xref: /openbmc/linux/arch/arm/kernel/head-nommu.S (revision 5bd8e16d) 
1/*
2 *  linux/arch/arm/kernel/head-nommu.S
3 *
4 *  Copyright (C) 1994-2002 Russell King
5 *  Copyright (C) 2003-2006 Hyok S. Choi
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 *  Common kernel startup code (non-paged MM)
12 *
13 */
14#include <linux/linkage.h>
15#include <linux/init.h>
16
17#include <asm/assembler.h>
18#include <asm/ptrace.h>
19#include <asm/asm-offsets.h>
20#include <asm/memory.h>
21#include <asm/cp15.h>
22#include <asm/thread_info.h>
23#include <asm/v7m.h>
24#include <asm/mpu.h>
25#include <asm/page.h>
26
27/*
28 * Kernel startup entry point.
29 * ---------------------------
30 *
31 * This is normally called from the decompressor code.  The requirements
32 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
33 * r1 = machine nr.
34 *
35 * See linux/arch/arm/tools/mach-types for the complete list of machine
36 * numbers for r1.
37 *
38 */
39
40	__HEAD
41
42#ifdef CONFIG_CPU_THUMBONLY
43	.thumb
44ENTRY(stext)
45#else
46	.arm
47ENTRY(stext)
48
49 THUMB(	adr	r9, BSYM(1f)	)	@ Kernel is always entered in ARM.
50 THUMB(	bx	r9		)	@ If this is a Thumb-2 kernel,
51 THUMB(	.thumb			)	@ switch to Thumb now.
52 THUMB(1:			)
53#endif
54
55	setmode	PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
56						@ and irqs disabled
57#if defined(CONFIG_CPU_CP15)
58	mrc	p15, 0, r9, c0, c0		@ get processor id
59#elif defined(CONFIG_CPU_V7M)
60	ldr	r9, =BASEADDR_V7M_SCB
61	ldr	r9, [r9, V7M_SCB_CPUID]
62#else
63	ldr	r9, =CONFIG_PROCESSOR_ID
64#endif
65	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
66	movs	r10, r5				@ invalid processor (r5=0)?
67	beq	__error_p				@ yes, error 'p'
68
69#ifdef CONFIG_ARM_MPU
70	/* Calculate the size of a region covering just the kernel */
71	ldr	r5, =PHYS_OFFSET		@ Region start: PHYS_OFFSET
72	ldr     r6, =(_end)			@ Cover whole kernel
73	sub	r6, r6, r5			@ Minimum size of region to map
74	clz	r6, r6				@ Region size must be 2^N...
75	rsb	r6, r6, #31			@ ...so round up region size
76	lsl	r6, r6, #MPU_RSR_SZ		@ Put size in right field
77	orr	r6, r6, #(1 << MPU_RSR_EN)	@ Set region enabled bit
78	bl	__setup_mpu
79#endif
80	ldr	r13, =__mmap_switched		@ address to jump to after
81						@ initialising sctlr
82	adr	lr, BSYM(1f)			@ return (PIC) address
83 ARM(	add	pc, r10, #PROCINFO_INITFUNC	)
84 THUMB(	add	r12, r10, #PROCINFO_INITFUNC	)
85 THUMB(	mov	pc, r12				)
86 1:	b	__after_proc_init
87ENDPROC(stext)
88
89#ifdef CONFIG_SMP
90	.text
91ENTRY(secondary_startup)
92	/*
93	 * Common entry point for secondary CPUs.
94	 *
95	 * Ensure that we're in SVC mode, and IRQs are disabled.  Lookup
96	 * the processor type - there is no need to check the machine type
97	 * as it has already been validated by the primary processor.
98	 */
99	setmode	PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9
100#ifndef CONFIG_CPU_CP15
101	ldr	r9, =CONFIG_PROCESSOR_ID
102#else
103	mrc	p15, 0, r9, c0, c0		@ get processor id
104#endif
105	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
106	movs	r10, r5				@ invalid processor?
107	beq	__error_p			@ yes, error 'p'
108
109	adr	r4, __secondary_data
110	ldmia	r4, {r7, r12}
111
112#ifdef CONFIG_ARM_MPU
113	/* Use MPU region info supplied by __cpu_up */
114	ldr	r6, [r7]			@ get secondary_data.mpu_szr
115	bl      __setup_mpu			@ Initialize the MPU
116#endif
117
118	adr	lr, BSYM(__after_proc_init)	@ return address
119	mov	r13, r12			@ __secondary_switched address
120 ARM(	add	pc, r10, #PROCINFO_INITFUNC	)
121 THUMB(	add	r12, r10, #PROCINFO_INITFUNC	)
122 THUMB(	mov	pc, r12				)
123ENDPROC(secondary_startup)
124
125ENTRY(__secondary_switched)
126	ldr	sp, [r7, #8]			@ set up the stack pointer
127	mov	fp, #0
128	b	secondary_start_kernel
129ENDPROC(__secondary_switched)
130
131	.type	__secondary_data, %object
132__secondary_data:
133	.long	secondary_data
134	.long	__secondary_switched
135#endif /* CONFIG_SMP */
136
137/*
138 * Set the Control Register and Read the process ID.
139 */
140__after_proc_init:
141#ifdef CONFIG_CPU_CP15
142	/*
143	 * CP15 system control register value returned in r0 from
144	 * the CPU init function.
