1/*
  2 *  linux/arch/arm/mm/proc-v7m.S
  3 *
  4 *  Copyright (C) 2008 ARM Ltd.
  5 *  Copyright (C) 2001 Deep Blue Solutions Ltd.
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 *  This is the "shell" of the ARMv7-M processor support.
 12 */
 13#include <linux/linkage.h>
 14#include <asm/assembler.h>
 15#include <asm/v7m.h>
 16#include "proc-macros.S"
 17
 18ENTRY(cpu_v7m_proc_init)
 19	mov	pc, lr
 20ENDPROC(cpu_v7m_proc_init)
 21
 22ENTRY(cpu_v7m_proc_fin)
 23	mov	pc, lr
 24ENDPROC(cpu_v7m_proc_fin)
 25
 26/*
 27 *	cpu_v7m_reset(loc)
 28 *
 29 *	Perform a soft reset of the system.  Put the CPU into the
 30 *	same state as it would be if it had been reset, and branch
 31 *	to what would be the reset vector.
 32 *
 33 *	- loc   - location to jump to for soft reset
 34 */
 35	.align	5
 36ENTRY(cpu_v7m_reset)
 37	mov	pc, r0
 38ENDPROC(cpu_v7m_reset)
 39
 40/*
 41 *	cpu_v7m_do_idle()
 42 *
 43 *	Idle the processor (eg, wait for interrupt).
 44 *
 45 *	IRQs are already disabled.
 46 */
 47ENTRY(cpu_v7m_do_idle)
 48	wfi
 49	mov	pc, lr
 50ENDPROC(cpu_v7m_do_idle)
 51
 52ENTRY(cpu_v7m_dcache_clean_area)
 53	mov	pc, lr
 54ENDPROC(cpu_v7m_dcache_clean_area)
 55
 56/*
 57 * There is no MMU, so here is nothing to do.
 58 */
 59ENTRY(cpu_v7m_switch_mm)
 60	mov	pc, lr
 61ENDPROC(cpu_v7m_switch_mm)
 62
 63.globl	cpu_v7m_suspend_size
 64.equ	cpu_v7m_suspend_size, 0
 65
 66#ifdef CONFIG_ARM_CPU_SUSPEND
 67ENTRY(cpu_v7m_do_suspend)
 68	mov	pc, lr
 69ENDPROC(cpu_v7m_do_suspend)
 70
 71ENTRY(cpu_v7m_do_resume)
 72	mov	pc, lr
 73ENDPROC(cpu_v7m_do_resume)
 74#endif
 75
 76	.section ".text.init", #alloc, #execinstr
 77
 78/*
 79 *	__v7m_setup
 80 *
 81 *	This should be able to cover all ARMv7-M cores.
 82 */
 83__v7m_setup:
 84	@ Configure the vector table base address
 85	ldr	r0, =BASEADDR_V7M_SCB
 86	ldr	r12, =vector_table
 87	str	r12, [r0, V7M_SCB_VTOR]
 88
 89	@ enable UsageFault, BusFault and MemManage fault.
 90	ldr	r5, [r0, #V7M_SCB_SHCSR]
 91	orr	r5, #(V7M_SCB_SHCSR_USGFAULTENA | V7M_SCB_SHCSR_BUSFAULTENA | V7M_SCB_SHCSR_MEMFAULTENA)
 92	str	r5, [r0, #V7M_SCB_SHCSR]
 93
 94	@ Lower the priority of the SVC and PendSV exceptions
 95	mov	r5, #0x80000000
 96	str	r5, [r0, V7M_SCB_SHPR2]	@ set SVC priority
 97	mov	r5, #0x00800000
 98	str	r5, [r0, V7M_SCB_SHPR3]	@ set PendSV priority
 99
100	@ SVC to run the kernel in this mode
101	adr	r1, BSYM(1f)
102	ldr	r5, [r12, #11 * 4]	@ read the SVC vector entry
103	str	r1, [r12, #11 * 4]	@ write the temporary SVC vector entry
104	mov	r6, lr			@ save LR
105	mov	r7, sp			@ save SP
106	ldr	sp, =__v7m_setup_stack_top
107	cpsie	i
108	svc	#0
1091:	cpsid	i
110	str	r5, [r12, #11 * 4]	@ restore the original SVC vector entry
111	mov	lr, r6			@ restore LR
112	mov	sp, r7			@ restore SP
113
114	@ Special-purpose control register
115	mov	r1, #1
116	msr	control, r1		@ Thread mode has unpriviledged access
117
118	@ Configure the System Control Register to ensure 8-byte stack alignment
119	@ Note the STKALIGN bit is either RW or RAO.
120	ldr	r12, [r0, V7M_SCB_CCR]	@ system control register
121	orr	r12, #V7M_SCB_CCR_STKALIGN
122	str	r12, [r0, V7M_SCB_CCR]
123	mov	pc, lr
124ENDPROC(__v7m_setup)
125
126	.align 2
127__v7m_setup_stack:
128	.space	4 * 8				@ 8 registers
129__v7m_setup_stack_top:
130
131	define_processor_functions v7m, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1
132
133	.section ".rodata"
134	string cpu_arch_name, "armv7m"
135	string cpu_elf_name "v7m"
136	string cpu_v7m_name "ARMv7-M"
137
138	.section ".proc.info.init", #alloc, #execinstr
139
140	/*
141	 * Match any ARMv7-M processor core.
142	 */
143	.type	__v7m_proc_info, #object
144__v7m_proc_info:
145	.long	0x000f0000		@ Required ID value
146	.long	0x000f0000		@ Mask for ID
147	.long   0			@ proc_info_list.__cpu_mm_mmu_flags
148	.long   0			@ proc_info_list.__cpu_io_mmu_flags
149	b	__v7m_setup		@ proc_info_list.__cpu_flush
150	.long	cpu_arch_name
151	.long	cpu_elf_name
152	.long	HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT
153	.long	cpu_v7m_name
154	.long	v7m_processor_functions	@ proc_info_list.proc
155	.long	0			@ proc_info_list.tlb
156	.long	0			@ proc_info_list.user
157	.long	nop_cache_fns		@ proc_info_list.cache
158	.size	__v7m_proc_info, . - __v7m_proc_info
159