Hi,

I'm developing a PCIe Device, therefore I need some test programs and a
driver. I have to transfer data from the Device to Memory of my host
processor by DMA. This shall be happen via DMA.


Testing shall be done under Linux (Centos 4.7 kernel 2.6.9). Actually I have
a driver and a program but recieve a segmentation fault. Someone helped to
setup the driver, but he hasn't time for it.


What I'm doing in the driver

static void* pvFPGA_PCI_ReadBuffer = NULL;


pvFPGA_PCI_ReadBuffer = (void*)__get_free_pages(GFP_KERNEL | GFP_DMA,
get_order(ulFPGA_PCI_Read_SIZE));

physical = virt_to_bus((void *)pvFPGA_PCI_ReadBuffer);

if( io_remap_page_range
(vma,
vma->vm_start,
physical,
vma->vm_end - vma->vm_start,
vma->vm_page_prot)) return -EAGAIN;
vma->vm_ops = &abaxmem_remap_vm_ops;
abaxmem_vma_open(vma);

Just now the buffer is be mapped to the dev (/dev/abaxrd).
Can I read the device in a "cat" manner?


In my program I do:


fh_read = fopen ("/dev/abaxrd", "r+");

pci_read_mem = (unsigned long*) mmap (
NULL,
0x1000, /* wieviele Bytes ? */
PROT_READ | PROT_WRITE, /* lesen und schreiben */
MAP_SHARED, /* keine Kopie */
fileno(fh_read), /* Handle zum /dev */
(__off_t)offset); /* Basisadresse */



The segmentation fault happens, if I try to read from the buffer

printf ("Counter(in pci_read_mem[0..3]): %ld %ld %ld %ld\n",
pci_read_mem[0],pci_read_mem[1],pci_read_mem[2],pci_read_mem[3]);


I check, whether the mappings and all other things are successfully, they
are.

What is wrong.

If you need the whole source, please ask me.

On Wed, 30 Sep 2009 10:28:12 +0200, Thomas Reinemann
tom.foren at (no spam) abaxor.de> wrote:

Hi,

I'm developing a PCIe Device, therefore I need some test programs and a
driver. I have to transfer data from the Device to Memory of my host
processor by DMA. This shall be happen via DMA.


Testing shall be done under Linux (Centos 4.7 kernel 2.6.9). Actually I
have a driver and a program but recieve a segmentation fault. Someone
helped to setup the driver, but he hasn't time for it.


What I'm doing in the driver

static void* pvFPGA_PCI_ReadBuffer = NULL;


pvFPGA_PCI_ReadBuffer = (void*)__get_free_pages(GFP_KERNEL | GFP_DMA,
get_order(ulFPGA_PCI_Read_SIZE));

physical = virt_to_bus((void *)pvFPGA_PCI_ReadBuffer);

if( io_remap_page_range
(vma,
vma->vm_start,
physical,
vma->vm_end - vma->vm_start,
vma->vm_page_prot)) return -EAGAIN;
vma->vm_ops = &abaxmem_remap_vm_ops;
abaxmem_vma_open(vma);

Just now the buffer is be mapped to the dev (/dev/abaxrd).
Can I read the device in a "cat" manner?


In my program I do:


fh_read = fopen ("/dev/abaxrd", "r+");

pci_read_mem = (unsigned long*) mmap (
NULL,
0x1000, /* wieviele Bytes ? */
PROT_READ | PROT_WRITE, /* lesen und schreiben */
MAP_SHARED, /* keine Kopie */
fileno(fh_read), /* Handle zum /dev */
(__off_t)offset); /* Basisadresse */



The segmentation fault happens, if I try to read from the buffer

printf ("Counter(in pci_read_mem[0..3]): %ld %ld %ld %ld\n",
pci_read_mem[0],pci_read_mem[1],pci_read_mem[2],pci_read_mem[3]);


I check, whether the mappings and all other things are successfully, they
are.

What is wrong.

If you need the whole source, please ask me.

Do you want to do DMA or memory-mapped I/O? You seem to be doing a
little of both. That probably won't work. Or I misunderstand...

A link to the code might help.

Bill Waddington wrote:

On Wed, 30 Sep 2009 10:28:12 +0200, Thomas Reinemann
tom.foren at (no spam) abaxor.de> wrote:

Hi,

I'm developing a PCIe Device, therefore I need some test programs and a
driver. I have to transfer data from the Device to Memory of my host
processor by DMA. This shall be happen via DMA.

If you need the whole source, please ask me.

Do you want to do DMA or memory-mapped I/O? You seem to be doing a
little of both. That probably won't work. Or I misunderstand...

You may right. What is the difference?. I'm an FPGA Designer, not a driver
programmer. The PCIDevice makes memory write requests. Therefore I would
say DMA is needed.


A link to the code might help.

http://www.abaxor.de/download/abaxmem.tar.gz

On Thu, 01 Oct 2009 09:08:48 +0200, Thomas Reinemann
tom.foren at (no spam) abaxor.de> wrote:

Bill Waddington wrote:

On Wed, 30 Sep 2009 10:28:12 +0200, Thomas Reinemann
tom.foren at (no spam) abaxor.de> wrote:

Hi,

I'm developing a PCIe Device, therefore I need some test programs and a
driver. I have to transfer data from the Device to Memory of my host
processor by DMA. This shall be happen via DMA.

[snippage]


If you need the whole source, please ask me.

Do you want to do DMA or memory-mapped I/O? You seem to be doing a
little of both. That probably won't work. Or I misunderstand...

You may right. What is the difference?. I'm an FPGA Designer, not a driver
programmer. The PCIDevice makes memory write requests. Therefore I would
say DMA is needed.


A link to the code might help.

http://www.abaxor.de/download/abaxmem.tar.gz


I'll try for a more detailed answer later. And have a look at your
code. In the meantime, are you using "Linux Device Drivers 3rd
Edition" as a reference? If not, you should be.
Do you mean lwn.net/Kernel/LDD3/, yes I read it the Chapter 15. But the guy,

I'm an old FPGA and board designer forced to wing it as a driver
writer.
I started with the first Xilinx devices in the early 1990s.

There are lots of
examples in the kernel source tree too.
Yes, but I'm looking for a test utility. The driver will be only used

Ultimately, do you want the DMA data to land in kernel memory, or
a user buffer?
It seems I've problems to access the kernel memory, mapped to a device. A