// SPDX-License-Identifier: GPL-2.0 /* * RTC related functions */ #include <linux/platform_device.h> #include <linux/mc146818rtc.h> #include <linux/acpi.h> #include <linux/bcd.h> #include <linux/export.h> #include <linux/pnp.h> #include <linux/of.h> #include <asm/vsyscall.h> #include <asm/x86_init.h> #include <asm/time.h> #include <asm/intel-mid.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 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. */ int mach_set_rtc_mmss(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) { unsigned int status, year, mon, day, hour, min, sec, century = 0; unsigned long flags; /* * 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; } 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; } else year += CMOS_YEARS_OFFS; now->tv_sec = mktime64(year, mon, day, hour, min, sec); 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) { #ifdef CONFIG_PNP static const char * const 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 (!x86_platform.legacy.rtc) return -ENODEV; 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);