drivers/at86rf2xx: support frame retry reporting on AT86RFR2

drivers/at86rf2xx/at86rf2xx.c

@@ -145,6 +145,13 @@ void at86rf2xx_reset(at86rf2xx_t *dev)
     /* enable interrupts */
     at86rf2xx_reg_write(dev, AT86RF2XX_REG__IRQ_MASK,
                         AT86RF2XX_IRQ_STATUS_MASK__TRX_END);
+
+    /* enable TX start interrupt for retry counter */
+#ifdef AT86RF2XX_REG__IRQ_MASK1
+    at86rf2xx_reg_write(dev, AT86RF2XX_REG__IRQ_MASK1,
+                             AT86RF2XX_IRQ_STATUS_MASK1__TX_START);
+#endif
+
     /* clear interrupt flags */
     at86rf2xx_reg_read(dev, AT86RF2XX_REG__IRQ_STATUS);
 
@@ -189,10 +196,14 @@ size_t at86rf2xx_tx_load(at86rf2xx_t *dev, const uint8_t *data,
     return offset + len;
 }
 
-void at86rf2xx_tx_exec(const at86rf2xx_t *dev)
+void at86rf2xx_tx_exec(at86rf2xx_t *dev)
 {
     netdev_t *netdev = (netdev_t *)dev;
 
+#if AT86RF2XX_HAVE_RETRIES
+    dev->tx_retries = -1;
+#endif
+
     /* write frame length field in FIFO */
     at86rf2xx_sram_write(dev, 0, &(dev->tx_frame_len), 1);
     /* trigger sending of pre-loaded frame */

drivers/at86rf2xx/at86rf2xx_netdev.c

@@ -690,7 +690,7 @@ static void _isr_send_complete(at86rf2xx_t *dev, uint8_t trac_status)
         return;
     }
 /* Only radios with the XAH_CTRL_2 register support frame retry reporting */
-#if AT86RF2XX_HAVE_RETRIES
+#if AT86RF2XX_HAVE_RETRIES && defined(AT86RF2XX_REG__XAH_CTRL_2)
     dev->tx_retries = (at86rf2xx_reg_read(dev, AT86RF2XX_REG__XAH_CTRL_2)
                        & AT86RF2XX_XAH_CTRL_2__ARET_FRAME_RETRIES_MASK) >>
                       AT86RF2XX_XAH_CTRL_2__ARET_FRAME_RETRIES_OFFSET;
@@ -821,6 +821,26 @@ static void _isr(netdev_t *netdev)
 
 #if defined(MODULE_AT86RFA1) || defined(MODULE_AT86RFR2)
 
+/**
+ * @brief ISR for transceiver's TX_START interrupt
+ *
+ * In procedure TX_ARET the TRX24_TX_START interrupt is issued separately for every
+ * frame transmission and frame retransmission.
+ * Indicates the frame start of a transmitted acknowledge frame in procedure RX_AACK.
+ *
+ * Flow Diagram Manual p. 52 / 63
+ */
+#if AT86RF2XX_HAVE_RETRIES
+ISR(TRX24_TX_START_vect){
+    /* __enter_isr(); is not neccessary as there is nothing which causes a
+     * thread_yield and the interrupt can not be interrupted by an other ISR */
+
+    at86rf2xx_t *dev = (at86rf2xx_t *) at86rfmega_dev;
+
+    dev->tx_retries++;
+}
+#endif
+
 /**
  * @brief ISR for transceiver's receive end interrupt
  *

drivers/at86rf2xx/include/at86rf2xx_registers.h

@@ -87,6 +87,9 @@ extern "C" {
 #define AT86RF2XX_REG__TRX_RPC                                  (&TRX_RPC)
 #define AT86RF2XX_REG__ANT_DIV                                  (&ANT_DIV)
 #define AT86RF2XX_REG__IRQ_MASK                                 (&IRQ_MASK)
+#ifdef IRQ_MASK1
+#define AT86RF2XX_REG__IRQ_MASK1                                (&IRQ_MASK1)
+#endif
 #define AT86RF2XX_REG__IRQ_STATUS                               (&IRQ_STATUS)
 #define AT86RF2XX_REG__IRQ_STATUS1                              (&IRQ_STATUS1)
 #define AT86RF2XX_REG__VREG_CTRL                                (&VREG_CTRL)

drivers/include/at86rf2xx.h

@@ -120,7 +120,7 @@ extern "C" {
 #   define MIN_RX_SENSITIVITY              (-101)
 #endif
 
-#if defined(DOXYGEN) || defined(MODULE_AT86RF232) || defined(MODULE_AT86RF233)
+#if defined(DOXYGEN) || defined(MODULE_AT86RF232) || defined(MODULE_AT86RF233) || defined(MODULE_AT86RFR2)
 /**
  * @brief   Frame retry counter reporting
  *
@@ -284,7 +284,7 @@ typedef struct {
                                              return to @ref at86rf2xx_t::idle_state */
 #if AT86RF2XX_HAVE_RETRIES
     /* Only radios with the XAH_CTRL_2 register support frame retry reporting */
-    uint8_t tx_retries;                 /**< Number of NOACK retransmissions */
+    int8_t tx_retries;                  /**< Number of NOACK retransmissions */
 #endif
     /** @} */
 } at86rf2xx_t;
@@ -619,7 +619,7 @@ size_t at86rf2xx_tx_load(at86rf2xx_t *dev, const uint8_t *data,
  *
  * @param[in] dev           device to trigger
  */
-void at86rf2xx_tx_exec(const at86rf2xx_t *dev);
+void at86rf2xx_tx_exec(at86rf2xx_t *dev);
 
 /**
  * @brief   Perform one manual channel clear assessment (CCA)