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time.c

/* time.c: UltraSparc timer and TOD clock support.
 *
 * Copyright (C) 1997, 2008 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1998 Eddie C. Dost   (ecd@skynet.be)
 *
 * Based largely on code which is:
 *
 * Copyright (C) 1996 Thomas K. Dyas (tdyas@eden.rutgers.edu)
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/mc146818rtc.h>
#include <linux/delay.h>
#include <linux/profile.h>
#include <linux/bcd.h>
#include <linux/jiffies.h>
#include <linux/cpufreq.h>
#include <linux/percpu.h>
#include <linux/miscdevice.h>
#include <linux/rtc.h>
#include <linux/kernel_stat.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/of_device.h>

#include <asm/oplib.h>
#include <asm/mostek.h>
#include <asm/timer.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/starfire.h>
#include <asm/smp.h>
#include <asm/sections.h>
#include <asm/cpudata.h>
#include <asm/uaccess.h>
#include <asm/irq_regs.h>

#include "entry.h"

DEFINE_SPINLOCK(mostek_lock);
DEFINE_SPINLOCK(rtc_lock);
void __iomem *mstk48t02_regs = NULL;
#ifdef CONFIG_PCI
unsigned long ds1287_regs = 0UL;
static void __iomem *bq4802_regs;
#endif

static void __iomem *mstk48t08_regs;
static void __iomem *mstk48t59_regs;

static int set_rtc_mmss(unsigned long);

#define TICK_PRIV_BIT   (1UL << 63)
#define TICKCMP_IRQ_BIT (1UL << 63)

#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
      unsigned long pc = instruction_pointer(regs);

      if (in_lock_functions(pc))
            return regs->u_regs[UREG_RETPC];
      return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif

static void tick_disable_protection(void)
{
      /* Set things up so user can access tick register for profiling
       * purposes.  Also workaround BB_ERRATA_1 by doing a dummy
       * read back of %tick after writing it.
       */
      __asm__ __volatile__(
      "     ba,pt %%xcc, 1f\n"
      "      nop\n"
      "     .align      64\n"
      "1:   rd    %%tick, %%g2\n"
      "     add   %%g2, 6, %%g2\n"
      "     andn  %%g2, %0, %%g2\n"
      "     wrpr  %%g2, 0, %%tick\n"
      "     rdpr  %%tick, %%g0"
      : /* no outputs */
      : "r" (TICK_PRIV_BIT)
      : "g2");
}

static void tick_disable_irq(void)
{
      __asm__ __volatile__(
      "     ba,pt %%xcc, 1f\n"
      "      nop\n"
      "     .align      64\n"
      "1:   wr    %0, 0x0, %%tick_cmpr\n"
      "     rd    %%tick_cmpr, %%g0"
      : /* no outputs */
      : "r" (TICKCMP_IRQ_BIT));
}

static void tick_init_tick(void)
{
      tick_disable_protection();
      tick_disable_irq();
}

static unsigned long tick_get_tick(void)
{
      unsigned long ret;

      __asm__ __volatile__("rd      %%tick, %0\n\t"
                       "mov   %0, %0"
                       : "=r" (ret));

      return ret & ~TICK_PRIV_BIT;
}

static int tick_add_compare(unsigned long adj)
{
      unsigned long orig_tick, new_tick, new_compare;

      __asm__ __volatile__("rd      %%tick, %0"
                       : "=r" (orig_tick));

      orig_tick &= ~TICKCMP_IRQ_BIT;

      /* Workaround for Spitfire Errata (#54 I think??), I discovered
       * this via Sun BugID 4008234, mentioned in Solaris-2.5.1 patch
       * number 103640.
       *
       * On Blackbird writes to %tick_cmpr can fail, the
       * workaround seems to be to execute the wr instruction
       * at the start of an I-cache line, and perform a dummy
       * read back from %tick_cmpr right after writing to it. -DaveM
       */
      __asm__ __volatile__("ba,pt   %%xcc, 1f\n\t"
                       " add  %1, %2, %0\n\t"
                       ".align      64\n"
                       "1:\n\t"
                       "wr    %0, 0, %%tick_cmpr\n\t"
                       "rd    %%tick_cmpr, %%g0\n\t"
                       : "=r" (new_compare)
                       : "r" (orig_tick), "r" (adj));

      __asm__ __volatile__("rd      %%tick, %0"
                       : "=r" (new_tick));
      new_tick &= ~TICKCMP_IRQ_BIT;

      return ((long)(new_tick - (orig_tick+adj))) > 0L;
}

static unsigned long tick_add_tick(unsigned long adj)
{
      unsigned long new_tick;

      /* Also need to handle Blackbird bug here too. */
      __asm__ __volatile__("rd      %%tick, %0\n\t"
                       "add   %0, %1, %0\n\t"
                       "wrpr  %0, 0, %%tick\n\t"
                       : "=&r" (new_tick)
                       : "r" (adj));

      return new_tick;
}

static struct sparc64_tick_ops tick_operations __read_mostly = {
      .name       =     "tick",
      .init_tick  =     tick_init_tick,
      .disable_irq      =     tick_disable_irq,
      .get_tick   =     tick_get_tick,
      .add_tick   =     tick_add_tick,
      .add_compare      =     tick_add_compare,
      .softint_mask     =     1UL << 0,
};

struct sparc64_tick_ops *tick_ops __read_mostly = &tick_operations;

static void stick_disable_irq(void)
{
      __asm__ __volatile__(
      "wr   %0, 0x0, %%asr25"
      : /* no outputs */
      : "r" (TICKCMP_IRQ_BIT));
}

static void stick_init_tick(void)
{
      /* Writes to the %tick and %stick register are not
       * allowed on sun4v.  The Hypervisor controls that
       * bit, per-strand.
       */
      if (tlb_type != hypervisor) {
            tick_disable_protection();
            tick_disable_irq();

            /* Let the user get at STICK too. */
            __asm__ __volatile__(
            "     rd    %%asr24, %%g2\n"
            "     andn  %%g2, %0, %%g2\n"
            "     wr    %%g2, 0, %%asr24"
            : /* no outputs */
            : "r" (TICK_PRIV_BIT)
            : "g1", "g2");
      }

      stick_disable_irq();
}

static unsigned long stick_get_tick(void)
{
      unsigned long ret;

      __asm__ __volatile__("rd      %%asr24, %0"
                       : "=r" (ret));

      return ret & ~TICK_PRIV_BIT;
}

static unsigned long stick_add_tick(unsigned long adj)
{
      unsigned long new_tick;

