OXMPCI952 Datasheet, PDF (52/108 Pages) Oxford Semiconductor – Integrated High Performance Dual UARTs, 8-bit Local Bus/Parallel Port. 3.3v PCI/miniPCI interface.

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(Software drivers should keep a copy of the contents of the ACR elsewhere since reading ICR involves overwriting ACR!)
Write the desired offset to SPR (address 111b).
Read the desired value from ICR (address 101b).
Write 0x00 offset to SPR to select ACR.
Clear bit 6 of ACR bye writing x0xxxxxxb to ICR, thus enabling access to standard registers again.
OXmPCI952
DS-0020 Jun 05
Page 52