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