[PATCH v2 3/4] mkimage: sunxi_egon: add support for riscv

[Icenowy Zheng]

There's now a sun20i family in sunxi, which uses RISC-V CPU.

Add support for making eGON.BT0 image for RISC-V.

Signed-off-by: Icenowy Zheng <icen...@aosc.io>
---
Changes in v2:
- Removed changes that should belong to the previous patch in v1.

 tools/sunxi_egon.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/sunxi_egon.c b/tools/sunxi_egon.c
index 062c9bc151..836e99a6e6 100644
--- a/tools/sunxi_egon.c
+++ b/tools/sunxi_egon.c
@@ -29,6 +29,7 @@ static int egon_check_params(struct image_tool_params *params)
         */
        switch (arch) {
        case IH_ARCH_ARM:
+       case IH_ARCH_RISCV:
                break;
        default:
                return EXIT_FAILURE;
@@ -60,6 +61,10 @@ static int egon_verify_header(unsigned char *ptr, int 
image_size,
                if ((le32_to_cpu(header->b_instruction) & 0xff000000) != 
0xea000000)
                        return EXIT_FAILURE;
                break;
+       case IH_ARCH_RISCV:
+               if ((le32_to_cpu(header->b_instruction) & 0x00000fff) != 
0x0000006f)
+                       return EXIT_FAILURE;
+               break;
        default:
                return EXIT_FAILURE; /* Unknown architecture */
        }
@@ -128,6 +133,24 @@ static void egon_set_header(void *buf, struct stat *sbuf, 
int infd,
                value = 0xea000000 | (sizeof(struct boot_file_head) / 4 - 2);
                header->b_instruction = cpu_to_le32(value);
                break;
+       case IH_ARCH_RISCV:
+               /*
+                * Generate a RISC-V JAL instruction with rd=x0
+                * (pseudo instruction J, jump without side effects).
+                *
+                * The following weird bit operation maps imm[20]
+                * to inst[31], imm[10:1] to inst[30:21],
+                * imm[11] to inst[20], imm[19:12] to inst[19:12],
+                * and imm[0] is dropped (because 1-byte RISC-V instruction
+                * is not allowed).
+                */
+               value = 0x0000006f |
+                       ((sizeof(struct boot_file_head) & 0x00100000) << 11) |
+                       ((sizeof(struct boot_file_head) & 0x000007fe) << 20) |
+                       ((sizeof(struct boot_file_head) & 0x00000800) << 9) |
+                       ((sizeof(struct boot_file_head) & 0x000ff000) << 0);
+               header->b_instruction = cpu_to_le32(value);
+               break;
        }
 
        memcpy(header->magic, BOOT0_MAGIC, sizeof(header->magic));
-- 
2.30.2