RTC（实时钟）设备驱动（内核代码）

代码在：drivers/rtc/rtc-dev.c

/* drivers/rtc/rtc-s3c.c
 *
 * Copyright (c) 2004,2006 Simtec Electronics
 * Ben Dooks,
 * http://armlinux.simtec.co.uk/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * S3C2410/S3C2440/S3C24XX Internal RTC Driver
*/

#include
#include
#include
#include
#include
#include
#include
#include
#include

#include
#include
#include
#include
#include

#include

#include

/* I have yet to find an S3C implementation with more than one
 * of these rtc blocks in */

static struct resource *s3c_rtc_mem;

static void __iomem *s3c_rtc_base;
static int s3c_rtc_alarmno = NO_IRQ;
static int s3c_rtc_tickno  = NO_IRQ;
static int s3c_rtc_freq    = 1;

static DEFINE_SPINLOCK(s3c_rtc_pie_lock);
static unsigned int tick_count;

/* IRQ Handlers */

static irqreturn_t s3c_rtc_alarmirq(int irq, void *id)
{
 struct rtc_device *rdev = id;

 rtc_update_irq(rdev, 1, RTC_AF | RTC_IRQF);
 return IRQ_HANDLED;
}

static irqreturn_t s3c_rtc_tickirq(int irq, void *id)
{
 struct rtc_device *rdev = id;

 rtc_update_irq(rdev, tick_count++, RTC_PF | RTC_IRQF);
 return IRQ_HANDLED;
}

/* Update control registers */
static void s3c_rtc_setaie(int to)
{
 unsigned int tmp;

 pr_debug("%s: aie=%d\n", __FUNCTION__, to);

 tmp = readb(s3c_rtc_base + S3C2410_RTCALM) & ~S3C2410_RTCALM_ALMEN;

 if (to)
  tmp |= S3C2410_RTCALM_ALMEN;

 writeb(tmp, s3c_rtc_base + S3C2410_RTCALM);
}

static void s3c_rtc_setpie(int to)
{
 unsigned int tmp;

 pr_debug("%s: pie=%d\n", __FUNCTION__, to);

 spin_lock_irq(&s3c_rtc_pie_lock);
 tmp = readb(s3c_rtc_base + S3C2410_TICNT) & ~S3C2410_TICNT_ENABLE;

 if (to)
  tmp |= S3C2410_TICNT_ENABLE;

 writeb(tmp, s3c_rtc_base + S3C2410_TICNT);
 spin_unlock_irq(&s3c_rtc_pie_lock);
}

static void s3c_rtc_setfreq(int freq)
{
 unsigned int tmp;

 spin_lock_irq(&s3c_rtc_pie_lock);
 tmp = readb(s3c_rtc_base + S3C2410_TICNT) & S3C2410_TICNT_ENABLE;

 s3c_rtc_freq = freq;

 tmp |= (128 / freq)-1;

 writeb(tmp, s3c_rtc_base + S3C2410_TICNT);
 spin_unlock_irq(&s3c_rtc_pie_lock);
}

/* Time read/write */

static int s3c_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
{
 unsigned int have_retried = 0;
 void __iomem *base = s3c_rtc_base;

 retry_get_time:
 rtc_tm->tm_min  = readb(base + S3C2410_RTCMIN);
 rtc_tm->tm_hour = readb(base + S3C2410_RTCHOUR);
 rtc_tm->tm_mday = readb(base + S3C2410_RTCDATE);
 rtc_tm->tm_mon  = readb(base + S3C2410_RTCMON);
 rtc_tm->tm_year = readb(base + S3C2410_RTCYEAR);
 rtc_tm->tm_sec  = readb(base + S3C2410_RTCSEC);

 /* the only way to work out wether the system was mid-update
  * when we read it is to check the second counter, and if it
  * is zero, then we re-try the entire read
  */

 if (rtc_tm->tm_sec == 0 && !have_retried) {
  have_retried = 1;
  goto retry_get_time;
 }

 pr_debug("read time %02x.%02x.%02x %02x/%02x/%02x\n",
   rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,
   rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);

