xref: /openbmc/linux/arch/loongarch/kernel/head.S (revision be2b81b5)
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4 */
5#include <linux/init.h>
6#include <linux/threads.h>
7
8#include <asm/addrspace.h>
9#include <asm/asm.h>
10#include <asm/asmmacro.h>
11#include <asm/bug.h>
12#include <asm/regdef.h>
13#include <asm/loongarch.h>
14#include <asm/stackframe.h>
15
16#ifdef CONFIG_EFI_STUB
17
18#include "efi-header.S"
19
20	__HEAD
21
22_head:
23	.word	MZ_MAGIC		/* "MZ", MS-DOS header */
24	.org	0x8
25	.dword	kernel_entry		/* Kernel entry point */
26	.dword	_end - _text		/* Kernel image effective size */
27	.quad	0			/* Kernel image load offset from start of RAM */
28	.org	0x38			/* 0x20 ~ 0x37 reserved */
29	.long	LINUX_PE_MAGIC
30	.long	pe_header - _head	/* Offset to the PE header */
31
32pe_header:
33	__EFI_PE_HEADER
34
35SYM_DATA(kernel_asize, .long _end - _text);
36SYM_DATA(kernel_fsize, .long _edata - _text);
37SYM_DATA(kernel_offset, .long kernel_offset - _text);
38
39#endif
40
41	__REF
42
43	.align 12
44
45SYM_CODE_START(kernel_entry)			# kernel entry point
46
47	/* Config direct window and set PG */
48	li.d		t0, CSR_DMW0_INIT	# UC, PLV0, 0x8000 xxxx xxxx xxxx
49	csrwr		t0, LOONGARCH_CSR_DMWIN0
50	li.d		t0, CSR_DMW1_INIT	# CA, PLV0, 0x9000 xxxx xxxx xxxx
51	csrwr		t0, LOONGARCH_CSR_DMWIN1
52
53	/* We might not get launched at the address the kernel is linked to,
54	   so we jump there.  */
55	la.abs		t0, 0f
56	jr		t0
570:
58	/* Enable PG */
59	li.w		t0, 0xb0		# PLV=0, IE=0, PG=1
60	csrwr		t0, LOONGARCH_CSR_CRMD
61	li.w		t0, 0x04		# PLV=0, PIE=1, PWE=0
62	csrwr		t0, LOONGARCH_CSR_PRMD
63	li.w		t0, 0x00		# FPE=0, SXE=0, ASXE=0, BTE=0
64	csrwr		t0, LOONGARCH_CSR_EUEN
65
66	la.pcrel	t0, __bss_start		# clear .bss
67	st.d		zero, t0, 0
68	la.pcrel	t1, __bss_stop - LONGSIZE
691:
70	addi.d		t0, t0, LONGSIZE
71	st.d		zero, t0, 0
72	bne		t0, t1, 1b
73
74	la.pcrel	t0, fw_arg0
75	st.d		a0, t0, 0		# firmware arguments
76	la.pcrel	t0, fw_arg1
77	st.d		a1, t0, 0
78	la.pcrel	t0, fw_arg2
79	st.d		a2, t0, 0
80
81	/* KSave3 used for percpu base, initialized as 0 */
82	csrwr		zero, PERCPU_BASE_KS
83	/* GPR21 used for percpu base (runtime), initialized as 0 */
84	move		u0, zero
85
86	la.pcrel	tp, init_thread_union
87	/* Set the SP after an empty pt_regs.  */
88	PTR_LI		sp, (_THREAD_SIZE - PT_SIZE)
89	PTR_ADD		sp, sp, tp
90	set_saved_sp	sp, t0, t1
91
92	bl		start_kernel
93	ASM_BUG()
94
95SYM_CODE_END(kernel_entry)
96
97#ifdef CONFIG_SMP
98
99/*
100 * SMP slave cpus entry point.	Board specific code for bootstrap calls this
101 * function after setting up the stack and tp registers.
102 */
103SYM_CODE_START(smpboot_entry)
104	li.d		t0, CSR_DMW0_INIT	# UC, PLV0
105	csrwr		t0, LOONGARCH_CSR_DMWIN0
106	li.d		t0, CSR_DMW1_INIT	# CA, PLV0
107	csrwr		t0, LOONGARCH_CSR_DMWIN1
108
109	la.abs		t0, 0f
110	jr		t0
1110:
112	/* Enable PG */
113	li.w		t0, 0xb0		# PLV=0, IE=0, PG=1
114	csrwr		t0, LOONGARCH_CSR_CRMD
115	li.w		t0, 0x04		# PLV=0, PIE=1, PWE=0
116	csrwr		t0, LOONGARCH_CSR_PRMD
117	li.w		t0, 0x00		# FPE=0, SXE=0, ASXE=0, BTE=0
118	csrwr		t0, LOONGARCH_CSR_EUEN
119
120	la.abs		t0, cpuboot_data
121	ld.d		sp, t0, CPU_BOOT_STACK
122	ld.d		tp, t0, CPU_BOOT_TINFO
123
124	bl		start_secondary
125	ASM_BUG()
126
127SYM_CODE_END(smpboot_entry)
128
129#endif /* CONFIG_SMP */
130
131SYM_ENTRY(kernel_entry_end, SYM_L_GLOBAL, SYM_A_NONE)
132