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Diffstat (limited to 'arch/arc/kernel/head.S')
| -rw-r--r-- | arch/arc/kernel/head.S | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S new file mode 100644 index 000000000..a72bbda2f --- /dev/null +++ b/arch/arc/kernel/head.S @@ -0,0 +1,144 @@ +/* + * ARC CPU startup Code + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * 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. + * + * Vineetg: Dec 2007 + * -Check if we are running on Simulator or on real hardware + * to skip certain things during boot on simulator + */ + +#include <linux/linkage.h> +#include <asm/asm-offsets.h> +#include <asm/entry.h> +#include <asm/arcregs.h> +#include <asm/cache.h> +#include <asm/irqflags.h> + +.macro CPU_EARLY_SETUP + + ; Setting up Vectror Table (in case exception happens in early boot + sr @_int_vec_base_lds, [AUX_INTR_VEC_BASE] + + ; Disable I-cache/D-cache if kernel so configured + lr r5, [ARC_REG_IC_BCR] + breq r5, 0, 1f ; I$ doesn't exist + lr r5, [ARC_REG_IC_CTRL] +#ifdef CONFIG_ARC_HAS_ICACHE + bclr r5, r5, 0 ; 0 - Enable, 1 is Disable +#else + bset r5, r5, 0 ; I$ exists, but is not used +#endif + sr r5, [ARC_REG_IC_CTRL] + +1: + lr r5, [ARC_REG_DC_BCR] + breq r5, 0, 1f ; D$ doesn't exist + lr r5, [ARC_REG_DC_CTRL] + bclr r5, r5, 6 ; Invalidate (discard w/o wback) +#ifdef CONFIG_ARC_HAS_DCACHE + bclr r5, r5, 0 ; Enable (+Inv) +#else + bset r5, r5, 0 ; Disable (+Inv) +#endif + sr r5, [ARC_REG_DC_CTRL] + +1: + +#ifdef CONFIG_ISA_ARCV2 + ; Unaligned access is disabled at reset, so re-enable early as + ; gcc 7.3.1 (ARC GNU 2018.03) onwards generates unaligned access + ; by default + lr r5, [status32] + bset r5, r5, STATUS_AD_BIT + kflag r5 +#endif +.endm + + .section .init.text, "ax",@progbits + +;---------------------------------------------------------------- +; Default Reset Handler (jumped into from Reset vector) +; - Don't clobber r0,r1,r2 as they might have u-boot provided args +; - Platforms can override this weak version if needed +;---------------------------------------------------------------- +WEAK(res_service) + j stext +END(res_service) + +;---------------------------------------------------------------- +; Kernel Entry point +;---------------------------------------------------------------- +ENTRY(stext) + + CPU_EARLY_SETUP + +#ifdef CONFIG_SMP + GET_CPU_ID r5 + cmp r5, 0 + mov.nz r0, r5 + bz .Lmaster_proceed + + ; Non-Masters wait for Master to boot enough and bring them up + ; when they resume, tail-call to entry point + mov blink, @first_lines_of_secondary + j arc_platform_smp_wait_to_boot + +.Lmaster_proceed: +#endif + + ; Clear BSS before updating any globals + ; XXX: use ZOL here + mov r5, __bss_start + sub r6, __bss_stop, r5 + lsr.f lp_count, r6, 2 + lpnz 1f + st.ab 0, [r5, 4] +1: + + ; Uboot - kernel ABI + ; r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2 + ; r1 = magic number (always zero as of now) + ; r2 = pointer to uboot provided cmdline or external DTB in mem + ; These are handled later in handle_uboot_args() + st r0, [@uboot_tag] + st r1, [@uboot_magic] + st r2, [@uboot_arg] + + ; setup "current" tsk and optionally cache it in dedicated r25 + mov r9, @init_task + SET_CURR_TASK_ON_CPU r9, r0 ; r9 = tsk, r0 = scratch + + ; setup stack (fp, sp) + mov fp, 0 + + ; tsk->thread_info is really a PAGE, whose bottom hoists stack + GET_TSK_STACK_BASE r9, sp ; r9 = tsk, sp = stack base(output) + + j start_kernel ; "C" entry point +END(stext) + +#ifdef CONFIG_SMP +;---------------------------------------------------------------- +; First lines of code run by secondary before jumping to 'C' +;---------------------------------------------------------------- + .section .text, "ax",@progbits +ENTRY(first_lines_of_secondary) + + ; setup per-cpu idle task as "current" on this CPU + ld r0, [@secondary_idle_tsk] + SET_CURR_TASK_ON_CPU r0, r1 + + ; setup stack (fp, sp) + mov fp, 0 + + ; set it's stack base to tsk->thread_info bottom + GET_TSK_STACK_BASE r0, sp + + j start_kernel_secondary +END(first_lines_of_secondary) +#endif |