xref: /openbmc/linux/arch/arm/kernel/head-nommu.S (revision 15b7cc78) 
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(	badr	r9, 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, =PLAT_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
81	badr	lr, 1f				@ return (PIC) address
82	ldr	r12, [r10, #PROCINFO_INITFUNC]
83	add	r12, r12, r10
84	ret	r12
851:	bl	__after_proc_init
86	b	__mmap_switched
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	ldr	r7, __secondary_data
110
111#ifdef CONFIG_ARM_MPU
112	/* Use MPU region info supplied by __cpu_up */
113	ldr	r6, [r7]			@ get secondary_data.mpu_szr
114	bl      __setup_mpu			@ Initialize the MPU
115#endif
116
117	badr	lr, 1f				@ return (PIC) address
118	ldr	r12, [r10, #PROCINFO_INITFUNC]
119	add	r12, r12, r10
120	ret	r12
1211:	bl	__after_proc_init
122	ldr	sp, [r7, #12]			@ set up the stack pointer
123	mov	fp, #0
124	b	secondary_start_kernel
125ENDPROC(secondary_startup)
126
127	.type	__secondary_data, %object
128__secondary_data:
129	.long	secondary_data
130#endif /* CONFIG_SMP */
131
132/*
133 * Set the Control Register and Read the process ID.
134 */
135__after_proc_init:
136#ifdef CONFIG_CPU_CP15
137	/*
138	 * CP15 system control register value returned in r0 from
139	 * the CPU init function.
140	 */
141#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
142	orr	r0, r0, #CR_A
143#else
144	bic	r0, r0, #CR_A
145#endif
146#ifdef CONFIG_CPU_DCACHE_DISABLE
147	bic	r0, r0, #CR_C
148#endif
149#ifdef CONFIG_CPU_BPREDICT_DISABLE
150	bic	r0, r0, #CR_Z
151#endif
152#ifdef CONFIG_CPU_ICACHE_DISABLE
153	bic	r0, r0, #CR_I
154#endif
155#ifdef CONFIG_CPU_HIGH_VECTOR
156	orr	r0, r0, #CR_V
157#else
158	bic	r0, r0, #CR_V
159#endif
160	mcr	p15, 0, r0, c1, c0, 0		@ write control reg
161#endif /* CONFIG_CPU_CP15 */
162	ret	lr
163ENDPROC(__after_proc_init)
164	.ltorg
165
166#ifdef CONFIG_ARM_MPU
167
168
169/* Set which MPU region should be programmed */
170.macro set_region_nr tmp, rgnr
171	mov	\tmp, \rgnr			@ Use static region numbers
172	mcr	p15, 0, \tmp, c6, c2, 0		@ Write RGNR
173.endm
174
175/* Setup a single MPU region, either D or I side (D-side for unified) */
176.macro setup_region bar, acr, sr, side = MPU_DATA_SIDE
177	mcr	p15, 0, \bar, c6, c1, (0 + \side)	@ I/DRBAR
178	mcr	p15, 0, \acr, c6, c1, (4 + \side)	@ I/DRACR
179	mcr	p15, 0, \sr, c6, c1, (2 + \side)		@ I/DRSR
180.endm
181
182/*
183 * Setup the MPU and initial MPU Regions. We create the following regions:
184 * Region 0: Use this for probing the MPU details, so leave disabled.
185 * Region 1: Background region - covers the whole of RAM as strongly ordered
186 * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6
187 * Region 3: Normal, shared, inaccessible from PL0 to protect the vectors page
188 *
189 * r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION
190*/
191
192ENTRY(__setup_mpu)
193
194	/* Probe for v7 PMSA compliance */
195	mrc	p15, 0, r0, c0, c1, 4		@ Read ID_MMFR0
196	and	r0, r0, #(MMFR0_PMSA)		@ PMSA field
197	teq	r0, #(MMFR0_PMSAv7)		@ PMSA v7
198	bne	__error_p			@ Fail: ARM_MPU on NOT v7 PMSA
199
200	/* Determine whether the D/I-side memory map is unified. We set the
201	 * flags here and continue to use them for the rest of this function */
202	mrc	p15, 0, r0, c0, c0, 4		@ MPUIR
203	ands	r5, r0, #MPUIR_DREGION_SZMASK	@ 0 size d region => No MPU
204	beq	__error_p			@ Fail: ARM_MPU and no MPU
205	tst	r0, #MPUIR_nU			@ MPUIR_nU = 0 for unified
206
207	/* Setup second region first to free up r6 */
208	set_region_nr r0, #MPU_RAM_REGION
209	isb
210	/* Full access from PL0, PL1, shared for CONFIG_SMP, cacheable */
211	ldr	r0, =PLAT_PHYS_OFFSET		@ RAM starts at PHYS_OFFSET
212	ldr	r5,=(MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL)
213
214	setup_region r0, r5, r6, MPU_DATA_SIDE	@ PHYS_OFFSET, shared, enabled
215	beq	1f				@ Memory-map not unified
216	setup_region r0, r5, r6, MPU_INSTR_SIDE @ PHYS_OFFSET, shared, enabled
2171:	isb
218
219	/* First/background region */
220	set_region_nr r0, #MPU_BG_REGION
221	isb
222	/* Execute Never,  strongly ordered, inaccessible to PL0, rw PL1  */
223	mov	r0, #0				@ BG region starts at 0x0
224	ldr	r5,=(MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA)
225	mov	r6, #MPU_RSR_ALL_MEM		@ 4GB region, enabled
226
227	setup_region r0, r5, r6, MPU_DATA_SIDE	@ 0x0, BG region, enabled
228	beq	2f				@ Memory-map not unified
229	setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled
2302:	isb
231
232	/* Vectors region */
233	set_region_nr r0, #MPU_VECTORS_REGION
234	isb
235	/* Shared, inaccessible to PL0, rw PL1 */
236	mov	r0, #CONFIG_VECTORS_BASE	@ Cover from VECTORS_BASE
237	ldr	r5,=(MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL)
238	/* Writing N to bits 5:1 (RSR_SZ) --> region size 2^N+1 */
239	mov	r6, #(((2 * PAGE_SHIFT - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN)
240
241	setup_region r0, r5, r6, MPU_DATA_SIDE	@ VECTORS_BASE, PL0 NA, enabled
242	beq	3f				@ Memory-map not unified
243	setup_region r0, r5, r6, MPU_INSTR_SIDE	@ VECTORS_BASE, PL0 NA, enabled
2443:	isb
245
246	/* Enable the MPU */
247	mrc	p15, 0, r0, c1, c0, 0		@ Read SCTLR
248	bic     r0, r0, #CR_BR			@ Disable the 'default mem-map'
249	orr	r0, r0, #CR_M			@ Set SCTRL.M (MPU on)
250	mcr	p15, 0, r0, c1, c0, 0		@ Enable MPU
251	isb
252	ret	lr
253ENDPROC(__setup_mpu)
254#endif
255#include "head-common.S"
256