1 /*
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright © 2023 Keith Packard
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following
15 * disclaimer in the documentation and/or other materials provided
16 * with the distribution.
17 *
18 * 3. Neither the name of the copyright holder nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
26 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
27 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
28 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
29 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
31 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
33 * OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 #include "../../crt0.h"
37
38 static void __attribute__((used)) __section(".init")
_cstart(void)39 _cstart(void)
40 {
41 __start();
42 }
43
44 extern char __stack[];
45
46 #if _MIPS_SZLONG == 32
47 #define LA "la"
48 #elif _MIPS_SZLONG == 64
49 #define LA "dla"
50 #else
51 #error unknown mips target
52 #endif
53
54 void __section(".init") __attribute__((used))
_start(void)55 _start(void)
56 {
57 /* Initialize stack pointer */
58 __asm__(LA " $sp,%0" : : "i" (__stack));
59
60 #ifndef __mips_soft_float
61 /* Enable FPU */
62 uint32_t cp0_status;
63 __asm__("mfc0 %0,$12" : "=r" (cp0_status));
64 cp0_status |= (1 << 29);
65 __asm__("mtc0 %0,$12" : : "r" (cp0_status));
66 #endif
67 /* Branch to C code */
68 __asm__("j _cstart");
69 __asm__("nop");
70 }
71
