Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) # SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) config NTB_IDT
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) 	tristate "IDT PCIe-switch Non-Transparent Bridge support"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) 	depends on PCI
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 	select HWMON
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 	help
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 	 This driver supports NTB of capable IDT PCIe-switches.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 	 Some of the pre-initializations must be made before IDT PCIe-switch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 	 exposes its NT-functions correctly. It should be done by either proper
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 	 initialization of EEPROM connected to master SMbus of the switch or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 	 by BIOS using slave-SMBus interface changing corresponding registers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 	 value. Evidently it must be done before PCI bus enumeration is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 	 finished in Linux kernel.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 	 First of all partitions must be activated and properly assigned to all
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	 the ports with NT-functions intended to be activated (see SWPARTxCTL
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	 and SWPORTxCTL registers). Then all NT-function BARs must be enabled
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	 with chosen valid aperture. For memory windows related BARs the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 	 aperture settings shall determine the maximum size of memory windows
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	 accepted by a BAR. Note that BAR0 must map PCI configuration space
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	 registers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	 It's worth to note, that since a part of this driver relies on the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	 BAR settings of peer NT-functions, the BAR setups can't be done over
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 	 kernel PCI fixups. That's why the alternative pre-initialization
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 	 techniques like BIOS using SMBus interface or EEPROM should be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 	 utilized.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 	 If unsure, say N.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)