Move the direct-access methods from CDev to Device… makes more sense that way.

src/drivers/device/cdev.cpp

@@ -395,25 +395,4 @@ cdev_poll(struct file *filp, struct pollfd *fds, bool setup)
 	return cdev->poll(filp, fds, setup);
 }
 
-int
-CDev::read(unsigned offset, void *data, unsigned count)
-{
-	errno = ENODEV;
-	return -1;
-}
-
-int
-CDev::write(unsigned offset, void *data, unsigned count)
-{
-	errno = ENODEV;
-	return -1;
-}
-
-int
-CDev::ioctl(unsigned operation, unsigned &arg)
-{
-	errno = ENODEV;
-	return -1;
-}
-
 } // namespace device

src/drivers/device/device.cpp

@@ -223,5 +223,31 @@ interrupt(int irq, void *context)
 	return OK;
 }
 
+int
+Device::probe()
+{
+	return -1;
+}
+
+int
+Device::read(unsigned offset, void *data, unsigned count)
+{
+	errno = ENODEV;
+	return -1;
+}
+
+int
+Device::write(unsigned offset, void *data, unsigned count)
+{
+	errno = ENODEV;
+	return -1;
+}
+
+int
+Device::ioctl(unsigned operation, unsigned &arg)
+{
+	errno = ENODEV;
+	return -1;
+}
 
 } // namespace device

src/drivers/device/device.h

@@ -68,11 +68,62 @@ namespace device __EXPORT
 class __EXPORT Device
 {
 public:
+	/**
+	 * Destructor.
+	 *
+	 * Public so that anonymous devices can be destroyed.
+	 */
+	virtual ~Device();
+
 	/**
 	 * Interrupt handler.
 	 */
 	virtual void	interrupt(void *ctx);	/**< interrupt handler */
 
+	 /*
+	  * Direct access methods.
+	  */
+
+	 /**
+	  * Probe to test whether the device is present.
+	  *
+	  * @return		Zero if present, < 0 (error) otherwise.
+	  */
+	 virtual int	probe();
+
+	 /**
+	  * Read directly from the device.
+	  *
+	  * The actual size of each unit quantity is device-specific.
+	  *
+	  * @param offset	The device address at which to start reading
+	  * @param data		The buffer into which the read values should be placed.
+	  * @param count		The number of items to read, defaults to 1.
+	  * @return		count on success, < 0 on error.
+	  */
+	 virtual int	read(unsigned address, void *data, unsigned count = 1);
+
+	 /**
+	  * Write directly to the device.
+	  *
+	  * The actual size of each unit quantity is device-specific.
+	  *
+	  * @param address	The device address at which to start writing.
+	  * @param data		The buffer from which values should be read.
+	  * @param count		The number of registers to write, defaults to 1.
+	  * @return		count on success, < 0 on error.
+	  */	 
+	 virtual int	write(unsigned address, void *data, unsigned count = 1);
+
+	 /**
+	  * Perform a device-specific operation.
+	  *
+	  * @param operation	The operation to perform
+	  * @param arg		An argument to the operation.
+	  * @return		< 0 on error
+	  */
+	 virtual int	ioctl(unsigned operation, unsigned &arg);
+
 protected:
 	const char	*_name;			/**< driver name */
 	bool		_debug_enabled;		/**< if true, debug messages are printed */
@@ -85,7 +136,6 @@ protected:
 	 */
 	Device(const char *name,
 	       int irq = 0);
-	virtual ~Device();
 
 	/**
 	 * Initialise the driver and make it ready for use.
@@ -282,48 +332,12 @@ public:
 	 * Test whether the device is currently open.
 	 *
 	 * This can be used to avoid tearing down a device that is still active.
+	 * Note - not virtual, cannot be overridden by a subclass.
 	 *
 	 * @return              True if the device is currently open.
 	 */
 	bool            is_open() { return _open_count > 0; }
 
-	/*
-	 * Direct access methods.
-	 */
-
-	/**
-	 * Read directly from the device.
-	 *
-	 * The actual size of each unit quantity is device-specific.
-	 *
-	 * @param offset	The device offset at which to start reading
-	 * @param data		The buffer into which the read values should be placed.
-	 * @param count		The number of items to read, defaults to 1.
-	 * @return		count on success, < 0 on error.
-	 */
-	virtual int	read(unsigned offset, void *data, unsigned count = 1);
-
-	/**
-	 * Write directly to the device.
-	 *
-	 * The actual size of each unit quantity is device-specific.
-	 *
-	 * @param address	The device address at which to start writing.
-	 * @param data		The buffer from which values should be read.
-	 * @param count		The number of registers to write, defaults to 1.
-	 * @return		count on success, < 0 on error.
-	 */	 
-	virtual int	write(unsigned address, void *data, unsigned count = 1);
-
-	/**
-	 * Perform a device-specific operation.
-	 *
-	 * @param operation	The operation to perform
-	 * @param arg		An argument to the operation.
-	 * @return		< 0 on error
-	 */
-	virtual int	ioctl(unsigned operation, unsigned &arg);
-
 protected:
 	/**
 	 * Pointer to the default cdev file operations table; useful for

src/drivers/device/i2c.h

@@ -55,13 +55,11 @@ class __EXPORT I2C : public CDev
 
 public:
 
-    /**
-     * Get the address
-     */
-    uint16_t get_address() {
-      return _address;
-    }
-
+	/**
+	 * Get the address
+	 */
+	int16_t		get_address() { return _address; }
+	
 protected:
 	/**
 	 * The number of times a read or write operation will be retried on