1 files changed, 78 insertions, 0 deletions
diff --git a/src/stm32/serial.c b/src/stm32/serial.c
new file mode 100644
index 00000000..0142aaa6
--- /dev/null
+++ b/src/stm32/serial.c
@@ -0,0 +1,78 @@
+// STM32 serial
+//
+// Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "autoconf.h" // CONFIG_SERIAL_BAUD
+#include "board/serial_irq.h" // serial_rx_byte
+#include "command.h" // DECL_CONSTANT_STR
+#include "internal.h" // enable_pclock
+#include "sched.h" // DECL_INIT
+
+// Select the configured serial port
+#if CONFIG_SERIAL_PORT == 1
+DECL_CONSTANT_STR("RESERVE_PINS_serial", "PA10,PA9");
+#define GPIO_Rx GPIO('A', 10)
+#define GPIO_Tx GPIO('A', 9)
+#define USARTx USART1
+#define USARTx_IRQn USART1_IRQn
+#define USARTx_IRQHandler USART1_IRQHandler
+#elif CONFIG_SERIAL_PORT == 2
+DECL_CONSTANT_STR("RESERVE_PINS_serial", "PA3,PA2");
+#define GPIO_Rx GPIO('A', 3)
+#define GPIO_Tx GPIO('A', 2)
+#define USARTx USART2
+#define USARTx_IRQn USART2_IRQn
+#define USARTx_IRQHandler USART2_IRQHandler
+#else
+DECL_CONSTANT_STR("RESERVE_PINS_serial", "PB11,PB10");
+#define GPIO_Rx GPIO('B', 11)
+#define GPIO_Tx GPIO('B', 10)
+#define USARTx USART3
+#define USARTx_IRQn USART3_IRQn
+#define USARTx_IRQHandler USART3_IRQHandler
+#endif
+
+#define CR1_FLAGS (USART_CR1_UE | USART_CR1_RE | USART_CR1_TE   \
+                   | USART_CR1_RXNEIE)
+
+void
+serial_init(void)
+{
+    enable_pclock((uint32_t)USARTx);
+
+    uint32_t pclk = get_pclock_frequency((uint32_t)USARTx);
+    uint32_t div = DIV_ROUND_CLOSEST(pclk, CONFIG_SERIAL_BAUD);
+    USARTx->BRR = (((div / 16) << USART_BRR_DIV_Mantissa_Pos)
+                   | ((div % 16) << USART_BRR_DIV_Fraction_Pos));
+    USARTx->CR1 = CR1_FLAGS;
+    NVIC_SetPriority(USARTx_IRQn, 0);
+    NVIC_EnableIRQ(USARTx_IRQn);
+
+    gpio_peripheral(GPIO_Rx, GPIO_FUNCTION(7), 1);
+    gpio_peripheral(GPIO_Tx, GPIO_FUNCTION(7), 0);
+}
+DECL_INIT(serial_init);
+
+void __visible
+USARTx_IRQHandler(void)
+{
+    uint32_t sr = USARTx->SR;
+    if (sr & (USART_SR_RXNE | USART_SR_ORE))
+        serial_rx_byte(USARTx->DR);
+    if (sr & USART_SR_TXE && USARTx->CR1 & USART_CR1_TXEIE) {
+        uint8_t data;
+        int ret = serial_get_tx_byte(&data);
+        if (ret)
+            USARTx->CR1 = CR1_FLAGS;
+        else
+            USARTx->DR = data;
+    }
+}
+
+void
+serial_enable_tx_irq(void)
+{
+    USARTx->CR1 = CR1_FLAGS | USART_CR1_TXEIE;
+}