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// lpc176x serial port
//
// Copyright (C) 2018 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "LPC17xx.h" // LPC_UART0
#include "autoconf.h" // CONFIG_SERIAL_BAUD
#include "board/irq.h" // irq_save
#include "board/serial_irq.h" // serial_rx_data
#include "internal.h" // gpio_peripheral
#include "sched.h" // DECL_INIT
void
serial_init(void)
{
// Setup baud
LPC_UART0->LCR = (1<<7); // set DLAB bit
enable_pclock(PCLK_UART0);
uint32_t pclk = SystemCoreClock;
uint32_t div = pclk / (CONFIG_SERIAL_BAUD * 16);
LPC_UART0->DLL = div & 0xff;
LPC_UART0->DLM = (div >> 8) & 0xff;
LPC_UART0->LCR = 3; // 8N1 ; clear DLAB bit
// Enable fifo
LPC_UART0->FCR = 0x01;
// Setup pins
gpio_peripheral(GPIO(0, 2), 1, 0);
gpio_peripheral(GPIO(0, 3), 1, 0);
// Enable receive irq
NVIC_SetPriority(UART0_IRQn, 0);
NVIC_EnableIRQ(UART0_IRQn);
LPC_UART0->IER = 0x01;
}
DECL_INIT(serial_init);
// Write tx bytes to the serial port
static void
kick_tx(void)
{
for (;;) {
if (!(LPC_UART0->LSR & (1<<5))) {
// Output fifo full - enable tx irq
LPC_UART0->IER = 0x03;
break;
}
uint8_t data;
int ret = serial_get_tx_byte(&data);
if (ret) {
// No more data to send - disable tx irq
LPC_UART0->IER = 0x01;
break;
}
LPC_UART0->THR = data;
}
}
void __visible
UART0_IRQHandler(void)
{
uint32_t iir = LPC_UART0->IIR, status = iir & 0x0f;
if (status == 0x04)
serial_rx_byte(LPC_UART0->RBR);
else if (status == 0x02)
kick_tx();
}
void
serial_enable_tx_irq(void)
{
if (LPC_UART0->LSR & (1<<5)) {
irqstatus_t flag = irq_save();
kick_tx();
irq_restore(flag);
}
}
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