arm: nxp: mpu: Return constant number of mpu regions
The original implementation of _get_num_regions() parsed the CESR[NRGD]
register field to determine the number of mpu region descriptors
implemented in hardware. There was a possible path in the code to return
zero, which would cause underflow later on in arm_core_mpu_configure().
Coverity complained despite an assert to catch this condition. Instead,
use a preprocessor macro from mcux that defines the number of mpu region
descriptors.
Coverity-CID: 169811
Jira: ZEP-2208
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>
diff --git a/arch/arm/core/cortex_m/mpu/nxp_mpu.c b/arch/arm/core/cortex_m/mpu/nxp_mpu.c
index 05e627d..d9c6076 100644
--- a/arch/arm/core/cortex_m/mpu/nxp_mpu.c
+++ b/arch/arm/core/cortex_m/mpu/nxp_mpu.c
@@ -38,22 +38,7 @@
static inline u8_t _get_num_regions(void)
{
- u32_t type = (SYSMPU->CESR & SYSMPU_CESR_NRGD_MASK)
- >> SYSMPU_CESR_NRGD_SHIFT;
-
- switch (type) {
- case 0:
- return 8;
- case 1:
- return 12;
- case 2:
- return 16;
- default:
- __ASSERT(0, "Unsupported MPU configuration.");
- return 0;
- }
-
- return NXP_MPU_REGION_NUMBER;
+ return FSL_FEATURE_SYSMPU_DESCRIPTOR_COUNT;
}
static void _region_init(u32_t index, u32_t region_base,
