1 files changed, 60 insertions, 0 deletions
diff --git a/src/kernel/serial.c b/src/kernel/serial.c
new file mode 100644
index 0000000..6f112a8
--- /dev/null
+++ b/src/kernel/serial.c
@@ -0,0 +1,60 @@
+/**
+ * @file serial.c
+ * Provides basic serial IO (through STM debug stuff)
+ *
+ * Copyright (C) 2018 Clyne Sullivan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <arch/stm/stm32l476xx.h>
+#include "gpio.h"
+#include "clock.h"
+
+void serial_init(uint32_t baud)
+{
+	gpio_mode(GPIOA, 2, ALTERNATE);
+	gpio_mode(GPIOA, 3, ALTERNATE);
+	GPIOA->AFR[0] &= ~(0x0000FF00);
+	GPIOA->AFR[0] |= 0x00007700;
+	RCC->APB1ENR1 |= RCC_APB1ENR1_USART2EN;
+
+	// start usart device
+	USART2->BRR = 80000000L / baud;
+	USART2->CR1 |= USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;
+}
+
+void serial_put(int c)
+{
+	while (!(USART2->ISR & USART_ISR_TXE));
+	USART2->TDR = c & 0xFF;
+}
+
+char serial_get(void)
+{
+	while (!(USART2->ISR & USART_ISR_RXNE))
+		delay(10);
+	return USART2->RDR & 0xFF;
+}
+
+void serial_gets(char *buf, int max)
+{
+	uint16_t index = 0;
+
+	do {
+		buf[index] = serial_get();
+		serial_put(buf[index]);
+	} while (buf[index] != '\r' && index++ < max);
+	buf[index] = '\0';
+}