From f94e601981410c1b03d0d9706ddbc51a69fd6248 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Wed, 18 Feb 2015 08:04:25 -0600
Subject: [PATCH] Add an IOCTL method to the RTC interface

---
 arch/arm/src/stm32/stm32_rtc_lowerhalf.c |  1 +
 drivers/timers/rtc.c                     | 12 +++++++++++-
 include/nuttx/rtc.h                      | 15 +++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/arm/src/stm32/stm32_rtc_lowerhalf.c b/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
index 1a7c1e27d3..7c4aaf221b 100644
--- a/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
+++ b/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
@@ -118,6 +118,7 @@ static const struct rtc_ops_s g_rtc_ops =
   .rdwkalm    = NULL,
   .setwkalm   = NULL,
 #endif
+  .ioctl      = NULL,
   .destroy    = NULL,
 };
 
diff --git a/drivers/timers/rtc.c b/drivers/timers/rtc.c
index 1d4a0c8278..f3231ded11 100644
--- a/drivers/timers/rtc.c
+++ b/drivers/timers/rtc.c
@@ -502,8 +502,18 @@ static int rtc_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
       break;
 #endif /* CONFIG_RTC_ALARM */
 
+    /* Forward any unrecognized IOCTLs to the lower half driver... they
+     * may represent some architecture-specific command.
+     */
+
     default:
-      ret = -ENOTTY;
+      {
+        ret = -ENOTTY;
+        if (ops->ioctl)
+          {
+            ret = ops->ioctl(upper->lower, cmd, arg);
+          }
+      }
       break;
     }
 
diff --git a/include/nuttx/rtc.h b/include/nuttx/rtc.h
index a84eaf7b89..d9a4e45d7d 100644
--- a/include/nuttx/rtc.h
+++ b/include/nuttx/rtc.h
@@ -261,6 +261,16 @@
 
 #define RTC_WKALM_SET      _RTCIOC(0x0010)
 
+/* Architecture-specific RTC IOCTLS should begin at RTC_USER_IOCBASE.  For
+ * example:
+ *
+ *   #define MY_RTC_IOCTL1 _RTCIOC(RTC_USER_IOCBASE);
+ *   #define MY_RTC_IOCTL2 _RTCIOC(RTC_USER_IOCBASE + 1);
+ *   etc.
+ */
+
+#define RTC_USER_IOCBASE   0x0011
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -406,6 +416,11 @@ struct rtc_ops_s
                        FAR const struct rtc_wkalrm *wkalrm);
 #endif
 
+   /* Support for architecture-specific RTC operations */
+
+  CODE int (*ioctl)(FAR struct rtc_lowerhalf_s *lower, int cmd,
+                    unsigned long arg);
+   
    /* The driver has been unlinked and there are no further open references
     * to the driver.
     */