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rtc.c

/*
 *    Real Time Clock interface for Linux 
 *
 *    Copyright (C) 1996 Paul Gortmaker
 *
 *    This driver allows use of the real time clock (built into
 *    nearly all computers) from user space. It exports the /dev/rtc
 *    interface supporting various ioctl() and also the
 *    /proc/driver/rtc pseudo-file for status information.
 *
 *    The ioctls can be used to set the interrupt behaviour and
 *    generation rate from the RTC via IRQ 8. Then the /dev/rtc
 *    interface can be used to make use of these timer interrupts,
 *    be they interval or alarm based.
 *
 *    The /dev/rtc interface will block on reads until an interrupt
 *    has been received. If a RTC interrupt has already happened,
 *    it will output an unsigned long and then block. The output value
 *    contains the interrupt status in the low byte and the number of
 *    interrupts since the last read in the remaining high bytes. The 
 *    /dev/rtc interface can also be used with the select(2) call.
 *
 *    This program is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU General Public License
 *    as published by the Free Software Foundation; either version
 *    2 of the License, or (at your option) any later version.
 *
 *    Based on other minimal char device drivers, like Alan's
 *    watchdog, Ted's random, etc. etc.
 *
 *    1.07  Paul Gortmaker.
 *    1.08  Miquel van Smoorenburg: disallow certain things on the
 *          DEC Alpha as the CMOS clock is also used for other things.
 *    1.09  Nikita Schmidt: epoch support and some Alpha cleanup.
 *    1.09a Pete Zaitcev: Sun SPARC
 *    1.09b Jeff Garzik: Modularize, init cleanup
 *    1.09c Jeff Garzik: SMP cleanup
 *    1.10  Paul Barton-Davis: add support for async I/O
 *    1.10a Andrea Arcangeli: Alpha updates
 *    1.10b Andrew Morton: SMP lock fix
 *    1.10c Cesar Barros: SMP locking fixes and cleanup
 *    1.10d Paul Gortmaker: delete paranoia check in rtc_exit
 *    1.10e Maciej W. Rozycki: Handle DECstation's year weirdness.
 *    1.11  Takashi Iwai: Kernel access functions
 *                      rtc_register/rtc_unregister/rtc_control
 *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
 *    1.12  Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
 *          CONFIG_HPET_EMULATE_RTC
 *    1.12a Maciej W. Rozycki: Handle memory-mapped chips properly.
 *    1.12ac      Alan Cox: Allow read access to the day of week register
 */

#define RTC_VERSION           "1.12ac"

/*
 *    Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
 *    interrupts disabled. Due to the index-port/data-port (0x70/0x71)
 *    design of the RTC, we don't want two different things trying to
 *    get to it at once. (e.g. the periodic 11 min sync from time.c vs.
 *    this driver.)
 */

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/wait.h>
#include <linux/bcd.h>
#include <linux/delay.h>

#include <asm/current.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#ifdef CONFIG_X86
#include <asm/hpet.h>
#endif

#ifdef CONFIG_SPARC32
#include <linux/pci.h>
#include <asm/ebus.h>

static unsigned long rtc_port;
static int rtc_irq = PCI_IRQ_NONE;
#endif

#ifdef      CONFIG_HPET_RTC_IRQ
#undef      RTC_IRQ
#endif

#ifdef RTC_IRQ
static int rtc_has_irq = 1;
#endif

#ifndef CONFIG_HPET_EMULATE_RTC
#define is_hpet_enabled()                 0
#define hpet_set_alarm_time(hrs, min, sec)      0
#define hpet_set_periodic_freq(arg)             0
#define hpet_mask_rtc_irq_bit(arg)        0
#define hpet_set_rtc_irq_bit(arg)         0
#define hpet_rtc_timer_init()                   do { } while (0)
#define hpet_rtc_dropped_irq()                  0
#ifdef RTC_IRQ
static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
{
      return 0;
}
#endif
#else
extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
#endif

/*
 *    We sponge a minor off of the misc major. No need slurping
 *    up another valuable major dev number for this. If you add
 *    an ioctl, make sure you don't conflict with SPARC's RTC
 *    ioctls.
 */

static struct fasync_struct *rtc_async_queue;

static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);

#ifdef RTC_IRQ
static void rtc_dropped_irq(unsigned long data);

static DEFINE_TIMER(rtc_irq_timer, rtc_dropped_irq, 0, 0);
#endif

static ssize_t rtc_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos);

static int rtc_ioctl(struct inode *inode, struct file *file,
                 unsigned int cmd, unsigned long arg);

#ifdef RTC_IRQ
static unsigned int rtc_poll(struct file *file, poll_table *wait);
#endif

static void get_rtc_alm_time (struct rtc_time *alm_tm);
#ifdef RTC_IRQ
static void set_rtc_irq_bit_locked(unsigned char bit);
static void mask_rtc_irq_bit_locked(unsigned char bit);

static inline void set_rtc_irq_bit(unsigned char bit)
{
      spin_lock_irq(&rtc_lock);
      set_rtc_irq_bit_locked(bit);
      spin_unlock_irq(&rtc_lock);
}

static void mask_rtc_irq_bit(unsigned char bit)
{
      spin_lock_irq(&rtc_lock);
      mask_rtc_irq_bit_locked(bit);
      spin_unlock_irq(&rtc_lock);
}
#endif

