drm_device from another device driver? (was: Re: block device backed by DRM buffer object)

[Steven Newbury]

I've been reading up on the device model and studying kernel sources for the last couple of days, but I can't figure out how to get a pointer to the radeon_device struct for a specific card, or the parent drm_device from an external device driver.

I imagine I somehow need to take a reference to the drm class kobject for the card in question, and in so doing presumably I should then be able to discover the pointer to device.

Can someone point me to an example or provide a snippet to demonstrate?

Alternatively, if I'm wandering down the wrong path, a sign to lead my way would be appreciated!