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diff --git a/Documentation/ntb.txt b/Documentation/ntb.txt new file mode 100644 index 000000000000..9d46dc9712a8 --- /dev/null +++ b/Documentation/ntb.txt @@ -0,0 +1,32 @@ +# NTB Drivers + +NTB (Non-Transparent Bridge) is a type of PCI-Express bridge chip that connects +the separate memory systems of two computers to the same PCI-Express fabric. +Existing NTB hardware supports a common feature set, including scratchpad +registers, doorbell registers, and memory translation windows. Scratchpad +registers are read-and-writable registers that are accessible from either side +of the device, so that peers can exchange a small amount of information at a +fixed address. Doorbell registers provide a way for peers to send interrupt +events. Memory windows allow translated read and write access to the peer +memory. + +## NTB Core Driver (ntb) + +The NTB core driver defines an api wrapping the common feature set, and allows +clients interested in NTB features to discover NTB the devices supported by +hardware drivers. The term "client" is used here to mean an upper layer +component making use of the NTB api. The term "driver," or "hardware driver," +is used here to mean a driver for a specific vendor and model of NTB hardware. + +## NTB Client Drivers + +NTB client drivers should register with the NTB core driver. After +registering, the client probe and remove functions will be called appropriately +as ntb hardware, or hardware drivers, are inserted and removed. The +registration uses the Linux Device framework, so it should feel familiar to +anyone who has written a pci driver. + +## NTB Hardware Drivers + +NTB hardware drivers should register devices with the NTB core driver. After +registering, clients probe and remove functions will be called. |