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/clk.h>
22 #include <linux/init.h>
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/irq.h>
26 #include <linux/io.h>
27 #include <linux/delay.h>
28 #include <linux/rtc.h>
29 #include <linux/platform_device.h>
30 #include <linux/pm.h>
31
32 /* set to 1 = busy every eight 32kHz clocks during copy of sec+msec to AHB */
33 #define TEGRA_RTC_REG_BUSY 0x004
34 #define TEGRA_RTC_REG_SECONDS 0x008
35 /* when msec is read, the seconds are buffered into shadow seconds. */
36 #define TEGRA_RTC_REG_SHADOW_SECONDS 0x00c
37 #define TEGRA_RTC_REG_MILLI_SECONDS 0x010
38 #define TEGRA_RTC_REG_SECONDS_ALARM0 0x014
39 #define TEGRA_RTC_REG_SECONDS_ALARM1 0x018
40 #define TEGRA_RTC_REG_MILLI_SECONDS_ALARM0 0x01c
41 #define TEGRA_RTC_REG_INTR_MASK 0x028
42 /* write 1 bits to clear status bits */
43 #define TEGRA_RTC_REG_INTR_STATUS 0x02c
44
45 /* bits in INTR_MASK */
46 #define TEGRA_RTC_INTR_MASK_MSEC_CDN_ALARM (1<<4)
47 #define TEGRA_RTC_INTR_MASK_SEC_CDN_ALARM (1<<3)
48 #define TEGRA_RTC_INTR_MASK_MSEC_ALARM (1<<2)
49 #define TEGRA_RTC_INTR_MASK_SEC_ALARM1 (1<<1)
50 #define TEGRA_RTC_INTR_MASK_SEC_ALARM0 (1<<0)
51
52 /* bits in INTR_STATUS */
53 #define TEGRA_RTC_INTR_STATUS_MSEC_CDN_ALARM (1<<4)
54 #define TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM (1<<3)
55 #define TEGRA_RTC_INTR_STATUS_MSEC_ALARM (1<<2)
56 #define TEGRA_RTC_INTR_STATUS_SEC_ALARM1 (1<<1)
57 #define TEGRA_RTC_INTR_STATUS_SEC_ALARM0 (1<<0)
58
59 struct tegra_rtc_info {
60 struct platform_device *pdev;
61 struct rtc_device *rtc_dev;
62 void __iomem *rtc_base; /* NULL if not initialized. */
63 struct clk *clk;
64 int tegra_rtc_irq; /* alarm and periodic irq */
65 spinlock_t tegra_rtc_lock;
66 };
67
68 /* RTC hardware is busy when it is updating its values over AHB once
69 * every eight 32kHz clocks (~250uS).
70 * outside of these updates the CPU is free to write.
71 * CPU is always free to read.
72 */
tegra_rtc_check_busy(struct tegra_rtc_info * info)73 static inline u32 tegra_rtc_check_busy(struct tegra_rtc_info *info)
74 {
75 return readl(info->rtc_base + TEGRA_RTC_REG_BUSY) & 1;
76 }
77
78 /* Wait for hardware to be ready for writing.
79 * This function tries to maximize the amount of time before the next update.
80 * It does this by waiting for the RTC to become busy with its periodic update,
81 * then returning once the RTC first becomes not busy.
82 * This periodic update (where the seconds and milliseconds are copied to the
83 * AHB side) occurs every eight 32kHz clocks (~250uS).
84 * The behavior of this function allows us to make some assumptions without
85 * introducing a race, because 250uS is plenty of time to read/write a value.