#ifdef CONFIG_PROC_FS
static int rtc_proc_open(struct inode *inode, struct file *file);
#endif

/*
 *    Bits in rtc_status. (6 bits of room for future expansion)
 */

#define RTC_IS_OPEN           0x01  /* means /dev/rtc is in use   */
#define RTC_TIMER_ON          0x02  /* missed irq timer active    */

/*
 * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
 * protected by the big kernel lock. However, ioctl can still disable the timer
 * in rtc_status and then with del_timer after the interrupt has read
 * rtc_status but before mod_timer is called, which would then reenable the
 * timer (but you would need to have an awful timing before you'd trip on it)
 */
static unsigned long rtc_status = 0;      /* bitmapped status byte.     */
static unsigned long rtc_freq = 0;  /* Current periodic IRQ rate  */
static unsigned long rtc_irq_data = 0;    /* our output to the world    */
static unsigned long rtc_max_user_freq = 64; /* > this, need CAP_SYS_RESOURCE */

#ifdef RTC_IRQ
/*
 * rtc_task_lock nests inside rtc_lock.
 */
static DEFINE_SPINLOCK(rtc_task_lock);
static rtc_task_t *rtc_callback = NULL;
#endif

/*
 *    If this driver ever becomes modularised, it will be really nice
 *    to make the epoch retain its value across module reload...
 */

static unsigned long epoch = 1900;  /* year corresponding to 0x00 */

static const unsigned char days_in_mo[] = 
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/*
 * Returns true if a clock update is in progress
 */
static inline unsigned char rtc_is_updating(void)
{
      unsigned long flags;
      unsigned char uip;

      spin_lock_irqsave(&rtc_lock, flags);
      uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
      spin_unlock_irqrestore(&rtc_lock, flags);
      return uip;
}

#ifdef RTC_IRQ
/*
 *    A very tiny interrupt handler. It runs with IRQF_DISABLED set,
 *    but there is possibility of conflicting with the set_rtc_mmss()
 *    call (the rtc irq and the timer irq can easily run at the same
 *    time in two different CPUs). So we need to serialize
 *    accesses to the chip with the rtc_lock spinlock that each
 *    architecture should implement in the timer code.
 *    (See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
 */

irqreturn_t rtc_interrupt(int irq, void *dev_id)
{
      /*
       *    Can be an alarm interrupt, update complete interrupt,
       *    or a periodic interrupt. We store the status in the
       *    low byte and the number of interrupts received since
       *    the last read in the remainder of rtc_irq_data.
       */

      spin_lock (&rtc_lock);
      rtc_irq_data += 0x100;
      rtc_irq_data &= ~0xff;
      if (is_hpet_enabled()) {
            /*
             * In this case it is HPET RTC interrupt handler
             * calling us, with the interrupt information
             * passed as arg1, instead of irq.
             */
            rtc_irq_data |= (unsigned long)irq & 0xF0;
      } else {
            rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
      }

      if (rtc_status & RTC_TIMER_ON)
            mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);

      spin_unlock (&rtc_lock);

      /* Now do the rest of the actions */
      spin_lock(&rtc_task_lock);
      if (rtc_callback)
            rtc_callback->func(rtc_callback->private_data);
      spin_unlock(&rtc_task_lock);
      wake_up_interruptible(&rtc_wait);   

      kill_fasync (&rtc_async_queue, SIGIO, POLL_IN);

      return IRQ_HANDLED;
}
#endif

/*
 * sysctl-tuning infrastructure.
 */
static ctl_table rtc_table[] = {
      {
            .ctl_name   = CTL_UNNUMBERED,
            .procname   = "max-user-freq",
            .data       = &rtc_max_user_freq,
            .maxlen           = sizeof(int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec,
      },
      { .ctl_name = 0 }
};

static ctl_table rtc_root[] = {
      {
            .ctl_name   = CTL_UNNUMBERED,
            .procname   = "rtc",
            .mode       = 0555,
            .child            = rtc_table,
      },
      { .ctl_name = 0 }
};

static ctl_table dev_root[] = {
      {
            .ctl_name   = CTL_DEV,
            .procname   = "dev",
            .mode       = 0555,
            .child            = rtc_root,
      },
      { .ctl_name = 0 }
};

static struct ctl_table_header *sysctl_header;

static int __init init_sysctl(void)
{
    sysctl_header = register_sysctl_table(dev_root);
    return 0;
}

static void __exit cleanup_sysctl(void)
{
    unregister_sysctl_table(sysctl_header);
}

/*
 *    Now all the various file operations that we export.
 */

static ssize_t rtc_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
#ifndef RTC_IRQ
      return -EIO;
#else
      DECLARE_WAITQUEUE(wait, current);
      unsigned long data;
      ssize_t retval;
      
      if (rtc_has_irq == 0)
            return -EIO;

