252 lines
6.9 KiB
C
252 lines
6.9 KiB
C
/*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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*
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* Adapted for PowerPC (PReP) by Gary Thomas
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* Modified by Cort Dougan (cort@cs.nmt.edu).
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* Copied and modified from arch/i386/kernel/time.c
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*
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*/
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/timex.h>
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#include <linux/kernel_stat.h>
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#include <linux/mc146818rtc.h>
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#include <linux/init.h>
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#include <linux/bcd.h>
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#include <asm/io.h>
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#include <asm/nvram.h>
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#include <asm/prom.h>
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#include <asm/sections.h>
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#include <asm/time.h>
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extern spinlock_t rtc_lock;
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static int nvram_as1 = NVRAM_AS1;
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static int nvram_as0 = NVRAM_AS0;
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static int nvram_data = NVRAM_DATA;
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long __init chrp_time_init(void)
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{
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struct device_node *rtcs;
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int base;
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rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
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if (rtcs == NULL)
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rtcs = find_compatible_devices("rtc", "ds1385-rtc");
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if (rtcs == NULL || rtcs->addrs == NULL)
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return 0;
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base = rtcs->addrs[0].address;
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nvram_as1 = 0;
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nvram_as0 = base;
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nvram_data = base + 1;
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return 0;
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}
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int chrp_cmos_clock_read(int addr)
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{
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if (nvram_as1 != 0)
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outb(addr>>8, nvram_as1);
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outb(addr, nvram_as0);
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return (inb(nvram_data));
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}
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void chrp_cmos_clock_write(unsigned long val, int addr)
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{
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if (nvram_as1 != 0)
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outb(addr>>8, nvram_as1);
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outb(addr, nvram_as0);
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outb(val, nvram_data);
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return;
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}
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/*
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* Set the hardware clock. -- Cort
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*/
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int chrp_set_rtc_time(unsigned long nowtime)
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{
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unsigned char save_control, save_freq_select;
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struct rtc_time tm;
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spin_lock(&rtc_lock);
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to_tm(nowtime, &tm);
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save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
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chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
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save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
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chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
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tm.tm_year -= 1900;
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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BIN_TO_BCD(tm.tm_sec);
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BIN_TO_BCD(tm.tm_min);
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BIN_TO_BCD(tm.tm_hour);
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BIN_TO_BCD(tm.tm_mon);
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BIN_TO_BCD(tm.tm_mday);
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BIN_TO_BCD(tm.tm_year);
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}
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chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
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chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
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chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
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chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
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chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
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chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
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/* The following flags have to be released exactly in this order,
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* otherwise the DS12887 (popular MC146818A clone with integrated
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* battery and quartz) will not reset the oscillator and will not
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* update precisely 500 ms later. You won't find this mentioned in
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* the Dallas Semiconductor data sheets, but who believes data
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* sheets anyway ... -- Markus Kuhn
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*/
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chrp_cmos_clock_write(save_control, RTC_CONTROL);
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chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
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spin_unlock(&rtc_lock);
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return 0;
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}
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unsigned long chrp_get_rtc_time(void)
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{
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unsigned int year, mon, day, hour, min, sec;
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int uip, i;
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/* The Linux interpretation of the CMOS clock register contents:
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* When the Update-In-Progress (UIP) flag goes from 1 to 0, the
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* RTC registers show the second which has precisely just started.
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* Let's hope other operating systems interpret the RTC the same way.
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*/
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/* Since the UIP flag is set for about 2.2 ms and the clock
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* is typically written with a precision of 1 jiffy, trying
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* to obtain a precision better than a few milliseconds is
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* an illusion. Only consistency is interesting, this also
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* allows to use the routine for /dev/rtc without a potential
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* 1 second kernel busy loop triggered by any reader of /dev/rtc.
