teensy40: move txBuffer allocation to UART declaration

Author: ardnew

src/machine/board_teensy40.go

@@ -137,47 +137,54 @@ const (
 
 var (
 	UART1 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART6,
-		rxMux:  nxp.IOMUXC_LPUART6_RX_SELECT_INPUT_DAISY_GPIO_AD_B0_03_ALT2, // D0 (PA3 [AD_B0_03])
-		txMux:  nxp.IOMUXC_LPUART6_TX_SELECT_INPUT_DAISY_GPIO_AD_B0_02_ALT2, // D1 (PA2 [AD_B0_02])
+		Bus:      nxp.LPUART6,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART6_RX_SELECT_INPUT_DAISY_GPIO_AD_B0_03_ALT2, // D0 (PA3 [AD_B0_03])
+		txMux:    nxp.IOMUXC_LPUART6_TX_SELECT_INPUT_DAISY_GPIO_AD_B0_02_ALT2, // D1 (PA2 [AD_B0_02])
 	}
 	UART2 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART4,
-		rxMux:  nxp.IOMUXC_LPUART4_RX_SELECT_INPUT_DAISY_GPIO_B1_01_ALT2, // D7 (PB17 [B1_01])
-		txMux:  nxp.IOMUXC_LPUART4_TX_SELECT_INPUT_DAISY_GPIO_B1_00_ALT2, // D8 (PB16 [B1_00])
+		Bus:      nxp.LPUART4,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART4_RX_SELECT_INPUT_DAISY_GPIO_B1_01_ALT2, // D7 (PB17 [B1_01])
+		txMux:    nxp.IOMUXC_LPUART4_TX_SELECT_INPUT_DAISY_GPIO_B1_00_ALT2, // D8 (PB16 [B1_00])
 	}
 	UART3 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART2,
-		rxMux:  nxp.IOMUXC_LPUART2_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_03_ALT2, // D15 (PA19 [AD_B1_03])
-		txMux:  nxp.IOMUXC_LPUART2_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_02_ALT2, // D14 (PA18 [AD_B1_02])
+		Bus:      nxp.LPUART2,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART2_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_03_ALT2, // D15 (PA19 [AD_B1_03])
+		txMux:    nxp.IOMUXC_LPUART2_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_02_ALT2, // D14 (PA18 [AD_B1_02])
 	}
 	UART4 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART3,
-		rxMux:  nxp.IOMUXC_LPUART3_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_07_ALT2, // D16 (PA23 [AD_B1_07])
-		txMux:  nxp.IOMUXC_LPUART3_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_06_ALT2, // D17 (PA22 [AD_B1_06])
+		Bus:      nxp.LPUART3,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART3_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_07_ALT2, // D16 (PA23 [AD_B1_07])
+		txMux:    nxp.IOMUXC_LPUART3_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_06_ALT2, // D17 (PA22 [AD_B1_06])
 	}
 	UART5 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART8,
-		rxMux:  nxp.IOMUXC_LPUART8_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_11_ALT2, // D21 (PA27 [AD_B1_11])
-		txMux:  nxp.IOMUXC_LPUART8_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_10_ALT2, // D20 (PA26 [AD_B1_10])
+		Bus:      nxp.LPUART8,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART8_RX_SELECT_INPUT_DAISY_GPIO_AD_B1_11_ALT2, // D21 (PA27 [AD_B1_11])
+		txMux:    nxp.IOMUXC_LPUART8_TX_SELECT_INPUT_DAISY_GPIO_AD_B1_10_ALT2, // D20 (PA26 [AD_B1_10])
 	}
 	UART6 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART1,
+		Bus:      nxp.LPUART1,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
 		// LPUART1 not connected via IOMUXC
 		//   RX: D24 (PA12 [AD_B0_12])
 		//   TX: D25 (PA13 [AD_B0_13])
 	}
 	UART7 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    nxp.LPUART7,
-		rxMux:  nxp.IOMUXC_LPUART7_RX_SELECT_INPUT_DAISY_GPIO_EMC_32_ALT2, // D28 (PC18 [EMC_32])
-		txMux:  nxp.IOMUXC_LPUART7_TX_SELECT_INPUT_DAISY_GPIO_EMC_31_ALT2, // D29 (PD31 [EMC_31])
+		Bus:      nxp.LPUART7,
+		Buffer:   NewRingBuffer(),
+		txBuffer: NewRingBuffer(),
+		rxMux:    nxp.IOMUXC_LPUART7_RX_SELECT_INPUT_DAISY_GPIO_EMC_32_ALT2, // D28 (PC18 [EMC_32])
+		txMux:    nxp.IOMUXC_LPUART7_TX_SELECT_INPUT_DAISY_GPIO_EMC_31_ALT2, // D29 (PD31 [EMC_31])
 	}
 )
 

src/machine/machine_mimxrt1062_uart.go

@@ -15,6 +15,10 @@ type UART struct {
 	Buffer    *RingBuffer
 	Interrupt interrupt.Interrupt
 
+	// txBuffer should be allocated globally (such as when UART is created) to
+	// prevent it being reclaimed or cleaned up prematurely.
+	txBuffer *RingBuffer
+
 	// These hold the input selector ("daisy chain") values of the IOMUXC
 	// controller that selects which pins are connected to the LPUART device;
 	// define these where the UART instance is declared.
@@ -30,7 +34,6 @@ type UART struct {
 	configured   bool
 	msbFirst     bool
 	transmitting volatile.Register32
-	txBuffer     *RingBuffer
 }
 
 func (uart *UART) isTransmitting() bool { return uart.transmitting.Get() != 0 }
@@ -195,9 +198,6 @@ func (uart *UART) Sync() error {
 
 // WriteByte writes a single byte of data to the UART interface.
 func (uart *UART) WriteByte(c byte) error {
-	if nil == uart.txBuffer {
-		uart.txBuffer = NewRingBuffer()
-	}
 	uart.startTransmitting()
 	for !uart.txBuffer.Put(c) {
 	}