riscv: Add boot hartid to device tree

Linux booting protocol mandates that register "a0" contains the hartid.
However, U-Boot can not pass the hartid via a0 during standard UEFI
protocol. DT nodes are commonly used to pass such information to the OS.

Add a DT node under chosen node to indicate the boot hartid. EFI stub
in Linux kernel will parse this node and pass it to the real kernel
in "a0" before jumping to it.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c
index fad16901c5..87cadad501 100644
--- a/arch/riscv/lib/bootm.c
+++ b/arch/riscv/lib/bootm.c
@@ -28,6 +28,28 @@ __weak void board_quiesce_devices(void)
 
 int arch_fixup_fdt(void *blob)
 {
+#ifdef CONFIG_EFI_LOADER
+	int err;
+	u32 size;
+	int chosen_offset;
+
+	size = fdt_totalsize(blob);
+	err  = fdt_open_into(blob, blob, size + 32);
+	if (err < 0) {
+		printf("Device Tree can't be expanded to accommodate new node");
+		return err;
+	}
+	chosen_offset = fdt_path_offset(blob, "/chosen");
+	if (chosen_offset < 0) {
+		err = fdt_add_subnode(blob, 0, "chosen");
+		if (err < 0) {
+			printf("chosen node can not be added\n");
+			return err;
+		}
+	}
+	/* Overwrite the boot-hartid as U-Boot is the last stage BL */
+	fdt_setprop_u32(blob, chosen_offset, "boot-hartid", gd->arch.boot_hart);
+#endif
 	return 0;
 }