101 lines
2.9 KiB
Diff
101 lines
2.9 KiB
Diff
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
|
|
Date: Wed, 24 Sep 2014 22:14:07 +0200
|
|
Subject: [PATCH] ARM: BCM5301X: Disable MMU and Dcache during decompression
|
|
MIME-Version: 1.0
|
|
Content-Type: text/plain; charset=UTF-8
|
|
Content-Transfer-Encoding: 8bit
|
|
|
|
Broadcom devices have broken CFE (bootloader) that leaves hardware in an
|
|
invalid state. It causes problems with booting Linux. On Northstar
|
|
devices kernel was randomly hanging in ~25% of tries during early init.
|
|
Hangs used to happen at random places in the start_kernel. On BCM53573
|
|
kernel doesn't even seem to start booting.
|
|
|
|
To workaround this problem we need to do following very early:
|
|
1) Clear 2 following bits in the SCTLR register:
|
|
#define CR_M (1 << 0) /* MMU enable */
|
|
#define CR_C (1 << 2) /* Dcache enable */
|
|
2) Flush the whole D-cache
|
|
3) Disable L2 cache
|
|
|
|
Unfortunately this patch is not upstreamable as it does above things
|
|
unconditionally. We can't check if we are running on Broadcom platform
|
|
in any safe way and doing such hacks with ARCH_MULTI_V7 is unacceptable
|
|
as it could break other devices support.
|
|
|
|
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
|
|
---
|
|
|
|
--- a/arch/arm/boot/compressed/Makefile
|
|
+++ b/arch/arm/boot/compressed/Makefile
|
|
@@ -31,6 +31,11 @@ ifeq ($(CONFIG_ARCH_ACORN),y)
|
|
OBJS += ll_char_wr.o font.o
|
|
endif
|
|
|
|
+ifeq ($(CONFIG_ARCH_BCM_5301X),y)
|
|
+OBJS += head-bcm_5301x-mpcore.o
|
|
+OBJS += cache-v7-min.o
|
|
+endif
|
|
+
|
|
ifeq ($(CONFIG_ARCH_SA1100),y)
|
|
OBJS += head-sa1100.o
|
|
endif
|
|
--- /dev/null
|
|
+++ b/arch/arm/boot/compressed/head-bcm_5301x-mpcore.S
|
|
@@ -0,0 +1,37 @@
|
|
+/*
|
|
+ *
|
|
+ * Platform specific tweaks. This is merged into head.S by the linker.
|
|
+ *
|
|
+ */
|
|
+
|
|
+#include <linux/linkage.h>
|
|
+#include <asm/assembler.h>
|
|
+#include <asm/cp15.h>
|
|
+
|
|
+ .section ".start", "ax"
|
|
+
|
|
+/*
|
|
+ * This code section is spliced into the head code by the linker
|
|
+ */
|
|
+
|
|
+__plat_uncompress_start:
|
|
+
|
|
+ @ Preserve r8/r7 i.e. kernel entry values
|
|
+ mov r12, r8
|
|
+
|
|
+ @ Clear MMU enable and Dcache enable bits
|
|
+ mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR
|
|
+ bic r0, #CR_C|CR_M
|
|
+ mcr p15, 0, r0, c1, c0, 0 @ Write SCTLR
|
|
+ nop
|
|
+
|
|
+ @ Call the cache invalidation routine
|
|
+ bl v7_flush_dcache_all
|
|
+ nop
|
|
+ mov r0,#0
|
|
+ ldr r3, =0x19022000 @ L2 cache controller, control reg
|
|
+ str r0, [r3, #0x100] @ Disable L2 cache
|
|
+ nop
|
|
+
|
|
+ @ Restore
|
|
+ mov r8, r12
|
|
--- a/arch/arm/boot/compressed/cache-v7-min.S
|
|
+++ b/arch/arm/boot/compressed/cache-v7-min.S
|
|
@@ -12,6 +12,7 @@
|
|
|
|
#include <linux/linkage.h>
|
|
#include <linux/init.h>
|
|
+#include <asm/assembler.h>
|
|
|
|
__INIT
|
|
|
|
@@ -63,7 +64,7 @@ loop2:
|
|
ARM( orr r11, r11, r9, lsl r2 ) @ factor index number into r11
|
|
THUMB( lsl r6, r9, r2 )
|
|
THUMB( orr r11, r11, r6 ) @ factor index number into r11
|
|
- mcr p15, 0, r11, c7, c14, 2 @ clean & invalidate by set/way
|
|
+ mcr p15, 0, r11, c7, c6, 2 @ clean & invalidate by set/way
|
|
subs r9, r9, #1 @ decrement the index
|
|
bge loop2
|
|
subs r4, r4, #1 @ decrement the way
|