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Diffstat (limited to 'stand/arm/uboot/start.S')
| -rw-r--r-- | stand/arm/uboot/start.S | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/stand/arm/uboot/start.S b/stand/arm/uboot/start.S new file mode 100644 index 0000000..ede6a62 --- /dev/null +++ b/stand/arm/uboot/start.S @@ -0,0 +1,145 @@ +/*- + * Copyright (c) 2008 Semihalf, Rafal Czubak + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <machine/asm.h> +#include <machine/armreg.h> + + .text + .extern _C_LABEL(self_reloc), _C_LABEL(main) + .weak _DYNAMIC + +/* + * Entry point to the loader that U-Boot passes control to. + */ + .globl _start +_start: + +#ifdef _ARM_ARCH_6 + mrc p15, 0, ip, c1, c0, 0 + orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE) + orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE) + mcr p15, 0, ip, c1, c0, 0 +#endif + + /* Save the arguments and return register before calling self_reloc */ + push {r0, r1, r9, lr} + + /* + * Do self-relocation when the weak external symbol _DYNAMIC is non-NULL. + * When linked as a dynamic relocatable file, the linker automatically + * defines _DYNAMIC with a value that is the offset of the dynamic + * relocation info section. + * Note that we're still on u-boot's stack here, but the self_reloc + * code uses only a couple dozen bytes of stack space. + */ + adr ip, .here_off /* .here_off is a symbol whose value */ + ldr r0, [ip] /* is its own offset in the text seg. */ + sub r0, ip, r0 /* Get its pc-relative address and */ + ldr r1, .dynamic_off /* subtract its value and we get */ + teq r1, #0 /* r0 = physaddr we were loaded at. */ + addne r1, r1, r0 /* r1 = dynamic section physaddr. */ + blne _C_LABEL(self_reloc) /* Do reloc if _DYNAMIC is non-NULL. */ + + /* Restore saved arguments */ + pop {r0, r1, r9, lr} + + /* Hint where to look for the API signature */ + ldr ip, =uboot_address + str sp, [ip] + + /* Save U-Boot's r8 and r9 for syscall trampoline */ + ldr ip, =saved_regs + str r8, [ip, #0] /* old gd pointer (use to hold lr) */ + str r9, [ip, #4] /* new gd pointer */ + + /* + * Start loader. Save return address first (r8 is available from + * trampoline save). + */ + mov r8, lr + bl main + mov lr, r8 + + /* Restore U-Boot environment */ + ldr ip, =saved_regs + ldr r8, [ip, #0] + ldr r9, [ip, #4] + mov pc, lr + + /* + * Data for self-relocation, in the text segment for pc-rel access. + */ +.here_off: + .word . +.dynamic_off: + .word _DYNAMIC + +/* + * syscall() + */ +ENTRY(syscall) + /* Save caller's lr, r8 and r9 */ + ldr ip, =saved_regs + str r8, [ip, #8] + str r9, [ip, #12] + str lr, [ip, #16] + /* Restore U-Boot's r8 and r9 */ + ldr r8, [ip, #0] + ldr r9, [ip, #4] + /* Call into U-Boot */ + ldr lr, =return_from_syscall + ldr ip, =syscall_ptr + ldr pc, [ip] +return_from_syscall: + /* Restore loader's r8, r9 and lr */ + ldr ip, =saved_regs + ldr lr, [ip, #16] + ldr r9, [ip, #12] + ldr r8, [ip, #8] + /* Return to caller */ + mov pc, lr + +/* + * Data section + */ + .data + .align 4 + .globl syscall_ptr +syscall_ptr: + .long 0 + + .globl uboot_address +uboot_address: + .long 0 + +saved_regs: + .long 0 /* U-Boot's r8 */ + .long 0 /* U-Boot's r9 */ + .long 0 /* Loader's r8 */ + .long 0 /* Loader's r9 */ + .long 0 /* Loader's lr */ |
