diff options
Diffstat (limited to 'arch/x86/kernel/rtc.c')
| -rw-r--r-- | arch/x86/kernel/rtc.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c new file mode 100644 index 000000000..586f718b8 --- /dev/null +++ b/arch/x86/kernel/rtc.c @@ -0,0 +1,207 @@ +// 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); |