From cce522a46389ec5695ae6e828c2a727bf19b9001 Mon Sep 17 00:00:00 2001
From: bjoernQ <bjoern.quentin@mobile-j.de>
Date: Tue, 7 Nov 2023 14:58:16 +0100
Subject: [PATCH 1/2] Configurable LP Core clock

---
 esp-hal-common/src/soc/esp32c6/lp_core.rs | 36 +++++++++++++++++++++++
 esp32c6-lp-hal/src/delay.rs               |  2 +-
 esp32c6-lp-hal/src/lib.rs                 | 11 ++++++-
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/esp-hal-common/src/soc/esp32c6/lp_core.rs b/esp-hal-common/src/soc/esp32c6/lp_core.rs
index 4c322e03e7f..8ef3e4f0570 100644
--- a/esp-hal-common/src/soc/esp32c6/lp_core.rs
+++ b/esp-hal-common/src/soc/esp32c6/lp_core.rs
@@ -68,20 +68,56 @@ pub enum LpCoreWakeupSource {
     HpCpu,
 }
 
+/// Clock sources for the LP core
+#[derive(Debug, Clone, Copy)]
+pub enum LpCoreClockSource {
+    /// 17.5 MHz clock
+    ///
+    /// Might not be very accurate
+    RcFastClk,
+    /// 20 MHz clock
+    XtalD2Clk,
+}
+
 pub struct LpCore<'d> {
     _lp_core: PeripheralRef<'d, crate::soc::peripherals::LP_CORE>,
 }
 
 impl<'d> LpCore<'d> {
+    /// Create a new instance using [LpCoreClockSource::RcFastClk]
     pub fn new(lp_core: impl Peripheral<P = crate::soc::peripherals::LP_CORE> + 'd) -> Self {
+        LpCore::new_with_clock(lp_core, LpCoreClockSource::RcFastClk)
+    }
+
+    /// Create a new instance using the given clock
+    pub fn new_with_clock(
+        lp_core: impl Peripheral<P = crate::soc::peripherals::LP_CORE> + 'd,
+        clk_src: LpCoreClockSource,
+    ) -> Self {
         crate::into_ref!(lp_core);
+
+        match clk_src {
+            LpCoreClockSource::RcFastClk => unsafe {
+                (&*crate::soc::peripherals::LP_CLKRST::PTR)
+                    .lp_clk_conf
+                    .modify(|_, w| w.fast_clk_sel().clear_bit())
+            },
+            LpCoreClockSource::XtalD2Clk => unsafe {
+                (&*crate::soc::peripherals::LP_CLKRST::PTR)
+                    .lp_clk_conf
+                    .modify(|_, w| w.fast_clk_sel().set_bit())
+            },
+        }
+
         Self { _lp_core: lp_core }
     }
 
+    /// Stop the LP core
     pub fn stop(&mut self) {
         ulp_lp_core_stop();
     }
 
+    /// Start the LP core
     pub fn run(&mut self, wakeup_src: LpCoreWakeupSource) {
         ulp_lp_core_run(wakeup_src);
     }
diff --git a/esp32c6-lp-hal/src/delay.rs b/esp32c6-lp-hal/src/delay.rs
index e74a0c3c83b..2439495e521 100644
--- a/esp32c6-lp-hal/src/delay.rs
+++ b/esp32c6-lp-hal/src/delay.rs
@@ -14,7 +14,7 @@ pub struct Delay {
 impl Delay {
     pub fn new() -> Self {
         Self {
-            rv_delay: riscv::delay::McycleDelay::new(CPU_CLOCK),
+            rv_delay: riscv::delay::McycleDelay::new(unsafe { CPU_CLOCK }),
         }
     }
 }
diff --git a/esp32c6-lp-hal/src/lib.rs b/esp32c6-lp-hal/src/lib.rs
index 2c116927488..3bfa0fe3d12 100644
--- a/esp32c6-lp-hal/src/lib.rs
+++ b/esp32c6-lp-hal/src/lib.rs
@@ -14,7 +14,11 @@ pub mod riscv {
 }
 pub mod prelude;
 
-const CPU_CLOCK: u32 = 16_000_000;
+// LP_FAST_CLK is not very accurate, for now use a rough estimate
+const LP_FAST_CLK_HZ: u32 = 16_000_000;
+const XTAL_D2_CLK_HZ: u32 = 20_000_000;
+
+pub static mut CPU_CLOCK: u32 = LP_FAST_CLK_HZ;
 
 global_asm!(
     r#"
@@ -60,6 +64,11 @@ unsafe extern "C" fn lp_core_startup() -> ! {
         fn main() -> !;
     }
 
+    let clkrst = &*esp32c6_lp::LP_CLKRST::PTR;
+    if clkrst.lp_clk_conf.read().fast_clk_sel().bit_is_set() {
+        CPU_CLOCK = XTAL_D2_CLK_HZ;
+    }
+
     main();
 }
 

From 95a0f11ec99eeb82da5e40d7b3a03f1e07f1e145 Mon Sep 17 00:00:00 2001
From: bjoernQ <bjoern.quentin@mobile-j.de>
Date: Tue, 7 Nov 2023 15:00:58 +0100
Subject: [PATCH 2/2] CHANGELOG.md entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 70adf1ee5ac..6392c7f82d8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- ESP32-C6: LP core clock is configurable (#907)
 
 ### Changed