From 3e2b23d2f453d10324896484f9d045d2821bd567 Mon Sep 17 00:00:00 2001
From: Nils Ponsard <nils.ponsard@inria.fr>
Date: Fri, 18 Jul 2025 16:26:17 +0200
Subject: feat(embassy-nrf): add uicr hfxo workaround

In the MDK, there is a workaround "UICR_HFXO_WORKAROUND"  that resests
the HFXO values if they are erased. This is necessary on my nrf9151 to
have the modem working properly.

I found this thanks to these two messages:
https://github.com/diondokter/nrf-modem/issues/32#issuecomment-2704598018
https://devzone.nordicsemi.com/f/nordic-q-a/96093/nrf9160-porting-the-modem-library-to-work-with-bare-metal-application/435351?focus=true

Signed-off-by: Nils Ponsard <nils.ponsard@inria.fr>
---
 embassy-nrf/src/lib.rs | 43 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 44990ed85..8a88051b4 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -584,6 +584,8 @@ pub mod config {
 #[allow(unused)]
 mod consts {
     pub const UICR_APPROTECT: *mut u32 = 0x00FF8000 as *mut u32;
+    pub const UICR_HFXOSRC: *mut u32 = 0x00FF801C as *mut u32;
+    pub const UICR_HFXOCNT: *mut u32 = 0x00FF8020 as *mut u32;
     pub const UICR_SECUREAPPROTECT: *mut u32 = 0x00FF802C as *mut u32;
     pub const APPROTECT_ENABLED: u32 = 0x0000_0000;
     #[cfg(feature = "_nrf9120")]
@@ -650,13 +652,18 @@ unsafe fn uicr_write_masked(address: *mut u32, value: u32, mask: u32) -> WriteRe
         return WriteResult::Failed;
     }
 
-    let nvmc = pac::NVMC;
-    nvmc.config().write(|w| w.set_wen(pac::nvmc::vals::Wen::WEN));
-    while !nvmc.ready().read().ready() {}
-    address.write_volatile(value | !mask);
-    while !nvmc.ready().read().ready() {}
-    nvmc.config().write(|_| {});
-    while !nvmc.ready().read().ready() {}
+    // Nrf9151 errata 7, need to disable interrups + use DSB https://docs.nordicsemi.com/bundle/errata_nRF9151_Rev2/page/ERR/nRF9151/Rev2/latest/anomaly_151_7.html
+    cortex_m::interrupt::free(|_cs| {
+        let nvmc = pac::NVMC;
+
+        nvmc.config().write(|w| w.set_wen(pac::nvmc::vals::Wen::WEN));
+        while !nvmc.ready().read().ready() {}
+        address.write_volatile(value | !mask);
+        cortex_m::asm::dsb();
+        while !nvmc.ready().read().ready() {}
+        nvmc.config().write(|_| {});
+        while !nvmc.ready().read().ready() {}
+    });
 
     WriteResult::Written
 }
@@ -674,6 +681,28 @@ pub fn init(config: config::Config) -> Peripherals {
     #[allow(unused_mut)]
     let mut needs_reset = false;
 
+    // Workaround used in the nrf mdk: file system_nrf91.c , function SystemInit(), after `#if !defined(NRF_SKIP_UICR_HFXO_WORKAROUND)`
+    #[cfg(all(feature = "_nrf91", feature = "_s"))]
+    {
+        let uicr = pac::UICR_S;
+        let hfxocnt = uicr.hfxocnt().read().hfxocnt().to_bits();
+        let hfxosrc = uicr.hfxosrc().read().hfxosrc().to_bits();
+
+        if hfxosrc == 1 {
+            unsafe {
+                let _ = uicr_write(consts::UICR_HFXOSRC, 0);
+            }
+            needs_reset = true;
+        }
+
+        if hfxocnt == 255 {
+            unsafe {
+                let _ = uicr_write(consts::UICR_HFXOCNT, 32);
+            }
+            needs_reset = true;
+        }
+    }
+
     // Setup debug protection.
     #[cfg(not(feature = "_nrf51"))]
     match config.debug {
-- 
cgit