Date: Mon, 23 May 2016 20:18:26 -0700 From: John Baldwin <jhb@freebsd.org> To: Adrian Chadd <adrian@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r300548 - in head/sys: conf dev/bhnd dev/bhnd/bhndb dev/bhnd/cores/chipc dev/bhnd/nvram dev/bhnd/siba modules/bhnd modules/bhnd/cores/bhnd_chipc Message-ID: <2018441.udrSCt4JcK@ralph.baldwin.cx> In-Reply-To: <201605240112.u4O1CJOt063645@repo.freebsd.org> References: <201605240112.u4O1CJOt063645@repo.freebsd.org>
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On Tuesday, May 24, 2016 01:12:19 AM Adrian Chadd wrote: > Author: adrian > Date: Tue May 24 01:12:19 2016 > New Revision: 300548 > URL: https://svnweb.freebsd.org/changeset/base/300548 > > Log: > [bhnd] Implement pass-through resource management for ChipCommon. > > This patchset adds support to bhnd_chipc for sharing SYS_RES_MEMORY > resources with its children, allowing us to hang devices off of > bhnd_chipc that rely on access to a subset of the device register space > that bhnd_chipc itself must also allocate. > > We could avoid most of this heavy lifting if RF_SHAREABLE+SYS_RES_MEMORY > wasn't limited to use with allocations at the same size/offset. > > As a work-around, I implemented something similar to vga_pci.c, which > implements similar reference counting of of PCI BAR resources for its > children. > > With these changes, chipc will use reference counting of SYS_RES_MEMORY > allocation/activation requests, to decide when to allocate/activate/ > deactivate/release resources from the parent bhnd(4) bus. > > The requesting child device is allocated a new resource from chipc's > rman, pointing to (possibly a subregion of) the refcounted bhnd resources > allocated by chipc. > > Other resource types are just passed directly to the parent bhnd bus; > RF_SHAREABLE works just fine with IRQs. > > I also lifted the SPROM device code out into a common driver, since this > now allows me to hang simple subclasses off of a common driver off of both > bhndb_pci and bhnd_chipc. Hmm, what the PCI-PCI bridge driver does with NEW_PCIB is to allocate a single resource from its parent bus for each I/O window it decodes. It then creates a rman that is populated with the addresses in that resource and suballocates from that rman. This allows child devices to allocate non-overlapping resources exclusively (they could also do shareable mappings for subsets if applicable). Right now NEW_PCIB assumes it can pass one of these "child" resources up to the nexus to have it "mapped" via bus_activate_resource(). However, the recently added bus_map_resource() provides a cleaner way to do this where a bridge device can request a mapping for the sub-range of the resource on its "upstream" side that corresponds to the range used by a resource for a child device. -- John Baldwin
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