      __asm__ __volatile__("rd      %%asr24, %0\n\t"
                       "add   %0, %1, %0\n\t"
                       "wr    %0, 0, %%asr24\n\t"
                       : "=&r" (new_tick)
                       : "r" (adj));

      return new_tick;
}

static int stick_add_compare(unsigned long adj)
{
      unsigned long orig_tick, new_tick;

      __asm__ __volatile__("rd      %%asr24, %0"
                       : "=r" (orig_tick));
      orig_tick &= ~TICKCMP_IRQ_BIT;

      __asm__ __volatile__("wr      %0, 0, %%asr25"
                       : /* no outputs */
                       : "r" (orig_tick + adj));

      __asm__ __volatile__("rd      %%asr24, %0"
                       : "=r" (new_tick));
      new_tick &= ~TICKCMP_IRQ_BIT;

      return ((long)(new_tick - (orig_tick+adj))) > 0L;
}

static struct sparc64_tick_ops stick_operations __read_mostly = {
      .name       =     "stick",
      .init_tick  =     stick_init_tick,
      .disable_irq      =     stick_disable_irq,
      .get_tick   =     stick_get_tick,
      .add_tick   =     stick_add_tick,
      .add_compare      =     stick_add_compare,
      .softint_mask     =     1UL << 16,
};

/* On Hummingbird the STICK/STICK_CMPR register is implemented
 * in I/O space.  There are two 64-bit registers each, the
 * first holds the low 32-bits of the value and the second holds
 * the high 32-bits.
 *
 * Since STICK is constantly updating, we have to access it carefully.
 *
 * The sequence we use to read is:
 * 1) read high
 * 2) read low
 * 3) read high again, if it rolled re-read both low and high again.
 *
 * Writing STICK safely is also tricky:
 * 1) write low to zero
 * 2) write high
 * 3) write low
 */
#define HBIRD_STICKCMP_ADDR   0x1fe0000f060UL
#define HBIRD_STICK_ADDR      0x1fe0000f070UL

static unsigned long __hbird_read_stick(void)
{
      unsigned long ret, tmp1, tmp2, tmp3;
      unsigned long addr = HBIRD_STICK_ADDR+8;

      __asm__ __volatile__("ldxa    [%1] %5, %2\n"
                       "1:\n\t"
                       "sub   %1, 0x8, %1\n\t"
                       "ldxa  [%1] %5, %3\n\t"
                       "add   %1, 0x8, %1\n\t"
                       "ldxa  [%1] %5, %4\n\t"
                       "cmp   %4, %2\n\t"
                       "bne,a,pn    %%xcc, 1b\n\t"
                       " mov  %4, %2\n\t"
                       "sllx  %4, 32, %4\n\t"
                       "or    %3, %4, %0\n\t"
                       : "=&r" (ret), "=&r" (addr),
                         "=&r" (tmp1), "=&r" (tmp2), "=&r" (tmp3)
                       : "i" (ASI_PHYS_BYPASS_EC_E), "1" (addr));

      return ret;
}

static void __hbird_write_stick(unsigned long val)
{
      unsigned long low = (val & 0xffffffffUL);
      unsigned long high = (val >> 32UL);
      unsigned long addr = HBIRD_STICK_ADDR;

      __asm__ __volatile__("stxa    %%g0, [%0] %4\n\t"
                       "add   %0, 0x8, %0\n\t"
                       "stxa  %3, [%0] %4\n\t"
                       "sub   %0, 0x8, %0\n\t"
                       "stxa  %2, [%0] %4"
                       : "=&r" (addr)
                       : "0" (addr), "r" (low), "r" (high),
                         "i" (ASI_PHYS_BYPASS_EC_E));
}

static void __hbird_write_compare(unsigned long val)
{
      unsigned long low = (val & 0xffffffffUL);
      unsigned long high = (val >> 32UL);
      unsigned long addr = HBIRD_STICKCMP_ADDR + 0x8UL;

      __asm__ __volatile__("stxa    %3, [%0] %4\n\t"
                       "sub   %0, 0x8, %0\n\t"
                       "stxa  %2, [%0] %4"
                       : "=&r" (addr)
                       : "0" (addr), "r" (low), "r" (high),
                         "i" (ASI_PHYS_BYPASS_EC_E));
}

static void hbtick_disable_irq(void)
{
      __hbird_write_compare(TICKCMP_IRQ_BIT);
}

static void hbtick_init_tick(void)
{
      tick_disable_protection();

      /* XXX This seems to be necessary to 'jumpstart' Hummingbird
       * XXX into actually sending STICK interrupts.  I think because
       * XXX of how we store %tick_cmpr in head.S this somehow resets the
       * XXX {TICK + STICK} interrupt mux.  -DaveM
       */
      __hbird_write_stick(__hbird_read_stick());

      hbtick_disable_irq();
}

static unsigned long hbtick_get_tick(void)
{
      return __hbird_read_stick() & ~TICK_PRIV_BIT;
}

static unsigned long hbtick_add_tick(unsigned long adj)
{
      unsigned long val;

      val = __hbird_read_stick() + adj;
      __hbird_write_stick(val);

      return val;
}

static int hbtick_add_compare(unsigned long adj)
{
      unsigned long val = __hbird_read_stick();
      unsigned long val2;

      val &= ~TICKCMP_IRQ_BIT;
      val += adj;
      __hbird_write_compare(val);

      val2 = __hbird_read_stick() & ~TICKCMP_IRQ_BIT;

      return ((long)(val2 - val)) > 0L;
}

static struct sparc64_tick_ops hbtick_operations __read_mostly = {
      .name       =     "hbtick",
      .init_tick  =     hbtick_init_tick,
      .disable_irq      =     hbtick_disable_irq,
      .get_tick   =     hbtick_get_tick,
      .add_tick   =     hbtick_add_tick,
      .add_compare      =     hbtick_add_compare,
      .softint_mask     =     1UL << 0,
};

static unsigned long timer_ticks_per_nsec_quotient __read_mostly;

int update_persistent_clock(struct timespec now)
{
      return set_rtc_mmss(now.tv_sec);
}

/* Kick start a stopped clock (procedure from the Sun NVRAM/hostid FAQ). */
static void __init kick_start_clock(void)
{
      void __iomem *regs = mstk48t02_regs;
      u8 sec, tmp;
      int i, count;

      prom_printf("CLOCK: Clock was stopped. Kick start ");

      spin_lock_irq(&mostek_lock);

