1 /* 2 * RTC related functions 3 */ 4 #include <linux/acpi.h> 5 #include <linux/bcd.h> 6 #include <linux/mc146818rtc.h> 7 #include <linux/platform_device.h> 8 #include <linux/pnp.h> 9 10 #include <asm/time.h> 11 #include <asm/vsyscall.h> 12 13 #ifdef CONFIG_X86_32 14 /* 15 * This is a special lock that is owned by the CPU and holds the index 16 * register we are working with. It is required for NMI access to the 17 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. 18 */ 19 volatile unsigned long cmos_lock = 0; 20 EXPORT_SYMBOL(cmos_lock); 21 #endif 22 23 /* For two digit years assume time is always after that */ 24 #define CMOS_YEARS_OFFS 2000 25 26 DEFINE_SPINLOCK(rtc_lock); 27 EXPORT_SYMBOL(rtc_lock); 28 29 /* 30 * In order to set the CMOS clock precisely, set_rtc_mmss 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 * BUG: This routine does not handle hour overflow properly; it just 37 * sets the minutes. Usually you'll only notice that after reboot! 38 */ 39 int mach_set_rtc_mmss(unsigned long nowtime) 40 { 41 int retval = 0; 42 int real_seconds, real_minutes, cmos_minutes; 43 unsigned char save_control, save_freq_select; 44 45 /* tell the clock it's being set */ 46 save_control = CMOS_READ(RTC_CONTROL); 47 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); 48 49 /* stop and reset prescaler */ 50 save_freq_select = CMOS_READ(RTC_FREQ_SELECT); 51 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); 52 53 cmos_minutes = CMOS_READ(RTC_MINUTES); 54 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) 55 cmos_minutes = bcd2bin(cmos_minutes); 56 57 /* 58 * since we're only adjusting minutes and seconds, 59 * don't interfere with hour overflow. This avoids 60 * messing with unknown time zones but requires your 61 * RTC not to be off by more than 15 minutes 62 */ 63 real_seconds = nowtime % 60; 64 real_minutes = nowtime / 60; 65 /* correct for half hour time zone */ 66 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) 67 real_minutes += 30; 68 real_minutes %= 60; 69 70 if (abs(real_minutes - cmos_minutes) < 30) { 71 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 72 real_seconds = bin2bcd(real_seconds); 73 real_minutes = bin2bcd(real_minutes); 74 } 75 CMOS_WRITE(real_seconds,RTC_SECONDS); 76 CMOS_WRITE(real_minutes,RTC_MINUTES); 77 } else { 78 printk(KERN_WARNING 79 "set_rtc_mmss: can't update from %d to %d\n", 80 cmos_minutes, real_minutes); 81 retval = -1; 82 } 83 84 /* The following flags have to be released exactly in this order, 85 * otherwise the DS12887 (popular MC146818A clone with integrated 86 * battery and quartz) will not reset the oscillator and will not 87 * update precisely 500 ms later. You won't find this mentioned in 88 * the Dallas Semiconductor data sheets, but who believes data 89 * sheets anyway ... -- Markus Kuhn 90 */ 91 CMOS_WRITE(save_control, RTC_CONTROL); 92 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); 93 94 return retval; 95 } 96 97 unsigned long mach_get_cmos_time(void) 98 { 99 unsigned int status, year, mon, day, hour, min, sec, century = 0; 100 101 /* 102 * If UIP is clear, then we have >= 244 microseconds before 103 * RTC registers will be updated. Spec sheet says that this 104 * is the reliable way to read RTC - registers. If UIP is set 105 * then the register access might be invalid. 