From 2e31f5e437645bb6c21ace8c4fe9c435ff88bdec Mon Sep 17 00:00:00 2001
From: Vegard Storheil Eriksen <zyp@jvnv.net>
Date: Sun, 17 Apr 2022 00:46:31 +0200
Subject: stm32_uart: Use constraints to make helper functions compatible with
 all versions.

---
 uart/stm32_uart.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/uart/stm32_uart.h b/uart/stm32_uart.h
index c4ba582..6db8305 100644
--- a/uart/stm32_uart.h
+++ b/uart/stm32_uart.h
@@ -2,6 +2,8 @@
 
 #include <mmio/mmio.h>
 
+#include <type_traits>
+
 struct STM32_UART_reg_v1_t {
 	volatile uint32_t SR;
 	volatile uint32_t DR;
@@ -42,10 +44,20 @@ struct STM32_UART_reg_lpv1_t {
 
 template <typename T>
 class STM32_UART_t : public mmio_ptr<T> {
+	static constexpr auto is_v1 = std::is_same_v<T, STM32_UART_reg_v1_t>;
+	static constexpr auto is_v2 = std::is_same_v<T, STM32_UART_reg_v2_t>;
+	static constexpr auto is_lpv1 = std::is_same_v<T, STM32_UART_reg_lpv1_t>;
+
     public:
         using mmio_ptr<T>::ptr;
 
-	void write_blocking(uint8_t data) const {
+	void write_blocking(uint8_t data) const requires is_v1 {
+		// wait for TXE/TXFNF
+		while (!(ptr()->SR & (1<<7)));
+		ptr()->DR = data;
+	}
+
+	void write_blocking(uint8_t data) const requires is_v2 || is_lpv1 {
 		// wait for TXE/TXFNF
 		while (!(ptr()->ISR & (1<<7)));
 		ptr()->TDR = data;
-- 
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