As multiplatform build is being adopted by more and more ARM platforms, initcall
function should be used very carefully. For example, when both arm_big_little_dt
and cpufreq-cpu0 drivers are compiled in, arm_big_little_dt driver may try to
register even if we had platform device for cpufreq-cpu0 registered.

To eliminate this undesired the effect, the patch changes arm_big_little_dt
driver to have it instantiated as a platform_driver. Then it will only run on
platforms that create the platform_device "arm-bL-cpufreq-dt".
Reported-and-tested-by: NRob Herring <robherring2@gmail.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If arm_big_little_dt driver is enabled, then it will always try to register with
big LITTLE cpufreq core driver. In case DT doesn't have relevant data for cpu
nodes, i.e. operating points aren't present, then we should exit early and
shouldn't register with big LITTLE cpufreq core driver. Otherwise we will fail
continuously from the driver->init() routine.

This patch fixes this issue.
Reported-and-tested-by: NJon Medhurst <tixy@linaro.org>
Reviewed-by: NJon Medhurst <tixy@linaro.org>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If "/cpus" node isn't present or "clock-latency" isn't defined we are
returning error currently. Let's return CPUFREQ_ETERNAL instead, so
that we don't fail.

Flag appropriate messages to user in such cases.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

By mistake we are returning zero for successful call to
dt_get_transition_latency(), whereas we should return
transition_latency.  Fix that.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

DT nodes should be put using of_node_put() to balance their usage counts. This
is not done properly in ARM's big LITTLE driver. Fix it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

big LITTLE is ARM's new Architecture focussing power/performance needs of modern
world. More information about big LITTLE can be found here:

http://www.arm.com/products/processors/technologies/biglittleprocessing.php
http://lwn.net/Articles/481055/

In order to keep cpufreq support for all big LITTLE platforms simple/generic,
this patch tries to add a generic cpufreq driver layer for all big LITTLE
platforms.

The driver is divided into two parts:
- Core driver: Generic and shared across all big LITTLE SoC's
- Glue drivers: Per platform drivers providing ops to the core driver

This patch adds in a generic glue driver which would extract information from
Device Tree.

Future SoC's can either reuse the DT glue or write their own depending on the
need.
Signed-off-by: NSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>