1 /*
2 * An RTC driver for the NVIDIA Tegra 200 series internal RTC.
3 *
4 * Copyright (c) 2010, NVIDIA Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * more details.
15 *
16 * You should have received a copy of the GNU General Public License along
17 * with this program; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/slab.h>
24 #include <linux/irq.h>
25 #include <linux/io.h>
26 #include <linux/delay.h>
27 #include <linux/rtc.h>
28 #include <linux/platform_device.h>
29
30 /* set to 1 = busy every eight 32kHz clocks during copy of sec+msec to AHB */
31 #define TEGRA_RTC_REG_BUSY 0x004
32 #define TEGRA_RTC_REG_SECONDS 0x008
33 /* when msec is read, the seconds are buffered into shadow seconds. */
34 #define TEGRA_RTC_REG_SHADOW_SECONDS 0x00c
35 #define TEGRA_RTC_REG_MILLI_SECONDS 0x010
36 #define TEGRA_RTC_REG_SECONDS_ALARM0 0x014
37 #define TEGRA_RTC_REG_SECONDS_ALARM1 0x018
38 #define TEGRA_RTC_REG_MILLI_SECONDS_ALARM0 0x01c
39 #define TEGRA_RTC_REG_INTR_MASK 0x028
40 /* write 1 bits to clear status bits */
41 #define TEGRA_RTC_REG_INTR_STATUS 0x02c
42
43 /* bits in INTR_MASK */
44 #define TEGRA_RTC_INTR_MASK_MSEC_CDN_ALARM (1<<4)
45 #define TEGRA_RTC_INTR_MASK_SEC_CDN_ALARM (1<<3)
46 #define TEGRA_RTC_INTR_MASK_MSEC_ALARM (1<<2)
47 #define TEGRA_RTC_INTR_MASK_SEC_ALARM1 (1<<1)
48 #define TEGRA_RTC_INTR_MASK_SEC_ALARM0 (1<<0)
49
50 /* bits in INTR_STATUS */
51 #define TEGRA_RTC_INTR_STATUS_MSEC_CDN_ALARM (1<<4)
52 #define TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM (1<<3)
53 #define TEGRA_RTC_INTR_STATUS_MSEC_ALARM (1<<2)
54 #define TEGRA_RTC_INTR_STATUS_SEC_ALARM1 (1<<1)
55 #define TEGRA_RTC_INTR_STATUS_SEC_ALARM0 (1<<0)
56
57 struct tegra_rtc_info {
58 struct platform_device *pdev;
59 struct rtc_device *rtc_dev;
60 void __iomem *rtc_base; /* NULL if not initialized. */
61 int tegra_rtc_irq; /* alarm and periodic irq */
62 spinlock_t tegra_rtc_lock;
63 };
64
65 /* RTC hardware is busy when it is updating its values over AHB once
66 * every eight 32kHz clocks (~250uS).
67 * outside of these updates the CPU is free to write.
68 * CPU is always free to read.
69 */
tegra_rtc_check_busy(struct tegra_rtc_info * info)70 static inline u32 tegra_rtc_check_busy(struct tegra_rtc_info *info)
71 {
72 return readl(info->rtc_base + TEGRA_RTC_REG_BUSY) & 1;
73 }
74
75 /* Wait for hardware to be ready for writing.
76 * This function tries to maximize the amount of time before the next update.
77 * It does this by waiting for the RTC to become busy with its periodic update,
78 * then returning once the RTC first becomes not busy.
79 * This periodic update (where the seconds and milliseconds are copied to the
80 * AHB side) occurs every eight 32kHz clocks (~250uS).
81 * The behavior of this function allows us to make some assumptions without
82 * introducing a race, because 250uS is plenty of time to read/write a value.
