1 files changed, 414 insertions, 0 deletions

diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
new file mode 100644
index 000000000000..86de6c50fc41
--- /dev/null
+++ b/drivers/base/power/qos.c
@@ -0,0 +1,414 @@
+/*
+ * Devices PM QoS constraints management
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ *
+ * This module exposes the interface to kernel space for specifying
+ * per-device PM QoS dependencies. It provides infrastructure for registration
+ * of:
+ *
+ * Dependents on a QoS value : register requests
+ * Watchers of QoS value : get notified when target QoS value changes
+ *
+ * This QoS design is best effort based. Dependents register their QoS needs.
+ * Watchers register to keep track of the current QoS needs of the system.
+ * Watchers can register different types of notification callbacks:
+ *  . a per-device notification callback using the dev_pm_qos_*_notifier API.
+ *    The notification chain data is stored in the per-device constraint
+ *    data struct.
+ *  . a system-wide notification callback using the dev_pm_qos_*_global_notifier
+ *    API. The notification chain data is stored in a static variable.
+ *
+ * Note about the per-device constraint data struct allocation:
+ * . The per-device constraints data struct ptr is tored into the device
+ *    dev_pm_info.
+ * . To minimize the data usage by the per-device constraints, the data struct
+ *   is only allocated at the first call to dev_pm_qos_add_request.
+ * . The data is later free'd when the device is removed from the system.
+ *  . A global mutex protects the constraints users from the data being
+ *     allocated and free'd.
+ */
+
+#include <linux/pm_qos.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/export.h>
+
+
+static DEFINE_MUTEX(dev_pm_qos_mtx);
+
+static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
+
+/**
+ * dev_pm_qos_read_value - Get PM QoS constraint for a given device.
+ * @dev: Device to get the PM QoS constraint value for.
+ */
+s32 dev_pm_qos_read_value(struct device *dev)
+{
+        struct pm_qos_constraints *c;
+        unsigned long flags;
+        s32 ret = 0;
+
+        spin_lock_irqsave(&dev->power.lock, flags);
+
+        c = dev->power.constraints;
+        if (c)
+                ret = pm_qos_read_value(c);
+
+        spin_unlock_irqrestore(&dev->power.lock, flags);
+
+        return ret;
+}
+
+/*
+ * apply_constraint
+ * @req: constraint request to apply
+ * @action: action to perform add/update/remove, of type enum pm_qos_req_action
+ * @value: defines the qos request
+ *
+ * Internal function to update the constraints list using the PM QoS core
+ * code and if needed call the per-device and the global notification
+ * callbacks
+ */
+static int apply_constraint(struct dev_pm_qos_request *req,
+                            enum pm_qos_req_action action, int value)
+{
+        int ret, curr_value;
+
+        ret = pm_qos_update_target(req->dev->power.constraints,
+                                   &req->node, action, value);
+
+        if (ret) {
+                /* Call the global callbacks if needed */
+                curr_value = pm_qos_read_value(req->dev->power.constraints);
+                blocking_notifier_call_chain(&dev_pm_notifiers,
+                                             (unsigned long)curr_value,
+                                             req);
+        }
+
+        return ret;
+}
+
+/*
+ * dev_pm_qos_constraints_allocate
+ * @dev: device to allocate data for
+ *
+ * Called at the first call to add_request, for constraint data allocation
+ * Must be called with the dev_pm_qos_mtx mutex held
+ */
+static int dev_pm_qos_constraints_allocate(struct device *dev)
+{
+        struct pm_qos_constraints *c;
+        struct blocking_notifier_head *n;
+
+        c = kzalloc(sizeof(*c), GFP_KERNEL);
+        if (!c)
+                return -ENOMEM;
+
+        n = kzalloc(sizeof(*n), GFP_KERNEL);
+        if (!n) {
+                kfree(c);
+                return -ENOMEM;
+        }
+        BLOCKING_INIT_NOTIFIER_HEAD(n);
+
+        plist_head_init(&c->list);
+        c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+        c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+        c->type = PM_QOS_MIN;
+        c->notifiers = n;
+
+        spin_lock_irq(&dev->power.lock);
+        dev->power.constraints = c;
+        spin_unlock_irq(&dev->power.lock);
+
+        return 0;
+}
+
+/**
+ * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
+ * @dev: target device
+ *
+ * Called from the device PM subsystem during device insertion under
+ * device_pm_lock().
+ */
+void dev_pm_qos_constraints_init(struct device *dev)
+{
+        mutex_lock(&dev_pm_qos_mtx);
+        dev->power.constraints = NULL;
+        dev->power.power_state = PMSG_ON;
+        mutex_unlock(&dev_pm_qos_mtx);
+}
+
+/**
+ * dev_pm_qos_constraints_destroy
+ * @dev: target device
+ *
+ * Called from the device PM subsystem on device removal under device_pm_lock().
