imx: imx-common: introduce boot auxiliary core

To boot a auxiliary core in asymmetric multicore system, introduce the
new command "bootaux" to do it. Example of boot auxliary core from
0x70000000 where stores the boot head information that should be
parsed by auxiliary core, "bootaux 0x70000000".
Introduce Kconfig option IMX_BOOTAUX.

Signed-off-by: Ye.Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>

arch/arm/imx-common/Kconfig

@@ -11,3 +11,9 @@ config IMX_RDC
 	  i.MX Resource domain controller is used to assign masters
 	  and peripherals to differet domains. This can be used to
 	  isolate resources.
+
+config IMX_BOOTAUX
+	bool "Support boot auxiliary core"
+	depends on ARCH_MX7 || ARCH_MX6
+	help
+	  bootaux [addr] to boot auxiliary core.

arch/arm/imx-common/Makefile

@@ -28,6 +28,7 @@ obj-y 	+= cache.o init.o
 obj-$(CONFIG_CMD_SATA) += sata.o
 obj-$(CONFIG_IMX_VIDEO_SKIP) += video.o
 obj-$(CONFIG_IMX_RDC) += rdc-sema.o
+obj-$(CONFIG_IMX_BOOTAUX) += imx_bootaux.o
 obj-$(CONFIG_SECURE_BOOT)    += hab.o
 endif
 ifeq ($(SOC),$(filter $(SOC),vf610))

arch/arm/imx-common/imx_bootaux.c

+/*
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+
+/* Allow for arch specific config before we boot */
+static int __arch_auxiliary_core_up(u32 core_id, u32 boot_private_data)
+{
+	/* please define platform specific arch_auxiliary_core_up() */
+	return CMD_RET_FAILURE;
+}
+
+int arch_auxiliary_core_up(u32 core_id, u32 boot_private_data)
+	__attribute__((weak, alias("__arch_auxiliary_core_up")));
+
+/* Allow for arch specific config before we boot */
+static int __arch_auxiliary_core_check_up(u32 core_id)
+{
+	/* please define platform specific arch_auxiliary_core_check_up() */
+	return 0;
+}
+
+int arch_auxiliary_core_check_up(u32 core_id)
+	__attribute__((weak, alias("__arch_auxiliary_core_check_up")));
+
+/*
+ * To i.MX6SX and i.MX7D, the image supported by bootaux needs
+ * the reset vector at the head for the image, with SP and PC
+ * as the first two words.
+ *
+ * Per the cortex-M reference manual, the reset vector of M4 needs
+ * to exist at 0x0 (TCMUL). The PC and SP are the first two addresses
+ * of that vector.  So to boot M4, the A core must build the M4's reset
+ * vector with getting the PC and SP from image and filling them to
+ * TCMUL. When M4 is kicked, it will load the PC and SP by itself.
+ * The TCMUL is mapped to (M4_BOOTROM_BASE_ADDR) at A core side for
+ * accessing the M4 TCMUL.
+ */
+int do_bootaux(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	ulong addr;
+	int ret, up;
+
+	if (argc < 2)
+		return CMD_RET_USAGE;
+
+	up = arch_auxiliary_core_check_up(0);
+	if (up) {
+		printf("## Auxiliary core is already up\n");
+		return CMD_RET_SUCCESS;
+	}
+
+	addr = simple_strtoul(argv[1], NULL, 16);
+
+	printf("## Starting auxiliary core at 0x%08lX ...\n", addr);
+
+	ret = arch_auxiliary_core_up(0, addr);
+	if (ret)
+		return CMD_RET_FAILURE;
+
+	return CMD_RET_SUCCESS;
+}
+
+U_BOOT_CMD(
+	bootaux, CONFIG_SYS_MAXARGS, 1,	do_bootaux,
+	"Start auxiliary core",
+	""
+);