1 /* 2 * arch/ppc/platforms/chrp_time.c 3 * 4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 5 * 6 * Adapted for PowerPC (PReP) by Gary Thomas 7 * Modified by Cort Dougan (cort@cs.nmt.edu). 8 * Copied and modified from arch/i386/kernel/time.c 9 * 10 */ 11 #include <linux/errno.h> 12 #include <linux/sched.h> 13 #include <linux/kernel.h> 14 #include <linux/param.h> 15 #include <linux/string.h> 16 #include <linux/mm.h> 17 #include <linux/interrupt.h> 18 #include <linux/time.h> 19 #include <linux/timex.h> 20 #include <linux/kernel_stat.h> 21 #include <linux/mc146818rtc.h> 22 #include <linux/init.h> 23 #include <linux/bcd.h> 24 25 #include <asm/io.h> 26 #include <asm/nvram.h> 27 #include <asm/prom.h> 28 #include <asm/sections.h> 29 #include <asm/time.h> 30 31 extern spinlock_t rtc_lock; 32 33 static int nvram_as1 = NVRAM_AS1; 34 static int nvram_as0 = NVRAM_AS0; 35 static int nvram_data = NVRAM_DATA; 36 37 long __init chrp_time_init(void) 38 { 39 struct device_node *rtcs; 40 int base; 41 42 rtcs = find_compatible_devices("rtc", "pnpPNP,b00"); 43 if (rtcs == NULL) 44 rtcs = find_compatible_devices("rtc", "ds1385-rtc"); 45 if (rtcs == NULL || rtcs->addrs == NULL) 46 return 0; 47 base = rtcs->addrs[0].address; 48 nvram_as1 = 0; 49 nvram_as0 = base; 50 nvram_data = base + 1; 51 52 return 0; 53 } 54 55 int chrp_cmos_clock_read(int addr) 56 { 57 if (nvram_as1 != 0) 58 outb(addr>>8, nvram_as1); 59 outb(addr, nvram_as0); 60 return (inb(nvram_data)); 61 } 62 63 void chrp_cmos_clock_write(unsigned long val, int addr) 64 { 65 if (nvram_as1 != 0) 66 outb(addr>>8, nvram_as1); 67 outb(addr, nvram_as0); 68 outb(val, nvram_data); 69 return; 70 } 71 72 /* 73 * Set the hardware clock. -- Cort 74 */ 75 int chrp_set_rtc_time(struct rtc_time *tmarg) 76 { 77 unsigned char save_control, save_freq_select; 78 struct rtc_time tm = *tmarg; 79 80 spin_lock(&rtc_lock); 81 82 save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */ 83 84 chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL); 85 86 save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */ 87 88 chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); 89 90 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 91 BIN_TO_BCD(tm.tm_sec); 92 BIN_TO_BCD(tm.tm_min); 93 BIN_TO_BCD(tm.tm_hour); 94 BIN_TO_BCD(tm.tm_mon); 95 BIN_TO_BCD(tm.tm_mday); 96 BIN_TO_BCD(tm.tm_year); 97 } 98 chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS); 99 chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES); 100 chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS); 101 chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH); 102 chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH); 103 chrp_cmos_clock_write(tm.tm_year,RTC_YEAR); 104 105 /* The following flags have to be released exactly in this order, 106 * otherwise the DS12887 (popular MC146818A clone with integrated 107 * battery and quartz) will not reset the oscillator and will not 108 * update precisely 500 ms later. You won't find this mentioned in 109 * the Dallas Semiconductor data sheets, but who believes data 110 * sheets anyway ... -- Markus Kuhn 111 */ 112 chrp_cmos_clock_write(save_control, RTC_CONTROL); 113 chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT); 114 115 spin_unlock(&rtc_lock); 116 return 0; 117 } 118 119 void chrp_get_rtc_time(struct rtc_time *tm) 120 { 121 unsigned int year, mon, day, hour, min, sec; 122 int uip, i; 123 124 /* The Linux interpretation of the CMOS clock register contents: 125 * When the Update-In-Progress (UIP) flag goes from 1 to 0, the 126 * RTC registers show the second which has precisely just started. 127 * Let's hope other operating systems interpret the RTC the same way. 128 */ 129 130 /* Since the UIP flag is set for about 2.2 ms and the clock 131 * is typically written with a precision of 1 jiffy, trying 132 * to obtain a precision better than a few milliseconds is 133 * an illusion. Only consistency is interesting, this also 134 * allows to use the routine for /dev/rtc without a potential 135 * 1 second kernel busy loop triggered by any reader of /dev/rtc. 136 */ 137 138 for ( i = 0; i<1000000; i++) { 139 uip = chrp_cmos_clock_read(RTC_FREQ_SELECT); 140 sec = chrp_cmos_clock_read(RTC_SECONDS); 141 min = chrp_cmos_clock_read(RTC_MINUTES); 142 hour = chrp_cmos_clock_read(RTC_HOURS); 143 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH); 144 mon = chrp_cmos_clock_read(RTC_MONTH); 145 year = chrp_cmos_clock_read(RTC_YEAR); 146 uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT); 147 if ((uip & RTC_UIP)==0) break; 148 } 149 150 if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 151 BCD_TO_BIN(sec); 152 BCD_TO_BIN(min); 153 BCD_TO_BIN(hour); 154 BCD_TO_BIN(day); 155 BCD_TO_BIN(mon); 156 BCD_TO_BIN(year); 157 } 158 if (year < 70) 159 year += 100; 160 tm->tm_sec = sec; 161 tm->tm_min = min; 162 tm->tm_hour = hour; 163 tm->tm_mday = day; 164 tm->tm_mon = mon; 165 tm->tm_year = year; 166 } 167 168 169 void __init chrp_calibrate_decr(void) 170 { 171 struct device_node *cpu; 172 unsigned int freq, *fp; 173 174 /* 175 * The cpu node should have a timebase-frequency property 176 * to tell us the rate at which the decrementer counts. 177 */ 178 freq = 16666000; /* hardcoded default */ 179 cpu = find_type_devices("cpu"); 180 if (cpu != 0) { 181 fp = (unsigned int *) 182 get_property(cpu, "timebase-frequency", NULL); 183 if (fp != 0) 184 freq = *fp; 185 } 186 ppc_tb_freq = freq; 187 } 188