aboutsummaryrefslogtreecommitdiffstats
path: root/arch/microblaze/kernel/head.S
blob: 77320b8fc16a8c2229192343b3b527613b3a3650 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
/*
 * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2007-2009 PetaLogix
 * Copyright (C) 2006 Atmark Techno, Inc.
 *
 * MMU code derived from arch/ppc/kernel/head_4xx.S:
 *    Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org>
 *      Initial PowerPC version.
 *    Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu>
 *      Rewritten for PReP
 *    Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
 *      Low-level exception handers, MMU support, and rewrite.
 *    Copyright (c) 1997 Dan Malek <dmalek@jlc.net>
 *      PowerPC 8xx modifications.
 *    Copyright (c) 1998-1999 TiVo, Inc.
 *      PowerPC 403GCX modifications.
 *    Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
 *      PowerPC 403GCX/405GP modifications.
 *    Copyright 2000 MontaVista Software Inc.
 *	PPC405 modifications
 *      PowerPC 403GCX/405GP modifications.
 * 	Author: MontaVista Software, Inc.
 *         	frank_rowand@mvista.com or source@mvista.com
 * 	   	debbie_chu@mvista.com
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/page.h>
#include <linux/of_fdt.h>		/* for OF_DT_HEADER */

#ifdef CONFIG_MMU
#include <asm/setup.h> /* COMMAND_LINE_SIZE */
#include <asm/mmu.h>
#include <asm/processor.h>

.section .data
.global empty_zero_page
.align 12
empty_zero_page:
	.space	PAGE_SIZE
.global swapper_pg_dir
swapper_pg_dir:
	.space	PAGE_SIZE

#endif /* CONFIG_MMU */

.section .rodata
.align 4
endian_check:
	.word	1

	__HEAD
ENTRY(_start)
#if CONFIG_KERNEL_BASE_ADDR == 0
	brai	TOPHYS(real_start)
	.org	0x100
real_start:
#endif

	mfs	r1, rmsr
	andi	r1, r1, ~2
	mts	rmsr, r1
/*
 * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc'
 * if the msrclr instruction is not enabled. We use this to detect
 * if the opcode is available, by issuing msrclr and then testing the result.
 * r8 == 0 - msr instructions are implemented
 * r8 != 0 - msr instructions are not implemented
 */
	msrclr	r8, 0 /* clear nothing - just read msr for test */
	cmpu	r8, r8, r1 /* r1 must contain msr reg content */

/* r7 may point to an FDT, or there may be one linked in.
   if it's in r7, we've got to save it away ASAP.
   We ensure r7 points to a valid FDT, just in case the bootloader
   is broken or non-existent */
	beqi	r7, no_fdt_arg			/* NULL pointer?  don't copy */
/* Does r7 point to a valid FDT? Load HEADER magic number */
	/* Run time Big/Little endian platform */
	/* Save 1 as word and load byte - 0 - BIG, 1 - LITTLE */
	lbui	r11, r0, TOPHYS(endian_check)
	beqid	r11, big_endian /* DO NOT break delay stop dependency */
	lw	r11, r0, r7 /* Big endian load in delay slot */
	lwr	r11, r0, r7 /* Little endian load */
big_endian:
	rsubi	r11, r11, OF_DT_HEADER	/* Check FDT header */
	beqi	r11, _prepare_copy_fdt
	or	r7, r0, r0		/* clear R7 when not valid DTB */
	bnei	r11, no_fdt_arg			/* No - get out of here */
_prepare_copy_fdt:
	or	r11, r0, r0 /* incremment */
	ori	r4, r0, TOPHYS(_fdt_start)
	ori	r3, r0, (0x4000 - 4)
_copy_fdt:
	lw	r12, r7, r11 /* r12 = r7 + r11 */
	sw	r12, r4, r11 /* addr[r4 + r11] = r12 */
	addik	r11, r11, 4 /* increment counting */
	bgtid	r3, _copy_fdt /* loop for all entries */
	addik	r3, r3, -4 /* descrement loop */
no_fdt_arg:

#ifdef CONFIG_MMU

#ifndef CONFIG_CMDLINE_BOOL
/*
 * handling command line
 * copy command line to __init_end. There is space for storing command line.
 */
	or	r6, r0, r0		/* incremment */
	ori	r4, r0, __init_end	/* load address of command line */
	tophys(r4,r4)			/* convert to phys address */
	ori	r3, r0, COMMAND_LINE_SIZE - 1 /* number of loops */
_copy_command_line:
	lbu	r2, r5, r6 /* r2=r5+r6 - r5 contain pointer to command line */
	sb	r2, r4, r6		/* addr[r4+r6]= r2*/
	addik	r6, r6, 1		/* increment counting */
	bgtid	r3, _copy_command_line	/* loop for all entries       */
	addik	r3, r3, -1		/* descrement loop */
	addik	r5, r4, 0		/* add new space for command line */
	tovirt(r5,r5)
#endif /* CONFIG_CMDLINE_BOOL */