83 */
tegra_rtc_wait_while_busy(struct device * dev)84 static int tegra_rtc_wait_while_busy(struct device *dev)
85 {
86 struct tegra_rtc_info *info = dev_get_drvdata(dev);
87
88 int retries = 500; /* ~490 us is the worst case, ~250 us is best. */
89
90 /* first wait for the RTC to become busy. this is when it
91 * posts its updated seconds+msec registers to AHB side. */
92 while (tegra_rtc_check_busy(info)) {
93 if (!retries--)
94 goto retry_failed;
95 udelay(1);
96 }
97
98 /* now we have about 250 us to manipulate registers */
99 return 0;
100
101 retry_failed:
102 dev_err(dev, "write failed:retry count exceeded.\n");
103 return -ETIMEDOUT;
104 }
105
tegra_rtc_read_time(struct device * dev,struct rtc_time * tm)106 static int tegra_rtc_read_time(struct device *dev, struct rtc_time *tm)
107 {
108 struct tegra_rtc_info *info = dev_get_drvdata(dev);
109 unsigned long sec, msec;
110 unsigned long sl_irq_flags;
111
112 /* RTC hardware copies seconds to shadow seconds when a read
113 * of milliseconds occurs. use a lock to keep other threads out. */
114 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
115
116 msec = readl(info->rtc_base + TEGRA_RTC_REG_MILLI_SECONDS);
117 sec = readl(info->rtc_base + TEGRA_RTC_REG_SHADOW_SECONDS);
118
119 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
120
121 rtc_time_to_tm(sec, tm);
122
123 dev_vdbg(dev, "time read as %lu. %d/%d/%d %d:%02u:%02u\n",
124 sec,
125 tm->tm_mon + 1,
126 tm->tm_mday,
127 tm->tm_year + 1900,
128 tm->tm_hour,
129 tm->tm_min,
130 tm->tm_sec
131 );
132
133 return 0;
134 }
135
tegra_rtc_set_time(struct device * dev,struct rtc_time * tm)136 static int tegra_rtc_set_time(struct device *dev, struct rtc_time *tm)
137 {
138 struct tegra_rtc_info *info = dev_get_drvdata(dev);
139 unsigned long sec;
140 int ret;
141
142 /* convert tm to seconds. */
143 ret = rtc_valid_tm(tm);
144 if (ret)
145 return ret;
146
147 rtc_tm_to_time(tm, &sec);
148
149 dev_vdbg(dev, "time set to %lu. %d/%d/%d %d:%02u:%02u\n",
150 sec,
151 tm->tm_mon+1,
152 tm->tm_mday,
153 tm->tm_year+1900,
154 tm->tm_hour,
155 tm->tm_min,
156 tm->tm_sec
157 );
158
159 /* seconds only written if wait succeeded. */
160 ret = tegra_rtc_wait_while_busy(dev);
161 if (!ret)
162 writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS);
163
164 dev_vdbg(dev, "time read back as %d\n",
165 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS));
166
167 return ret;
168 }
169
tegra_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)170 static int tegra_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
171 {
172 struct tegra_rtc_info *info = dev_get_drvdata(dev);
173 unsigned long sec;
174 unsigned tmp;
175
176 sec = readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
177
178 if (sec == 0) {
179 /* alarm is disabled. */
180 alarm->enabled = 0;
181 alarm->time.tm_mon = -1;
182 alarm->time.tm_mday = -1;
183 alarm->time.tm_year = -1;
184 alarm->time.tm_hour = -1;
185 alarm->time.tm_min = -1;
186 alarm->time.tm_sec = -1;
187 } else {
188 /* alarm is enabled. */
189 alarm->enabled = 1;
190 rtc_time_to_tm(sec, &alarm->time);
191 }
192
193 tmp = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
194 alarm->pending = (tmp & TEGRA_RTC_INTR_STATUS_SEC_ALARM0) != 0;
195
196 return 0;
197 }
198
tegra_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)199 static int tegra_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
200 {
201 struct tegra_rtc_info *info = dev_get_drvdata(dev);
202 unsigned status;
203 unsigned long sl_irq_flags;
204
205 tegra_rtc_wait_while_busy(dev);
206 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
207
208 /* read the original value, and OR in the flag. */
209 status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
210 if (enabled)
211 status |= TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* set it */
212 else
213 status &= ~TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* clear it */
214
215 writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
216
217 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
