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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 #define RTSR_HZE                BIT(3)  /* HZ interrupt enable */
 39 #define RTSR_ALE                BIT(2)  /* RTC alarm interrupt enable */
 40 #define RTSR_HZ                 BIT(1)  /* HZ rising-edge detected */
 41 #define RTSR_AL                 BIT(0)  /* RTC alarm detected */
 42 
 43 #include "rtc-sa1100.h"
 44 
 45 #define RTC_DEF_DIVIDER         (32768 - 1)
 46 #define RTC_DEF_TRIM            0
 47 #define RTC_FREQ                1024
 48 
 49 
 50 static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
 51 {
 52         struct sa1100_rtc *info = dev_get_drvdata(dev_id);
 53         struct rtc_device *rtc = info->rtc;
 54         unsigned int rtsr;
 55         unsigned long events = 0;
 56 
 57         spin_lock(&info->lock);
 58 
 59         rtsr = readl_relaxed(info->rtsr);
 60         /* clear interrupt sources */
 61         writel_relaxed(0, info->rtsr);
 62         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 63          * See also the comments in sa1100_rtc_probe(). */
 64         if (rtsr & (RTSR_ALE | RTSR_HZE)) {
 65                 /* This is the original code, before there was the if test
 66                  * above. This code does not clear interrupts that were not
 67                  * enabled. */
 68                 writel_relaxed((RTSR_AL | RTSR_HZ) & (rtsr >> 2), info->rtsr);
 69         } else {
 70                 /* For some reason, it is possible to enter this routine
 71                  * without interruptions enabled, it has been tested with
 72                  * several units (Bug in SA11xx chip?).
 73                  *
 74                  * This situation leads to an infinite "loop" of interrupt
 75                  * routine calling and as a result the processor seems to
 76                  * lock on its first call to open(). */
 77                 writel_relaxed(RTSR_AL | RTSR_HZ, info->rtsr);
 78         }
 79 
 80         /* clear alarm interrupt if it has occurred */
 81         if (rtsr & RTSR_AL)
 82                 rtsr &= ~RTSR_ALE;
 83         writel_relaxed(rtsr & (RTSR_ALE | RTSR_HZE), info->rtsr);
 84 
 85         /* update irq data & counter */
 86         if (rtsr & RTSR_AL)
 87                 events |= RTC_AF | RTC_IRQF;
 88         if (rtsr & RTSR_HZ)
 89                 events |= RTC_UF | RTC_IRQF;
 90 
 91         rtc_update_irq(rtc, 1, events);
 92 
 93         spin_unlock(&info->lock);
 94 
 95         return IRQ_HANDLED;
 96 }
 97 
 98 static int sa1100_rtc_open(struct device *dev)
 99 {
100         struct sa1100_rtc *info = dev_get_drvdata(dev);
101         struct rtc_device *rtc = info->rtc;
102         int ret;
103 
104         ret = request_irq(info->irq_1hz, sa1100_rtc_interrupt, 0, "rtc 1Hz", dev);
105         if (ret) {
106                 dev_err(dev, "IRQ %d already in use.\n", info->irq_1hz);
107                 goto fail_ui;
108         }
109         ret = request_irq(info->irq_alarm, sa1100_rtc_interrupt, 0, "rtc Alrm", dev);
110         if (ret) {
111                 dev_err(dev, "IRQ %d already in use.\n", info->irq_alarm);
112                 goto fail_ai;
113         }
114         rtc->max_user_freq = RTC_FREQ;
115         rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
116 
117         return 0;
118 
119  fail_ai:
120         free_irq(info->irq_1hz, dev);
121  fail_ui:
122         clk_disable_unprepare(info->clk);
123         return ret;
124 }
125 
126 static void sa1100_rtc_release(struct device *dev)
127 {
128         struct sa1100_rtc *info = dev_get_drvdata(dev);
129 
130         spin_lock_irq(&info->lock);
131         writel_relaxed(0, info->rtsr);
132         spin_unlock_irq(&info->lock);
133 
134         free_irq(info->irq_alarm, dev);
135         free_irq(info->irq_1hz, dev);
136 }
137 
138 static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
139 {
140         u32 rtsr;
141         struct sa1100_rtc *info = dev_get_drvdata(dev);
142 
143         spin_lock_irq(&info->lock);
144         rtsr = readl_relaxed(info->rtsr);
145         if (enabled)
146                 rtsr |= RTSR_ALE;
147         else
148                 rtsr &= ~RTSR_ALE;
149         writel_relaxed(rtsr, info->rtsr);
