xref: /linux/arch/m68k/coldfire/head.S (revision 498495dba268b20e8eadd7fe93c140c68b6cc9d2) 
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/*****************************************************************************/
300