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/*
* boot.S - simple register setup code for stand-alone Linux booting
*
* Copyright (C) 2011 ARM Limited. All rights reserved.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE.txt file.
*/
.syntax unified
.arch_extension sec
.text
.globl _start
_start:
#ifdef SMP
#ifdef VEXPRESS
@
@ Program architected timer frequency
@
mrc p15, 0, r0, c0, c1, 1 @ CPUID_EXT_PFR1
lsr r0, r0, #16
and r0, r0, #1 @ Check generic timer support
beq 1f
ldr r0, =24000000 @ 24MHz timer frequency
mcr p15, 0, r0, c14, c0, 0 @ CNTFRQ
1:
#endif
@
@ CPU initialisation
@
mrc p15, 0, r4, c0, c0, 5 @ MPIDR (ARMv7 only)
and r4, r4, #15 @ CPU number
@
@ Hypervisor / TrustZone initialization
@
@ Set all interrupts to be non-secure
ldr r0, =0x2c001000 @ Dist GIC base
ldr r1, [r0, #0x04] @ Type Register
cmp r4, #0
andeq r1, r1, #0x1f
movne r1, #0
add r2, r0, #0x080 @ Security Register 0
mvn r3, #0
2: str r3, [r2]
sub r1, r1, #1
add r2, r2, #4 @ Next security register
cmp r1, #-1
bne 2b
@ Set GIC priority mask bit [7] = 1
ldr r0, =0x2c002000 @ CPU GIC base
mov r1, #0x80
str r1, [r0, #0x4] @ GIC ICCPMR
@ Set NSACR to allow coprocessor access from non-secure
mrc p15, 0, r0, c1, c1, 2
ldr r1, =0x43fff
orr r0, r0, r1
mcr p15, 0, r0, c1, c1, 2
@ Change to NS-mode
mov r0, #0xf0000000
mcr p15, 0, r0, c12, c0, 1 @ Monitor vector base address
mov r7, #0xffffffff
smc #0 @ Change to NS-mode
@ Check CPU nr again
mrc p15, 0, r0, c0, c0, 5 @ MPIDR (ARMv7 only)
and r0, r0, #15 @ CPU number
cmp r0, #0 @ primary CPU?
beq 2f
@
@ Secondary CPUs (following the RealView SMP booting protocol)
@
ldr r1, =filesystem - 0x100
adr r2, 1f
ldmia r2, {r3 - r7} @ move the code to a location
stmia r1, {r3 - r7} @ less likely to be overridden
#ifdef VEXPRESS
ldr r0, =0x1c010030 @ VE SYS_FLAGS register
#else
ldr r0, =0x10000030 @ RealView SYS_FLAGS register
#endif
mov pc, r1 @ branch to the relocated code
1:
#ifdef VEXPRESS
wfe
#endif
ldr r1, [r0]
cmp r1, #0
beq 1b
mov pc, r1 @ branch to the given address
#endif
2:
@
@ UART initialisation (38400 8N1)
@
#ifdef MACH_MPS
ldr r0, =0x1f005000 @ UART3 base (MPS)
#elif defined (VEXPRESS)
ldr r0, =0x1c090000 @ UART base (Versatile Express)
#else
ldr r0, =0x10009000 @ UART base (RealView/EB)
#endif
mov r1, #0x10 @ ibrd
str r1, [r0, #0x24]
mov r1, #0xc300
orr r1, #0x0001 @ cr
str r1, [r0, #0x30]
@
@ Kernel parameters
@
mov r0, #0
#ifdef MACH_MPS
ldr r1, =10000 @ MPS (temporary)
#elif defined (VEXPRESS)
ldr r1, =2272 @ Versatile Express
#else
ldr r1, =827 @ RealView/EB
#endif
adr r2, atags
mov r3, #0
ldr lr, =kernel
#ifdef THUMB2_KERNEL
orr lr, lr, #1 @ Thumb-2 kernel
#endif
mov pc, lr @ jump to the kernel
.org 0x100
atags:
@ ATAG_CORE
.long 2
.long 0x54410001
@ ATAG_CMDLINE
.long (1f - .) >> 2
.long 0x54410009
/* The kernel boot command line is defined in the Make system */
.asciz KCMD
.align 2
1:
#ifdef USE_INITRD
@ ATAG_INITRD2
.long 4
.long 0x54420005
.long filesystem
.long fs_size
#endif
@ ATAG_NONE
.long 0
.long 0x00000000
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