feat: add SBI interface with ecall and timer functions for RISC-V architecture

1 files changed, 39 insertions, 0 deletions

diff --git a/na/arch/riscv/include/arch/sbi.h b/na/arch/riscv/include/arch/sbi.h
new file mode 100644
index 0000000..b65c37e
--- /dev/null
+++ b/na/arch/riscv/include/arch/sbi.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+#pragma once
+
+#include <lume/types.h>
+
+namespace arch::sbi {
+
+struct sbiret {
+    long error;
+    long value;
+};
+
+static inline sbiret sbi_ecall(int ext, int fid, uint64 arg0, uint64 arg1, uint64 arg2, uint64 arg3, uint64 arg4, uint64 arg5) {
+    sbiret ret;
+    register uint64 a0 asm("a0") = arg0;
+    register uint64 a1 asm("a1") = arg1;
+    register uint64 a2 asm("a2") = arg2;
+    register uint64 a3 asm("a3") = arg3;
+    register uint64 a4 asm("a4") = arg4;
+    register uint64 a5 asm("a5") = arg5;
+    register uint64 a6 asm("a6") = fid;
+    register uint64 a7 asm("a7") = ext;
+    __asm__ volatile("ecall"
+                     : "+r"(a0), "=r"(a1)
+                     : "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(a6), "r"(a7)
+                     : "memory");
+    ret.error = static_cast<long>(a0);
+    ret.value = static_cast<long>(a1);
+    return ret;
+}
+
+static inline void set_timer(uint64 stime_value) {
+    // Standard SBI TIME Extension (EID 0x54494D45)
+    sbi_ecall(0x54494D45, 0, stime_value, 0, 0, 0, 0, 0);
+}
+
+} // namespace arch::sbi