150         spin_unlock_irq(&info->lock);
151         return 0;
152 }
153 
154 static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
155 {
156         struct sa1100_rtc *info = dev_get_drvdata(dev);
157 
158         rtc_time_to_tm(readl_relaxed(info->rcnr), tm);
159         return 0;
160 }
161 
162 static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
163 {
164         struct sa1100_rtc *info = dev_get_drvdata(dev);
165         unsigned long time;
166         int ret;
167 
168         ret = rtc_tm_to_time(tm, &time);
169         if (ret == 0)
170                 writel_relaxed(time, info->rcnr);
171         return ret;
172 }
173 
174 static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
175 {
176         u32     rtsr;
177         struct sa1100_rtc *info = dev_get_drvdata(dev);
178 
179         rtsr = readl_relaxed(info->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         writel_relaxed(readl_relaxed(info->rtsr) &
196                 (RTSR_HZE | RTSR_ALE | RTSR_AL), info->rtsr);
197         writel_relaxed(time, info->rtar);
198         if (alrm->enabled)
199                 writel_relaxed(readl_relaxed(info->rtsr) | RTSR_ALE, info->rtsr);
200         else
201                 writel_relaxed(readl_relaxed(info->rtsr) & ~RTSR_ALE, info->rtsr);
202 out:
203         spin_unlock_irq(&info->lock);
204 
205         return ret;
206 }
207 
208 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
209 {
210         struct sa1100_rtc *info = dev_get_drvdata(dev);
211 
212         seq_printf(seq, "trim/divider\t\t: 0x%08x\n", readl_relaxed(info->rttr));
213         seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", readl_relaxed(info->rtsr));
214 
215         return 0;
216 }
217 
218 static const struct rtc_class_ops sa1100_rtc_ops = {
219         .open = sa1100_rtc_open,
220         .release = sa1100_rtc_release,
221         .read_time = sa1100_rtc_read_time,
222         .set_time = sa1100_rtc_set_time,
223         .read_alarm = sa1100_rtc_read_alarm,
224         .set_alarm = sa1100_rtc_set_alarm,
225         .proc = sa1100_rtc_proc,
226         .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
227 };
228 
229 int sa1100_rtc_init(struct platform_device *pdev, struct sa1100_rtc *info)
230 {
231         struct rtc_device *rtc;
232         int ret;
233 
234         spin_lock_init(&info->lock);
235 
236         info->clk = devm_clk_get(&pdev->dev, NULL);
237         if (IS_ERR(info->clk)) {
238                 dev_err(&pdev->dev, "failed to find rtc clock source\n");
239                 return PTR_ERR(info->clk);
240         }
241 
242         ret = clk_prepare_enable(info->clk);
243         if (ret)
244                 return ret;
245         /*
246          * According to the manual we should be able to let RTTR be zero
247          * and then a default diviser for a 32.768KHz clock is used.
248          * Apparently this doesn't work, at least for my SA1110 rev 5.
249          * If the clock divider is uninitialized then reset it to the
250          * default value to get the 1Hz clock.
251          */
252         if (readl_relaxed(info->rttr) == 0) {
253                 writel_relaxed(RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16), info->rttr);
254                 dev_warn(&pdev->dev, "warning: "
255                         "initializing default clock divider/trim value\n");
256                 /* The current RTC value probably doesn't make sense either */
257                 writel_relaxed(0, info->rcnr);
258         }
259 
260         rtc = devm_rtc_device_register(&pdev->dev, pdev->name, &sa1100_rtc_ops,
261                                         THIS_MODULE);
262         if (IS_ERR(rtc)) {
263                 clk_disable_unprepare(info->clk);
264                 return PTR_ERR(rtc);
265         }
266         info->rtc = rtc;
267 
268         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
269          * See also the comments in sa1100_rtc_interrupt().
270          *
271          * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
272          * interrupt pending, even though interrupts were never enabled.
273          * In this case, this bit it must be reset before enabling
274          * interruptions to avoid a nonexistent interrupt to occur.
