This is a copy of the patch from Pavel to fix some strange behaviour with
data cache, instruction cache and MMU being enabled by u-boot on the
RaspberryPi.
Closes #2774.
---
.../libbsp/arm/shared/include/arm-a9mpcore-start.h | 29 ++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/c/src/lib/libbsp/arm/shared/include/arm-a9mpcore-start.h
b/c/src/lib/libbsp/arm/shared/include/arm-a9mpcore-start.h
index 7d6185b..08a4d7b 100644
--- a/c/src/lib/libbsp/arm/shared/include/arm-a9mpcore-start.h
+++ b/c/src/lib/libbsp/arm/shared/include/arm-a9mpcore-start.h
@@ -129,8 +129,37 @@ BSP_START_TEXT_SECTION static inline void
arm_a9mpcore_start_hook_0(void)
volatile a9mpcore_scu *scu =
(volatile a9mpcore_scu *) BSP_ARM_A9MPCORE_SCU_BASE;
uint32_t cpu_id = arm_cortex_a9_get_multiprocessor_cpu_id();
+ uint32_t sctlr_val;
+ sctlr_val = arm_cp15_get_control();
+
+ /*
+ * Current U-boot loader seems to start kernel image
+ * with I and D caches on and MMU enabled.
+ * If RTEMS application image finds that cache is on
+ * during startup then disable caches.
+ */
+ if (sctlr_val & (ARM_CP15_CTRL_I | ARM_CP15_CTRL_C | ARM_CP15_CTRL_M)) {
+ if (sctlr_val & (ARM_CP15_CTRL_C | ARM_CP15_CTRL_M)) {
+ /*
+ * If the data cache is on then ensure that it is clean
+ * before switching off to be extra carefull.
+ */
+ rtems_cache_flush_entire_data();
+ rtems_cache_invalidate_entire_data();
+ }
+ arm_cp15_flush_prefetch_buffer();
+ sctlr_val &= ~(ARM_CP15_CTRL_I | ARM_CP15_CTRL_C | ARM_CP15_CTRL_M |
ARM_CP15_CTRL_A);
+ arm_cp15_set_control(sctlr_val);
+ }
+ rtems_cache_invalidate_entire_data();
+ rtems_cache_invalidate_entire_instruction();
arm_cp15_branch_predictor_invalidate_all();
+ arm_cp15_tlb_invalidate();
+ arm_cp15_flush_prefetch_buffer();
+
+ /* Clear Translation Table Base Control Register */
+ arm_cp15_set_translation_table_base_control_register(0);
if (cpu_id == 0) {
arm_a9mpcore_start_scu_enable(scu);
--
2.4.6
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