From ac19c4ef1f65ec598ec1eef2a87b112063777e83 Mon Sep 17 00:00:00 2001
From: Andrey Sverdlichenko <blaze@rusty.zone>
Date: Sun, 19 Jan 2025 19:29:21 -0500
Subject: [PATCH] Cleanup device initialization

---
 src/adc.rs          | 20 +++++++++++++-------
 src/i2c.rs          |  4 ++--
 src/lib.rs          |  5 -----
 src/timer.rs        |  6 ++++--
 src/timer/lptim.rs  | 14 +++++++++++---
 src/timer/timers.rs | 14 +++++++++++---
 6 files changed, 41 insertions(+), 22 deletions(-)

diff --git a/src/adc.rs b/src/adc.rs
index 7a11755..a10e162 100644
--- a/src/adc.rs
+++ b/src/adc.rs
@@ -4,18 +4,22 @@ use crate::pac::adc::chselr1;
 use crate::pac::ADC;
 use crate::rcc::{Rcc, ResetEnable};
 
+pub trait AdcExt {
+    fn constrain(self, rcc: &Rcc) -> Adc;
+}
+
 pub struct Adc {
     adc: ADC,
     vref_cache: Option<u16>,
 }
 
-impl Adc {
-    pub fn new(adc: ADC, rcc: &Rcc) -> Self {
+impl AdcExt for ADC {
+    fn constrain(self, rcc: &Rcc) -> Adc {
         ADC::enable(rcc);
         ADC::reset(rcc);
 
         // Enable ADC voltage regulator.
-        adc.cr().modify(|_, w| w.advregen().enabled());
+        self.cr().modify(|_, w| w.advregen().enabled());
 
         // RM0444 15.3.3 Calibration can only be initiated when the ADC voltage regulator is
         // enabled (ADVREGEN = 1 and tADCVREG_SETUP has elapsed) and the ADC is disabled
@@ -24,18 +28,20 @@ impl Adc {
         // Round up for a safety margin.
         cortex_m::asm::delay(2000);
 
-        adc.cfgr1().modify(|_, w| w.chselrmod().sequence());
+        self.cfgr1().modify(|_, w| w.chselrmod().sequence());
 
         // Set clock to PCLK/2.
         // TODO: make this configurable.
-        adc.cfgr2().modify(|_, w| w.ckmode().pclk_div2());
+        self.cfgr2().modify(|_, w| w.ckmode().pclk_div2());
 
-        Self {
-            adc,
+        Adc {
+            adc: self,
             vref_cache: None,
         }
     }
+}
 
+impl Adc {
     pub fn calibrate(&mut self) {
         self.adc.isr().write(|w| w.eocal().clear());
         self.adc.cr().modify(|_, w| w.adcal().start_calibration());
diff --git a/src/i2c.rs b/src/i2c.rs
index c2cd7c7..ca150c7 100644
--- a/src/i2c.rs
+++ b/src/i2c.rs
@@ -68,7 +68,7 @@ impl Config {
 
 /// Extension trait to create I2C bus from a raw device
 pub trait I2cExt<I2C> {
-    fn i2c<SDA, SCL>(self, sda: SDA, scl: SCL, config: &Config, rcc: &Rcc) -> I2c<I2C>
+    fn constrain<SDA, SCL>(self, sda: SDA, scl: SCL, config: &Config, rcc: &Rcc) -> I2c<I2C>
     where
         SDA: SdaPin<I2C>,
         SCL: SclPin<I2C>;
@@ -132,7 +132,7 @@ macro_rules! i2c {
         )+
 
         impl I2cExt<$I2C> for $I2C {
-            fn i2c<SDA, SCL>(self, sda: SDA, scl: SCL, config: &Config, rcc: &Rcc) -> I2c<$I2C>
+            fn constrain<SDA, SCL>(self, sda: SDA, scl: SCL, config: &Config, rcc: &Rcc) -> I2c<$I2C>
             where
                 SDA: SdaPin<$I2C>,
                 SCL: SclPin<$I2C>,
diff --git a/src/lib.rs b/src/lib.rs
index c16f03f..fff5f36 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,11 +1,6 @@
 #![no_std]
 #![deny(unsafe_code)]
 
-// TODO: cleanup HAL modules
-// 1. use constrain() for creating peripherals via extension traits
-// 2. except for GPIO, which is canonically split()
-// 3. and except for timers, which can be turned into counter, pwm, etc
-
 pub mod adc;
 pub mod exti;
 pub mod gpio;
diff --git a/src/timer.rs b/src/timer.rs
index 5bc1a93..b7b2552 100644
--- a/src/timer.rs
+++ b/src/timer.rs
@@ -2,5 +2,7 @@
 mod lptim;
 mod timers;
 
-pub use lptim::{Disabled, Enabled, LowPowerTimer, LptimCounter, LptimEvent, LptimPrescaler};
-pub use timers::{Pwm, PwmPin, Timer};
+pub use lptim::{
+    Disabled, Enabled, LowPowerTimer, LptimCounter, LptimEvent, LptimExt, LptimPrescaler,
+};
+pub use timers::{Pwm, PwmPin, Timer, TimerExt};
diff --git a/src/timer/lptim.rs b/src/timer/lptim.rs
index 29a32ce..5efe37c 100644
--- a/src/timer/lptim.rs
+++ b/src/timer/lptim.rs
@@ -5,6 +5,12 @@ use crate::pac::{LPTIM1, LPTIM2};
 use crate::rcc::lptim::{LptimClock, LptimClockExt};
 use crate::rcc::{Rcc, ResetEnable};
 
+pub trait LptimExt {
+    fn constrain(self) -> LowPowerTimer<Self>
+    where
+        Self: Sized;
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum LptimPrescaler {
     Div1 = 0b000,
@@ -50,11 +56,13 @@ pub struct LptimCounter<TIM, STATE> {
 
 macro_rules! low_power_timer {
     ($TIM:ident) => {
-        impl LowPowerTimer<$TIM> {
-            pub fn new(timer: $TIM) -> Self {
-                Self { timer }
+        impl LptimExt for $TIM {
+            fn constrain(self) -> LowPowerTimer<Self> {
+                LowPowerTimer { timer: self }
             }
+        }
 
+        impl LowPowerTimer<$TIM> {
             pub fn upcounter(
                 self,
                 clock: LptimClock,
diff --git a/src/timer/timers.rs b/src/timer/timers.rs
index 4e84955..c2a1b6a 100644
--- a/src/timer/timers.rs
+++ b/src/timer/timers.rs
@@ -14,6 +14,12 @@ use crate::gpio::gpioe::{PE3, PE4, PE5, PE6};
 #[cfg(feature = "stm32g0b1")]
 use crate::pac::TIM4;
 
+pub trait TimerExt {
+    fn constrain(self) -> Timer<Self>
+    where
+        Self: Sized;
+}
+
 /// Wrapper for timer peripheral.
 #[derive(Debug)]
 pub struct Timer<TIM> {
@@ -34,11 +40,13 @@ pub struct Pwm<TIM> {
 
 macro_rules! general_purpose_timer {
     ($TIM:ident, $REG:tt) => {
-        impl Timer<$TIM> {
-            pub fn new(timer: $TIM) -> Self {
-                Self { timer }
+        impl TimerExt for $TIM {
+            fn constrain(self) -> Timer<Self> {
+                Timer { timer: self }
             }
+        }
 
+        impl Timer<$TIM> {
             pub fn upcounter(self, prescaler: u16, limit: $REG, rcc: &Rcc) -> Counter<$TIM> {
                 $TIM::enable(rcc);
                 $TIM::reset(rcc);