/arch/ppc64/kernel/maple_time.c

  1/*
  2 *  arch/ppc64/kernel/maple_time.c
  3 *
  4 *  (c) Copyright 2004 Benjamin Herrenschmidt (benh@kernel.crashing.org),
  5 *                     IBM Corp. 
  6 *
  7 *  This program is free software; you can redistribute it and/or
  8 *  modify it under the terms of the GNU General Public License
  9 *  as published by the Free Software Foundation; either version
 10 *  2 of the License, or (at your option) any later version.
 11 *
 12 */
 13
 14#undef DEBUG
 15
 16#include <linux/config.h>
 17#include <linux/errno.h>
 18#include <linux/sched.h>
 19#include <linux/kernel.h>
 20#include <linux/param.h>
 21#include <linux/string.h>
 22#include <linux/mm.h>
 23#include <linux/init.h>
 24#include <linux/time.h>
 25#include <linux/adb.h>
 26#include <linux/pmu.h>
 27#include <linux/interrupt.h>
 28#include <linux/mc146818rtc.h>
 29#include <linux/bcd.h>
 30
 31#include <asm/sections.h>
 32#include <asm/prom.h>
 33#include <asm/system.h>
 34#include <asm/io.h>
 35#include <asm/pgtable.h>
 36#include <asm/machdep.h>
 37#include <asm/time.h>
 38
 39#ifdef DEBUG
 40#define DBG(x...) printk(x)
 41#else
 42#define DBG(x...)
 43#endif
 44
 45extern void setup_default_decr(void);
 46extern void GregorianDay(struct rtc_time * tm);
 47
 48extern unsigned long ppc_tb_freq;
 49extern unsigned long ppc_proc_freq;
 50static int maple_rtc_addr;
 51
 52static int maple_clock_read(int addr)
 53{
 54	outb_p(addr, maple_rtc_addr);
 55	return inb_p(maple_rtc_addr+1);
 56}
 57
 58static void maple_clock_write(unsigned long val, int addr)
 59{
 60	outb_p(addr, maple_rtc_addr);
 61	outb_p(val, maple_rtc_addr+1);
 62}
 63
 64void maple_get_rtc_time(struct rtc_time *tm)
 65{
 66	int uip, i;
 67
 68	/* The Linux interpretation of the CMOS clock register contents:
 69	 * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 70	 * RTC registers show the second which has precisely just started.
 71	 * Let's hope other operating systems interpret the RTC the same way.
 72	 */
 73
 74	/* Since the UIP flag is set for about 2.2 ms and the clock
 75	 * is typically written with a precision of 1 jiffy, trying
 76	 * to obtain a precision better than a few milliseconds is
 77	 * an illusion. Only consistency is interesting, this also
 78	 * allows to use the routine for /dev/rtc without a potential
 79	 * 1 second kernel busy loop triggered by any reader of /dev/rtc.
 80	 */
 81
 82	for (i = 0; i<1000000; i++) {
 83		uip = maple_clock_read(RTC_FREQ_SELECT);
 84		tm->tm_sec = maple_clock_read(RTC_SECONDS);
 85		tm->tm_min = maple_clock_read(RTC_MINUTES);
 86		tm->tm_hour = maple_clock_read(RTC_HOURS);
 87		tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
 88		tm->tm_mon = maple_clock_read(RTC_MONTH);
 89		tm->tm_year = maple_clock_read(RTC_YEAR);
 90		uip |= maple_clock_read(RTC_FREQ_SELECT);
 91		if ((uip & RTC_UIP)==0)
 92			break;
 93	}
 94
 95	if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
 96	    || RTC_ALWAYS_BCD) {
 97		BCD_TO_BIN(tm->tm_sec);
 98		BCD_TO_BIN(tm->tm_min);
 99		BCD_TO_BIN(tm->tm_hour);
100		BCD_TO_BIN(tm->tm_mday);
101		BCD_TO_BIN(tm->tm_mon);
102		BCD_TO_BIN(tm->tm_year);
103	  }
104	if ((tm->tm_year + 1900) < 1970)
105		tm->tm_year += 100;
106
107	GregorianDay(tm);
108}
109
110int maple_set_rtc_time(struct rtc_time *tm)
111{
112	unsigned char save_control, save_freq_select;
113	int sec, min, hour, mon, mday, year;
114
115	spin_lock(&rtc_lock);
116
117	save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
118
