159 lines
3.5 KiB
C
159 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* RTC related functions
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*/
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#include <linux/platform_device.h>
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#include <linux/mc146818rtc.h>
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#include <linux/export.h>
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#include <linux/pnp.h>
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#include <asm/vsyscall.h>
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#include <asm/x86_init.h>
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#include <asm/time.h>
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#include <asm/setup.h>
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#ifdef CONFIG_X86_32
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/*
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* This is a special lock that is owned by the CPU and holds the index
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* register we are working with. It is required for NMI access to the
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* CMOS/RTC registers. See arch/x86/include/asm/mc146818rtc.h for details.
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*/
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volatile unsigned long cmos_lock;
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EXPORT_SYMBOL(cmos_lock);
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#endif /* CONFIG_X86_32 */
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DEFINE_SPINLOCK(rtc_lock);
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EXPORT_SYMBOL(rtc_lock);
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/*
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* In order to set the CMOS clock precisely, mach_set_cmos_time has to be
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* called 500 ms after the second nowtime has started, because when
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* nowtime is written into the registers of the CMOS clock, it will
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* jump to the next second precisely 500 ms later. Check the Motorola
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* MC146818A or Dallas DS12887 data sheet for details.
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*/
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int mach_set_cmos_time(const struct timespec64 *now)
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{
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unsigned long long nowtime = now->tv_sec;
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struct rtc_time tm;
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int retval = 0;
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rtc_time64_to_tm(nowtime, &tm);
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if (!rtc_valid_tm(&tm)) {
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retval = mc146818_set_time(&tm);
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if (retval)
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printk(KERN_ERR "%s: RTC write failed with error %d\n",
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__func__, retval);
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} else {
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printk(KERN_ERR
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"%s: Invalid RTC value: write of %llx to RTC failed\n",
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__func__, nowtime);
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retval = -EINVAL;
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}
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return retval;
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}
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void mach_get_cmos_time(struct timespec64 *now)
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{
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struct rtc_time tm;
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/*
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* If pm_trace abused the RTC as storage, set the timespec to 0,
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* which tells the caller that this RTC value is unusable.
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*/
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if (!pm_trace_rtc_valid()) {
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now->tv_sec = now->tv_nsec = 0;
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return;
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}
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if (mc146818_get_time(&tm, 1000)) {
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pr_err("Unable to read current time from RTC\n");
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now->tv_sec = now->tv_nsec = 0;
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return;
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}
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now->tv_sec = rtc_tm_to_time64(&tm);
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now->tv_nsec = 0;
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}
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/* Routines for accessing the CMOS RAM/RTC. */
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unsigned char rtc_cmos_read(unsigned char addr)
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{
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unsigned char val;
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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val = inb(RTC_PORT(1));
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lock_cmos_suffix(addr);
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return val;
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}
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EXPORT_SYMBOL(rtc_cmos_read);
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void rtc_cmos_write(unsigned char val, unsigned char addr)
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{
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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outb(val, RTC_PORT(1));
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lock_cmos_suffix(addr);
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}
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EXPORT_SYMBOL(rtc_cmos_write);
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int update_persistent_clock64(struct timespec64 now)
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{
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return x86_platform.set_wallclock(&now);
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}
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/* not static: needed by APM */
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void read_persistent_clock64(struct timespec64 *ts)
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{
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x86_platform.get_wallclock(ts);
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}
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static struct resource rtc_resources[] = {
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[0] = {
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.start = RTC_PORT(0),
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.end = RTC_PORT(1),
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.flags = IORESOURCE_IO,
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},
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[1] = {
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.start = RTC_IRQ,
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.end = RTC_IRQ,
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.flags = IORESOURCE_IRQ,
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}
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};
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static struct platform_device rtc_device = {
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.name = "rtc_cmos",
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.id = -1,
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.resource = rtc_resources,
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.num_resources = ARRAY_SIZE(rtc_resources),
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};
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static __init int add_rtc_cmos(void)
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{
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#ifdef CONFIG_PNP
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static const char * const ids[] __initconst =
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{ "PNP0b00", "PNP0b01", "PNP0b02", };
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struct pnp_dev *dev;
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int i;
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pnp_for_each_dev(dev) {
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for (i = 0; i < ARRAY_SIZE(ids); i++) {
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if (compare_pnp_id(dev->id, ids[i]) != 0)
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return 0;
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}
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}
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#endif
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if (!x86_platform.legacy.rtc)
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return -ENODEV;
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platform_device_register(&rtc_device);
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dev_info(&rtc_device.dev,
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"registered platform RTC device (no PNP device found)\n");
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return 0;
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}
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device_initcall(add_rtc_cmos);
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