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![Arnd Bergmann](/assets/img/avatar_default.png)
The x86 platform operations are fairly isolated, so it's easy to change them from using timespec to timespec64. It has been checked that all the users and callers are safe, and there is only one critical function that is broken beyond 2106: pvclock_read_wallclock() uses a 32-bit number of seconds since the epoch to communicate the boot time between host and guest in a virtual environment. This will work until 2106, but fixing this is outside the scope of this change, Add a comment at least. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Acked-by: Radim Krčmář <rkrcmar@redhat.com> Acked-by: Jan Kiszka <jan.kiszka@siemens.com> Cc: Juergen Gross <jgross@suse.com> Cc: jailhouse-dev@googlegroups.com Cc: Borislav Petkov <bp@suse.de> Cc: kvm@vger.kernel.org Cc: y2038@lists.linaro.org Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: xen-devel@lists.xenproject.org Cc: John Stultz <john.stultz@linaro.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Joao Martins <joao.m.martins@oracle.com> Link: https://lkml.kernel.org/r/20180427201435.3194219-1-arnd@arndb.de
207 lines
4.8 KiB
C
207 lines
4.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* RTC related functions
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*/
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#include <linux/platform_device.h>
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#include <linux/mc146818rtc.h>
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#include <linux/acpi.h>
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#include <linux/bcd.h>
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#include <linux/export.h>
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#include <linux/pnp.h>
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#include <linux/of.h>
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#include <asm/vsyscall.h>
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#include <asm/x86_init.h>
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#include <asm/time.h>
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#include <asm/intel-mid.h>
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#include <asm/setup.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;
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EXPORT_SYMBOL(cmos_lock);
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#endif /* CONFIG_X86_32 */
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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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int mach_set_rtc_mmss(const struct timespec64 *now)
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{
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unsigned long long nowtime = now->tv_sec;
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struct rtc_time tm;
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int retval = 0;
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rtc_time64_to_tm(nowtime, &tm);
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if (!rtc_valid_tm(&tm)) {
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retval = mc146818_set_time(&tm);
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if (retval)
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printk(KERN_ERR "%s: RTC write failed with error %d\n",
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__func__, retval);
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} else {
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printk(KERN_ERR
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"%s: Invalid RTC value: write of %llx to RTC failed\n",
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__func__, nowtime);
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retval = -EINVAL;
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}
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return retval;
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}
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void mach_get_cmos_time(struct timespec64 *now)
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{
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unsigned int status, year, mon, day, hour, min, sec, century = 0;
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unsigned long flags;
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/*
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* If pm_trace abused the RTC as storage, set the timespec to 0,
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* which tells the caller that this RTC value is unusable.
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*/
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if (!pm_trace_rtc_valid()) {
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now->tv_sec = now->tv_nsec = 0;
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return;
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}
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spin_lock_irqsave(&rtc_lock, flags);
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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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spin_unlock_irqrestore(&rtc_lock, flags);
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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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} else
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year += CMOS_YEARS_OFFS;
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now->tv_sec = mktime64(year, mon, day, hour, min, sec);
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now->tv_nsec = 0;
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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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int update_persistent_clock64(struct timespec64 now)
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{
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return x86_platform.set_wallclock(&now);
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}
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/* not static: needed by APM */
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void read_persistent_clock64(struct timespec64 *ts)
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{
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x86_platform.get_wallclock(ts);
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}
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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 * const 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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if (!x86_platform.legacy.rtc)
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return -ENODEV;
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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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