// SPDX-License-Identifier: GPL-2.0/* * RTC related functions */#include <linux/acpi.h>#include <linux/platform_device.h>#include <linux/mc146818rtc.h>#include <linux/export.h> #include <asm/vsyscall.h>#include <asm/x86_init.h>#include <asm/time.h>#include <asm/setup.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 arch/x86/include/asm/mc146818rtc.h for details. */volatile unsigned long cmos_lock;EXPORT_SYMBOL(cmos_lock);#endif /* CONFIG_X86_32 */ DEFINE_SPINLOCK(rtc_lock);EXPORT_SYMBOL(rtc_lock); /* * In order to set the CMOS clock precisely, mach_set_cmos_time 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. */int mach_set_cmos_time(const struct timespec64 *now){	unsigned long long nowtime = now->tv_sec;	struct rtc_time tm;	int retval = 0; 	rtc_time64_to_tm(nowtime, &tm);	if (!rtc_valid_tm(&tm)) {		retval = mc146818_set_time(&tm);		if (retval)			printk(KERN_ERR "%s: RTC write failed with error %d\n",			       __func__, retval);	} else {		printk(KERN_ERR		       "%s: Invalid RTC value: write of %llx to RTC failed\n",			__func__, nowtime);		retval = -EINVAL;	}	return retval;} void mach_get_cmos_time(struct timespec64 *now){	struct rtc_time tm; 	/*	 * If pm_trace abused the RTC as storage, set the timespec to 0,	 * which tells the caller that this RTC value is unusable.	 */	if (!pm_trace_rtc_valid()) {		now->tv_sec = now->tv_nsec = 0;		return;	} 	if (mc146818_get_time(&tm, 1000)) {		pr_err("Unable to read current time from RTC\n");		now->tv_sec = now->tv_nsec = 0;		return;	} 	now->tv_sec = rtc_tm_to_time64(&tm);	now->tv_nsec = 0;} /* 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_clock64(struct timespec64 now){	return x86_platform.set_wallclock(&now);} /* not static: needed by APM */void read_persistent_clock64(struct timespec64 *ts){	x86_platform.get_wallclock(ts);}  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){	if (cmos_rtc_platform_device_present)		return 0; 	if (!x86_platform.legacy.rtc)		return -ENODEV; 	platform_device_register(&rtc_device);	dev_info(&rtc_device.dev, "registered fallback platform RTC device\n"); 	return 0;}device_initcall(add_rtc_cmos);