This patch adds basic constructs in the ARMv8 u-boot code
to handle and apply Cortex-A57 specific erratas.
As and example, the framework showcases how erratas 833069, 826974
and 828024 can be handled and applied.
Later on this framework can be extended to include other
erratas.
Signed-off-by: Bhupesh Sharma <bhupesh.sha...@freescale.com>
---
Changes from v2:
- Addressed comments regarding incorrect handling of bl and ret
sequences.
- Reorganized the code to be more readable.
Changes from v1:
- Addressed Yorks' comments about x29 corruption.
arch/arm/cpu/armv8/start.S | 46 ++++++++++++++++++++++++++++++++++++++++++
arch/arm/include/asm/macro.h | 21 +++++++++++++++++++
2 files changed, 67 insertions(+)
diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 4b11aa4..7cf799a 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -67,6 +67,9 @@ reset:
msr cpacr_el1, x0 /* Enable FP/SIMD */
0:
+ /* Apply ARM core specific erratas */
+ bl apply_core_errata
+
/*
* Cache/BPB/TLB Invalidate
* i-cache is invalidated before enabled in icache_enable()
@@ -97,6 +100,49 @@ master_cpu:
/*-----------------------------------------------------------------------*/
+WEAK(apply_core_errata)
+
+ mov x29, lr /* Save LR */
+ /* For now, we support Cortex-A57 specific errata only */
+
+ /* Check if we are running on a Cortex-A57 core */
+ branch_if_a57_core x0, apply_a57_core_errata
+ b 0f
+
+apply_a57_core_errata:
+
+#ifdef CONFIG_ARM_ERRATA_828024
+ mrs x0, S3_1_c15_c2_0 /* cpuactlr_el1 */
+ /* Disable non-allocate hint of w-b-n-a memory type */
+ mov x0, #0x1 << 49
+ /* Disable write streaming no L1-allocate threshold */
+ mov x0, #0x3 << 25
+ /* Disable write streaming no-allocate threshold */
+ mov x0, #0x3 << 27
+ msr S3_1_c15_c2_0, x0 /* cpuactlr_el1 */
+#endif
+
+#ifdef CONFIG_ARM_ERRATA_826974
+ mrs x0, S3_1_c15_c2_0 /* cpuactlr_el1 */
+ /* Disable speculative load execution ahead of a DMB */
+ mov x0, #0x1 << 59
+ msr S3_1_c15_c2_0, x0 /* cpuactlr_el1 */
+#endif
+
+#ifdef CONFIG_ARM_ERRATA_833069
+ mrs x0, S3_1_c15_c2_0 /* cpuactlr_el1 */
+ /* Disable Enable Invalidates of BTB bit */
+ and x0, x0, #0xE
+ msr S3_1_c15_c2_0, x0 /* cpuactlr_el1 */
+#endif
+0:
+ mov lr, x29 /* Restore LR */
+
+ ret
+ENDPROC(apply_core_errata)
+
+/*-----------------------------------------------------------------------*/
+
WEAK(lowlevel_init)
mov x29, lr /* Save LR */
diff --git a/arch/arm/include/asm/macro.h b/arch/arm/include/asm/macro.h
index 1c8c425..44f883d 100644
--- a/arch/arm/include/asm/macro.h
+++ b/arch/arm/include/asm/macro.h
@@ -74,6 +74,27 @@ lr .req x30
.endm
/*
+ * Branch if current processor is a Cortex-A57 core.
+ */
+.macro branch_if_a57_core, xreg, a57_label
+ mrs \xreg, midr_el1
+ lsr \xreg, \xreg, #4
+ and \xreg, \xreg, #0x00000FFF
+ cmp \xreg, #0xD07 /* Cortex-A57 MPCore processor. */
+ b.eq \a57_label
+.endm
+
+/*
+ * Branch if current processor is a Cortex-A53 core.
+ */
+.macro branch_if_a53_core, xreg, a53_label
+ mrs \xreg, midr_el1
+ lsr \xreg, \xreg, #4
+ cmp \xreg, #0xD03 /* Cortex-A53 MPCore processor. */
+ b.eq \a53_label
+.endm
+
+/*
* Branch if current processor is a slave,
* choose processor with all zero affinity value as the master.
*/
--
1.7.9.5
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