xref: /openbmc/u-boot/arch/arm/mach-imx/imx_bootaux.c (revision db00e921)
1 /*
2  * Copyright (C) 2016 Freescale Semiconductor, Inc.
3  *
4  * SPDX-License-Identifier:	GPL-2.0+
5  */
6 
7 #include <common.h>
8 #include <command.h>
9 #include <linux/compiler.h>
10 
11 /* Allow for arch specific config before we boot */
12 int __weak arch_auxiliary_core_up(u32 core_id, u32 boot_private_data)
13 {
14 	/* please define platform specific arch_auxiliary_core_up() */
15 	return CMD_RET_FAILURE;
16 }
17 
18 /* Allow for arch specific config before we boot */
19 int __weak arch_auxiliary_core_check_up(u32 core_id)
20 {
21 	/* please define platform specific arch_auxiliary_core_check_up() */
22 	return 0;
23 }
24 
25 /*
26  * To i.MX6SX and i.MX7D, the image supported by bootaux needs
27  * the reset vector at the head for the image, with SP and PC
28  * as the first two words.
29  *
30  * Per the cortex-M reference manual, the reset vector of M4 needs
31  * to exist at 0x0 (TCMUL). The PC and SP are the first two addresses
32  * of that vector.  So to boot M4, the A core must build the M4's reset
33  * vector with getting the PC and SP from image and filling them to
34  * TCMUL. When M4 is kicked, it will load the PC and SP by itself.
35  * The TCMUL is mapped to (M4_BOOTROM_BASE_ADDR) at A core side for
36  * accessing the M4 TCMUL.
37  */
38 static int do_bootaux(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
39 {
40 	ulong addr;
41 	int ret, up;
42 
43 	if (argc < 2)
44 		return CMD_RET_USAGE;
45 
46 	up = arch_auxiliary_core_check_up(0);
47 	if (up) {
48 		printf("## Auxiliary core is already up\n");
49 		return CMD_RET_SUCCESS;
50 	}
51 
52 	addr = simple_strtoul(argv[1], NULL, 16);
53 
54 	printf("## Starting auxiliary core at 0x%08lX ...\n", addr);
55 
56 	ret = arch_auxiliary_core_up(0, addr);
57 	if (ret)
58 		return CMD_RET_FAILURE;
59 
60 	return CMD_RET_SUCCESS;
61 }
62 
63 U_BOOT_CMD(
64 	bootaux, CONFIG_SYS_MAXARGS, 1,	do_bootaux,
65 	"Start auxiliary core",
66 	""
67 );
68