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6d5af1a3 MS |
1 | /* |
2 | * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu> | |
3 | * Copyright (C) 2007-2009 PetaLogix | |
4 | * Copyright (C) 2006 Atmark Techno, Inc. | |
5 | * | |
5846cc60 MS |
6 | * MMU code derived from arch/ppc/kernel/head_4xx.S: |
7 | * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org> | |
8 | * Initial PowerPC version. | |
9 | * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu> | |
10 | * Rewritten for PReP | |
11 | * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au> | |
12 | * Low-level exception handers, MMU support, and rewrite. | |
13 | * Copyright (c) 1997 Dan Malek <dmalek@jlc.net> | |
14 | * PowerPC 8xx modifications. | |
15 | * Copyright (c) 1998-1999 TiVo, Inc. | |
16 | * PowerPC 403GCX modifications. | |
17 | * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> | |
18 | * PowerPC 403GCX/405GP modifications. | |
19 | * Copyright 2000 MontaVista Software Inc. | |
20 | * PPC405 modifications | |
21 | * PowerPC 403GCX/405GP modifications. | |
22 | * Author: MontaVista Software, Inc. | |
23 | * frank_rowand@mvista.com or source@mvista.com | |
24 | * debbie_chu@mvista.com | |
25 | * | |
6d5af1a3 MS |
26 | * This file is subject to the terms and conditions of the GNU General Public |
27 | * License. See the file "COPYING" in the main directory of this archive | |
28 | * for more details. | |
29 | */ | |
30 | ||
31 | #include <linux/linkage.h> | |
32 | #include <asm/thread_info.h> | |
33 | #include <asm/page.h> | |
d8678b58 | 34 | #include <linux/of_fdt.h> /* for OF_DT_HEADER */ |
6d5af1a3 | 35 | |
5846cc60 MS |
36 | #ifdef CONFIG_MMU |
37 | #include <asm/setup.h> /* COMMAND_LINE_SIZE */ | |
38 | #include <asm/mmu.h> | |
39 | #include <asm/processor.h> | |
40 | ||
41 | .data | |
42 | .global empty_zero_page | |
43 | .align 12 | |
44 | empty_zero_page: | |
45 | .space 4096 | |
46 | .global swapper_pg_dir | |
47 | swapper_pg_dir: | |
48 | .space 4096 | |
49 | ||
50 | #endif /* CONFIG_MMU */ | |
51 | ||
6d5af1a3 MS |
52 | .text |
53 | ENTRY(_start) | |
ee68f174 MS |
54 | #if CONFIG_KERNEL_BASE_ADDR == 0 |
55 | brai TOPHYS(real_start) | |
56 | .org 0x100 | |
57 | real_start: | |
58 | #endif | |
59 | ||
6d5af1a3 MS |
60 | mfs r1, rmsr |
61 | andi r1, r1, ~2 | |
62 | mts rmsr, r1 | |
2622434e MS |
63 | /* |
64 | * Here is checking mechanism which check if Microblaze has msr instructions | |
65 | * We load msr and compare it with previous r1 value - if is the same, | |
66 | * msr instructions works if not - cpu don't have them. | |
67 | */ | |
9002062f MS |
68 | /* r8=0 - I have msr instr, 1 - I don't have them */ |
69 | rsubi r0, r0, 1 /* set the carry bit */ | |
70 | msrclr r0, 0x4 /* try to clear it */ | |
71 | /* read the carry bit, r8 will be '0' if msrclr exists */ | |
72 | addik r8, r0, 0 | |
2622434e | 73 | |
909964ec JW |
74 | /* r7 may point to an FDT, or there may be one linked in. |
75 | if it's in r7, we've got to save it away ASAP. | |
76 | We ensure r7 points to a valid FDT, just in case the bootloader | |
77 | is broken or non-existent */ | |
78 | beqi r7, no_fdt_arg /* NULL pointer? don't copy */ | |
79 | lw r11, r0, r7 /* Does r7 point to a */ | |
80 | rsubi r11, r11, OF_DT_HEADER /* valid FDT? */ | |
ea3fd146 MS |
81 | beqi r11, _prepare_copy_fdt |
82 | or r7, r0, r0 /* clear R7 when not valid DTB */ | |
909964ec | 83 | bnei r11, no_fdt_arg /* No - get out of here */ |