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*/
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for ( i = 0; i<1000000; i++) {
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uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
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sec = chrp_cmos_clock_read(RTC_SECONDS);
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min = chrp_cmos_clock_read(RTC_MINUTES);
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hour = chrp_cmos_clock_read(RTC_HOURS);
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day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
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mon = chrp_cmos_clock_read(RTC_MONTH);
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year = chrp_cmos_clock_read(RTC_YEAR);
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uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
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if ((uip & RTC_UIP)==0) break;
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}
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if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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{
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BCD_TO_BIN(sec);
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BCD_TO_BIN(min);
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BCD_TO_BIN(hour);
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BCD_TO_BIN(day);
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BCD_TO_BIN(mon);
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BCD_TO_BIN(year);
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}
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if ((year += 1900) < 1970)
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year += 100;
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return mktime(year, mon, day, hour, min, sec);
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}
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/*
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* Calibrate the decrementer frequency with the VIA timer 1.
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*/
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#define VIA_TIMER_FREQ_6 4700000 /* time 1 frequency * 6 */
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/* VIA registers */
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#define RS 0x200 /* skip between registers */
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#define T1CL (4*RS) /* Timer 1 ctr/latch (low 8 bits) */
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#define T1CH (5*RS) /* Timer 1 counter (high 8 bits) */
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#define T1LL (6*RS) /* Timer 1 latch (low 8 bits) */
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#define T1LH (7*RS) /* Timer 1 latch (high 8 bits) */
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#define ACR (11*RS) /* Auxiliary control register */
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#define IFR (13*RS) /* Interrupt flag register */
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/* Bits in ACR */
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#define T1MODE 0xc0 /* Timer 1 mode */
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#define T1MODE_CONT 0x40 /* continuous interrupts */
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/* Bits in IFR and IER */
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#define T1_INT 0x40 /* Timer 1 interrupt */
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static int __init chrp_via_calibrate_decr(void)
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{
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struct device_node *vias;
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volatile unsigned char __iomem *via;
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int count = VIA_TIMER_FREQ_6 / 100;
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unsigned int dstart, dend;
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vias = find_devices("via-cuda");
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if (vias == 0)
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vias = find_devices("via");
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if (vias == 0 || vias->n_addrs == 0)
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return 0;
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via = ioremap(vias->addrs[0].address, vias->addrs[0].size);
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/* set timer 1 for continuous interrupts */
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out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
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/* set the counter to a small value */
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out_8(&via[T1CH], 2);
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/* set the latch to `count' */
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out_8(&via[T1LL], count);
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out_8(&via[T1LH], count >> 8);
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/* wait until it hits 0 */
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while ((in_8(&via[IFR]) & T1_INT) == 0)
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;
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dstart = get_dec();
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/* clear the interrupt & wait until it hits 0 again */
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in_8(&via[T1CL]);
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while ((in_8(&via[IFR]) & T1_INT) == 0)
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;
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dend = get_dec();
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tb_ticks_per_jiffy = (dstart - dend) / ((6 * HZ)/100);
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tb_to_us = mulhwu_scale_factor(dstart - dend, 60000);
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printk(KERN_INFO "via_calibrate_decr: ticks per jiffy = %u (%u ticks)\n",
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tb_ticks_per_jiffy, dstart - dend);
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iounmap(via);
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return 1;
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}
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void __init chrp_calibrate_decr(void)
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{
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struct device_node *cpu;
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unsigned int freq, *fp;
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if (chrp_via_calibrate_decr())
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return;
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/*
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* The cpu node should have a timebase-frequency property
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* to tell us the rate at which the decrementer counts.
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*/
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freq = 16666000; /* hardcoded default */
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cpu = find_type_devices("cpu");
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if (cpu != 0) {
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fp = (unsigned int *)
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get_property(cpu, "timebase-frequency", NULL);
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if (fp != 0)
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freq = *fp;
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}
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printk("time_init: decrementer frequency = %u.%.6u MHz\n",
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freq/1000000, freq%1000000);
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tb_ticks_per_jiffy = freq / HZ;
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tb_to_us = mulhwu_scale_factor(freq, 1000000);
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}
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