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/mrst.h>
  16 #include <asm/rtc.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(unsigned long nowtime)
  42 {
  43         struct rtc_time tm;
  44         int retval = 0;
  45
  46         rtc_time_to_tm(nowtime, &tm);
  47         if (!rtc_valid_tm(&tm)) {
  48                 retval = set_rtc_time(&tm);
  49                 if (retval)
  50                         printk(KERN_ERR "%s: RTC write failed with error %d\n",
  51                                __FUNCTION__, retval);
  52         } else {
  53                 printk(KERN_ERR
  54                        "%s: Invalid RTC value: write of %lx to RTC failed\n",
  55                         __FUNCTION__, nowtime);
  56                 retval = -EINVAL;
  57         }
  58         return retval;
  59 }
  60
  61 unsigned long mach_get_cmos_time(void)
  62 {
  63         unsigned int status, year, mon, day, hour, min, sec, century = 0;
  64         unsigned long flags;
  65
  66         spin_lock_irqsave(&rtc_lock, flags);
  67
  68         /*
  69          * If UIP is clear, then we have >= 244 microseconds before
  70          * RTC registers will be updated.  Spec sheet says that this
  71          * is the reliable way to read RTC - registers. If UIP is set
  72          * then the register access might be invalid.
  73          */
  74         while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
  75                 cpu_relax();
  76
  77         sec = CMOS_READ(RTC_SECONDS);
  78         min = CMOS_READ(RTC_MINUTES);
  79         hour = CMOS_READ(RTC_HOURS);
  80         day = CMOS_READ(RTC_DAY_OF_MONTH);
  81         mon = CMOS_READ(RTC_MONTH);
  82         year = CMOS_READ(RTC_YEAR);
  83
  84 #ifdef CONFIG_ACPI
  85         if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
  86             acpi_gbl_FADT.century)
  87                 century = CMOS_READ(acpi_gbl_FADT.century);
  88 #endif
  89
  90         status = CMOS_READ(RTC_CONTROL);
  91         WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
  92
  93         spin_unlock_irqrestore(&rtc_lock, flags);
  94
  95         if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
  96                 sec = bcd2bin(sec);
  97                 min = bcd2bin(min);
  98                 hour = bcd2bin(hour);
  99                 day = bcd2bin(day);
 100                 mon = bcd2bin(mon);
 101                 year = bcd2bin(year);
 102         }
 103
 104         if (century) {
 105                 century = bcd2bin(century);
 106                 year += century * 100;
 107         } else
 108                 year += CMOS_YEARS_OFFS;
 109
 110         return mktime(year, mon, day, hour, min, sec);
 111 }
 112
 113 /* Routines for accessing the CMOS RAM/RTC. */
 114 unsigned char rtc_cmos_read(unsigned char addr)
 115 {
 116         unsigned char val;
 117
 118         lock_cmos_prefix(addr);
 119         outb(addr, RTC_PORT(0));
 120         val = inb(RTC_PORT(1));
 121         lock_cmos_suffix(addr);
 122
 123         return val;
 124 }
 125 EXPORT_SYMBOL(rtc_cmos_read);
 126
 127 void rtc_cmos_write(unsigned char val, unsigned char addr)
 128 {
 129         lock_cmos_prefix(addr);
 130         outb(addr, RTC_PORT(0));
 131         outb(val, RTC_PORT(1));
 132         lock_cmos_suffix(addr);
 133 }
 134 EXPORT_SYMBOL(rtc_cmos_write);
 135
 136 int update_persistent_clock(struct timespec now)
 137 {
 138         return x86_platform.set_wallclock(now.tv_sec);
 139 }
 140
 141 /* not static: needed by APM */
 142 void read_persistent_clock(struct timespec *ts)
 143 {
 144         unsigned long retval;
 145
 146         retval = x86_platform.get_wallclock();
 147
 148         ts->tv_sec = retval;
 149         ts->tv_nsec = 0;
 150 }
 151
 152
 153 static struct resource rtc_resources[] = {
 154         [0] = {
 155                 .start  = RTC_PORT(0),
 156                 .end    = RTC_PORT(1),
 157                 .flags  = IORESOURCE_IO,
 158         },
 159         [1] = {
 160                 .start  = RTC_IRQ,
 161                 .end    = RTC_IRQ,
 162                 .flags  = IORESOURCE_IRQ,
 163         }
 164 };
 165
 166 static struct platform_device rtc_device = {
 167         .name           = "rtc_cmos",
 168         .id             = -1,
 169         .resource       = rtc_resources,
 170         .num_resources  = ARRAY_SIZE(rtc_resources),
 171 };
 172
 173 static __init int add_rtc_cmos(void)
 174 {
 175 #ifdef CONFIG_PNP
 176         static const char * const  const ids[] __initconst =
 177             { "PNP0b00", "PNP0b01", "PNP0b02", };
 178         struct pnp_dev *dev;
 179         struct pnp_id *id;
 180         int i;
 181
 182         pnp_for_each_dev(dev) {
 183                 for (id = dev->id; id; id = id->next) {
 184                         for (i = 0; i < ARRAY_SIZE(ids); i++) {
 185                                 if (compare_pnp_id(id, ids[i]) != 0)
 186                                         return 0;
 187                         }
 188                 }
 189         }
 190 #endif
 191         if (of_have_populated_dt())
 192                 return 0;
 193
 194         /* Intel MID platforms don't have ioport rtc */
 195         if (mrst_identify_cpu())
 196                 return -ENODEV;
 197
 198         platform_device_register(&rtc_device);
 199         dev_info(&rtc_device.dev,
 200                  "registered platform RTC device (no PNP device found)\n");
 201
 202         return 0;
 203 }
 204 device_initcall(add_rtc_cmos);