[RFC,3/3] QoS: Enhance framework to support cpu/irq specific QoS requests

diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index a5da5c7..32b864d 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -41,6 +41,17 @@  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
@@ -54,6 +65,13 @@  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.
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index e1b763d..05d7c46 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -9,6 +9,8 @@ 
 #include <linux/miscdevice.h>
 #include <linux/device.h>
 #include <linux/workqueue.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
 
 enum {
 	PM_QOS_RESERVED = 0,
@@ -40,7 +42,18 @@  enum pm_qos_flags_status {
 #define PM_QOS_FLAG_NO_POWER_OFF	(1 << 0)
 #define PM_QOS_FLAG_REMOTE_WAKEUP	(1 << 1)
 
+enum pm_qos_req_type {
+	PM_QOS_REQ_ALL_CORES = 0,
+	PM_QOS_REQ_AFFINE_CORES,
+	PM_QOS_REQ_AFFINE_IRQ,
+};
+
 struct pm_qos_request {
+	enum pm_qos_req_type type;
+	struct cpumask cpus_affine;
+	uint32_t irq;
+	/* Internal structure members */
+	struct irq_affinity_notify irq_notify;
 	struct plist_node node;
 	int pm_qos_class;
 	struct delayed_work work; /* for pm_qos_update_request_timeout */
@@ -80,6 +93,7 @@  enum pm_qos_type {
 struct pm_qos_constraints {
 	struct plist_head list;
 	s32 target_value;	/* Do not change to 64 bit */
+	s32 target_per_cpu[NR_CPUS];
 	s32 default_value;
 	s32 no_constraint_value;
 	enum pm_qos_type type;
@@ -127,6 +141,8 @@  void pm_qos_update_request_timeout(struct pm_qos_request *req,
 void pm_qos_remove_request(struct pm_qos_request *req);
 
 int pm_qos_request(int pm_qos_class);
+int pm_qos_request_for_cpu(int pm_qos_class, int cpu);
+int pm_qos_request_for_cpumask(int pm_qos_class, struct cpumask *mask);
 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
 int pm_qos_request_active(struct pm_qos_request *req);
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index d0b9c0f..92d8521 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -41,6 +41,9 @@ 
 #include <linux/platform_device.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/delay.h>
 
 #include <linux/uaccess.h>
 #include <linux/export.h>
@@ -65,6 +68,8 @@  static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
 static struct pm_qos_constraints cpu_dma_constraints = {
 	.list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
 	.target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
+	.target_per_cpu = { [0 ... (NR_CPUS - 1)] =
+				PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE },
 	.default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
 	.no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
 	.type = PM_QOS_MIN,
@@ -79,6 +84,8 @@  static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
 static struct pm_qos_constraints network_lat_constraints = {
 	.list = PLIST_HEAD_INIT(network_lat_constraints.list),
 	.target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
+	.target_per_cpu = { [0 ... (NR_CPUS - 1)] =
+				PM_QOS_NETWORK_LAT_DEFAULT_VALUE },
 	.default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
 	.no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
 	.type = PM_QOS_MIN,
@@ -94,6 +101,8 @@  static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
 static struct pm_qos_constraints network_tput_constraints = {
 	.list = PLIST_HEAD_INIT(network_tput_constraints.list),
 	.target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
+	.target_per_cpu = { [0 ... (NR_CPUS - 1)] =
+				PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE },
 	.default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 	.no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 	.type = PM_QOS_MAX,
@@ -157,6 +166,34 @@  static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 	c->target_value = value;
 }
 
+static inline void pm_qos_set_value_for_cpus(struct pm_qos_constraints *c)
+{
+	struct pm_qos_request *req = NULL;
+	int cpu;
+	s32 qos_val[NR_CPUS] = { [0 ... (NR_CPUS - 1)] = c->default_value };
+
+	plist_for_each_entry(req, &c->list, node) {
+		for_each_cpu(cpu, &req->cpus_affine) {
+			switch (c->type) {
+			case PM_QOS_MIN:
+				if (qos_val[cpu] > req->node.prio)
+					qos_val[cpu] = req->node.prio;
+				break;
+			case PM_QOS_MAX:
+				if (req->node.prio > qos_val[cpu])
+					qos_val[cpu] = req->node.prio;
+				break;
+			default:
+				BUG();
+				break;
+			}
+		}
+	}
+
+	for_each_possible_cpu(cpu)
+		c->target_per_cpu[cpu] = qos_val[cpu];
+}
+
 /**
  * pm_qos_update_target - manages the constraints list and calls the notifiers
  *  if needed
@@ -206,6 +243,7 @@  int pm_qos_update_target(struct pm_qos_constraints *c,
 
 	curr_value = pm_qos_get_value(c);
 	pm_qos_set_value(c, curr_value);
+	pm_qos_set_value_for_cpus(c);
 
 	spin_unlock_irqrestore(&pm_qos_lock, flags);
 
@@ -298,6 +336,44 @@  int pm_qos_request(int pm_qos_class)
 }
 EXPORT_SYMBOL_GPL(pm_qos_request);
 
