nimble/ll: Introduce Rx end early callback

This adds Rx end early callback that is called before scheduled
PHY transition. This allows user to e.g. prepare CCM for next Rx.

Author: MariuszSkamra

nimble/controller/include/controller/ble_ll.h

@@ -581,6 +581,9 @@ int ble_ll_rx_start(uint8_t *rxbuf, uint8_t chan, struct ble_mbuf_hdr *hdr);
 /* Called by the PHY when a packet reception ends */
 int ble_ll_rx_end(uint8_t *rxbuf, struct ble_mbuf_hdr *rxhdr);
 
+/* Called by the PHY when a packet reception ends */
+int ble_ll_rx_early_end(const uint8_t *rxbuf, const struct ble_mbuf_hdr *rxhdr);
+
 /* Helper callback to tx mbuf using ble_phy_tx() */
 uint8_t ble_ll_tx_mbuf_pducb(uint8_t *dptr, void *pducb_arg, uint8_t *hdr_byte);
 uint8_t ble_ll_tx_flat_mbuf_pducb(uint8_t *dptr, void *pducb_arg, uint8_t *hdr_byte);

nimble/controller/src/ble_ll.c

@@ -1305,6 +1305,30 @@ ble_ll_rx_end(uint8_t *rxbuf, struct ble_mbuf_hdr *rxhdr)
     return rc;
 }
 
+/**
+ * Early callback called by the PHY when a packet reception has ended.
+ *
+ * NOTE: Called from interrupt context!
+ *       Avoid time-consuming operations, such as buffer copying or memory allocation.
+ *
+ * @param rxbuf Pointer to received PDU data
+ *        rxhdr Pointer to BLE header of received mbuf
+ *
+ * @return int
+ *       < 0: Disable the phy after reception.
+ *      == 0: Success. Do not disable the PHY.
+ *       > 0: Do not disable PHY as that has already been done.
+ */
+int
+ble_ll_rx_early_end(const uint8_t *rxbuf, const struct ble_mbuf_hdr *rxhdr)
+{
+    int rc = 0;
+
+    /* TODO */
+
+    return rc;
+}
+
 uint8_t
 ble_ll_tx_mbuf_pducb(uint8_t *dptr, void *pducb_arg, uint8_t *hdr_byte)
 {

nimble/drivers/nrf5x/src/ble_phy.c

@@ -1359,6 +1359,19 @@ ble_phy_rx_end_isr(void)
 #endif
     }
 
+    /*
+     * XXX: This is a horrible ugly hack to deal with the RAM S1 byte
+     * that is not sent over the air but is present here. Simply move the
+     * data pointer to deal with it. Fix this later.
+     */
+    dptr[2] = dptr[1];
+    dptr[1] = dptr[0];
+    rc = ble_ll_rx_early_end(dptr + 1, ble_hdr);
+    if (rc < 0) {
+        ble_phy_disable();
+        return;
+    }
+
     /*
      * Let's schedule TX now and we will just cancel it after processing RXed
      * packet if we don't need TX.
@@ -1385,13 +1398,6 @@ ble_phy_rx_end_isr(void)
 
     ble_phy_transition_set(BLE_PHY_TRANSITION_NONE, 0);
 
-    /*
-     * XXX: This is a horrible ugly hack to deal with the RAM S1 byte
-     * that is not sent over the air but is present here. Simply move the
-     * data pointer to deal with it. Fix this later.
-     */
-    dptr[2] = dptr[1];
-    dptr[1] = dptr[0];
     rc = ble_ll_rx_end(dptr + 1, ble_hdr);
     if (rc < 0) {
         ble_phy_disable();