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/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(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 = set_rtc_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         spin_lock_irqsave(&rtc_lock, flags);
  68
  69         /*
  70          * If UIP is clear, then we have >= 244 microseconds before
  71          * RTC registers will be updated.  Spec sheet says that this
  72          * is the reliable way to read RTC - registers. If UIP is set
  73          * then the register access might be invalid.
  74          */
  75         while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
  76                 cpu_relax();
  77
  78         sec = CMOS_READ(RTC_SECONDS);
  79         min = CMOS_READ(RTC_MINUTES);
  80         hour = CMOS_READ(RTC_HOURS);
  81         day = CMOS_READ(RTC_DAY_OF_MONTH);
  82         mon = CMOS_READ(RTC_MONTH);
  83         year = CMOS_READ(RTC_YEAR);
  84
  85 #ifdef CONFIG_ACPI
  86         if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
  87             acpi_gbl_FADT.century)
  88                 century = CMOS_READ(acpi_gbl_FADT.century);
  89 #endif
  90
  91         status = CMOS_READ(RTC_CONTROL);
  92         WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
  93
  94         spin_unlock_irqrestore(&rtc_lock, flags);
  95
  96         if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
  97                 sec = bcd2bin(sec);
  98                 min = bcd2bin(min);
  99                 hour = bcd2bin(hour);
 100                 day = bcd2bin(day);
 101                 mon = bcd2bin(mon);
 102                 year = bcd2bin(year);
 103         }
 104
 105         if (century) {
 106                 century = bcd2bin(century);
 107                 year += century * 100;
 108         } else
 109                 year += CMOS_YEARS_OFFS;
 110
 111         now->tv_sec = mktime(year, mon, day, hour, min, sec);
 112         now->tv_nsec = 0;
 113 }
 114
 115 /* Routines for accessing the CMOS RAM/RTC. */
 116 unsigned char rtc_cmos_read(unsigned char addr)
 117 {
 118         unsigned char val;
 119
 120         lock_cmos_prefix(addr);
 121         outb(addr, RTC_PORT(0));
 122         val = inb(RTC_PORT(1));
 123         lock_cmos_suffix(addr);
 124
 125         return val;
 126 }
 127 EXPORT_SYMBOL(rtc_cmos_read);
 128
 129 void rtc_cmos_write(unsigned char val, unsigned char addr)
 130 {
 131         lock_cmos_prefix(addr);
 132         outb(addr, RTC_PORT(0));
 133         outb(val, RTC_PORT(1));
 134         lock_cmos_suffix(addr);
 135 }
 136 EXPORT_SYMBOL(rtc_cmos_write);
 137
 138 int update_persistent_clock(struct timespec now)
 139 {
 140         return x86_platform.set_wallclock(&now);
 141 }
 142
 143 /* not static: needed by APM */
 144 void read_persistent_clock(struct timespec *ts)
 145 {
 146         x86_platform.get_wallclock(ts);
 147 }
 148
 149
 150 static struct resource rtc_resources[] = {
 151         [0] = {
 152                 .start  = RTC_PORT(0),
 153                 .end    = RTC_PORT(1),
 154                 .flags  = IORESOURCE_IO,
 155         },
 156         [1] = {
 157                 .start  = RTC_IRQ,
 158                 .end    = RTC_IRQ,
 159                 .flags  = IORESOURCE_IRQ,
 160         }
 161 };
 162
 163 static struct platform_device rtc_device = {
 164         .name           = "rtc_cmos",
 165         .id             = -1,
 166         .resource       = rtc_resources,
 167         .num_resources  = ARRAY_SIZE(rtc_resources),
 168 };
 169
 170 static __init int add_rtc_cmos(void)
 171 {
 172 #ifdef CONFIG_PNP
 173         static const char * const ids[] __initconst =
 174             { "PNP0b00", "PNP0b01", "PNP0b02", };
 175         struct pnp_dev *dev;
 176         struct pnp_id *id;
 177         int i;
 178
 179         pnp_for_each_dev(dev) {
 180                 for (id = dev->id; id; id = id->next) {
 181                         for (i = 0; i < ARRAY_SIZE(ids); i++) {
 182                                 if (compare_pnp_id(id, ids[i]) != 0)
 183                                         return 0;
 184                         }
 185                 }
 186         }
 187 #endif
 188         if (of_have_populated_dt())
 189                 return 0;
 190
 191         /* Intel MID platforms don't have ioport rtc */
 192         if (intel_mid_identify_cpu())
 193                 return -ENODEV;
 194
 195 #ifdef CONFIG_ACPI
 196         if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
 197                 /* This warning can likely go away again in a year or two. */
 198                 pr_info("ACPI: not registering RTC platform device\n");
 199                 return -ENODEV;
 200         }
 201 #endif
 202
 203         platform_device_register(&rtc_device);
 204         dev_info(&rtc_device.dev,
 205                  "registered platform RTC device (no PNP device found)\n");
 206
 207         return 0;
 208 }
 209 device_initcall(add_rtc_cmos);