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");