ea3fd146 | 84 | _prepare_copy_fdt: |
6d5af1a3 | 85 | or r11, r0, r0 /* incremment */ |
909964ec | 86 | ori r4, r0, TOPHYS(_fdt_start) |
6d5af1a3 MS |
87 | ori r3, r0, (0x4000 - 4) |
88 | _copy_fdt: | |
89 | lw r12, r7, r11 /* r12 = r7 + r11 */ | |
90 | sw r12, r4, r11 /* addr[r4 + r11] = r12 */ | |
91 | addik r11, r11, 4 /* increment counting */ | |
92 | bgtid r3, _copy_fdt /* loop for all entries */ | |
93 | addik r3, r3, -4 /* descrement loop */ | |
94 | no_fdt_arg: | |
95 | ||
5846cc60 MS |
96 | #ifdef CONFIG_MMU |
97 | ||
98 | #ifndef CONFIG_CMDLINE_BOOL | |
99 | /* | |
100 | * handling command line | |
101 | * copy command line to __init_end. There is space for storing command line. | |
102 | */ | |
103 | or r6, r0, r0 /* incremment */ | |
104 | ori r4, r0, __init_end /* load address of command line */ | |
105 | tophys(r4,r4) /* convert to phys address */ | |
106 | ori r3, r0, COMMAND_LINE_SIZE - 1 /* number of loops */ | |
107 | _copy_command_line: | |
3f218935 MS |
108 | lbu r2, r5, r6 /* r2=r5+r6 - r5 contain pointer to command line */ |
109 | sb r2, r4, r6 /* addr[r4+r6]= r2*/ | |
5846cc60 MS |
110 | addik r6, r6, 1 /* increment counting */ |
111 | bgtid r3, _copy_command_line /* loop for all entries */ | |
112 | addik r3, r3, -1 /* descrement loop */ | |
113 | addik r5, r4, 0 /* add new space for command line */ | |
114 | tovirt(r5,r5) | |
115 | #endif /* CONFIG_CMDLINE_BOOL */ | |
116 | ||
117 | #ifdef NOT_COMPILE | |
118 | /* save bram context */ | |
119 | or r6, r0, r0 /* incremment */ | |
120 | ori r4, r0, TOPHYS(_bram_load_start) /* save bram context */ | |
121 | ori r3, r0, (LMB_SIZE - 4) | |
122 | _copy_bram: | |
123 | lw r7, r0, r6 /* r7 = r0 + r6 */ | |
124 | sw r7, r4, r6 /* addr[r4 + r6] = r7*/ | |
125 | addik r6, r6, 4 /* increment counting */ | |
126 | bgtid r3, _copy_bram /* loop for all entries */ | |
127 | addik r3, r3, -4 /* descrement loop */ | |
128 | #endif | |
129 | /* We have to turn on the MMU right away. */ | |
130 | ||
131 | /* | |
132 | * Set up the initial MMU state so we can do the first level of | |
133 | * kernel initialization. This maps the first 16 MBytes of memory 1:1 | |
134 | * virtual to physical. | |
135 | */ | |
136 | nop | |
0691c97d | 137 | addik r3, r0, MICROBLAZE_TLB_SIZE -1 /* Invalidate all TLB entries */ |
5846cc60 MS |
138 | _invalidate: |
139 | mts rtlbx, r3 | |
140 | mts rtlbhi, r0 /* flush: ensure V is clear */ | |
141 | bgtid r3, _invalidate /* loop for all entries */ | |
142 | addik r3, r3, -1 | |
143 | /* sync */ | |
144 | ||
137d0795 MS |
145 | /* Setup the kernel PID */ |
146 | mts rpid,r0 /* Load the kernel PID */ | |
147 | nop | |
148 | bri 4 | |
149 | ||
5846cc60 MS |
150 | /* |
151 | * We should still be executing code at physical address area | |
152 | * RAM_BASEADDR at this point. However, kernel code is at | |
153 | * a virtual address. So, set up a TLB mapping to cover this once | |
154 | * translation is enabled. | |
155 | */ | |
156 | ||
157 | addik r3,r0, CONFIG_KERNEL_START /* Load the kernel virtual address */ | |
158 | tophys(r4,r3) /* Load the kernel physical address */ | |
159 | ||
5846cc60 MS |
160 | /* |
161 | * Configure and load two entries into TLB slots 0 and 1. | |
162 | * In case we are pinning TLBs, these are reserved in by the | |
163 | * other TLB functions. If not reserving, then it doesn't | |
164 | * matter where they are loaded. | |
165 | */ | |
166 | andi r4,r4,0xfffffc00 /* Mask off the real page number */ | |
