arch/x86/kernel/rtc.c - linux - Git at Google

 /*
  * RTC related functions
  */
 #include <linux/platform_device.h>
 #include <linux/mc146818rtc.h>
 #include <linux/acpi.h>
 #include <linux/bcd.h>
 #include <linux/pnp.h>
 #include <linux/of.h>

 #include <asm/vsyscall.h>
 #include <asm/x86_init.h>
 #include <asm/time.h>

 #ifdef CONFIG_X86_32
 /*
  * This is a special lock that is owned by the CPU and holds the index
  * register we are working with.  It is required for NMI access to the
  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  */
 volatile unsigned long cmos_lock;
 EXPORT_SYMBOL(cmos_lock);
 #endif /* CONFIG_X86_32 */

 /* For two digit years assume time is always after that */
 #define CMOS_YEARS_OFFS 2000

 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);

 /*
  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
  * called 500 ms after the second nowtime has started, because when
  * nowtime is written into the registers of the CMOS clock, it will
  * jump to the next second precisely 500 ms later. Check the Motorola
  * MC146818A or Dallas DS12887 data sheet for details.
  *
  * BUG: This routine does not handle hour overflow properly; it just
  *      sets the minutes. Usually you'll only notice that after reboot!
  */
 int mach_set_rtc_mmss(unsigned long nowtime)
 {
 	int real_seconds, real_minutes, cmos_minutes;
 	unsigned char save_control, save_freq_select;
 	unsigned long flags;
 	int retval = 0;

 	spin_lock_irqsave(&rtc_lock, flags);

 	 /* tell the clock it's being set */
 	save_control = CMOS_READ(RTC_CONTROL);
 	CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);

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

 	cmos_minutes = CMOS_READ(RTC_MINUTES);
 	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
 		cmos_minutes = bcd2bin(cmos_minutes);

 	/*
 	 * 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;
 	/* correct for half hour time zone */
 	if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
 		real_minutes += 30;
 	real_minutes %= 60;

 	if (abs(real_minutes - cmos_minutes) < 30) {
 		if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 			real_seconds = bin2bcd(real_seconds);
 			real_minutes = bin2bcd(real_minutes);
 		}
 		CMOS_WRITE(real_seconds, RTC_SECONDS);
 		CMOS_WRITE(real_minutes, RTC_MINUTES);
 	} else {
 		printk_once(KERN_NOTICE
 		       "set_rtc_mmss: can't update from %d to %d\n",
 		       cmos_minutes, real_minutes);
 		retval = -1;
 	}

 	/* The following flags have to be released exactly in this order,
 	 * otherwise the DS12887 (popular MC146818A clone with integrated
 	 * battery and quartz) will not reset the oscillator and will not
 	 * update precisely 500 ms later. You won't find this mentioned in
 	 * the Dallas Semiconductor data sheets, but who believes data
 	 * sheets anyway ...                           -- Markus Kuhn
 	 */
 	CMOS_WRITE(save_control, RTC_CONTROL);
 	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

 	spin_unlock_irqrestore(&rtc_lock, flags);

 	return retval;
 }

 unsigned long mach_get_cmos_time(void)
 {
 	unsigned int status, year, mon, day, hour, min, sec, century = 0;
 	unsigned long flags;

 	spin_lock_irqsave(&rtc_lock, flags);

 	/*
 	 * If UIP is clear, then we have >= 244 microseconds before
 	 * RTC registers will be updated.  Spec sheet says that this
 	 * is the reliable way to read RTC - registers. If UIP is set
 	 * then the register access might be invalid.
 	 */
 	while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
 		cpu_relax();

 	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);

 #ifdef CONFIG_ACPI
 	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
 	    acpi_gbl_FADT.century)
 		century = CMOS_READ(acpi_gbl_FADT.century);
 #endif

 	status = CMOS_READ(RTC_CONTROL);
 	WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));

 	spin_unlock_irqrestore(&rtc_lock, flags);

 	if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
 		sec = bcd2bin(sec);
 		min = bcd2bin(min);
 		hour = bcd2bin(hour);
 		day = bcd2bin(day);
 		mon = bcd2bin(mon);
 		year = bcd2bin(year);
 	}

 	if (century) {
 		century = bcd2bin(century);
 		year += century * 100;
 		printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
 	} else
 		year += CMOS_YEARS_OFFS;

 	return mktime(year, mon, day, hour, min, sec);
 }

 /* Routines for accessing the CMOS RAM/RTC. */
 unsigned char rtc_cmos_read(unsigned char addr)
 {
 	unsigned char val;

 	lock_cmos_prefix(addr);
 	outb(addr, RTC_PORT(0));
 	val = inb(RTC_PORT(1));
 	lock_cmos_suffix(addr);

 	return val;
 }
 EXPORT_SYMBOL(rtc_cmos_read);

 void rtc_cmos_write(unsigned char val, unsigned char addr)
 {
 	lock_cmos_prefix(addr);
 	outb(addr, RTC_PORT(0));
 	outb(val, RTC_PORT(1));
 	lock_cmos_suffix(addr);
 }
 EXPORT_SYMBOL(rtc_cmos_write);

 int update_persistent_clock(struct timespec now)
 {
 	return x86_platform.set_wallclock(now.tv_sec);
 }

