74 lines
2.2 KiB
ReStructuredText
74 lines
2.2 KiB
ReStructuredText
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XSCOM Bindings
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==============
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XSCOM regions
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-------------
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The top-level xscom nodes specify the mapping range from the 64-bit address
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space into the PCB address space.
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There's one mapping range per chip xscom, therefore one node per mapping range.
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::
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/
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/xscom@<chip-base-address-0>/
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/xscom@<chip-base-address-1>/
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…
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/xscom@<chip-base-address-n>/
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* where <chip-base-address-n> is the xscom base address with the gcid-specific
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bits (for chip n) OR-ed in.
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Each xscom node has the following properties:
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* #address-cells = 1
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* #size-cells = 1
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* reg = <base-address[#parent-address-cells] size[#parent-size-cells]>
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* ibm,chip-id = gcid
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* compatible = "ibm,xscom", "ibm,power8-scom" / "ibm,power7-xscom"
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* ecid = <Electronic Chip ID, applicable for POWER9 onwards>
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* wafer-id = <wafer ID, applicable for POWER9 onwards>
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* wafer-location = <wafer location, applicable for POWER9 onwards>
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ECID
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----
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Electronic Chip ID (ECID) is a process by which the wafer number, chip location
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(i.e. X,Y) and other optional data items are electrically encoded directly on
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the chip. wafer-id property represents wafer number and wafer-location property
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represents chip location (both X and Y location).
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Chiplet endpoints
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-----------------
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One sub-node per endpoint. Endpoints are defined by their (port,
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endpoint-address) data on the PCB, and are named according to their endpoint
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types:
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::
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/xscom@<chip-base-address>/
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/xscom@<chip-base-address>/chiptod@<endpoint-addr>
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/xscom@<chip-base-address>/lpc@<endpoint-addr>
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* where the <endpoint-addr> is a single address (as distinct from the current
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(gcid,base) format), consisting of the SCOM port and SCOM endpoint bits in
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their 31-bit address format.
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Each endpoint node has the following properties:
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* reg = <endpoint-address[#parent-address-cells] size[#parent-size-cells]>
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* compatible - depends on endpoint type, eg "ibm,power8-chiptod"
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The endpoint address specifies the address on the PCB. So, to calculate the
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MMIO address for a PCB register:
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::
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mmio_addr = <xscom-base-addr> | (pcb_addr[1:27] << 4)
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| (pcb_addr[28:31] << 3)
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Where:
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* xscom-base-addr is the address from the first two cells of the parent
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node's reg property
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* pcb_addr is the first cell of the endpoint's reg property
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