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192.168.1.100 / T800 / 31b93824e21ac09e58a24ebf7ac559e7e77676e1 / . / src / kernel / linux / v4.19 / arch / m68k / coldfire / head.S
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xjb04a4022021-11-25 15:01:52 +0800[diff] [blame]1/* SPDX-License-Identifier: GPL-2.0 */
2/*****************************************************************************/
3
4/*
5 * head.S -- common startup code for ColdFire CPUs.
6 *
7 * (C) Copyright 1999-2011, Greg Ungerer <gerg@snapgear.com>.
8 */
9
10/*****************************************************************************/
11
12#include <linux/linkage.h>
13#include <linux/init.h>
14#include <asm/asm-offsets.h>
15#include <asm/coldfire.h>
16#include <asm/mcfsim.h>
17#include <asm/mcfmmu.h>
18#include <asm/thread_info.h>
19
20/*****************************************************************************/
21
22/*
23 * If we don't have a fixed memory size, then lets build in code
24 * to auto detect the DRAM size. Obviously this is the preferred
25 * method, and should work for most boards. It won't work for those
26 * that do not have their RAM starting at address 0, and it only
27 * works on SDRAM (not boards fitted with SRAM).
28 */
29#if CONFIG_RAMSIZE != 0
30.macro GET_MEM_SIZE
31 movel #CONFIG_RAMSIZE,%d0 /* hard coded memory size */
32.endm
33
34#elif defined(CONFIG_M5206) || defined(CONFIG_M5206e) || \
35 defined(CONFIG_M5249) || defined(CONFIG_M525x) || \
36 defined(CONFIG_M527x) || defined(CONFIG_M528x) || \
37 defined(CONFIG_M5307) || defined(CONFIG_M5407)
38/*
39 * Not all these devices have exactly the same DRAM controller,
40 * but the DCMR register is virtually identical - give or take
41 * a couple of bits. The only exception is the 5272 devices, their
42 * DRAM controller is quite different.
43 */
44.macro GET_MEM_SIZE
45 movel MCFSIM_DMR0,%d0 /* get mask for 1st bank */
46 btst #0,%d0 /* check if region enabled */
47 beq 1f
48 andl #0xfffc0000,%d0
49 beq 1f
50 addl #0x00040000,%d0 /* convert mask to size */
511:
52 movel MCFSIM_DMR1,%d1 /* get mask for 2nd bank */
53 btst #0,%d1 /* check if region enabled */
54 beq 2f
55 andl #0xfffc0000,%d1
56 beq 2f
57 addl #0x00040000,%d1
58 addl %d1,%d0 /* total mem size in d0 */
592:
60.endm
61
62#elif defined(CONFIG_M5272)
63.macro GET_MEM_SIZE
64 movel MCFSIM_CSOR7,%d0 /* get SDRAM address mask */
65 andil #0xfffff000,%d0 /* mask out chip select options */
66 negl %d0 /* negate bits */
67.endm
68
69#elif defined(CONFIG_M520x)
70.macro GET_MEM_SIZE
71 clrl %d0
72 movel MCFSIM_SDCS0, %d2 /* Get SDRAM chip select 0 config */
73 andl #0x1f, %d2 /* Get only the chip select size */
74 beq 3f /* Check if it is enabled */
75 addql #1, %d2 /* Form exponent */
76 moveql #1, %d0
77 lsll %d2, %d0 /* 2 ^ exponent */
783:
79 movel MCFSIM_SDCS1, %d2 /* Get SDRAM chip select 1 config */
80 andl #0x1f, %d2 /* Get only the chip select size */
81 beq 4f /* Check if it is enabled */
82 addql #1, %d2 /* Form exponent */
83 moveql #1, %d1
84 lsll %d2, %d1 /* 2 ^ exponent */
85 addl %d1, %d0 /* Total size of SDRAM in d0 */
864:
87.endm
88
89#else
90#error "ERROR: I don't know how to probe your boards memory size?"
91#endif
92
93/*****************************************************************************/
94
95/*
96 * Boards and platforms can do specific early hardware setup if
97 * they need to. Most don't need this, define away if not required.
98 */
99#ifndef PLATFORM_SETUP
100#define PLATFORM_SETUP
101#endif
102
103/*****************************************************************************/
104
105.global _start
106.global _rambase
107.global _ramvec
108.global _ramstart
109.global _ramend
110#if defined(CONFIG_UBOOT)
111.global _init_sp
112#endif
113
114/*****************************************************************************/
115
116.data
117
118/*
119 * During startup we store away the RAM setup. These are not in the
120 * bss, since their values are determined and written before the bss
121 * has been cleared.
122 */
123_rambase:
124.long 0
125_ramvec:
126.long 0
127_ramstart:
128.long 0
129_ramend:
130.long 0
131#if defined(CONFIG_UBOOT)
132_init_sp:
133.long 0
134#endif
135
136/*****************************************************************************/
137
138__HEAD
139
140#ifdef CONFIG_MMU
141_start0:
142 jmp _start
143.global kernel_pg_dir
144.equ kernel_pg_dir,_start0
145.equ .,_start0+0x1000
146#endif
147
148/*
149 * This is the codes first entry point. This is where it all
150 * begins...