 /* not static: needed by APM */
 void read_persistent_clock(struct timespec *ts)
 {
 	unsigned long retval;

 	retval = x86_platform.get_wallclock();

 	ts->tv_sec = retval;
 	ts->tv_nsec = 0;
 }

 unsigned long long native_read_tsc(void)
 {
 	return __native_read_tsc();
 }
 EXPORT_SYMBOL(native_read_tsc);


 static struct resource rtc_resources[] = {
 	[0] = {
 		.start	= RTC_PORT(0),
 		.end	= RTC_PORT(1),
 		.flags	= IORESOURCE_IO,
 	},
 	[1] = {
 		.start	= RTC_IRQ,
 		.end	= RTC_IRQ,
 		.flags	= IORESOURCE_IRQ,
 	}
 };

 static struct platform_device rtc_device = {
 	.name		= "rtc_cmos",
 	.id		= -1,
 	.resource	= rtc_resources,
 	.num_resources	= ARRAY_SIZE(rtc_resources),
 };

 static __init int add_rtc_cmos(void)
 {
 #ifdef CONFIG_PNP
 	static const char *ids[] __initconst =
 	    { "PNP0b00", "PNP0b01", "PNP0b02", };
 	struct pnp_dev *dev;
 	struct pnp_id *id;
 	int i;

 	pnp_for_each_dev(dev) {
 		for (id = dev->id; id; id = id->next) {
 			for (i = 0; i < ARRAY_SIZE(ids); i++) {
 				if (compare_pnp_id(id, ids[i]) != 0)
 					return 0;
 			}
 		}
 	}
 #endif
 	if (of_have_populated_dt())
 		return 0;

 	platform_device_register(&rtc_device);
 	dev_info(&rtc_device.dev,
 		 "registered platform RTC device (no PNP device found)\n");

 	return 0;
 }
 device_initcall(add_rtc_cmos);
	/*
	* RTC related functions
	*/
	#include <linux/platform_device.h>
	#include <linux/mc146818rtc.h>
	#include <linux/acpi.h>
	#include <linux/bcd.h>
	#include <linux/pnp.h>
	#include <linux/of.h>

	#include <asm/vsyscall.h>
	#include <asm/x86_init.h>
	#include <asm/time.h>

	#ifdef CONFIG_X86_32
	/*
	* This is a special lock that is owned by the CPU and holds the index
	* register we are working with. It is required for NMI access to the
	* CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
	*/
	volatile unsigned long cmos_lock;
	EXPORT_SYMBOL(cmos_lock);
	#endif /* CONFIG_X86_32 */

	/* For two digit years assume time is always after that */
	#define CMOS_YEARS_OFFS 2000

	DEFINE_SPINLOCK(rtc_lock);
	EXPORT_SYMBOL(rtc_lock);

	/*
	* In order to set the CMOS clock precisely, set_rtc_mmss has to be
	* called 500 ms after the second nowtime has started, because when
	* nowtime is written into the registers of the CMOS clock, it will
	* jump to the next second precisely 500 ms later. Check the Motorola
	* MC146818A or Dallas DS12887 data sheet for details.
	*
	* BUG: This routine does not handle hour overflow properly; it just
	* sets the minutes. Usually you'll only notice that after reboot!
	*/
	int mach_set_rtc_mmss(unsigned long nowtime)
	{
	int real_seconds, real_minutes, cmos_minutes;
	unsigned char save_control, save_freq_select;
	unsigned long flags;
	int retval = 0;

	spin_lock_irqsave(&rtc_lock, flags);

	/* tell the clock it's being set */
	save_control = CMOS_READ(RTC_CONTROL);
	CMOS_WRITE((save_control\|RTC_SET), RTC_CONTROL);

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

	cmos_minutes = CMOS_READ(RTC_MINUTES);
	if (!(save_control & RTC_DM_BINARY) \|\| RTC_ALWAYS_BCD)
	cmos_minutes = bcd2bin(cmos_minutes);