      /* Turn on the kick start bit to start the oscillator. */
      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp |= MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);
      tmp = mostek_read(regs + MOSTEK_SEC);
      tmp &= ~MSTK_STOP;
      mostek_write(regs + MOSTEK_SEC, tmp);
      tmp = mostek_read(regs + MOSTEK_HOUR);
      tmp |= MSTK_KICK_START;
      mostek_write(regs + MOSTEK_HOUR, tmp);
      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp &= ~MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);

      spin_unlock_irq(&mostek_lock);

      /* Delay to allow the clock oscillator to start. */
      sec = MSTK_REG_SEC(regs);
      for (i = 0; i < 3; i++) {
            while (sec == MSTK_REG_SEC(regs))
                  for (count = 0; count < 100000; count++)
                        /* nothing */ ;
            prom_printf(".");
            sec = MSTK_REG_SEC(regs);
      }
      prom_printf("\n");

      spin_lock_irq(&mostek_lock);

      /* Turn off kick start and set a "valid" time and date. */
      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp |= MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);
      tmp = mostek_read(regs + MOSTEK_HOUR);
      tmp &= ~MSTK_KICK_START;
      mostek_write(regs + MOSTEK_HOUR, tmp);
      MSTK_SET_REG_SEC(regs,0);
      MSTK_SET_REG_MIN(regs,0);
      MSTK_SET_REG_HOUR(regs,0);
      MSTK_SET_REG_DOW(regs,5);
      MSTK_SET_REG_DOM(regs,1);
      MSTK_SET_REG_MONTH(regs,8);
      MSTK_SET_REG_YEAR(regs,1996 - MSTK_YEAR_ZERO);
      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp &= ~MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);

      spin_unlock_irq(&mostek_lock);

      /* Ensure the kick start bit is off. If it isn't, turn it off. */
      while (mostek_read(regs + MOSTEK_HOUR) & MSTK_KICK_START) {
            prom_printf("CLOCK: Kick start still on!\n");

            spin_lock_irq(&mostek_lock);

            tmp = mostek_read(regs + MOSTEK_CREG);
            tmp |= MSTK_CREG_WRITE;
            mostek_write(regs + MOSTEK_CREG, tmp);

            tmp = mostek_read(regs + MOSTEK_HOUR);
            tmp &= ~MSTK_KICK_START;
            mostek_write(regs + MOSTEK_HOUR, tmp);

            tmp = mostek_read(regs + MOSTEK_CREG);
            tmp &= ~MSTK_CREG_WRITE;
            mostek_write(regs + MOSTEK_CREG, tmp);

            spin_unlock_irq(&mostek_lock);
      }

      prom_printf("CLOCK: Kick start procedure successful.\n");
}

/* Return nonzero if the clock chip battery is low. */
static int __init has_low_battery(void)
{
      void __iomem *regs = mstk48t02_regs;
      u8 data1, data2;

      spin_lock_irq(&mostek_lock);

      data1 = mostek_read(regs + MOSTEK_EEPROM);      /* Read some data. */
      mostek_write(regs + MOSTEK_EEPROM, ~data1);     /* Write back the complement. */
      data2 = mostek_read(regs + MOSTEK_EEPROM);      /* Read back the complement. */
      mostek_write(regs + MOSTEK_EEPROM, data1);      /* Restore original value. */

      spin_unlock_irq(&mostek_lock);

      return (data1 == data2);      /* Was the write blocked? */
}

static void __init mostek_set_system_time(void __iomem *mregs)
{
      unsigned int year, mon, day, hour, min, sec;
      u8 tmp;

      spin_lock_irq(&mostek_lock);

      /* Traditional Mostek chip. */
      tmp = mostek_read(mregs + MOSTEK_CREG);
      tmp |= MSTK_CREG_READ;
      mostek_write(mregs + MOSTEK_CREG, tmp);

      sec = MSTK_REG_SEC(mregs);
      min = MSTK_REG_MIN(mregs);
      hour = MSTK_REG_HOUR(mregs);
      day = MSTK_REG_DOM(mregs);
      mon = MSTK_REG_MONTH(mregs);
      year = MSTK_CVT_YEAR( MSTK_REG_YEAR(mregs) );

      xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
      xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
      set_normalized_timespec(&wall_to_monotonic,
                              -xtime.tv_sec, -xtime.tv_nsec);

      tmp = mostek_read(mregs + MOSTEK_CREG);
      tmp &= ~MSTK_CREG_READ;
      mostek_write(mregs + MOSTEK_CREG, tmp);

      spin_unlock_irq(&mostek_lock);
}

/* Probe for the real time clock chip. */
static void __init set_system_time(void)
{
      unsigned int year, mon, day, hour, min, sec;
      void __iomem *mregs = mstk48t02_regs;
#ifdef CONFIG_PCI
      unsigned long dregs = ds1287_regs;
      void __iomem *bregs = bq4802_regs;
#else
      unsigned long dregs = 0UL;
      void __iomem *bregs = 0UL;
#endif

      if (!mregs && !dregs && !bregs) {
            prom_printf("Something wrong, clock regs not mapped yet.\n");
            prom_halt();
      }           

      if (mregs) {
            mostek_set_system_time(mregs);
            return;
      }

      if (bregs) {
            unsigned char val = readb(bregs + 0x0e);
            unsigned int century;

            /* BQ4802 RTC chip. */

            writeb(val | 0x08, bregs + 0x0e);

            sec  = readb(bregs + 0x00);
            min  = readb(bregs + 0x02);
            hour = readb(bregs + 0x04);
            day  = readb(bregs + 0x06);
            mon  = readb(bregs + 0x09);
            year = readb(bregs + 0x0a);
            century = readb(bregs + 0x0f);

            writeb(val, bregs + 0x0e);

            BCD_TO_BIN(sec);
            BCD_TO_BIN(min);
            BCD_TO_BIN(hour);
            BCD_TO_BIN(day);
            BCD_TO_BIN(mon);
            BCD_TO_BIN(year);
            BCD_TO_BIN(century);

            year += (century * 100);
      } else {
            /* Dallas 12887 RTC chip. */

            do {
                  sec  = CMOS_READ(RTC_SECONDS);
                  min  = CMOS_READ(RTC_MINUTES);
                  hour = CMOS_READ(RTC_HOURS);
                  day  = CMOS_READ(RTC_DAY_OF_MONTH);
                  mon  = CMOS_READ(RTC_MONTH);
                  year = CMOS_READ(RTC_YEAR);
            } while (sec != CMOS_READ(RTC_SECONDS));

            if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
                  BCD_TO_BIN(sec);
                  BCD_TO_BIN(min);
                  BCD_TO_BIN(hour);
                  BCD_TO_BIN(day);
                  BCD_TO_BIN(mon);
                  BCD_TO_BIN(year);
            }
            if ((year += 1900) < 1970)
                  year += 100;
      }

      xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
      xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
      set_normalized_timespec(&wall_to_monotonic,
                              -xtime.tv_sec, -xtime.tv_nsec);
}