86 */
tegra_rtc_wait_while_busy(struct device * dev)87 static int tegra_rtc_wait_while_busy(struct device *dev)
88 {
89 struct tegra_rtc_info *info = dev_get_drvdata(dev);
90
91 int retries = 500; /* ~490 us is the worst case, ~250 us is best. */
92
93 /* first wait for the RTC to become busy. this is when it
94 * posts its updated seconds+msec registers to AHB side. */
95 while (tegra_rtc_check_busy(info)) {
96 if (!retries--)
97 goto retry_failed;
98 udelay(1);
99 }
100
101 /* now we have about 250 us to manipulate registers */
102 return 0;
103
104 retry_failed:
105 dev_err(dev, "write failed:retry count exceeded.\n");
106 return -ETIMEDOUT;
107 }
108
tegra_rtc_read_time(struct device * dev,struct rtc_time * tm)109 static int tegra_rtc_read_time(struct device *dev, struct rtc_time *tm)
110 {
111 struct tegra_rtc_info *info = dev_get_drvdata(dev);
112 unsigned long sec, msec;
113 unsigned long sl_irq_flags;
114
115 /* RTC hardware copies seconds to shadow seconds when a read
116 * of milliseconds occurs. use a lock to keep other threads out. */
117 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
118
119 msec = readl(info->rtc_base + TEGRA_RTC_REG_MILLI_SECONDS);
120 sec = readl(info->rtc_base + TEGRA_RTC_REG_SHADOW_SECONDS);
121
122 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
123
124 rtc_time_to_tm(sec, tm);
125
126 dev_vdbg(dev, "time read as %lu. %d/%d/%d %d:%02u:%02u\n",
127 sec,
128 tm->tm_mon + 1,
129 tm->tm_mday,
130 tm->tm_year + 1900,
131 tm->tm_hour,
132 tm->tm_min,
133 tm->tm_sec
134 );
135
136 return 0;
137 }
138
tegra_rtc_set_time(struct device * dev,struct rtc_time * tm)139 static int tegra_rtc_set_time(struct device *dev, struct rtc_time *tm)
140 {
141 struct tegra_rtc_info *info = dev_get_drvdata(dev);
142 unsigned long sec;
143 int ret;
144
145 /* convert tm to seconds. */
146 ret = rtc_valid_tm(tm);
147 if (ret)
148 return ret;
149
150 rtc_tm_to_time(tm, &sec);
151
152 dev_vdbg(dev, "time set to %lu. %d/%d/%d %d:%02u:%02u\n",
153 sec,
154 tm->tm_mon+1,
155 tm->tm_mday,
156 tm->tm_year+1900,
157 tm->tm_hour,
158 tm->tm_min,
159 tm->tm_sec
160 );
161
162 /* seconds only written if wait succeeded. */
163 ret = tegra_rtc_wait_while_busy(dev);
164 if (!ret)
165 writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS);
166
167 dev_vdbg(dev, "time read back as %d\n",
168 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS));
169
170 return ret;
171 }
172
tegra_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)173 static int tegra_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
174 {
175 struct tegra_rtc_info *info = dev_get_drvdata(dev);
176 unsigned long sec;
177 unsigned tmp;
178
179 sec = readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
180
181 if (sec == 0) {
182 /* alarm is disabled. */
183 alarm->enabled = 0;
184 alarm->time.tm_mon = -1;
185 alarm->time.tm_mday = -1;
186 alarm->time.tm_year = -1;
187 alarm->time.tm_hour = -1;
188 alarm->time.tm_min = -1;
189 alarm->time.tm_sec = -1;
190 } else {
191 /* alarm is enabled. */
192 alarm->enabled = 1;
193 rtc_time_to_tm(sec, &alarm->time);
194 }
195
196 tmp = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
197 alarm->pending = (tmp & TEGRA_RTC_INTR_STATUS_SEC_ALARM0) != 0;
198
199 return 0;
200 }
201
tegra_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)202 static int tegra_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
203 {
204 struct tegra_rtc_info *info = dev_get_drvdata(dev);
205 unsigned status;
206 unsigned long sl_irq_flags;
207
208 tegra_rtc_wait_while_busy(dev);
209 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
210
211 /* read the original value, and OR in the flag. */
212 status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
