linux-kernel - Re: character driver over PCI

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Message-id: <467EC986.7040300@shaw.ca>
Date:	Sun, 24 Jun 2007 13:44:06 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	ats <atita84@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: character driver over PCI

ats wrote:
>  have a  wireless network card over PCMCIA....i need to just access
> the registers of this card and pass this register details to the user
> application.Since i will not connect to the network at this stage i
> preferred bypassing the network stack.Hence instead of a network
> driver i went ahead writing a character driver.
> 
> 
> I inserted the PCI module using insmod..That called PCI
> probe....Inside PCI probe i registered by character driver by calling
> register_chrdev().And i remapped the card memory by calling the
> following sequence of functions.
> 
> 
> pci_resource_start
> request_mem_region
> ioremap
> 
> Then i created a device using mknod and called the open function of
> the character driver.....Till here everything works fine....
> 
> 
> Once the device opened i made a readl call to read the mapped
> memory..This fails..It gives me a segmentation fault.....If i call
> readl in the probe function it works fine and reads the memory at that
> location..However this call fails in open..What can be the reason...
> 
> Have i proceeded the right way....Are there any additional things to
> be set..Am working on linux 2.6 kernel
> 
> Attached below is my prog

I don't see where it is trying to read anything in this code. The way in 
which you're doing that is likely the problem..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@...pamshaw.ca
Home Page: http://www.roberthancock.com/

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