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From: Sven Van Asbroeck <>
To: Greg KH <>
	Linux Kernel Mailing List <>,
	Dan Carpenter <>
Subject: Re: [PATCH] staging: fieldbus: anybuss: force address space conversion
Date: Tue, 21 May 2019 12:53:45 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, May 21, 2019 at 12:24 PM Greg KH <> 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.

  reply	other threads:[~2019-05-21 16:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-21 14:51 Sven Van Asbroeck
2019-05-21 15:10 ` Dan Carpenter
2019-05-21 15:19   ` Sven Van Asbroeck
2019-05-21 15:42     ` Greg KH
2019-05-21 15:53       ` Sven Van Asbroeck
2019-05-21 16:24         ` Greg KH
2019-05-21 16:53           ` Sven Van Asbroeck [this message]
2019-05-21 17:06             ` Sven Van Asbroeck

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