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authorRafał Miłecki <rafal@milecki.pl>2018-12-27 07:58:48 +0100
committerRafał Miłecki <rafal@milecki.pl>2018-12-27 07:59:03 +0100
commit75b134c4c5675898a68ada14f21f997549e2058d (patch)
tree894ada347363b500a96d437a2b29733702f59ee8 /target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch
parent7a7d19abcfc56c5073931e81f481e2e1fdf774c2 (diff)
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bcm53xx: add support for the kernel 4.19
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Diffstat (limited to 'target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch')
-rw-r--r--target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch101
1 files changed, 101 insertions, 0 deletions
diff --git a/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch b/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch
new file mode 100644
index 0000000000..034d5b52fc
--- /dev/null
+++ b/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch
@@ -0,0 +1,101 @@
+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
+@@ -35,6 +35,11 @@ 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