      /*
       * Historically this function used to assume that sizeof(unsigned long)
       * is the same in userspace and kernelspace.  This lead to problems
       * for configurations with multiple ABIs such a the MIPS o32 and 64
       * ABIs supported on the same kernel.  So now we support read of both
       * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
       * userspace ABI.
       */
      if (count != sizeof(unsigned int) && count !=  sizeof(unsigned long))
            return -EINVAL;

      add_wait_queue(&rtc_wait, &wait);

      do {
            /* First make it right. Then make it fast. Putting this whole
             * block within the parentheses of a while would be too
             * confusing. And no, xchg() is not the answer. */

            __set_current_state(TASK_INTERRUPTIBLE);
            
            spin_lock_irq (&rtc_lock);
            data = rtc_irq_data;
            rtc_irq_data = 0;
            spin_unlock_irq (&rtc_lock);

            if (data != 0)
                  break;

            if (file->f_flags & O_NONBLOCK) {
                  retval = -EAGAIN;
                  goto out;
            }
            if (signal_pending(current)) {
                  retval = -ERESTARTSYS;
                  goto out;
            }
            schedule();
      } while (1);

      if (count == sizeof(unsigned int))
            retval = put_user(data, (unsigned int __user *)buf) ?: sizeof(int);
      else
            retval = put_user(data, (unsigned long __user *)buf) ?: sizeof(long);
      if (!retval)
            retval = count;
 out:
      __set_current_state(TASK_RUNNING);
      remove_wait_queue(&rtc_wait, &wait);

      return retval;
#endif
}

static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel)
{
      struct rtc_time wtime; 

#ifdef RTC_IRQ
      if (rtc_has_irq == 0) {
            switch (cmd) {
            case RTC_AIE_OFF:
            case RTC_AIE_ON:
            case RTC_PIE_OFF:
            case RTC_PIE_ON:
            case RTC_UIE_OFF:
            case RTC_UIE_ON:
            case RTC_IRQP_READ:
            case RTC_IRQP_SET:
                  return -EINVAL;
            };
      }
#endif

      switch (cmd) {
#ifdef RTC_IRQ
      case RTC_AIE_OFF: /* Mask alarm int. enab. bit  */
      {
            mask_rtc_irq_bit(RTC_AIE);
            return 0;
      }
      case RTC_AIE_ON:  /* Allow alarm interrupts.    */
      {
            set_rtc_irq_bit(RTC_AIE);
            return 0;
      }
      case RTC_PIE_OFF: /* Mask periodic int. enab. bit     */
      {
            unsigned long flags; /* can be called from isr via rtc_control() */
            spin_lock_irqsave (&rtc_lock, flags);
            mask_rtc_irq_bit_locked(RTC_PIE);
            if (rtc_status & RTC_TIMER_ON) {
                  rtc_status &= ~RTC_TIMER_ON;
                  del_timer(&rtc_irq_timer);
            }
            spin_unlock_irqrestore (&rtc_lock, flags);
            return 0;
      }
      case RTC_PIE_ON:  /* Allow periodic ints        */
      {
            unsigned long flags; /* can be called from isr via rtc_control() */
            /*
             * We don't really want Joe User enabling more
             * than 64Hz of interrupts on a multi-user machine.
             */
            if (!kernel && (rtc_freq > rtc_max_user_freq) &&
                  (!capable(CAP_SYS_RESOURCE)))
                  return -EACCES;

            spin_lock_irqsave (&rtc_lock, flags);
            if (!(rtc_status & RTC_TIMER_ON)) {
                  mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq +
                              2*HZ/100);
                  rtc_status |= RTC_TIMER_ON;
            }
            set_rtc_irq_bit_locked(RTC_PIE);
            spin_unlock_irqrestore (&rtc_lock, flags);
            return 0;
      }
      case RTC_UIE_OFF: /* Mask ints from RTC updates.      */
      {
            mask_rtc_irq_bit(RTC_UIE);
            return 0;
      }
      case RTC_UIE_ON:  /* Allow ints for RTC updates.      */
      {
            set_rtc_irq_bit(RTC_UIE);
            return 0;
      }
#endif
      case RTC_ALM_READ:      /* Read the present alarm time */
      {
            /*
             * This returns a struct rtc_time. Reading >= 0xc0
             * means "don't care" or "match all". Only the tm_hour,
             * tm_min, and tm_sec values are filled in.
             */
            memset(&wtime, 0, sizeof(struct rtc_time));
            get_rtc_alm_time(&wtime);
            break; 
      }
      case RTC_ALM_SET: /* Store a time into the alarm */
      {
            /*
             * This expects a struct rtc_time. Writing 0xff means
             * "don't care" or "match all". Only the tm_hour,
             * tm_min and tm_sec are used.
             */
            unsigned char hrs, min, sec;
            struct rtc_time alm_tm;

            if (copy_from_user(&alm_tm, (struct rtc_time __user *)arg,
                           sizeof(struct rtc_time)))
                  return -EFAULT;

            hrs = alm_tm.tm_hour;
            min = alm_tm.tm_min;
            sec = alm_tm.tm_sec;

            spin_lock_irq(&rtc_lock);
            if (hpet_set_alarm_time(hrs, min, sec)) {
                  /*
                   * Fallthru and set alarm time in CMOS too,
                   * so that we will get proper value in RTC_ALM_READ
                   */
            }
            if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
                RTC_ALWAYS_BCD)
            {
                  if (sec < 60) BIN_TO_BCD(sec);
                  else sec = 0xff;

