blob: 30212e92818794e3b125d7b3cba2cdaa7fd7f8ec [file] [log] [blame]
Mike Frysinger9171fc82008-03-30 15:46:13 -04001/*
2 * U-boot - start.S Startup file for Blackfin u-boot
3 *
4 * Copyright (c) 2005-2007 Analog Devices Inc.
5 *
6 * This file is based on head.S
7 * Copyright (c) 2003 Metrowerks/Motorola
8 * Copyright (C) 1998 D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
9 * Kenneth Albanowski <kjahds@kjahds.com>,
10 * The Silver Hammer Group, Ltd.
11 * (c) 1995, Dionne & Associates
12 * (c) 1995, DKG Display Tech.
13 *
14 * See file CREDITS for list of people who contributed to this
15 * project.
16 *
17 * This program is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public License as
19 * published by the Free Software Foundation; either version 2 of
20 * the License, or (at your option) any later version.
21 *
22 * This program is distributed in the hope that it will be useful,
23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25 * GNU General Public License for more details.
26 *
27 * You should have received a copy of the GNU General Public License
28 * along with this program; if not, write to the Free Software
29 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
30 * MA 02110-1301 USA
31 */
32
33#include <config.h>
34#include <asm/blackfin.h>
35#include <asm/mach-common/bits/core.h>
36#include <asm/mach-common/bits/dma.h>
37#include <asm/mach-common/bits/pll.h>
38
39#include "serial.h"
40
41/* It may seem odd that we make calls to functions even though we haven't
42 * relocated ourselves yet out of {flash,ram,wherever}. This is OK because
43 * the "call" instruction in the Blackfin architecture is actually PC
44 * relative. So we can call functions all we want and not worry about them
45 * not being relocated yet.
46 */
47
48.text
49ENTRY(_start)
50
51 /* Set our initial stack to L1 scratch space */
52 sp.l = LO(L1_SRAM_SCRATCH + L1_SRAM_SCRATCH_SIZE);
53 sp.h = HI(L1_SRAM_SCRATCH + L1_SRAM_SCRATCH_SIZE);
54
55#ifdef CONFIG_HW_WATCHDOG
56# ifndef CONFIG_HW_WATCHDOG_TIMEOUT_START
57# define CONFIG_HW_WATCHDOG_TIMEOUT_START 5000
58# endif
59 /* Program the watchdog with an initial timeout of ~5 seconds.
60 * That should be long enough to bootstrap ourselves up and
61 * then the common u-boot code can take over.
62 */
63 P0.L = LO(WDOG_CNT);
64 P0.H = HI(WDOG_CNT);
65 R0.L = 0;
66 R0.H = HI(MSEC_TO_SCLK(CONFIG_HW_WATCHDOG_TIMEOUT_START));
67 [P0] = R0;
68 /* fire up the watchdog - R0.L above needs to be 0x0000 */
69 W[P0 + (WDOG_CTL - WDOG_CNT)] = R0;
70#endif
71
72 /* Turn on the serial for debugging the init process */
73 serial_early_init
74 serial_early_set_baud
75
76 serial_early_puts("Init Registers");
77
78 /* Disable nested interrupts and enable CYCLES for udelay() */
79 R0 = CCEN | 0x30;
80 SYSCFG = R0;
81
82 /* Zero out registers required by Blackfin ABI.
83 * http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
84 */
85 r1 = 0 (x);
86 /* Disable circular buffers */
87 l0 = r1;
88 l1 = r1;
89 l2 = r1;
90 l3 = r1;
91 /* Disable hardware loops in case we were started by 'go' */
92 lc0 = r1;
93 lc1 = r1;
94
95 /* Save RETX so we can pass it while booting Linux */
96 r7 = RETX;
97
98#if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_BYPASS)
99 /* In bypass mode, we don't have an LDR with an init block
100 * so we need to explicitly call it ourselves. This will
101 * reprogram our clocks and setup our async banks.
