1 files changed, 251 insertions, 0 deletions
diff --git a/arch/xtensa/boot/boot-redboot/bootstrap.S b/arch/xtensa/boot/boot-redboot/bootstrap.S
new file mode 100644
index 000000000..bbf3b4b08
--- /dev/null
+++ b/arch/xtensa/boot/boot-redboot/bootstrap.S
@@ -0,0 +1,251 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <variant/core.h>
+#include <asm/regs.h>
+#include <asm/asmmacro.h>
+#include <asm/cacheasm.h>
+	/*
+	 * RB-Data: RedBoot data/bss
+	 * P:	    Boot-Parameters
+	 * L:	    Kernel-Loader
+	 *
+	 * The Linux-Kernel image including the loader must be loaded
+	 * to a position so that the kernel and the boot parameters
+	 * can fit in the space before the load address.
+	 *  ______________________________________________________
+	 * |_RB-Data_|_P_|__________|_L_|___Linux-Kernel___|______|
+	 *                          ^
+	 *                          ^ Load address
+	 *  ______________________________________________________
+	 * |___Linux-Kernel___|_P_|_L_|___________________________|
+	 *
+	 * The loader copies the parameter to the position that will
+	 * be the end of the kernel and itself to the end of the
+	 * parameter list.
+	 */
+
+/* Make sure we have enough space for the 'uncompressor' */
+
+#define STACK_SIZE 32768
+#define HEAP_SIZE (131072*4)
+
+	# a2: Parameter list
+	# a3: Size of parameter list
+
+	.section .start, "ax"
+
+	.globl __start
+	/* this must be the first byte of the loader! */
+__start:
+	entry	sp, 32		# we do not intend to return
+	_call0	_start
+__start_a0:
+	.align 4
+
+	.section .text, "ax"
+	.literal_position
+	.begin literal_prefix .text
+
+	/* put literals in here! */
+
+	.globl _start
+_start:
+
+	/* 'reset' window registers */
+
+	movi	a4, 1
+	wsr	a4, ps
+	rsync
+
+	rsr	a5, windowbase
+	ssl	a5
+	sll	a4, a4
+	wsr	a4, windowstart
+	rsync
+
+	movi	a4, 0x00040000
+	wsr	a4, ps
+	rsync
+
+	/* copy the loader to its address
+	 * Note: The loader itself is a very small piece, so we assume we
+	 *       don't partially overlap. We also assume (even more important)
+	 *	 that the kernel image is out of the way. Usually, when the
+	 *	 load address of this image is not at an arbitrary address,
+	 *	 but aligned to some 10K's we shouldn't overlap.
+	 */
+
+	/* Note: The assembler cannot relax "addi a0, a0, ..." to an
+	   l32r, so we load to a4 first. */
+
+	# addi	a4, a0, __start - __start_a0
+	# mov	a0, a4
+
+	movi	a4, __start
+	movi	a5, __start_a0
+	add	a4, a0, a4
+	sub	a0, a4, a5
+
+	movi	a4, __start
+	movi	a5, __reloc_end
+
+	# a0: address where this code has been loaded
+	# a4: compiled address of __start
+	# a5: compiled end address
+
+	mov.n	a7, a0
+	mov.n	a8, a4
+
+1:
+	l32i	a10, a7, 0
+	l32i	a11, a7, 4
+	s32i	a10, a8, 0
+	s32i	a11, a8, 4
+	l32i	a10, a7, 8
+	l32i	a11, a7, 12
+	s32i	a10, a8, 8
+	s32i	a11, a8, 12
+	addi	a8, a8, 16
+	addi	a7, a7, 16
+	blt	a8, a5, 1b
+
+
+	/* We have to flush and invalidate the caches here before we jump. */
+
+#if XCHAL_DCACHE_IS_WRITEBACK
+
+	___flush_dcache_all a5 a6
+
+#endif
+
+	___invalidate_icache_all a5 a6
+	isync
+
+	movi	a11, _reloc
+	jx	a11
+
+	.globl _reloc
+_reloc:
+
+	/* RedBoot is now at the end of the memory, so we don't have
+	 * to copy the parameter list. Keep the code around; in case
+	 * we need it again. */
+#if 0
+	# a0: load address
+	# a2: start address of parameter list
+	# a3: length of parameter list
+	# a4: __start
+
+	/* copy the parameter list out of the way */
+
+	movi	a6, _param_start
+	add	a3, a2, a3
+2:
+	l32i	a8, a2, 0
+	s32i	a8, a6, 0
+	addi	a2, a2, 4
+	addi	a6, a6, 4
+	blt	a2, a3, 2b
+#endif
+
+	/* clear BSS section */
+	movi	a6, __bss_start
+	movi	a7, __bss_end
+	movi.n	a5, 0
+3:
+	s32i	a5, a6, 0
+	addi	a6, a6, 4
+	blt	a6, a7, 3b
+
+	movi	a5, -16
+	movi	a1, _stack + STACK_SIZE
+	and	a1, a1, a5
+
+	/* Uncompress the kernel */
+
+	# a0: load address
+	# a2: boot parameter
+	# a4: __start
+
+	movi	a3, __image_load
+	sub	a4, a3, a4
+	add	a8, a0, a4
+
+	# a1  Stack
+	# a8(a4)  Load address of the image
+
+	movi	a6, _image_start
+	movi	a10, _image_end
+	movi	a7, 0x1000000
+	sub	a11, a10, a6
+	movi	a9, complen
+	s32i	a11, a9, 0
+
+	movi	a0, 0
+
+	# a6 destination
+	# a7 maximum size of destination
+	# a8 source
+	# a9 ptr to length
+
+	.extern gunzip
+	movi	a4, gunzip
+	beqz	a4, 1f
+
+	callx4	a4
+
+	j	2f
+
+
+	# a6 destination start
+	# a7 maximum size of destination
+	# a8 source start
+	# a9 ptr to length
+	# a10 destination end
+
+1:
+        l32i    a9, a8, 0
+        l32i    a11, a8, 4
+        s32i    a9, a6, 0
+        s32i    a11, a6, 4
+        l32i    a9, a8, 8
+        l32i    a11, a8, 12
+        s32i    a9, a6, 8
+        s32i    a11, a6, 12
+        addi    a6, a6, 16
+        addi    a8, a8, 16
+        blt     a6, a10, 1b
+
+
+	/* jump to the kernel */
+2:
+#if XCHAL_DCACHE_IS_WRITEBACK
+
+	___flush_dcache_all a5 a6
+
+#endif
+
+	___invalidate_icache_all a5 a6
+
+	isync
+
+	# a2  Boot parameter list
+
+	movi	a0, _image_start
+	jx	a0
+
+	.align 16
+	.data
+	.globl avail_ram
+avail_ram:
+	.long	_heap
+	.globl end_avail
+end_avail:
+	.long	_heap + HEAP_SIZE
+
+	.comm _stack, STACK_SIZE
+	.comm _heap, HEAP_SIZE
+
+	.globl end_avail
+	.comm complen, 4
+
+	.end	literal_prefix