                  if (min < 60) BIN_TO_BCD(min);
                  else min = 0xff;

                  if (hrs < 24) BIN_TO_BCD(hrs);
                  else hrs = 0xff;
            }
            CMOS_WRITE(hrs, RTC_HOURS_ALARM);
            CMOS_WRITE(min, RTC_MINUTES_ALARM);
            CMOS_WRITE(sec, RTC_SECONDS_ALARM);
            spin_unlock_irq(&rtc_lock);

            return 0;
      }
      case RTC_RD_TIME: /* Read the time/date from RTC      */
      {
            memset(&wtime, 0, sizeof(struct rtc_time));
            rtc_get_rtc_time(&wtime);
            break;
      }
      case RTC_SET_TIME:      /* Set the RTC */
      {
            struct rtc_time rtc_tm;
            unsigned char mon, day, hrs, min, sec, leap_yr;
            unsigned char save_control, save_freq_select;
            unsigned int yrs;
#ifdef CONFIG_MACH_DECSTATION
            unsigned int real_yrs;
#endif

            if (!capable(CAP_SYS_TIME))
                  return -EACCES;

            if (copy_from_user(&rtc_tm, (struct rtc_time __user *)arg,
                           sizeof(struct rtc_time)))
                  return -EFAULT;

            yrs = rtc_tm.tm_year + 1900;
            mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
            day = rtc_tm.tm_mday;
            hrs = rtc_tm.tm_hour;
            min = rtc_tm.tm_min;
            sec = rtc_tm.tm_sec;

            if (yrs < 1970)
                  return -EINVAL;

            leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));

            if ((mon > 12) || (day == 0))
                  return -EINVAL;

            if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
                  return -EINVAL;
                  
            if ((hrs >= 24) || (min >= 60) || (sec >= 60))
                  return -EINVAL;

            if ((yrs -= epoch) > 255)    /* They are unsigned */
                  return -EINVAL;

            spin_lock_irq(&rtc_lock);
#ifdef CONFIG_MACH_DECSTATION
            real_yrs = yrs;
            yrs = 72;

            /*
             * We want to keep the year set to 73 until March
             * for non-leap years, so that Feb, 29th is handled
             * correctly.
             */
            if (!leap_yr && mon < 3) {
                  real_yrs--;
                  yrs = 73;
            }
#endif
            /* These limits and adjustments are independent of
             * whether the chip is in binary mode or not.
             */
            if (yrs > 169) {
                  spin_unlock_irq(&rtc_lock);
                  return -EINVAL;
            }
            if (yrs >= 100)
                  yrs -= 100;

            if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
                || RTC_ALWAYS_BCD) {
                  BIN_TO_BCD(sec);
                  BIN_TO_BCD(min);
                  BIN_TO_BCD(hrs);
                  BIN_TO_BCD(day);
                  BIN_TO_BCD(mon);
                  BIN_TO_BCD(yrs);
            }

            save_control = CMOS_READ(RTC_CONTROL);
            CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
            save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
            CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);

#ifdef CONFIG_MACH_DECSTATION
            CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
#endif
            CMOS_WRITE(yrs, RTC_YEAR);
            CMOS_WRITE(mon, RTC_MONTH);
            CMOS_WRITE(day, RTC_DAY_OF_MONTH);
            CMOS_WRITE(hrs, RTC_HOURS);
            CMOS_WRITE(min, RTC_MINUTES);
            CMOS_WRITE(sec, RTC_SECONDS);

            CMOS_WRITE(save_control, RTC_CONTROL);
            CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

            spin_unlock_irq(&rtc_lock);
            return 0;
      }
#ifdef RTC_IRQ
      case RTC_IRQP_READ:     /* Read the periodic IRQ rate.      */
      {
            return put_user(rtc_freq, (unsigned long __user *)arg);
      }
      case RTC_IRQP_SET:      /* Set periodic IRQ rate.     */
      {
            int tmp = 0;
            unsigned char val;
            unsigned long flags; /* can be called from isr via rtc_control() */

            /* 
             * The max we can do is 8192Hz.
             */
            if ((arg < 2) || (arg > 8192))
                  return -EINVAL;
            /*
             * We don't really want Joe User generating more
             * than 64Hz of interrupts on a multi-user machine.
             */
            if (!kernel && (arg > rtc_max_user_freq) && (!capable(CAP_SYS_RESOURCE)))
                  return -EACCES;

            while (arg > (1<<tmp))
                  tmp++;

            /*
             * Check that the input was really a power of 2.
             */
            if (arg != (1<<tmp))
                  return -EINVAL;

            spin_lock_irqsave(&rtc_lock, flags);
            if (hpet_set_periodic_freq(arg)) {
                  spin_unlock_irqrestore(&rtc_lock, flags);
                  return 0;
            }
            rtc_freq = arg;

            val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
            val |= (16 - tmp);
            CMOS_WRITE(val, RTC_FREQ_SELECT);
            spin_unlock_irqrestore(&rtc_lock, flags);
            return 0;
      }
#endif
      case RTC_EPOCH_READ:    /* Read the epoch.      */
      {
            return put_user (epoch, (unsigned long __user *)arg);
      }
      case RTC_EPOCH_SET:     /* Set the epoch. */
      {
            /* 
             * There were no RTC clocks before 1900.
             */
            if (arg < 1900)
                  return -EINVAL;

            if (!capable(CAP_SYS_TIME))
                  return -EACCES;

            epoch = arg;
            return 0;
      }
      default:
            return -ENOTTY;
      }
      return copy_to_user((void __user *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
}

static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
                 unsigned long arg)
{
      return rtc_do_ioctl(cmd, arg, 0);
}

