1/*
2 * BK Id: %F% %I% %G% %U% %#%
3 */
4/*
5 *  arch/ppc/platforms/chrp_time.c
6 *
7 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
8 *
9 * Adapted for PowerPC (PReP) by Gary Thomas
10 * Modified by Cort Dougan (cort@cs.nmt.edu).
11 * Copied and modified from arch/i386/kernel/time.c
12 *
13 */
14#include <linux/errno.h>
15#include <linux/sched.h>
16#include <linux/kernel.h>
17#include <linux/param.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/interrupt.h>
21#include <linux/time.h>
22#include <linux/timex.h>
23#include <linux/kernel_stat.h>
24#include <linux/mc146818rtc.h>
25#include <linux/init.h>
26
27#include <asm/segment.h>
28#include <asm/io.h>
29#include <asm/processor.h>
30#include <asm/nvram.h>
31#include <asm/prom.h>
32#include <asm/sections.h>
33#include <asm/time.h>
34
35extern spinlock_t rtc_lock;
36
37static int nvram_as1 = NVRAM_AS1;
38static int nvram_as0 = NVRAM_AS0;
39static int nvram_data = NVRAM_DATA;
40
41long __init chrp_time_init(void)
42{
43	struct device_node *rtcs;
44	int base;
45
46	rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
47	if (rtcs == NULL || rtcs->addrs == NULL)
48		return 0;
49	base = rtcs->addrs[0].address;
50	nvram_as1 = 0;
51	nvram_as0 = base;
52	nvram_data = base + 1;
53
54	return 0;
55}
56
57int __chrp chrp_cmos_clock_read(int addr)
58{
59	if (nvram_as1 != 0)
60		outb(addr>>8, nvram_as1);
61	outb(addr, nvram_as0);
62	return (inb(nvram_data));
63}
64
65void __chrp chrp_cmos_clock_write(unsigned long val, int addr)
66{
67	if (nvram_as1 != 0)
68		outb(addr>>8, nvram_as1);
69	outb(addr, nvram_as0);
70	outb(val, nvram_data);
71	return;
72}
73
74/*
75 * Set the hardware clock. -- Cort
76 */
77int __chrp chrp_set_rtc_time(unsigned long nowtime)
78{
79	unsigned char save_control, save_freq_select;
80	struct rtc_time tm;
81
82	spin_lock(&rtc_lock);
83	to_tm(nowtime, &tm);
84
85	save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
86
87	chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
88
89	save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
90
91	chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
92
93        tm.tm_year -= 1900;
94	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
95		BIN_TO_BCD(tm.tm_sec);
96		BIN_TO_BCD(tm.tm_min);
97		BIN_TO_BCD(tm.tm_hour);
98		BIN_TO_BCD(tm.tm_mon);
99		BIN_TO_BCD(tm.tm_mday);
100		BIN_TO_BCD(tm.tm_year);
101	}
102	chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
103	chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
104	chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
105	chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
106	chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
107	chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
108
109	/* The following flags have to be released exactly in this order,
110	 * otherwise the DS12887 (popular MC146818A clone with integrated
111	 * battery and quartz) will not reset the oscillator and will not
112	 * update precisely 500 ms later. You won't find this mentioned in
113	 * the Dallas Semiconductor data sheets, but who believes data
114	 * sheets anyway ...                           -- Markus Kuhn
115	 */
116	chrp_cmos_clock_write(save_control, RTC_CONTROL);
117	chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
118
119	if ( (time_state == TIME_ERROR) || (time_state == TIME_BAD) )
120		time_state = TIME_OK;
121	spin_unlock(&rtc_lock);
122	return 0;
123}
124
125unsigned long __chrp chrp_get_rtc_time(void)
126{
127	unsigned int year, mon, day, hour, min, sec;
128	int uip, i;
129
130	/* The Linux interpretation of the CMOS clock register contents:
131	 * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
132	 * RTC registers show the second which has precisely just started.
133	 * Let's hope other operating systems interpret the RTC the same way.
134	 */
135
136	/* Since the UIP flag is set for about 2.2 ms and the clock
137	 * is typically written with a precision of 1 jiffy, trying
138	 * to obtain a precision better than a few milliseconds is
139	 * an illusion. Only consistency is interesting, this also
140	 * allows to use the routine for /dev/rtc without a potential
141	 * 1 second kernel busy loop triggered by any reader of /dev/rtc.
142	 */
143
144	for ( i = 0; i<1000000; i++) {
145		uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
146		sec = chrp_cmos_clock_read(RTC_SECONDS);
147		min = chrp_cmos_clock_read(RTC_MINUTES);
148		hour = chrp_cmos_clock_read(RTC_HOURS);
149		day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
150		mon = chrp_cmos_clock_read(RTC_MONTH);
151		year = chrp_cmos_clock_read(RTC_YEAR);
152		uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
153		if ((uip & RTC_UIP)==0) break;
154	}
155
156	if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
157	  {
158	    BCD_TO_BIN(sec);
159	    BCD_TO_BIN(min);
160	    BCD_TO_BIN(hour);
161	    BCD_TO_BIN(day);
162	    BCD_TO_BIN(mon);
163	    BCD_TO_BIN(year);
164	  }
165	if ((year += 1900) < 1970)
166		year += 100;
167	return mktime(year, mon, day, hour, min, sec);
168}
169
170
171void __init chrp_calibrate_decr(void)
172{
173	struct device_node *cpu;
174	unsigned int freq, *fp;
175
176	if (via_calibrate_decr())
177		return;
178
179	/*
180	 * The cpu node should have a timebase-frequency property
181	 * to tell us the rate at which the decrementer counts.
182	 */
183	freq = 16666000;		/* hardcoded default */
184	cpu = find_type_devices("cpu");
185	if (cpu != 0) {
186		fp = (unsigned int *)
187			get_property(cpu, "timebase-frequency", NULL);
188		if (fp != 0)
189			freq = *fp;
190	}
191	printk("time_init: decrementer frequency = %u.%.6u MHz\n",
192 	       freq/1000000, freq%1000000);
193	tb_ticks_per_jiffy = freq / HZ;
194	tb_to_us = mulhwu_scale_factor(freq, 1000000);
195}
196