Pull config from the BIOS, or use the default.

Uses serde + postcard for serialisation.

Author: thejpster

Cargo.toml

@@ -19,8 +19,8 @@ debug = true
 codegen-units = 1
 opt-level = "s"
 
-[dependencies.neotron-common-bios]
-path = "./common"
-
-[dependencies.r0]
-version = "1.0"
+[dependencies]
+neotron-common-bios = { path = "./common" }
+r0 = "1.0"
+postcard = "0.5"
+serde = { version = "1.0", default-features = false }

common

@@ -12,6 +12,7 @@
 // Imports
 use core::fmt::Write;
 use neotron_common_bios as bios;
+use serde::{Deserialize, Serialize};
 
 // ===========================================================================
 // Global Variables
@@ -184,56 +185,53 @@ impl core::fmt::Write for SerialConsole {
     }
 }
 
-// ===========================================================================
-// Private functions
-// ===========================================================================
-
-/// Initialise our global variables - the BIOS will not have done this for us
-/// (as it doesn't know where they are).
-unsafe fn start_up_init() {
-    extern "C" {
-
-        // These symbols come from `link.x`
-        static mut __sbss: u32;
-        static mut __ebss: u32;
-
-        static mut __sdata: u32;
-        static mut __edata: u32;
-        static __sidata: u32;
-    }
-
-    r0::zero_bss(&mut __sbss, &mut __ebss);
-    r0::init_data(&mut __sdata, &mut __edata, &__sidata);
-}
-
+/// Represents our configuration information that we ask the BIOS to serialise
+#[derive(Debug, Serialize, Deserialize)]
 struct Config {
-    vga_console: bool,
-    serial_console: bool,
+    vga_console_on: bool,
+    serial_console_on: bool,
+    serial_baud: u32,
 }
 
 impl Config {
-    /// Create a new default Config object
-    ///
-    /// TODO: We should load from EEPROM / RTC SRAM here.
-    fn new() -> Config {
-        Config {
-            vga_console: true,
-            serial_console: true,
+    fn load() -> Result<Config, &'static str> {
+        if let Some(api) = unsafe { API } {
+            let mut buffer = [0u8; 64];
+            match (api.configuration_get)(bios::ApiBuffer::new(&mut buffer)) {
+                bios::Result::Ok(n) => {
+                    postcard::from_bytes(&buffer[0..n]).map_err(|_e| "Failed to parse config")
+                }
+                bios::Result::Err(_e) => Err("Failed to load config"),
+            }
+        } else {
+            Err("No API available?!")
+        }
+    }
+
+    fn save(&self) -> Result<(), &'static str> {
+        if let Some(api) = unsafe { API } {
+            let mut buffer = [0u8; 64];
+            let slice =
+                postcard::to_slice(self, &mut buffer).map_err(|_e| "Failed to parse config")?;
+            (api.configuration_set)(bios::ApiByteSlice::new(slice));
+            Ok(())
+        } else {
+            Err("No API available?!")
         }
     }
 
     /// Should this system use the VGA console?
     fn has_vga_console(&self) -> bool {
-        self.vga_console
+        self.vga_console_on
     }
 
     /// Should this system use the UART console?
     fn has_serial_console(&self) -> Option<(u8, bios::serial::Config)> {
-        if self.serial_console {
+        if self.serial_console_on {
             Some((
                 0,
                 bios::serial::Config {
-                    data_rate_bps: 115200,
+                    data_rate_bps: self.serial_baud,
                     data_bits: bios::serial::DataBits::Eight,
                     stop_bits: bios::serial::StopBits::One,
                     parity: bios::serial::Parity::None,
@@ -246,6 +244,38 @@ impl Config {
     }
 }
 
+impl core::default::Default for Config {
+    fn default() -> Config {
+        Config {
+            vga_console_on: true,
+            serial_console_on: false,
+            serial_baud: 115200,
+        }
+    }
+}
+
+// ===========================================================================
+// Private functions
+// ===========================================================================
+
+/// Initialise our global variables - the BIOS will not have done this for us
+/// (as it doesn't know where they are).
+unsafe fn start_up_init() {
+    extern "C" {
+
+        // These symbols come from `link.x`
+        static mut __sbss: u32;
+        static mut __ebss: u32;
+
+        static mut __sdata: u32;
+        static mut __edata: u32;
+        static __sidata: u32;
+    }
+
+    r0::zero_bss(&mut __sbss, &mut __ebss);
+    r0::init_data(&mut __sdata, &mut __edata, &__sidata);
+}
+
 // ===========================================================================
 // Public functions / impl for public types
 // ===========================================================================
@@ -258,7 +288,7 @@ extern "C" fn main(api: &'static bios::Api) -> ! {
         API = Some(api);
     }
 
-    let config = Config::new();
+    let config = Config::load().unwrap_or_else(|_| Config::default());
 
     if config.has_vga_console() {
         let mut addr: *mut u8 = core::ptr::null_mut();