stm32f107_basic: Add support for a simple stm32f107 platform

This platform is a basic waveshare stm32f107 devkit which contains a
USART, USB device port, some buttons and some LEDs.  Unfortunately not
enough to bring up networking, but enough to test building and a
simple contiki shell

platform/stm32f107_basic/dev/debug-uart.c

@@ -0,0 +1,95 @@
+#include <libopencm3/stm32/usart.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/stm32/f1/gpio.h>
+
+#include <gqueue.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <errno.h>
+
+DECLARE_QUEUE(char, uart_tx_buf, 256);
+DECLARE_QUEUE(char, uart_rx_buf, 256);
+
+static void uart_init_gpio(void)
+{
+	gpio_set_mode(GPIOA,
+	              GPIO_MODE_OUTPUT_50_MHZ,
+	              GPIO_CNF_OUTPUT_ALTFN_PUSHPULL,
+	              GPIO9);
+
+	gpio_set_mode(GPIOA,
+	              GPIO_MODE_INPUT,
+	              GPIO_CNF_INPUT_FLOAT,
+	              GPIO10);
+
+	/* USART lines should idle high */
+	gpio_set(GPIOA, GPIO9);
+	gpio_set(GPIOA, GPIO10);
+}
+
+void uart_init(int baud)
+{
+	uart_init_gpio();
+
+	nvic_enable_irq(NVIC_USART1_IRQ);
+	nvic_set_priority(NVIC_USART1_IRQ, 2);
+
+	usart_set_baudrate(USART1, baud);
+	usart_set_databits(USART1, 8);
+	usart_set_parity(USART1, USART_PARITY_NONE);
+	usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
+	usart_set_stopbits(USART1, USART_CR2_STOPBITS_1);
+	usart_set_mode(USART1, USART_MODE_TX_RX);
+	usart_enable_rx_interrupt(USART1);
+	usart_enable(USART1);
+
+	/* This ensures stdio doesn't use its own buffers */
+	setvbuf(stdin, NULL, _IONBF, 0);
+	setvbuf(stdout, NULL, _IONBF, 0);
+}
+
+int uart_putchar(char c)
+{
+	if( c == '\n')
+		uart_putchar('\r');
+	if(!queue_is_full(&uart_tx_buf)) {
+		queue_enqueue(&uart_tx_buf, &c);
+	} else {
+		return -ENOMEM;
+	}
+
+	usart_enable_tx_interrupt(USART1);
+
+	return 0;
+}
+
+int uart_getchar(char *c)
+{
+	if(!queue_is_empty(&uart_rx_buf)) {
+		queue_dequeue(&uart_rx_buf, c);
+		return 0;
+	} else {
+		return -ENODATA;
+	}
+}
+
+void usart1_isr(void)
+{
+	char c;
+	if (usart_get_flag(USART1, USART_SR_TXE)) {
+		if (!queue_is_empty(&uart_tx_buf)) {
+			queue_dequeue(&uart_tx_buf, &c);
+			usart_send(USART1, (uint16_t)c);
+		} else {
+			usart_disable_tx_interrupt(USART1);
+		}
+	}
+
+
+	if (usart_get_flag(USART1, USART_SR_RXNE)) {
+		if (!queue_is_full(&uart_rx_buf)) {
+			c = usart_recv(USART1);
+			queue_enqueue(&uart_rx_buf, &c);
+		}
+	}
+}

platform/stm32f107_basic/dev/debug-uart.h

@@ -0,0 +1,14 @@
+/**
+ * USART driver for STM32F1xx w/ libopencm3 peripherl lib
+ * (c) 2012 Blessed Contraptions
+ * Jeff Ciesielski <jeff.ciesielski@gmail.com>
+ */
+
+#ifndef _UART_H_
+#define _UART_H_
+
+int uart_putchar(char c);
+int uart_getchar(char *c);
+void uart_init(int baud);
+
+#endif