Re: How does the driver initialize corresponding with several same devices ?
On Wed, Apr 18, 2012 at 04:32:12PM +0530, anish singh wrote:
On Wed, Apr 18, 2012 at 4:18 PM, Philipp Ittershagen <p.ittershagen@googlemail.com> wrote:
On Wed, Apr 18, 2012 at 05:16:01PM +0800, Li Haifeng wrote:
I make a driver module and built in the kernel. There are three devices use the same driver on the hardware platform. To use each device, the probe function of the driver module should be probed. So, the driver module is registered in the kernel.
My question is, how times should the probe function of the driver be called and create nodes in devfs to corresponding with the three devices?
It depends on what your architecture supports. If you have support for device tree, your entry in the device tree will make the subsystem call your probe function for each device it finds. You can then check the `compatible` entry of the device node and your driver is then able to register itself to the kernel subsystem. Without device tree what would be your answer as i guess device tree has come recently in picture but not sure.
Let me rephrase your question and see if I understand it correctly. You have a probe function which already gets called for each device in your platform and you want to know how to make each device accessible in userspace (using i.e. devfs nodes) ? Greetings, Philipp
On Wed, Apr 18, 2012 at 4:37 PM, Philipp Ittershagen <p.ittershagen@googlemail.com> wrote:
On Wed, Apr 18, 2012 at 04:32:12PM +0530, anish singh wrote:
On Wed, Apr 18, 2012 at 4:18 PM, Philipp Ittershagen <p.ittershagen@googlemail.com> wrote:
On Wed, Apr 18, 2012 at 05:16:01PM +0800, Li Haifeng wrote:
I make a driver module and built in the kernel. There are three devices use the same driver on the hardware platform. To use each device, the probe function of the driver module should be probed. So, the driver module is registered in the kernel.
My question is, how times should the probe function of the driver be called and create nodes in devfs to corresponding with the three devices?
It depends on what your architecture supports. If you have support for device tree, your entry in the device tree will make the subsystem call your probe function for each device it finds. You can then check the `compatible` entry of the device node and your driver is then able to register itself to the kernel subsystem. Without device tree what would be your answer as i guess device tree has come recently in picture but not sure.
Let me rephrase your question and see if I understand it correctly. You have a probe function which already gets called for each device in your platform and you want to know how to make each device accessible in userspace (using i.e. devfs nodes) ? I think he wants to know how will he differentiate different devices as probe of the driver will be called three times for all the devices.Right?
Greetings,
Philipp
Thanks all of you. I got it. To platform driver, when it is registered by platform_driver_register, system will walk though the platform bus and match each device with driver. If there are several same device, all of these device will be probed. On Wed, Apr 18, 2012 at 7:11 PM, anish singh <anish198519851985@gmail.com> wrote:
On Wed, Apr 18, 2012 at 4:37 PM, Philipp Ittershagen <p.ittershagen@googlemail.com> wrote:
On Wed, Apr 18, 2012 at 04:32:12PM +0530, anish singh wrote:
On Wed, Apr 18, 2012 at 4:18 PM, Philipp Ittershagen <p.ittershagen@googlemail.com> wrote:
On Wed, Apr 18, 2012 at 05:16:01PM +0800, Li Haifeng wrote:
I make a driver module and built in the kernel. There are three devices use the same driver on the hardware platform. To use each device, the probe function of the driver module should be probed. So, the driver module is registered in the kernel.
My question is, how times should the probe function of the driver be called and create nodes in devfs to corresponding with the three devices?
It depends on what your architecture supports. If you have support for device tree, your entry in the device tree will make the subsystem call your probe function for each device it finds. You can then check the `compatible` entry of the device node and your driver is then able to register itself to the kernel subsystem. Without device tree what would be your answer as i guess device tree has come recently in picture but not sure.
Let me rephrase your question and see if I understand it correctly. You have a probe function which already gets called for each device in your platform and you want to know how to make each device accessible in userspace (using i.e. devfs nodes) ? I think he wants to know how will he differentiate different devices as probe of the driver will be called three times for all the devices.Right?
Greetings,
Philipp
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
participants (3)
-
anish singh -
Li Haifeng -
Philipp Ittershagen