Direct access functions return errors directly, not touching errno.

src/drivers/device/device.cpp

@@ -223,31 +223,22 @@ 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;
+	return -ENODEV;
 }
 
 int
 Device::write(unsigned offset, void *data, unsigned count)
 {
-	errno = ENODEV;
-	return -1;
+	return -ENODEV;
 }
 
 int
 Device::ioctl(unsigned operation, unsigned &arg)
 {
-	errno = ENODEV;
-	return -1;
+	return -ENODEV;
 }
 
 } // namespace device

src/drivers/device/device.h

@@ -85,11 +85,11 @@ public:
 	 */
 
 	/**
-	  * Probe to test whether the device is present.
+	 * Initialise the driver and make it ready for use.
 	 *
-	  * @return		Zero if present, < 0 (error) otherwise.
+	 * @return	OK if the driver initialized OK, negative errno otherwise;
 	 */
-	 virtual int	probe();
+	virtual int	init();
 
 	/**
 	 * Read directly from the device.
@@ -98,10 +98,10 @@ public:
 	 *
 	 * @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.
+	 * @param count		The number of items to read.
+	 * @return		The number of items read on success, negative errno otherwise.
 	 */
-	 virtual int	read(unsigned address, void *data, unsigned count = 1);
+	virtual int	read(unsigned address, void *data, unsigned count);
 
 	/**
 	 * Write directly to the device.
@@ -110,17 +110,17 @@ public:
 	 *
 	 * @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.
+	 * @param count		The number of items to write.
+	 * @return		The number of items written on success, negative errno otherwise.
 	 */	 
-	 virtual int	write(unsigned address, void *data, unsigned count = 1);
+	virtual int	write(unsigned address, void *data, unsigned count);
 
 	/**
 	 * Perform a device-specific operation.
 	 *
-	  * @param operation	The operation to perform
+	 * @param operation	The operation to perform.
 	 * @param arg		An argument to the operation.
-	  * @return		< 0 on error
+	 * @return		Negative errno on error, OK or positive value on success.
 	 */
 	virtual int	ioctl(unsigned operation, unsigned &arg);
 
@@ -137,13 +137,6 @@ protected:
 	Device(const char *name,
 	       int irq = 0);
 
-	/**
-	 * Initialise the driver and make it ready for use.
-	 *
-	 * @return	OK if the driver initialised OK.
-	 */
-	virtual int	init();
-
 	/**
 	 * Enable the device interrupt
 	 */