Date: Tue, 23 Sep 2008 10:36:59 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-acpi@freebsd.org Cc: Gavin Atkinson <gavin@freebsd.org> Subject: Re: Writing a driver: how do I get resources? Message-ID: <200809231037.00392.jhb@freebsd.org> In-Reply-To: <1222173505.80882.15.camel@buffy.york.ac.uk> References: <1222173505.80882.15.camel@buffy.york.ac.uk>
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On Tuesday 23 September 2008 08:38:25 am Gavin Atkinson wrote: > Hi all, > > Please forgive me if this email makes very little sense: I've never > really looked at how ACPI works from a driver's perspective, so don't > really know if what I'm trying to do is even correct. > > I'm expanding the acpi_sony driver to cover the PNP ID SNY6001. When I > simply claim it by returning 0 from the probe, I get the following I/O range: > > acpi_sony0: <Sony programmable I/O> port 0-0x1f on acpi0 > > However, if I'm reading the AML[1] and Linux drivers[2] correctly, this > is not the correct range. It appears that the _PRS method offers a > choice of four I/O ranges and four IRQs, one of which is then selected > by evaluating _SRS. None of them are 0-0x1f. > > Firstly, does that make sense? Secondly, how do I do this from a > driver? I can't see any other drivers that seem to get this involved in > ACPI, indeed the only mention of evaluating _PRS is within the ACPI code > itself. > > Lastly, I only have intermittent access to this laptop, so I apologise > if I can't test things quickly. Our ACPI driver isn't smart enough yet (AFAIK) to allocate new resources for a device that doesn't have any. That logic should be in acpi_alloc_resource() and once that is present then your driver just needs to do the usual bus_alloc_resource() stuff to work. -- John Baldwin
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