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/*
* Support for periodic interrupts (100 per second) and for getting
* the current time from the RTC on Power Macintoshes.
*
* We use the decrementer register for our periodic interrupts.
*
* Paul Mackerras August 1996.
* Copyright (C) 1996 Paul Mackerras.
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <asm/adb.h>
#include <asm/cuda.h>
#include <asm/prom.h>
#include <asm/system.h>
#include "time.h"
/* Apparently the RTC stores seconds since 1 Jan 1904 */
#define RTC_OFFSET 2082844800
/*
* Calibrate the decrementer frequency with the VIA timer 1.
*/
#define VIA_TIMER_FREQ_6 4700000 /* time 1 frequency * 6 */
/* VIA registers */
#define RS 0x200 /* skip between registers */
#define T1CL (4*RS) /* Timer 1 ctr/latch (low 8 bits) */
#define T1CH (5*RS) /* Timer 1 counter (high 8 bits) */
#define T1LL (6*RS) /* Timer 1 latch (low 8 bits) */
#define T1LH (7*RS) /* Timer 1 latch (high 8 bits) */
#define ACR (11*RS) /* Auxiliary control register */
#define IFR (13*RS) /* Interrupt flag register */
/* Bits in ACR */
#define T1MODE 0xc0 /* Timer 1 mode */
#define T1MODE_CONT 0x40 /* continuous interrupts */
/* Bits in IFR and IER */
#define T1_INT 0x40 /* Timer 1 interrupt */
static int via_calibrate_decr(void)
{
struct device_node *vias;
volatile unsigned char *via;
int count = VIA_TIMER_FREQ_6 / HZ;
unsigned int dstart, dend;
vias = find_devices("via-cuda");
if (vias == 0)
vias = find_devices("via-pmu");
if (vias == 0 || vias->n_addrs == 0)
return 0;
via = (volatile unsigned char *) vias->addrs[0].address;
/* set timer 1 for continuous interrupts */
out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
/* set the counter to a small value */
out_8(&via[T1CH], 2);
/* set the latch to `count' */
out_8(&via[T1LL], count);
out_8(&via[T1LH], count >> 8);
/* wait until it hits 0 */
while ((in_8(&via[IFR]) & T1_INT) == 0)
;
dstart = get_dec();
/* clear the interrupt & wait until it hits 0 again */
in_8(&via[T1CL]);
while ((in_8(&via[IFR]) & T1_INT) == 0)
;
dend = get_dec();
decrementer_count = (dstart - dend) / 6;
count_period_num = 60;
count_period_den = decrementer_count * 6 * HZ / 100000;
printk(KERN_INFO "via_calibrate_decr: decrementer_count = %u (%u ticks)\n",
decrementer_count, dstart - dend);
return 1;
}
/*
* Query the OF and get the decr frequency.
* This was taken from the pmac time_init() when merging the prep/pmac
* time functions.
*/
void pmac_calibrate_decr(void)
{
struct device_node *cpu;
int freq, *fp, divisor;
if (via_calibrate_decr())
return;
/*
* The cpu node should have a timebase-frequency property
* to tell us the rate at which the decrementer counts.
*/
cpu = find_type_devices("cpu");
if (cpu == 0)
panic("can't find cpu node in time_init");
fp = (int *) get_property(cpu, "timebase-frequency", NULL);
if (fp == 0)
panic("can't get cpu timebase frequency");
freq = *fp * 60; /* try to make freq/1e6 an integer */
divisor = 60;
printk("time_init: decrementer frequency = %d/%d\n",
freq, divisor);
decrementer_count = freq / HZ / divisor;
count_period_num = divisor;
count_period_den = freq / 1000000;
}
unsigned long
pmac_get_rtc_time(void)
{
struct adb_request req;
/* Get the time from the RTC */
cuda_request(&req, NULL, 2, CUDA_PACKET, CUDA_GET_TIME);
while (!req.complete)
cuda_poll();
if (req.reply_len != 7)
printk(KERN_ERR "pmac_get_rtc_time: got %d byte reply\n",
req.reply_len);
return (req.reply[3] << 24) + (req.reply[4] << 16)
+ (req.reply[5] << 8) + req.reply[6] - RTC_OFFSET;
}
int pmac_set_rtc_time(unsigned long nowtime)
{
return 0;
}
/*
* We can't do this in time_init, because via_cuda_init hasn't
* been called at that stage.
*/
void
pmac_read_rtc_time(void)
{
xtime.tv_sec = pmac_get_rtc_time();
xtime.tv_usec = 0;
last_rtc_update = xtime.tv_sec;
}
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