firmware: increase post-boot UART speed to 921600.

artiq/firmware/libboard/lib.rs

@@ -11,6 +11,7 @@ include!(concat!(env!("BUILDINC_DIRECTORY"), "/generated/csr.rs"));
 pub mod spr;
 pub mod irq;
 pub mod clock;
+pub mod uart;
 
 #[cfg(has_i2c)]
 pub mod i2c;

artiq/firmware/libboard/uart.rs

@@ -0,0 +1,8 @@
+use csr;
+
+pub fn set_speed(rate: u32) {
+    unsafe {
+        let tuning_word = (rate as u64) * (1 << 32) / (csr::CONFIG_CLOCK_FREQUENCY as u64);
+        csr::uart_phy::tuning_word_write(tuning_word as u32);
+    }
+}

artiq/firmware/runtime/lib.rs

@@ -103,6 +103,7 @@ pub unsafe extern fn rust_main() {
     static mut LOG_BUFFER: [u8; 65536] = [0; 65536];
     BufferLogger::new(&mut LOG_BUFFER[..])
                  .register(move || {
+        board::uart::set_speed(921600);
         board::clock::init();
         info!("ARTIQ runtime starting...");
         info!("software version {}", GIT_COMMIT);

artiq/frontend/artiq_devtool.py

@@ -66,11 +66,11 @@ def main():
     tmp = "artiq" + "".join([rng.choice("ABCDEFGHIJKLMNOPQRSTUVWXYZ") for _ in range(6)])
     env = "bash -c 'export PATH=$HOME/miniconda/bin:$PATH; exec $0 $*' "
 
-    def run_command(cmd):
+    def run_command(cmd, **kws):
         logger.info("Executing {}".format(cmd))
         chan = get_ssh().get_transport().open_session()
         chan.set_combine_stderr(True)
-        chan.exec_command(cmd.format(tmp=tmp, env=env, serial=args.serial, ip=args.ip))
+        chan.exec_command(cmd.format(tmp=tmp, env=env, serial=args.serial, ip=args.ip, **kws))
         return chan.makefile()
 
     def drain(chan):
@@ -151,7 +151,7 @@ def main():
 
             logger.info("Connecting to device")
             flterm = run_command(
-                "{env} python3 flterm.py {serial} --output-only")
+                "{env} python3 flterm.py {serial} --speed 921600 --output-only")
             drain(flterm)
 
         else: