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Linux/arch/x86/kernel/rtc.c

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

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