/* davem suggests we keep this within the 4M locked kernel image */
static u32 starfire_get_time(void)
{
      static char obp_gettod[32];
      static u32 unix_tod;

      sprintf(obp_gettod, "h# %08x unix-gettod",
            (unsigned int) (long) &unix_tod);
      prom_feval(obp_gettod);

      return unix_tod;
}

static int starfire_set_time(u32 val)
{
      /* Do nothing, time is set using the service processor
       * console on this platform.
       */
      return 0;
}

static u32 hypervisor_get_time(void)
{
      unsigned long ret, time;
      int retries = 10000;

retry:
      ret = sun4v_tod_get(&time);
      if (ret == HV_EOK)
            return time;
      if (ret == HV_EWOULDBLOCK) {
            if (--retries > 0) {
                  udelay(100);
                  goto retry;
            }
            printk(KERN_WARNING "SUN4V: tod_get() timed out.\n");
            return 0;
      }
      printk(KERN_WARNING "SUN4V: tod_get() not supported.\n");
      return 0;
}

static int hypervisor_set_time(u32 secs)
{
      unsigned long ret;
      int retries = 10000;

retry:
      ret = sun4v_tod_set(secs);
      if (ret == HV_EOK)
            return 0;
      if (ret == HV_EWOULDBLOCK) {
            if (--retries > 0) {
                  udelay(100);
                  goto retry;
            }
            printk(KERN_WARNING "SUN4V: tod_set() timed out.\n");
            return -EAGAIN;
      }
      printk(KERN_WARNING "SUN4V: tod_set() not supported.\n");
      return -EOPNOTSUPP;
}

static int __init clock_model_matches(const char *model)
{
      if (strcmp(model, "mk48t02") &&
          strcmp(model, "mk48t08") &&
          strcmp(model, "mk48t59") &&
          strcmp(model, "m5819") &&
          strcmp(model, "m5819p") &&
          strcmp(model, "m5823") &&
          strcmp(model, "ds1287") &&
          strcmp(model, "bq4802"))
            return 0;

      return 1;
}

static int __devinit clock_probe(struct of_device *op, const struct of_device_id *match)
{
      struct device_node *dp = op->node;
      const char *model = of_get_property(dp, "model", NULL);
      const char *compat = of_get_property(dp, "compatible", NULL);
      unsigned long size, flags;
      void __iomem *regs;

      if (!model)
            model = compat;

      if (!model || !clock_model_matches(model))
            return -ENODEV;

      /* On an Enterprise system there can be multiple mostek clocks.
       * We should only match the one that is on the central FHC bus.
       */
      if (!strcmp(dp->parent->name, "fhc") &&
          strcmp(dp->parent->parent->name, "central") != 0)
            return -ENODEV;

      size = (op->resource[0].end - op->resource[0].start) + 1;
      regs = of_ioremap(&op->resource[0], 0, size, "clock");
      if (!regs)
            return -ENOMEM;

#ifdef CONFIG_PCI
      if (!strcmp(model, "ds1287") ||
          !strcmp(model, "m5819") ||
          !strcmp(model, "m5819p") ||
          !strcmp(model, "m5823")) {
            ds1287_regs = (unsigned long) regs;
      } else if (!strcmp(model, "bq4802")) {
            bq4802_regs = regs;
      } else
#endif
      if (model[5] == '0' && model[6] == '2') {
            mstk48t02_regs = regs;
      } else if(model[5] == '0' && model[6] == '8') {
            mstk48t08_regs = regs;
            mstk48t02_regs = mstk48t08_regs + MOSTEK_48T08_48T02;
      } else {
            mstk48t59_regs = regs;
            mstk48t02_regs = mstk48t59_regs + MOSTEK_48T59_48T02;
      }

      printk(KERN_INFO "%s: Clock regs at %p\n", dp->full_name, regs);

      local_irq_save(flags);

      if (mstk48t02_regs != NULL) {
            /* Report a low battery voltage condition. */
            if (has_low_battery())
                  prom_printf("NVRAM: Low battery voltage!\n");

            /* Kick start the clock if it is completely stopped. */
            if (mostek_read(mstk48t02_regs + MOSTEK_SEC) & MSTK_STOP)
                  kick_start_clock();
      }

      set_system_time();
      
      local_irq_restore(flags);

      return 0;
}

static struct of_device_id clock_match[] = {
      {
            .name = "eeprom",
      },
      {
            .name = "rtc",
      },
      {},
};

static struct of_platform_driver clock_driver = {
      .match_table      = clock_match,
      .probe            = clock_probe,
      .driver           = {
            .name = "clock",
      },
};

static int __init clock_init(void)
{
      if (this_is_starfire) {
            xtime.tv_sec = starfire_get_time();
            xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
            set_normalized_timespec(&wall_to_monotonic,
                                    -xtime.tv_sec, -xtime.tv_nsec);
            return 0;
      }
      if (tlb_type == hypervisor) {
            xtime.tv_sec = hypervisor_get_time();
            xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
            set_normalized_timespec(&wall_to_monotonic,
                                    -xtime.tv_sec, -xtime.tv_nsec);
            return 0;
      }

      return of_register_driver(&clock_driver, &of_platform_bus_type);
}

/* Must be after subsys_initcall() so that busses are probed.  Must
 * be before device_initcall() because things like the RTC driver
 * need to see the clock registers.
 */
fs_initcall(clock_init);

/* This is gets the master TICK_INT timer going. */
static unsigned long sparc64_init_timers(void)
{
      struct device_node *dp;
      unsigned long clock;

      dp = of_find_node_by_path("/");
      if (tlb_type == spitfire) {
            unsigned long ver, manuf, impl;

            __asm__ __volatile__ ("rdpr %%ver, %0"
                              : "=&r" (ver));
            manuf = ((ver >> 48) & 0xffff);
            impl = ((ver >> 32) & 0xffff);
            if (manuf == 0x17 && impl == 0x13) {
                  /* Hummingbird, aka Ultra-IIe */
                  tick_ops = &hbtick_operations;
                  clock = of_getintprop_default(dp, "stick-frequency", 0);
            } else {
                  tick_ops = &tick_operations;
                  clock = local_cpu_data().clock_tick;
            }
      } else {
            tick_ops = &stick_operations;
            clock = of_getintprop_default(dp, "stick-frequency", 0);
      }

      return clock;
}

struct freq_table {
      unsigned long clock_tick_ref;
      unsigned int ref_freq;
};
static DEFINE_PER_CPU(struct freq_table, sparc64_freq_table) = { 0, 0 };

unsigned long sparc64_get_clock_tick(unsigned int cpu)
{
      struct freq_table *ft = &per_cpu(sparc64_freq_table, cpu);

      if (ft->clock_tick_ref)
            return ft->clock_tick_ref;
      return cpu_data(cpu).clock_tick;
}

