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wdenk281e00a2004-08-01 22:48:16 +00001/*
2 * Copyright (C) 2004 Sascha Hauer, Synertronixx GmbH
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
17 * 02111-1307, USA.
18 *
19 */
20
21#include <config.h>
22#include <version.h>
23#include <asm/arch/imx-regs.h>
24
wdenk400558b2005-04-02 23:52:25 +000025.globl lowlevel_init
26lowlevel_init:
wdenk281e00a2004-08-01 22:48:16 +000027
28 mov r10, lr
29
30/* Change PERCLK1DIV to 14 ie 14+1 */
31 ldr r0, =PCDR
32 ldr r1, =CFG_PCDR_VAL
33 str r1, [r0]
34
35/* set MCU PLL Control Register 0 */
36
37 ldr r0, =MPCTL0
38 ldr r1, =CFG_MPCTL0_VAL
39 str r1, [r0]
40
41/* set mpll restart bit */
42 ldr r0, =CSCR
43 ldr r1, [r0]
44 orr r1,r1,#(1<<21)
45 str r1, [r0]
46
47 mov r2,#0x10
481:
49 mov r3,#0x2000
502:
51 subs r3,r3,#1
52 bne 2b
53
54 subs r2,r2,#1
55 bne 1b
56
57/* set System PLL Control Register 0 */
58
59 ldr r0, =SPCTL0
60 ldr r1, =CFG_SPCTL0_VAL
61 str r1, [r0]
62
63/* set spll restart bit */
64 ldr r0, =CSCR
65 ldr r1, [r0]
66 orr r1,r1,#(1<<22)
67 str r1, [r0]
68
69 mov r2,#0x10
701:
71 mov r3,#0x2000
722:
73 subs r3,r3,#1
74 bne 2b
75
76 subs r2,r2,#1
77 bne 1b
78
79 ldr r0, =CSCR
80 ldr r1, =CFG_CSCR_VAL
81 str r1, [r0]
82
83/* I have now read the ARM920 DataSheet back-to-Back, and have stumbled upon
84 *this.....
85 *
86 * It would appear that from a Cold-Boot the ARM920T enters "FastBus" mode CP15
87 * register 1, this stops it using the output of the PLL and thus runs at the
88 * slow rate. Unless you place the Core into "Asynch" mode, the CPU will never
89 * use the value set in the CM_OSC registers...regardless of what you set it
90 * too! Thus, although i thought i was running at 140MHz, i'm actually running
91 * at 40!..
92
93 * Slapping this into my bootloader does the trick...
94
95 * MRC p15,0,r0,c1,c0,0 ; read core configuration register
96 * ORR r0,r0,#0xC0000000 ; set asynchronous clocks and not fastbus mode
97 * MCR p15,0,r0,c1,c0,0 ; write modified value to core configuration
98 * register
99 */
100 MRC p15,0,r0,c1,c0,0
101 ORR r0,r0,#0xC0000000
102 MCR p15,0,r0,c1,c0,0
103
104 ldr r0, =GPR(0)
105 ldr r1, =CFG_GPR_A_VAL
106 str r1, [r0]
107
108 ldr r0, =GIUS(0)
109 ldr r1, =CFG_GIUS_A_VAL
110 str r1, [r0]
111
112/* CS3 becomes CS3 by clearing reset default bit 1 in FMCR */
113
114 ldr r0, =FMCR
115 ldr r1, =CFG_FMCR_VAL
116 str r1, [r0]
117
118 ldr r0, =CS0U
119 ldr r1, =CFG_CS0U_VAL
120 str r1, [r0]
121
122 ldr r0, =CS0L
123 ldr r1, =CFG_CS0L_VAL
124 str r1, [r0]
125
126 ldr r0, =CS1U
127 ldr r1, =CFG_CS1U_VAL
128 str r1, [r0]
129
130 ldr r0, =CS1L
131 ldr r1, =CFG_CS1L_VAL
132 str r1, [r0]
133
134 ldr r0, =CS2U
135 ldr r1, =CFG_CS2U_VAL
136 str r1, [r0]
137
138 ldr r0, =CS2L
139 ldr r1, =CFG_CS2L_VAL
140 str r1, [r0]
141
142 ldr r0, =CS3U
143 ldr r1, =CFG_CS3U_VAL
144 str r1, [r0]
145
146 ldr r0, =CS3L
147 ldr r1, =CFG_CS3L_VAL
148 str r1, [r0]
149
150 ldr r0, =CS4U
151 ldr r1, =CFG_CS4U_VAL
152 str r1, [r0]
153
154 ldr r0, =CS4L
155 ldr r1, =CFG_CS4L_VAL
156 str r1, [r0]
157
158 ldr r0, =CS5U
159 ldr r1, =CFG_CS5U_VAL
160 str r1, [r0]
161
162 ldr r0, =CS5L
163 ldr r1, =CFG_CS5L_VAL
164 str r1, [r0]
165
166/* SDRAM Setup */
167
168 ldr r0, =SDCTL0
169 ldr r1, =PRECHARGE_CMD
170 str r1, [r0]
171
172 ldr r0, =0x08200000
173 ldr r1, =0x0 /* Issue Precharge all Command */
174 str r1, [r0]
175
176 ldr r0, =SDCTL0
177 ldr r1, =AUTOREFRESH_CMD
178 str r1, [r0]
179
180 ldr r0, =0x08000000
181 ldr r1, =0x0 /* Issue AutoRefresh Command */
182 str r1, [r0]
183 str r1, [r0]
184 str r1, [r0]
185 str r1, [r0]
186 str r1, [r0]
187 str r1, [r0]
188 str r1, [r0]
189 str r1, [r0]
190
191 ldr r0, =SDCTL0
192 ldr r1, =0xb10a8300
193 str r1, [r0]
194
195 ldr r0, =0x08223000 /* CAS Latency 2 */
196 ldr r1, =0x0 /* Issue Mode Register Command, Burst Length = 8 */
197 str r1, [r0]
198
199 ldr r0, =SDCTL0
200 ldr r1, =0x810a8200 /* Set to Normal Mode CAS 2 */
201 str r1, [r0]
202
203 mov pc,r10