1# SPDX-License-Identifier: GPL-2.0-only
2config NTB_IDT
3	tristate "IDT PCIe-switch Non-Transparent Bridge support"
4	depends on PCI
5	select HWMON
6	help
7	 This driver supports NTB of capable IDT PCIe-switches.
8
9	 Some of the pre-initializations must be made before IDT PCIe-switch
10	 exposes its NT-functions correctly. It should be done by either proper
11	 initialization of EEPROM connected to master SMbus of the switch or
12	 by BIOS using slave-SMBus interface changing corresponding registers
13	 value. Evidently it must be done before PCI bus enumeration is
14	 finished in Linux kernel.
15
16	 First of all partitions must be activated and properly assigned to all
17	 the ports with NT-functions intended to be activated (see SWPARTxCTL
18	 and SWPORTxCTL registers). Then all NT-function BARs must be enabled
19	 with chosen valid aperture. For memory windows related BARs the
20	 aperture settings shall determine the maximum size of memory windows
21	 accepted by a BAR. Note that BAR0 must map PCI configuration space
22	 registers.
23
24	 It's worth to note, that since a part of this driver relies on the
25	 BAR settings of peer NT-functions, the BAR setups can't be done over
26	 kernel PCI fixups. That's why the alternative pre-initialization
27	 techniques like BIOS using SMBus interface or EEPROM should be
28	 utilized.
29
30	 If unsure, say N.
31
32