[ARM] Remove EPXA10DB machine support
[linux-2.6/linux-loongson.git] / arch / ppc / platforms / chrp_time.c
blob29d074c305f05b532b4256b8ab8cb34b3df6480e
1 /*
2 * arch/ppc/platforms/chrp_time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
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
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>
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>
31 extern spinlock_t rtc_lock;
33 static int nvram_as1 = NVRAM_AS1;
34 static int nvram_as0 = NVRAM_AS0;
35 static int nvram_data = NVRAM_DATA;
37 long __init chrp_time_init(void)
39 struct device_node *rtcs;
40 int base;
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;
52 return 0;
55 int chrp_cmos_clock_read(int addr)
57 if (nvram_as1 != 0)
58 outb(addr>>8, nvram_as1);
59 outb(addr, nvram_as0);
60 return (inb(nvram_data));
63 void chrp_cmos_clock_write(unsigned long val, int addr)
65 if (nvram_as1 != 0)
66 outb(addr>>8, nvram_as1);
67 outb(addr, nvram_as0);
68 outb(val, nvram_data);
69 return;
73 * Set the hardware clock. -- Cort
75 int chrp_set_rtc_time(unsigned long nowtime)
77 unsigned char save_control, save_freq_select;
78 struct rtc_time tm;
80 spin_lock(&rtc_lock);
81 to_tm(nowtime, &tm);
83 save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
85 chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
87 save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
89 chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
91 tm.tm_year -= 1900;
92 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
93 BIN_TO_BCD(tm.tm_sec);
94 BIN_TO_BCD(tm.tm_min);
95 BIN_TO_BCD(tm.tm_hour);
96 BIN_TO_BCD(tm.tm_mon);
97 BIN_TO_BCD(tm.tm_mday);
98 BIN_TO_BCD(tm.tm_year);
100 chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
101 chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
102 chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
103 chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
104 chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
105 chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
107 /* The following flags have to be released exactly in this order,
108 * otherwise the DS12887 (popular MC146818A clone with integrated
109 * battery and quartz) will not reset the oscillator and will not
110 * update precisely 500 ms later. You won't find this mentioned in
111 * the Dallas Semiconductor data sheets, but who believes data
112 * sheets anyway ... -- Markus Kuhn
114 chrp_cmos_clock_write(save_control, RTC_CONTROL);
115 chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
117 spin_unlock(&rtc_lock);
118 return 0;
121 unsigned long chrp_get_rtc_time(void)
123 unsigned int year, mon, day, hour, min, sec;
124 int uip, i;
126 /* The Linux interpretation of the CMOS clock register contents:
127 * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
128 * RTC registers show the second which has precisely just started.
129 * Let's hope other operating systems interpret the RTC the same way.
132 /* Since the UIP flag is set for about 2.2 ms and the clock
133 * is typically written with a precision of 1 jiffy, trying
134 * to obtain a precision better than a few milliseconds is
135 * an illusion. Only consistency is interesting, this also
136 * allows to use the routine for /dev/rtc without a potential
137 * 1 second kernel busy loop triggered by any reader of /dev/rtc.
140 for ( i = 0; i<1000000; i++) {
141 uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
142 sec = chrp_cmos_clock_read(RTC_SECONDS);
143 min = chrp_cmos_clock_read(RTC_MINUTES);
144 hour = chrp_cmos_clock_read(RTC_HOURS);
145 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
146 mon = chrp_cmos_clock_read(RTC_MONTH);
147 year = chrp_cmos_clock_read(RTC_YEAR);
148 uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
149 if ((uip & RTC_UIP)==0) break;
152 if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
154 BCD_TO_BIN(sec);
155 BCD_TO_BIN(min);
156 BCD_TO_BIN(hour);
157 BCD_TO_BIN(day);
158 BCD_TO_BIN(mon);
159 BCD_TO_BIN(year);
161 if ((year += 1900) < 1970)
162 year += 100;
163 return mktime(year, mon, day, hour, min, sec);
167 void __init chrp_calibrate_decr(void)
169 struct device_node *cpu;
170 unsigned int freq, *fp;
172 if (via_calibrate_decr())
173 return;
176 * The cpu node should have a timebase-frequency property
177 * to tell us the rate at which the decrementer counts.
179 freq = 16666000; /* hardcoded default */
180 cpu = find_type_devices("cpu");
181 if (cpu != 0) {
182 fp = (unsigned int *)
183 get_property(cpu, "timebase-frequency", NULL);
184 if (fp != 0)
185 freq = *fp;
187 printk("time_init: decrementer frequency = %u.%.6u MHz\n",
188 freq/1000000, freq%1000000);
189 tb_ticks_per_jiffy = freq / HZ;
190 tb_to_us = mulhwu_scale_factor(freq, 1000000);