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/export.h>
   9 #include <linux/pnp.h>
  10 #include <linux/of.h>
  11
  12 #include <asm/vsyscall.h>
  13 #include <asm/x86_init.h>
  14 #include <asm/time.h>
  15 #include <asm/intel-mid.h>
  16 #include <asm/setup.h>
  17
  18 #ifdef CONFIG_X86_32
  19 /*
  20  * This is a special lock that is owned by the CPU and holds the index
  21  * register we are working with.  It is required for NMI access to the
  22  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  23  */
  24 volatile unsigned long cmos_lock;
  25 EXPORT_SYMBOL(cmos_lock);
  26 #endif /* CONFIG_X86_32 */
  27
  28 /* For two digit years assume time is always after that */
  29 #define CMOS_YEARS_OFFS 2000
  30
  31 DEFINE_SPINLOCK(rtc_lock);
  32 EXPORT_SYMBOL(rtc_lock);
  33
  34 /*
  35  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
  36  * called 500 ms after the second nowtime has started, because when
  37  * nowtime is written into the registers of the CMOS clock, it will
  38  * jump to the next second precisely 500 ms later. Check the Motorola
  39  * MC146818A or Dallas DS12887 data sheet for details.
  40  */
  41 int mach_set_rtc_mmss(const struct timespec *now)
  42 {
  43         unsigned long nowtime = now->tv_sec;
  44         struct rtc_time tm;
  45         int retval = 0;
  46
  47         rtc_time_to_tm(nowtime, &tm);
  48         if (!rtc_valid_tm(&tm)) {
  49                 retval = mc146818_set_time(&tm);
  50                 if (retval)
  51                         printk(KERN_ERR "%s: RTC write failed with error %d\n",
  52                                __func__, retval);
  53         } else {
  54                 printk(KERN_ERR
  55                        "%s: Invalid RTC value: write of %lx to RTC failed\n",
  56                         __func__, nowtime);
  57                 retval = -EINVAL;
  58         }
  59         return retval;
  60 }
  61
  62 void mach_get_cmos_time(struct timespec *now)
  63 {
  64         unsigned int status, year, mon, day, hour, min, sec, century = 0;
  65         unsigned long flags;
  66
  67         /*
  68          * If pm_trace abused the RTC as storage, set the timespec to 0,
  69          * which tells the caller that this RTC value is unusable.
  70          */
  71         if (!pm_trace_rtc_valid()) {
  72                 now->tv_sec = now->tv_nsec = 0;
  73                 return;
  74         }
  75
  76         spin_lock_irqsave(&rtc_lock, flags);
  77
  78         /*
  79          * If UIP is clear, then we have >= 244 microseconds before
  80          * RTC registers will be updated.  Spec sheet says that this
  81          * is the reliable way to read RTC - registers. If UIP is set
  82          * then the register access might be invalid.
  83          */
  84         while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
  85                 cpu_relax();
  86
  87         sec = CMOS_READ(RTC_SECONDS);
  88         min = CMOS_READ(RTC_MINUTES);
  89         hour = CMOS_READ(RTC_HOURS);
  90         day = CMOS_READ(RTC_DAY_OF_MONTH);
  91         mon = CMOS_READ(RTC_MONTH);
  92         year = CMOS_READ(RTC_YEAR);
  93
  94 #ifdef CONFIG_ACPI
  95         if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
  96             acpi_gbl_FADT.century)
  97                 century = CMOS_READ(acpi_gbl_FADT.century);
  98 #endif
  99
 100         status = CMOS_READ(RTC_CONTROL);
 101         WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
 102
 103         spin_unlock_irqrestore(&rtc_lock, flags);
 104
 105         if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
 106                 sec = bcd2bin(sec);
 107                 min = bcd2bin(min);
 108                 hour = bcd2bin(hour);
 109                 day = bcd2bin(day);
 110                 mon = bcd2bin(mon);
 111                 year = bcd2bin(year);
 112         }
 113
 114         if (century) {
 115                 century = bcd2bin(century);
 116                 year += century * 100;
 117         } else
 118                 year += CMOS_YEARS_OFFS;
 119
 120         now->tv_sec = mktime(year, mon, day, hour, min, sec);
 121         now->tv_nsec = 0;
 122 }
 123
 124 /* Routines for accessing the CMOS RAM/RTC. */
 125 unsigned char rtc_cmos_read(unsigned char addr)
 126 {
 127         unsigned char val;
 128
 129         lock_cmos_prefix(addr);
 130         outb(addr, RTC_PORT(0));
 131         val = inb(RTC_PORT(1));
 132         lock_cmos_suffix(addr);
 133
 134         return val;
 135 }
 136 EXPORT_SYMBOL(rtc_cmos_read);
 137
 138 void rtc_cmos_write(unsigned char val, unsigned char addr)
 139 {
 140         lock_cmos_prefix(addr);
 141         outb(addr, RTC_PORT(0));
 142         outb(val, RTC_PORT(1));
 143         lock_cmos_suffix(addr);
 144 }
 145 EXPORT_SYMBOL(rtc_cmos_write);
 146
 147 int update_persistent_clock(struct timespec now)
 148 {
 149         return x86_platform.set_wallclock(&now);
 150 }
 151
 152 /* not static: needed by APM */
 153 void read_persistent_clock(struct timespec *ts)
 154 {
 155         x86_platform.get_wallclock(ts);
 156 }
 157
 158
 159 static struct resource rtc_resources[] = {
 160         [0] = {
 161                 .start  = RTC_PORT(0),
 162                 .end    = RTC_PORT(1),
 163                 .flags  = IORESOURCE_IO,
 164         },
 165         [1] = {
 166                 .start  = RTC_IRQ,
 167                 .end    = RTC_IRQ,
 168                 .flags  = IORESOURCE_IRQ,
 169         }
 170 };
 171
 172 static struct platform_device rtc_device = {
 173         .name           = "rtc_cmos",
 174         .id             = -1,
 175         .resource       = rtc_resources,
 176         .num_resources  = ARRAY_SIZE(rtc_resources),
 177 };
 178
 179 static __init int add_rtc_cmos(void)
 180 {
 181 #ifdef CONFIG_PNP
 182         static const char * const ids[] __initconst =
 183             { "PNP0b00", "PNP0b01", "PNP0b02", };
 184         struct pnp_dev *dev;
 185         struct pnp_id *id;
 186         int i;
 187
 188         pnp_for_each_dev(dev) {
 189                 for (id = dev->id; id; id = id->next) {
 190                         for (i = 0; i < ARRAY_SIZE(ids); i++) {
 191                                 if (compare_pnp_id(id, ids[i]) != 0)
 192                                         return 0;
 193                         }
 194                 }
 195         }
 196 #endif
 197         if (!x86_platform.legacy.rtc)
 198                 return -ENODEV;
 199
 200         platform_device_register(&rtc_device);
 201         dev_info(&rtc_device.dev,
 202                  "registered platform RTC device (no PNP device found)\n");
 203
 204         return 0;
 205 }
 206 device_initcall(add_rtc_cmos);