 BCD_TO_BIN(rtc_tm->tm_sec);
 BCD_TO_BIN(rtc_tm->tm_min);
 BCD_TO_BIN(rtc_tm->tm_hour);
 BCD_TO_BIN(rtc_tm->tm_mday);
 BCD_TO_BIN(rtc_tm->tm_mon);
 BCD_TO_BIN(rtc_tm->tm_year);

 rtc_tm->tm_year += 100;
 rtc_tm->tm_mon -= 1;

 return 0;
}

static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
{
 void __iomem *base = s3c_rtc_base;
 int year = tm->tm_year - 100;

 pr_debug("set time %02d.%02d.%02d %02d/%02d/%02d\n",
   tm->tm_year, tm->tm_mon, tm->tm_mday,
   tm->tm_hour, tm->tm_min, tm->tm_sec);

 /* we get around y2k by simply not supporting it */

 if (year < 0 || year >= 100) {
  dev_err(dev, "rtc only supports 100 years\n");
  return -EINVAL;
 }

 writeb(BIN2BCD(tm->tm_sec),  base + S3C2410_RTCSEC);
 writeb(BIN2BCD(tm->tm_min),  base + S3C2410_RTCMIN);
 writeb(BIN2BCD(tm->tm_hour), base + S3C2410_RTCHOUR);
 writeb(BIN2BCD(tm->tm_mday), base + S3C2410_RTCDATE);
 writeb(BIN2BCD(tm->tm_mon + 1), base + S3C2410_RTCMON);
 writeb(BIN2BCD(year), base + S3C2410_RTCYEAR);

 return 0;
}

static int s3c_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
 struct rtc_time *alm_tm = &alrm->time;
 void __iomem *base = s3c_rtc_base;
 unsigned int alm_en;

 alm_tm->tm_sec  = readb(base + S3C2410_ALMSEC);
 alm_tm->tm_min  = readb(base + S3C2410_ALMMIN);
 alm_tm->tm_hour = readb(base + S3C2410_ALMHOUR);
 alm_tm->tm_mon  = readb(base + S3C2410_ALMMON);
 alm_tm->tm_mday = readb(base + S3C2410_ALMDATE);
 alm_tm->tm_year = readb(base + S3C2410_ALMYEAR);

 alm_en = readb(base + S3C2410_RTCALM);

 alrm->enabled = (alm_en & S3C2410_RTCALM_ALMEN) ? 1 : 0;

 pr_debug("read alarm %02x %02x.%02x.%02x %02x/%02x/%02x\n",
   alm_en,
   alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday,
   alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);

 /* decode the alarm enable field */

 if (alm_en & S3C2410_RTCALM_SECEN)
  BCD_TO_BIN(alm_tm->tm_sec);
 else
  alm_tm->tm_sec = 0xff;

 if (alm_en & S3C2410_RTCALM_MINEN)
  BCD_TO_BIN(alm_tm->tm_min);
 else
  alm_tm->tm_min = 0xff;

 if (alm_en & S3C2410_RTCALM_HOUREN)
  BCD_TO_BIN(alm_tm->tm_hour);
 else
  alm_tm->tm_hour = 0xff;

 if (alm_en & S3C2410_RTCALM_DAYEN)
  BCD_TO_BIN(alm_tm->tm_mday);
 else
  alm_tm->tm_mday = 0xff;

 if (alm_en & S3C2410_RTCALM_MONEN) {
  BCD_TO_BIN(alm_tm->tm_mon);
  alm_tm->tm_mon -= 1;
 } else {
  alm_tm->tm_mon = 0xff;
 }

 if (alm_en & S3C2410_RTCALM_YEAREN)
  BCD_TO_BIN(alm_tm->tm_year);
 else
  alm_tm->tm_year = 0xffff;

