Method and Apparatus for Intercommunications Amongst Device Drivers

• US 20080168475A1
• Filed: 01/07/2007
• Published: 07/10/2008
• Est. Priority Date: 01/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Douglas, Simon, de Cesare, Joshua, Kosut, Alexei Elias
• Granted Patent: US 7,979,868 B2
• Time in Patent Office: Days
• US Class Current: 719/321
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers

Abstract

Techniques for intercommunication amongst device drivers are described herein. In one embodiment, an application programming interface (API) is provided by a kernel of an operating system (OS) running within a data processing system. The API is accessible by device drivers associated with multiple devices installed in the system. In response to a request from a first instance of a driver via the API, information indicating whether another instance of the same driver is currently started is returned via the API. Other methods and apparatuses are also described.

Claims

1. A machine-implemented method for managing device drivers of devices in a computer, the method comprising:

providing an application programming interface (API) within a kernel of an operating system (OS) running within a computer, the API being accessible by a plurality of device drivers associated with a plurality of devices in the computer; and

in response to a request from a first instance of a device driver via the API, returning information indicating whether a second instance of the device driver is currently loaded within the kernel.

2. The method of claim 1, wherein each of the plurality of devices is represented by a node of a device tree having a hierarchical structure, and wherein the API is maintained by a node that is a most top node in the device tree.

3. The method of claim 1, further comprising, in response to the request and as part of the API, accessing a data structure having a plurality entries corresponding to the plurality of devices in the computer, wherein each entry includes a first field to store an identifier of a corresponding device and a second field to store a handle of a device driver currently associated with the corresponding device.

4. The method of claim 3, further comprising acquiring a lock prior to accessing the data structure to prevent others from accessing the data structure and releasing the lock after accessing the data structure to allow others to access the data structure.

5. The method of claim 3, further comprising:

the API inserting a first handle of the first instance of the device driver in the second field of a corresponding device in the data structure if the second field is empty; and

the API returning a first handle of the first instance of the device driver.

6. The method of claim 5, further comprising starting the first instance of the device driver if the second field of the corresponding device is empty.

7. The method of claim 5, further comprising the API returning a second handle of the second instance of the device driver retrieved from the second field of the corresponding device if the second stance of the device driver is currently associated with the corresponding device.

8. The method of claim 7, further comprising unloading the first instance of the device driver if the second instance of the device driver is currently loaded.

9. The method of claim 3, wherein each of the plurality of devices is represented by a node of a device tree having a hierarchical structure, each being associated with a device driver, wherein the first instance of the device driver is associated with a first device node and the second instance of the device driver is associated with a second device node of the device tree, and wherein devices corresponding to the first and second device nodes are supported by the same device driver.

10. The method of claim 9, wherein the first device node includes a property attribute to store a first identifier of a device corresponding to the first device node and the second device node includes a property attribute to store a second identifier of a device corresponding to the second device node, and wherein the first and second identifiers are used by the API to determine which of the first and second instances of the device driver is loaded.

11. The method of claim 10, wherein the first and second identifiers are identical and unique in the device tree, which indicates that the first and second device nodes are supported by the same device driver.

12. A machine-readable medium having instructions stored herein, which when executed by a computer, cause a machine to perform a method, the method comprising:

providing an application programming interface (API) within a kernel of an operating system (OS) running within a computer, the API being accessible by a plurality of device drivers associated with a plurality of devices in the computer; and

in response to a request from a first instance of a device driver via the API, returning information indicating whether a second instance of the device driver is currently loaded within the kernel.

13. The machine-readable medium of claim 12, wherein each of the plurality of devices is represented by a node of a device tree having a hierarchical structure, and wherein the API is maintained by a node that is a most top node in the device tree.

14. The machine-readable medium of claim 12, wherein the method further comprises, in response to the request and as part of the API, accessing a data structure having a plurality entries corresponding to the plurality of devices in the computer, wherein each entry includes a first field to store an identifier of a corresponding device and a second field to store a handle of a device driver currently associated with the corresponding device.

15. The machine-readable medium of claim 14, wherein the method further comprises acquiring a lock prior to accessing the data structure to prevent others from accessing the data structure and releasing the lock after accessing the data structure to allow others to access the data structure.

16. The machine-readable medium of claim 14, wherein the method further comprises:

the API inserting a first handle of the first instance of the device driver in the second field of a corresponding device in the data structure if the second field is empty; and

the API returning a first handle of the first instance of the device driver.

17. The machine-readable medium of claim 16, wherein the method further comprises starting the first instance of the device driver if the second field of the corresponding device is empty.

18. The machine-readable medium of claim 16, wherein the method further comprises the API returning a second handle of the second instance of the device driver retrieved from the second field of the corresponding device if the second stance of the device driver is currently associated with the corresponding device.

19. The machine-readable medium of claim 18, wherein the method further comprises unloading the first instance of the device driver if the second instance of the device driver is currently loaded.

20. The machine-readable medium of claim 14, wherein each of the plurality of devices is represented by a node of a device tree having a hierarchical structure, each being associated with a device driver, wherein the first instance of the device driver is associated with a first device node and the second instance of the device driver is associated with a second device node of the device tree, and wherein devices corresponding to the first and second device nodes are supported by the same device driver.

21. The machine-readable medium of claim 20, wherein the first device node includes a property attribute to store a first identifier of a device corresponding to the first device node and the second device node includes a property attribute to store a second identifier of a device corresponding to the second device node, and wherein the first and second identifiers are used by the API to determine which of the first and second instances of the device driver is loaded.

