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(const struct timespec
*now
)
43 unsigned long nowtime
= now
->tv_sec
;
47 rtc_time_to_tm(nowtime
, &tm
);
48 if (!rtc_valid_tm(&tm
)) {
49 retval
= set_rtc_time(&tm
);
51 printk(KERN_ERR
"%s: RTC write failed with error %d\n",
52 __FUNCTION__
, retval
);
55 "%s: Invalid RTC value: write of %lx to RTC failed\n",
56 __FUNCTION__
, nowtime
);
62 void mach_get_cmos_time(struct timespec
*now
)
64 unsigned int status
, year
, mon
, day
, hour
, min
, sec
, century
= 0;
67 spin_lock_irqsave(&rtc_lock
, flags
);
70 * If UIP is clear, then we have >= 244 microseconds before
71 * RTC registers will be updated. Spec sheet says that this
72 * is the reliable way to read RTC - registers. If UIP is set
73 * then the register access might be invalid.
75 while ((CMOS_READ(RTC_FREQ_SELECT
) & RTC_UIP
))
78 sec
= CMOS_READ(RTC_SECONDS
);
79 min
= CMOS_READ(RTC_MINUTES
);
80 hour
= CMOS_READ(RTC_HOURS
);
81 day
= CMOS_READ(RTC_DAY_OF_MONTH
);
82 mon
= CMOS_READ(RTC_MONTH
);
83 year
= CMOS_READ(RTC_YEAR
);
86 if (acpi_gbl_FADT
.header
.revision
>= FADT2_REVISION_ID
&&
87 acpi_gbl_FADT
.century
)
88 century
= CMOS_READ(acpi_gbl_FADT
.century
);
91 status
= CMOS_READ(RTC_CONTROL
);
92 WARN_ON_ONCE(RTC_ALWAYS_BCD
&& (status
& RTC_DM_BINARY
));
94 spin_unlock_irqrestore(&rtc_lock
, flags
);
96 if (RTC_ALWAYS_BCD
|| !(status
& RTC_DM_BINARY
)) {
102 year
= bcd2bin(year
);
106 century
= bcd2bin(century
);
107 year
+= century
* 100;
109 year
+= CMOS_YEARS_OFFS
;
111 now
->tv_sec
= mktime(year
, mon
, day
, hour
, min
, sec
);
115 /* Routines for accessing the CMOS RAM/RTC. */
116 unsigned char rtc_cmos_read(unsigned char addr
)
120 lock_cmos_prefix(addr
);
121 outb(addr
, RTC_PORT(0));
122 val
= inb(RTC_PORT(1));
123 lock_cmos_suffix(addr
);
127 EXPORT_SYMBOL(rtc_cmos_read
);
129 void rtc_cmos_write(unsigned char val
, unsigned char addr
)
131 lock_cmos_prefix(addr
);
132 outb(addr
, RTC_PORT(0));
133 outb(val
, RTC_PORT(1));
134 lock_cmos_suffix(addr
);
136 EXPORT_SYMBOL(rtc_cmos_write
);
138 int update_persistent_clock(struct timespec now
)
140 return x86_platform
.set_wallclock(&now
);
143 /* not static: needed by APM */
144 void read_persistent_clock(struct timespec
*ts
)
146 x86_platform
.get_wallclock(ts
);
150 static struct resource rtc_resources
[] = {
152 .start
= RTC_PORT(0),
154 .flags
= IORESOURCE_IO
,
159 .flags
= IORESOURCE_IRQ
,
163 static struct platform_device rtc_device
= {
166 .resource
= rtc_resources
,
167 .num_resources
= ARRAY_SIZE(rtc_resources
),
170 static __init
int add_rtc_cmos(void)
173 static const char * const const ids
[] __initconst
=
174 { "PNP0b00", "PNP0b01", "PNP0b02", };
179 pnp_for_each_dev(dev
) {
180 for (id
= dev
->id
; id
; id
= id
->next
) {
181 for (i
= 0; i
< ARRAY_SIZE(ids
); i
++) {
182 if (compare_pnp_id(id
, ids
[i
]) != 0)
188 if (of_have_populated_dt())
191 /* Intel MID platforms don't have ioport rtc */
192 if (mrst_identify_cpu())
195 platform_device_register(&rtc_device
);
196 dev_info(&rtc_device
.dev
,
197 "registered platform RTC device (no PNP device found)\n");
201 device_initcall(add_rtc_cmos
);