request_/release_mem_region() question

Rafael do Nascimento Pereira rnp at 25ghz.net
Mon Oct 6 08:11:03 EDT 2014


I have writen a driver that implements a simple platform device. It
basically
reads I/O Mapped registers using
request_mem_region()/ioremap()/release_mem_region()
and export its contents to user space using sysfs. This driver is used for
debugging
purposes.

The problem takes place when I try to read these registers when the
corresponding driver, that uses these I/O mapped registers, is loaded. In
other
words, I cannot request the memory region, it return a "device busy" error.
If I disable the the request_/release_mem_region() it works.

One questions arises from it:
Is there a way to read these I/O mapped registers without bypassing the
request_/release_mem_region() functions ?

Linux Kernel version: 3.10.54 on ARMv7

Best regards,
Rafael.

-- 


"It is not that I am so smart, it is just that I stay with problems longer."
--Albert Einstein
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