WhyCan Forum(哇酷开发者社区)

#define OSC_32K	32000
#define OSC_ORG	32768
/*
 * This RTC count flow on sun8iw8 platform.
 * 32.768KHz---   --- [32768 count] ---
 *              \/                     \___[seconds reg]
 *              /\                     /
 * 23KHz    ---   --- [32000 count] ---
 *
 * We can calculate how much seconds missing, call sunxi_rtc_fixup.
 */
void sunxi_rtc_fixup(unsigned long *org_time, unsigned long *time)
{
	unsigned long delta;
	unsigned long t1, t2;
	bool out;

	if (!time)
		return;

	if (!org_time) {
		t1 = (unsigned long long)sunxi_rtc_read(SUNXI_GPDATA_REG(6)) << 32;
		t1 |= (unsigned long)sunxi_rtc_read(SUNXI_GPDATA_REG(7));
	} else
		t1 = *org_time;

	t2 = *time;

	out = sunxi_rtc_read(SUNXI_LOSC_CTRL_REG) & RTC_SOURCE_EXTERNAL;

	delta = (t2 > t1) ? (t2 - t1) : (t1 - t2);
	delta = (delta * (OSC_ORG - OSC_32K)) / OSC_ORG;

	if (out)
		*time -= delta;
	else
		*time += delta;
}


void sunxi_rtc_save(unsigned long time, bool force)
{
	unsigned long long tsec = (unsigned long long)time;
	unsigned int save = (0x80000000 & sunxi_rtc_read(SUNXI_GPDATA_REG(6)));

	if (force || !save) {
		sunxi_rtc_write((unsigned int)tsec, SUNXI_GPDATA_REG(7));
		sunxi_rtc_write(((unsigned int)(tsec >> 32) | 0x80000000), SUNXI_GPDATA_REG(6));
	}
}

	/*
	 * If it first time read and have not save it
	 * we should save it to backup register
	 */
	sunxi_rtc_save(time, false);
	rtc_tm_to_time(rtc_tm, &time);
	sunxi_rtc_fixup(NULL, &time);
	rtc_time_to_tm(time, rtc_tm);

	dev_dbg(dev, "Read hardware RTC time %04d-%02d-%02d %02d:%02d:%02d\n",
			rtc_tm->tm_year + 1900, rtc_tm->tm_mon + 1, rtc_tm->tm_mday,
			rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);