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 */ 22 volatile unsigned long cmos_lock; 23 EXPORT_SYMBOL(cmos_lock); 24 #endif /* CONFIG_X86_32 */ 25 26 DEFINE_SPINLOCK(rtc_lock); 27 EXPORT_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 */ 36 int 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 57 void 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)) { 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. */ 81 unsigned 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 } 92 EXPORT_SYMBOL(rtc_cmos_read); 93 94 void 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 } 101 EXPORT_SYMBOL(rtc_cmos_write); 102 103 int update_persistent_clock64(struct timespec64 now) 104 { 105 return x86_platform.set_wallclock(&now); 106 } 107 108 /* not static: needed by APM */ 109 void read_persistent_clock64(struct timespec64 *ts) 110 { 111 x86_platform.get_wallclock(ts); 112 } 113 114 115 static 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 }; 127 128 static struct platform_device rtc_device = { 129 .name = "rtc_cmos", 130 .id = -1, 131 .resource = rtc_resources, 132 .num_resources = ARRAY_SIZE(rtc_resources), 133 }; 134 135 static __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 } 159 device_initcall(add_rtc_cmos); 160