Re: How to generate hotplug events in drivers?

[Greg KH <greg@kroah.com>]

On Fri, Aug 13, 2004 at 01:09:33PM -0400, Stephen Glow wrote:
> Thanks for the response, things seem to be working now.

Good.

> I'm still a little fuzzy about how all this works together, but the
> picture is starting to become a bit clearer.  Here are the basic steps I
> took in my PCI driver to get the device node to show up, please let me
> know if anyone sees an error here:
> 
> In the init module function, I create a new class_simple pointer:
> 
> static struct class_simple *myclass;
> 
> int init_module( void )
> {
> ~    ...
> ~    myclass = class_simple_create( THIS_MODULE, "myclassname" );
> ~    ...
> }
> 
> This causes the new class directory to show up under /sys/class
> 
> In the PCI probe function I do the following:
> 
> probe(...)
> {
> ~   ...
> 
> ~   // Allocate a device numer
> ~   dev_t mydev;
> ~   alloc_chrdev_region( &mydev, 0, 1, "mydevicename" );
> 
> ~   // Add this device number to my class.  Note I'm passing NULL for
> ~   // the device pointer.  I'm not exactly sure what this is for, but
> ~   // most devices in the kernel tree seem to pass NULL here.
> ~   class_simple_add_device( myclass, mydev, NULL, "mydevicename" );

Pass in a pointer to the struct pci_dev ->dev structure.  Something
like &pci_dev->dev should work well.  Then you will see the "device"
symlink show up in your class device directory in sysfs, which makes
tools like udev much easier to use.

> ~   // Finally, I init and add my cdev structure.
> ~   cdev_init( &mycdev, &myfops );
> ~   mycdev.owner = THIS_MODULE;

Not needed, as it should be pulled from the fops structure.

> ~   kobject_set_name( &mycdev.kobj, "mydevicename" );

Not needed anymore.

> ~   cdev_add( &mycdev, mydev, 1 );

You might want to move the class_simple_add_device() line after the
cdev_add line, just to handle the error conditions easier.

Other than those minor things, this looks good.

thanks,

greg k-h