rtas-rtc.c

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#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/ratelimit.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/time.h>


#define MAX_RTC_WAIT 5000   /* 5 sec */
#define RTAS_CLOCK_BUSY (-2)
unsigned long __init rtas_get_boot_time(void)
{
    int ret[8];
    int error;
    unsigned int wait_time;
    u64 max_wait_tb;

    max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
    do {
        error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);

        wait_time = rtas_busy_delay_time(error);
        if (wait_time) {
            /* This is boot time so we spin. */
            udelay(wait_time*1000);
        }
    } while (wait_time && (get_tb() < max_wait_tb));

    if (error != 0) {
        printk_ratelimited(KERN_WARNING
                   "error: reading the clock failed (%d)\n",
                   error);
        return 0;
    }

    return mktime(ret[0], ret[1], ret[2], ret[3], ret[4], ret[5]);
}

/* NOTE: get_rtc_time will get an error if executed in interrupt context
 * and if a delay is needed to read the clock.  In this case we just
 * silently return without updating rtc_tm.
 */
void rtas_get_rtc_time(struct rtc_time *rtc_tm)
{
        int ret[8];
    int error;
    unsigned int wait_time;
    u64 max_wait_tb;

    max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
    do {
        error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);

        wait_time = rtas_busy_delay_time(error);
        if (wait_time) {
            if (in_interrupt()) {
                memset(rtc_tm, 0, sizeof(struct rtc_time));
                printk_ratelimited(KERN_WARNING
                           "error: reading clock "
                           "would delay interrupt\n");
                return; /* delay not allowed */
            }
            msleep(wait_time);
        }
    } while (wait_time && (get_tb() < max_wait_tb));

    if (error != 0) {
        printk_ratelimited(KERN_WARNING
                   "error: reading the clock failed (%d)\n",
                   error);
        return;
        }

    rtc_tm->tm_sec = ret[5];
    rtc_tm->tm_min = ret[4];
    rtc_tm->tm_hour = ret[3];
    rtc_tm->tm_mday = ret[2];
    rtc_tm->tm_mon = ret[1] - 1;
    rtc_tm->tm_year = ret[0] - 1900;
}

int rtas_set_rtc_time(struct rtc_time *tm)
{
    int error, wait_time;
    u64 max_wait_tb;

    max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
    do {
            error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL,
                  tm->tm_year + 1900, tm->tm_mon + 1,
                  tm->tm_mday, tm->tm_hour, tm->tm_min,
                  tm->tm_sec, 0);

        wait_time = rtas_busy_delay_time(error);
        if (wait_time) {
            if (in_interrupt())
                return 1;   /* probably decrementer */
            msleep(wait_time);
        }
    } while (wait_time && (get_tb() < max_wait_tb));

    if (error != 0)
        printk_ratelimited(KERN_WARNING
                   "error: setting the clock failed (%d)\n",
                   error);

        return 0;
}