QoS: Enhance framework to support cpu/irq specific QoS requests

QoS request for CPU_DMA_LATENCY can be better optimized if the request
can be set only for the required cpus and not all cpus. This helps save
power on other cores, while still gauranteeing the quality of service.

Enhance the QoS constraints data structures to support target value for
each core. Requests specify if the QoS is applicable to all cores
(default) or to a selective subset of the cores or to a core(s), that the
IRQ is affine to.

QoS requests that need to track an IRQ can be set to apply only on the
cpus to which the IRQ's smp_affinity attribute is set to. The QoS
framework will automatically track IRQ migration between the cores. The
QoS is updated to be applied only to the core(s) that the IRQ has been
migrated to.

Idle and interested drivers can request a PM QoS value for a constraint
across all cpus, or a specific cpu or a set of cpus. Separate APIs have
been added to request for individual cpu or a cpumask.  The default
behaviour of PM QoS is maintained i.e, requests that do not specify a
type of the request will continue to be effected on all cores.  Requests
that want to specify an affinity of cpu(s) or an irq, can modify the PM
QoS request data structures by specifying the type of the request and
either the mask of the cpus or the IRQ number depending on the type.
Updating the request does not reset the type of the request.

The userspace sysfs interface does not support CPU/IRQ affinity.

Change-Id: I09ae85a1e8585d44440e86d63504ad734e8e3e36
Signed-off-by: Praveen Chidambaram <pchidamb@codeaurora.org>

Conflicts:
	kernel/power/qos.c

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index 129f7c0e1483..73bfa1624004 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -43,6 +43,17 @@ registered notifiers are called only if the target value is now different.
 Clients of pm_qos need to save the returned handle for future use in other
 pm_qos API functions.
 
+The handle is a pm_qos_request object. By default the request object sets the
+request type to PM_QOS_REQ_ALL_CORES, in which case, the PM QoS request
+applies to all cores. However, the driver can also specify a request type to
+be either of
+        PM_QOS_REQ_ALL_CORES,
+        PM_QOS_REQ_AFFINE_CORES,
+        PM_QOS_REQ_AFFINE_IRQ,
+
+Specify the cpumask when type is set to PM_QOS_REQ_AFFINE_CORES and specify
+the IRQ number with PM_QOS_REQ_AFFINE_IRQ.
+
 void pm_qos_update_request(handle, new_target_value):
 Will update the list element pointed to by the handle with the new target value
 and recompute the new aggregated target, calling the notification tree if the
@@ -56,6 +67,13 @@ the request.
 int pm_qos_request(param_class):
 Returns the aggregated value for a given PM QoS class.
 
+int pm_qos_request_for_cpu(param_class, cpu):
+Returns the aggregated value for a given PM QoS class for the specified cpu.
+
+int pm_qos_request_for_cpumask(param_class, cpumask):
+Returns the aggregated value for a given PM QoS class for the specified
+cpumask.
+
 int pm_qos_request_active(handle):
 Returns if the request is still active, i.e. it has not been removed from a
 PM QoS class constraints list.