diff --git a/include/libopencm3/efm32/common/cmu_common.h b/include/libopencm3/efm32/common/cmu_common.h
index caac95de..e2005946 100644
--- a/include/libopencm3/efm32/common/cmu_common.h
+++ b/include/libopencm3/efm32/common/cmu_common.h
@@ -1,3 +1,5 @@
+/** @addtogroup cmu_defines
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,8 +19,9 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_CMU_H
-#define LIBOPENCM3_EFM32_CMU_H
+#pragma once
+
+/**@{*/
 
 #include <libopencm3/efm32/memorymap.h>
 #include <libopencm3/cm3/common.h>
@@ -701,5 +704,4 @@ void cmu_clock_setup_in_hfxo_out_48mhz(void);
 
 END_DECLS
 
-#endif
-
+/**@}*/
\ No newline at end of file
diff --git a/include/libopencm3/efm32/ezr32wg/cmu.h b/include/libopencm3/efm32/ezr32wg/cmu.h
index f292ab4f..dd293404 100644
--- a/include/libopencm3/efm32/ezr32wg/cmu.h
+++ b/include/libopencm3/efm32/ezr32wg/cmu.h
@@ -1,3 +1,11 @@
+/** @defgroup cmu_defines CMU Defines
+ *
+ * @brief <b>Defined Constants and Types for the EZR32WG Clock Management Unit</b>
+ *
+ * @ingroup EZR32WG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,11 +25,12 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_EZR32WG_CMU_H
-#define LIBOPENCM3_EFM32_EZR32WG_CMU_H
+#pragma once
 
 #include <libopencm3/efm32/common/cmu_common.h>
 
+/**@{*/
+
 /* EZR32WG refers to USART0 as USART0RF
  * because it is connected to the radio MCU.
  */
@@ -29,4 +38,4 @@
 #define CMU_HFPERCLKEN0_USARTRF0 CMU_HFPERCLKEN0_USART0
 #define CMU_USARTRF0             CMU_USART0
 
-#endif
+/**@}*/
\ No newline at end of file
diff --git a/include/libopencm3/efm32/hg/cmu.h b/include/libopencm3/efm32/hg/cmu.h
index 9a9265d3..6d513bf8 100644
--- a/include/libopencm3/efm32/hg/cmu.h
+++ b/include/libopencm3/efm32/hg/cmu.h
@@ -1,3 +1,11 @@
+/** @defgroup cmu_defines CMU Defines
+ *
+ * @brief <b>Defined Constants and Types for the EFM32HG Clock Management Unit</b>
+ *
+ * @ingroup EFM32HG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -18,8 +26,9 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_CMU_H
-#define LIBOPENCM3_EFM32_CMU_H
+/**@{*/
+
+#pragma once
 
 #include <libopencm3/efm32/memorymap.h>
 #include <libopencm3/cm3/common.h>
@@ -673,4 +682,4 @@ void cmu_wait_for_usbclk_selected(enum cmu_osc osc);
 
 END_DECLS
 
-#endif
+/**@}*/
\ No newline at end of file
diff --git a/include/libopencm3/efm32/lg/cmu.h b/include/libopencm3/efm32/lg/cmu.h
index a567a30c..93168705 100644
--- a/include/libopencm3/efm32/lg/cmu.h
+++ b/include/libopencm3/efm32/lg/cmu.h
@@ -1,3 +1,11 @@
+/** @defgroup cmu_defines CMU Defines
+ *
+ * @brief <b>Defined Constants and Types for the EFM32LG Clock Management Unit</b>
+ *
+ * @ingroup EFM32LG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,10 +25,7 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_LG_CMU_H
-#define LIBOPENCM3_EFM32_LG_CMU_H
+#pragma once
 
 #include <libopencm3/efm32/common/cmu_common.h>
 
-#endif
-
diff --git a/include/libopencm3/efm32/wg/cmu.h b/include/libopencm3/efm32/wg/cmu.h
index 17701412..6b6b86c7 100644
--- a/include/libopencm3/efm32/wg/cmu.h
+++ b/include/libopencm3/efm32/wg/cmu.h
@@ -1,3 +1,11 @@
+/** @defgroup cmu_defines CMU Defines
+ *
+ * @brief <b>Defined Constants and Types for the EFM32WG Clock Management Unit</b>
+ *
+ * @ingroup EFM32WG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,9 +25,6 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_WG_CMU_H
-#define LIBOPENCM3_EFM32_WG_CMU_H
+#pragma once
 
 #include <libopencm3/efm32/common/cmu_common.h>
-
-#endif
diff --git a/lib/efm32/common/cmu_common.c b/lib/efm32/common/cmu_common.c
index c1472ed6..8a577516 100644
--- a/lib/efm32/common/cmu_common.c
+++ b/lib/efm32/common/cmu_common.c
@@ -1,3 +1,6 @@
+/** @addtogroup cmu_file CMU peripheral API
+ * @ingroup peripheral_apis
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -20,6 +23,8 @@
 #include <libopencm3/efm32/cmu.h>
 #include <libopencm3/efm32/msc.h>
 
+/**@{*/
+
 /**
  * Enable CMU registers lock.
  */
@@ -270,3 +275,5 @@ void cmu_clock_setup_in_hfxo_out_48mhz(void)
 	/* wait till HFXO not selected */
 	while (cmu_get_hfclk_source() != HFXO);
 }
+
+/**@}*/
\ No newline at end of file
diff --git a/lib/efm32/hg/cmu.c b/lib/efm32/hg/cmu.c
index d5f3b4ce..3d678eeb 100644
--- a/lib/efm32/hg/cmu.c
+++ b/lib/efm32/hg/cmu.c
@@ -1,3 +1,6 @@
+/** @addtogroup cmu_file CMU peripheral API
+ * @ingroup peripheral_apis
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -20,6 +23,8 @@
 
 #include <libopencm3/efm32/cmu.h>
 
+/**@{*/
+
 /**
  * Enable CMU registers lock.
  */
@@ -305,3 +310,5 @@ void cmu_wait_for_usbclk_selected(enum cmu_osc osc)
 		return;
 	}
 }
+
+/**@}*/
\ No newline at end of file