2 * RTC related functions
4 #include <linux/platform_device.h>
5 #include <linux/mc146818rtc.h>
6 #include <linux/acpi.h>
8 #include <linux/export.h>
12 #include <asm/vsyscall.h>
13 #include <asm/x86_init.h>
20 * This is a special lock that is owned by the CPU and holds the index
21 * register we are working with. It is required for NMI access to the
22 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
24 volatile unsigned long cmos_lock;
25 EXPORT_SYMBOL(cmos_lock);
26 #endif /* CONFIG_X86_32 */
28 /* For two digit years assume time is always after that */
29 #define CMOS_YEARS_OFFS 2000
31 DEFINE_SPINLOCK(rtc_lock);
32 EXPORT_SYMBOL(rtc_lock);
35 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
36 * called 500 ms after the second nowtime has started, because when
37 * nowtime is written into the registers of the CMOS clock, it will
38 * jump to the next second precisely 500 ms later. Check the Motorola
39 * MC146818A or Dallas DS12887 data sheet for details.
41 int mach_set_rtc_mmss(unsigned long nowtime)
46 rtc_time_to_tm(nowtime, &tm);
47 if (!rtc_valid_tm(&tm)) {
48 retval = set_rtc_time(&tm);
50 printk(KERN_ERR "%s: RTC write failed with error %d\n",
51 __FUNCTION__, retval);
54 "%s: Invalid RTC value: write of %lx to RTC failed\n",
55 __FUNCTION__, nowtime);
61 unsigned long mach_get_cmos_time(void)
63 unsigned int status, year, mon, day, hour, min, sec, century = 0;
66 spin_lock_irqsave(&rtc_lock, flags);
69 * If UIP is clear, then we have >= 244 microseconds before
70 * RTC registers will be updated. Spec sheet says that this
71 * is the reliable way to read RTC - registers. If UIP is set
72 * then the register access might be invalid.
74 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
77 sec = CMOS_READ(RTC_SECONDS);
78 min = CMOS_READ(RTC_MINUTES);
79 hour = CMOS_READ(RTC_HOURS);
80 day = CMOS_READ(RTC_DAY_OF_MONTH);
81 mon = CMOS_READ(RTC_MONTH);
82 year = CMOS_READ(RTC_YEAR);
85 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
86 acpi_gbl_FADT.century)
87 century = CMOS_READ(acpi_gbl_FADT.century);
90 status = CMOS_READ(RTC_CONTROL);
91 WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
93 spin_unlock_irqrestore(&rtc_lock, flags);
95 if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
101 year = bcd2bin(year);
105 century = bcd2bin(century);
106 year += century * 100;
108 year += CMOS_YEARS_OFFS;
110 return mktime(year, mon, day, hour, min, sec);
113 /* Routines for accessing the CMOS RAM/RTC. */
114 unsigned char rtc_cmos_read(unsigned char addr)
118 lock_cmos_prefix(addr);
119 outb(addr, RTC_PORT(0));
120 val = inb(RTC_PORT(1));
121 lock_cmos_suffix(addr);
125 EXPORT_SYMBOL(rtc_cmos_read);
127 void rtc_cmos_write(unsigned char val, unsigned char addr)
129 lock_cmos_prefix(addr);
130 outb(addr, RTC_PORT(0));
131 outb(val, RTC_PORT(1));
132 lock_cmos_suffix(addr);
134 EXPORT_SYMBOL(rtc_cmos_write);
136 int update_persistent_clock(struct timespec now)
138 return x86_platform.set_wallclock(now.tv_sec);
141 /* not static: needed by APM */
142 void read_persistent_clock(struct timespec *ts)
144 unsigned long retval;
146 retval = x86_platform.get_wallclock();
153 static struct resource rtc_resources[] = {
155 .start = RTC_PORT(0),
157 .flags = IORESOURCE_IO,
162 .flags = IORESOURCE_IRQ,
166 static struct platform_device rtc_device = {
169 .resource = rtc_resources,
170 .num_resources = ARRAY_SIZE(rtc_resources),
173 static __init int add_rtc_cmos(void)
176 static const char * const const ids[] __initconst =
177 { "PNP0b00", "PNP0b01", "PNP0b02", };
182 pnp_for_each_dev(dev) {
183 for (id = dev->id; id; id = id->next) {
184 for (i = 0; i < ARRAY_SIZE(ids); i++) {
185 if (compare_pnp_id(id, ids[i]) != 0)
191 if (of_have_populated_dt())
194 /* Intel MID platforms don't have ioport rtc */
195 if (mrst_identify_cpu())
198 platform_device_register(&rtc_device);
199 dev_info(&rtc_device.dev,
200 "registered platform RTC device (no PNP device found)\n");
204 device_initcall(add_rtc_cmos);