diff --git a/arch/arm/src/rtl8720c/ameba_flash.c b/arch/arm/src/rtl8720c/ameba_flash.c
index b49f5b09abf..ac6bd4dfc5e 100644
--- a/arch/arm/src/rtl8720c/ameba_flash.c
+++ b/arch/arm/src/rtl8720c/ameba_flash.c
@@ -30,6 +30,7 @@
 #include <nuttx/kmalloc.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/fs/partition.h>
+#include <nuttx/spinlock.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -131,6 +132,8 @@ static const struct partition_s ptable[5] =
   },
 };
 
+static spinlock_t g_lock = SP_UNLOCKED;
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -138,7 +141,7 @@ static const struct partition_s ptable[5] =
 static irqstate_t flash_resource_lock(void)
 {
   irqstate_t state;
-  state = enter_critical_section();
+  state = spin_lock_irqsave(&g_lock);
   icache_disable();
   dcache_disable();
   return state;
@@ -149,7 +152,7 @@ static void flash_resource_unlock(irqstate_t state)
   dcache_enable();
   icache_enable();
   icache_invalidate();
-  leave_critical_section(state);
+  spin_unlock_irqrestore(&g_lock, state);
 }
 
 static int ameba_flash_erase(struct mtd_dev_s *dev,
diff --git a/arch/arm/src/rtl8720c/ameba_uart.c b/arch/arm/src/rtl8720c/ameba_uart.c
index 0833dc22544..ab0a8488ac1 100644
--- a/arch/arm/src/rtl8720c/ameba_uart.c
+++ b/arch/arm/src/rtl8720c/ameba_uart.c
@@ -33,7 +33,7 @@
 #include <string.h>
 #include <errno.h>
 #include <debug.h>
-#include <nuttx/irq.h>
+#include <nuttx/spinlock.h>
 #include <nuttx/arch.h>
 #include <nuttx/serial/serial.h>
 #include <nuttx/fs/ioctl.h>
@@ -107,6 +107,7 @@ struct ameba_s
   bool                flow;      /* flow control (RTS/CTS) enabled */
 #endif
 #endif
+  spinlock_t          lock;      /* Ensure mutually exclusive access */
 };
 
 /****************************************************************************
@@ -213,6 +214,7 @@ static struct ameba_s g_uart0priv =
   .flow           = true,
 #endif
 #endif
+  .lock           = SP_UNLOCKED,
 };
 
 static uart_dev_t g_uart0port =
@@ -251,6 +253,7 @@ static struct ameba_s g_uart1priv =
   .flow           = true,
 #endif
 #endif
+  .lock           = SP_UNLOCKED,
 };
 
 static uart_dev_t g_uart1port =
@@ -289,6 +292,7 @@ static struct ameba_s g_uart2priv =
   .flow           = true,
 #endif
 #endif
+  .lock           = SP_UNLOCKED,
 };
 
 static uart_dev_t g_uart2port =
@@ -327,6 +331,7 @@ static struct ameba_s g_uart3priv =
   .flow           = true,
 #endif
 #endif
+  .lock           = SP_UNLOCKED,
 };
 
 static uart_dev_t g_uart3port =
@@ -753,7 +758,7 @@ static int ameba_ioctl(struct file *filep, int cmd, unsigned long arg)
           break;
         }
 
-      flags = enter_critical_section();
+      flags = spin_lock_irqsave(&priv->lock);
       cfsetispeed(termiosp, priv->baud);
       termiosp->c_cflag = ((priv->parity != 0) ? PARENB : 0) |
                           ((priv->parity == 1) ? PARODD : 0);
@@ -778,7 +783,7 @@ static int ameba_ioctl(struct file *filep, int cmd, unsigned long arg)
           break;
         }
 
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(&priv->lock, flags);
     }
 
     break;
@@ -792,7 +797,7 @@ static int ameba_ioctl(struct file *filep, int cmd, unsigned long arg)
           break;
         }
 