145	 */
146#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
147	orr	r0, r0, #CR_A
148#else
149	bic	r0, r0, #CR_A
150#endif
151#ifdef CONFIG_CPU_DCACHE_DISABLE
152	bic	r0, r0, #CR_C
153#endif
154#ifdef CONFIG_CPU_BPREDICT_DISABLE
155	bic	r0, r0, #CR_Z
156#endif
157#ifdef CONFIG_CPU_ICACHE_DISABLE
158	bic	r0, r0, #CR_I
159#endif
160#ifdef CONFIG_CPU_HIGH_VECTOR
161	orr	r0, r0, #CR_V
162#else
163	bic	r0, r0, #CR_V
164#endif
165	mcr	p15, 0, r0, c1, c0, 0		@ write control reg
166#endif /* CONFIG_CPU_CP15 */
167	mov	pc, r13
168ENDPROC(__after_proc_init)
169	.ltorg
170
171#ifdef CONFIG_ARM_MPU
172
173
174/* Set which MPU region should be programmed */
175.macro set_region_nr tmp, rgnr
176	mov	\tmp, \rgnr			@ Use static region numbers
177	mcr	p15, 0, \tmp, c6, c2, 0		@ Write RGNR
178.endm
179
180/* Setup a single MPU region, either D or I side (D-side for unified) */
181.macro setup_region bar, acr, sr, side = MPU_DATA_SIDE
182	mcr	p15, 0, \bar, c6, c1, (0 + \side)	@ I/DRBAR
183	mcr	p15, 0, \acr, c6, c1, (4 + \side)	@ I/DRACR
184	mcr	p15, 0, \sr, c6, c1, (2 + \side)		@ I/DRSR
185.endm
186
187/*
188 * Setup the MPU and initial MPU Regions. We create the following regions:
189 * Region 0: Use this for probing the MPU details, so leave disabled.
190 * Region 1: Background region - covers the whole of RAM as strongly ordered
191 * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6
192 * Region 3: Normal, shared, inaccessible from PL0 to protect the vectors page
193 *
194 * r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION
195*/
196
197ENTRY(__setup_mpu)
198
199	/* Probe for v7 PMSA compliance */
200	mrc	p15, 0, r0, c0, c1, 4		@ Read ID_MMFR0
201	and	r0, r0, #(MMFR0_PMSA)		@ PMSA field
202	teq	r0, #(MMFR0_PMSAv7)		@ PMSA v7
203	bne	__error_p			@ Fail: ARM_MPU on NOT v7 PMSA
204
205	/* Determine whether the D/I-side memory map is unified. We set the
206	 * flags here and continue to use them for the rest of this function */
207	mrc	p15, 0, r0, c0, c0, 4		@ MPUIR
208	ands	r5, r0, #MPUIR_DREGION_SZMASK	@ 0 size d region => No MPU
209	beq	__error_p			@ Fail: ARM_MPU and no MPU
210	tst	r0, #MPUIR_nU			@ MPUIR_nU = 0 for unified
211
212	/* Setup second region first to free up r6 */
213	set_region_nr r0, #MPU_RAM_REGION
214	isb
215	/* Full access from PL0, PL1, shared for CONFIG_SMP, cacheable */
216	ldr	r0, =PHYS_OFFSET		@ RAM starts at PHYS_OFFSET
217	ldr	r5,=(MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL)
218
219	setup_region r0, r5, r6, MPU_DATA_SIDE	@ PHYS_OFFSET, shared, enabled
220	beq	1f				@ Memory-map not unified
221	setup_region r0, r5, r6, MPU_INSTR_SIDE @ PHYS_OFFSET, shared, enabled
2221:	isb
223
224	/* First/background region */
225	set_region_nr r0, #MPU_BG_REGION
226	isb
227	/* Execute Never,  strongly ordered, inaccessible to PL0, rw PL1  */
228	mov	r0, #0				@ BG region starts at 0x0
229	ldr	r5,=(MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA)
230	mov	r6, #MPU_RSR_ALL_MEM		@ 4GB region, enabled
231
232	setup_region r0, r5, r6, MPU_DATA_SIDE	@ 0x0, BG region, enabled
233	beq	2f				@ Memory-map not unified
234	setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled
2352:	isb
236
237	/* Vectors region */
238	set_region_nr r0, #MPU_VECTORS_REGION
239	isb
240	/* Shared, inaccessible to PL0, rw PL1 */
241	mov	r0, #CONFIG_VECTORS_BASE	@ Cover from VECTORS_BASE
242	ldr	r5,=(MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL)
243	/* Writing N to bits 5:1 (RSR_SZ) --> region size 2^N+1 */
244	mov	r6, #(((PAGE_SHIFT - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN)
245
246	setup_region r0, r5, r6, MPU_DATA_SIDE	@ VECTORS_BASE, PL0 NA, enabled
247	beq	3f				@ Memory-map not unified
248	setup_region r0, r5, r6, MPU_INSTR_SIDE	@ VECTORS_BASE, PL0 NA, enabled
2493:	isb
250
251	/* Enable the MPU */
252	mrc	p15, 0, r0, c1, c0, 0		@ Read SCTLR
253	bic     r0, r0, #CR_BR			@ Disable the 'default mem-map'
254	orr	r0, r0, #CR_M			@ Set SCTRL.M (MPU on)
255	mcr	p15, 0, r0, c1, c0, 0		@ Enable MPU
256	isb
257	mov pc,lr
258ENDPROC(__setup_mpu)
259#endif
260#include "head-common.S"
261