jmr3927 « mips « arch - litmus-rt.git

The LITMUS^RT kernel.

Bjoern Brandenburg

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ly. In the event a driver is not bound to the device, it can be enabled using the 'enable' file, documented above. The 'remove' file is used to remove the PCI device, by writing a non-zero integer to the file. This does not involve any kind of hot-plug functionality, e.g. powering off the device. The device is removed from the kernel's list of PCI devices, the sysfs directory for it is removed, and the device will be removed from any drivers attached to it. Removal of PCI root buses is disallowed. Accessing legacy resources through sysfs ---------------------------------------- Legacy I/O port and ISA memory resources are also provided in sysfs if the underlying platform supports them. They're located in the PCI class hierarchy, e.g. /sys/class/pci_bus/0000:17/ |-- bridge -> ../../../devices/pci0000:17 |-- cpuaffinity |-- legacy_io `-- legacy_mem The legacy_io file is a read/write file that can be used by applications to do legacy port I/O. The application should open the file, seek to the desired port (e.g. 0x3e8) and do a read or a write of 1, 2 or 4 bytes. The legacy_mem file should be mmapped with an offset corresponding to the memory offset desired, e.g. 0xa0000 for the VGA frame buffer. The application can then simply dereference the returned pointer (after checking for errors of course) to access legacy memory space. Supporting PCI access on new platforms -------------------------------------- In order to support PCI resource mapping as described above, Linux platform code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function. Platforms are free to only support subsets of the mmap functionality, but useful return codes should be provided. Legacy resources are protected by the HAVE_PCI_LEGACY define. Platforms wishing to support legacy functionality should define it and provide pci_legacy_read, pci_legacy_write and pci_mmap_legacy_page_range functions.