1// SPDX-License-Identifier: GPL-2.0 2/* 3 * RTC related functions 4 */ 5#include <linux/platform_device.h> 6#include <linux/mc146818rtc.h> 7#include <linux/export.h> 8#include <linux/pnp.h> 9 10#include <asm/vsyscall.h> 11#include <asm/x86_init.h> 12#include <asm/time.h> 13#include <asm/intel-mid.h> 14#include <asm/setup.h> 15 16#ifdef CONFIG_X86_32 17/* 18 * This is a special lock that is owned by the CPU and holds the index 19 * register we are working with. It is required for NMI access to the 20 * CMOS/RTC registers. See arch/x86/include/asm/mc146818rtc.h for details. 21 */ 22volatile unsigned long cmos_lock; 23EXPORT_SYMBOL(cmos_lock); 24#endif /* CONFIG_X86_32 */ 25 26DEFINE_SPINLOCK(rtc_lock); 27EXPORT_SYMBOL(rtc_lock); 28 29/* 30 * In order to set the CMOS clock precisely, mach_set_cmos_time has to be 31 * called 500 ms after the second nowtime has started, because when 32 * nowtime is written into the registers of the CMOS clock, it will 33 * jump to the next second precisely 500 ms later. Check the Motorola 34 * MC146818A or Dallas DS12887 data sheet for details. 35 */ 36int mach_set_cmos_time(const struct timespec64 *now) 37{ 38 unsigned long long nowtime = now->tv_sec; 39 struct rtc_time tm; 40 int retval = 0; 41 42 rtc_time64_to_tm(nowtime, &tm); 43 if (!rtc_valid_tm(&tm)) { 44 retval = mc146818_set_time(&tm); 45 if (retval) 46 printk(KERN_ERR "%s: RTC write failed with error %d\n", 47 __func__, retval); 48 } else { 49 printk(KERN_ERR 50 "%s: Invalid RTC value: write of %llx to RTC failed\n", 51 __func__, nowtime); 52 retval = -EINVAL; 53 } 54 return retval; 55} 56 57void mach_get_cmos_time(struct timespec64 *now) 58{ 59 struct rtc_time tm; 60 61 /* 62 * If pm_trace abused the RTC as storage, set the timespec to 0, 63 * which tells the caller that this RTC value is unusable. 64 */ 65 if (!pm_trace_rtc_valid()) { 66 now->tv_sec = now->tv_nsec = 0; 67 return; 68 } 69 70 if (mc146818_get_time(&tm, 1000)) { 71 pr_err("Unable to read current time from RTC\n"); 72 now->tv_sec = now->tv_nsec = 0; 73 return; 74 } 75 76 now->tv_sec = rtc_tm_to_time64(&tm); 77 now->tv_nsec = 0; 78} 79 80/* Routines for accessing the CMOS RAM/RTC. */ 81unsigned char rtc_cmos_read(unsigned char addr) 82{ 83 unsigned char val; 84 85 lock_cmos_prefix(addr); 86 outb(addr, RTC_PORT(0)); 87 val = inb(RTC_PORT(1)); 88 lock_cmos_suffix(addr); 89 90 return val; 91} 92EXPORT_SYMBOL(rtc_cmos_read); 93 94void rtc_cmos_write(unsigned char val, unsigned char addr) 95{ 96 lock_cmos_prefix(addr); 97 outb(addr, RTC_PORT(0)); 98 outb(val, RTC_PORT(1)); 99 lock_cmos_suffix(addr); 100} 101EXPORT_SYMBOL(rtc_cmos_write); 102 103int update_persistent_clock64(struct timespec64 now) 104{ 105 return x86_platform.set_wallclock(&now); 106} 107 108/* not static: needed by APM */ 109void read_persistent_clock64(struct timespec64 *ts) 110{ 111 x86_platform.get_wallclock(ts); 112} 113 114 115static struct resource rtc_resources[] = { 116 [0] = { 117 .start = RTC_PORT(0), 118 .end = RTC_PORT(1), 119 .flags = IORESOURCE_IO, 120 }, 121 [1] = { 122 .start = RTC_IRQ, 123 .end = RTC_IRQ, 124 .flags = IORESOURCE_IRQ, 125 } 126}; 127 128static struct platform_device rtc_device = { 129 .name = "rtc_cmos", 130 .id = -1, 131 .resource = rtc_resources, 132 .num_resources = ARRAY_SIZE(rtc_resources), 133}; 134 135static __init int add_rtc_cmos(void) 136{ 137#ifdef CONFIG_PNP 138 static const char * const ids[] __initconst = 139 { "PNP0b00", "PNP0b01", "PNP0b02", }; 140 struct pnp_dev *dev; 141 int i; 142 143 pnp_for_each_dev(dev) { 144 for (i = 0; i < ARRAY_SIZE(ids); i++) { 145 if (compare_pnp_id(dev->id, ids[i]) != 0) 146 return 0; 147 } 148 } 149#endif 150 if (!x86_platform.legacy.rtc) 151 return -ENODEV; 152 153 platform_device_register(&rtc_device); 154 dev_info(&rtc_device.dev, 155 "registered platform RTC device (no PNP device found)\n"); 156 157 return 0; 158} 159device_initcall(add_rtc_cmos); 160