|  | # | 
|  | # PPS support configuration | 
|  | # | 
|  |  | 
|  | menu "PPS support" | 
|  |  | 
|  | config PPS | 
|  | tristate "PPS support" | 
|  | ---help--- | 
|  | PPS (Pulse Per Second) is a special pulse provided by some GPS | 
|  | antennae. Userland can use it to get a high-precision time | 
|  | reference. | 
|  |  | 
|  | Some antennae's PPS signals are connected with the CD (Carrier | 
|  | Detect) pin of the serial line they use to communicate with the | 
|  | host. In this case use the SERIAL_LINE client support. | 
|  |  | 
|  | Some antennae's PPS signals are connected with some special host | 
|  | inputs so you have to enable the corresponding client support. | 
|  |  | 
|  | To compile this driver as a module, choose M here: the module | 
|  | will be called pps_core.ko. | 
|  | if PPS | 
|  |  | 
|  | config PPS_DEBUG | 
|  | bool "PPS debugging messages" | 
|  | help | 
|  | Say Y here if you want the PPS support to produce a bunch of debug | 
|  | messages to the system log.  Select this if you are having a | 
|  | problem with PPS support and want to see more of what is going on. | 
|  |  | 
|  | config NTP_PPS | 
|  | bool "PPS kernel consumer support" | 
|  | depends on !NO_HZ_COMMON | 
|  | help | 
|  | This option adds support for direct in-kernel time | 
|  | synchronization using an external PPS signal. | 
|  |  | 
|  | It doesn't work on tickless systems at the moment. | 
|  |  | 
|  | endif | 
|  |  | 
|  | source drivers/pps/clients/Kconfig | 
|  |  | 
|  | source drivers/pps/generators/Kconfig | 
|  |  | 
|  | endmenu |