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Old 07-17-2008, 12:27 PM   #1
niteshg
LQ Newbie
 
Registered: Nov 2004
Location: NJ
Posts: 29

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ioread32 returns 0xffffffff; pci driver


I am writing a driver for a pci card. The pci card has got a powerspan II on it as a pci bridge.
The configuration space contains 4096 bytes:
The driver was working properly with ioread32 before. but now it gives me a problem.
I am copying the following lines relevant to the configuration of pci



np = kmalloc(sizeof(struct my_dev), GFP_KERNEL);
if (!np) {
result = -ENOMEM;
printk(KERN_ALERT "mydev registered1");
}

printk(KERN_ALERT "mydev registered");

memset(np, 0,sizeof(struct my_dev));

init_MUTEX(&np->sem);

if (!pci_enable_device(pdev))
printk(" device enabled \n");
if(request_mem_region(pci_resource_start(pdev,1),4096,"pci_skel"));
printk("device given memory\n");

pci_set_drvdata(pdev, np);

np->base_addr=ioremap(pci_resource_start(pdev,1),4096);

iowrite32( 0x00000000,np->base_addr+0x004);
t= ioread32(np->base_addr + 0x004);
printk(KERN_DEBUG " yhu %x: %x",np->base_addr, t);



When I write 0 to 0x004 and read it back it returns 0xffffffff

Could comeone help me otu here please.
I am using fedora core 2 , kernel 2.6.13

Thanks,
N
 
Old 07-18-2008, 05:55 AM   #2
pinniped
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Registered: May 2008
Location: planet earth
Distribution: Debian
Posts: 1,732

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What do you mean the driver was working before but not now? How did you test it? What changed?

Since you're getting all those Fs, it looks like you're not writing to writable memory (a 'read-only' register or else you have no access to the region).

Did you check the value you got from ioremap() to see if it's valid?

Last edited by pinniped; 07-18-2008 at 05:57 AM.
 
Old 07-18-2008, 06:42 AM   #3
niteshg
LQ Newbie
 
Registered: Nov 2004
Location: NJ
Posts: 29

Original Poster
Rep: Reputation: 15
Quote:
Originally Posted by pinniped View Post
What do you mean the driver was working before but not now? How did you test it? What changed?

Since you're getting all those Fs, it looks like you're not writing to writable memory (a 'read-only' register or else you have no access to the region).

Did you check the value you got from ioremap() to see if it's valid?
The driver just had a few lines where I was enabling the interrupt mask bits in the configuration register and then waiting for a interrupt. I had a interrupt service subroutine in the driver.
The configuration registers were writable since I was able to read the registers and the change them.
The initializztion of the powerspanII was done by the powerpc in the FPGA(The pci card is a FPGA card).

Now I have disabled the powerpc inside the fpga and am trying to initialize the powerspan II from the probe function of the driver.
I dont have interrupt so I have disabled the service routine.

I was getting a ioremap output of something like 0xebeef000. How can I confirm if its valid or not?
Thanks,
N
 
Old 12-02-2009, 04:48 AM   #4
orback
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Registered: Oct 2009
Posts: 7

Rep: Reputation: 0
I know that this thread was posted longago but I have exactly the same problem when trying to read from a FPGA board, the return value from ioread32 is always 0xffffffff. I am very interesed in how you solved the problem.

Thanks
 
  


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