213 if (enabled)
214 status |= TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* set it */
215 else
216 status &= ~TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* clear it */
217
218 writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
219
220 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
221
222 return 0;
223 }
224
tegra_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)225 static int tegra_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
226 {
227 struct tegra_rtc_info *info = dev_get_drvdata(dev);
228 unsigned long sec;
229
230 if (alarm->enabled)
231 rtc_tm_to_time(&alarm->time, &sec);
232 else
233 sec = 0;
234
235 tegra_rtc_wait_while_busy(dev);
236 writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
237 dev_vdbg(dev, "alarm read back as %d\n",
238 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
239
240 /* if successfully written and alarm is enabled ... */
241 if (sec) {
242 tegra_rtc_alarm_irq_enable(dev, 1);
243
244 dev_vdbg(dev, "alarm set as %lu. %d/%d/%d %d:%02u:%02u\n",
245 sec,
246 alarm->time.tm_mon+1,
247 alarm->time.tm_mday,
248 alarm->time.tm_year+1900,
249 alarm->time.tm_hour,
250 alarm->time.tm_min,
251 alarm->time.tm_sec);
252 } else {
253 /* disable alarm if 0 or write error. */
254 dev_vdbg(dev, "alarm disabled\n");
255 tegra_rtc_alarm_irq_enable(dev, 0);
256 }
257
258 return 0;
259 }
260
tegra_rtc_proc(struct device * dev,struct seq_file * seq)261 static int tegra_rtc_proc(struct device *dev, struct seq_file *seq)
262 {
263 if (!dev || !dev->driver)
264 return 0;
265
266 seq_printf(seq, "name\t\t: %s\n", dev_name(dev));
267
268 return 0;
269 }
270
tegra_rtc_irq_handler(int irq,void * data)271 static irqreturn_t tegra_rtc_irq_handler(int irq, void *data)
272 {
273 struct device *dev = data;
274 struct tegra_rtc_info *info = dev_get_drvdata(dev);
275 unsigned long events = 0;
276 unsigned status;
277 unsigned long sl_irq_flags;
278
279 status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
280 if (status) {
281 /* clear the interrupt masks and status on any irq. */
282 tegra_rtc_wait_while_busy(dev);
283 spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
284 writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
285 writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
286 spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
287 }
288
289 /* check if Alarm */
290 if ((status & TEGRA_RTC_INTR_STATUS_SEC_ALARM0))
291 events |= RTC_IRQF | RTC_AF;
292
293 /* check if Periodic */
294 if ((status & TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM))
295 events |= RTC_IRQF | RTC_PF;
296
297 rtc_update_irq(info->rtc_dev, 1, events);
298
299 return IRQ_HANDLED;
300 }
301
302 static struct rtc_class_ops tegra_rtc_ops = {
303 .read_time = tegra_rtc_read_time,
304 .set_time = tegra_rtc_set_time,
305 .read_alarm = tegra_rtc_read_alarm,
306 .set_alarm = tegra_rtc_set_alarm,
307 .proc = tegra_rtc_proc,
308 .alarm_irq_enable = tegra_rtc_alarm_irq_enable,
309 };
310
311 static const struct of_device_id tegra_rtc_dt_match[] = {
312 { .compatible = "nvidia,tegra20-rtc", },
313 {}
314 };
315 MODULE_DEVICE_TABLE(of, tegra_rtc_dt_match);
316
tegra_rtc_probe(struct platform_device * pdev)317 static int __init tegra_rtc_probe(struct platform_device *pdev)
318 {
319 struct tegra_rtc_info *info;
320 struct resource *res;
321 int ret;
322
323 info = devm_kzalloc(&pdev->dev, sizeof(struct tegra_rtc_info),
324 GFP_KERNEL);
325 if (!info)
326 return -ENOMEM;
327
328 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
329 info->rtc_base = devm_ioremap_resource(&pdev->dev, res);
330 if (IS_ERR(info->rtc_base))
331 return PTR_ERR(info->rtc_base);
332
