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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/device-tree/vas.rst | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/doc/device-tree/vas.rst b/doc/device-tree/vas.rst new file mode 100644 index 0000000..606f476 --- /dev/null +++ b/doc/device-tree/vas.rst @@ -0,0 +1,28 @@ +Virtual Accelerator Switchboard (VAS) +==================================== + +VAS is present in P9 or later processors. In P9, each chip has one +instance of VAS. Each instance of VAS is represented as a "platform +device" i.e as a node in root of the device tree: +:: + + /vas@<vas_addr> + +with unique VAS address which also represents the Hypervisor window +context address for the instance of VAS. + +Each VAS node contains: :: + + compatible: "ibm,power9-vas", "ibm,vas" + + ibm,vas-id: unique identifier for each instance of VAS in the system. + + reg: contains 8 64-bit fields. + + Fields [0] and [1] represent the Hypervisor window context BAR + (start and length). Fields [2] and [3] represent the OS/User + window context BAR (start and length). Fields [4] and [5] + contain the start and length of paste power bus address region + for this chip. Fields [6] and [7] represent the bit field (start + bit and number of bits) where the window id of the window should + be encoded when computing the paste address for the window. |