/*
 *    We enforce only one user at a time here with the open/close.
 *    Also clear the previous interrupt data on an open, and clean
 *    up things on a close.
 */

/* We use rtc_lock to protect against concurrent opens. So the BKL is not
 * needed here. Or anywhere else in this driver. */
static int rtc_open(struct inode *inode, struct file *file)
{
      spin_lock_irq (&rtc_lock);

      if(rtc_status & RTC_IS_OPEN)
            goto out_busy;

      rtc_status |= RTC_IS_OPEN;

      rtc_irq_data = 0;
      spin_unlock_irq (&rtc_lock);
      return 0;

out_busy:
      spin_unlock_irq (&rtc_lock);
      return -EBUSY;
}

static int rtc_fasync (int fd, struct file *filp, int on)

{
      return fasync_helper (fd, filp, on, &rtc_async_queue);
}

static int rtc_release(struct inode *inode, struct file *file)
{
#ifdef RTC_IRQ
      unsigned char tmp;

      if (rtc_has_irq == 0)
            goto no_irq;

      /*
       * Turn off all interrupts once the device is no longer
       * in use, and clear the data.
       */

      spin_lock_irq(&rtc_lock);
      if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
            tmp = CMOS_READ(RTC_CONTROL);
            tmp &=  ~RTC_PIE;
            tmp &=  ~RTC_AIE;
            tmp &=  ~RTC_UIE;
            CMOS_WRITE(tmp, RTC_CONTROL);
            CMOS_READ(RTC_INTR_FLAGS);
      }
      if (rtc_status & RTC_TIMER_ON) {
            rtc_status &= ~RTC_TIMER_ON;
            del_timer(&rtc_irq_timer);
      }
      spin_unlock_irq(&rtc_lock);

      if (file->f_flags & FASYNC) {
            rtc_fasync (-1, file, 0);
      }
no_irq:
#endif

      spin_lock_irq (&rtc_lock);
      rtc_irq_data = 0;
      rtc_status &= ~RTC_IS_OPEN;
      spin_unlock_irq (&rtc_lock);
      return 0;
}

#ifdef RTC_IRQ
/* Called without the kernel lock - fine */
static unsigned int rtc_poll(struct file *file, poll_table *wait)
{
      unsigned long l;

      if (rtc_has_irq == 0)
            return 0;

      poll_wait(file, &rtc_wait, wait);

      spin_lock_irq (&rtc_lock);
      l = rtc_irq_data;
      spin_unlock_irq (&rtc_lock);

      if (l != 0)
            return POLLIN | POLLRDNORM;
      return 0;
}
#endif

/*
 * exported stuffs
 */

EXPORT_SYMBOL(rtc_register);
EXPORT_SYMBOL(rtc_unregister);
EXPORT_SYMBOL(rtc_control);

int rtc_register(rtc_task_t *task)
{
#ifndef RTC_IRQ
      return -EIO;
#else
      if (task == NULL || task->func == NULL)
            return -EINVAL;
      spin_lock_irq(&rtc_lock);
      if (rtc_status & RTC_IS_OPEN) {
            spin_unlock_irq(&rtc_lock);
            return -EBUSY;
      }
      spin_lock(&rtc_task_lock);
      if (rtc_callback) {
            spin_unlock(&rtc_task_lock);
            spin_unlock_irq(&rtc_lock);
            return -EBUSY;
      }
      rtc_status |= RTC_IS_OPEN;
      rtc_callback = task;
      spin_unlock(&rtc_task_lock);
      spin_unlock_irq(&rtc_lock);
      return 0;
#endif
}

int rtc_unregister(rtc_task_t *task)
{
#ifndef RTC_IRQ
      return -EIO;
#else
      unsigned char tmp;

      spin_lock_irq(&rtc_lock);
      spin_lock(&rtc_task_lock);
      if (rtc_callback != task) {
            spin_unlock(&rtc_task_lock);
            spin_unlock_irq(&rtc_lock);
            return -ENXIO;
      }
      rtc_callback = NULL;
      