#ifdef NOT_COMPILE
/* save bram context */
	or	r6, r0, r0				/* incremment */
	ori	r4, r0, TOPHYS(_bram_load_start)	/* save bram context */
	ori	r3, r0, (LMB_SIZE - 4)
_copy_bram:
	lw	r7, r0, r6		/* r7 = r0 + r6 */
	sw	r7, r4, r6		/* addr[r4 + r6] = r7*/
	addik	r6, r6, 4		/* increment counting */
	bgtid	r3, _copy_bram		/* loop for all entries */
	addik	r3, r3, -4		/* descrement loop */
#endif
	/* We have to turn on the MMU right away. */

	/*
	 * Set up the initial MMU state so we can do the first level of
	 * kernel initialization.  This maps the first 16 MBytes of memory 1:1
	 * virtual to physical.
	 */
	nop
	addik	r3, r0, MICROBLAZE_TLB_SIZE -1	/* Invalidate all TLB entries */
_invalidate:
	mts	rtlbx, r3
	mts	rtlbhi, r0			/* flush: ensure V is clear   */
	bgtid	r3, _invalidate		/* loop for all entries       */
	addik	r3, r3, -1
	/* sync */

	/* Setup the kernel PID */
	mts	rpid,r0			/* Load the kernel PID */
	nop
	bri	4

	/*
	 * We should still be executing code at physical address area
	 * RAM_BASEADDR at this point. However, kernel code is at
	 * a virtual address. So, set up a TLB mapping to cover this once
	 * translation is enabled.
	 */

	addik	r3,r0, CONFIG_KERNEL_START /* Load the kernel virtual address */
	tophys(r4,r3)			/* Load the kernel physical address */

	/*
	 * Configure and load two entries into TLB slots 0 and 1.
	 * In case we are pinning TLBs, these are reserved in by the
	 * other TLB functions.  If not reserving, then it doesn't
	 * matter where they are loaded.
	 */
	andi	r4,r4,0xfffffc00	/* Mask off the real page number */
	ori	r4,r4,(TLB_WR | TLB_EX)	/* Set the write and execute bits */

	andi	r3,r3,0xfffffc00	/* Mask off the effective page number */
	ori	r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))

	mts     rtlbx,r0		/* TLB slow 0 */

	mts	rtlblo,r4		/* Load the data portion of the entry */
	mts	rtlbhi,r3		/* Load the tag portion of the entry */

	addik	r4, r4, 0x01000000	/* Map next 16 M entries */
	addik	r3, r3, 0x01000000

	ori	r6,r0,1			/* TLB slot 1 */
	mts     rtlbx,r6

	mts	rtlblo,r4		/* Load the data portion of the entry */
	mts	rtlbhi,r3		/* Load the tag portion of the entry */

	/*
	 * Load a TLB entry for LMB, since we need access to
	 * the exception vectors, using a 4k real==virtual mapping.
	 */
	ori	r6,r0,3			/* TLB slot 3 */
	mts     rtlbx,r6

	ori	r4,r0,(TLB_WR | TLB_EX)
	ori	r3,r0,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K))

	mts	rtlblo,r4		/* Load the data portion of the entry */
	mts	rtlbhi,r3		/* Load the tag portion of the entry */

	/*
	 * We now have the lower 16 Meg of RAM mapped into TLB entries, and the
	 * caches ready to work.
	 */
turn_on_mmu:
	ori	r15,r0,start_here
	ori	r4,r0,MSR_KERNEL_VMS
	mts	rmsr,r4
	nop
	rted	r15,0			/* enables MMU */
	nop

start_here:
#endif /* CONFIG_MMU */

	/* Initialize small data anchors */
	addik	r13, r0, _KERNEL_SDA_BASE_
	addik	r2, r0, _KERNEL_SDA2_BASE_

	/* Initialize stack pointer */
	addik	r1, r0, init_thread_union + THREAD_SIZE - 4

	/* Initialize r31 with current task address */
	addik	r31, r0, init_task

	/*
	 * Call platform dependent initialize function.
	 * Please see $(ARCH)/mach-$(SUBARCH)/setup.c for
	 * the function.
	 */
	addik	r9, r0, machine_early_init
	brald	r15, r9
	nop

#ifndef CONFIG_MMU
	addik	r15, r0, machine_halt
	braid	start_kernel
	nop
#else
	/*
	 * Initialize the MMU.
	 */
	bralid	r15, mmu_init
	nop

	/* Go back to running unmapped so we can load up new values
	 * and change to using our exception vectors.
	 * On the MicroBlaze, all we invalidate the used TLB entries to clear
	 * the old 16M byte TLB mappings.
	 */
	ori	r15,r0,TOPHYS(kernel_load_context)
	ori	r4,r0,MSR_KERNEL
	mts	rmsr,r4
	nop
	bri	4
	rted	r15,0
	nop

	/* Load up the kernel context */
kernel_load_context:
	# Keep entry 0 and 1 valid. Entry 3 mapped to LMB can go away.
	ori	r5,r0,3
	mts     rtlbx,r5
	nop
	mts	rtlbhi,r0
	nop
	addi	r15, r0, machine_halt
	ori	r17, r0, start_kernel
	ori	r4, r0, MSR_KERNEL_VMS
	mts	rmsr, r4
	nop
	rted	r17, 0		/* enable MMU and jump to start_kernel */
	nop
#endif /* CONFIG_MMU */