106 */ 107 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) 108 cpu_relax(); 109 110 sec = CMOS_READ(RTC_SECONDS); 111 min = CMOS_READ(RTC_MINUTES); 112 hour = CMOS_READ(RTC_HOURS); 113 day = CMOS_READ(RTC_DAY_OF_MONTH); 114 mon = CMOS_READ(RTC_MONTH); 115 year = CMOS_READ(RTC_YEAR); 116 117 #ifdef CONFIG_ACPI 118 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && 119 acpi_gbl_FADT.century) 120 century = CMOS_READ(acpi_gbl_FADT.century); 121 #endif 122 123 status = CMOS_READ(RTC_CONTROL); 124 WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY)); 125 126 if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) { 127 sec = bcd2bin(sec); 128 min = bcd2bin(min); 129 hour = bcd2bin(hour); 130 day = bcd2bin(day); 131 mon = bcd2bin(mon); 132 year = bcd2bin(year); 133 } 134 135 if (century) { 136 century = bcd2bin(century); 137 year += century * 100; 138 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100); 139 } else 140 year += CMOS_YEARS_OFFS; 141 142 return mktime(year, mon, day, hour, min, sec); 143 } 144 145 /* Routines for accessing the CMOS RAM/RTC. */ 146 unsigned char rtc_cmos_read(unsigned char addr) 147 { 148 unsigned char val; 149 150 lock_cmos_prefix(addr); 151 outb(addr, RTC_PORT(0)); 152 val = inb(RTC_PORT(1)); 153 lock_cmos_suffix(addr); 154 return val; 155 } 156 EXPORT_SYMBOL(rtc_cmos_read); 157 158 void rtc_cmos_write(unsigned char val, unsigned char addr) 159 { 160 lock_cmos_prefix(addr); 161 outb(addr, RTC_PORT(0)); 162 outb(val, RTC_PORT(1)); 163 lock_cmos_suffix(addr); 164 } 165 EXPORT_SYMBOL(rtc_cmos_write); 166 167 static int set_rtc_mmss(unsigned long nowtime) 168 { 169 int retval; 170 unsigned long flags; 171 172 spin_lock_irqsave(&rtc_lock, flags); 173 retval = set_wallclock(nowtime); 174 spin_unlock_irqrestore(&rtc_lock, flags); 175 176 return retval; 177 } 178 179 /* not static: needed by APM */ 180 unsigned long read_persistent_clock(void) 181 { 182 unsigned long retval, flags; 183 184 spin_lock_irqsave(&rtc_lock, flags); 185 retval = get_wallclock(); 186 spin_unlock_irqrestore(&rtc_lock, flags); 187 188 return retval; 189 } 190 191 int update_persistent_clock(struct timespec now) 192 { 193 return set_rtc_mmss(now.tv_sec); 194 } 195 196 unsigned long long native_read_tsc(void) 197 { 198 return __native_read_tsc(); 199 } 200 EXPORT_SYMBOL(native_read_tsc); 201 202 203 static struct resource rtc_resources[] = { 204 [0] = { 205 .start = RTC_PORT(0), 206 .end = RTC_PORT(1), 207 .flags = IORESOURCE_IO, 208 }, 209 [1] = { 210 .start = RTC_IRQ, 211 .end = RTC_IRQ, 212 .flags = IORESOURCE_IRQ, 213 } 214 }; 215 216 static struct platform_device rtc_device = { 217 .name = "rtc_cmos", 218 .id = -1, 219 .resource = rtc_resources, 220 .num_resources = ARRAY_SIZE(rtc_resources), 221 }; 222 223 static __init int add_rtc_cmos(void) 224 { 225 #ifdef CONFIG_PNP 226 static const char *ids[] __initconst = 227 { "PNP0b00", "PNP0b01", "PNP0b02", }; 228 struct pnp_dev *dev; 229 struct pnp_id *id; 230 int i; 231 232 pnp_for_each_dev(dev) { 233 for (id = dev->id; id; id = id->next) { 234 for (i = 0; i < ARRAY_SIZE(ids); i++) { 235 if (compare_pnp_id(id, ids[i]) != 0) 236 return 0; 237 } 238 } 239 } 240 #endif 241 242 platform_device_register(&rtc_device); 243 dev_info(&rtc_device.dev, 244 "registered platform RTC device (no PNP device found)\n"); 245 return 0; 246 } 247 device_initcall(add_rtc_cmos); 248