Re: [PATCH RFC 1/8] Introduce dynamic clock devices

On Mon, Nov 08, 2010 at 07:38:41AM +0100, Arnd Bergmann wrote:

On Thursday 04 November 2010, Richard Cochran wrote:

quoted

+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.

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?

I wanted to avoid duplicating the file_operations functions, so that
future changes in those functions would automatically trickle down to
the clock drivers.

Thanks,
Richard