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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 
 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         if (paravirt_enabled() && !paravirt_has(RTC))
204                 return -ENODEV;
205 
206         platform_device_register(&rtc_device);
207         dev_info(&rtc_device.dev,
208                  "registered platform RTC device (no PNP device found)\n");
209 
210         return 0;
211 }
212 device_initcall(add_rtc_cmos);
213 

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