rtc_class_open
rtc_device = rtc_class_open("rtc0");
EXPORT_SYMBOL_GPL(rtc_class_open);
omap_rtc = rtc_class_open("rtc0");
extern struct rtc_device *rtc_class_open(const char *name);
rtc = rtc_class_open(dev_name(dev));
rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);