diff --git a/arch/arm/src/sama5/sam_pck.c b/arch/arm/src/sama5/sam_pck.c
index bdcf9d63665..2f6ddb0b766 100644
--- a/arch/arm/src/sama5/sam_pck.c
+++ b/arch/arm/src/sama5/sam_pck.c
@@ -107,39 +107,49 @@ uint32_t sam_pck_configure(enum pckid_e pckid, enum pckid_clksrc_e clksrc,
   uint32_t clkin;
   uint32_t actual;
 
-  /* Pick a clock source.  Several are possible but only MCK, PLLA, of SCK is
-   * chosen here.
+  /* Pick a clock source.  Several are possible but only MCK, PLLA, the
+   * MAINCK,or SCK are supported here.
    */
 
-  if (clksrc == PCKSRC_SCK)
+   switch (clksrc)
     {
-      /* Pick the slow clock */
+    case PCKSRC_MCK: /* Source clock = MCK or PLLACK */
+      {
+        /* Pick either the MCK or the PLLACK, whichever will best realize
+         * the target frequency.
+         */
 
+        DEBUGASSERT(BOARD_MCK_FREQUENCY < BOARD_PLLA_FREQUENCY);
+
+        /* Pick the PLLACK if it seems like a better choice */
+
+        if (frequency <= BOARD_MCK_FREQUENCY ||
+            frequency < BOARD_PLLA_FREQUENCY / 64)
+          {
+            regval = PMC_PCK_CSS_MCK;
+            clkin  = BOARD_MCK_FREQUENCY;
+          }
+        else
+          {
+            regval = PMC_PCK_CSS_PLLA;
+            clkin  = BOARD_PLLA_FREQUENCY;
+          }
+      }
+      break;
+
+    case PCKSRC_MAINCK: /* Source clock = MAIN clock */
+      regval = PMC_PCK_CSS_MAIN;
+      clkin  = BOARD_MAINCK_FREQUENCY;
+      break;
+
+    case PCKSRC_SCK: /* Source clock = SCK */
       regval = PMC_PCK_CSS_SLOW;
       clkin  = BOARD_SLOWCLK_FREQUENCY;
-    }
+      break;
 
-  /* If the source is not the slow clock, then pick either the MCK or the
-   * PLLACK, whichever will best realize the target frequency.
-   */
-
-  else
-    {
-      DEBUGASSERT(BOARD_MCK_FREQUENCY < BOARD_PLLA_FREQUENCY);
-
-      /* Pick the PLLACK if it seems like a better choice */
-
-      if (frequency <= BOARD_MCK_FREQUENCY ||
-          frequency < BOARD_PLLA_FREQUENCY / 64)
-        {
-          regval = PMC_PCK_CSS_MCK;
-          clkin  = BOARD_MCK_FREQUENCY;
-        }
-      else
-        {
-          regval = PMC_PCK_CSS_PLLA;
-          clkin  = BOARD_PLLA_FREQUENCY;
-        }
+    default:
+      dbg("ERROR: Unknown clock source\n");
+      return 0;
     }
 
   /* The the larger smallest divisor that does not exceed the requested
diff --git a/arch/arm/src/sama5/sam_pck.h b/arch/arm/src/sama5/sam_pck.h
index fb504069661..4e3f2ad8649 100644
--- a/arch/arm/src/sama5/sam_pck.h
+++ b/arch/arm/src/sama5/sam_pck.h
@@ -64,6 +64,7 @@ enum pckid_e
 enum pckid_clksrc_e
 {
   PCKSRC_MCK = 0,  /* Source clock is the master clock (MCK) or PLLA output (PLLACK) */
+  PCKSRC_MAINCK,   /* Source clock is the main clock (probably the XTAL) */
   PCKSRC_SCK       /* Source clock is the slow clock (SCK) */
 };
 