 return 0;
}

static int s3c_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
 struct rtc_time *tm = &alrm->time;
 void __iomem *base = s3c_rtc_base;
 unsigned int alrm_en;

 pr_debug("s3c_rtc_setalarm: %d, %02x/%02x/%02x %02x.%02x.%02x\n",
   alrm->enabled,
   tm->tm_mday & 0xff, tm->tm_mon & 0xff, tm->tm_year & 0xff,
   tm->tm_hour & 0xff, tm->tm_min & 0xff, tm->tm_sec);

 alrm_en = readb(base + S3C2410_RTCALM) & S3C2410_RTCALM_ALMEN;
 writeb(0x00, base + S3C2410_RTCALM);

 if (tm->tm_sec < 60 && tm->tm_sec >= 0) {
  alrm_en |= S3C2410_RTCALM_SECEN;
  writeb(BIN2BCD(tm->tm_sec), base + S3C2410_ALMSEC);
 }

 if (tm->tm_min < 60 && tm->tm_min >= 0) {
  alrm_en |= S3C2410_RTCALM_MINEN;
  writeb(BIN2BCD(tm->tm_min), base + S3C2410_ALMMIN);
 }

 if (tm->tm_hour < 24 && tm->tm_hour >= 0) {
  alrm_en |= S3C2410_RTCALM_HOUREN;
  writeb(BIN2BCD(tm->tm_hour), base + S3C2410_ALMHOUR);
 }

 pr_debug("setting S3C2410_RTCALM to %08x\n", alrm_en);

 writeb(alrm_en, base + S3C2410_RTCALM);

 if (0) {
  alrm_en = readb(base + S3C2410_RTCALM);
  alrm_en &= ~S3C2410_RTCALM_ALMEN;
  writeb(alrm_en, base + S3C2410_RTCALM);
  disable_irq_wake(s3c_rtc_alarmno);
 }

 if (alrm->enabled)
  enable_irq_wake(s3c_rtc_alarmno);
 else
  disable_irq_wake(s3c_rtc_alarmno);

 return 0;
}

static int s3c_rtc_ioctl(struct device *dev,
    unsigned int cmd, unsigned long arg)
{
 unsigned int ret = -ENOIOCTLCMD;

 switch (cmd) {
 case RTC_AIE_OFF:
 case RTC_AIE_ON:
  s3c_rtc_setaie((cmd == RTC_AIE_ON) ? 1 : 0);
  ret = 0;
  break;

 case RTC_PIE_OFF:
 case RTC_PIE_ON:
  tick_count = 0;
  s3c_rtc_setpie((cmd == RTC_PIE_ON) ? 1 : 0);
  ret = 0;
  break;

 case RTC_IRQP_READ:
  ret = put_user(s3c_rtc_freq, (unsigned long __user *)arg);
  break;

 case RTC_IRQP_SET:
  /* check for power of 2 */

  if ((arg & (arg-1)) != 0 || arg < 1) {
   ret = -EINVAL;
   goto exit;
  }

  pr_debug("s3c2410_rtc: setting frequency %ld\n", arg);

  s3c_rtc_setfreq(arg);
  ret = 0;
  break;

 case RTC_UIE_ON:
 case RTC_UIE_OFF:
  ret = -EINVAL;
 }

 exit:
 return ret;
}

static int s3c_rtc_proc(struct device *dev, struct seq_file *seq)
{
 unsigned int ticnt = readb(s3c_rtc_base + S3C2410_TICNT);

 seq_printf(seq, "periodic_IRQ\t: %s\n",
       (ticnt & S3C2410_TICNT_ENABLE) ? "yes" : "no" );

 seq_printf(seq, "periodic_freq\t: %d\n", s3c_rtc_freq);

 return 0;
}

static int s3c_rtc_open(struct device *dev)
{
 struct platform_device *pdev = to_platform_device(dev);
 struct rtc_device *rtc_dev = platform_get_drvdata(pdev);
 int ret;