#ifdef CONFIG_CPU_FREQ

static int sparc64_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
                            void *data)
{
      struct cpufreq_freqs *freq = data;
      unsigned int cpu = freq->cpu;
      struct freq_table *ft = &per_cpu(sparc64_freq_table, cpu);

      if (!ft->ref_freq) {
            ft->ref_freq = freq->old;
            ft->clock_tick_ref = cpu_data(cpu).clock_tick;
      }
      if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
          (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
          (val == CPUFREQ_RESUMECHANGE)) {
            cpu_data(cpu).clock_tick =
                  cpufreq_scale(ft->clock_tick_ref,
                              ft->ref_freq,
                              freq->new);
      }

      return 0;
}

static struct notifier_block sparc64_cpufreq_notifier_block = {
      .notifier_call    = sparc64_cpufreq_notifier
};

static int __init register_sparc64_cpufreq_notifier(void)
{

      cpufreq_register_notifier(&sparc64_cpufreq_notifier_block,
                          CPUFREQ_TRANSITION_NOTIFIER);
      return 0;
}

core_initcall(register_sparc64_cpufreq_notifier);

#endif /* CONFIG_CPU_FREQ */

static int sparc64_next_event(unsigned long delta,
                        struct clock_event_device *evt)
{
      return tick_ops->add_compare(delta) ? -ETIME : 0;
}

static void sparc64_timer_setup(enum clock_event_mode mode,
                        struct clock_event_device *evt)
{
      switch (mode) {
      case CLOCK_EVT_MODE_ONESHOT:
      case CLOCK_EVT_MODE_RESUME:
            break;

      case CLOCK_EVT_MODE_SHUTDOWN:
            tick_ops->disable_irq();
            break;

      case CLOCK_EVT_MODE_PERIODIC:
      case CLOCK_EVT_MODE_UNUSED:
            WARN_ON(1);
            break;
      };
}

static struct clock_event_device sparc64_clockevent = {
      .features   = CLOCK_EVT_FEAT_ONESHOT,
      .set_mode   = sparc64_timer_setup,
      .set_next_event   = sparc64_next_event,
      .rating           = 100,
      .shift            = 30,
      .irq        = -1,
};
static DEFINE_PER_CPU(struct clock_event_device, sparc64_events);

void timer_interrupt(int irq, struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);
      unsigned long tick_mask = tick_ops->softint_mask;
      int cpu = smp_processor_id();
      struct clock_event_device *evt = &per_cpu(sparc64_events, cpu);

      clear_softint(tick_mask);

      irq_enter();

      kstat_this_cpu.irqs[0]++;

      if (unlikely(!evt->event_handler)) {
            printk(KERN_WARNING
                   "Spurious SPARC64 timer interrupt on cpu %d\n", cpu);
      } else
            evt->event_handler(evt);

      irq_exit();

      set_irq_regs(old_regs);
}

void __devinit setup_sparc64_timer(void)
{
      struct clock_event_device *sevt;
      unsigned long pstate;

      /* Guarantee that the following sequences execute
       * uninterrupted.
       */
      __asm__ __volatile__("rdpr    %%pstate, %0\n\t"
                       "wrpr  %0, %1, %%pstate"
                       : "=r" (pstate)
                       : "i" (PSTATE_IE));

      tick_ops->init_tick();

      /* Restore PSTATE_IE. */
      __asm__ __volatile__("wrpr    %0, 0x0, %%pstate"
                       : /* no outputs */
                       : "r" (pstate));

      sevt = &__get_cpu_var(sparc64_events);

      memcpy(sevt, &sparc64_clockevent, sizeof(*sevt));
      sevt->cpumask = cpumask_of_cpu(smp_processor_id());

      clockevents_register_device(sevt);
}

#define SPARC64_NSEC_PER_CYC_SHIFT  10UL

static struct clocksource clocksource_tick = {
      .rating           = 100,
      .mask       = CLOCKSOURCE_MASK(64),
      .shift            = 16,
      .flags            = CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init setup_clockevent_multiplier(unsigned long hz)
{
      unsigned long mult, shift = 32;

      while (1) {
            mult = div_sc(hz, NSEC_PER_SEC, shift);
            if (mult && (mult >> 32UL) == 0UL)
                  break;

            shift--;
      }

      sparc64_clockevent.shift = shift;
      sparc64_clockevent.mult = mult;
}

static unsigned long tb_ticks_per_usec __read_mostly;

void __delay(unsigned long loops)
{
      unsigned long bclock, now;

      bclock = tick_ops->get_tick();
      do {
            now = tick_ops->get_tick();
      } while ((now-bclock) < loops);
}
EXPORT_SYMBOL(__delay);

void udelay(unsigned long usecs)
{
      __delay(tb_ticks_per_usec * usecs);
}
EXPORT_SYMBOL(udelay);

void __init time_init(void)
{
      unsigned long clock = sparc64_init_timers();

      tb_ticks_per_usec = clock / USEC_PER_SEC;

      timer_ticks_per_nsec_quotient =
            clocksource_hz2mult(clock, SPARC64_NSEC_PER_CYC_SHIFT);

      clocksource_tick.name = tick_ops->name;
      clocksource_tick.mult =
            clocksource_hz2mult(clock,
                            clocksource_tick.shift);
      clocksource_tick.read = tick_ops->get_tick;

      printk("clocksource: mult[%x] shift[%d]\n",
             clocksource_tick.mult, clocksource_tick.shift);

      clocksource_register(&clocksource_tick);

      sparc64_clockevent.name = tick_ops->name;

      setup_clockevent_multiplier(clock);

      sparc64_clockevent.max_delta_ns =
            clockevent_delta2ns(0x7fffffffffffffffUL, &sparc64_clockevent);
      sparc64_clockevent.min_delta_ns =
            clockevent_delta2ns(0xF, &sparc64_clockevent);

      printk("clockevent: mult[%lx] shift[%d]\n",
             sparc64_clockevent.mult, sparc64_clockevent.shift);

      setup_sparc64_timer();
}

unsigned long long sched_clock(void)
{
      unsigned long ticks = tick_ops->get_tick();

      return (ticks * timer_ticks_per_nsec_quotient)
            >> SPARC64_NSEC_PER_CYC_SHIFT;
}

static int set_rtc_mmss(unsigned long nowtime)
{
      int real_seconds, real_minutes, chip_minutes;
      void __iomem *mregs = mstk48t02_regs;
#ifdef CONFIG_PCI
      unsigned long dregs = ds1287_regs;
      void __iomem *bregs = bq4802_regs;
#else
      unsigned long dregs = 0UL;
      void __iomem *bregs = 0UL;
#endif
      unsigned long flags;
      u8 tmp;