22. The machine-readable medium of claim 21, wherein the first and second identifiers are identical and unique in the device tree, which indicates that the first and second device nodes are supported by the same device driver.

23. An apparatus for managing device drivers of devices in a computer, the method comprising:

means for providing an application programming interface (API) within a kernel of an operating system (OS) running within a computer, the API being accessible by a plurality of device drivers associated with a plurality of devices in the computer; and

in response to a request from a first instance of a device driver via the API, means for returning information indicating whether a second instance of the device driver is currently loaded within the kernel.

25. The architecture of claim 23, wherein the API is invoked during an initialization of the instance of the device driver.

26. The architecture of claim 23, further comprising a device map maintained by the kernel, the device map having a plurality of entries and each corresponding to a device, wherein the device map is accessible by the kernel as part of the API to determine whether an instance of a device driver for a particular device is loaded.

27. The architecture of claim 25, wherein the device map includes a first field to store an identifier of a corresponding device and a second field to store a driver handle of a device driver associated with the corresponding device.

28. The architecture of claim 26, wherein the API returns a driver handle of an existing driver specified in a second field of a device, indicating that the existing driver has been loaded.

24. A computer system architecture, comprising:

a plurality of device drivers loaded in a kernel of an operating system of a computer, each of the device drivers corresponding to a device presented in the computer; and

an application programming interface (API) for coupling the kernel with the plurality of device drivers, the API enabling an instance of a device driver to communicate with the kernel to determine whether another instance of the device driver is currently loaded.

29. A computer implemented method, comprising:

a first instance of a diver calling an application programming interface (API) maintained by a kernel of an operating system, the first instance of the driver being identified via a first driver identifier; and

in response to a result of calling the API, the first instance of the driver determining whether a second instance of the driver has been initialized.

30. The method of claim 29, further comprising examining a second driver identifier returned by the API to determine whether the first and second driver identifiers are identical.

31. The method of claim 30, further comprising:

starting the first instance of the driver if the first and second driver identifiers are identical; and

unloading the first instance of the driver if the first and second driver identifiers are different.

32. A machine-readable medium having instructions stored therein, which when executed by a machine, cause a machine to perform a method, the method comprising:

a first instance of a driver calling an application programming interface (API) maintained by a kernel of an operating system, the first instance of the driver being identified via a first driver identifier; and

in response to a result of calling the API, the first instance of the driver determining whether a second instance of the driver has been initialized.

33. The machine-readable medium of claim 32, wherein the method further comprises examining a second driver identifier returned by the API to determine whether the first and second driver identifiers are identical.

34. The machine-readable medium of claim 33, wherein the method further comprises:

starting the first instance of the driver if the first and second driver identifiers are identical; and

unloading the first instance of the driver if the first and second driver identifiers are different.

35. A machine implemented method, comprising:

in response to a request received from a first instance of a driver via an application program interface (API), determining whether a second instance of the driver for a device associated with the first instance of the driver has already been initialized, wherein the determination is performed based on information retrieved from a data structure having driver registration information; and

return a driver identifier to the first instance of the driver via the API, the driver identifier indicating whether a second instance of the driver has already been initialized.

36. The method of claim 35, further comprising:

performing a lookup operation within the data structure to determine whether a device identified by a device identifier extracted from the request is associated with a driver identifier; and

returning the driver identifier associated with the device to the first instance of the driver via the API, if the device has been associated with the driver identifier in the data structure.

37. The method of claim 36, further comprising:

inserting a driver identifier of the first instance into the data structure of the device has not been associated with any driver identifier; and

returning the driver identifier of the first instance to the first instance of the driver via the API.

38. A machine-readable medium having instructions stored therein, which when executed, cause a machine to perform a method, the method comprising:

in response to a request received from a first instance of a driver via an application program interface (API), determining whether a second instance of the driver for a device associated with the first instance of the driver has already been initialized, wherein the determination is performed based on information retrieved from a data structure having driver registration information; and

return a driver identifier to the first instance of the driver via the API, the driver identifier indicating whether a second instance of the driver has already been initialized.

39. The machine-readable medium of claim 38, wherein the method further comprises:

performing a lookup operation within the data structure to determine whether a device identified by a device identifier extracted from the request is associated with a driver identifier; and

returning the driver identifier associated with the device to the first instance of the driver via the API, if the device has been associated with the driver identifier in the data structure.

40. The machine-readable medium of claim 39, wherein the method further comprises:

inserting a driver identifier of the first instance into the data structure of the device has not been associated with any driver identifier; and

returning the driver identifier of the first instance to the first instance of the driver via the API.

41. A machine-implemented method for managing device drivers of devices in a computer, the method comprising:

providing an application programming interface (API) within an operating system (OS) running within a computer, the API being accessible by a plurality of device drivers associated with a plurality of devices in the computer; and

in response to a request from a first instance of a device driver via the API, returning information indicating whether a second instance of the device driver is currently loaded within the OS.

42. A machine-readable medium having a library to be loaded within an operating system of a computer, comprising:

an application programming interface (API) accessible by a plurality of device drivers associated with a plurality of devices in the computer,

wherein in response to a request from a first instance of a device driver via the API, the API is configured to return information indicating whether a second instance of the device driver is currently loaded within the OS.

43. The machine-readable medium of claim 42, wherein the library is a component of a kernel of the OS.