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 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");