275          *
276          * In principle, the same problem would apply to bit 0, although it has
277          * never been observed to happen.
278          *
279          * This issue is addressed both here and in sa1100_rtc_interrupt().
280          * If the issue is not addressed here, in the times when the processor
281          * wakes up with the bit set there will be one spurious interrupt.
282          *
283          * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
284          * safe side, once the condition that lead to this strange
285          * initialization is unknown and could in principle happen during
286          * normal processing.
287          *
288          * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
289          * the corresponding bits in RTSR. */
290         writel_relaxed(RTSR_AL | RTSR_HZ, info->rtsr);
291 
292         return 0;
293 }
294 EXPORT_SYMBOL_GPL(sa1100_rtc_init);
295 
296 static int sa1100_rtc_probe(struct platform_device *pdev)
297 {
298         struct sa1100_rtc *info;
299         struct resource *iores;
300         void __iomem *base;
301         int irq_1hz, irq_alarm;
302 
303         irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
304         irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
305         if (irq_1hz < 0 || irq_alarm < 0)
306                 return -ENODEV;
307 
308         info = devm_kzalloc(&pdev->dev, sizeof(struct sa1100_rtc), GFP_KERNEL);
309         if (!info)
310                 return -ENOMEM;
311         info->irq_1hz = irq_1hz;
312         info->irq_alarm = irq_alarm;
313 
314         iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
315         base = devm_ioremap_resource(&pdev->dev, iores);
316         if (IS_ERR(base))
317                 return PTR_ERR(base);
318 
319         if (IS_ENABLED(CONFIG_ARCH_SA1100) ||
320             of_device_is_compatible(pdev->dev.of_node, "mrvl,sa1100-rtc")) {
321                 info->rcnr = base + 0x04;
322                 info->rtsr = base + 0x10;
323                 info->rtar = base + 0x00;
324                 info->rttr = base + 0x08;
325         } else {
326                 info->rcnr = base + 0x0;
327                 info->rtsr = base + 0x8;
328                 info->rtar = base + 0x4;
329                 info->rttr = base + 0xc;
330         }
331 
332         platform_set_drvdata(pdev, info);
333         device_init_wakeup(&pdev->dev, 1);
334 
335         return sa1100_rtc_init(pdev, info);
336 }
337 
338 static int sa1100_rtc_remove(struct platform_device *pdev)
339 {
340         struct sa1100_rtc *info = platform_get_drvdata(pdev);
341 
342         if (info)
343                 clk_disable_unprepare(info->clk);
344 
345         return 0;
346 }
347 
348 #ifdef CONFIG_PM_SLEEP
349 static int sa1100_rtc_suspend(struct device *dev)
350 {
351         struct sa1100_rtc *info = dev_get_drvdata(dev);
352         if (device_may_wakeup(dev))
353                 enable_irq_wake(info->irq_alarm);
354         return 0;
355 }
356 
357 static int sa1100_rtc_resume(struct device *dev)
358 {
359         struct sa1100_rtc *info = dev_get_drvdata(dev);
360         if (device_may_wakeup(dev))
361                 disable_irq_wake(info->irq_alarm);
362         return 0;
363 }
364 #endif
365 
366 static SIMPLE_DEV_PM_OPS(sa1100_rtc_pm_ops, sa1100_rtc_suspend,
367                         sa1100_rtc_resume);
368 
369 #ifdef CONFIG_OF
370 static const struct of_device_id sa1100_rtc_dt_ids[] = {
371         { .compatible = "mrvl,sa1100-rtc", },
372         { .compatible = "mrvl,mmp-rtc", },
373         {}
374 };
375 MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);
376 #endif
377 
378 static struct platform_driver sa1100_rtc_driver = {
379         .probe          = sa1100_rtc_probe,
380         .remove         = sa1100_rtc_remove,
381         .driver         = {
382                 .name   = "sa1100-rtc",
383                 .pm     = &sa1100_rtc_pm_ops,
384                 .of_match_table = of_match_ptr(sa1100_rtc_dt_ids),
385         },
386 };
387 
388 module_platform_driver(sa1100_rtc_driver);
389 
390 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
391 MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
392 MODULE_LICENSE("GPL");
393 MODULE_ALIAS("platform:sa1100-rtc");
394 

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