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Linux/drivers/rtc/rtc-sa1100.c

  1 /*
  2  * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
  3  *
  4  * Copyright (c) 2000 Nils Faerber
  5  *
  6  * Based on rtc.c by Paul Gortmaker
  7  *
  8  * Original Driver by Nils Faerber <nils@kernelconcepts.de>
  9  *
 10  * Modifications from:
 11  *   CIH <cih@coventive.com>
 12  *   Nicolas Pitre <nico@fluxnic.net>
 13  *   Andrew Christian <andrew.christian@hp.com>
 14  *
 15  * Converted to the RTC subsystem and Driver Model
 16  *   by Richard Purdie <rpurdie@rpsys.net>
 17  *
 18  * This program is free software; you can redistribute it and/or
 19  * modify it under the terms of the GNU General Public License
 20  * as published by the Free Software Foundation; either version
 21  * 2 of the License, or (at your option) any later version.
 22  */
 23 
 24 #include <linux/platform_device.h>
 25 #include <linux/module.h>
 26 #include <linux/clk.h>
 27 #include <linux/rtc.h>
 28 #include <linux/init.h>
 29 #include <linux/fs.h>
 30 #include <linux/interrupt.h>
 31 #include <linux/slab.h>
 32 #include <linux/string.h>
 33 #include <linux/of.h>
 34 #include <linux/pm.h>
 35 #include <linux/bitops.h>
 36 #include <linux/io.h>
 37 
 38 #include <mach/hardware.h>
 39 #include <mach/irqs.h>
 40 
 41 #if defined(CONFIG_ARCH_PXA) || defined(CONFIG_ARCH_MMP)
 42 #include <mach/regs-rtc.h>
 43 #endif
 44 
 45 #define RTC_DEF_DIVIDER         (32768 - 1)
 46 #define RTC_DEF_TRIM            0
 47 #define RTC_FREQ                1024
 48 
 49 struct sa1100_rtc {
 50         spinlock_t              lock;
 51         int                     irq_1hz;
 52         int                     irq_alarm;
 53         struct rtc_device       *rtc;
 54         struct clk              *clk;
 55 };
 56 
 57 static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
 58 {
 59         struct sa1100_rtc *info = dev_get_drvdata(dev_id);
 60         struct rtc_device *rtc = info->rtc;
 61         unsigned int rtsr;
 62         unsigned long events = 0;
 63 
 64         spin_lock(&info->lock);
 65 
 66         rtsr = RTSR;
 67         /* clear interrupt sources */
 68         RTSR = 0;
 69         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 70          * See also the comments in sa1100_rtc_probe(). */
 71         if (rtsr & (RTSR_ALE | RTSR_HZE)) {
 72                 /* This is the original code, before there was the if test
 73                  * above. This code does not clear interrupts that were not
 74                  * enabled. */
 75                 RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
 76         } else {
 77                 /* For some reason, it is possible to enter this routine
 78                  * without interruptions enabled, it has been tested with
 79                  * several units (Bug in SA11xx chip?).