-      flags = enter_critical_section();
+      flags = spin_lock_irqsave(&priv->lock);
       switch (termiosp->c_cflag & CSIZE)
         {
         case CS5:
@@ -826,7 +831,7 @@ static int ameba_ioctl(struct file *filep, int cmd, unsigned long arg)
       priv->flow      = (termiosp->c_cflag & CRTSCTS) != 0;
 #endif
       ameba_setup(dev);
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(&priv->lock, flags);
     }
 
     break;
diff --git a/arch/arm/src/rtl8720c/ameba_wdt.c b/arch/arm/src/rtl8720c/ameba_wdt.c
index 7c68b3ab9fe..bc584cde58c 100644
--- a/arch/arm/src/rtl8720c/ameba_wdt.c
+++ b/arch/arm/src/rtl8720c/ameba_wdt.c
@@ -26,6 +26,7 @@
 
 #include <nuttx/config.h>
 #include <nuttx/arch.h>
+#include <nuttx/spinlock.h>
 #include <nuttx/timers/watchdog.h>
 #include <stdint.h>
 #include <sys/types.h>
@@ -53,6 +54,7 @@ struct ameba_lowerhalf_s
   bool     started;                 /* true: The watchdog timer has
                                      * been started
                                      */
+  spinlock_t lock;                  /* Ensure mutually exclusive access */
 };
 
 /****************************************************************************
@@ -113,11 +115,11 @@ static int ameba_start(struct watchdog_lowerhalf_s *lower)
 {
   struct ameba_lowerhalf_s *priv = (struct ameba_lowerhalf_s *)lower;
   irqstate_t flags;
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(&priv->lock);
   priv->started = true;
   priv->lastreset = clock_systime_ticks();
   hal_misc_wdt_enable();
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -140,12 +142,12 @@ static int ameba_stop(struct watchdog_lowerhalf_s *lower)
 {
   struct ameba_lowerhalf_s *priv = (struct ameba_lowerhalf_s *)lower;
   irqstate_t flags;
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(&priv->lock);
   hal_misc_wdt_disable();
   priv->started = false;
   priv->timeout = 0;
   priv->lastreset = 0;
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -176,10 +178,10 @@ static int ameba_keepalive(struct watchdog_lowerhalf_s *lower)
 
   /* Reload the WDT timer */
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(&priv->lock);
   priv->lastreset = clock_systime_ticks();
   hal_misc_wdt_refresh();
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -254,10 +256,10 @@ static int ameba_settimeout(struct watchdog_lowerhalf_s *lower,
 {
   struct ameba_lowerhalf_s *priv = (struct ameba_lowerhalf_s *)lower;
   irqstate_t flags;
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(&priv->lock);
   priv->timeout = timeout;
   hal_misc_wdt_init(timeout * 1000);
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -287,6 +289,7 @@ void ameba_wdt_initialize(void)
   /* Initialize the driver state structure. */
 
   priv->ops = &g_wdgops;
+  spin_lock_init(&priv->lock);
   watchdog_register(CONFIG_WATCHDOG_DEVPATH,
                     (struct watchdog_lowerhalf_s *)priv);
 }
diff --git a/arch/arm/src/rtl8720c/amebaz_depend.c b/arch/arm/src/rtl8720c/amebaz_depend.c
index 0e257061988..6ba9241ec4f 100644
--- a/arch/arm/src/rtl8720c/amebaz_depend.c
+++ b/arch/arm/src/rtl8720c/amebaz_depend.c
@@ -28,6 +28,7 @@
 #include <nuttx/mqueue.h>
 #include <nuttx/semaphore.h>
 #include <nuttx/signal.h>
+#include <nuttx/spinlock.h>
 #include <nuttx/syslog/syslog.h>
 
 /****************************************************************************
@@ -52,24 +53,23 @@ int __wrap_printf(const char *fmt, ...)
 
