gem5/system/arm/aarch64_bootloader/boot.S
ARM gem5 Developers 612f8f074f arm: Add support for ARMv8 (AArch64 & AArch32)
Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.

Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.

Contributors:
Giacomo Gabrielli    (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt       (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole           (AArch64 NEON, validation)
Ali Saidi            (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang         (AArch64 Linux support)
Rene De Jong         (AArch64 Linux support, performance opt.)
Matt Horsnell        (AArch64 MP, validation)
Matt Evans           (device models, code integration, validation)
Chris Adeniyi-Jones  (AArch64 syscall-emulation)
Prakash Ramrakhyani  (validation)
Dam Sunwoo           (validation)
Chander Sudanthi     (validation)
Stephan Diestelhorst (validation)
Andreas Hansson      (code integration, performance opt.)
Eric Van Hensbergen  (performance opt.)
Gabe Black
2014-01-24 15:29:34 -06:00

124 lines
3 KiB
ArmAsm

/*
* boot.S - simple register setup code for stand-alone Linux booting
*
* Copyright (C) 2012 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.
*/
.text
.globl _start
_start:
/*
* EL3 initialisation
*/
mrs x0, CurrentEL
cmp x0, #0xc // EL3?
b.ne start_ns // skip EL3 initialisation
mov x0, #0x30 // RES1
orr x0, x0, #(1 << 0) // Non-secure EL1
orr x0, x0, #(1 << 8) // HVC enable
orr x0, x0, #(1 << 10) // 64-bit EL2
msr scr_el3, x0
msr cptr_el3, xzr // Disable copro. traps to EL3
ldr x0, =CNTFRQ
msr cntfrq_el0, x0
/*
* Check for the primary CPU to avoid a race on the distributor
* registers.
*/
mrs x0, mpidr_el1
tst x0, #15
b.ne 1f // secondary CPU
ldr x1, =GIC_DIST_BASE // GICD_CTLR
mov w0, #3 // EnableGrp0 | EnableGrp1
str w0, [x1]
1: ldr x1, =GIC_DIST_BASE + 0x80 // GICD_IGROUPR
mov w0, #~0 // Grp1 interrupts
str w0, [x1], #4
b.ne 2f // Only local interrupts for secondary CPUs
str w0, [x1], #4
str w0, [x1], #4
2: ldr x1, =GIC_CPU_BASE // GICC_CTLR
ldr w0, [x1]
mov w0, #3 // EnableGrp0 | EnableGrp1
str w0, [x1]
mov w0, #1 << 7 // allow NS access to GICC_PMR
str w0, [x1, #4] // GICC_PMR
msr sctlr_el2, xzr
/*
* Prepare the switch to the EL2_SP1 mode from EL3
*/
ldr x0, =start_ns // Return after mode switch
mov x1, #0x3c9 // EL2_SP1 | D | A | I | F
msr elr_el3, x0
msr spsr_el3, x1
eret
start_ns:
/*
* Kernel parameters
*/
mov x0, xzr
mov x1, xzr
mov x2, xzr
mov x3, xzr
mrs x4, mpidr_el1
tst x4, #15
b.eq 2f
/*
* Secondary CPUs
*/
1: wfe
ldr x4, =PHYS_OFFSET + 0xfff8
ldr x4, [x4]
cbz x4, 1b
br x4 // branch to the given address
2:
/*
* UART initialisation (38400 8N1)
*/
ldr x4, =UART_BASE // UART base
mov w5, #0x10 // ibrd
str w5, [x4, #0x24]
mov w5, #0xc300
orr w5, w5, #0x0001 // cr
str w5, [x4, #0x30]
/*
* CLCD output site MB
*/
ldr x4, =SYSREGS_BASE
ldr w5, =(1 << 31) | (1 << 30) | (7 << 20) | (0 << 16) // START|WRITE|MUXFPGA|SITE_MB
str wzr, [x4, #0xa0] // V2M_SYS_CFGDATA
str w5, [x4, #0xa4] // V2M_SYS_CFGCTRL
// set up the arch timer frequency
//ldr x0, =CNTFRQ
//msr cntfrq_el0, x0
/*
* Primary CPU
*/
ldr x0, =PHYS_OFFSET + 0x8000000 // device tree blob
ldr x6, =PHYS_OFFSET + 0x80000 // kernel start address
br x6
.ltorg
.org 0x200