Add `boot` command to opentitantool

- Add a `boot` command, which sets pin strapping to the `RUN` config,
  and toggles reset. This is intended to work around Nexus having
  pull-ups on the bootstrap lines, which means someone needs to drive
  the SW_STRAP pins low during reset for a "normal" boot.

Change-Id: I97b6a3df1b43713328e22c2520de17bd212d77e7

sw/host/opentitanlib/src/app/config/nexus.json

diff --git a/sw/host/opentitanlib/src/app/config/nexus.json b/sw/host/opentitanlib/src/app/config/nexus.json
index e34a640..70235c7 100644
--- a/sw/host/opentitanlib/src/app/config/nexus.json
+++ b/sw/host/opentitanlib/src/app/config/nexus.json
@@ -53,6 +53,27 @@
           "level": false
         }
       ]
+    },
+    {
+      "name": "RUN",
+      "pins": [
+        {
+          "name": "RESET",
+          "level": true
+        },
+        {
+          "name": "SW_STRAP0",
+          "level": false
+        },
+        {
+          "name": "SW_STRAP1",
+          "level": false
+        },
+        {
+          "name": "SW_STRAP2",
+          "level": false
+        }
+      ]
     }
   ],
   "spi": [

sw/host/opentitantool/BUILD

diff --git a/sw/host/opentitantool/BUILD b/sw/host/opentitantool/BUILD
index 599f1e2..d0918ae 100644
--- a/sw/host/opentitantool/BUILD
+++ b/sw/host/opentitantool/BUILD
@@ -10,6 +10,7 @@
 rust_binary(
     name = "opentitantool",
     srcs = [
+        "src/command/boot.rs",
         "src/command/bootstrap.rs",
         "src/command/clear_bitstream.rs",
         "src/command/console.rs",

sw/host/opentitantool/src/command/boot.rs

diff --git a/sw/host/opentitantool/src/command/boot.rs b/sw/host/opentitantool/src/command/boot.rs
new file mode 100644
index 0000000..d26879d
--- /dev/null
+++ b/sw/host/opentitantool/src/command/boot.rs
@@ -0,0 +1,34 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+use anyhow::Result;
+use serde_annotate::Annotate;
+use std::any::Any;
+use std::time::Duration;
+use structopt::StructOpt;
+
+use opentitanlib::app::TransportWrapper;
+use opentitanlib::app::command::CommandDispatch;
+
+/// Boot the target device.
+#[derive(Debug, StructOpt)]
+pub struct BootCommand {
+}
+
+impl CommandDispatch for BootCommand {
+    fn run(
+        &self,
+        _context: &dyn Any,
+        transport: &TransportWrapper,
+    ) -> Result<Option<Box<dyn Annotate>>> {
+        let reset_pin = transport.gpio_pin("RESET")?;
+        transport.apply_pin_strapping("RUN")?;
+        // Active-low RESET
+        reset_pin.write(true)?;
+        reset_pin.write(false)?;
+        reset_pin.write(true)?;
+        std::thread::sleep(Duration::from_millis(1000));
+        Ok(None)
+    }
+}

sw/host/opentitantool/src/command/mod.rs

diff --git a/sw/host/opentitantool/src/command/mod.rs b/sw/host/opentitantool/src/command/mod.rs
index 3e8c715..2f88e7f 100644
--- a/sw/host/opentitantool/src/command/mod.rs
+++ b/sw/host/opentitantool/src/command/mod.rs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0, see LICENSE for details.
 // SPDX-License-Identifier: Apache-2.0
 
+pub mod boot;
 pub mod bootstrap;
 pub mod clear_bitstream;
 pub mod console;

sw/host/opentitantool/src/main.rs

diff --git a/sw/host/opentitantool/src/main.rs b/sw/host/opentitantool/src/main.rs
index 4515a83..4c2f1f6 100644
--- a/sw/host/opentitantool/src/main.rs
+++ b/sw/host/opentitantool/src/main.rs
@@ -25,6 +25,7 @@
 #[allow(clippy::large_enum_variant)]
 #[derive(Debug, StructOpt, CommandDispatch)]
 enum RootCommandHierarchy {
+    Boot(command::boot::BootCommand),
     // Not flattened because `Bootstrap` is a leaf command.
     Bootstrap(command::bootstrap::BootstrapCommand),
     // Not flattened because `Console` is a leaf command.