119	maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
120
121	save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
122
123	maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
124
125	sec = tm->tm_sec;
126	min = tm->tm_min;
127	hour = tm->tm_hour;
128	mon = tm->tm_mon;
129	mday = tm->tm_mday;
130	year = tm->tm_year;
131
132	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
133		BIN_TO_BCD(sec);
134		BIN_TO_BCD(min);
135		BIN_TO_BCD(hour);
136		BIN_TO_BCD(mon);
137		BIN_TO_BCD(mday);
138		BIN_TO_BCD(year);
139	}
140	maple_clock_write(sec, RTC_SECONDS);
141	maple_clock_write(min, RTC_MINUTES);
142	maple_clock_write(hour, RTC_HOURS);
143	maple_clock_write(mon, RTC_MONTH);
144	maple_clock_write(mday, RTC_DAY_OF_MONTH);
145	maple_clock_write(year, RTC_YEAR);
146
147	/* The following flags have to be released exactly in this order,
148	 * otherwise the DS12887 (popular MC146818A clone with integrated
149	 * battery and quartz) will not reset the oscillator and will not
150	 * update precisely 500 ms later. You won't find this mentioned in
151	 * the Dallas Semiconductor data sheets, but who believes data
152	 * sheets anyway ...                           -- Markus Kuhn
153	 */
154	maple_clock_write(save_control, RTC_CONTROL);
155	maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
156
157	spin_unlock(&rtc_lock);
158
159	return 0;
160}
161
162void __init maple_get_boot_time(struct rtc_time *tm)
163{
164	struct device_node *rtcs;
165
166	rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
167	if (rtcs && rtcs->addrs) {
168		maple_rtc_addr = rtcs->addrs[0].address;
169		printk(KERN_INFO "Maple: Found RTC at 0x%x\n", maple_rtc_addr);
170	} else {
171		maple_rtc_addr = RTC_PORT(0); /* legacy address */
172		printk(KERN_INFO "Maple: No device node for RTC, assuming "
173		       "legacy address (0x%x)\n", maple_rtc_addr);
174	}
175	
176	maple_get_rtc_time(tm);
177}
178
179/* XXX FIXME: Some sane defaults: 125 MHz timebase, 1GHz processor */
180#define DEFAULT_TB_FREQ		125000000UL
181#define DEFAULT_PROC_FREQ	(DEFAULT_TB_FREQ * 8)
182
183void __init maple_calibrate_decr(void)
184{
185	struct device_node *cpu;
186	struct div_result divres;
187	unsigned int *fp = NULL;
188
189	/*
190	 * The cpu node should have a timebase-frequency property
191	 * to tell us the rate at which the decrementer counts.
192	 */
193	cpu = of_find_node_by_type(NULL, "cpu");
194
195	ppc_tb_freq = DEFAULT_TB_FREQ;
196	if (cpu != 0)
197		fp = (unsigned int *)get_property(cpu, "timebase-frequency", NULL);
198	if (fp != NULL)
199		ppc_tb_freq = *fp;
200	else
201		printk(KERN_ERR "WARNING: Estimating decrementer frequency (not found)\n");
202	fp = NULL;
203	ppc_proc_freq = DEFAULT_PROC_FREQ;
204	if (cpu != 0)
205		fp = (unsigned int *)get_property(cpu, "clock-frequency", NULL);
206	if (fp != NULL)
207		ppc_proc_freq = *fp;
208	else
209		printk(KERN_ERR "WARNING: Estimating processor frequency (not found)\n");
210
211	of_node_put(cpu);
212
213	printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
214	       ppc_tb_freq/1000000, ppc_tb_freq%1000000);
215	printk(KERN_INFO "time_init: processor frequency   = %lu.%.6lu MHz\n",
216	       ppc_proc_freq/1000000, ppc_proc_freq%1000000);
217
218	tb_ticks_per_jiffy = ppc_tb_freq / HZ;
219	tb_ticks_per_sec = tb_ticks_per_jiffy * HZ;
220	tb_ticks_per_usec = ppc_tb_freq / 1000000;
221	tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
222	div128_by_32(1024*1024, 0, tb_ticks_per_sec, &divres);
223	tb_to_xs = divres.result_low;
224
225	setup_default_decr();
226}