Messages in this thread | | | From | Sven Van Asbroeck <> | Date | Tue, 21 May 2019 12:53:45 -0400 | Subject | Re: [PATCH] staging: fieldbus: anybuss: force address space conversion |
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On Tue, May 21, 2019 at 12:24 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > what is so odd about this code that makes you have to jump through > strange hoops that no other driver has to? >
Basically because it creates a regmap which accesses __iomem memory, instead of i2c/spi.
This was done because future hardware in the company's pipeline will access device register space through spi, instead of through a parallel memory bus.
The lower driver just has to create the appropriate regmap, __iomem or spi, and pass it to the upper driver, which does not have to know about the exact way the h/w gets accessed. So regmap is used as a hw abstraction layer.
The issue here is that a regmap context is a 'void *' yet the parallel memory base pointer is 'void __iomem *'. And so the two are incompatible.
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