 ret = request_irq(s3c_rtc_alarmno, s3c_rtc_alarmirq,
     IRQF_DISABLED,  "s3c2410-rtc alarm", rtc_dev);

 if (ret) {
  dev_err(dev, "IRQ%d error %d\n", s3c_rtc_alarmno, ret);
  return ret;
 }

 ret = request_irq(s3c_rtc_tickno, s3c_rtc_tickirq,
     IRQF_DISABLED,  "s3c2410-rtc tick", rtc_dev);

 if (ret) {
  dev_err(dev, "IRQ%d error %d\n", s3c_rtc_tickno, ret);
  goto tick_err;
 }

 return ret;

 tick_err:
 free_irq(s3c_rtc_alarmno, rtc_dev);
 return ret;
}

static void s3c_rtc_release(struct device *dev)
{
 struct platform_device *pdev = to_platform_device(dev);
 struct rtc_device *rtc_dev = platform_get_drvdata(pdev);

 /* do not clear AIE here, it may be needed for wake */

 s3c_rtc_setpie(0);
 free_irq(s3c_rtc_alarmno, rtc_dev);
 free_irq(s3c_rtc_tickno, rtc_dev);
}

static const struct rtc_class_ops s3c_rtcops = {
 .open  = s3c_rtc_open,
 .release = s3c_rtc_release,
 .ioctl  = s3c_rtc_ioctl,
 .read_time = s3c_rtc_gettime,
 .set_time = s3c_rtc_settime,
 .read_alarm = s3c_rtc_getalarm,
 .set_alarm = s3c_rtc_setalarm,
 .proc         = s3c_rtc_proc,
};

static void s3c_rtc_enable(struct platform_device *pdev, int en)
{
 void __iomem *base = s3c_rtc_base;
 unsigned int tmp;

 if (s3c_rtc_base == NULL)
  return;

 if (!en) {
  tmp = readb(base + S3C2410_RTCCON);
  writeb(tmp & ~S3C2410_RTCCON_RTCEN, base + S3C2410_RTCCON);

  tmp = readb(base + S3C2410_TICNT);
  writeb(tmp & ~S3C2410_TICNT_ENABLE, base + S3C2410_TICNT);
 } else {
  /* re-enable the device, and check it is ok */

  if ((readb(base+S3C2410_RTCCON) & S3C2410_RTCCON_RTCEN) == 0){
   dev_info(&pdev->dev, "rtc disabled, re-enabling\n");

   tmp = readb(base + S3C2410_RTCCON);
   writeb(tmp|S3C2410_RTCCON_RTCEN, base+S3C2410_RTCCON);
  }

  if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CNTSEL)){
   dev_info(&pdev->dev, "removing RTCCON_CNTSEL\n");

   tmp = readb(base + S3C2410_RTCCON);
   writeb(tmp& ~S3C2410_RTCCON_CNTSEL, base+S3C2410_RTCCON);
  }

  if ((readb(base + S3C2410_RTCCON) & S3C2410_RTCCON_CLKRST)){
   dev_info(&pdev->dev, "removing RTCCON_CLKRST\n");

   tmp = readb(base + S3C2410_RTCCON);
   writeb(tmp & ~S3C2410_RTCCON_CLKRST, base+S3C2410_RTCCON);
  }
 }
}

static int s3c_rtc_remove(struct platform_device *dev)
{
 struct rtc_device *rtc = platform_get_drvdata(dev);

 platform_set_drvdata(dev, NULL);
 rtc_device_unregister(rtc);

 s3c_rtc_setpie(0);
 s3c_rtc_setaie(0);

 iounmap(s3c_rtc_base);
 release_resource(s3c_rtc_mem);
 kfree(s3c_rtc_mem);

 return 0;
}

static int s3c_rtc_probe(struct platform_device *pdev)
{
 struct rtc_device *rtc;
 struct resource *res;
 int ret;

 pr_debug("%s: probe=%p\n", __FUNCTION__, pdev);

