nimble/ll: Add debug printf vs hci event

This adds helper to send vs hci event with payload formatted in
printf-like manner. This shall not be used in any publicly available
code, it's only intended for local debugging purposes.

nimble/controller/include/controller/ble_ll_ctrl.h

@@ -335,6 +335,7 @@ void ble_ll_calc_session_key(struct ble_ll_conn_sm *connsm);
 void ble_ll_ctrl_phy_update_proc_complete(struct ble_ll_conn_sm *connsm);
 void ble_ll_ctrl_initiate_dle(struct ble_ll_conn_sm *connsm, bool initial);
 void ble_ll_hci_ev_send_vs_assert(const char *file, uint32_t line);
+void ble_ll_hci_ev_send_vs_printf(uint8_t id, const char *fmt, ...);
 void ble_ll_hci_ev_send_vs_llcp_trace(uint8_t type, uint16_t handle, uint16_t count,
                                       void *pdu, size_t length);
 

nimble/controller/src/ble_ll_hci_ev.c

@@ -16,8 +16,11 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-#include <stdint.h>
+
 #include <assert.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 #include "syscfg/syscfg.h"
 #include "nimble/ble.h"
@@ -609,6 +612,32 @@ ble_ll_hci_ev_send_vs_assert(const char *file, uint32_t line)
     }
 }
 
+void
+ble_ll_hci_ev_send_vs_printf(uint8_t id, const char *fmt, ...)
+{
+    struct ble_hci_ev_vs *ev;
+    struct ble_hci_ev *hci_ev;
+    va_list ap;
+
+    hci_ev = ble_transport_alloc_evt(1);
+    if (!hci_ev) {
+        return;
+    }
+
+    hci_ev->opcode = BLE_HCI_EVCODE_VS;
+    hci_ev->length = sizeof(*ev);
+
+    ev = (void *) hci_ev->data;
+    ev->id = id;
+
+    va_start(ap, fmt);
+    hci_ev->length += vsnprintf((void *)ev->data,
+                                BLE_HCI_MAX_DATA_LEN - sizeof(*ev), fmt, ap);
+    va_end(ap);
+
+    ble_ll_hci_event_send(hci_ev);
+}
+
 #if MYNEWT_VAL(BLE_LL_HCI_LLCP_TRACE)
 void
 ble_ll_hci_ev_send_vs_llcp_trace(uint8_t type, uint16_t handle, uint16_t count,