I2C device tree descriptions in TOML (#36)

This is the Humility side of the Hubris I2C TOML work as described
in oxidecomputer/hubris#238.

.rustfmt.toml

@@ -1,2 +1,3 @@
 max_width = 80
 use_small_heuristics = "max"
+wrap_comments = true

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "humility"
-version = "0.4.1"
+version = "0.5.0"
 authors = ["Bryan Cantrill <bryan@oxide.computer>"]
 edition = "2018"
 
@@ -47,4 +47,4 @@ indicatif = "0.15"
 colored = "2.0.0"
 postcard = "0.7.0"
 itertools = "0.10.1"
-indexmap = "1.7"
+indexmap = { version = "1.7", features = ["serde-1"] }

src/cmd/diagnose.rs

@@ -127,7 +127,8 @@ fn diagnose(
 
     println!("Snapshot taken, {} tasks in application.", tasks_0.len());
 
-    let narrow_generations = matches!(tasks_0[0].generation, GenOrRestartCount::Gen(_));
+    let narrow_generations =
+        matches!(tasks_0[0].generation, GenOrRestartCount::Gen(_));
 
     if narrow_generations {
         println!(
@@ -281,7 +282,11 @@ fn diagnose(
             // Estimate restart rate.
             if let Some(dt) = delta_ticks {
                 let f = f64::from(count) / dt as f64;
-                println!("- (this is {:.03} restarts/tick, or {:.03}/s)", f, 1000. * f);
+                println!(
+                    "- (this is {:.03} restarts/tick, or {:.03}/s)",
+                    f,
+                    1000. * f
+                );
             }
 
             // Report previous or current faults.

src/cmd/etm.rs

@@ -190,11 +190,11 @@ fn etmcmd_enable(
     trace!("{:#x?}", TPIU_ACPR::read(core)?);
 
     /*
-     * We are now ready to enable ETM.  There are a bunch of steps involved in
-     * this, but we need to first write to the ETMCR to indicate that we are
-     * programming it.  Once done writing to the ETM control registers, we
-     * need to write to ETMCR again to indicate that we are done programming
-     * it.
+     * We are now ready to enable ETM.  There are a bunch of steps involved
+     * in this, but we need to first write to the ETMCR to indicate that
+     * we are programming it.  Once done writing to the ETM control
+     * registers, we need to write to ETMCR again to indicate that we are
+     * done programming it.
      */
     trace!("{:#x?}", ETMCR::read(core)?);
     let mut etmcr = ETMCR::read(core)?;