mirror of
https://github.com/isometimes/rpi4-osdev
synced 2024-11-09 20:00:40 +00:00
88 lines
1.5 KiB
ArmAsm
88 lines
1.5 KiB
ArmAsm
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#include "boot.h"
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.section ".text.boot"
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.globl _start
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_start:
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ldr x0, =SCTLR_VALUE_MMU_DISABLED
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msr sctlr_el1, x0
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ldr x0, =LOCAL_CONTROL
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str wzr, [x0]
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mov w1, 0x80000000
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str w1, [x0, #(LOCAL_PRESCALER - LOCAL_CONTROL)]
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ldr x0, =OSC_FREQ // Sort out the timer
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msr cntfrq_el0, x0
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msr cntvoff_el2, xzr
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ldr x0, =HCR_VALUE
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msr hcr_el2, x0
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ldr x0, =SCR_VALUE
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msr scr_el3, x0
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ldr x0, =SPSR_VALUE
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msr spsr_el3, x0
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adr x0, in_el2
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msr elr_el3, x0
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eret
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in_el2:
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mrs x6, mpidr_el1
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and x6, x6,#0xFF // Check processor id
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cbz x6, primary_cpu // Hang for all non-primary CPU
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adr x5, spin_cpu0
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proc_hang:
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wfe
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ldr x4, [x5, x6, lsl #3]
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cbz x4, proc_hang
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mov x0, #0
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str x0, [x5, x6, lsl #3] // Zero the address again
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ldr x1, =__test_stack // Get ourselves a fresh stack
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mov sp, x1
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boot_kernel:
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mov x1, #0
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mov x2, #0
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mov x3, #0
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br x4
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b proc_hang
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primary_cpu:
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ldr x1, =__bss_start
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ldr w2, =__bss_size
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memzero:
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cbz w2, startup
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str xzr, [x1], #8
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sub w2, w2, #1
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cbnz w2, memzero
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startup:
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mov sp, #LOW_MEMORY
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bl main
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b proc_hang // should never come here
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.ltorg
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.org 0xd8
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.globl spin_cpu0
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spin_cpu0:
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.quad 0
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.org 0xe0
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.globl spin_cpu1
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spin_cpu1:
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.quad 0
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.org 0xe8
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.globl spin_cpu2
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spin_cpu2:
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.quad 0
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.org 0xf0
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.globl spin_cpu3
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spin_cpu3:
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.quad 0
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