feat: add preemptive scheduling, SBI timer support and FDT parser.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/kernel/sbi.cc b/src/kernel/sbi.cc
new file mode 100644
index 0000000..442d219
--- /dev/null
+++ b/src/kernel/sbi.cc
@@ -0,0 +1,34 @@
+#include "common/types.h"
+
+namespace SBI
+{
+    struct sbiret
+    {
+        long error;
+        long value;
+    };
+
+    struct sbiret sbi_call(int ext, int fid, uint64 arg0, uint64 arg1, uint64 arg2)
+    {
+        struct sbiret ret;
+        register uint64 a0 asm("a0") = arg0;
+        register uint64 a1 asm("a1") = arg1;
+        register uint64 a2 asm("a2") = arg2;
+        register uint64 a6 asm("a6") = fid;
+        register uint64 a7 asm("a7") = ext;
+
+        asm volatile(
+            "ecall"
+            : "=r"(a0), "=r"(a1)
+            : "r"(a0), "r"(a1), "r"(a2), "r"(a6), "r"(a7)
+            : "memory");
+        ret.error = a0;
+        ret.value = a1;
+        return ret;
+    }
+
+    void set_timer(uint64 stime_value)
+    {
+        sbi_call(0x54494D45, 0, stime_value, 0, 0);
+    }
+}
\ No newline at end of file