On Thu, Feb 14, 2013 at 02:47:10PM -0800, Tony Lindgren wrote: > * Paul Walmsley <paul@xxxxxxxxx> [130214 13:44]: > > Hi, > > > > On Thu, 14 Feb 2013, Paul Walmsley wrote: > > > > > So instead of something bus-specific like that, a better way would be to > > > use something like: > > > > > > va = dev->bus->ioremap( ... ); > > > va = dev->bus->iounmap( ... ); > > > > Something like this is what I was thinking. Obviously there would be more > > patches needed, for the various arches, etc.; and I'm not convinced that > > the function pointer init is done at the right time yet. Comments welcome. > > > > > > - Paul > > > > > > From: Paul Walmsley <paul@xxxxxxxxx> > > Date: Thu, 14 Feb 2013 13:49:58 -0700 > > Subject: [PATCH] EXPERIMENTAL: device/ARM: allow buses to override ioremap*() > > and iounmap() > > > > On some hardware, such as OMAP, the bus abstraction code needs to call > > ioremap(), since some SoC-integration registers are located in the > > device address space. But generic device drivers should be able to > > call ioremap() from driver code, for the majority of situations where > > this isn't necessary. This experimental patch allows Linux bus abstraction > > code to override all of the ioremap*() and iounmap() functions. In the OMAP > > case, this would be used to return the previously-mapped address range from > > the bus code, when called for the device's register area. This would avoid > > a duplicate TLB mapping for that space. > > > > This might also be useful as a generic replacement for pci_ioremap_bar(). > > > > Compile-tested only. > > The other option could be to allow custom ioremap function pointers > based on address range in __arm_ioremap_pfn_caller() the same way as > the SoC specific static mappings are allowed. That would require adding > a function pointer to struct map_desc. > > Maybe that would do the trick? I'm not sure we should even try that. I mean, eventually (maybe in 100 years) we wouldn't mach-* at all and even struct map_desc would be dynamically initialized by data passed in via DTB, right ? Just consider Arnd's patch for the "machine_desc-less" DT boot. If we add a function pointer to struct map_desc, it will just become yet another function pointer to be removed later. -- balbi
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