      /* disable controls */
      if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
            tmp = CMOS_READ(RTC_CONTROL);
            tmp &= ~RTC_PIE;
            tmp &= ~RTC_AIE;
            tmp &= ~RTC_UIE;
            CMOS_WRITE(tmp, RTC_CONTROL);
            CMOS_READ(RTC_INTR_FLAGS);
      }
      if (rtc_status & RTC_TIMER_ON) {
            rtc_status &= ~RTC_TIMER_ON;
            del_timer(&rtc_irq_timer);
      }
      rtc_status &= ~RTC_IS_OPEN;
      spin_unlock(&rtc_task_lock);
      spin_unlock_irq(&rtc_lock);
      return 0;
#endif
}

int rtc_control(rtc_task_t *task, unsigned int cmd, unsigned long arg)
{
#ifndef RTC_IRQ
      return -EIO;
#else
      unsigned long flags;
      if (cmd != RTC_PIE_ON && cmd != RTC_PIE_OFF && cmd != RTC_IRQP_SET)
            return -EINVAL;
      spin_lock_irqsave(&rtc_task_lock, flags);
      if (rtc_callback != task) {
            spin_unlock_irqrestore(&rtc_task_lock, flags);
            return -ENXIO;
      }
      spin_unlock_irqrestore(&rtc_task_lock, flags);
      return rtc_do_ioctl(cmd, arg, 1);
#endif
}


/*
 *    The various file operations we support.
 */

static const struct file_operations rtc_fops = {
      .owner            = THIS_MODULE,
      .llseek           = no_llseek,
      .read       = rtc_read,
#ifdef RTC_IRQ
      .poll       = rtc_poll,
#endif
      .ioctl            = rtc_ioctl,
      .open       = rtc_open,
      .release    = rtc_release,
      .fasync           = rtc_fasync,
};

static struct miscdevice rtc_dev = {
      .minor            = RTC_MINOR,
      .name       = "rtc",
      .fops       = &rtc_fops,
};

#ifdef CONFIG_PROC_FS
static const struct file_operations rtc_proc_fops = {
      .owner = THIS_MODULE,
      .open = rtc_proc_open,
      .read  = seq_read,
      .llseek = seq_lseek,
      .release = single_release,
};
#endif

static resource_size_t rtc_size;

static struct resource * __init rtc_request_region(resource_size_t size)
{
      struct resource *r;

      if (RTC_IOMAPPED)
            r = request_region(RTC_PORT(0), size, "rtc");
      else
            r = request_mem_region(RTC_PORT(0), size, "rtc");

      if (r)
            rtc_size = size;

      return r;
}

static void rtc_release_region(void)
{
      if (RTC_IOMAPPED)
            release_region(RTC_PORT(0), rtc_size);
      else
            release_mem_region(RTC_PORT(0), rtc_size);
}

static int __init rtc_init(void)
{
#ifdef CONFIG_PROC_FS
      struct proc_dir_entry *ent;
#endif
#if defined(__alpha__) || defined(__mips__)
      unsigned int year, ctrl;
      char *guess = NULL;
#endif
#ifdef CONFIG_SPARC32
      struct linux_ebus *ebus;
      struct linux_ebus_device *edev;
#else
      void *r;
#ifdef RTC_IRQ
      irq_handler_t rtc_int_handler_ptr;
#endif
#endif

#ifdef CONFIG_SPARC32
      for_each_ebus(ebus) {
            for_each_ebusdev(edev, ebus) {
                  if(strcmp(edev->prom_node->name, "rtc") == 0) {
                        rtc_port = edev->resource[0].start;
                        rtc_irq = edev->irqs[0];
                        goto found;
                  }
            }
      }
      rtc_has_irq = 0;
      printk(KERN_ERR "rtc_init: no PC rtc found\n");
      return -EIO;

found:
      if (rtc_irq == PCI_IRQ_NONE) {
            rtc_has_irq = 0;
            goto no_irq;
      }

      /*
       * XXX Interrupt pin #7 in Espresso is shared between RTC and
       * PCI Slot 2 INTA# (and some INTx# in Slot 1).
       */
      if (request_irq(rtc_irq, rtc_interrupt, IRQF_SHARED, "rtc", (void *)&rtc_port)) {
            rtc_has_irq = 0;
            printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
            return -EIO;
      }
no_irq:
#else
      r = rtc_request_region(RTC_IO_EXTENT);

      /*
       * If we've already requested a smaller range (for example, because
       * PNPBIOS or ACPI told us how the device is configured), the request
       * above might fail because it's too big.
       *
       * If so, request just the range we actually use.
       */
      if (!r)
            r = rtc_request_region(RTC_IO_EXTENT_USED);
      if (!r) {
#ifdef RTC_IRQ
            rtc_has_irq = 0;
#endif
            printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
                   (long)(RTC_PORT(0)));
            return -EIO;
      }

#ifdef RTC_IRQ
      if (is_hpet_enabled()) {
            rtc_int_handler_ptr = hpet_rtc_interrupt;
      } else {
            rtc_int_handler_ptr = rtc_interrupt;
      }

      if(request_irq(RTC_IRQ, rtc_int_handler_ptr, IRQF_DISABLED, "rtc", NULL)) {
            /* Yeah right, seeing as irq 8 doesn't even hit the bus. */
            rtc_has_irq = 0;
            printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
            rtc_release_region();
            return -EIO;
      }
      hpet_rtc_timer_init();

#endif

#endif /* CONFIG_SPARC32 vs. others */

      if (misc_register(&rtc_dev)) {
#ifdef RTC_IRQ
            free_irq(RTC_IRQ, NULL);
            rtc_has_irq = 0;
#endif
            rtc_release_region();
            return -ENODEV;
      }