 /* find the IRQs */

 s3c_rtc_tickno = platform_get_irq(pdev, 1);
 if (s3c_rtc_tickno < 0) {
  dev_err(&pdev->dev, "no irq for rtc tick\n");
  return -ENOENT;
 }

 s3c_rtc_alarmno = platform_get_irq(pdev, 0);
 if (s3c_rtc_alarmno < 0) {
  dev_err(&pdev->dev, "no irq for alarm\n");
  return -ENOENT;
 }

 pr_debug("s3c2410_rtc: tick irq %d, alarm irq %d\n",
   s3c_rtc_tickno, s3c_rtc_alarmno);

 /* get the memory region */

 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 if (res == NULL) {
  dev_err(&pdev->dev, "failed to get memory region resource\n");
  return -ENOENT;
 }

 s3c_rtc_mem = request_mem_region(res->start,
      res->end-res->start+1,
      pdev->name);

 if (s3c_rtc_mem == NULL) {
  dev_err(&pdev->dev, "failed to reserve memory region\n");
  ret = -ENOENT;
  goto err_nores;
 }

 s3c_rtc_base = ioremap(res->start, res->end - res->start + 1);
 if (s3c_rtc_base == NULL) {
  dev_err(&pdev->dev, "failed ioremap()\n");
  ret = -EINVAL;
  goto err_nomap;
 }

 /* check to see if everything is setup correctly */

 s3c_rtc_enable(pdev, 1);

  pr_debug("s3c2410_rtc: RTCCON=%02x\n",
   readb(s3c_rtc_base + S3C2410_RTCCON));

 s3c_rtc_setfreq(s3c_rtc_freq);

 /* register RTC and exit */

 rtc = rtc_device_register("s3c", &pdev->dev, &s3c_rtcops,
      THIS_MODULE);

 if (IS_ERR(rtc)) {
  dev_err(&pdev->dev, "cannot attach rtc\n");
  ret = PTR_ERR(rtc);
  goto err_nortc;
 }

 rtc->max_user_freq = 128;

 platform_set_drvdata(pdev, rtc);
 return 0;

 err_nortc:
 s3c_rtc_enable(pdev, 0);
 iounmap(s3c_rtc_base);

 err_nomap:
 release_resource(s3c_rtc_mem);

 err_nores:
 return ret;
}

#ifdef CONFIG_PM

/* RTC Power management control */

static struct timespec s3c_rtc_delta;

static int ticnt_save;

static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
 /* save TICNT for anyone using periodic interrupts */
 ticnt_save = readb(s3c_rtc_base + S3C2410_TICNT);
 s3c_rtc_enable(pdev, 0);
 return 0;
}

static int s3c_rtc_resume(struct platform_device *pdev)
{
 s3c_rtc_enable(pdev, 1);
 writeb(ticnt_save, s3c_rtc_base + S3C2410_TICNT);
 return 0;
}
#else
#define s3c_rtc_suspend NULL
#define s3c_rtc_resume  NULL
#endif

static struct platform_driver s3c2410_rtcdrv = {
 .probe  = s3c_rtc_probe,
 .remove  = s3c_rtc_remove,
 .suspend = s3c_rtc_suspend,
 .resume  = s3c_rtc_resume,
 .driver  = {
  .name = "s3c2410-rtc",
  .owner = THIS_MODULE,
 },
};

static char __initdata banner[] = "S3C24XX RTC, (c) 2004,2006 Simtec Electronics\n";

static int __init s3c_rtc_init(void)
{
 printk(banner);
 return platform_driver_register(&s3c2410_rtcdrv);
}

static void __exit s3c_rtc_exit(void)
{
 platform_driver_unregister(&s3c2410_rtcdrv);
}

module_init(s3c_rtc_init);
module_exit(s3c_rtc_exit);

MODULE_DESCRIPTION("Samsung S3C RTC Driver");
MODULE_AUTHOR("Ben Dooks ");
MODULE_LICENSE("GPL");