From 556ae0106bba66e49f62f45aa3cc458e31094dc7 Mon Sep 17 00:00:00 2001
From: Gerzain Mata <leftger@gmail.com>
Date: Fri, 8 Aug 2025 03:10:35 -0700
Subject: Working draft of VREFBUF driver

---
 embassy-stm32/Cargo.toml         |  4 +--
 embassy-stm32/src/lib.rs         |  2 ++
 embassy-stm32/src/vrefbuf/mod.rs | 69 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 embassy-stm32/src/vrefbuf/mod.rs

diff --git a/embassy-stm32/Cargo.toml b/embassy-stm32/Cargo.toml
index 145a89b77..590216c21 100644
--- a/embassy-stm32/Cargo.toml
+++ b/embassy-stm32/Cargo.toml
@@ -81,7 +81,7 @@ futures-util = { version = "0.3.30", default-features = false }
 sdio-host = "0.9.0"
 critical-section = "1.1"
 #stm32-metapac = { version = "16" }
-stm32-metapac = { git = "https://github.com/embassy-rs/stm32-data-generated", tag = "stm32-data-cad609e02a866422ffdbb8e07be26311cfdd07d9" }
+stm32-metapac = { git = "https://github.com/embassy-rs/stm32-data-generated", tag = "stm32-data-f0ef9106642ed869e7cfbf82d891d364c98ebb43" }
 
 vcell = "0.1.3"
 nb = "1.0.0"
@@ -110,7 +110,7 @@ proc-macro2 = "1.0.36"
 quote = "1.0.15"
 
 #stm32-metapac = { version = "16", default-features = false, features = ["metadata"]}
-stm32-metapac = { git = "https://github.com/embassy-rs/stm32-data-generated", tag = "stm32-data-cad609e02a866422ffdbb8e07be26311cfdd07d9", default-features = false, features = ["metadata"] }
+stm32-metapac = { git = "https://github.com/embassy-rs/stm32-data-generated", tag = "stm32-data-f0ef9106642ed869e7cfbf82d891d364c98ebb43", default-features = false, features = ["metadata"] }
 
 [features]
 default = ["rt"]
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index a676677e1..e4a8ff0ab 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -125,6 +125,8 @@ pub mod uid;
 pub mod usart;
 #[cfg(any(usb, otg))]
 pub mod usb;
+#[cfg(vrefbuf)]
+pub mod vrefbuf;
 #[cfg(iwdg)]
 pub mod wdg;
 #[cfg(xspi)]
diff --git a/embassy-stm32/src/vrefbuf/mod.rs b/embassy-stm32/src/vrefbuf/mod.rs
new file mode 100644
index 000000000..2546ccfed
--- /dev/null
+++ b/embassy-stm32/src/vrefbuf/mod.rs
@@ -0,0 +1,69 @@
+//! Voltage Reference Buffer (VREFBUF)
+// use core::ptr::{read_volatile, write_volatile};
+use core::marker::PhantomData;
+
+use embassy_hal_internal::PeripheralType;
+use stm32_metapac::vrefbuf::vals::*;
+
+use crate::pac::RCC;
+use crate::Peri;
+
+/// Voltage Reference (VREFBUF) driver.
+pub struct VoltageReferenceBuffer<'d, T: Instance> {
+    vrefbuf: PhantomData<&'d mut T>,
+}
+
+impl<'d, T: Instance> VoltageReferenceBuffer<'d, T> {
+    /// Creates an VREFBUF (Voltage Reference) instance with a voltage scale and impedance mode.
+    ///
+    /// [Self] has to be started with [Self::new()].
+    pub fn new(_instance: Peri<'d, T>, voltage_scale: Vrs, impedance_mode: Hiz) -> Self {
+        #[cfg(rcc_wba)]
+        {
+            RCC.apb7enr().modify(|w| w.set_vrefen(true));
+        }
+        #[cfg(any(rcc_u5, rcc_h50, rcc_h5))]
+        {
+            RCC.apb3enr().modify(|w| w.set_vrefen(true));
+        }
+        #[cfg(any(rcc_h7rs, rcc_h7rm0433, rcc_h7ab, rcc_h7))]
+        {
+            RCC.apb4enr().modify(|w| w.set_vrefen(true));
+        }
+        let vrefbuf = T::regs();
+        vrefbuf.csr().modify(|w| {
+            w.set_hiz(impedance_mode);
+            w.set_envr(true);
+            w.set_vrs(voltage_scale);
+        });
+        while vrefbuf.csr().read().vrr() != false {
+            // wait...
+        }
+        trace!(
+            "Vrefbuf configured with voltage scale {} and impedance mode {}",
+            voltage_scale,
+            impedance_mode
+        );
+        VoltageReferenceBuffer { vrefbuf: PhantomData }
+    }
+}
+
+trait SealedInstance {
+    fn regs() -> crate::pac::vrefbuf::Vrefbuf;
+}
+
+/// VREFBUF instance trait.
+#[allow(private_bounds)]
+pub trait Instance: SealedInstance + PeripheralType {}
+
+foreach_peripheral!(
+    (vrefbuf, $inst:ident) => {
+        impl SealedInstance for crate::peripherals::$inst {
+            fn regs() -> crate::pac::vrefbuf::Vrefbuf {
+                crate::pac::$inst
+            }
+        }
+
+        impl Instance for crate::peripherals::$inst {}
+    };
+);
-- 
cgit