diff options
Diffstat (limited to 'arch/xtensa/boot/boot-redboot/bootstrap.S')
| -rw-r--r-- | arch/xtensa/boot/boot-redboot/bootstrap.S | 251 |
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..48ba5a232 --- /dev/null +++ b/arch/xtensa/boot/boot-redboot/bootstrap.S @@ -0,0 +1,251 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <asm/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 |