	/*
	* 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;
	/* correct for half hour time zone */
	if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
	real_minutes += 30;
	real_minutes %= 60;

	if (abs(real_minutes - cmos_minutes) < 30) {
	if (!(save_control & RTC_DM_BINARY) \|\| RTC_ALWAYS_BCD) {
	real_seconds = bin2bcd(real_seconds);
	real_minutes = bin2bcd(real_minutes);
	}
	CMOS_WRITE(real_seconds, RTC_SECONDS);
	CMOS_WRITE(real_minutes, RTC_MINUTES);
	} else {
	printk_once(KERN_NOTICE
	"set_rtc_mmss: can't update from %d to %d\n",
	cmos_minutes, real_minutes);
	retval = -1;
	}

	/* The following flags have to be released exactly in this order,
	* otherwise the DS12887 (popular MC146818A clone with integrated
	* battery and quartz) will not reset the oscillator and will not
	* update precisely 500 ms later. You won't find this mentioned in
	* the Dallas Semiconductor data sheets, but who believes data
	* sheets anyway ... -- Markus Kuhn
	*/
	CMOS_WRITE(save_control, RTC_CONTROL);
	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

	spin_unlock_irqrestore(&rtc_lock, flags);

	return retval;
	}

	unsigned long mach_get_cmos_time(void)
	{
	unsigned int status, year, mon, day, hour, min, sec, century = 0;
	unsigned long flags;

	spin_lock_irqsave(&rtc_lock, flags);

	/*
	* If UIP is clear, then we have >= 244 microseconds before
	* RTC registers will be updated. Spec sheet says that this
	* is the reliable way to read RTC - registers. If UIP is set
	* then the register access might be invalid.
	*/
	while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
	cpu_relax();

	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);

	#ifdef CONFIG_ACPI
	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	acpi_gbl_FADT.century)
	century = CMOS_READ(acpi_gbl_FADT.century);
	#endif

	status = CMOS_READ(RTC_CONTROL);
	WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));

	spin_unlock_irqrestore(&rtc_lock, flags);

	if (RTC_ALWAYS_BCD \|\| !(status & RTC_DM_BINARY)) {
	sec = bcd2bin(sec);
	min = bcd2bin(min);
	hour = bcd2bin(hour);
	day = bcd2bin(day);
	mon = bcd2bin(mon);
	year = bcd2bin(year);
	}

	if (century) {
	century = bcd2bin(century);
	year += century * 100;
	printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
	} else
	year += CMOS_YEARS_OFFS;

	return mktime(year, mon, day, hour, min, sec);
	}

	/* Routines for accessing the CMOS RAM/RTC. */
	unsigned char rtc_cmos_read(unsigned char addr)
	{
	unsigned char val;

	lock_cmos_prefix(addr);
	outb(addr, RTC_PORT(0));
	val = inb(RTC_PORT(1));
	lock_cmos_suffix(addr);

	return val;
	}
	EXPORT_SYMBOL(rtc_cmos_read);

	void rtc_cmos_write(unsigned char val, unsigned char addr)
	{
	lock_cmos_prefix(addr);
	outb(addr, RTC_PORT(0));
	outb(val, RTC_PORT(1));
	lock_cmos_suffix(addr);
	}
	EXPORT_SYMBOL(rtc_cmos_write);

	int update_persistent_clock(struct timespec now)
	{
	return x86_platform.set_wallclock(now.tv_sec);
	}

	/* not static: needed by APM */
	void read_persistent_clock(struct timespec *ts)
	{
	unsigned long retval;

	retval = x86_platform.get_wallclock();

	ts->tv_sec = retval;
	ts->tv_nsec = 0;
	}

	unsigned long long native_read_tsc(void)
	{
	return __native_read_tsc();
	}
	EXPORT_SYMBOL(native_read_tsc);


	static struct resource rtc_resources[] = {
	[0] = {
	.start = RTC_PORT(0),
	.end = RTC_PORT(1),
	.flags = IORESOURCE_IO,
	},
	[1] = {
	.start = RTC_IRQ,
	.end = RTC_IRQ,
	.flags = IORESOURCE_IRQ,
	}
	};

	static struct platform_device rtc_device = {
	.name = "rtc_cmos",
	.id = -1,
	.resource = rtc_resources,
	.num_resources = ARRAY_SIZE(rtc_resources),
	};

	static __init int add_rtc_cmos(void)
	{
	#ifdef CONFIG_PNP
	static const char *ids[] __initconst =
	{ "PNP0b00", "PNP0b01", "PNP0b02", };
	struct pnp_dev *dev;
	struct pnp_id *id;
	int i;

	pnp_for_each_dev(dev) {
	for (id = dev->id; id; id = id->next) {
	for (i = 0; i < ARRAY_SIZE(ids); i++) {
	if (compare_pnp_id(id, ids[i]) != 0)
	return 0;
	}
	}
	}
	#endif
	if (of_have_populated_dt())
	return 0;

	platform_device_register(&rtc_device);
	dev_info(&rtc_device.dev,
	"registered platform RTC device (no PNP device found)\n");

	return 0;
	}
	device_initcall(add_rtc_cmos);