add timer_src_clk_sys feature to support running RP2350x timer at system clock frequency

Author: U007D

embassy-rp/Cargo.toml

@@ -42,7 +42,8 @@ critical-section-impl = ["critical-section/restore-state-u8"]
 unstable-pac = []
 
 ## Enable the timer for use with `embassy-time` with a 1MHz tick rate.
-time-driver = ["dep:embassy-time-driver", "embassy-time-driver?/tick-hz-1_000_000", "dep:embassy-time-queue-utils"]
+#time-driver = ["dep:embassy-time-driver", "embassy-time-driver?/tick-hz-1_000_000", "dep:embassy-time-queue-utils"]
+time-driver = ["dep:embassy-time-driver", "dep:embassy-time-queue-utils"]
 
 ## Enable ROM function cache. This will store the address of a ROM function when first used, improving performance of subsequent calls.
 rom-func-cache = []
@@ -122,7 +123,15 @@ _rp235x = ["rp-pac/rp235x"]
 rp235xa = ["_rp235x"]
 ## Configure the hal for use with the rp235xB
 rp235xb = ["_rp235x"]
-
+## Add a feature which configures `embassy-time-driver` with 150MHz `tick`s.  This is an indication
+## by the upstream crate that the RP2350's `TIMER`s are configured with the system clock as their
+## source (typically 150MHz), instead of the usual 1MHz.
+## Compilation flag checks in `lib.rs` ensure this feature is only used together with `_rp235x`
+timer-src-clk-sys = [
+    "dep:embassy-time-driver",
+    "embassy-time-driver?/tick-hz-150_000_000",
+    "dep:embassy-time-queue-utils",
+]
 # hack around cortex-m peripherals being wrong when running tests.
 _test = []
 

embassy-rp/src/lib.rs

@@ -6,6 +6,22 @@
 //! ## Feature flags
 #![doc = document_features::document_features!(feature_label = r#"<span class="stab portability"><code>{feature}</code></span>"#)]
 
+//! ## Compatible feature flags
+// `timer-src-clk-sys` only makes sense on RP235x silicon.
+#[cfg(all(
+    feature = "timer-src-clk-sys",
+    not(feature = "_rp235x"),
+))]
+compile_error!(
+    "`embassy-rp` feature `timer-src-clk-sys` requires an `rp235x` feature (either `rp235xa` or \
+    `rp235xb`) to be enabled."
+);
+
+// // Prevent users from selecting both timer drivers (although this condition causes a redefinition
+// // error in our deps before this code can halt the compilation with an explanation...)
+// #[cfg(all(feature = "timer-src-clk-sys", feature = "time-driver"))]
+// compile_error!("Enable only one of `time-driver` or `timer-src-clk-sys`.");
+
 // This mod MUST go first, so that the others see its macros.
 pub(crate) mod fmt;