Hello Russell,
On Sat, 14 Jun 2008, Russell King - ARM Linux wrote:
> On Fri, Jun 06, 2008 at 06:30:53PM -0700, Tony Lindgren wrote:
> > omap_chip is set in mach-omap2/id.c by _set_omap_chip(). Other
> > code should use the omap_chip_is() function to test against omap_chip.
>
> > +/**
> > + * omap_chip_is - test whether currently running OMAP matches a chip type
> > + * @oc: omap_chip_t to test against
> > + *
> > + * Test whether the currently-running OMAP chip matches the supplied
> > + * chip type 'oc'. Returns 1 upon a match; 0 upon failure.
> > + */
> > +int omap_chip_is(struct omap_chip_id oci)
> > +{
> > + return (oci.oc & omap_chip.oc) ? 1 : 0;
> > +}
> > +EXPORT_SYMBOL(omap_chip_is);
>
> I've not seen any use cases for this function, so I don't know how it's
> intended to be used. However, is it really sensible for this to take a
> structure rather than just a value?
It was created as a structure so the size of the underlying bitmask can be
increased later without patching all of the structure definitions that use
it in other code. (Originally it was a typedef.) Here's a basic use
case:
struct foo {
...
struct omap_chip_id omap_chip;
};
static const struct foo foo_instance_omap2420 = {
...
.omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP2420)
};
static const struct foo foo_instance_omap3430 = {
...
.omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP3430)
};
static const struct foo *foo_instances[] = {
&foo_instance_omap2420,
&foo_instance_omap3430,
NULL
};
void fn(void) {
for (p = foo_instances; p; p++) {
if (omap_chip_is(p->omap_chip)
pr_debug("Chip type matches - use this structure");
}
- Paul
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