From 8497f98de244f0f8800df78d6e83a2fb886016bf Mon Sep 17 00:00:00 2001
From: huntc <huntchr@gmail.com>
Date: Wed, 4 Jan 2023 11:07:07 +1100
Subject: [PATCH] Provides a means of obtaining the current WDT config

Obtaining the current WDT config is important so that we do not have to duplication configuration around the place. A constructor method has been introduced that returns WDT config in accordance with how the register is presently configured. The bootloader example has also been updated to show the watchdog can be obtained and used.
---
 embassy-nrf/src/wdt.rs                     | 24 ++++++++++++++++++++++
 examples/boot/application/nrf/src/bin/a.rs | 18 ++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/embassy-nrf/src/wdt.rs b/embassy-nrf/src/wdt.rs
index 8760aa30..330ca98b 100644
--- a/embassy-nrf/src/wdt.rs
+++ b/embassy-nrf/src/wdt.rs
@@ -23,6 +23,30 @@ pub struct Config {
     pub run_during_debug_halt: bool,
 }
 
+impl Config {
+    /// Create a config structure from the current configuration of the WDT
+    /// peripheral.
+    pub fn try_new(_wdt: &peripherals::WDT) -> Option<Self> {
+        let r = unsafe { &*WDT::ptr() };
+
+        #[cfg(not(feature = "_nrf9160"))]
+        let runstatus = r.runstatus.read().runstatus().bit();
+        #[cfg(feature = "_nrf9160")]
+        let runstatus = r.runstatus.read().runstatuswdt().bit();
+
+        if runstatus {
+            let config = r.config.read();
+            Some(Self {
+                timeout_ticks: r.crv.read().bits(),
+                run_during_sleep: config.sleep().bit(),
+                run_during_debug_halt: config.halt().bit(),
+            })
+        } else {
+            None
+        }
+    }
+}
+
 impl Default for Config {
     fn default() -> Self {
         Self {
diff --git a/examples/boot/application/nrf/src/bin/a.rs b/examples/boot/application/nrf/src/bin/a.rs
index 7a404a91..83191f38 100644
--- a/examples/boot/application/nrf/src/bin/a.rs
+++ b/examples/boot/application/nrf/src/bin/a.rs
@@ -8,6 +8,7 @@ use embassy_embedded_hal::adapter::BlockingAsync;
 use embassy_executor::Spawner;
 use embassy_nrf::gpio::{Input, Level, Output, OutputDrive, Pull};
 use embassy_nrf::nvmc::Nvmc;
+use embassy_nrf::wdt::{self, Watchdog};
 use panic_reset as _;
 
 static APP_B: &[u8] = include_bytes!("../../b.bin");
@@ -20,6 +21,23 @@ async fn main(_spawner: Spawner) {
     //let mut led = Output::new(p.P1_10, Level::Low, OutputDrive::Standard);
     //let mut button = Input::new(p.P1_02, Pull::Up);
 
+    // The following code block illustrates how to obtain a watchdog that is configured
+    // as per the existing watchdog. Ordinarily, we'd use the handle returned to "pet" the
+    // watchdog periodically. If we don't, and we're not going to for this example, then
+    // the watchdog will cause the device to reset as per its configured timeout in the bootloader.
+    // This helps is avoid a situation where new firmware might be bad and block our executor.
+    // If firmware is bad in this way then the bootloader will revert to any previous version.
+    let wdt_config = wdt::Config::try_new(&p.WDT).unwrap();
+    let (_wdt, [_wdt_handle]) = match Watchdog::try_new(p.WDT, wdt_config) {
+        Ok(x) => x,
+        Err(_) => {
+            // Watchdog already active with the wrong number of handles, waiting for it to timeout...
+            loop {
+                cortex_m::asm::wfe();
+            }
+        }
+    };
+
     let nvmc = Nvmc::new(p.NVMC);
     let mut nvmc = BlockingAsync::new(nvmc);