      /* 
       * Not having a register set can lead to trouble.
       * Also starfire doesn't have a tod clock.
       */
      if (!mregs && !dregs && !bregs)
            return -1;

      if (mregs) {
            spin_lock_irqsave(&mostek_lock, flags);

            /* Read the current RTC minutes. */
            tmp = mostek_read(mregs + MOSTEK_CREG);
            tmp |= MSTK_CREG_READ;
            mostek_write(mregs + MOSTEK_CREG, tmp);

            chip_minutes = MSTK_REG_MIN(mregs);

            tmp = mostek_read(mregs + MOSTEK_CREG);
            tmp &= ~MSTK_CREG_READ;
            mostek_write(mregs + MOSTEK_CREG, tmp);

            /*
             * since we're only adjusting minutes and seconds,
             * don't interfere with hour overflow. This avoids
             * messing with unknown time zones but requires your
             * RTC not to be off by more than 15 minutes
             */
            real_seconds = nowtime % 60;
            real_minutes = nowtime / 60;
            if (((abs(real_minutes - chip_minutes) + 15)/30) & 1)
                  real_minutes += 30;     /* correct for half hour time zone */
            real_minutes %= 60;

            if (abs(real_minutes - chip_minutes) < 30) {
                  tmp = mostek_read(mregs + MOSTEK_CREG);
                  tmp |= MSTK_CREG_WRITE;
                  mostek_write(mregs + MOSTEK_CREG, tmp);

                  MSTK_SET_REG_SEC(mregs,real_seconds);
                  MSTK_SET_REG_MIN(mregs,real_minutes);

                  tmp = mostek_read(mregs + MOSTEK_CREG);
                  tmp &= ~MSTK_CREG_WRITE;
                  mostek_write(mregs + MOSTEK_CREG, tmp);

                  spin_unlock_irqrestore(&mostek_lock, flags);

                  return 0;
            } else {
                  spin_unlock_irqrestore(&mostek_lock, flags);

                  return -1;
            }
      } else if (bregs) {
            int retval = 0;
            unsigned char val = readb(bregs + 0x0e);

            /* BQ4802 RTC chip. */

            writeb(val | 0x08, bregs + 0x0e);

            chip_minutes = readb(bregs + 0x02);
            BCD_TO_BIN(chip_minutes);
            real_seconds = nowtime % 60;
            real_minutes = nowtime / 60;
            if (((abs(real_minutes - chip_minutes) + 15)/30) & 1)
                  real_minutes += 30;
            real_minutes %= 60;

            if (abs(real_minutes - chip_minutes) < 30) {
                  BIN_TO_BCD(real_seconds);
                  BIN_TO_BCD(real_minutes);
                  writeb(real_seconds, bregs + 0x00);
                  writeb(real_minutes, bregs + 0x02);
            } else {
                  printk(KERN_WARNING
                         "set_rtc_mmss: can't update from %d to %d\n",
                         chip_minutes, real_minutes);
                  retval = -1;
            }

            writeb(val, bregs + 0x0e);

            return retval;
      } else {
            int retval = 0;
            unsigned char save_control, save_freq_select;

            /* Stolen from arch/i386/kernel/time.c, see there for
             * credits and descriptive comments.
             */
            spin_lock_irqsave(&rtc_lock, flags);
            save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
            CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);

            save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
            CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);

            chip_minutes = CMOS_READ(RTC_MINUTES);
            if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
                  BCD_TO_BIN(chip_minutes);
            real_seconds = nowtime % 60;
            real_minutes = nowtime / 60;
            if (((abs(real_minutes - chip_minutes) + 15)/30) & 1)
                  real_minutes += 30;
            real_minutes %= 60;

            if (abs(real_minutes - chip_minutes) < 30) {
                  if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
                        BIN_TO_BCD(real_seconds);
                        BIN_TO_BCD(real_minutes);
                  }
                  CMOS_WRITE(real_seconds,RTC_SECONDS);
                  CMOS_WRITE(real_minutes,RTC_MINUTES);
            } else {
                  printk(KERN_WARNING
                         "set_rtc_mmss: can't update from %d to %d\n",
                         chip_minutes, real_minutes);
                  retval = -1;
            }

            CMOS_WRITE(save_control, RTC_CONTROL);
            CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
            spin_unlock_irqrestore(&rtc_lock, flags);

            return retval;
      }
}

#define RTC_IS_OPEN           0x01  /* means /dev/rtc is in use   */
static unsigned char mini_rtc_status;     /* bitmapped status byte.     */

#define FEBRUARY  2
#define     STARTOFTIME 1970
#define SECDAY          86400L
#define SECYR           (SECDAY * 365)
#define     leapyear(year)          ((year) % 4 == 0 && \
                         ((year) % 100 != 0 || (year) % 400 == 0))
#define     days_in_year(a)   (leapyear(a) ? 366 : 365)
#define     days_in_month(a)  (month_days[(a) - 1])

static int month_days[12] = {
      31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

/*
 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
 */
static void GregorianDay(struct rtc_time * tm)
{
      int leapsToDate;
      int lastYear;
      int day;
      int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

      lastYear = tm->tm_year - 1;

      /*
       * Number of leap corrections to apply up to end of last year
       */
      leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;

      /*
       * This year is a leap year if it is divisible by 4 except when it is
       * divisible by 100 unless it is divisible by 400
       *
       * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
       */
      day = tm->tm_mon > 2 && leapyear(tm->tm_year);

      day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
               tm->tm_mday;

      tm->tm_wday = day % 7;
}

static void to_tm(int tim, struct rtc_time *tm)
{
      register int    i;
      register long   hms, day;

      day = tim / SECDAY;
      hms = tim % SECDAY;

      /* Hours, minutes, seconds are easy */
      tm->tm_hour = hms / 3600;
      tm->tm_min = (hms % 3600) / 60;
      tm->tm_sec = (hms % 3600) % 60;

