v4.19.13 snapshot.
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
new file mode 100644
index 0000000..586f718
--- /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);