 /* stdio.h Wrapper End */
 
-static int uxcriticalnesting = 0;
+static rspinlock_t g_lock = RSPINLOCK_INITIALIZER;
+static irqstate_t g_flags = 0;
 
 /* Critical Operation Start */
 
 void save_and_cli(void)
 {
-  enter_critical_section();
-  uxcriticalnesting++;
+  irqstate_t flags = rspin_lock_irqsave(&g_lock);
+  if (!rspin_lock_is_recursive(&g_lock))
+    {
+      g_flags = flags;
+    }
 }
 
 void restore_flags(void)
 {
-  ASSERT(uxcriticalnesting);
-  uxcriticalnesting--;
-  if (uxcriticalnesting == 0)
-    {
-      leave_critical_section(0);
-    }
+  rspin_unlock_irqrestore(&g_lock, g_flags);
 }
 
 void rtw_enter_critical(void **plock, unsigned long *pirql)
@@ -871,21 +871,14 @@ uint32_t rtw_end_of_queue_search(struct list_head *head,
 
 /* Device lock Wrapper Start */
 
-static uint32_t mutex_init;
+static atomic_t mutex_init;
 static void *device_mutex[5];
 static void device_mutex_init(uint32_t device)
 {
   irqstate_t status;
-  if (!(mutex_init & (1 << device)))
+  if (atomic_fetch_or(&mutex_init, (1 << device)) & (1 << device) == 0)
     {
-      status = enter_critical_section();
-      if (!(mutex_init & (1 << device)))
-        {
-          rtw_mutex_init(&device_mutex[device]);
-          mutex_init |= (1 << device);
-        }
-
-      leave_critical_section(status);
+      rtw_mutex_init(&device_mutex[device]);
     }
 }
 
diff --git a/arch/arm/src/rtl8720c/amebaz_driver.h b/arch/arm/src/rtl8720c/amebaz_driver.h
index a7ff963941d..79bba355859 100644
--- a/arch/arm/src/rtl8720c/amebaz_driver.h
+++ b/arch/arm/src/rtl8720c/amebaz_driver.h
@@ -29,6 +29,7 @@
 
 #include <nuttx/config.h>
 #include <nuttx/semaphore.h>
+#include <nuttx/mutex.h>
 #include <nuttx/wdog.h>
 #include <nuttx/wqueue.h>
 #include <nuttx/net/netdev.h>
@@ -86,6 +87,7 @@ struct amebaz_dev_s
   rtw_scan_result_t         scan_data[AMEBAZ_SCAN_AP_COUNT];
   unsigned int scan_count;
   unsigned char             country[2];
+  mutex_t                   lock;
 };
 
 int amebaz_wl_start_scan(struct amebaz_dev_s *priv,
diff --git a/arch/arm/src/rtl8720c/amebaz_netdev.c b/arch/arm/src/rtl8720c/amebaz_netdev.c
index 9f136f5d90f..3fa58b7e6d5 100644
--- a/arch/arm/src/rtl8720c/amebaz_netdev.c
+++ b/arch/arm/src/rtl8720c/amebaz_netdev.c
@@ -296,14 +296,13 @@ static int amebaz_ifdown(struct net_driver_s *dev)
 {
   int ret = 0;
   struct amebaz_dev_s *priv = (struct amebaz_dev_s *)dev->d_private;
-  irqstate_t flags;
   if (priv->devnum == 0 && rltk_wlan_running(1))
     {
       printf("must ifdown wlan 1 first\r\n");
       return ERROR;
     }
 
-  flags = enter_critical_section();
+  nxmutex_lock(&priv->lock);
   if (IFF_IS_UP(dev->d_flags))
     {
       if (priv->curr)
@@ -333,7 +332,7 @@ static int amebaz_ifdown(struct net_driver_s *dev)
         }
     }
 
-  leave_critical_section(flags);
+  nxmutex_unlock(&priv->lock);
   return ret;
 }
 
@@ -343,6 +342,7 @@ int amebaz_netdev_register(struct amebaz_dev_s *priv)
   dev->d_ifup    = amebaz_ifup;
   dev->d_ifdown  = amebaz_ifdown;
   dev->d_txavail = amebaz_txavail;
+  nxmutex_init(priv->lock);
 #ifdef CONFIG_NETDEV_IOCTL
   dev->d_ioctl   = amebaz_ioctl;
 #endif