Initial commit

target/linux/ramips/image/lzma-loader/src/head.S

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+/*
+ * LZMA compressed kernel loader for Atheros AR7XXX/AR9XXX based boards
+ *
+ * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * Some parts of this code was based on the OpenWrt specific lzma-loader
+ * for the BCM47xx and ADM5120 based boards:
+ *	Copyright (C) 2004 Manuel Novoa III (mjn3@codepoet.org)
+ *	Copyright (C) 2005 by Oleg I. Vdovikin <oleg@cs.msu.su>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <asm/asm.h>
+#include <asm/regdef.h>
+#include "cp0regdef.h"
+#include "cacheops.h"
+#include "config.h"
+
+#define KSEG0		0x80000000
+
+	.macro	ehb
+	sll     zero, 3
+	.endm
+
+	.text
+
+LEAF(startup)
+	.set noreorder
+	.set mips32
+
+	mtc0	zero, CP0_WATCHLO	# clear watch registers
+	mtc0	zero, CP0_WATCHHI
+	mtc0	zero, CP0_CAUSE		# clear before writing status register
+
+	mfc0	t0, CP0_STATUS
+	li	t1, 0x1000001f
+	or	t0, t1
+	xori	t0, 0x1f
+	mtc0	t0, CP0_STATUS
+	ehb
+
+	mtc0	zero, CP0_COUNT
+	mtc0	zero, CP0_COMPARE
+	ehb
+
+	la	t0, __reloc_label	# get linked address of label
+	bal	__reloc_label		# branch and link to label to
+	nop				# get actual address
+__reloc_label:
+	subu	t0, ra, t0		# get reloc_delta
+
+	beqz	t0, __reloc_done         # if delta is 0 we are in the right place
+	nop
+
+	/* Copy our code to the right place */
+	la	t1, _code_start		# get linked address of _code_start
+	la	t2, _code_end		# get linked address of _code_end
+	addu	t0, t0, t1		# calculate actual address of _code_start
+
+__reloc_copy:
+	lw	t3, 0(t0)
+	sw	t3, 0(t1)
+	add	t1, 4
+	blt	t1, t2, __reloc_copy
+	add	t0, 4
+
+	/* flush cache */
+	la	t0, _code_start
+	la	t1, _code_end
+
+	li	t2, ~(CONFIG_CACHELINE_SIZE - 1)
+	and	t0, t2
+	and	t1, t2
+	li	t2, CONFIG_CACHELINE_SIZE
+
+	b	__flush_check
+	nop
+
+__flush_line:
+	cache	Hit_Writeback_Inv_D, 0(t0)
+	cache	Hit_Invalidate_I, 0(t0)
+	add	t0, t2
+
+__flush_check:
+	bne	t0, t1, __flush_line
+	nop
+
+	sync
+
+__reloc_done:
+
+	/* clear bss */
+	la	t0, _bss_start
+	la	t1, _bss_end
+	b	__bss_check
+	nop
+
+__bss_fill:
+	sw	zero, 0(t0)
+	addi	t0, 4
+
+__bss_check:
+	bne	t0, t1, __bss_fill
+	nop
+
+	/* Setup new "C" stack */
+	la	sp, _stack
+
+	/* reserve stack space for a0-a3 registers */
+	subu	sp, 16
+
+	/* jump to the decompressor routine */
+	la	t0, loader_main
+	jr	t0
+	nop
+
+	.set reorder
+END(startup)