Everything you need to bootload with an SCB UART in PSoC 4

main.c

void CyBtldrCommStart(void) {
	UART_Start();
}

void CyBtldrCommStop (void) {
	UART_Stop();
}

void CyBtldrCommReset(void) {
	UART_SpiUartClearRxBuffer();
	UART_SpiUartClearTxBuffer();
}

cystatus CyBtldrCommWrite(uint8* buffer, uint16 size, uint16* count, uint8 timeOut) {
	for(*count = 0; *count < size; (*count)++) {
		UART_UartPutChar(buffer[*count]);
	}
	
	return CYRET_SUCCESS;
}

cystatus CyBtldrCommRead (uint8* buffer, uint16 size, uint16* count, uint8 timeOut) {
	int timeoutUs = timeOut * 10000;
	cystatus status = CYRET_TIMEOUT;
	
	*count = 0;
	while(*count < size && timeoutUs >= 0) {
		if(UART_SpiUartGetRxBufferSize() > 0) {
			buffer[(*count)++] = UART_UartGetByte();
			// Switch to byte-to-byte timeout and mark as success
			timeoutUs = 10000; //10mS
			status = CYRET_SUCCESS;
		} else {
			CyDelayUs(10);
			timeoutUs -= 10;
		}
	}
	
	return status;
}