openwrt/target/linux/bcm53xx/patches-3.14/300-ARM-BCM5301X-Disable-MMU-and-Dcache-for-decompression.patch

From 26023cdfacaf116545b1087b9d1fe50dc6fbda10 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
Date: Wed, 24 Sep 2014 22:14:07 +0200
Subject: [PATCH] ARM: BCM5301X: Disable MMU and Dcache for decompression
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Without this fix kernel was randomly hanging in ~25% of tries during
early init. Hangs used to happen at random places in the start_kernel.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
---
 arch/arm/boot/compressed/Makefile                |   5 +
 arch/arm/boot/compressed/head-bcm_5301x-mpcore.S |  37 +++++++
 arch/arm/boot/compressed/mpcore_cache.S          | 118 +++++++++++++++++++++++
 3 files changed, 160 insertions(+)
 create mode 100644 arch/arm/boot/compressed/head-bcm_5301x-mpcore.S
 create mode 100644 arch/arm/boot/compressed/mpcore_cache.S

--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -44,6 +44,11 @@ ifeq ($(CONFIG_ARCH_ACORN),y)
 OBJS		+= ll_char_wr.o font.o
 endif
 
+ifeq ($(CONFIG_ARCH_BCM_5301X),y)
+OBJS		+= head-bcm_5301x-mpcore.o
+OBJS		+= mpcore_cache.o
+endif
+
 ifeq ($(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_all_dcache_invalidate
+	nop
+	mov	r0,#0
+	ldr	r3, =0x19022000			@ L2 cache controller, control reg
+	str	r0, [r3, #0x100]		@ Disable L2 cache
+	nop
+
+	@ Restore
+	mov	r8, r12
--- /dev/null
+++ b/arch/arm/boot/compressed/mpcore_cache.S
@@ -0,0 +1,118 @@
+/*****************************************************************************
+* Copyright 2003 - 2008 Broadcom Corporation. All rights reserved.
+*
+* Unless you and Broadcom execute a separate written software license
+* agreement governing use of this software, this software is licensed to you
+* under the terms of the GNU General Public License version 2, available at
+* http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
+*
+* Notwithstanding the above, under no circumstances may you combine this
+* software in any way with any other Broadcom software provided under a
+* license other than the GPL, without Broadcom's express prior written
+* consent.
+*****************************************************************************/
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+	__INIT
+
+/*
+ * v7_l1_cache_invalidate
+ *
+ * Invalidate contents of L1 cache without flushing its contents
+ * into outer cache and memory. This is needed when the contents
+ * of the cache are unpredictable after power-up.
+ *
+ * corrupts r0-r6
+ */
+
+ENTRY(v7_l1_cache_invalidate)
+	mov	r0, #0
+	mcr	p15, 2, r0, c0, c0, 0	@ set cache level to 1
+	mrc	p15, 1, r0, c0, c0, 0	@ read CLIDR
+
+	ldr	r1, =0x7fff
+	and	r2, r1, r0, lsr #13	@ get max # of index size
+
+	ldr	r1, =0x3ff
+	and	r3, r1, r0, lsr #3	@ NumWays - 1
+	add	r2, r2, #1		@ NumSets
+
+	and	r0, r0, #0x7
+	add	r0, r0, #4		@ SetShift
+
+	clz	r1, r3			@ WayShift
+	add	r4, r3, #1		@ NumWays
+1:	sub	r2, r2, #1		@ NumSets--
+	mov	r3, r4			@ Temp = NumWays
+2:	subs	r3, r3, #1		@ Temp--
+	mov	r5, r3, lsl r1
+	mov	r6, r2, lsl r0
+	orr	r5, r5, r6		@ Reg = (Temp<<WayShift)|(NumSets<<SetShift)
+	mcr	p15, 0, r5, c7, c6, 2	@ Invalidate line
+	bgt	2b
+	cmp	r2, #0
+	bgt	1b
+	dsb
+	mov	r0,#0
+	mcr	p15,0,r0,c7,c5,0	/* Invalidate icache */
+	isb
+	mov	pc, lr
+ENDPROC(v7_l1_cache_invalidate)
+
+/*
+ * v7_all_dcache_invalidate
+ *
+ * Invalidate without flushing the contents of all cache levels
+ * accesible by the current processor core.
+ * This is useful when the contents of cache memory are undetermined
+ * at power-up.
+ *	Corrupted registers: r0-r7, r9-r11
+ *
+ * Based on cache-v7.S: v7_flush_dcache_all()
+ */
+
+ENTRY(v7_all_dcache_invalidate)
+	mrc	p15, 1, r0, c0, c0, 1	@ read clidr
+	ands	r3, r0, #0x7000000	@ extract loc from clidr
+	mov	r3, r3, lsr #23		@ left align loc bit field
+	beq	finished		@ if loc is 0, then no need to clean
+	mov	r10, #0			@ start clean at cache level 0
+loop1:
+	add	r2, r10, r10, lsr #1	@ work out 3x current cache level
+	mov	r1, r0, lsr r2		@ extract cache type bits from clidr
+	and	r1, r1, #7		@ mask of bits for current cache only
+	cmp	r1, #2			@ see what cache we have at this level
+	blt	skip			@ skip if no cache, or just i-cache
+	mcr	p15, 2, r10, c0, c0, 0	@ select current cache level in cssr
+	isb				@ isb to sych the new cssr&csidr
+	mrc	p15, 1, r1, c0, c0, 0	@ read the new csidr
+	and	r2, r1, #7		@ extract the length of the cache lines
+	add	r2, r2, #4		@ add 4 (line length offset)
+	ldr	r4, =0x3ff
+	ands	r4, r4, r1, lsr #3	@ find maximum number on the way size
+	clz	r5, r4			@ find bit pos of way size increment
+	ldr	r7, =0x7fff
+	ands	r7, r7, r1, lsr #13	@ extract max number of the index size
+loop2:
+	mov	r9, r4			@ create working copy of max way size
+loop3:
+	orr	r11, r10, r9, lsl r5	@ factor way and cache number into r11
+	orr	r11, r11, r7, lsl r2	@ factor index number into r11
+	mcr	p15, 0, r11, c7, c6, 2	@ Invalidate line
+	subs	r9, r9, #1		@ decrement the way
+	bge	loop3
+	subs	r7, r7, #1		@ decrement the index
+	bge	loop2
+skip:
+	add	r10, r10, #2		@ increment cache number
+	cmp	r3, r10
+	bgt	loop1
+finished:
+	mov	r10, #0			@ swith back to cache level 0
+	mcr	p15, 2, r10, c0, c0, 0	@ select current cache level in cssr
+	dsb
+	isb
+	mov	pc, lr
+ENDPROC(v7_all_dcache_invalidate)