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                 return ret;
 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         return ret;
 129 }
 130
 131 static void sa1100_rtc_release(struct device *dev)
 132 {
 133         struct sa1100_rtc *info = dev_get_drvdata(dev);
 134
 135         spin_lock_irq(&info->lock);
 136         RTSR = 0;
 137         spin_unlock_irq(&info->lock);
 138
 139         free_irq(info->irq_alarm, dev);
 140         free_irq(info->irq_1hz, dev);
 141 }
 142
 143 static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 144 {
 145         struct sa1100_rtc *info = dev_get_drvdata(dev);
 146
 147         spin_lock_irq(&info->lock);
 148         if (enabled)
 149                 RTSR |= RTSR_ALE;
 150         else
 151                 RTSR &= ~RTSR_ALE;
 152         spin_unlock_irq(&info->lock);
 153         return 0;
 154 }
 155
 156 static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 157 {
 158         rtc_time_to_tm(RCNR, tm);
 159         return 0;
 160 }
 161
 162 static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 163 {
 164         unsigned long time;
 165         int ret;
 166
 167         ret = rtc_tm_to_time(tm, &time);
 168         if (ret == 0)
 169                 RCNR = time;
 170         return ret;
 171 }
 172
 173 static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 174 {
 175         u32     rtsr;
 176
 177         rtsr = RTSR;
 178         alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 179         alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 180         return 0;
 181 }
 182
 183 static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 184 {
 185         struct sa1100_rtc *info = dev_get_drvdata(dev);
 186         unsigned long time;
 187         int ret;
 188
 189         spin_lock_irq(&info->lock);
 190         ret = rtc_tm_to_time(&alrm->time, &time);
 191         if (ret != 0)
 192                 goto out;
 193         RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
 194         RTAR = time;
 195         if (alrm->enabled)
 196                 RTSR |= RTSR_ALE;
 197         else
 198                 RTSR &= ~RTSR_ALE;
 199 out:
 200         spin_unlock_irq(&info->lock);
 201
 202         return ret;
 203 }
 204
 205 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 206 {
 207         seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
 208         seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
 209
 210         return 0;
 211 }
 212
 213 static const struct rtc_class_ops sa1100_rtc_ops = {
 214         .open = sa1100_rtc_open,
 215         .release = sa1100_rtc_release,
 216         .read_time = sa1100_rtc_read_time,
 217         .set_time = sa1100_rtc_set_time,
 218         .read_alarm = sa1100_rtc_read_alarm,
 219         .set_alarm = sa1100_rtc_set_alarm,
 220         .proc = sa1100_rtc_proc,
 221         .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
 222 };
 223
 224 static int sa1100_rtc_probe(struct platform_device *pdev)
 225 {
 226         struct rtc_device *rtc;
 227         struct sa1100_rtc *info;
 228         int irq_1hz, irq_alarm, ret = 0;
 229
 230         irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
 231         irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
 232         if (irq_1hz < 0 || irq_alarm < 0)
 233                 return -ENODEV;
 234
 235         info = devm_kzalloc(&pdev->dev, sizeof(struct sa1100_rtc), GFP_KERNEL);
 236         if (!info)
 237                 return -ENOMEM;
 238         info->clk = devm_clk_get(&pdev->dev, NULL);
 239         if (IS_ERR(info->clk)) {
 240                 dev_err(&pdev->dev, "failed to find rtc clock source\n");
 241                 return PTR_ERR(info->clk);
 242         }
 243         info->irq_1hz = irq_1hz;
 244         info->irq_alarm = irq_alarm;
 245         spin_lock_init(&info->lock);
 246         platform_set_drvdata(pdev, info);
 247
 248         ret = clk_prepare_enable(info->clk);
 249         if (ret)
 250                 return ret;
 251         /*
 252          * According to the manual we should be able to let RTTR be zero
 253          * and then a default diviser for a 32.768KHz clock is used.
 254          * Apparently this doesn't work, at least for my SA1110 rev 5.
