externals/nrf52: Fix bug that multiple API executions do not work well

APIs are executed in multi-thread and the timings match,
the late API thread keep running forever and the preceding
API tasks freezes.
Fix the bug by introducing lock and unlock with mutex and
condition variable of pthread.

externals/nrf52/nRF5_SDK_17.1.0_ddde560/components/serialization/application/transport/ser_sd_transport.c

@@ -40,6 +40,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stddef.h>
+#include <pthread.h>
 #include "ser_sd_transport.h"
 #include "ser_hal_transport.h"
 #include "nrf_error.h"
@@ -85,6 +86,8 @@ static ser_sd_transport_rsp_handler_t m_rsp_dec_handler = NULL;
 
 /** Flag indicated whether module is waiting for response packet. */
 static volatile bool m_rsp_wait = false;
+static pthread_mutex_t m_mutex_rsp_wait;
+static pthread_cond_t  m_cond_rsp_wait;
 
 /** SoftDevice call return value decoded by user decoder handler. */
 static uint32_t m_return_value;
@@ -213,6 +216,9 @@ uint32_t ser_sd_transport_open(ser_sd_transport_evt_handler_t             ble_ev
                                ser_sd_transport_rsp_set_handler_t         os_rsp_set_handler,
                                ser_sd_transport_rx_notification_handler_t rx_not_handler)
 {
+    pthread_mutex_init(&m_mutex_rsp_wait, NULL);
+    pthread_cond_init(&m_cond_rsp_wait, NULL);
+
     m_os_rsp_wait_handler = os_rsp_wait_handler;
     m_os_rsp_set_handler  = os_rsp_set_handler;
     m_rx_notify_handler   = rx_not_handler;
@@ -259,6 +265,9 @@ uint32_t ser_sd_transport_close(void)
 
     ser_hal_transport_close();
 
+    pthread_cond_destroy(&m_cond_rsp_wait);
+    pthread_mutex_destroy(&m_mutex_rsp_wait);
+
     return NRF_SUCCESS;
 }
 
@@ -278,6 +287,8 @@ uint32_t ser_sd_transport_tx_alloc(uint8_t * * pp_data, uint16_t * p_len)
 {
     uint32_t err_code;
 
+    pthread_mutex_lock(&m_mutex_rsp_wait);
+
     if (m_rsp_wait)
     {
         err_code = NRF_ERROR_BUSY;
@@ -286,6 +297,13 @@ uint32_t ser_sd_transport_tx_alloc(uint8_t * * pp_data, uint16_t * p_len)
     {
         err_code = ser_hal_transport_tx_pkt_alloc(pp_data, p_len);
     }
+
+    if ((err_code == NRF_ERROR_BUSY) || (err_code == NRF_ERROR_NO_MEM))
+    {
+        pthread_cond_wait(&m_cond_rsp_wait, &m_mutex_rsp_wait);
+    }
+
+    pthread_mutex_unlock(&m_mutex_rsp_wait);
     return err_code;
 }
 
@@ -306,6 +324,7 @@ uint32_t ser_sd_transport_cmd_write(const uint8_t *                p_buffer,
 {
     uint32_t err_code = NRF_SUCCESS;
 
+    pthread_mutex_lock(&m_mutex_rsp_wait);
     m_rsp_wait        = true;
     m_rsp_dec_handler = cmd_rsp_decode_callback;
     err_code          = ser_hal_transport_tx_pkt_send(p_buffer, length);
@@ -335,6 +354,9 @@ uint32_t ser_sd_transport_cmd_write(const uint8_t *                p_buffer,
         m_rsp_wait = false;
     }
 
+    pthread_cond_signal(&m_cond_rsp_wait);
+    pthread_mutex_unlock(&m_mutex_rsp_wait);
+
     NRF_LOG_DEBUG("[SD_CALL]:%lx, err_code= 0x%lX", (uint32_t)p_buffer[1], err_code);
     return err_code;
 }