218
219 return 0;
220 }
221
tegra_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)222 static int tegra_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
223 {
224 struct tegra_rtc_info *info = dev_get_drvdata(dev);
225 unsigned long sec;
226
227 if (alarm->enabled)
228 rtc_tm_to_time(&alarm->time, &sec);
229 else
230 sec = 0;
231
232 tegra_rtc_wait_while_busy(dev);
233 writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
234 dev_vdbg(dev, "alarm read back as %d\n",
235 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
236
237 /* if successfully written and alarm is enabled ... */
238 if (sec) {
239 tegra_rtc_alarm_irq_enable(dev, 1);
240
241 dev_vdbg(dev, "alarm set as %lu. %d/%d/%d %d:%02u:%02u\n",
242 sec,
243 alarm->time.tm_mon+1,
244 alarm->time.tm_mday,
245 alarm->time.tm_year+1900,
246 alarm->time.tm_hour,
247 alarm->time.tm_min,
248 alarm->time.tm_sec);
249 } else {
250 /* disable alarm if 0 or write error. */
251 dev_vdbg(dev, "alarm disabled\n");
252 tegra_rtc_alarm_irq_enable(dev, 0);
253 }
254
255 return 0;
256 }
257
tegra_rtc_proc(struct device * dev,struct seq_file * seq)258 static int tegra_rtc_proc(struct device *dev, struct seq_file *seq)
259 {
260 if (!dev || !dev->driver)
261 return 0;
262
263 return seq_printf(seq, "name\t\t: %s\n", dev_name(dev));
264 }
265
tegra_rtc_irq_handler(int irq,void * data)266 static irqreturn_t tegra_rtc_irq_handler(int irq, void *data)
267 {
268 struct device *dev = data;
269 struct tegra_rtc_info *info = dev_get_drvdata(dev);
270 unsigned long events = 0;
271 unsigned status;
272 unsigned long sl_irq_flags;
273
274 status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
275 if (status) {
276 /* clear the interrupt masks and status on any irq. */
277 tegra_rtc_wait_while_busy(dev);
278 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
279 writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
280 writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
281 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
282 }
283
284 /* check if Alarm */
285 if ((status & TEGRA_RTC_INTR_STATUS_SEC_ALARM0))
286 events |= RTC_IRQF | RTC_AF;
287
288 /* check if Periodic */
289 if ((status & TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM))
290 events |= RTC_IRQF | RTC_PF;
291
292 rtc_update_irq(info->rtc_dev, 1, events);
293
294 return IRQ_HANDLED;
295 }
296
297 static struct rtc_class_ops tegra_rtc_ops = {
298 .read_time = tegra_rtc_read_time,
299 .set_time = tegra_rtc_set_time,
300 .read_alarm = tegra_rtc_read_alarm,
301 .set_alarm = tegra_rtc_set_alarm,
302 .proc = tegra_rtc_proc,
303 .alarm_irq_enable = tegra_rtc_alarm_irq_enable,
304 };
305
tegra_rtc_probe(struct platform_device * pdev)306 static int __devinit tegra_rtc_probe(struct platform_device *pdev)
307 {
308 struct tegra_rtc_info *info;
309 struct resource *res;
310 int ret;
311
312 info = kzalloc(sizeof(struct tegra_rtc_info), GFP_KERNEL);
313 if (!info)
314 return -ENOMEM;
315
316 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
317 if (!res) {
318 dev_err(&pdev->dev,
319 "Unable to allocate resources for device.\n");
320 ret = -EBUSY;
321 goto err_free_info;
322 }
323
324 if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
325 dev_err(&pdev->dev,
326 "Unable to request mem region for device.\n");
327 ret = -EBUSY;
328 goto err_free_info;
329 }
330
331 info->tegra_rtc_irq = platform_get_irq(pdev, 0);
332 if (info->tegra_rtc_irq <= 0) {
333 ret = -EBUSY;
334 goto err_release_mem_region;
335 }
336
337 info->rtc_base = ioremap_nocache(res->start, resource_size(res));
338 if (!info->rtc_base) {
339 dev_err(&pdev->dev, "Unable to grab IOs for device.\n");
340 ret = -EBUSY;
341 goto err_release_mem_region;
342 }
343
344 /* set context info. */
345 info->pdev = pdev;
346 spin_lock_init(&info->tegra_rtc_lock);
347
348 platform_set_drvdata(pdev, info);
349
350 /* clear out the hardware. */
351 writel(0, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
352 writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
