add device check in register function, which is provided by Rob <rdent@iinet.net.au>.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2355 bbd45198-f89e-11dd-88c7-29a3b14d5316

src/device.c

@@ -11,6 +11,8 @@
  * Date           Author       Notes
  * 2007-01-21     Bernard      the first version
  * 2010-05-04     Bernard      add rt_device_init implementation
+ * 2012-10-20     Bernard      add device check in register function, 
+ *                             provided by Rob <rdent@iinet.net.au>
  */
 
 #include <rtthread.h>
@@ -31,12 +33,15 @@ rt_err_t rt_device_register(rt_device_t dev, const char *name, rt_uint16_t flags
 	if (dev == RT_NULL)
 		return -RT_ERROR;
 
+	if (rt_device_find(name) != RT_NULL) 
+		return -RT_ERROR;
+
 	rt_object_init(&(dev->parent), RT_Object_Class_Device, name);
 	dev->flag = flags;
 
 	return RT_EOK;
 }
-RTM_EXPORT(rt_device_register);
+RTM_EXPORT(rt_device_register);
 
 /**
  * This function removes a previously registered device driver
@@ -53,7 +58,7 @@ rt_err_t rt_device_unregister(rt_device_t dev)
 
 	return RT_EOK;
 }
-RTM_EXPORT(rt_device_unregister);
+RTM_EXPORT(rt_device_unregister);
 
 /**
  * This function initializes all registered device driver
@@ -138,7 +143,7 @@ rt_device_t rt_device_find(const char *name)
 	/* not found */
 	return RT_NULL;
 }
-RTM_EXPORT(rt_device_find);
+RTM_EXPORT(rt_device_find);
 
 /**
  * This function will initialize the specified device
@@ -198,18 +203,19 @@ rt_err_t rt_device_open(rt_device_t dev, rt_uint16_t oflag)
 	/* if device is not initialized, initialize it. */
 	if (!(dev->flag & RT_DEVICE_FLAG_ACTIVATED))
 	{
-		result = dev->init(dev);
-		if (result != RT_EOK)
+		if (dev->init != RT_NULL )
 		{
-			rt_kprintf("To initialize device:%s failed. The error code is %d\n",
-				dev->parent.name, result);
+			result = dev->init(dev);
+			if (result != RT_EOK)
+			{
+				rt_kprintf("To initialize device:%s failed. The error code is %d\n",
+					dev->parent.name, result);
 
-			return result;
-		}
-		else
-		{
-			dev->flag |= RT_DEVICE_FLAG_ACTIVATED;
+				return result;
+			}
 		}
+
+		dev->flag |= RT_DEVICE_FLAG_ACTIVATED;
 	}
 
 	/* device is a stand alone device and opened */
@@ -225,7 +231,7 @@ rt_err_t rt_device_open(rt_device_t dev, rt_uint16_t oflag)
 	else
 	{
 		/* no this interface in device driver */
-		result = -RT_ENOSYS;
+		/* result = -RT_ENOSYS; not set errno */
 	}
 
 	/* set open flag */
@@ -234,7 +240,7 @@ rt_err_t rt_device_open(rt_device_t dev, rt_uint16_t oflag)
 
 	return result;
 }
-RTM_EXPORT(rt_device_open);
+RTM_EXPORT(rt_device_open);
 
 /**
  * This function will close a device
@@ -259,7 +265,7 @@ rt_err_t rt_device_close(rt_device_t dev)
 	else
 	{
 		/* no this interface in device driver */
-		result = -RT_ENOSYS;
+		/* result = -RT_ENOSYS; not set errno */
 	}
 
 	/* set open flag */
@@ -268,7 +274,7 @@ rt_err_t rt_device_close(rt_device_t dev)
 
 	return result;
 }
-RTM_EXPORT(rt_device_close);
+RTM_EXPORT(rt_device_close);
 
 /**
  * This function will read some data from a device.
@@ -300,7 +306,7 @@ rt_size_t rt_device_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t
 
 	return 0;
 }
-RTM_EXPORT(rt_device_read);
+RTM_EXPORT(rt_device_read);
 
 /**
  * This function will write some data to a device.
@@ -332,7 +338,7 @@ rt_size_t rt_device_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_
 
 	return 0;
 }
-RTM_EXPORT(rt_device_write);
+RTM_EXPORT(rt_device_write);
 
 /**
  * This function will perform a variety of control functions on devices.
@@ -358,7 +364,7 @@ rt_err_t rt_device_control(rt_device_t dev, rt_uint8_t cmd, void *arg)
 
 	return -RT_ENOSYS;
 }
-RTM_EXPORT(rt_device_control);
+RTM_EXPORT(rt_device_control);
 
 /**
  * This function will set the indication callback function when device receives
@@ -377,7 +383,7 @@ rt_err_t rt_device_set_rx_indicate(rt_device_t dev, rt_err_t (*rx_ind)(rt_device
 
 	return RT_EOK;
 }
-RTM_EXPORT(rt_device_set_rx_indicate);
+RTM_EXPORT(rt_device_set_rx_indicate);
 
 /**
  * This function will set the indication callback function when device has written
@@ -396,6 +402,6 @@ rt_err_t rt_device_set_tx_complete(rt_device_t dev, rt_err_t (*tx_done)(rt_devic
 
 	return RT_EOK;
 }
-RTM_EXPORT(rt_device_set_tx_complete);
+RTM_EXPORT(rt_device_set_tx_complete);
 
 #endif