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/*
* (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>
#include <libopencm3/cm3/nvic.h>
#include "serial.h"
#define USART_CONSOLE USART1
int _write(int fd, char *ptr, int len) __attribute__((used));
struct ring {
uint8_t *data;
int size;
volatile int begin;
volatile int end;
};
#define BUFFER_SIZE 256
struct ring rx_ring;
struct ring tx_ring;
uint8_t rx_ring_buffer[BUFFER_SIZE];
uint8_t tx_ring_buffer[BUFFER_SIZE];
static void ring_init(struct ring *ring, uint8_t *buf, int size)
{
ring->data = buf;
ring->size = size;
ring->begin = 0;
ring->end = 0;
}
static int ring_write_ch(struct ring *ring, uint8_t ch)
{
int ep = (ring->end + 1) % ring->size;
if ((ep) != ring->begin) {
ring->data[ring->end] = ch;
ring->end = ep;
return 1;
}
return -1;
}
static int ring_write(struct ring *ring, uint8_t *data, int size)
{
int i;
for (i = 0; i < size; i++) {
if (ring_write_ch(ring, data[i]) < 0)
return -i;
}
return i;
}
static int ring_read_ch(struct ring *ring)
{
int ret = -1;
if (ring->begin != ring->end) {
ret = ring->data[ring->begin];
ring->begin = (ring->begin +1) % ring->size;
}
return ret;
}
void usart_setup(void)
{
/* Initialize output ring buffer. */
ring_init(&rx_ring, rx_ring_buffer, BUFFER_SIZE);
ring_init(&tx_ring, tx_ring_buffer, BUFFER_SIZE);
/* Enable the USART1 interrupt. */
nvic_enable_irq(NVIC_USART1_IRQ);
/* Setup GPIO pin GPIO_USART1_TX/LED_GREEN_PIN on GPIO port A for transmit. */
/* TODO: USART1 --> USART_CONSOLE */
gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
/* Setup GPIO pin GPIO_USART1_RE_RX on GPIO port B for receive. */
gpio_set_mode(GPIOA, GPIO_MODE_INPUT,
GPIO_CNF_INPUT_FLOAT, GPIO_USART1_RX);
/* Setup UART parameters. */
// usart_set_baudrate(USART_CONSOLE, 38400);
usart_set_baudrate(USART_CONSOLE, 115200);
usart_set_databits(USART_CONSOLE, 8);
usart_set_stopbits(USART_CONSOLE, USART_STOPBITS_1);
usart_set_parity(USART_CONSOLE, USART_PARITY_NONE);
usart_set_flow_control(USART_CONSOLE, USART_FLOWCONTROL_NONE);
usart_set_mode(USART_CONSOLE, USART_MODE_TX_RX);
/* Enable USART1 Receive interrupt. */
USART_CR1(USART1) |= USART_CR1_RXNEIE;
/* Finally enable the USART. */
usart_enable(USART_CONSOLE);
}
void usart1_isr(void)
{
/* Check if we were called because of RXNE. */
if (((USART_CR1(USART1) & USART_CR1_RXNEIE) != 0) &&
((USART_SR(USART1) & USART_SR_RXNE) != 0)) {
/* Retrieve the data from the peripheral. */
ring_write_ch(&rx_ring, usart_recv(USART1));
}
/* Check if we were called because of TXE. */
if (((USART_CR1(USART1) & USART_CR1_TXEIE) != 0) &&
((USART_SR(USART1) & USART_SR_TXE) != 0)) {
int data;
data = ring_read_ch(&tx_ring);
if (data == -1) {
/* Disable the TXE interrupt, it's no longer needed. */
USART_CR1(USART1) &= ~USART_CR1_TXEIE;
} else {
/* Put data into the transmit register. */
usart_send(USART1, data);
}
}
}
/*--------------------------------------------------------------------------*/
void serial_setup(void)
{
usart_setup();
}
/*--------------------------------------------------------------------------*/
/**
* Use USART_CONSOLE as a console.
* This is a syscall for newlib
* @param fd
* @param ptr
* @param len
* @return
*/
int _write(int fd, char *ptr, int len)
{
int i;
if (fd == STDOUT_FILENO || fd == STDERR_FILENO) {
for (i = 0; i < len; i++) {
if (ptr[i] == '\n') {
serial_putc('\r');
}
serial_putc(ptr[i]);
}
return i;
}
errno = EIO;
return -1;
}
int serial_getc(void)
{
return ring_read_ch(&rx_ring);
}
void serial_putc(uint8_t data)
{
while (ring_write_ch(&tx_ring, data) < 0)
;
/* Enable the TXE interrupt. */
USART_CR1(USART1) |= USART_CR1_TXEIE;
}
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