 255          * If the clock divider is uninitialized then reset it to the
 256          * default value to get the 1Hz clock.
 257          */
 258         if (RTTR == 0) {
 259                 RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 260                 dev_warn(&pdev->dev, "warning: "
 261                         "initializing default clock divider/trim value\n");
 262                 /* The current RTC value probably doesn't make sense either */
 263                 RCNR = 0;
 264         }
 265
 266         device_init_wakeup(&pdev->dev, 1);
 267
 268         rtc = devm_rtc_device_register(&pdev->dev, pdev->name, &sa1100_rtc_ops,
 269                                         THIS_MODULE);
 270
 271         if (IS_ERR(rtc)) {
 272                 ret = PTR_ERR(rtc);
 273                 goto err_dev;
 274         }
 275         info->rtc = rtc;
 276
 277         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 278          * See also the comments in sa1100_rtc_interrupt().
 279          *
 280          * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
 281          * interrupt pending, even though interrupts were never enabled.
 282          * In this case, this bit it must be reset before enabling
 283          * interruptions to avoid a nonexistent interrupt to occur.
 284          *
 285          * In principle, the same problem would apply to bit 0, although it has
 286          * never been observed to happen.
 287          *
 288          * This issue is addressed both here and in sa1100_rtc_interrupt().
 289          * If the issue is not addressed here, in the times when the processor
 290          * wakes up with the bit set there will be one spurious interrupt.
 291          *
 292          * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
 293          * safe side, once the condition that lead to this strange
 294          * initialization is unknown and could in principle happen during
 295          * normal processing.
 296          *
 297          * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
 298          * the corresponding bits in RTSR. */
 299         RTSR = RTSR_AL | RTSR_HZ;
 300
 301         return 0;
 302 err_dev:
 303         clk_disable_unprepare(info->clk);
 304         return ret;
 305 }
 306
 307 static int sa1100_rtc_remove(struct platform_device *pdev)
 308 {
 309         struct sa1100_rtc *info = platform_get_drvdata(pdev);
 310
 311         if (info)
 312                 clk_disable_unprepare(info->clk);
 313
 314         return 0;
 315 }
 316
 317 #ifdef CONFIG_PM_SLEEP
 318 static int sa1100_rtc_suspend(struct device *dev)
 319 {
 320         struct sa1100_rtc *info = dev_get_drvdata(dev);
 321         if (device_may_wakeup(dev))
 322                 enable_irq_wake(info->irq_alarm);
 323         return 0;
 324 }
 325
 326 static int sa1100_rtc_resume(struct device *dev)
 327 {
 328         struct sa1100_rtc *info = dev_get_drvdata(dev);
 329         if (device_may_wakeup(dev))
 330                 disable_irq_wake(info->irq_alarm);
 331         return 0;
 332 }
 333 #endif
 334
 335 static SIMPLE_DEV_PM_OPS(sa1100_rtc_pm_ops, sa1100_rtc_suspend,
 336                         sa1100_rtc_resume);
 337
 338 #ifdef CONFIG_OF
 339 static const struct of_device_id sa1100_rtc_dt_ids[] = {
 340         { .compatible = "mrvl,sa1100-rtc", },
 341         { .compatible = "mrvl,mmp-rtc", },
 342         {}
 343 };
 344 MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);
 345 #endif
 346
 347 static struct platform_driver sa1100_rtc_driver = {
 348         .probe          = sa1100_rtc_probe,
 349         .remove         = sa1100_rtc_remove,
 350         .driver         = {
 351                 .name   = "sa1100-rtc",
 352                 .pm     = &sa1100_rtc_pm_ops,
 353                 .of_match_table = of_match_ptr(sa1100_rtc_dt_ids),
 354         },
 355 };
 356
 357 module_platform_driver(sa1100_rtc_driver);
 358
 359 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 360 MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 361 MODULE_LICENSE("GPL");
 362 MODULE_ALIAS("platform:sa1100-rtc");