      /* Number of years in days */
      for (i = STARTOFTIME; day >= days_in_year(i); i++)
            day -= days_in_year(i);
      tm->tm_year = i;

      /* Number of months in days left */
      if (leapyear(tm->tm_year))
            days_in_month(FEBRUARY) = 29;
      for (i = 1; day >= days_in_month(i); i++)
            day -= days_in_month(i);
      days_in_month(FEBRUARY) = 28;
      tm->tm_mon = i;

      /* Days are what is left over (+1) from all that. */
      tm->tm_mday = day + 1;

      /*
       * Determine the day of week
       */
      GregorianDay(tm);
}

/* Both Starfire and SUN4V give us seconds since Jan 1st, 1970,
 * aka Unix time.  So we have to convert to/from rtc_time.
 */
static void starfire_get_rtc_time(struct rtc_time *time)
{
      u32 seconds = starfire_get_time();

      to_tm(seconds, time);
      time->tm_year -= 1900;
      time->tm_mon -= 1;
}

static int starfire_set_rtc_time(struct rtc_time *time)
{
      u32 seconds = mktime(time->tm_year + 1900, time->tm_mon + 1,
                       time->tm_mday, time->tm_hour,
                       time->tm_min, time->tm_sec);

      return starfire_set_time(seconds);
}

static void hypervisor_get_rtc_time(struct rtc_time *time)
{
      u32 seconds = hypervisor_get_time();

      to_tm(seconds, time);
      time->tm_year -= 1900;
      time->tm_mon -= 1;
}

static int hypervisor_set_rtc_time(struct rtc_time *time)
{
      u32 seconds = mktime(time->tm_year + 1900, time->tm_mon + 1,
                       time->tm_mday, time->tm_hour,
                       time->tm_min, time->tm_sec);

      return hypervisor_set_time(seconds);
}

#ifdef CONFIG_PCI
static void bq4802_get_rtc_time(struct rtc_time *time)
{
      unsigned char val = readb(bq4802_regs + 0x0e);
      unsigned int century;

      writeb(val | 0x08, bq4802_regs + 0x0e);

      time->tm_sec = readb(bq4802_regs + 0x00);
      time->tm_min = readb(bq4802_regs + 0x02);
      time->tm_hour = readb(bq4802_regs + 0x04);
      time->tm_mday = readb(bq4802_regs + 0x06);
      time->tm_mon = readb(bq4802_regs + 0x09);
      time->tm_year = readb(bq4802_regs + 0x0a);
      time->tm_wday = readb(bq4802_regs + 0x08);
      century = readb(bq4802_regs + 0x0f);

      writeb(val, bq4802_regs + 0x0e);

      BCD_TO_BIN(time->tm_sec);
      BCD_TO_BIN(time->tm_min);
      BCD_TO_BIN(time->tm_hour);
      BCD_TO_BIN(time->tm_mday);
      BCD_TO_BIN(time->tm_mon);
      BCD_TO_BIN(time->tm_year);
      BCD_TO_BIN(time->tm_wday);
      BCD_TO_BIN(century);

      time->tm_year += (century * 100);
      time->tm_year -= 1900;

      time->tm_mon--;
}

static int bq4802_set_rtc_time(struct rtc_time *time)
{
      unsigned char val = readb(bq4802_regs + 0x0e);
      unsigned char sec, min, hrs, day, mon, yrs, century;
      unsigned int year;

      year = time->tm_year + 1900;
      century = year / 100;
      yrs = year % 100;

      mon = time->tm_mon + 1;   /* tm_mon starts at zero */
      day = time->tm_mday;
      hrs = time->tm_hour;
      min = time->tm_min;
      sec = time->tm_sec;

      BIN_TO_BCD(sec);
      BIN_TO_BCD(min);
      BIN_TO_BCD(hrs);
      BIN_TO_BCD(day);
      BIN_TO_BCD(mon);
      BIN_TO_BCD(yrs);
      BIN_TO_BCD(century);

      writeb(val | 0x08, bq4802_regs + 0x0e);

      writeb(sec, bq4802_regs + 0x00);
      writeb(min, bq4802_regs + 0x02);
      writeb(hrs, bq4802_regs + 0x04);
      writeb(day, bq4802_regs + 0x06);
      writeb(mon, bq4802_regs + 0x09);
      writeb(yrs, bq4802_regs + 0x0a);
      writeb(century, bq4802_regs + 0x0f);

      writeb(val, bq4802_regs + 0x0e);

      return 0;
}

static void cmos_get_rtc_time(struct rtc_time *rtc_tm)
{
      unsigned char ctrl;

      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);
      rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);

      ctrl = CMOS_READ(RTC_CONTROL);
      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);
      }

      if (rtc_tm->tm_year <= 69)
            rtc_tm->tm_year += 100;

      rtc_tm->tm_mon--;
}

static int cmos_set_rtc_time(struct rtc_time *rtc_tm)
{
      unsigned char mon, day, hrs, min, sec;
      unsigned char save_control, save_freq_select;
      unsigned int yrs;

      yrs = rtc_tm->tm_year;
      mon = rtc_tm->tm_mon + 1;
      day = rtc_tm->tm_mday;
      hrs = rtc_tm->tm_hour;
      min = rtc_tm->tm_min;
      sec = rtc_tm->tm_sec;

      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);

      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);

      return 0;
}
#endif /* CONFIG_PCI */

static void mostek_get_rtc_time(struct rtc_time *rtc_tm)
{
      void __iomem *regs = mstk48t02_regs;
      u8 tmp;

      spin_lock_irq(&mostek_lock);

      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp |= MSTK_CREG_READ;
      mostek_write(regs + MOSTEK_CREG, tmp);

      rtc_tm->tm_sec = MSTK_REG_SEC(regs);
      rtc_tm->tm_min = MSTK_REG_MIN(regs);
      rtc_tm->tm_hour = MSTK_REG_HOUR(regs);
      rtc_tm->tm_mday = MSTK_REG_DOM(regs);
      rtc_tm->tm_mon = MSTK_REG_MONTH(regs);
      rtc_tm->tm_year = MSTK_CVT_YEAR( MSTK_REG_YEAR(regs) );
      rtc_tm->tm_wday = MSTK_REG_DOW(regs);

