support baud rate switching with flash stubs

Co-authored-by: Timothy Mertz <[email protected]>

Author: ryankurte

espflash/src/command.rs

@@ -113,7 +113,10 @@ pub enum Command<'a> {
         spi_params: SpiAttachParams,
     },
     ChangeBaud {
-        speed: u32,
+        /// New baud rate
+        new_baud: u32,
+        /// Prior baud rate ('0' for ROM flasher)
+        prior_baud: u32,
     },
     FlashDeflateBegin {
         size: u32,
@@ -267,14 +270,14 @@ impl<'a> Command<'a> {
             Command::SpiAttach { spi_params } => {
                 write_basic(writer, &spi_params.encode(), 0)?;
             }
-            Command::ChangeBaud { speed } => {
+            Command::ChangeBaud { new_baud, prior_baud } => {
                 // length
                 writer.write_all(&(8u16.to_le_bytes()))?;
                 // checksum
                 writer.write_all(&(0u32.to_le_bytes()))?;
                 // data
-                writer.write_all(&speed.to_le_bytes())?;
-                writer.write_all(&0u32.to_le_bytes())?;
+                writer.write_all(&new_baud.to_le_bytes())?;
+                writer.write_all(&prior_baud.to_le_bytes())?;
             }
             Command::FlashDeflateBegin {
                 size,

espflash/src/flasher.rs

@@ -183,10 +183,16 @@ struct EntryParams {
 }
 
 pub struct Flasher {
+    /// Connection for flash operations
     connection: Connection,
+    /// Chip ID
     chip: Chip,
+    /// Flash size, loaded from SPI flash
     flash_size: FlashSize,
+    /// Configuration for SPI attached flash (0 to use fused values)
     spi_params: SpiAttachParams,
+    /// Indicate RAM stub loader is in use
+    use_stub: bool,
 }
 
 impl Flasher {
@@ -211,6 +217,7 @@ impl Flasher {
             chip,
             flash_size: FlashSize::Flash4Mb,
             spi_params: SpiAttachParams::default(),
+            use_stub,
         };
 
         // Load flash stub if enabled
@@ -590,9 +597,16 @@ impl Flasher {
     }
 
     pub fn change_baud(&mut self, speed: u32) -> Result<(), Error> {
+        debug!("Change baud to: {}", speed);
+
+        let prior_baud = match self.use_stub {
+            true => self.connection.get_baud()?,
+            false => 0,
+        };
+
         self.connection
             .with_timeout(CommandType::ChangeBaud.timeout(), |connection| {
-                connection.command(Command::ChangeBaud { speed })
+                connection.command(Command::ChangeBaud { new_baud: speed, prior_baud })
             })?;
         self.connection.set_baud(speed)?;
         std::thread::sleep(Duration::from_secs_f32(0.05));