[SCB] More useful definitions for SHPR fields

The direct access definitions to the SHPR1 SHPR2 and SHPR3 were simply
wrong, and though a handy macro for directly reaching any priority field
was provided, the definitions of the fields assumed direct access to the
registers.

Provide field definitions that match the handy macro, and correct the
direct access definitions for people wishing to use them.

include/libopencm3/cm3/scb.h

@@ -47,9 +47,9 @@
 /* SHP: System Handler Priority Registers */
 /* Note: 12 8bit registers */
 #define SCB_SHPR(shpr_id)			MMIO8(SCB_BASE + 0x18 + shpr_id)
-#define SCB_SHPR1				MMIO8(SCB_BASE + 0x18 + 1)
-#define SCB_SHPR2				MMIO8(SCB_BASE + 0x18 + 2)
-#define SCB_SHPR3				MMIO8(SCB_BASE + 0x18 + 3)
+#define SCB_SHPR1				MMIO32(SCB_BASE + 0x18)
+#define SCB_SHPR2				MMIO32(SCB_BASE + 0x1C)
+#define SCB_SHPR3				MMIO32(SCB_BASE + 0x20)
 
 /* Those defined only on ARMv7 and above */
 #if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
@@ -282,29 +282,22 @@
 #define SCB_CCR_NONBASETHRDENA			(1 << 0)
 #endif
 
-/* --- SCB_SHPR1 values ---------------------------------------------------- */
-
-/* Bits [31:24]: reserved - must be kept cleared */
-/* PRI_6[23:16]: Priority of system handler 6, usage fault */
-#define SCB_SHPR1_PRI_6_LSB			16
-/* PRI_5[15:8]: Priority of system handler 5, bus fault */
-#define SCB_SHPR1_PRI_5_LSB			8
-/* PRI_4[7:0]: Priority of system handler 4, memory management fault */
-#define SCB_SHPR1_PRI_4_LSB			0
-
-/* --- SCB_SHPR2 values ---------------------------------------------------- */
-
-/* PRI_11[31:24]: Priority of system handler 11, SVCall */
-#define SCB_SHPR2_PRI_11_LSB			24
-/* Bits [23:0]: reserved - must be kept cleared */
-
-/* --- SCB_SHPR3 values ---------------------------------------------------- */
-
-/* PRI_15[31:24]: Priority of system handler 15, SysTick exception */
-#define SCB_SHPR3_PRI_15_LSB			24
-/* PRI_14[23:16]: Priority of system handler 14, PendSV */
-#define SCB_SHPR3_PRI_14_LSB			16
-/* Bits [15:0]: reserved - must be kept cleared */
+/* These numbers are designed to be used with the SCB_SHPR() macro */
+/* SCB_SHPR1 */
+#define SCB_SHPR_PRI_4_MEMMANAGE	0
+#define SCB_SHPR_PRI_5_BUSFAULT		1
+#define SCB_SHPR_PRI_6_USAGEFAULT	2
+#define SCB_SHPR_PRI_7_RESERVED		3
+/* SCB_SHPR2  */
+#define SCB_SHPR_PRI_8_RESERVED		4
+#define SCB_SHPR_PRI_9_RESERVED		5
+#define SCB_SHPR_PRI_10_RESERVED	6
+#define SCB_SHPR_PRI_11_SVCALL		7
+/* SCB_SHPR3 */
+#define SCB_SHPR_PRI_12_RESERVED	8
+#define SCB_SHPR_PRI_13_RESERVED	9
+#define SCB_SHPR_PRI_14_PENDSV		10
+#define SCB_SHPR_PRI_15_SYSTICK		11
 
 /* Those defined only on ARMv7 and above */
 #if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)