+Note that many of these ioctls need not actually be implemented by your
+driver. The common rtc-dev interface handles many of these nicely if your
+driver returns ENOIOCTLCMD. Some common examples:
+
+ * RTC_RD_TIME, RTC_SET_TIME: the read_time/set_time functions will be
+ called with appropriate values.
+
+ * RTC_ALM_SET, RTC_ALM_READ, RTC_WKALM_SET, RTC_WKALM_RD: the
+ set_alarm/read_alarm functions will be called.
+
+ * RTC_IRQP_SET, RTC_IRQP_READ: the irq_set_freq function will be called
+ to set the frequency while the framework will handle the read for you
+ since the frequency is stored in the irq_freq member of the rtc_device
+ structure. Your driver needs to initialize the irq_freq member during
+ init. Make sure you check the requested frequency is in range of your
+ hardware in the irq_set_freq function. If it isn't, return -EINVAL. If
+ you cannot actually change the frequency, do not define irq_set_freq.
+
+ * RTC_PIE_ON, RTC_PIE_OFF: the irq_set_state function will be called.
+
+If all else fails, check out the rtc-test.c driver!
+