From owner-freebsd-new-bus  Wed May 24 17:32:22 2000
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To: new-bus@freebsd.org
Subject: Identify routines
Date: Wed, 24 May 2000 18:31:09 -0600
From: Warner Losh <imp@village.org>
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OK.  I'm pushing the envelope on isa drivers.   I'm abusing the
identify routine to go out and find boards.  The following usually
works, but sometimes fails.  Is there a good way to activate the
resources (or at least check to make sure that the resources are not
used by someone else) in the identify routine?

static void
foo_identify(driver_t *driver, device_t parent)
    int                 i;
    u_long              ports[] = { 
        0x100, 0x110, 0x120, 0x130, 0x140, 0x150, 0x160, 0x170,
        0x180, 0x1a0, 0x1b0, 0x1c0, 0x300, 0x310
    };
    int         nports = sizeof(ports) / sizeof(ports[0]);
    int                 rid;
    int			ok;
    struct resource     *res;
    u_long              addr = 0;
    foo_softc	sc;

    if (!devclass_get_device(devclass_find(DRIVERNAME), 0)) {
	/*
	 * Find where config says this device is at
	 */
	for (i = 0; i < nports; i++) {
	    rid = 0;
	    res = bus_alloc_resource(parent, SYS_RES_IOPORT, &rid, ports[i], 
		ports[i], PORTS_PER_BOARD, RF_ACTIVE);
	    if (!res)
		continue;
	    addr = rman_get_start(res);
	    sc.bst = rman_get_bustag(res);
	    sc.bsh = rman_get_bushandle(res);
	    ok = foo_card_present(&sc);
	    bus_release_resource(parent, SYS_RES_IOPORT, rid, res);
	    if (!ok)
		continue;
	    child = BUS_ADD_CHILD(parent, 0, DRIVERNAME, 0);
	    if (child == NULL)
		panic("foo_identify");
	    bus_set_resource(child, SYS_RES_IOPORT, 0, addr, PORTS_PER_BOARD);
	}
    }
}


I've noticed that sometimes I've found that this works great.  Other
times I get strange panics after this function has been called and the 
alloc/release were done.  If I replace it with something whose heart
looks more like:
	sc.bst = I386_BUS_SPACE_IO;
	sc.bsh = ports[i];
	ok = foo_card_present(&sc);
	if (!ok)
	    continue
	child = BUS_ADD_CHILD(...)
	.../* same */

then I see no panics and everything is suddenly cool.

My questions are:
	Is this a cool thing to do?
	If not, how do I do what I'm trying to do?
I'd love for this hardware to be plug and play, but it was built in
the late 1980s and the design hasn't changed much in all that time
(I'm writing support for some legacy hardware, so changing it isn't an
option).

Comments?

Warner


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