On Mon, Feb 22, 2016 at 08:48:39PM +0900, Akinobu Mita wrote:

This adds userspace consumer for common clock.

This driver is inspired from Userspace regulator consumer
(REGULATOR_USERSPACE_CONSUMER) and it is useful for test purposes and
some classes of devices that are controlled entirely from user space.

Whether the kernel handles a clock or userspace does should have nothing 
to do with DT. Plus DT does not expose many of the clocks, so any 
debug feature needs to expose all clocks and be independent of DT.

Beyond debug, I don't think we should be exposing clock control to 
userspace.

Example binding and usages:

clksqw_userspace_consumer {
	compatible = "linux,clock-userspace-consumer";
	clocks = <&clksqw>;
};

	# cd /sys/devices/platform/clksqw_userspace_consumer
	# echo 8192 > rate
	# echo 1 > enable

This also create new COMMON_CLK_DEBUG option and this userspace clock
consumer depends on it.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <redacted>
---
* v2
- change compatible property to "linux,clock-userspace-consumer"
- rename sysfs file from 'state' to 'enable'

While it is good this is under a debug option, it also needs to be under 
debugfs, not sysfs.

- create new COMMON_CLK_DEBUG option

 .../bindings/clock/clk-userspace-consumer.txt      |  17 +++
 drivers/clk/Kconfig                                |   9 ++
 drivers/clk/Kconfig.debug                          |   9 ++
 drivers/clk/Makefile                               |   1 +
 drivers/clk/clk-userspace-consumer.c               | 169 +++++++++++++++++++++
 5 files changed, 205 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/clk-userspace-consumer.txt
 create mode 100644 drivers/clk/Kconfig.debug
 create mode 100644 drivers/clk/clk-userspace-consumer.c