From ce8ad3650ac483cead4784f97ab8ffd7faa8994d Mon Sep 17 00:00:00 2001
From: Kenneth Bell <ken@netleap.io>
Date: Sat, 13 Mar 2021 09:16:43 -0800
Subject: stm32l0: use unified UART logic

---
 src/machine/machine_stm32_uart.go   |  2 +-
 src/machine/machine_stm32l0.go      | 17 +++++-----
 src/machine/machine_stm32l0_uart.go | 64 -------------------------------------
 3 files changed, 9 insertions(+), 74 deletions(-)
 delete mode 100644 src/machine/machine_stm32l0_uart.go

diff --git a/src/machine/machine_stm32_uart.go b/src/machine/machine_stm32_uart.go
index 5f065f4f6..64b3345a2 100644
--- a/src/machine/machine_stm32_uart.go
+++ b/src/machine/machine_stm32_uart.go
@@ -1,4 +1,4 @@
-// +build stm32,!stm32l0
+// +build stm32
 
 package machine
 
diff --git a/src/machine/machine_stm32l0.go b/src/machine/machine_stm32l0.go
index 81cb2c115..f5a8fb4b6 100644
--- a/src/machine/machine_stm32l0.go
+++ b/src/machine/machine_stm32l0.go
@@ -6,7 +6,6 @@ package machine
 
 import (
 	"device/stm32"
-	"runtime/interrupt"
 	"unsafe"
 )
 
@@ -189,14 +188,6 @@ func enableAltFuncClock(bus unsafe.Pointer) {
 
 //---------- UART related types and code
 
-// UART representation
-type UART struct {
-	Buffer          *RingBuffer
-	Bus             *stm32.USART_Type
-	Interrupt       interrupt.Interrupt
-	AltFuncSelector uint8
-}
-
 // Configure the UART.
 func (uart UART) configurePins(config UARTConfig) {
 	// enable the alternate functions on the TX and RX pins
@@ -222,6 +213,14 @@ func (uart UART) getBaudRateDivisor(baudRate uint32) uint32 {
 	return rate
 }
 
+// Register names vary by ST processor, these are for STM L0 family
+func (uart *UART) setRegisters() {
+	uart.rxReg = &uart.Bus.RDR
+	uart.txReg = &uart.Bus.TDR
+	uart.statusReg = &uart.Bus.ISR
+	uart.txEmptyFlag = stm32.USART_ISR_TXE
+}
+
 //---------- SPI related types and code
 
 // SPI on the STM32Fxxx using MODER / alternate function pins
diff --git a/src/machine/machine_stm32l0_uart.go b/src/machine/machine_stm32l0_uart.go
deleted file mode 100644
index 80285937b..000000000
--- a/src/machine/machine_stm32l0_uart.go
+++ /dev/null
@@ -1,64 +0,0 @@
-// +build stm32,stm32l0
-
-package machine
-
-// Peripheral abstraction layer for UARTs on the stm32 family.
-
-import (
-	"device/stm32"
-	"runtime/interrupt"
-	"unsafe"
-)
-
-// Configure the UART.
-func (uart UART) Configure(config UARTConfig) {
-	// Default baud rate to 115200.
-	if config.BaudRate == 0 {
-		config.BaudRate = 115200
-	}
-
-	// Set the GPIO pins to defaults if they're not set
-	if config.TX == 0 && config.RX == 0 {
-		config.TX = UART_TX_PIN
-		config.RX = UART_RX_PIN
-	}
-
-	// Enable USART clock
-	enableAltFuncClock(unsafe.Pointer(uart.Bus))
-
-	uart.configurePins(config)
-
-	// Set baud rate
-	uart.SetBaudRate(config.BaudRate)
-
-	// Enable USART port, tx, rx and rx interrupts
-	uart.Bus.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)
-
-	// Enable RX IRQ
-	uart.Interrupt.SetPriority(0xc0)
-	uart.Interrupt.Enable()
-}
-
-// handleInterrupt should be called from the appropriate interrupt handler for
-// this UART instance.
-func (uart *UART) handleInterrupt(interrupt.Interrupt) {
-	uart.Receive(byte((uart.Bus.RDR.Get() & 0xFF)))
-}
-
-// SetBaudRate sets the communication speed for the UART. Defer to chip-specific
-// routines for calculation
-func (uart UART) SetBaudRate(br uint32) {
-	divider := uart.getBaudRateDivisor(br)
-	uart.Bus.BRR.Set(divider)
-}
-
-// WriteByte writes a byte of data to the UART.
-func (uart UART) WriteByte(c byte) error {
-
-	uart.Bus.TDR.Set(uint32(c))
-
-	for !uart.Bus.ISR.HasBits(stm32.USART_ISR_TXE) {
-	}
-
-	return nil
-}
-- 
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