353 writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
354
355 device_init_wakeup(&pdev->dev, 1);
356
357 info->rtc_dev = rtc_device_register(
358 pdev->name, &pdev->dev, &tegra_rtc_ops, THIS_MODULE);
359 if (IS_ERR(info->rtc_dev)) {
360 ret = PTR_ERR(info->rtc_dev);
361 info->rtc_dev = NULL;
362 dev_err(&pdev->dev,
363 "Unable to register device (err=%d).\n",
364 ret);
365 goto err_iounmap;
366 }
367
368 ret = request_irq(info->tegra_rtc_irq, tegra_rtc_irq_handler,
369 IRQF_TRIGGER_HIGH, "rtc alarm", &pdev->dev);
370 if (ret) {
371 dev_err(&pdev->dev,
372 "Unable to request interrupt for device (err=%d).\n",
373 ret);
374 goto err_dev_unreg;
375 }
376
377 dev_notice(&pdev->dev, "Tegra internal Real Time Clock\n");
378
379 return 0;
380
381 err_dev_unreg:
382 rtc_device_unregister(info->rtc_dev);
383 err_iounmap:
384 iounmap(info->rtc_base);
385 err_release_mem_region:
386 release_mem_region(res->start, resource_size(res));
387 err_free_info:
388 kfree(info);
389
390 return ret;
391 }
392
tegra_rtc_remove(struct platform_device * pdev)393 static int __devexit tegra_rtc_remove(struct platform_device *pdev)
394 {
395 struct tegra_rtc_info *info = platform_get_drvdata(pdev);
396 struct resource *res;
397
398 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
399 if (!res)
400 return -EBUSY;
401
402 free_irq(info->tegra_rtc_irq, &pdev->dev);
403 rtc_device_unregister(info->rtc_dev);
404 iounmap(info->rtc_base);
405 release_mem_region(res->start, resource_size(res));
406 kfree(info);
407
408 platform_set_drvdata(pdev, NULL);
409
410 return 0;
411 }
412
413 #ifdef CONFIG_PM
tegra_rtc_suspend(struct platform_device * pdev,pm_message_t state)414 static int tegra_rtc_suspend(struct platform_device *pdev, pm_message_t state)
415 {
416 struct device *dev = &pdev->dev;
417 struct tegra_rtc_info *info = platform_get_drvdata(pdev);
418
419 tegra_rtc_wait_while_busy(dev);
420
421 /* only use ALARM0 as a wake source. */
422 writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
423 writel(TEGRA_RTC_INTR_STATUS_SEC_ALARM0,
424 info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
425
426 dev_vdbg(dev, "alarm sec = %d\n",
427 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
428
429 dev_vdbg(dev, "Suspend (device_may_wakeup=%d) irq:%d\n",
430 device_may_wakeup(dev), info->tegra_rtc_irq);
431
432 /* leave the alarms on as a wake source. */
433 if (device_may_wakeup(dev))
434 enable_irq_wake(info->tegra_rtc_irq);
435
436 return 0;
437 }
438
tegra_rtc_resume(struct platform_device * pdev)439 static int tegra_rtc_resume(struct platform_device *pdev)
440 {
441 struct device *dev = &pdev->dev;
442 struct tegra_rtc_info *info = platform_get_drvdata(pdev);
443
444 dev_vdbg(dev, "Resume (device_may_wakeup=%d)\n",
445 device_may_wakeup(dev));
446 /* alarms were left on as a wake source, turn them off. */
447 if (device_may_wakeup(dev))
448 disable_irq_wake(info->tegra_rtc_irq);
449
450 return 0;
451 }
452 #endif
453
tegra_rtc_shutdown(struct platform_device * pdev)454 static void tegra_rtc_shutdown(struct platform_device *pdev)
455 {
456 dev_vdbg(&pdev->dev, "disabling interrupts.\n");
457 tegra_rtc_alarm_irq_enable(&pdev->dev, 0);
458 }
459
460 MODULE_ALIAS("platform:tegra_rtc");
461 static struct platform_driver tegra_rtc_driver = {
462 .remove = __devexit_p(tegra_rtc_remove),
463 .shutdown = tegra_rtc_shutdown,
464 .driver = {
465 .name = "tegra_rtc",
466 .owner = THIS_MODULE,
467 },
468 #ifdef CONFIG_PM
469 .suspend = tegra_rtc_suspend,
470 .resume = tegra_rtc_resume,
471 #endif
472 };
473
tegra_rtc_init(void)474 static int __init tegra_rtc_init(void)
475 {
476 return platform_driver_probe(&tegra_rtc_driver, tegra_rtc_probe);
477 }
478 module_init(tegra_rtc_init);
479
tegra_rtc_exit(void)480 static void __exit tegra_rtc_exit(void)
481 {
482 platform_driver_unregister(&tegra_rtc_driver);
483 }
484 module_exit(tegra_rtc_exit);
485
486 MODULE_AUTHOR("Jon Mayo <jmayo@nvidia.com>");
487 MODULE_DESCRIPTION("driver for Tegra internal RTC");
488 MODULE_LICENSE("GPL");
489