248 lines
6.2 KiB
C
248 lines
6.2 KiB
C
/*
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* RTC related functions
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*/
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#include <linux/acpi.h>
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#include <linux/bcd.h>
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#include <linux/mc146818rtc.h>
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#include <linux/platform_device.h>
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#include <linux/pnp.h>
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#include <asm/time.h>
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#include <asm/vsyscall.h>
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#ifdef CONFIG_X86_32
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/*
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* This is a special lock that is owned by the CPU and holds the index
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* register we are working with. It is required for NMI access to the
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* CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
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*/
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volatile unsigned long cmos_lock = 0;
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EXPORT_SYMBOL(cmos_lock);
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#endif
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/* For two digit years assume time is always after that */
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#define CMOS_YEARS_OFFS 2000
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DEFINE_SPINLOCK(rtc_lock);
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EXPORT_SYMBOL(rtc_lock);
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/*
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* In order to set the CMOS clock precisely, set_rtc_mmss has to be
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* called 500 ms after the second nowtime has started, because when
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* nowtime is written into the registers of the CMOS clock, it will
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* jump to the next second precisely 500 ms later. Check the Motorola
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* MC146818A or Dallas DS12887 data sheet for details.
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*
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* BUG: This routine does not handle hour overflow properly; it just
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* sets the minutes. Usually you'll only notice that after reboot!
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*/
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int mach_set_rtc_mmss(unsigned long nowtime)
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{
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int retval = 0;
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int real_seconds, real_minutes, cmos_minutes;
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unsigned char save_control, save_freq_select;
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/* tell the clock it's being set */
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save_control = CMOS_READ(RTC_CONTROL);
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CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
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/* stop and reset prescaler */
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save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
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CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
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cmos_minutes = CMOS_READ(RTC_MINUTES);
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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cmos_minutes = bcd2bin(cmos_minutes);
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/*
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* since we're only adjusting minutes and seconds,
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* don't interfere with hour overflow. This avoids
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* messing with unknown time zones but requires your
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* RTC not to be off by more than 15 minutes
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*/
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real_seconds = nowtime % 60;
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real_minutes = nowtime / 60;
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/* correct for half hour time zone */
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if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
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real_minutes += 30;
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real_minutes %= 60;
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if (abs(real_minutes - cmos_minutes) < 30) {
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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real_seconds = bin2bcd(real_seconds);
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real_minutes = bin2bcd(real_minutes);
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}
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CMOS_WRITE(real_seconds,RTC_SECONDS);
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CMOS_WRITE(real_minutes,RTC_MINUTES);
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} else {
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printk(KERN_WARNING
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"set_rtc_mmss: can't update from %d to %d\n",
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cmos_minutes, real_minutes);
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retval = -1;
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}
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/* The following flags have to be released exactly in this order,
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* otherwise the DS12887 (popular MC146818A clone with integrated
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* battery and quartz) will not reset the oscillator and will not
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* update precisely 500 ms later. You won't find this mentioned in
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* the Dallas Semiconductor data sheets, but who believes data
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* sheets anyway ... -- Markus Kuhn
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*/
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CMOS_WRITE(save_control, RTC_CONTROL);
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CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
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return retval;
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}
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unsigned long mach_get_cmos_time(void)
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{
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unsigned int status, year, mon, day, hour, min, sec, century = 0;
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/*
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* If UIP is clear, then we have >= 244 microseconds before
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* RTC registers will be updated. Spec sheet says that this
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* is the reliable way to read RTC - registers. If UIP is set
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* then the register access might be invalid.
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*/
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while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
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cpu_relax();
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sec = CMOS_READ(RTC_SECONDS);
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min = CMOS_READ(RTC_MINUTES);
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hour = CMOS_READ(RTC_HOURS);
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day = CMOS_READ(RTC_DAY_OF_MONTH);
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mon = CMOS_READ(RTC_MONTH);
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year = CMOS_READ(RTC_YEAR);
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#ifdef CONFIG_ACPI
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if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
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acpi_gbl_FADT.century)
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century = CMOS_READ(acpi_gbl_FADT.century);
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#endif
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status = CMOS_READ(RTC_CONTROL);
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WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
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if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
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sec = bcd2bin(sec);
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min = bcd2bin(min);
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hour = bcd2bin(hour);
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day = bcd2bin(day);
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mon = bcd2bin(mon);
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year = bcd2bin(year);
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}
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if (century) {
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century = bcd2bin(century);
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year += century * 100;
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printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
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} else
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year += CMOS_YEARS_OFFS;
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return mktime(year, mon, day, hour, min, sec);
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}
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/* Routines for accessing the CMOS RAM/RTC. */
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unsigned char rtc_cmos_read(unsigned char addr)
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{
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unsigned char val;
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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val = inb(RTC_PORT(1));
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lock_cmos_suffix(addr);
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return val;
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}
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EXPORT_SYMBOL(rtc_cmos_read);
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void rtc_cmos_write(unsigned char val, unsigned char addr)
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{
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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outb(val, RTC_PORT(1));
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lock_cmos_suffix(addr);
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}
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EXPORT_SYMBOL(rtc_cmos_write);
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static int set_rtc_mmss(unsigned long nowtime)
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{
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int retval;
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unsigned long flags;
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spin_lock_irqsave(&rtc_lock, flags);
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retval = set_wallclock(nowtime);
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spin_unlock_irqrestore(&rtc_lock, flags);
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return retval;
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}
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/* not static: needed by APM */
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unsigned long read_persistent_clock(void)
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{
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unsigned long retval, flags;
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spin_lock_irqsave(&rtc_lock, flags);
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retval = get_wallclock();
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spin_unlock_irqrestore(&rtc_lock, flags);
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return retval;
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}
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int update_persistent_clock(struct timespec now)
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{
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return set_rtc_mmss(now.tv_sec);
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}
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unsigned long long native_read_tsc(void)
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{
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return __native_read_tsc();
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}
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EXPORT_SYMBOL(native_read_tsc);
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static struct resource rtc_resources[] = {
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[0] = {
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.start = RTC_PORT(0),
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.end = RTC_PORT(1),
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.flags = IORESOURCE_IO,
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},
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[1] = {
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.start = RTC_IRQ,
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.end = RTC_IRQ,
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.flags = IORESOURCE_IRQ,
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}
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};
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static struct platform_device rtc_device = {
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.name = "rtc_cmos",
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.id = -1,
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.resource = rtc_resources,
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.num_resources = ARRAY_SIZE(rtc_resources),
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};
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static __init int add_rtc_cmos(void)
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{
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#ifdef CONFIG_PNP
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static const char *ids[] __initconst =
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{ "PNP0b00", "PNP0b01", "PNP0b02", };
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struct pnp_dev *dev;
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struct pnp_id *id;
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int i;
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pnp_for_each_dev(dev) {
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for (id = dev->id; id; id = id->next) {
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for (i = 0; i < ARRAY_SIZE(ids); i++) {
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if (compare_pnp_id(id, ids[i]) != 0)
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return 0;
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}
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}
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}
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#endif
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platform_device_register(&rtc_device);
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dev_info(&rtc_device.dev,
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"registered platform RTC device (no PNP device found)\n");
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return 0;
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}
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device_initcall(add_rtc_cmos);
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