logging: Use UART directly if available

Some SBIs don't implement the Debug Console extension. Using the UART is one solution, supporting the SBI Legacy extension might work too if it exists.

1 files changed, 26 insertions, 25 deletions

diff --git a/src/main.zig b/src/main.zig
index d727d6f..540e8f8 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -4,7 +4,7 @@
 
 const std = @import("std");
 
-const debug_console = @import("sbi/debug_console.zig");
+const Console = @import("Console.zig");
 const fdt = @import("fdt.zig");
 const instructions = @import("instructions.zig");
 const interrupts = @import("interrupts.zig");
@@ -25,7 +25,8 @@ pub fn panic(msg: []const u8, error_return_trace: ?*std.builtin.StackTrace, ret_
 
     @setCold(true);
 
-    const w = debug_console.writer() catch while (true) asm volatile ("wfi");
+    const console = Console.autoChoose() orelse while (true) asm volatile ("wfi");
+    const w = console.writer();
 
     w.print("\r\n", .{}) catch while (true) asm volatile ("wfi");
     w.print("= !! ========== !! =\r\n", .{}) catch while (true) asm volatile ("wfi");
@@ -49,20 +50,11 @@ export fn _start() callconv(.Naked) noreturn {
 }
 
 fn kmain(hart_id: usize, fdt_blob: *fdt.RawHeader) noreturn {
-    const w = debug_console.writer() catch while (true) {};
-    w.print("Kernel init\r\n", .{}) catch while (true) {};
-
-    run(hart_id, fdt_blob, w) catch |err| std.debug.panic("Hart {d}: {any}", .{ hart_id, err });
+    run(hart_id, fdt_blob) catch |err| std.debug.panic("Hart {d}: {any}", .{ hart_id, err });
 }
 
-fn run(hart_id: usize, fdt_blob: *fdt.RawHeader, w: debug_console.Writer) !noreturn {
-    try w.print("\r\n", .{});
-
-    try w.print("Hart        : {d}\r\n", .{hart_id});
-    try w.print("FDT address : 0x{x:0>8}\r\n", .{@intFromPtr(fdt_blob)});
-
+fn run(hart_id: usize, fdt_blob: *fdt.RawHeader) !noreturn {
     if (hart_id > ~@as(u16, 0)) return Error.HartIdOutOfRange;
-    if (@intFromPtr(fdt_blob) < 0xf000000) return Error.SuspiciousFdtAddr;
 
     const dt_header = try fdt.Header.parse(fdt_blob);
 
@@ -70,6 +62,26 @@ fn run(hart_id: usize, fdt_blob: *fdt.RawHeader, w: debug_console.Writer) !noret
 
     const kmem: *paging.Table = @alignCast(@ptrCast(try paging.zeroedAlloc(1)));
 
+    try kmem.mapKernel();
+    try kmem.mapFdt(&dt_header);
+
+    var chunk_allocator = try mem.ChunkAllocator(.{ .auto_merge_free = true }).init(128);
+    const allocator = chunk_allocator.allocator();
+
+    fdt.default = try dt_header.parseTree(allocator);
+
+    try Console.init(kmem, &fdt.default, allocator);
+
+    const console = Console.autoChoose() orelse while (true) asm volatile ("wfi");
+    const w = console.writer();
+
+    try w.print("\r\n", .{});
+    try w.print("Console init\r\n", .{});
+    try w.print("\r\n", .{});
+
+    try w.print("Hart        : {d}\r\n", .{hart_id});
+    try w.print("FDT address : 0x{x:0>8}\r\n", .{@intFromPtr(fdt_blob)});
+
     try w.print("\r\n", .{});
     try w.print("===================== Kernel Page Table =====================\r\n", .{});
     try w.print("MMIO:        0x{x:0>8} - 0x{x:0>8} -> identity mapped (rw-)\r\n", .{ paging.mmio_start, paging.mmio_end });
@@ -87,10 +99,8 @@ fn run(hart_id: usize, fdt_blob: *fdt.RawHeader, w: debug_console.Writer) !noret
     try w.print("=============================================================\r\n", .{});
     try w.print("\r\n", .{});
 
-    try kmem.mapKernel();
-    try kmem.mapFdt(&dt_header);
-
     instructions.setSatp(kmem.satp(0));
+
     try w.print("Paging      : Sv39\r\n", .{});
 
     interrupts.init();
@@ -99,15 +109,6 @@ fn run(hart_id: usize, fdt_blob: *fdt.RawHeader, w: debug_console.Writer) !noret
 
     try w.print("\r\n", .{});
 
-    var chunk_allocator = try mem.ChunkAllocator(.{ .auto_merge_free = true }).init(64);
-    const allocator = chunk_allocator.allocator();
-
-    try w.print("Parse FDT\r\n", .{});
-
-    fdt.default = try dt_header.parseTree(allocator);
-
-    try w.print("\r\n", .{});
-
     try w.print("Timer       : {d} Hz\r\n", .{1 / (@as(f64, process.schedule_interval_millis) / 1000)});
 
     try plic.init(&fdt.default, allocator);