rp2xxx: Unique board identifier (#910)

Author: ianic

examples/raspberrypi/rp2xxx/build.zig

@@ -18,7 +18,6 @@ pub fn build(b: *std.Build) void {
         // RaspberryPi Boards:
         .{ .target = raspberrypi.pico, .name = "pico_board_blinky", .file = "src/board_blinky.zig" },
         .{ .target = raspberrypi.pico, .name = "pico_flash-program", .file = "src/rp2040_only/flash_program.zig" },
-        .{ .target = raspberrypi.pico, .name = "pico_flash-id", .file = "src/rp2040_only/flash_id.zig" },
         .{ .target = raspberrypi.pico, .name = "pico_random", .file = "src/rp2040_only/random.zig" },
         .{ .target = raspberrypi.pico, .name = "pico_rtc", .file = "src/rp2040_only/rtc.zig" },
         .{ .target = raspberrypi.pico, .name = "pico_multicore", .file = "src/blinky_core1.zig" },
@@ -103,6 +102,7 @@ pub fn build(b: *std.Build) void {
         .{ .name = "net-udp", .file = "src/net/udp.zig" },
         .{ .name = "net-tcp_client", .file = "src/net/tcp_client.zig" },
         .{ .name = "net-tcp_server", .file = "src/net/tcp_server.zig" },
+        .{ .name = "board-id", .file = "src/board_id.zig" },
     };
 
     var available_examples: std.array_list.Managed(Example) = .init(b.allocator);

…rypi/rp2xxx/src/rp2040_only/flash_id.zig …ples/raspberrypi/rp2xxx/src/board_id.zigexamples/raspberrypi/rp2xxx/src/rp2040_only/flash_id.zig renamed to examples/raspberrypi/rp2xxx/src/board_id.zig examples/raspberrypi/rp2xxx/src/rp2040_only/flash_id.zig renamed to examples/raspberrypi/rp2xxx/src/board_id.zig

@@ -4,7 +4,6 @@ const microzig = @import("microzig");
 const rp2xxx = microzig.hal;
 const time = rp2xxx.time;
 const gpio = rp2xxx.gpio;
-const flash = rp2xxx.flash;
 
 const uart = rp2xxx.uart.instance.num(0);
 const uart_tx_pin = gpio.num(0);
@@ -15,10 +14,11 @@ pub fn panic(message: []const u8, _: ?*std.builtin.StackTrace, _: ?usize) noretu
     while (true) {}
 }
 
-pub const std_options = struct {
-    pub const log_level = .debug;
-    pub const logFn = rp2xxx.uart.log;
+pub const microzig_options = microzig.Options{
+    .log_level = .debug,
+    .logFn = rp2xxx.uart.log,
 };
+const log = std.log.scoped(.main);
 
 pub fn main() !void {
     // init uart logging
@@ -29,9 +29,7 @@ pub fn main() !void {
     rp2xxx.uart.init_logger(uart);
 
     while (true) {
-        const serial_number = flash.id();
-        const hex_serial_number = std.fmt.bytesToHex(&serial_number, .lower);
-        std.log.info("serial number: {s}", .{hex_serial_number});
+        log.info("unique board id: {x}", .{rp2xxx.get_board_id()});
         time.sleep_ms(1000);
     }
 }

port/raspberrypi/rp2xxx/src/hal.zig

@@ -1,5 +1,4 @@
 const builtin = @import("builtin");
-const std = @import("std");
 const microzig = @import("microzig");
 const SIO = microzig.chip.peripherals.SIO;
 
@@ -144,6 +143,24 @@ pub fn get_cpu_id() u32 {
     return SIO.CPUID.read().CPUID;
 }
 
+var board_id: ?[8]u8 = null;
+
+/// Unique board identifier.
+/// On an RP2040-based board, the unique identifier is retrieved from the
+/// external NOR flash device
+/// On an RP2350-based board, the unique identifier is retrieved from OTP
+/// memory.
+pub fn get_board_id() [8]u8 {
+    if (board_id) |b| {
+        return b;
+    }
+    board_id = switch (compatibility.chip) {
+        .RP2040 => flash.id(),
+        .RP2350 => rom.get_board_id(),
+    };
+    return board_id.?;
+}
+
 test "hal tests" {
     _ = pio;
     _ = usb;

port/raspberrypi/rp2xxx/src/hal/rom.zig

@@ -6,11 +6,8 @@
 //! that would otherwise have to take up space in most user binaries.
 
 const std = @import("std");
-const microzig = @import("microzig");
 const compatibility = @import("compatibility.zig");
-const arch = compatibility.arch;
 const chip = compatibility.chip;
-const options = microzig.options.hal;
 
 /// Returns the ROM version number.
 pub inline fn get_version_number() u8 {
@@ -213,3 +210,24 @@ pub fn reset_to_usb_boot() void {
         },
     }
 }
+
+pub fn get_sys_info(out_buffer: [*]u32, out_buffer_word_size: u32, flags: u32) void {
+    switch (chip) {
+        .RP2040 => @compileError("not supported on this chip"),
+        .RP2350 => {
+            const f: *const signatures.get_sys_info = @ptrCast(@alignCast(lookup_function(.get_sys_info)));
+            const rc = f(out_buffer, out_buffer_word_size, flags);
+            std.debug.assert(rc == 4);
+        },
+    }
+}
+
+pub fn get_board_id() [8]u8 {
+    var out: [9]u32 = @splat(0);
+    get_sys_info(&out, out.len, 0x001);
+    var buf: [8]u8 = undefined;
+    for (std.mem.asBytes(out[2..])[0..8], 1..) |b, i| {
+        buf[8 - i] = b;
+    }
+    return buf;
+}