chores: improve serial / timer conflict detection

radio/src/targets/common/arm/stm32/stm32_serial_driver.cpp

@@ -226,16 +226,15 @@ static void _on_rx_fifo(uint8_t data)
 
 static void* stm32_serial_init(void* hw_def, const etx_serial_init* params)
 {
-  // TODO: check if port is already in use
   auto sp = (const stm32_serial_port*)hw_def;
   if (!sp) return nullptr;
 
   auto usart = sp->usart;
   auto st = stm32_serial_find_state(usart);
   if (!st || st->sp) return nullptr;
 
-  stm32_usart_init(usart, params);
-  st->sp = sp; // TODO: only iff init() is sucessful
+  if (!stm32_usart_init(usart, params)) return nullptr;
+  st->sp = sp;
 
   if (params->direction & ETX_Dir_TX) {
     // prepare for send_byte()

radio/src/targets/common/arm/stm32/stm32_softserial_driver.cpp

@@ -21,6 +21,7 @@
 
 #include "stm32_softserial_driver.h"
 #include "stm32_exti_driver.h"
+#include "stm32_timer.h"
 
 #include <string.h>
 
@@ -67,9 +68,13 @@ static inline void _rx_fifo_clear()
   rxRidx = 0;
 }
 
-static void _softserial_init_rx(const stm32_softserial_rx_port* port,
+static bool _softserial_init_rx(const stm32_softserial_rx_port* port,
                                 const etx_serial_init* params)
 {
+  // Test if pin is in reset state
+  uint32_t mode = LL_GPIO_GetPinMode(port->GPIOx, port->GPIO_Pin);
+  if (mode != LL_GPIO_MODE_INPUT) return false;
+
   rxBitCount = 0;
   rxBuffer = port->buffer.buffer;
   rxBufLen = port->buffer.length;
@@ -80,11 +85,11 @@ static void _softserial_init_rx(const stm32_softserial_rx_port* port,
   LL_TIM_StructInit(&timInit);
 
   uint32_t freq = params->baudrate * 16;
-  if (!freq) return;
+  if (!freq) return false;
 
   timInit.Prescaler = __LL_TIM_CALC_PSC(port->TIM_Freq, freq);
 
-  // TODO: enable_tim_clock(port->TIMx);
+  stm32_timer_enable_clock(port->TIMx);
   LL_TIM_Init(port->TIMx, &timInit);
 
   LL_TIM_ClearFlag_UPDATE(port->TIMx);
@@ -119,6 +124,8 @@ static void _softserial_init_rx(const stm32_softserial_rx_port* port,
   // Configure EXTI for raising edge (start bit; assuming inverted serial)
   _softserialPort = port;
   stm32_exti_enable(port->EXTI_Line, LL_EXTI_TRIGGER_RISING, _softserial_exti);
+
+  return true;
 }
 
 static void _softserial_deinit_gpio(const stm32_softserial_rx_port* port)
@@ -142,7 +149,7 @@ static void _softserial_deinit_rx(const stm32_softserial_rx_port* port)
 static void* stm32_softserial_rx_init(void* hw_def, const etx_serial_init* params)
 {
   auto port = (const stm32_softserial_rx_port*)hw_def;
-  _softserial_init_rx(port, params);
+  if (!_softserial_init_rx(port, params)) return nullptr;
   return hw_def;
 }
 

radio/src/targets/common/arm/stm32/stm32_usart_driver.cpp

@@ -221,8 +221,17 @@ void stm32_usart_deinit_rx_dma(const stm32_usart_t* usart)
 // - asymmetric bitrates for half-duplex (GHOST)
 // - ??? ability to switch RX DMA OFF ??? (-> X12S)
 //
-void stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params)
+bool stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params)
 {
+  // Test if the GPIO pins are in reset state
+  uint32_t pins = usart->GPIO_Pin;
+  while(pins != 0) {
+    uint32_t pin = 1 << POSITION_VAL(pins);
+    uint32_t mode = LL_GPIO_GetPinMode(usart->GPIOx, pin);
+    if (mode != LL_GPIO_MODE_INPUT) return false;
+    pins ^= pin;
+  }
+
   enable_usart_clock(usart->USARTx);
   LL_USART_DeInit(usart->USARTx);
 
@@ -258,8 +267,8 @@ void stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params)
     break;
 
   default:
-    // TODO: return some error
-    return;
+    stm32_usart_deinit(usart);
+    return false;
   }
 
   usartInit.HardwareFlowControl = LL_USART_HWCONTROL_NONE;
@@ -302,6 +311,8 @@ void stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params)
       LL_USART_IsEnabledIT_RXNE(usart->USARTx)) {
     _enable_usart_irq(usart);
   }
+
+  return true;
 }
 
 void stm32_usart_deinit(const stm32_usart_t* usart)

radio/src/targets/common/arm/stm32/stm32_usart_driver.h

@@ -54,7 +54,7 @@ struct stm32_usart_t {
     uint8_t                    txDMA_IRQ_Prio;
 };
 
-void stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params);
+bool stm32_usart_init(const stm32_usart_t* usart, const etx_serial_init* params);
 void stm32_usart_init_rx_dma(const stm32_usart_t* usart, const void* buffer, uint32_t length);
 void stm32_usart_enable_tx_irq(const stm32_usart_t* usart);
 void stm32_usart_set_idle_irq(const stm32_usart_t* usart, uint32_t enabled);