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// SPDX-License-Identifier: GPL-2.0
/*
* RTC related functions
*/
#include <linux/platform_device.h>
#include <linux/mc146818rtc.h>
#include <linux/export.h>
#include <linux/pnp.h>
#include <asm/vsyscall.h>
#include <asm/x86_init.h>
#include <asm/time.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 arch/x86/include/asm/mc146818rtc.h for details.
*/
volatile unsigned long cmos_lock;
EXPORT_SYMBOL(cmos_lock);
#endif /* CONFIG_X86_32 */
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
/*
* In order to set the CMOS clock precisely, mach_set_cmos_time 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_cmos_time(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)
{
struct rtc_time tm;
/*
* 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;
}
if (mc146818_get_time(&tm, 1000)) {
pr_err("Unable to read current time from RTC\n");
now->tv_sec = now->tv_nsec = 0;
return;
}
now->tv_sec = rtc_tm_to_time64(&tm);
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;
int i;
pnp_for_each_dev(dev) {
for (i = 0; i < ARRAY_SIZE(ids); i++) {
if (compare_pnp_id(dev->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);
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