diff --git a/configs/sama5d3-xplained/include/board_384mhz.h b/configs/sama5d3-xplained/include/board_384mhz.h
index 08a26999bcc..eaa3b7db405 100644
--- a/configs/sama5d3-xplained/include/board_384mhz.h
+++ b/configs/sama5d3-xplained/include/board_384mhz.h
@@ -161,6 +161,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (768000000) /* PLLACK:  64 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (384000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (128000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d3-xplained/include/board_396mhz.h b/configs/sama5d3-xplained/include/board_396mhz.h
index ba76c021a0e..638d3a5a237 100644
--- a/configs/sama5d3-xplained/include/board_396mhz.h
+++ b/configs/sama5d3-xplained/include/board_396mhz.h
@@ -119,6 +119,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (792000000) /* PLLACK:  66 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (396000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d3-xplained/include/board_528mhz.h b/configs/sama5d3-xplained/include/board_528mhz.h
index bc726b1c66d..a0942aeedc7 100644
--- a/configs/sama5d3-xplained/include/board_528mhz.h
+++ b/configs/sama5d3-xplained/include/board_528mhz.h
@@ -118,6 +118,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (528000000) /* PLLACK:  44 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (528000000) /* CPU:     PLLACK / 1 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 1 / 1 / 4 */
diff --git a/configs/sama5d3-xplained/include/board_sdram.h b/configs/sama5d3-xplained/include/board_sdram.h
index 4d7a63f261c..5ea28fe0b21 100644
--- a/configs/sama5d3-xplained/include/board_sdram.h
+++ b/configs/sama5d3-xplained/include/board_sdram.h
@@ -57,6 +57,7 @@
  * the Main clock source in the on-board 12MHz crystal.
  */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (sam_pllack_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PLLADIV2_FREQUENCY   (sam_plladiv2_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PCK_FREQUENCY        (sam_pck_frequency(BOARD_MAINOSC_FREQUENCY))
diff --git a/configs/sama5d3x-ek/include/board_384mhz.h b/configs/sama5d3x-ek/include/board_384mhz.h
index 057746fc1c4..158cd44c8b2 100644
--- a/configs/sama5d3x-ek/include/board_384mhz.h
+++ b/configs/sama5d3x-ek/include/board_384mhz.h
@@ -161,6 +161,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (768000000) /* PLLACK:  64 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (384000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (128000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d3x-ek/include/board_396mhz.h b/configs/sama5d3x-ek/include/board_396mhz.h
index f8e5309a5da..dea0068b0c5 100644
--- a/configs/sama5d3x-ek/include/board_396mhz.h
+++ b/configs/sama5d3x-ek/include/board_396mhz.h
@@ -119,6 +119,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (792000000) /* PLLACK:  66 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (396000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d3x-ek/include/board_528mhz.h b/configs/sama5d3x-ek/include/board_528mhz.h
index 27b69c0d29f..e3975deebe3 100644
--- a/configs/sama5d3x-ek/include/board_528mhz.h
+++ b/configs/sama5d3x-ek/include/board_528mhz.h
@@ -118,6 +118,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (528000000) /* PLLACK:  44 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (528000000) /* CPU:     PLLACK / 1 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 1 / 1 / 4 */
diff --git a/configs/sama5d3x-ek/include/board_sdram.h b/configs/sama5d3x-ek/include/board_sdram.h
index 019005680f0..f6bdbb46d0c 100644
--- a/configs/sama5d3x-ek/include/board_sdram.h
+++ b/configs/sama5d3x-ek/include/board_sdram.h
@@ -57,6 +57,7 @@
  * the Main clock source in the on-board 12MHz crystal.
  */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (sam_pllack_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PLLADIV2_FREQUENCY   (sam_plladiv2_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PCK_FREQUENCY        (sam_pck_frequency(BOARD_MAINOSC_FREQUENCY))
diff --git a/configs/sama5d4-ek/include/board_384mhz.h b/configs/sama5d4-ek/include/board_384mhz.h
index d1797e393b9..d38fa28a246 100644
--- a/configs/sama5d4-ek/include/board_384mhz.h
+++ b/configs/sama5d4-ek/include/board_384mhz.h
@@ -159,6 +159,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (768000000) /* PLLACK:  64 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (384000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (128000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d4-ek/include/board_396mhz.h b/configs/sama5d4-ek/include/board_396mhz.h
index 58895ae3288..9e92ce07a9c 100644
--- a/configs/sama5d4-ek/include/board_396mhz.h
+++ b/configs/sama5d4-ek/include/board_396mhz.h
@@ -117,6 +117,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (792000000) /* PLLACK:  66 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (396000000) /* CPU:     PLLACK / 2 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 2 / 1 / 3 */
diff --git a/configs/sama5d4-ek/include/board_528mhz.h b/configs/sama5d4-ek/include/board_528mhz.h
index 31b05e36e9e..d23cce539c8 100644
--- a/configs/sama5d4-ek/include/board_528mhz.h
+++ b/configs/sama5d4-ek/include/board_528mhz.h
@@ -116,6 +116,7 @@
 
 /* Resulting frequencies */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (528000000) /* PLLACK:  44 * 12Mhz / 1 */
 #define BOARD_PCK_FREQUENCY        (528000000) /* CPU:     PLLACK / 1 / 1  */
 #define BOARD_MCK_FREQUENCY        (132000000) /* MCK:     PLLACK / 1 / 1 / 4 */
diff --git a/configs/sama5d4-ek/include/board_sdram.h b/configs/sama5d4-ek/include/board_sdram.h
index 535bc919614..00c91c0defa 100644
--- a/configs/sama5d4-ek/include/board_sdram.h
+++ b/configs/sama5d4-ek/include/board_sdram.h
@@ -57,6 +57,7 @@
  * the Main clock source in the on-board 12MHz crystal.
  */
 
+#define BOARD_MAINCK_FREQUENCY     BOARD_MAINOSC_FREQUENCY
 #define BOARD_PLLA_FREQUENCY       (sam_pllack_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PLLADIV2_FREQUENCY   (sam_plladiv2_frequency(BOARD_MAINOSC_FREQUENCY))
 #define BOARD_PCK_FREQUENCY        (sam_pck_frequency(BOARD_MAINOSC_FREQUENCY))