arch/x86/kernel/rtc.c

   1 /*
   2  * RTC related functions
   3  */
   4 #include <linux/platform_device.h>
   5 #include <linux/mc146818rtc.h>
   6 #include <linux/acpi.h>
   7 #include <linux/bcd.h>
   8 #include <linux/pnp.h>
   9
  10 #include <asm/vsyscall.h>
  11 #include <asm/x86_init.h>
  12 #include <asm/time.h>
  13
  14 #ifdef CONFIG_X86_32
  15 /*
  16  * This is a special lock that is owned by the CPU and holds the index
  17  * register we are working with.  It is required for NMI access to the
  18  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  19  */
  20 volatile unsigned long cmos_lock;
  21 EXPORT_SYMBOL(cmos_lock);
  22 #endif /* CONFIG_X86_32 */
  23
  24 /* For two digit years assume time is always after that */
  25 #define CMOS_YEARS_OFFS 2000
  26
  27 DEFINE_SPINLOCK(rtc_lock);
  28 EXPORT_SYMBOL(rtc_lock);
  29
  30 /*
  31  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
  32  * called 500 ms after the second nowtime has started, because when
  33  * nowtime is written into the registers of the CMOS clock, it will
  34  * jump to the next second precisely 500 ms later. Check the Motorola
  35  * MC146818A or Dallas DS12887 data sheet for details.
  36  *
  37  * BUG: This routine does not handle hour overflow properly; it just
  38  *      sets the minutes. Usually you'll only notice that after reboot!
  39  */
  40 int mach_set_rtc_mmss(unsigned long nowtime)
  41 {
  42         int real_seconds, real_minutes, cmos_minutes;
  43         unsigned char save_control, save_freq_select;
  44         int retval = 0;
  45
  46          /* tell the clock it's being set */
  47         save_control = CMOS_READ(RTC_CONTROL);
  48         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
  49
  50         /* stop and reset prescaler */
  51         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  52         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  53
  54         cmos_minutes = CMOS_READ(RTC_MINUTES);
  55         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  56                 cmos_minutes = bcd2bin(cmos_minutes);
  57
  58         /*
  59          * since we're only adjusting minutes and seconds,
  60          * don't interfere with hour overflow. This avoids
  61          * messing with unknown time zones but requires your
  62          * RTC not to be off by more than 15 minutes
  63          */
  64         real_seconds = nowtime % 60;
  65         real_minutes = nowtime / 60;
  66         /* correct for half hour time zone */
  67         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
  68                 real_minutes += 30;
  69         real_minutes %= 60;
  70
  71         if (abs(real_minutes - cmos_minutes) < 30) {
  72                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  73                         real_seconds = bin2bcd(real_seconds);
  74                         real_minutes = bin2bcd(real_minutes);
  75                 }
  76                 CMOS_WRITE(real_seconds, RTC_SECONDS);
  77                 CMOS_WRITE(real_minutes, RTC_MINUTES);
  78         } else {
  79                 printk(KERN_WARNING
  80                        "set_rtc_mmss: can't update from %d to %d\n",
  81                        cmos_minutes, real_minutes);
  82                 retval = -1;
  83         }
  84
  85         /* The following flags have to be released exactly in this order,
  86          * otherwise the DS12887 (popular MC146818A clone with integrated
  87          * battery and quartz) will not reset the oscillator and will not
  88          * update precisely 500 ms later. You won't find this mentioned in
  89          * the Dallas Semiconductor data sheets, but who believes data
  90          * sheets anyway ...                           -- Markus Kuhn
  91          */
  92         CMOS_WRITE(save_control, RTC_CONTROL);
  93         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
  94
  95         return retval;
  96 }
  97
  98 unsigned long mach_get_cmos_time(void)
  99 {
 100         unsigned int status, year, mon, day, hour, min, sec, century = 0;
 101
 102         /*
 103          * If UIP is clear, then we have >= 244 microseconds before
 104          * RTC registers will be updated.  Spec sheet says that this
 105          * is the reliable way to read RTC - registers. If UIP is set
 106          * then the register access might be invalid.