 80                  *
 81                  * This situation leads to an infinite "loop" of interrupt
 82                  * routine calling and as a result the processor seems to
 83                  * lock on its first call to open(). */
 84                 RTSR = RTSR_AL | RTSR_HZ;
 85         }
 86 
 87         /* clear alarm interrupt if it has occurred */
 88         if (rtsr & RTSR_AL)
 89                 rtsr &= ~RTSR_ALE;
 90         RTSR = rtsr & (RTSR_ALE | RTSR_HZE);
 91 
 92         /* update irq data & counter */
 93         if (rtsr & RTSR_AL)
 94                 events |= RTC_AF | RTC_IRQF;
 95         if (rtsr & RTSR_HZ)
 96                 events |= RTC_UF | RTC_IRQF;
 97 
 98         rtc_update_irq(rtc, 1, events);
 99 
100         spin_unlock(&info->lock);
101 
102         return IRQ_HANDLED;
103 }
104 
105 static int sa1100_rtc_open(struct device *dev)
106 {
107         struct sa1100_rtc *info = dev_get_drvdata(dev);
108         struct rtc_device *rtc = info->rtc;
109         int ret;
110 
111         ret = request_irq(info->irq_1hz, sa1100_rtc_interrupt, 0, "rtc 1Hz", dev);
112         if (ret) {
113                 dev_err(dev, "IRQ %d already in use.\n", info->irq_1hz);
114                 goto fail_ui;
115         }
116         ret = request_irq(info->irq_alarm, sa1100_rtc_interrupt, 0, "rtc Alrm", dev);
117         if (ret) {
118                 dev_err(dev, "IRQ %d already in use.\n", info->irq_alarm);
119                 goto fail_ai;
120         }
121         rtc->max_user_freq = RTC_FREQ;
122         rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
123 
124         return 0;
125 
126  fail_ai:
127         free_irq(info->irq_1hz, dev);
128  fail_ui:
129         clk_disable_unprepare(info->clk);
130         return ret;
131 }
132 
133 static void sa1100_rtc_release(struct device *dev)
134 {
135         struct sa1100_rtc *info = dev_get_drvdata(dev);
136 
137         spin_lock_irq(&info->lock);
138         RTSR = 0;
139         spin_unlock_irq(&info->lock);
140 
141         free_irq(info->irq_alarm, dev);
142         free_irq(info->irq_1hz, dev);
143 }
144 
145 static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
146 {
147         struct sa1100_rtc *info = dev_get_drvdata(dev);
148 
149         spin_lock_irq(&info->lock);
150         if (enabled)
151                 RTSR |= RTSR_ALE;
152         else
153                 RTSR &= ~RTSR_ALE;
154         spin_unlock_irq(&info->lock);
155         return 0;
156 }
157 
158 static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
159 {
160         rtc_time_to_tm(RCNR, tm);
161         return 0;
162 }
163 
164 static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
165 {
166         unsigned long time;
167         int ret;
168 
169         ret = rtc_tm_to_time(tm, &time);
170         if (ret == 0)
171                 RCNR = time;
172         return ret;
173 }
174 
175 static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
176 {
177         u32     rtsr;
178 
179         rtsr = RTSR;
180         alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
181         alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
182         return 0;
183 }
184 
185 static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
186 {
187         struct sa1100_rtc *info = dev_get_drvdata(dev);
188         unsigned long time;
189         int ret;
190 
191         spin_lock_irq(&info->lock);
192         ret = rtc_tm_to_time(&alrm->time, &time);
193         if (ret != 0)
194                 goto out;
195         RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
196         RTAR = time;
197         if (alrm->enabled)
198                 RTSR |= RTSR_ALE;
199         else
200                 RTSR &= ~RTSR_ALE;
201 out:
202         spin_unlock_irq(&info->lock);
203 
204         return ret;
205 }
206 
207 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
208 {
209         seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
210         seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
211 
212         return 0;
213 }
214 
215 static const struct rtc_class_ops sa1100_rtc_ops = {
216         .open = sa1100_rtc_open,
217         .release = sa1100_rtc_release,
218         .read_time = sa1100_rtc_read_time,
219         .set_time = sa1100_rtc_set_time,
220         .read_alarm = sa1100_rtc_read_alarm,
221         .set_alarm = sa1100_rtc_set_alarm,
222         .proc = sa1100_rtc_proc,
223         .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
224 };
225 
226 static int sa1100_rtc_probe(struct platform_device *pdev)
227 {
228         struct rtc_device *rtc;
229         struct sa1100_rtc *info;
230         int irq_1hz, irq_alarm, ret = 0;
231 
232         irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
233         irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
234         if (irq_1hz < 0 || irq_alarm < 0)
235                 return -ENODEV;
236 
237         info = devm_kzalloc(&pdev->dev, sizeof(struct sa1100_rtc), GFP_KERNEL);
238         if (!info)
239                 return -ENOMEM;
240         info->clk = devm_clk_get(&pdev->dev, NULL);
241         if (IS_ERR(info->clk)) {
242                 dev_err(&pdev->dev, "failed to find rtc clock source\n");
243                 return PTR_ERR(info->clk);
244         }
245         info->irq_1hz = irq_1hz;
246         info->irq_alarm = irq_alarm;
247         spin_lock_init(&info->lock);
248         platform_set_drvdata(pdev, info);
249 
250         ret = clk_prepare_enable(info->clk);
251         if (ret)
252                 return ret;
253         /*
254          * According to the manual we should be able to let RTTR be zero
255          * and then a default diviser for a 32.768KHz clock is used.