333 info->tegra_rtc_irq = platform_get_irq(pdev, 0);
334 if (info->tegra_rtc_irq <= 0)
335 return -EBUSY;
336
337 info->clk = devm_clk_get(&pdev->dev, NULL);
338 if (IS_ERR(info->clk))
339 return PTR_ERR(info->clk);
340
341 ret = clk_prepare_enable(info->clk);
342 if (ret < 0)
343 return ret;
344
345 /* set context info. */
346 info->pdev = pdev;
347 spin_lock_init(&info->tegra_rtc_lock);
348
349 platform_set_drvdata(pdev, info);
350
351 /* clear out the hardware. */
352 writel(0, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
353 writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
354 writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
355
356 device_init_wakeup(&pdev->dev, 1);
357
358 info->rtc_dev = devm_rtc_device_register(&pdev->dev,
359 dev_name(&pdev->dev), &tegra_rtc_ops,
360 THIS_MODULE);
361 if (IS_ERR(info->rtc_dev)) {
362 ret = PTR_ERR(info->rtc_dev);
363 dev_err(&pdev->dev, "Unable to register device (err=%d).\n",
364 ret);
365 goto disable_clk;
366 }
367
368 ret = devm_request_irq(&pdev->dev, info->tegra_rtc_irq,
369 tegra_rtc_irq_handler, IRQF_TRIGGER_HIGH,
370 dev_name(&pdev->dev), &pdev->dev);
371 if (ret) {
372 dev_err(&pdev->dev,
373 "Unable to request interrupt for device (err=%d).\n",
374 ret);
375 goto disable_clk;
376 }
377
378 dev_notice(&pdev->dev, "Tegra internal Real Time Clock\n");
379
380 return 0;
381
382 disable_clk:
383 clk_disable_unprepare(info->clk);
384 return ret;
385 }
386
tegra_rtc_remove(struct platform_device * pdev)387 static int tegra_rtc_remove(struct platform_device *pdev)
388 {
389 struct tegra_rtc_info *info = platform_get_drvdata(pdev);
390
391 clk_disable_unprepare(info->clk);
392
393 return 0;
394 }
395
396 #ifdef CONFIG_PM_SLEEP
tegra_rtc_suspend(struct device * dev)397 static int tegra_rtc_suspend(struct device *dev)
398 {
399 struct tegra_rtc_info *info = dev_get_drvdata(dev);
400
401 tegra_rtc_wait_while_busy(dev);
402
403 /* only use ALARM0 as a wake source. */
404 writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
405 writel(TEGRA_RTC_INTR_STATUS_SEC_ALARM0,
406 info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
407
408 dev_vdbg(dev, "alarm sec = %d\n",
409 readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
410
411 dev_vdbg(dev, "Suspend (device_may_wakeup=%d) irq:%d\n",
412 device_may_wakeup(dev), info->tegra_rtc_irq);
413
414 /* leave the alarms on as a wake source. */
415 if (device_may_wakeup(dev))
416 enable_irq_wake(info->tegra_rtc_irq);
417
418 return 0;
419 }
420
tegra_rtc_resume(struct device * dev)421 static int tegra_rtc_resume(struct device *dev)
422 {
423 struct tegra_rtc_info *info = dev_get_drvdata(dev);
424
425 dev_vdbg(dev, "Resume (device_may_wakeup=%d)\n",
426 device_may_wakeup(dev));
427 /* alarms were left on as a wake source, turn them off. */
428 if (device_may_wakeup(dev))
429 disable_irq_wake(info->tegra_rtc_irq);
430
431 return 0;
432 }
433 #endif
434
435 static SIMPLE_DEV_PM_OPS(tegra_rtc_pm_ops, tegra_rtc_suspend, tegra_rtc_resume);
436
tegra_rtc_shutdown(struct platform_device * pdev)437 static void tegra_rtc_shutdown(struct platform_device *pdev)
438 {
439 dev_vdbg(&pdev->dev, "disabling interrupts.\n");
440 tegra_rtc_alarm_irq_enable(&pdev->dev, 0);
441 }
442
443 MODULE_ALIAS("platform:tegra_rtc");
444 static struct platform_driver tegra_rtc_driver = {
445 .remove = tegra_rtc_remove,
446 .shutdown = tegra_rtc_shutdown,
447 .driver = {
448 .name = "tegra_rtc",
449 .of_match_table = tegra_rtc_dt_match,
450 .pm = &tegra_rtc_pm_ops,
451 },
452 };
453
454 module_platform_driver_probe(tegra_rtc_driver, tegra_rtc_probe);
455
456 MODULE_AUTHOR("Jon Mayo <jmayo@nvidia.com>");
457 MODULE_DESCRIPTION("driver for Tegra internal RTC");
458 MODULE_LICENSE("GPL");
459