151 */
152
153_start:
154 nop /* filler */
155 movew #0x2700, %sr /* no interrupts */
156 movel #CACHE_INIT,%d0 /* disable cache */
157 movec %d0,%CACR
158 nop
159#if defined(CONFIG_UBOOT)
160 movel %sp,_init_sp /* save initial stack pointer */
161#endif
162#ifdef CONFIG_MBAR
163 movel #CONFIG_MBAR+1,%d0 /* configured MBAR address */
164 movec %d0,%MBAR /* set it */
165#endif
166
167 /*
168 * Do any platform or board specific setup now. Most boards
169 * don't need anything. Those exceptions are define this in
170 * their board specific includes.
171 */
172 PLATFORM_SETUP
173
174 /*
175 * Create basic memory configuration. Set VBR accordingly,
176 * and size memory.
177 */
178 movel #CONFIG_VECTORBASE,%a7
179 movec %a7,%VBR /* set vectors addr */
180 movel %a7,_ramvec
181
182 movel #CONFIG_RAMBASE,%a7 /* mark the base of RAM */
183 movel %a7,_rambase
184
185 GET_MEM_SIZE /* macro code determines size */
186 addl %a7,%d0
187 movel %d0,_ramend /* set end ram addr */
188
189 /*
190 * Now that we know what the memory is, lets enable cache
191 * and get things moving. This is Coldfire CPU specific. Not
192 * all version cores have identical cache register setup. But
193 * it is very similar. Define the exact settings in the headers
194 * then the code here is the same for all.
195 */
196 movel #ACR0_MODE,%d0 /* set RAM region for caching */
197 movec %d0,%ACR0
198 movel #ACR1_MODE,%d0 /* anything else to cache? */
199 movec %d0,%ACR1
200#ifdef ACR2_MODE
201 movel #ACR2_MODE,%d0
202 movec %d0,%ACR2
203 movel #ACR3_MODE,%d0
204 movec %d0,%ACR3
205#endif
206 movel #CACHE_MODE,%d0 /* enable cache */
207 movec %d0,%CACR
208 nop
209
210#ifdef CONFIG_MMU
211 /*
212 * Identity mapping for the kernel region.
213 */
214 movel #(MMUBASE+1),%d0 /* enable MMUBAR registers */
215 movec %d0,%MMUBAR
216 movel #MMUOR_CA,%d0 /* clear TLB entries */
217 movel %d0,MMUOR
218 movel #0,%d0 /* set ASID to 0 */
219 movec %d0,%asid
220
221 movel #MMUCR_EN,%d0 /* Enable the identity map */
222 movel %d0,MMUCR
223 nop /* sync i-pipeline */
224
225 movel #_vstart,%a0 /* jump to "virtual" space */
226 jmp %a0@
227_vstart:
228#endif /* CONFIG_MMU */
229
230#ifdef CONFIG_ROMFS_FS
231 /*
232 * Move ROM filesystem above bss :-)
233 */
234 lea __bss_start,%a0 /* get start of bss */
235 lea __bss_stop,%a1 /* set up destination */
236 movel %a0,%a2 /* copy of bss start */
237
238 movel 8(%a0),%d0 /* get size of ROMFS */
239 addql #8,%d0 /* allow for rounding */
240 andl #0xfffffffc, %d0 /* whole words */
241
242 addl %d0,%a0 /* copy from end */
243 addl %d0,%a1 /* copy from end */
244 movel %a1,_ramstart /* set start of ram */
245
246_copy_romfs:
247 movel -(%a0),%d0 /* copy dword */
248 movel %d0,-(%a1)
249 cmpl %a0,%a2 /* check if at end */
250 bne _copy_romfs
251
252#else /* CONFIG_ROMFS_FS */
253 lea __bss_stop,%a1
254 movel %a1,_ramstart
255#endif /* CONFIG_ROMFS_FS */
256
257
258 /*
259 * Zero out the bss region.
260 */
261 lea __bss_start,%a0 /* get start of bss */
262 lea __bss_stop,%a1 /* get end of bss */
263 clrl %d0 /* set value */
264_clear_bss:
265 movel %d0,(%a0)+ /* clear each word */
266 cmpl %a0,%a1 /* check if at end */
267 bne _clear_bss
268
269 /*
270 * Load the current task pointer and stack.
271 */
272 lea init_thread_union,%a0
273 lea THREAD_SIZE(%a0),%sp
274
275#ifdef CONFIG_MMU
276.global m68k_cputype
277.global m68k_mmutype
278.global m68k_fputype
279.global m68k_machtype
280 movel #CPU_COLDFIRE,%d0
281 movel %d0,m68k_cputype /* Mark us as a ColdFire */
282 movel #MMU_COLDFIRE,%d0
283 movel %d0,m68k_mmutype
284 movel #FPUTYPE,%d0
285 movel %d0,m68k_fputype /* Mark FPU type */
286 movel #MACHINE,%d0
287 movel %d0,m68k_machtype /* Mark machine type */
288 lea init_task,%a2 /* Set "current" init task */
289#endif
290
291 /*
292 * Assembler start up done, start code proper.
293 */
294 jsr start_kernel /* start Linux kernel */
295
296_exit:
297 jmp _exit /* should never get here */
298
299/*****************************************************************************/