256          * Apparently this doesn't work, at least for my SA1110 rev 5.
257          * If the clock divider is uninitialized then reset it to the
258          * default value to get the 1Hz clock.
259          */
260         if (RTTR == 0) {
261                 RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
262                 dev_warn(&pdev->dev, "warning: "
263                         "initializing default clock divider/trim value\n");
264                 /* The current RTC value probably doesn't make sense either */
265                 RCNR = 0;
266         }
267 
268         device_init_wakeup(&pdev->dev, 1);
269 
270         rtc = devm_rtc_device_register(&pdev->dev, pdev->name, &sa1100_rtc_ops,
271                                         THIS_MODULE);
272 
273         if (IS_ERR(rtc)) {
274                 ret = PTR_ERR(rtc);
275                 goto err_dev;
276         }
277         info->rtc = rtc;
278 
279         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
280          * See also the comments in sa1100_rtc_interrupt().
281          *
282          * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
283          * interrupt pending, even though interrupts were never enabled.
284          * In this case, this bit it must be reset before enabling
285          * interruptions to avoid a nonexistent interrupt to occur.
286          *
287          * In principle, the same problem would apply to bit 0, although it has
288          * never been observed to happen.
289          *
290          * This issue is addressed both here and in sa1100_rtc_interrupt().
291          * If the issue is not addressed here, in the times when the processor
292          * wakes up with the bit set there will be one spurious interrupt.
293          *
294          * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
295          * safe side, once the condition that lead to this strange
296          * initialization is unknown and could in principle happen during
297          * normal processing.
298          *
299          * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
300          * the corresponding bits in RTSR. */
301         RTSR = RTSR_AL | RTSR_HZ;
302 
303         return 0;
304 err_dev:
305         clk_disable_unprepare(info->clk);
306         return ret;
307 }
308 
309 static int sa1100_rtc_remove(struct platform_device *pdev)
310 {
311         struct sa1100_rtc *info = platform_get_drvdata(pdev);
312 
313         if (info)
314                 clk_disable_unprepare(info->clk);
315 
316         return 0;
317 }
318 
319 #ifdef CONFIG_PM_SLEEP
320 static int sa1100_rtc_suspend(struct device *dev)
321 {
322         struct sa1100_rtc *info = dev_get_drvdata(dev);
323         if (device_may_wakeup(dev))
324                 enable_irq_wake(info->irq_alarm);
325         return 0;
326 }
327 
328 static int sa1100_rtc_resume(struct device *dev)
329 {
330         struct sa1100_rtc *info = dev_get_drvdata(dev);
331         if (device_may_wakeup(dev))
332                 disable_irq_wake(info->irq_alarm);
333         return 0;
334 }
335 #endif
336 
337 static SIMPLE_DEV_PM_OPS(sa1100_rtc_pm_ops, sa1100_rtc_suspend,
338                         sa1100_rtc_resume);
339 
340 #ifdef CONFIG_OF
341 static const struct of_device_id sa1100_rtc_dt_ids[] = {
342         { .compatible = "mrvl,sa1100-rtc", },
343         { .compatible = "mrvl,mmp-rtc", },
344         {}
345 };
346 MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);
347 #endif
348 
349 static struct platform_driver sa1100_rtc_driver = {
350         .probe          = sa1100_rtc_probe,
351         .remove         = sa1100_rtc_remove,
352         .driver         = {
353                 .name   = "sa1100-rtc",
354                 .pm     = &sa1100_rtc_pm_ops,
355                 .of_match_table = of_match_ptr(sa1100_rtc_dt_ids),
356         },
357 };
358 
359 module_platform_driver(sa1100_rtc_driver);
360 
361 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
362 MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
363 MODULE_LICENSE("GPL");
364 MODULE_ALIAS("platform:sa1100-rtc");
365 

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