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ioremap() and port of linux to MPC7400 based SBC (VME board)

Discussion in 'Embedded' started by him, Feb 7, 2005.

  1. him

    him Guest

    I have run into a problem I am having a hard time figuring out.

    I have an MPC7400 SBC (PCI bus based) that has a device X residing
    at the following locations in memory:

    0x1860 0000 - 0x186f ffff device control register space
    0xb000 0000 - 0xbfff ffff device memory space

    Now assume for a moment that NOTHING special needs to be done to
    access either space once the system has booted and bus enumerator
    have set things up.

    ioremap() of the first physical address returns a VALID virtual
    address ... that I can read and write to. It works as expected
    because there are signature values at various offsets in the control
    register space.
    The virtual address returned is EQUAL to the physical address

    ioremap() of the second physical address also returns what appears to
    be a VALID virtual address although WRITES go nowhere and READS return
    all ff's.
    The virtual address returned is 0xc100 0000

    Now my question ... I have the source for the port. Where should I focus
    my efforts in trying to figure this out?

    I have read the device drivers book and certain that I am following
    the rules.

    I should also mention that there is an IO controller seperate from the
    MPC7400 that I use to verify that the device X control and memory exist
    in THAT physical range.

    If Only I can access them through ioremap()

    him, Feb 7, 2005
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  2. No idea up to now, but what kernel, what linux? is it VM linux or uClinux?


    with best regards / mit freundlichen Grüßen

    Heinz-Jürgen Oertel
    | Heinz-Jürgen Oertel port GmbH http://www.port.de
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    | phone +49 345 77755-0 fax +49 345 77755-20
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    =?ISO-8859-15?Q?Heinz=2DJ=FCrgen?= Oertel, Feb 7, 2005
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  3. him

    sam Guest

    No idea up to now, but what kernel, what linux?
    Its a Timesys port of linux 2.4.20 to an MPC7400
    based system
    sam, Feb 7, 2005
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