armstub8.S

/*
 * Copyright (c) 2016-2019 Raspberry Pi (Trading) Ltd.
 * Copyright (c) 2016 Stephen Warren <swarren@wwwdotorg.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the copyright holder nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#define BIT(x) (1 << (x))

#if BCM2711
#ifdef HIGH_PERI
#define LOCAL_CONTROL		0x4c0000000
#define LOCAL_PRESCALER		0x4c0000008
#else
#define LOCAL_CONTROL		0xff800000
#define LOCAL_PRESCALER		0xff800008
#endif
#else
#define LOCAL_CONTROL		0x40000000
#define LOCAL_PRESCALER		0x40000008
#endif

#ifdef HIGH_PERI
#define GIC_DISTB		0x4c0041000
#define GIC_CPUB		0x4c0042000
#else
#define GIC_DISTB		0xff841000
#define GIC_CPUB		0xff842000
#endif

#if BCM2711
#define OSC_FREQ		54000000
#else
#define OSC_FREQ		19200000
#endif

#define SCR_RW			BIT(10)
#define SCR_HCE			BIT(8)
#define SCR_SMD			BIT(7)
#define SCR_RES1_5		BIT(5)
#define SCR_RES1_4		BIT(4)
#define SCR_NS			BIT(0)
#define SCR_VAL \
    (SCR_RW | SCR_HCE | SCR_SMD | SCR_RES1_5 | SCR_RES1_4 | SCR_NS)

#define ACTLR_VAL \
	(BIT(0) | BIT(1) | BIT(4) | BIT(5) | BIT(6))

#define CPUECTLR_EL1		S3_1_C15_C2_1
#define CPUECTLR_EL1_SMPEN	BIT(6)

#define SPSR_EL3_D		BIT(9)
#define SPSR_EL3_A		BIT(8)
#define SPSR_EL3_I		BIT(7)
#define SPSR_EL3_F		BIT(6)
#define SPSR_EL3_MODE_EL2H	9
#define SPSR_EL3_VAL \
    (SPSR_EL3_D | SPSR_EL3_A | SPSR_EL3_I | SPSR_EL3_F | SPSR_EL3_MODE_EL2H)

#define L2CTLR_EL1		S3_1_C11_C0_2


#define GICC_CTRLR	0x0
#define GICC_PMR	0x4
#define IT_NR		0x8	// Number of interrupt enable registers (256 total irqs)
#define GICD_CTRLR	0x0
#define GICD_IGROUPR	0x80

.globl _start
_start:
	/*
	 * LOCAL_CONTROL:
	 * Bit 9 clear: Increment by 1 (vs. 2).
	 * Bit 8 clear: Timer source is 19.2MHz crystal (vs. APB).
	 */
	ldr x0, =LOCAL_CONTROL
	str wzr, [x0]
	/* LOCAL_PRESCALER; divide-by (0x80000000 / register_val) == 1 */
	mov w1, 0x80000000
	str w1, [x0, #(LOCAL_PRESCALER - LOCAL_CONTROL)]

	/* Set L2 read/write cache latency to 3 */
	mrs x0, L2CTLR_EL1
	mov x1, #0x22
	orr x0, x0, x1
	msr L2CTLR_EL1, x0

	/* Set up CNTFRQ_EL0 */
	ldr x0, =OSC_FREQ
	msr CNTFRQ_EL0, x0

	/* Set up CNTVOFF_EL2 */
	msr CNTVOFF_EL2, xzr

	/* Enable FP/SIMD */
	/* Bit 10 (TFP) is set to 0 */
	msr CPTR_EL3, xzr

	/* Set up SCR */
	mov x0, #SCR_VAL
	msr SCR_EL3, x0

	/* Set up ACTLR */
	mov x0, #ACTLR_VAL
	msr ACTLR_EL3, x0

	/* Set SMPEN */
	mov x0, #CPUECTLR_EL1_SMPEN
	msr CPUECTLR_EL1, x0

#ifdef GIC
        bl      setup_gic
#endif
	/*
	 * Set up SCTLR_EL2
	 * All set bits below are res1. LE, no WXN/I/SA/C/A/M
	 */
	ldr x0, =0x30c50830
	msr SCTLR_EL2, x0

	/* Switch to EL2 */
	mov x0, #SPSR_EL3_VAL
	msr spsr_el3, x0
	adr x0, in_el2
	msr elr_el3, x0
	eret
in_el2:

	mrs x6, MPIDR_EL1
	and x6, x6, #0x3
	cbz x6, primary_cpu

	adr x5, spin_cpu0
secondary_spin:
	wfe
	ldr x4, [x5, x6, lsl #3]
	cbz x4, secondary_spin
	mov x0, #0
	b boot_kernel

primary_cpu:
	ldr w4, kernel_entry32
	ldr w0, dtb_ptr32

boot_kernel:
	mov x1, #0
	mov x2, #0
	mov x3, #0
	br x4

.ltorg

.org 0xd8
.globl spin_cpu0
spin_cpu0:
	.quad 0
.org 0xe0
.globl spin_cpu1
spin_cpu1:
	.quad 0
.org 0xe8
.globl spin_cpu2
spin_cpu2:
	.quad 0
.org 0xf0
.globl spin_cpu3
spin_cpu3:
	# Shared with next two symbols/.word
	# FW clears the next 8 bytes after reading the initial value, leaving
	# the location suitable for use as spin_cpu3
.org 0xf0
.globl stub_magic
stub_magic:
	.word 0x5afe570b
.org 0xf4
.globl stub_version
stub_version:
	.word 0
.org 0xf8
.globl dtb_ptr32
dtb_ptr32:
	.word 0x0
.org 0xfc
.globl kernel_entry32
kernel_entry32:
	.word 0x0

.org 0x100

#ifdef GIC

setup_gic:				// Called from secure mode - set all interrupts to group 1 and enable.
	mrs	x0, MPIDR_EL1
	ldr	x2, =GIC_DISTB
	tst	x0, #0x3
	b.eq	2f			// primary core

	mov	w0, #3			// Enable group 0 and 1 IRQs from distributor
	str	w0, [x2, #GICD_CTRLR]
2:
	add	x1, x2, #(GIC_CPUB - GIC_DISTB)
	mov	w0, #0x1e7
	str	w0, [x1, #GICC_CTRLR]	// Enable group 1 IRQs from CPU interface
	mov	w0, #0xff
	str	w0, [x1, #GICC_PMR]	// priority mask
	add	x2, x2, #GICD_IGROUPR
	mov	x0, #(IT_NR * 4)
	mov	w1, #~0			// group 1 all the things
3:
	subs	x0, x0, #4
	str	w1, [x2, x0]
	b.ne	3b
	ret

#endif

.globl dtb_space
dtb_space: