Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH RFC 1/8] Introduce dynamic clock devices | Date | Mon, 6 Dec 2010 15:14:49 +0100 |
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On Saturday 04 December 2010, Richard Cochran wrote: > On Mon, Nov 08, 2010 at 07:38:41AM +0100, Arnd Bergmann wrote: > > On Thursday 04 November 2010, Richard Cochran wrote: > > > +struct clock_device { > > > + struct file_operations fops; > > > + struct file_operations *driver_fops; > > > + struct clock_device_operations *ops; > > > + struct cdev cdev; > > > + struct kref kref; > > > + struct mutex mux; > > > + void *priv; > > > + int index; > > > + bool zombie; > > > +}; > > > > You should really not need the file_operations here, neither the > > struct nor the pointer. Just define a static file_operations > > structure containing clock_device_open and clock_device_release, > > and whatever else you might need, then add the driver's operations > > to clock_device_operations, and pass the clock_device pointer > > directly to them, instead of passing the file/inode pointers. > > Arnd, I'm working a revision of this series, and I am not sure I > understand your comment. > > The intent here was to allow clock drivers to register a character > device through the clock_device API, since some clocks (hpet, rtc) > already offer a chardev interface. > > The same FD from the open character device will also be usable as a > clockid for the generic posix clock_get/settime calls. Thus, the > clock_device layer needs to hook into the file open/release functions.
Ok, it wasn't clear that you use this to hook the existing file operations, I now understand why you did it this way, but I think my point is still valid.
> Are you suggesting that I simply offer all of the functions from a > 'struct file_operations' (sans file/inode) in the 'struct > clock_device_operations' too?
Yes, exactly.
> I wanted to avoid duplicating the file_operations functions, so that > future changes in those functions would automatically trickle down to > the clock drivers.
No need, these rarely change. More importantly, if you want to offer a consistent interface across all these, I would make the interface as restrictive as possible rather than offering all of the file operations. Have a look which operations are actually used by the character devices you want to support, and then pass through the superset of those, but not more.
Arnd
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