bus_alloc_resource question

From: Chuck Tuffli (chuck_tuffli_at_agilent.com)
Date: 07/27/04

  • Next message: M. Warner Losh: "Re: bus_alloc_resource question" 
    Date: Mon, 26 Jul 2004 18:59:24 -0700
To: hackers@freebsd.org

    I'm having some trouble adding a bus resource and am hoping someone
    can point out where I goofed.

    The host bus to a new x86 chipset has a memory mapped region in PCI
    space that provides access to status and control registers. For a
    driver to get access to this region, I figured it should call
    bus_alloc_resource() the same as for any other memory mapped region.
    This currently doesn't "just work" as the region is not a part of any
    device's BARs. To add this region as a resource, I used
    bus_set_resource()

        device_t dev;
        uint32_t e_mem = 0xe0000000;
        struct resource *ecfg_res;

        dev = pci_find_device(PCI_VENDOR_INTEL, ...);
        bus_set_resource(dev, SYS_RES_MEMORY, e_mem, 0xe0000000, 0x10000000);

    but a subsequent call to bus_alloc_resource() returns NULL

        ecfg_res = bus_alloc_resource(dev, SYS_RES_MEMORY, &e_mem,
                0, ~0, 1, RF_ACTIVE | RF_SHAREABLE);

    A call to bus_get_resource() shows that the resource did get set as
    the call returns the correct starting address and count. Is there
    something else that needs to happen between the set and the alloc? Is
    this even the correct approach? Thanks in advance! 

    -- 
Chuck Tuffli
Agilent Technologies, Storage Area Networking
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  • Next message: M. Warner Losh: "Re: bus_alloc_resource question"

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