1/* 2 * ARC CPU startup Code 3 * 4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Vineetg: Dec 2007 11 * -Check if we are running on Simulator or on real hardware 12 * to skip certain things during boot on simulator 13 */ 14 15#include <asm/asm-offsets.h> 16#include <asm/entry.h> 17#include <linux/linkage.h> 18#include <asm/arcregs.h> 19 20 .cpu A7 21 22 .section .init.text, "ax",@progbits 23 .type stext, @function 24 .globl stext 25stext: 26 ;------------------------------------------------------------------- 27 ; Don't clobber r0-r4 yet. It might have bootloader provided info 28 ;------------------------------------------------------------------- 29 30 ; Clear BSS before updating any globals 31 ; XXX: use ZOL here 32 mov r5, __bss_start 33 mov r6, __bss_stop 341: 35 st.ab 0, [r5,4] 36 brlt r5, r6, 1b 37 38#ifdef CONFIG_CMDLINE_UBOOT 39 ; support for bootloader provided cmdline 40 ; If cmdline passed by u-boot, then 41 ; r0 = 1 (because ATAGS parsing, now retired, used to use 0) 42 ; r1 = magic number (board identity) 43 ; r2 = addr of cmdline string (somewhere in memory/flash) 44 45 brne r0, 1, .Lother_bootup_chores ; u-boot didn't pass cmdline 46 breq r2, 0, .Lother_bootup_chores ; or cmdline is NULL 47 48 mov r5, @command_line 491: 50 ldb.ab r6, [r2, 1] 51 breq r6, 0, .Lother_bootup_chores 52 b.d 1b 53 stb.ab r6, [r5, 1] 54#endif 55 56.Lother_bootup_chores: 57 58 ; Identify if running on ISS vs Silicon 59 ; IDENTITY Reg [ 3 2 1 0 ] 60 ; (chip-id) ^^^^^ ==> 0xffff for ISS 61 lr r0, [identity] 62 lsr r3, r0, 16 63 cmp r3, 0xffff 64 mov.z r4, 0 65 mov.nz r4, 1 66 st r4, [@running_on_hw] 67 68 ; setup "current" tsk and optionally cache it in dedicated r25 69 mov r9, @init_task 70 SET_CURR_TASK_ON_CPU r9, r0 ; r9 = tsk, r0 = scratch 71 72 ; setup stack (fp, sp) 73 mov fp, 0 74 75 ; tsk->thread_info is really a PAGE, whose bottom hoists stack 76 GET_TSK_STACK_BASE r9, sp ; r9 = tsk, sp = stack base(output) 77 78 j start_kernel ; "C" entry point 79