From mboxrd@z Thu Jan  1 00:00:00 1970
From: greg@kroah.com (Greg KH)
Date: Wed, 4 May 2011 07:55:13 -0700
Subject: Faking PCI devices?
In-Reply-To: <BANLkTikFCqqNO9G-6w2Yck0CEbNQ0eF-YQ@mail.gmail.com>
References: <BANLkTikFCqqNO9G-6w2Yck0CEbNQ0eF-YQ@mail.gmail.com>
Message-ID: <20110504145513.GA12265@kroah.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Wed, May 04, 2011 at 11:39:20AM +0200, Manohar Vanga wrote:
> Hi,
> 
> I have written a simulated driver for a PCI board and am looking for a clean
> way to use the driver. Currently, I am setting the PCI ids to PCI_ANY_ID and
> only allowing a single probe call to go through using a global variable
> (concurrency issues but I don't care for the simulation).
> 
> static int n
> ...
> static int fake_board_probe(struct pci_dev *pdev, const struct pci_device_id
> *ent)
> {
> ??? if (n == 1)
> ??????? return -1;

Please return a proper error value, like -ENODEV.

> ??? n = 1;
> ??? ...
> }
> static int fake_board_init(void)
> {
> ??? n = 0;
> ??? ....
> }
> 
> I want to do a cleaner job of this and wanted to write a PCI bridge driver that
> actually registers the devices with the correct IDs that I need. This also
> gives me the advantage of being able to register multiple devices which is a
> useful for the simulation I am working on.
> Can anyone point me in the right direction for this? Most of the code (eg.
> struct pci_controller) seem to be architecture specific.

Just register your device, and then don't use any global variables to
the driver.  Put them all in your struct pci_dev private area and you
will be fine.

There's thousands of examples of this in the kernel.

hope this helps,

greg k-h