[U-Boot] [PATCH v4 27/28] riscv: qemu: detect and boot the kernel passed by QEMU

[Lukas Auer]

QEMU embeds the location of the kernel image in the device tree. Store
this address in the environment as variable kernel_start. It is used in
the board-local distro boot command QEMU to boot the kernel with the
U-Boot device tree. The QEMU boot command is added as the first boot
target device.

Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
Reviewed-by: Alexander Graf <agraf at suse.de>
---

Changes in v4: None
Changes in v3:
- Adapt code and commit message to distro boot
- Replace printf with debug
- Clarify debug messages if no chosen node is found

Changes in v2:
- Rebase onto u-boot-dm/next
- Boot Linux with the device tree provided by the prior boot stage

 board/emulation/qemu-riscv/Kconfig      |  1 +
 board/emulation/qemu-riscv/qemu-riscv.c | 29 +++++++++++++++++++++++++
 include/configs/qemu-riscv.h            | 10 +++++++++
 3 files changed, 40 insertions(+)

diff --git a/board/emulation/qemu-riscv/Kconfig b/board/emulation/qemu-riscv/Kconfig
index 37a80db6a9..be5839b7db 100644
--- a/board/emulation/qemu-riscv/Kconfig
+++ b/board/emulation/qemu-riscv/Kconfig
@@ -29,5 +29,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	imply CMD_EXT2
 	imply CMD_EXT4
 	imply CMD_FAT
+	imply BOARD_LATE_INIT
 
 endif
diff --git a/board/emulation/qemu-riscv/qemu-riscv.c b/board/emulation/qemu-riscv/qemu-riscv.c
index 2ce093e19a..587f2c4909 100644
--- a/board/emulation/qemu-riscv/qemu-riscv.c
+++ b/board/emulation/qemu-riscv/qemu-riscv.c
@@ -19,3 +19,32 @@ int board_init(void)
 
 	return 0;
 }
+
+int board_late_init(void)
+{
+	ulong kernel_start;
+	ofnode chosen_node;
+	int ret;
+
+	chosen_node = ofnode_path("/chosen");
+	if (!ofnode_valid(chosen_node)) {
+		debug("No chosen node found, can't get kernel start address\n");
+		return 0;
+	}
+
+#ifdef CONFIG_ARCH_RV64I
+	ret = ofnode_read_u64(chosen_node, "riscv,kernel-start",
+			      (u64 *)&kernel_start);
+#else
+	ret = ofnode_read_u32(chosen_node, "riscv,kernel-start",
+			      (u32 *)&kernel_start);
+#endif
+	if (ret) {
+		debug("Can't find kernel start address in device tree\n");
+		return 0;
+	}
+
+	env_set_hex("kernel_start", kernel_start);
+
+	return 0;
+}
diff --git a/include/configs/qemu-riscv.h b/include/configs/qemu-riscv.h
index 66d61bd896..b29d155d09 100644
--- a/include/configs/qemu-riscv.h
+++ b/include/configs/qemu-riscv.h
@@ -21,11 +21,21 @@
 #define CONFIG_ENV_SIZE			SZ_4K
 
 #define BOOT_TARGET_DEVICES(func) \
+	func(QEMU, qemu, na) \
 	func(VIRTIO, virtio, 0) \
 	func(DHCP, dhcp, na)
 
 #include <config_distro_bootcmd.h>
 
+#define BOOTENV_DEV_QEMU(devtypeu, devtypel, instance) \
+	"bootcmd_qemu=" \
+		"if env exists kernel_start; then " \
+			"bootm ${kernel_start} - ${fdtcontroladdr};" \
+		"fi;\0"
+
+#define BOOTENV_DEV_NAME_QEMU(devtypeu, devtypel, instance) \
+	"qemu "
+
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"fdt_high=0xffffffffffffffff\0" \
 	"initrd_high=0xffffffffffffffff\0" \
-- 
2.17.2