+int pm_qos_request_for_cpu(int pm_qos_class, int cpu)
+{
+	return pm_qos_array[pm_qos_class]->constraints->target_per_cpu[cpu];
+}
+EXPORT_SYMBOL(pm_qos_request_for_cpu);
+
+int pm_qos_request_for_cpumask(int pm_qos_class, struct cpumask *mask)
+{
+	unsigned long irqflags;
+	int cpu;
+	struct pm_qos_constraints *c = NULL;
+	int val;
+
+	spin_lock_irqsave(&pm_qos_lock, irqflags);
+	c = pm_qos_array[pm_qos_class]->constraints;
+	val = c->default_value;
+
+	for_each_cpu(cpu, mask) {
+		switch (c->type) {
+		case PM_QOS_MIN:
+			if (c->target_per_cpu[cpu] < val)
+				val = c->target_per_cpu[cpu];
+			break;
+		case PM_QOS_MAX:
+			if (c->target_per_cpu[cpu] > val)
+				val = c->target_per_cpu[cpu];
+			break;
+		default:
+			BUG();
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&pm_qos_lock, irqflags);
+
+	return val;
+}
+EXPORT_SYMBOL(pm_qos_request_for_cpumask);
+
 int pm_qos_request_active(struct pm_qos_request *req)
 {
 	return req->pm_qos_class != 0;
@@ -330,6 +406,35 @@  static void pm_qos_work_fn(struct work_struct *work)
 	__pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
 }
 
+static void pm_qos_irq_release(struct kref *ref)
+{
+	unsigned long flags;
+	struct irq_affinity_notify *notify = container_of(ref,
+			struct irq_affinity_notify, kref);
+	struct pm_qos_request *req = container_of(notify,
+			struct pm_qos_request, irq_notify);
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	cpumask_clear(&req->cpus_affine);
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+}
+
+static void pm_qos_irq_notify(struct irq_affinity_notify *notify,
+		const cpumask_t *mask)
+{
+	unsigned long flags;
+	struct pm_qos_request *req = container_of(notify,
+			struct pm_qos_request, irq_notify);
+	struct pm_qos_constraints *c =
+		pm_qos_array[req->pm_qos_class]->constraints;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	cpumask_copy(&req->cpus_affine, mask);
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+	pm_qos_update_target(c, req, PM_QOS_UPDATE_REQ, req->node.prio);
+}
+
 /**
  * pm_qos_add_request - inserts new qos request into the list
  * @req: pointer to a preallocated handle
@@ -353,6 +458,51 @@  void pm_qos_add_request(struct pm_qos_request *req,
 		WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
 		return;
 	}
+
+	switch (req->type) {
+	case PM_QOS_REQ_AFFINE_CORES:
+		if (cpumask_empty(&req->cpus_affine)) {
+			req->type = PM_QOS_REQ_ALL_CORES;
+			cpumask_setall(&req->cpus_affine);
+			WARN(1, KERN_ERR "Affine cores not set for request with affinity flag\n");
+		}
+		break;
+
+	case PM_QOS_REQ_AFFINE_IRQ:
+		if (irq_can_set_affinity(req->irq)) {
+			int ret = 0;
+			struct irq_desc *desc = irq_to_desc(req->irq);
+			struct cpumask *mask = desc->irq_data.affinity;
+
+			/* Get the current affinity */
+			cpumask_copy(&req->cpus_affine, mask);
+			req->irq_notify.irq = req->irq;
+			req->irq_notify.notify = pm_qos_irq_notify;
+			req->irq_notify.release = pm_qos_irq_release;
+
+			ret = irq_set_affinity_notifier(req->irq,
+					&req->irq_notify);
+			if (ret) {
+				WARN(1, KERN_ERR "IRQ affinity notify set failed\n");
+				req->type = PM_QOS_REQ_ALL_CORES;
+				cpumask_setall(&req->cpus_affine);
+			}
+		} else {
+			req->type = PM_QOS_REQ_ALL_CORES;
+			cpumask_setall(&req->cpus_affine);
+			WARN(1, KERN_ERR "IRQ-%d not set for request with affinity flag\n",
+					req->irq);
+		}
+		break;
+
+	default:
+		WARN(1, KERN_ERR "Unknown request type %d\n", req->type);
+		/* fall through */
+	case PM_QOS_REQ_ALL_CORES:
+		cpumask_setall(&req->cpus_affine);
+		break;
+	}
+
 	req->pm_qos_class = pm_qos_class;
 	INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
 	trace_pm_qos_add_request(pm_qos_class, value);
@@ -426,10 +576,16 @@  void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
  */
 void pm_qos_remove_request(struct pm_qos_request *req)
 {
+	int count = 10;
+
 	if (!req) /*guard against callers passing in null */
 		return;
 		/* silent return to keep pcm code cleaner */
 
+	/* Remove ourselves from the irq notification */
+	if (req->type == PM_QOS_REQ_AFFINE_IRQ)
+		irq_release_affinity_notifier(&req->irq_notify);
+
 	if (!pm_qos_request_active(req)) {
 		WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
 		return;
@@ -441,6 +597,20 @@  void pm_qos_remove_request(struct pm_qos_request *req)
 	pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
 			     req, PM_QOS_REMOVE_REQ,
 			     PM_QOS_DEFAULT_VALUE);
+
+	/**
+	 * The 'release' callback of the notifier would not be called unless
+	 * there are no active users of the irq_notify object, i.e, kref count
+	 * is non-zero. This could happen if there is an active 'notify'
+	 * callback happening while the pm_qos_remove request is called. Wait
+	 * until the release callback clears the cpus_affine mask.
+	 */
+	if (req->type == PM_QOS_REQ_AFFINE_IRQ) {
+		while (!cpumask_empty(&req->cpus_affine) && count--)
+			msleep(50);
+		BUG_ON(!count);
+	}
+
 	memset(req, 0, sizeof(*req));
 }
 EXPORT_SYMBOL_GPL(pm_qos_remove_request);