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