      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp &= ~MSTK_CREG_READ;
      mostek_write(regs + MOSTEK_CREG, tmp);

      spin_unlock_irq(&mostek_lock);

      rtc_tm->tm_mon--;
      rtc_tm->tm_wday--;
      rtc_tm->tm_year -= 1900;
}

static int mostek_set_rtc_time(struct rtc_time *rtc_tm)
{
      unsigned char mon, day, hrs, min, sec, wday;
      void __iomem *regs = mstk48t02_regs;
      unsigned int yrs;
      u8 tmp;

      yrs = rtc_tm->tm_year + 1900;
      mon = rtc_tm->tm_mon + 1;
      day = rtc_tm->tm_mday;
      wday = rtc_tm->tm_wday + 1;
      hrs = rtc_tm->tm_hour;
      min = rtc_tm->tm_min;
      sec = rtc_tm->tm_sec;

      spin_lock_irq(&mostek_lock);

      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp |= MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);

      MSTK_SET_REG_SEC(regs, sec);
      MSTK_SET_REG_MIN(regs, min);
      MSTK_SET_REG_HOUR(regs, hrs);
      MSTK_SET_REG_DOW(regs, wday);
      MSTK_SET_REG_DOM(regs, day);
      MSTK_SET_REG_MONTH(regs, mon);
      MSTK_SET_REG_YEAR(regs, yrs - MSTK_YEAR_ZERO);

      tmp = mostek_read(regs + MOSTEK_CREG);
      tmp &= ~MSTK_CREG_WRITE;
      mostek_write(regs + MOSTEK_CREG, tmp);

      spin_unlock_irq(&mostek_lock);

      return 0;
}

struct mini_rtc_ops {
      void (*get_rtc_time)(struct rtc_time *);
      int (*set_rtc_time)(struct rtc_time *);
};

static struct mini_rtc_ops starfire_rtc_ops = {
      .get_rtc_time = starfire_get_rtc_time,
      .set_rtc_time = starfire_set_rtc_time,
};

static struct mini_rtc_ops hypervisor_rtc_ops = {
      .get_rtc_time = hypervisor_get_rtc_time,
      .set_rtc_time = hypervisor_set_rtc_time,
};

#ifdef CONFIG_PCI
static struct mini_rtc_ops bq4802_rtc_ops = {
      .get_rtc_time = bq4802_get_rtc_time,
      .set_rtc_time = bq4802_set_rtc_time,
};

static struct mini_rtc_ops cmos_rtc_ops = {
      .get_rtc_time = cmos_get_rtc_time,
      .set_rtc_time = cmos_set_rtc_time,
};
#endif /* CONFIG_PCI */

static struct mini_rtc_ops mostek_rtc_ops = {
      .get_rtc_time = mostek_get_rtc_time,
      .set_rtc_time = mostek_set_rtc_time,
};

static struct mini_rtc_ops *mini_rtc_ops;

static inline void mini_get_rtc_time(struct rtc_time *time)
{
      unsigned long flags;

      spin_lock_irqsave(&rtc_lock, flags);
      mini_rtc_ops->get_rtc_time(time);
      spin_unlock_irqrestore(&rtc_lock, flags);
}

static inline int mini_set_rtc_time(struct rtc_time *time)
{
      unsigned long flags;
      int err;

      spin_lock_irqsave(&rtc_lock, flags);
      err = mini_rtc_ops->set_rtc_time(time);
      spin_unlock_irqrestore(&rtc_lock, flags);

      return err;
}

static int mini_rtc_ioctl(struct inode *inode, struct file *file,
                    unsigned int cmd, unsigned long arg)
{
      struct rtc_time wtime;
      void __user *argp = (void __user *)arg;

      switch (cmd) {

      case RTC_PLL_GET:
            return -EINVAL;

      case RTC_PLL_SET:
            return -EINVAL;

      case RTC_UIE_OFF: /* disable ints from RTC updates.   */
            return 0;

      case RTC_UIE_ON:  /* enable ints for RTC updates.     */
              return -EINVAL;

      case RTC_RD_TIME: /* Read the time/date from RTC      */
            /* this doesn't get week-day, who cares */
            memset(&wtime, 0, sizeof(wtime));
            mini_get_rtc_time(&wtime);

            return copy_to_user(argp, &wtime, sizeof(wtime)) ? -EFAULT : 0;

      case RTC_SET_TIME:      /* Set the RTC */
          {
            int year, days;

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

            if (copy_from_user(&wtime, argp, sizeof(wtime)))
                  return -EFAULT;

            year = wtime.tm_year + 1900;
            days = month_days[wtime.tm_mon] +
                   ((wtime.tm_mon == 1) && leapyear(year));

            if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) ||
                (wtime.tm_mday < 1))
                  return -EINVAL;

            if (wtime.tm_mday < 0 || wtime.tm_mday > days)
                  return -EINVAL;

            if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
                wtime.tm_min < 0 || wtime.tm_min >= 60 ||
                wtime.tm_sec < 0 || wtime.tm_sec >= 60)
                  return -EINVAL;

            return mini_set_rtc_time(&wtime);
          }
      }

      return -EINVAL;
}

static int mini_rtc_open(struct inode *inode, struct file *file)
{
      lock_kernel();
      if (mini_rtc_status & RTC_IS_OPEN) {
            unlock_kernel();
            return -EBUSY;
      }

      mini_rtc_status |= RTC_IS_OPEN;
      unlock_kernel();

      return 0;
}

static int mini_rtc_release(struct inode *inode, struct file *file)
{
      mini_rtc_status &= ~RTC_IS_OPEN;
      return 0;
}


static const struct file_operations mini_rtc_fops = {
      .owner            = THIS_MODULE,
      .ioctl            = mini_rtc_ioctl,
      .open       = mini_rtc_open,
      .release    = mini_rtc_release,
};

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

static int __init rtc_mini_init(void)
{
      int retval;

      if (tlb_type == hypervisor)
            mini_rtc_ops = &hypervisor_rtc_ops;
      else if (this_is_starfire)
            mini_rtc_ops = &starfire_rtc_ops;
#ifdef CONFIG_PCI
      else if (bq4802_regs)
            mini_rtc_ops = &bq4802_rtc_ops;
      else if (ds1287_regs)
            mini_rtc_ops = &cmos_rtc_ops;
#endif /* CONFIG_PCI */
      else if (mstk48t02_regs)
            mini_rtc_ops = &mostek_rtc_ops;
      else
            return -ENODEV;

      printk(KERN_INFO "Mini RTC Driver\n");

      retval = misc_register(&rtc_mini_dev);
      if (retval < 0)
            return retval;

      return 0;
}

static void __exit rtc_mini_exit(void)
{
      misc_deregister(&rtc_mini_dev);
}

int __devinit read_current_timer(unsigned long *timer_val)
{
      *timer_val = tick_ops->get_tick();
      return 0;
}

module_init(rtc_mini_init);
module_exit(rtc_mini_exit);

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