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Possible License(s): CC-BY-SA-3.0, GPL-2.0, LGPL-2.0, AGPL-1.0
1The SGI IOC4 PCI device is a bit of a strange beast, so some notes on 2it are in order. 3 4First, even though the IOC4 performs multiple functions, such as an 5IDE controller, a serial controller, a PS/2 keyboard/mouse controller, 6and an external interrupt mechanism, it's not implemented as a 7multifunction device. The consequence of this from a software 8standpoint is that all these functions share a single IRQ, and 9they can't all register to own the same PCI device ID. To make 10matters a bit worse, some of the register blocks (and even registers 11themselves) present in IOC4 are mixed-purpose between these several 12functions, meaning that there's no clear "owning" device driver. 13 14The solution is to organize the IOC4 driver into several independent 15drivers, "ioc4", "sgiioc4", and "ioc4_serial". Note that there is no 16PS/2 controller driver as this functionality has never been wired up 17on a shipping IO card. 18 19ioc4 20==== 21This is the core (or shim) driver for IOC4. It is responsible for 22initializing the basic functionality of the chip, and allocating 23the PCI resources that are shared between the IOC4 functions. 24 25This driver also provides registration functions that the other 26IOC4 drivers can call to make their presence known. Each driver 27needs to provide a probe and remove function, which are invoked 28by the core driver at appropriate times. The interface of these 29IOC4 function probe and remove operations isn't precisely the same 30as PCI device probe and remove operations, but is logically the 31same operation. 32 33sgiioc4 34======= 35This is the IDE driver for IOC4. Its name isn't very descriptive 36simply for historical reasons (it used to be the only IOC4 driver 37component). There's not much to say about it other than it hooks 38up to the ioc4 driver via the appropriate registration, probe, and 39remove functions. 40 41ioc4_serial 42=========== 43This is the serial driver for IOC4. There's not much to say about it 44other than it hooks up to the ioc4 driver via the appropriate registration, 45probe, and remove functions.