Only read value types from efuses (#2259)

* Only read value types from efuses

* Changelog

* Clean up remaining bool reads

esp-hal/CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Make `DmaDescriptor` methods public (#2237)
 - Added a way to configure watchdogs in `esp_hal::init` (#2180)
 - Implement `embedded_hal_async::delay::DelayNs` for `TIMGx` timers (#2084)
+- Added `Efuse::read_bit` (#2259)
 
 ### Changed
 
@@ -78,6 +79,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - TWAI on ESP32 (#2207)
 - TWAI should no longer panic when receiving a non-compliant frame (#2255)
 - OneShotTimer: fixed `delay_nanos` behaviour (#2256)
+- Fixed unsoundness around `Efuse` (#2259)
 
 ### Removed
 

esp-hal/MIGRATING-0.20.md

@@ -255,3 +255,7 @@ Diff of the `psram_quad.rs` example
 ...
 
 ```
+
+## eFuse
+
+Calling `Efuse::read_field_le::<bool>()` no longer compiles. Use `Efuse::read_bit()` instead.

esp-hal/src/soc/efuse_field.rs

@@ -1,3 +1,5 @@
+use bytemuck::AnyBitPattern;
+
 use crate::soc::efuse::{Efuse, EfuseBlock};
 
 /// The bit field for get access to efuse data
@@ -21,7 +23,7 @@ impl EfuseField {
 impl Efuse {
     /// Read field value in a little-endian order
     #[inline(always)]
-    pub fn read_field_le<T: Sized + 'static>(field: EfuseField) -> T {
+    pub fn read_field_le<T: AnyBitPattern>(field: EfuseField) -> T {
         let mut output = core::mem::MaybeUninit::<T>::uninit();
         // represent output value as a bytes slice
         let mut bytes = unsafe {
@@ -89,7 +91,7 @@ impl Efuse {
 
     /// Read field value in a big-endian order
     #[inline(always)]
-    pub fn read_field_be<T: Sized + 'static>(field: EfuseField) -> T {
+    pub fn read_field_be<T: AnyBitPattern>(field: EfuseField) -> T {
         // read value in a little-endian order
         let mut output = Self::read_field_le::<T>(field);
         // represent output value as a byte slice
@@ -103,4 +105,13 @@ impl Efuse {
         bytes.reverse();
         output
     }
+
+    /// Read bit value.
+    ///
+    /// This function panics if the field's bit length is not equal to 1.
+    #[inline(always)]
+    pub fn read_bit(field: EfuseField) -> bool {
+        assert_eq!(field.bit_len, 1);
+        Self::read_field_le::<u8>(field) != 0
+    }
 }

esp-hal/src/soc/esp32/efuse/mod.rs

@@ -85,7 +85,7 @@ impl Efuse {
     /// CPU and application CPU), the application CPU is unavailable on
     /// some.
     pub fn get_core_count() -> u32 {
-        if Self::read_field_le::<bool>(DISABLE_APP_CPU) {
+        if Self::read_bit(DISABLE_APP_CPU) {
             1
         } else {
             2
@@ -97,8 +97,8 @@ impl Efuse {
     /// Note that the actual clock may be lower, depending on the current power
     /// configuration of the chip, clock source, and other settings.
     pub fn get_max_cpu_frequency() -> HertzU32 {
-        let has_rating = Self::read_field_le::<bool>(CHIP_CPU_FREQ_RATED);
-        let has_low_rating = Self::read_field_le::<bool>(CHIP_CPU_FREQ_LOW);
+        let has_rating = Self::read_bit(CHIP_CPU_FREQ_RATED);
+        let has_low_rating = Self::read_bit(CHIP_CPU_FREQ_LOW);
 
         if has_rating && has_low_rating {
             160.MHz()
@@ -109,7 +109,7 @@ impl Efuse {
 
     /// Returns the CHIP_VER_DIS_BT eFuse value.
     pub fn is_bluetooth_enabled() -> bool {
-        !Self::read_field_le::<bool>(DISABLE_BT)
+        !Self::read_bit(DISABLE_BT)
     }
 
     /// Returns the CHIP_VER_PKG eFuse value.

esp-hal/src/usb_serial_jtag.rs

@@ -291,7 +291,7 @@ where
 
             // On the esp32c3, and esp32s3 the USB_EXCHG_PINS efuse is bugged and
             // doesn't swap the pullups too, this works around that.
-            if Efuse::read_field_le(USB_EXCHG_PINS) {
+            if Efuse::read_bit(USB_EXCHG_PINS) {
                 USB_DEVICE::register_block().conf0().modify(|_, w| {
                     w.pad_pull_override()
                         .set_bit()