#ifdef CONFIG_PROC_FS
      ent = create_proc_entry("driver/rtc", 0, NULL);
      if (ent)
            ent->proc_fops = &rtc_proc_fops;
      else
            printk(KERN_WARNING "rtc: Failed to register with procfs.\n");
#endif

#if defined(__alpha__) || defined(__mips__)
      rtc_freq = HZ;
      
      /* Each operating system on an Alpha uses its own epoch.
         Let's try to guess which one we are using now. */
      
      if (rtc_is_updating() != 0)
            msleep(20);
      
      spin_lock_irq(&rtc_lock);
      year = CMOS_READ(RTC_YEAR);
      ctrl = CMOS_READ(RTC_CONTROL);
      spin_unlock_irq(&rtc_lock);
      
      if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
            BCD_TO_BIN(year);       /* This should never happen... */
      
      if (year < 20) {
            epoch = 2000;
            guess = "SRM (post-2000)";
      } else if (year >= 20 && year < 48) {
            epoch = 1980;
            guess = "ARC console";
      } else if (year >= 48 && year < 72) {
            epoch = 1952;
            guess = "Digital UNIX";
#if defined(__mips__)
      } else if (year >= 72 && year < 74) {
            epoch = 2000;
            guess = "Digital DECstation";
#else
      } else if (year >= 70) {
            epoch = 1900;
            guess = "Standard PC (1900)";
#endif
      }
      if (guess)
            printk(KERN_INFO "rtc: %s epoch (%lu) detected\n", guess, epoch);
#endif
#ifdef RTC_IRQ
      if (rtc_has_irq == 0)
            goto no_irq2;

      spin_lock_irq(&rtc_lock);
      rtc_freq = 1024;
      if (!hpet_set_periodic_freq(rtc_freq)) {
            /* Initialize periodic freq. to CMOS reset default, which is 1024Hz */
            CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06), RTC_FREQ_SELECT);
      }
      spin_unlock_irq(&rtc_lock);
no_irq2:
#endif

      (void) init_sysctl();

      printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");

      return 0;
}

static void __exit rtc_exit (void)
{
      cleanup_sysctl();
      remove_proc_entry ("driver/rtc", NULL);
      misc_deregister(&rtc_dev);

#ifdef CONFIG_SPARC32
      if (rtc_has_irq)
            free_irq (rtc_irq, &rtc_port);
#else
      rtc_release_region();
#ifdef RTC_IRQ
      if (rtc_has_irq)
            free_irq (RTC_IRQ, NULL);
#endif
#endif /* CONFIG_SPARC32 */
}

module_init(rtc_init);
module_exit(rtc_exit);

#ifdef RTC_IRQ
/*
 *    At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
 *    (usually during an IDE disk interrupt, with IRQ unmasking off)
 *    Since the interrupt handler doesn't get called, the IRQ status
 *    byte doesn't get read, and the RTC stops generating interrupts.
 *    A timer is set, and will call this function if/when that happens.
 *    To get it out of this stalled state, we just read the status.
 *    At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
 *    (You *really* shouldn't be trying to use a non-realtime system 
 *    for something that requires a steady > 1KHz signal anyways.)
 */

static void rtc_dropped_irq(unsigned long data)
{
      unsigned long freq;

      spin_lock_irq (&rtc_lock);

      if (hpet_rtc_dropped_irq()) {
            spin_unlock_irq(&rtc_lock);
            return;
      }

      /* Just in case someone disabled the timer from behind our back... */
      if (rtc_status & RTC_TIMER_ON)
            mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);

      rtc_irq_data += ((rtc_freq/HZ)<<8);
      rtc_irq_data &= ~0xff;
      rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);   /* restart */

      freq = rtc_freq;

      spin_unlock_irq(&rtc_lock);

      if (printk_ratelimit())
            printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n", freq);

      /* Now we have new data */
      wake_up_interruptible(&rtc_wait);

      kill_fasync (&rtc_async_queue, SIGIO, POLL_IN);
}
#endif

#ifdef CONFIG_PROC_FS
/*
 *    Info exported via "/proc/driver/rtc".
 */

static int rtc_proc_show(struct seq_file *seq, void *v)
{
#define YN(bit) ((ctrl & bit) ? "yes" : "no")
#define NY(bit) ((ctrl & bit) ? "no" : "yes")
      struct rtc_time tm;
      unsigned char batt, ctrl;
      unsigned long freq;

      spin_lock_irq(&rtc_lock);
      batt = CMOS_READ(RTC_VALID) & RTC_VRT;
      ctrl = CMOS_READ(RTC_CONTROL);
      freq = rtc_freq;
      spin_unlock_irq(&rtc_lock);


      rtc_get_rtc_time(&tm);

      /*
       * There is no way to tell if the luser has the RTC set for local
       * time or for Universal Standard Time (GMT). Probably local though.
       */
      seq_printf(seq,
               "rtc_time\t: %02d:%02d:%02d\n"
               "rtc_date\t: %04d-%02d-%02d\n"
               "rtc_epoch\t: %04lu\n",
               tm.tm_hour, tm.tm_min, tm.tm_sec,
               tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);

      get_rtc_alm_time(&tm);

