Reuse values of Qsys generics in C++ app

I think the only way to transmit those kind of parameters to the C/C++ app is through a custom component. Please note that this example is quite old, I'm still working on a design with Quartus 11 and SOPC builder, but I think it should still apply to QSys and HPS designs.

All those lines need to be put in the component's *_hw.tcl file

The component needs a custom elaboration callback

set_module_property ELABORATION_CALLBACK elaboration_proc

Create a generic parameter for the component that takes a clock frequency as value

add_parameter CLOCK_FREQ Integer
set_parameter_property CLOCK_FREQ SYSTEM_INFO { CLOCK_RATE clock }
set_parameter_property CLOCK_FREQ VISIBLE False
set_parameter_property CLOCK_FREQ AFFECTS_ELABORATION True
set_parameter_property CLOCK_FREQ AFFECTS_GENERATION False

For that property to work you need a clock input port with the "clock" name

# +-----------------------------------
#  | connection point clock
#  | 
add_interface clock clock end
set_interface_property clock clockRate 0
set_interface_property clock ENABLED true
add_interface_port clock csi_sys_Clk clk Input 1

And then in the elaboration procedure you can transmit the value to the software layer

# custom elaboration procedure
proc elaboration_proc { } {
  set_module_assignment embeddedsw.CMacro.CLOCK_FREQ 
}

It's probably overkill if you don't already have a custom component with custom driver but it's the only way I know, other than parsing the sopcinfo file yourself.