167 | ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ | |
168 | ||
169 | andi r3,r3,0xfffffc00 /* Mask off the effective page number */ | |
170 | ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M)) | |
171 | ||
172 | mts rtlbx,r0 /* TLB slow 0 */ | |
173 | ||
174 | mts rtlblo,r4 /* Load the data portion of the entry */ | |
175 | mts rtlbhi,r3 /* Load the tag portion of the entry */ | |
176 | ||
177 | addik r4, r4, 0x01000000 /* Map next 16 M entries */ | |
178 | addik r3, r3, 0x01000000 | |
179 | ||
180 | ori r6,r0,1 /* TLB slot 1 */ | |
181 | mts rtlbx,r6 | |
182 | ||
183 | mts rtlblo,r4 /* Load the data portion of the entry */ | |
184 | mts rtlbhi,r3 /* Load the tag portion of the entry */ | |
185 | ||
186 | /* | |
187 | * Load a TLB entry for LMB, since we need access to | |
188 | * the exception vectors, using a 4k real==virtual mapping. | |
189 | */ | |
190 | ori r6,r0,3 /* TLB slot 3 */ | |
191 | mts rtlbx,r6 | |
192 | ||
193 | ori r4,r0,(TLB_WR | TLB_EX) | |
194 | ori r3,r0,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K)) | |
195 | ||
196 | mts rtlblo,r4 /* Load the data portion of the entry */ | |
197 | mts rtlbhi,r3 /* Load the tag portion of the entry */ | |
198 | ||
199 | /* | |
200 | * We now have the lower 16 Meg of RAM mapped into TLB entries, and the | |
201 | * caches ready to work. | |
202 | */ | |
203 | turn_on_mmu: | |
204 | ori r15,r0,start_here | |
205 | ori r4,r0,MSR_KERNEL_VMS | |
206 | mts rmsr,r4 | |
207 | nop | |
208 | rted r15,0 /* enables MMU */ | |
209 | nop | |
210 | ||
211 | start_here: | |
212 | #endif /* CONFIG_MMU */ | |
213 | ||
6d5af1a3 MS |
214 | /* Initialize small data anchors */ |
215 | la r13, r0, _KERNEL_SDA_BASE_ | |
216 | la r2, r0, _KERNEL_SDA2_BASE_ | |
217 | ||
218 | /* Initialize stack pointer */ | |
219 | la r1, r0, init_thread_union + THREAD_SIZE - 4 | |
220 | ||
221 | /* Initialize r31 with current task address */ | |
222 | la r31, r0, init_task | |
223 | ||
224 | /* | |
225 | * Call platform dependent initialize function. | |
226 | * Please see $(ARCH)/mach-$(SUBARCH)/setup.c for | |
227 | * the function. | |
228 | */ | |
2622434e MS |
229 | la r9, r0, machine_early_init |
230 | brald r15, r9 | |
6d5af1a3 MS |
231 | nop |
232 | ||
5846cc60 | 233 | #ifndef CONFIG_MMU |
6d5af1a3 MS |
234 | la r15, r0, machine_halt |
235 | braid start_kernel | |
236 | nop | |
5846cc60 MS |
237 | #else |
238 | /* | |
239 | * Initialize the MMU. | |
240 | */ | |
241 | bralid r15, mmu_init | |
242 | nop | |
243 | ||
244 | /* Go back to running unmapped so we can load up new values | |
245 | * and change to using our exception vectors. | |
246 | * On the MicroBlaze, all we invalidate the used TLB entries to clear | |
247 | * the old 16M byte TLB mappings. | |
248 | */ | |
249 | ori r15,r0,TOPHYS(kernel_load_context) | |
250 | ori r4,r0,MSR_KERNEL | |
251 | mts rmsr,r4 | |
252 | nop | |
253 | bri 4 | |
254 | rted r15,0 | |
255 | nop | |
256 | ||
257 | /* Load up the kernel context */ | |
258 | kernel_load_context: | |
259 | # Keep entry 0 and 1 valid. Entry 3 mapped to LMB can go away. | |
260 | ori r5,r0,3 | |
261 | mts rtlbx,r5 | |
262 | nop | |
263 | mts rtlbhi,r0 | |
264 | nop | |
265 | addi r15, r0, machine_halt | |
266 | ori r17, r0, start_kernel | |
267 | ori r4, r0, MSR_KERNEL_VMS | |
268 | mts rmsr, r4 | |
269 | nop | |
270 | rted r17, 0 /* enable MMU and jump to start_kernel */ | |
271 | nop | |
272 | #endif /* CONFIG_MMU */ |