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LMK04832: Linux driver support

Liam Beguin
Prodigy 71 points

Part Number: LMK04832

Hi,

We are using the LMK04832 clock generator as a replacement for another chip and I was wondering what kind of support is available on Linux.

I looked in the ti-linux tree but I couldn't find a driver that seems to be compatible.

Thanks, 

Liam

  • 0
    TI__Mastermind 28590 points

    Hello Liam,

    I'm afraid we do not have a linux driver.  What are you looking to achieve?

    73,
    Timothy

  • 0 in reply to Timothy T
    Prodigy 71 points

    Hi Timothy,

    At first I'd like to have a driver to setup the chip at boot time with configurations loaded from the devicetree.

    Then maybe add a sysfs interface for runtime configuration.

    Liam

  • 0 in reply to Liam Beguin
    TI__Mastermind 28590 points

    Hello Liam,

    You can use the TICS Pro software to generate a register map that you can program for boot time.

    When you say configurations loaded from the device tree, can you elaborate what you mean by that?  You could save multiple register maps and program them in their entirety, or just the differences.  The only register to take care when programming is the PLL2 N register.  When it is programmed the VCO calibration will start.  So that should generally be the last register programmed if case a change to VCO frequency is required.

    At run time, what do you anticipate changing?  Loop filter parameters?  Outputs off or on - or different clock format?  Input or output frequencies?

    As for input/output frequencies.  The LMK04832 has integer output dividers.  This does limit the output frequencies you can change. If you were to change a output frequency, the new output frequency would need to be an integer division of the current VCO frequency.  If the new frequency is not an integer relationship to the current VCO frequency, a new VCO frequency must be calculated.  If the requested output frequencies are "poorly related" it is possible for the calculated VCO frequency may not be supported by the VCO range of the LMK04832.  --> Do you anticipate the case of poorly related frequencies occurring, or would the requested frequencies be requested with the knowledge of the supported frequencies?

    Thank-you for helping me understand your need.

    73,
    Timothy

  • 0 in reply to Timothy T
    Prodigy 71 points

    Hi Timothy,

    Thanks for your detailed reply. After more consideration, we won't need to do the runtime configuration.

    So my plan would be to write a driver to load the register map (from TICS Pro) at boot time. 

    Liam