 107          */
 108         while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
 109                 cpu_relax();
 110
 111         sec = CMOS_READ(RTC_SECONDS);
 112         min = CMOS_READ(RTC_MINUTES);
 113         hour = CMOS_READ(RTC_HOURS);
 114         day = CMOS_READ(RTC_DAY_OF_MONTH);
 115         mon = CMOS_READ(RTC_MONTH);
 116         year = CMOS_READ(RTC_YEAR);
 117
 118 #ifdef CONFIG_ACPI
 119         if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
 120             acpi_gbl_FADT.century)
 121                 century = CMOS_READ(acpi_gbl_FADT.century);
 122 #endif
 123
 124         status = CMOS_READ(RTC_CONTROL);
 125         WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
 126
 127         if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
 128                 sec = bcd2bin(sec);
 129                 min = bcd2bin(min);
 130                 hour = bcd2bin(hour);
 131                 day = bcd2bin(day);
 132                 mon = bcd2bin(mon);
 133                 year = bcd2bin(year);
 134         }
 135
 136         if (century) {
 137                 century = bcd2bin(century);
 138                 year += century * 100;
 139                 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
 140         } else
 141                 year += CMOS_YEARS_OFFS;
 142
 143         return mktime(year, mon, day, hour, min, sec);
 144 }
 145
 146 /* Routines for accessing the CMOS RAM/RTC. */
 147 unsigned char rtc_cmos_read(unsigned char addr)
 148 {
 149         unsigned char val;
 150
 151         lock_cmos_prefix(addr);
 152         outb(addr, RTC_PORT(0));
 153         val = inb(RTC_PORT(1));
 154         lock_cmos_suffix(addr);
 155
 156         return val;
 157 }
 158 EXPORT_SYMBOL(rtc_cmos_read);
 159
 160 void rtc_cmos_write(unsigned char val, unsigned char addr)
 161 {
 162         lock_cmos_prefix(addr);
 163         outb(addr, RTC_PORT(0));
 164         outb(val, RTC_PORT(1));
 165         lock_cmos_suffix(addr);
 166 }
 167 EXPORT_SYMBOL(rtc_cmos_write);
 168
 169 int update_persistent_clock(struct timespec now)
 170 {
 171         unsigned long flags;
 172         int retval;
 173
 174         spin_lock_irqsave(&rtc_lock, flags);
 175         retval = x86_platform.set_wallclock(now.tv_sec);
 176         spin_unlock_irqrestore(&rtc_lock, flags);
 177
 178         return retval;
 179 }
 180
 181 /* not static: needed by APM */
 182 void read_persistent_clock(struct timespec *ts)
 183 {
 184         unsigned long retval, flags;
 185
 186         spin_lock_irqsave(&rtc_lock, flags);
 187         retval = x86_platform.get_wallclock();
 188         spin_unlock_irqrestore(&rtc_lock, flags);
 189
 190         ts->tv_sec = retval;
 191         ts->tv_nsec = 0;
 192 }
 193
 194 unsigned long long native_read_tsc(void)
 195 {
 196         return __native_read_tsc();
 197 }
 198 EXPORT_SYMBOL(native_read_tsc);
 199
 200
 201 static struct resource rtc_resources[] = {
 202         [0] = {
 203                 .start  = RTC_PORT(0),
 204                 .end    = RTC_PORT(1),
 205                 .flags  = IORESOURCE_IO,
 206         },
 207         [1] = {
 208                 .start  = RTC_IRQ,
 209                 .end    = RTC_IRQ,
 210                 .flags  = IORESOURCE_IRQ,
 211         }
 212 };
 213
 214 static struct platform_device rtc_device = {
 215         .name           = "rtc_cmos",
 216         .id             = -1,
 217         .resource       = rtc_resources,
 218         .num_resources  = ARRAY_SIZE(rtc_resources),
 219 };
 220
 221 static __init int add_rtc_cmos(void)
 222 {
 223 #ifdef CONFIG_PNP
 224         static const char *ids[] __initconst =
 225             { "PNP0b00", "PNP0b01", "PNP0b02", };
 226         struct pnp_dev *dev;
 227         struct pnp_id *id;
 228         int i;
 229
 230         pnp_for_each_dev(dev) {
 231                 for (id = dev->id; id; id = id->next) {
 232                         for (i = 0; i < ARRAY_SIZE(ids); i++) {
 233                                 if (compare_pnp_id(id, ids[i]) != 0)
 234                                         return 0;
 235                         }
 236                 }
 237         }
 238 #endif
 239
 240         platform_device_register(&rtc_device);
 241         dev_info(&rtc_device.dev,
 242                  "registered platform RTC device (no PNP device found)\n");
 243
 244         return 0;
 245 }
 246 device_initcall(add_rtc_cmos);