      /*
       * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
       * match any value for that particular field. Values that are
       * greater than a valid time, but less than 0xc0 shouldn't appear.
       */
      seq_puts(seq, "alarm\t\t: ");
      if (tm.tm_hour <= 24)
            seq_printf(seq, "%02d:", tm.tm_hour);
      else
            seq_puts(seq, "**:");

      if (tm.tm_min <= 59)
            seq_printf(seq, "%02d:", tm.tm_min);
      else
            seq_puts(seq, "**:");

      if (tm.tm_sec <= 59)
            seq_printf(seq, "%02d\n", tm.tm_sec);
      else
            seq_puts(seq, "**\n");

      seq_printf(seq,
               "DST_enable\t: %s\n"
               "BCD\t\t: %s\n"
               "24hr\t\t: %s\n"
               "square_wave\t: %s\n"
               "alarm_IRQ\t: %s\n"
               "update_IRQ\t: %s\n"
               "periodic_IRQ\t: %s\n"
               "periodic_freq\t: %ld\n"
               "batt_status\t: %s\n",
               YN(RTC_DST_EN),
               NY(RTC_DM_BINARY),
               YN(RTC_24H),
               YN(RTC_SQWE),
               YN(RTC_AIE),
               YN(RTC_UIE),
               YN(RTC_PIE),
               freq,
               batt ? "okay" : "dead");

      return  0;
#undef YN
#undef NY
}

static int rtc_proc_open(struct inode *inode, struct file *file)
{
      return single_open(file, rtc_proc_show, NULL);
}
#endif

void rtc_get_rtc_time(struct rtc_time *rtc_tm)
{
      unsigned long uip_watchdog = jiffies, flags;
      unsigned char ctrl;
#ifdef CONFIG_MACH_DECSTATION
      unsigned int real_year;
#endif

      /*
       * read RTC once any update in progress is done. The update
       * can take just over 2ms. We wait 20ms. There is no need to
       * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
       * If you need to know *exactly* when a second has started, enable
       * periodic update complete interrupts, (via ioctl) and then 
       * immediately read /dev/rtc which will block until you get the IRQ.
       * Once the read clears, read the RTC time (again via ioctl). Easy.
       */

      while (rtc_is_updating() != 0 && jiffies - uip_watchdog < 2*HZ/100)
            cpu_relax();

      /*
       * Only the values that we read from the RTC are set. We leave
       * tm_wday, tm_yday and tm_isdst untouched. Note that while the
       * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
       * only updated by the RTC when initially set to a non-zero value.
       */
      spin_lock_irqsave(&rtc_lock, flags);
      rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
      rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
      rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
      rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
      rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
      rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
      /* Only set from 2.6.16 onwards */
      rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);

#ifdef CONFIG_MACH_DECSTATION
      real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
      ctrl = CMOS_READ(RTC_CONTROL);
      spin_unlock_irqrestore(&rtc_lock, flags);

      if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
      {
            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);
            BCD_TO_BIN(rtc_tm->tm_wday);
      }

#ifdef CONFIG_MACH_DECSTATION
      rtc_tm->tm_year += real_year - 72;
#endif

      /*
       * Account for differences between how the RTC uses the values
       * and how they are defined in a struct rtc_time;
       */
      if ((rtc_tm->tm_year += (epoch - 1900)) <= 69)
            rtc_tm->tm_year += 100;

      rtc_tm->tm_mon--;
}

static void get_rtc_alm_time(struct rtc_time *alm_tm)
{
      unsigned char ctrl;

      /*
       * Only the values that we read from the RTC are set. That
       * means only tm_hour, tm_min, and tm_sec.
       */
      spin_lock_irq(&rtc_lock);
      alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
      alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
      alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
      ctrl = CMOS_READ(RTC_CONTROL);
      spin_unlock_irq(&rtc_lock);

      if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
      {
            BCD_TO_BIN(alm_tm->tm_sec);
            BCD_TO_BIN(alm_tm->tm_min);
            BCD_TO_BIN(alm_tm->tm_hour);
      }
}

#ifdef RTC_IRQ
/*
 * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
 * Rumour has it that if you frob the interrupt enable/disable
 * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
 * ensure you actually start getting interrupts. Probably for
 * compatibility with older/broken chipset RTC implementations.
 * We also clear out any old irq data after an ioctl() that
 * meddles with the interrupt enable/disable bits.
 */

static void mask_rtc_irq_bit_locked(unsigned char bit)
{
      unsigned char val;

      if (hpet_mask_rtc_irq_bit(bit))
            return;
      val = CMOS_READ(RTC_CONTROL);
      val &=  ~bit;
      CMOS_WRITE(val, RTC_CONTROL);
      CMOS_READ(RTC_INTR_FLAGS);

      rtc_irq_data = 0;
}

static void set_rtc_irq_bit_locked(unsigned char bit)
{
      unsigned char val;

      if (hpet_set_rtc_irq_bit(bit))
            return;
      val = CMOS_READ(RTC_CONTROL);
      val |= bit;
      CMOS_WRITE(val, RTC_CONTROL);
      CMOS_READ(RTC_INTR_FLAGS);

      rtc_irq_data = 0;
}
#endif

MODULE_AUTHOR("Paul Gortmaker");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(RTC_MINOR);

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