HAL_ChibiOS: automatically control pullup/pulldown on inverted UARTs

this makes setup of sport telemetry much easier

libraries/AP_HAL_ChibiOS/UARTDriver.cpp

@@ -1302,17 +1302,31 @@ bool UARTDriver::set_options(uint8_t options)
 
 #if defined(STM32F7) || defined(STM32H7) || defined(STM32F3)
     // F7 has built-in support for inversion in all uarts
+    ioline_t rx_line = (options & OPTION_SWAP)?sdef.tx_line:sdef.rx_line;
+    ioline_t tx_line = (options & OPTION_SWAP)?sdef.rx_line:sdef.tx_line;
     if (options & OPTION_RXINV) {
         cr2 |= USART_CR2_RXINV;
         _cr2_options |= USART_CR2_RXINV;
+        if (rx_line != 0) {
+            palLineSetPushPull(rx_line, PAL_PUSHPULL_PULLDOWN);
+        }
     } else {
         cr2 &= ~USART_CR2_RXINV;
+        if (rx_line != 0) {
+            palLineSetPushPull(rx_line, PAL_PUSHPULL_PULLUP);
+        }
     }
     if (options & OPTION_TXINV) {
         cr2 |= USART_CR2_TXINV;
         _cr2_options |= USART_CR2_TXINV;
+        if (tx_line != 0) {
+            palLineSetPushPull(tx_line, PAL_PUSHPULL_PULLDOWN);
+        }
     } else {
         cr2 &= ~USART_CR2_TXINV;
+        if (tx_line != 0) {
+            palLineSetPushPull(tx_line, PAL_PUSHPULL_PULLUP);
+        }
     }
     // F7 can also support swapping RX and TX pins
     if (options & OPTION_SWAP) {

libraries/AP_HAL_ChibiOS/UARTDriver.h

@@ -72,6 +72,8 @@ public:
         uint8_t dma_tx_stream_id;
         uint32_t dma_tx_channel_id;
 #endif
+        ioline_t tx_line;
+        ioline_t rx_line;
         ioline_t rts_line;
         int8_t rxinv_gpio;
         uint8_t rxinv_polarity;

libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c

@@ -342,7 +342,18 @@ iomode_t palReadLineMode(ioline_t line)
     }
     return ret;
 }
-#endif
+
+/*
+  set pin as pullup, pulldown or floating
+ */
+void palLineSetPushPull(ioline_t line, enum PalPushPull pp)
+{
+    ioportid_t port = PAL_PORT(line);
+    uint8_t pad = PAL_PAD(line);
+    port->PUPDR = (port->PUPDR & ~(3<<(pad*2))) | (pp<<(pad*2));
+}
+
+#endif // F7, H7, F4
 
 void stm32_cacheBufferInvalidate(const void *p, size_t size)
 {

libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h

@@ -80,6 +80,14 @@ void malloc_init(void);
  */
 #if defined(STM32F7) || defined(STM32H7) || defined(STM32F4)
 iomode_t palReadLineMode(ioline_t line);
+
+enum PalPushPull {
+    PAL_PUSHPULL_NOPULL=0,
+    PAL_PUSHPULL_PULLUP=1,
+    PAL_PUSHPULL_PULLDOWN=2
+};
+
+void palLineSetPushPull(ioline_t line, enum PalPushPull pp);
 #endif
 
 // set n RTC backup registers starting at given idx

libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py

@@ -985,6 +985,16 @@ def write_UART_config(f):
         else:
             error("Invalid element %s in UART_ORDER" % dev)
         devlist.append('HAL_%s_CONFIG' % dev)
+        if dev + "_TX" in bylabel:
+            p = bylabel[dev + '_TX']
+            tx_line = 'PAL_LINE(GPIO%s,%uU)' % (p.port, p.pin)
+        else:
+            tx_line = "0"
+        if dev + "_RX" in bylabel:
+            p = bylabel[dev + '_RX']
+            rx_line = 'PAL_LINE(GPIO%s,%uU)' % (p.port, p.pin)
+        else:
+            rx_line = "0"
         if dev + "_RTS" in bylabel:
             p = bylabel[dev + '_RTS']
             rts_line = 'PAL_LINE(GPIO%s,%uU)' % (p.port, p.pin)
@@ -1006,10 +1016,10 @@ def write_UART_config(f):
                 "#define HAL_%s_CONFIG { (BaseSequentialStream*) &SD%u, false, "
                 % (dev, n))
             if mcu_series.startswith("STM32F1"):
-                f.write("%s, " % rts_line)
+                f.write("%s, %s, %s, " % (tx_line, rx_line, rts_line))
             else:
-                f.write("STM32_%s_RX_DMA_CONFIG, STM32_%s_TX_DMA_CONFIG, %s, " %
+                f.write("STM32_%s_RX_DMA_CONFIG, STM32_%s_TX_DMA_CONFIG, %s, %s, %s, " %
-                        (dev, dev, rts_line))
+                        (dev, dev, tx_line, rx_line, rts_line))
 
             # add inversion pins, if any
             f.write("%d, " % get_gpio_bylabel(dev + "_RXINV"))