102 */
103 /* XXX: we should DMA this into L1, put external memory into
104 * self refresh, and then jump there ...
105 */
106 call _get_pc;
107 r3 = 0x0;
108 r3.h = 0x2000;
109 cc = r0 < r3 (iu);
110 if cc jump .Lproc_initialized;
111
112 serial_early_puts("Program Clocks");
113
114 call _initcode;
115
116 /* Since we reprogrammed SCLK, we need to update the serial divisor */
117 serial_early_set_baud
118
119.Lproc_initialized:
120#endif
121
122 /* Inform upper layers if we had to do the relocation ourselves.
123 * This allows us to detect whether we were loaded by 'go 0x1000'
124 * or by the bootrom from an LDR. "r6" is "loaded_from_ldr".
125 */
126 r6 = 1 (x);
127
128 /* Relocate from wherever are (FLASH/RAM/etc...) to the
129 * hardcoded monitor location in the end of RAM.
130 */
131 serial_early_puts("Relocate");
132 call _get_pc;
133.Loffset:
134 r2.l = .Loffset;
135 r2.h = .Loffset;
136 r3.l = _start;
137 r3.h = _start;
138 r1 = r2 - r3;
139
140 r0 = r0 - r1;
141
142 cc = r0 == r3;
143 if cc jump .Lnorelocate;
144
145 r6 = 0 (x);
146 p1 = r0;
147
148 p2.l = LO(CFG_MONITOR_BASE);
149 p2.h = HI(CFG_MONITOR_BASE);
150
151 p3 = 0x04;
152 p4.l = LO(CFG_MONITOR_BASE + CFG_MONITOR_LEN);
153 p4.h = HI(CFG_MONITOR_BASE + CFG_MONITOR_LEN);
154.Lloop1:
155 r1 = [p1 ++ p3];
156 [p2 ++ p3] = r1;
157 cc=p2==p4;
158 if !cc jump .Lloop1;
159
160 /* Initialize BSS section ... we know that memset() does not
161 * use the BSS, so it is safe to call here. The bootrom LDR
162 * takes care of clearing things for us.
163 */
164 serial_early_puts("Zero BSS");
165 r0.l = __bss_start;
166 r0.h = __bss_start;
167 r1 = 0 (x);
168 r2.l = __bss_end;
169 r2.h = __bss_end;
170 r2 = r2 - r0;
171 call _memset;
172
173.Lnorelocate:
174
175 /* Setup the actual stack in external memory */
176 r0.h = HI(CONFIG_STACKBASE);
177 r0.l = LO(CONFIG_STACKBASE);
178 sp = r0;
179 fp = sp;
180
181 /* Now lower ourselves from the highest interrupt level to
182 * the lowest. We do this by masking all interrupts but 15,
183 * setting the 15 handler to "board_init_f", raising the 15
184 * interrupt, and then returning from the highest interrupt
185 * level to the dummy "jump" until the interrupt controller
186 * services the pending 15 interrupt.
187 */
188 serial_early_puts("Lower to 15");
189 r0 = r7;
190 r1 = r6;
191 p0.l = LO(EVT15);
192 p0.h = HI(EVT15);
193 p1.l = _cpu_init_f;
194 p1.h = _cpu_init_f;
195 [p0] = p1;
196 p2.l = LO(IMASK);
197 p2.h = HI(IMASK);
198 p3.l = LO(EVT_IVG15);
199 p3.h = HI(EVT_IVG15);
200 [p2] = p3;
201 raise 15;
202 p4.l = .LWAIT_HERE;
203 p4.h = .LWAIT_HERE;
204 reti = p4;
205 rti;
206
207.LWAIT_HERE:
208 jump .LWAIT_HERE;
209ENDPROC(_start)
210
211LENTRY(_get_pc)
212 r0 = rets;
213#if ANOMALY_05000371
214 NOP;
215 NOP;
216 NOP;
217#endif
218 rts;
219ENDPROC(_get_pc)