[PATCHv1 007/211] unicore32: new file arch/unicore32/boot/compressed/head.S

["Guan Xuetao" <guanxuetao@mprc.pku.edu.cn>]

From: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>

	entry point before uncompressed in UniCore32 linux-kernel

Signed-off-by: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>
---
 arch/unicore32/boot/compressed/head.S |  203
+++++++++++++++++++++++++++++++++
 1 files changed, 203 insertions(+), 0 deletions(-)

diff --git a/arch/unicore32/boot/compressed/head.S
b/arch/unicore32/boot/compressed/head.S
new file mode 100644
index 0000000..ced47bd
--- /dev/null
+++ b/arch/unicore32/boot/compressed/head.S
@@ -0,0 +1,203 @@
+/*
+ * linux/arch/unicore32/boot/compressed/head.S
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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 <linux/linkage.h>
+
+#define csub	cmpsub
+#define cand	cmpand
+#define nop8	nop; nop; nop; nop; nop; nop; nop; nop
+
+		.section ".start", #alloc, #execinstr
+		.text
+start:
+		.type	start,#function
+
+		/* Initialize ASR, PRIV mode and INTR off */
+		mov	r0, #0xD3
+		mov.a	asr, r0
+
+		adr	r0, LC0
+		ldm	(r1, r2, r3, r5, r6, r7, r8), [r0]+
+		ldw	sp, [r0+], #28
+		sub.a	r0, r0, r1		@ calculate the delta offset
+
+		/*
+		 * if delta is zero, we are running at the address
+		 * we were linked at.
+		 */
+		beq	not_relocated
+
+		/*
+		 * We're running at a different address.  We need to fix
+		 * up various pointers:
+		 *   r5 - zImage base address (_start)
+		 *   r7 - GOT start
+		 *   r8 - GOT end
+		 */
+		add	r5, r5, r0
+		add	r7, r7, r0
+		add	r8, r8, r0
+
+		/*
+		 * we need to fix up pointers into the BSS region.
+		 *   r2 - BSS start
+		 *   r3 - BSS end
+		 *   sp - stack pointer
+		 */
+		add	r2, r2, r0
+		add	r3, r3, r0
+		add	sp, sp, r0
+
+		/*
+		 * Relocate all entries in the GOT table.
+		 * This fixes up the C references.
+		 *   r7 - GOT start
+		 *   r8 - GOT end
+		 */
+1001:		ldw	r1, [r7+], #0
+		add	r1, r1, r0
+		stw.w	r1, [r7]+, #4
+		csub.a	r7, r8
+		bub	1001b
+
+not_relocated:
+		/*
+		 * Clear BSS region.
+		 *   r2 - BSS start
+		 *   r3 - BSS end
+		 */
+		mov	r0, #0
+1002:		stw.w	r0, [r2]+, #4
+		csub.a	r2, r3
+		bub	1002b
+
+		/*
+		 * Turn on the cache.
+		 */
+                mov     r0, #0
+                movc    p0.c5, r0, #28		@ cache invalidate all
+                nop8
+                movc    p0.c6, r0, #6		@ tlb invalidate all
+                nop8
+
+                mov     r0, #0x1c		@ en icache and wb dcache
+                movc    p0.c1, r0, #0
+                nop8
+
+		/*
+		 * Set up some pointers, for starting decompressing.
+		 */
+
+		mov	r1, sp			@ malloc space above stack
+		add	r2, sp, #0x10000	@ 64k max
+
+		/*
+		 * Check to see if we will overwrite ourselves.
+		 *   r4 = final kernel address
+		 *   r5 = start of this image
+		 *   r6 = size of decompressed image
+		 *   r2 = end of malloc space (and therefore this image)
+		 * We basically want:
+		 *   r4 >= r2 -> OK
+		 *   r4 + image length <= r5 -> OK
+		 */
+		ldw	r4, =zreladdr
+		csub.a	r4, r2
+		bea	wont_overwrite
+		add	r0, r4, r6
+		csub.a	r0, r5
+		beb	wont_overwrite
+
+		/*
+		 * If overwrite, just print error message
+		 */
+		b	__error_overwrite
+
+		/*
+		 * We're not in danger of overwriting ourselves.
+		 * Do this the simple way.
+		 */
+wont_overwrite:
+		/*
+		 * decompress_kernel:
+		 *   r0: output_start
+		 *   r1: free_mem_ptr_p
+		 *   r2: free_mem_ptr_end_p
+		 */
+		mov	r0, r4
+		b.l	decompress_kernel	@ C functions
+
+		/*
+		 * Clean and flush the cache to maintain consistency.
+		 */
+		mov	r0, #0
+                movc    p0.c5, r0, #14		@ flush dcache
+		nop8
+                movc    p0.c5, r0, #20		@ icache invalidate all
+                nop8
+
+		/*
+		 * Turn off the Cache and MMU.
+		 */
+		mov	r0, #0			@ disable i/d cache and MMU
+		movc	p0.c1, r0, #0
+                nop8
+
+		mov	r0, #0			@ must be zero
+		ldw	r4, =zreladdr
+		mov	pc, r4			@ call kernel
+
+
+		.align	2
+		.type	LC0, #object
+LC0:		.word	LC0			@ r1
+		.word	__bss_start		@ r2
+		.word	_end			@ r3
+		.word	_start			@ r5
+		.word	_image_size		@ r6
+		.word	_got_start		@ r7
+		.word	_got_end		@ r8
+		.word	decompress_stack_end	@ sp
+		.size	LC0, . - LC0
+
+print_string:
+#ifdef CONFIG_DEBUG_OCD
+2001:		ldb.w	r1, [r0]+, #1
+		csub.a	r1, #0
+		bne	2002f
+		mov	pc, lr
+2002:
+		movc	r2, p1.c0, #0
+		cand.a	r2, #2
+		bne	2002b
+		movc	p1.c1, r1, #1
+		csub.a	r1, #'\n'
+		cmoveq	r1, #'\r'
+		beq	2002b
+		b	2001b
+#else
+		mov	pc, lr
+#endif
+
+__error_overwrite:
+		adr	r0, str_error
+		b.l	print_string
+2001:		nop8
+		b	2001b
+str_error:	.asciz	"\nError: Kernel address OVERWRITE\n"
+		.align
+
+		.ltorg
+
+		.align	4
+		.section ".stack", "aw", %nobits
+decompress_stack:	.space	4096
+decompress_stack_end: