a WB |
1 | /* |
2 | * Blackfin On-Chip Real Time Clock Driver | |
3 | * Supports BF531/BF532/BF533/BF534/BF536/BF537 | |
4 | * | |
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 | ||
51 | struct 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 | */ | |
77 | static 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 | } | |
88 | static 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 | } | |
95 | static 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 | */ | |
116 | static 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 | ||
126 | static 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 | ||
140 | static 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 | ||
176 | static 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 | ||
194 | static 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 | ||
202 | static 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 | ||
287 | static 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 | ||
301 | static 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 | ||
322 | static 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 | ||
331 | static 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 | ||
339 | static 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 | ||
359 | static 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 | ||
367 | static 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 | ||
379 | static 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 | ||
404 | err: | |
405 | kfree(rtc); | |
406 | return ret; | |
407 | } | |
408 | ||
409 | static 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 | ||
420 | static 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 | ||
429 | static int __init bfin_rtc_init(void) | |
430 | { | |
431 | stampit(); | |
432 | return platform_driver_register(&bfin_rtc_driver); | |
433 | } | |
434 | ||
435 | static void __exit bfin_rtc_exit(void) | |
436 | { | |
437 | platform_driver_unregister(&bfin_rtc_driver); | |
438 | } | |
439 | ||
440 | module_init(bfin_rtc_init); | |
441 | module_exit(bfin_rtc_exit); | |
442 | ||
443 | MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver"); | |
444 | MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); | |
445 | MODULE_LICENSE("GPL"); |