+ */
+void dev_pm_qos_constraints_destroy(struct device *dev)
+{
+        struct dev_pm_qos_request *req, *tmp;
+        struct pm_qos_constraints *c;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        dev->power.power_state = PMSG_INVALID;
+        c = dev->power.constraints;
+        if (!c)
+                goto out;
+
+        /* Flush the constraints list for the device */
+        plist_for_each_entry_safe(req, tmp, &c->list, node) {
+                /*
+                 * Update constraints list and call the notification
+                 * callbacks if needed
+                 */
+                apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
+                memset(req, 0, sizeof(*req));
+        }
+
+        spin_lock_irq(&dev->power.lock);
+        dev->power.constraints = NULL;
+        spin_unlock_irq(&dev->power.lock);
+
+        kfree(c->notifiers);
+        kfree(c);
+
+ out:
+        mutex_unlock(&dev_pm_qos_mtx);
+}
+
+/**
+ * dev_pm_qos_add_request - inserts new qos request into the list
+ * @dev: target device for the constraint
+ * @req: pointer to a preallocated handle
+ * @value: defines the qos request
+ *
+ * This function inserts a new entry in the device constraints list of
+ * requested qos performance characteristics. It recomputes the aggregate
+ * QoS expectations of parameters and initializes the dev_pm_qos_request
+ * handle.  Caller needs to save this handle for later use in updates and
+ * removal.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory
+ * to allocate for data structures, -ENODEV if the device has just been removed
+ * from the system.
+ */
+int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
+                           s32 value)
+{
+        int ret = 0;
+
+        if (!dev || !req) /*guard against callers passing in null */
+                return -EINVAL;
+
+        if (WARN(dev_pm_qos_request_active(req),
+                 "%s() called for already added request\n", __func__))
+                return -EINVAL;
+
+        req->dev = dev;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        if (!dev->power.constraints) {
+                if (dev->power.power_state.event == PM_EVENT_INVALID) {
+                        /* The device has been removed from the system. */
+                        req->dev = NULL;
+                        ret = -ENODEV;
+                        goto out;
+                } else {
+                        /*
+                         * Allocate the constraints data on the first call to
+                         * add_request, i.e. only if the data is not already
+                         * allocated and if the device has not been removed.
+                         */
+                        ret = dev_pm_qos_constraints_allocate(dev);
+                }
+        }
+
+        if (!ret)
+                ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
+
+ out:
+        mutex_unlock(&dev_pm_qos_mtx);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
+
+/**
+ * dev_pm_qos_update_request - modifies an existing qos request
+ * @req : handle to list element holding a dev_pm_qos request to use
+ * @new_value: defines the qos request
+ *
+ * Updates an existing dev PM qos request along with updating the
+ * target value.
+ *
+ * Attempts are made to make this code callable on hot code paths.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENODEV if the device has been
+ * removed from the system
+ */
+int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
+                              s32 new_value)
+{
+        int ret = 0;
+
+        if (!req) /*guard against callers passing in null */
+                return -EINVAL;
+
+        if (WARN(!dev_pm_qos_request_active(req),
+                 "%s() called for unknown object\n", __func__))
+                return -EINVAL;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        if (req->dev->power.constraints) {
+                if (new_value != req->node.prio)
+                        ret = apply_constraint(req, PM_QOS_UPDATE_REQ,
+                                               new_value);
+        } else {
+                /* Return if the device has been removed */
+                ret = -ENODEV;
+        }
+
+        mutex_unlock(&dev_pm_qos_mtx);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
+
+/**
+ * dev_pm_qos_remove_request - modifies an existing qos request
+ * @req: handle to request list element
+ *
+ * Will remove pm qos request from the list of constraints and
+ * recompute the current target value. Call this on slow code paths.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENODEV if the device has been
+ * removed from the system
+ */
+int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
+{
+        int ret = 0;
+
+        if (!req) /*guard against callers passing in null */
+                return -EINVAL;
+
+        if (WARN(!dev_pm_qos_request_active(req),
+                 "%s() called for unknown object\n", __func__))
+                return -EINVAL;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        if (req->dev->power.constraints) {
+                ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
+                                       PM_QOS_DEFAULT_VALUE);
+                memset(req, 0, sizeof(*req));
+        } else {
+                /* Return if the device has been removed */
+                ret = -ENODEV;
+        }
+
+        mutex_unlock(&dev_pm_qos_mtx);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
+
+/**
+ * dev_pm_qos_add_notifier - sets notification entry for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for the device.
+ */
+int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
+{
+        int retval = 0;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        /* Silently return if the constraints object is not present. */
+        if (dev->power.constraints)
+                retval = blocking_notifier_chain_register(
+                                dev->power.constraints->notifiers,
+                                notifier);
+
+        mutex_unlock(&dev_pm_qos_mtx);
+        return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
+
+/**
+ * dev_pm_qos_remove_notifier - deletes notification for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value.
+ */
+int dev_pm_qos_remove_notifier(struct device *dev,
+                               struct notifier_block *notifier)
+{
+        int retval = 0;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        /* Silently return if the constraints object is not present. */
+        if (dev->power.constraints)
+                retval = blocking_notifier_chain_unregister(
+                                dev->power.constraints->notifiers,
+                                notifier);
+
+        mutex_unlock(&dev_pm_qos_mtx);
+        return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
+
+/**
+ * dev_pm_qos_add_global_notifier - sets notification entry for changes to
+ * target value of the PM QoS constraints for any device
+ *
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
+{
+        return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
+
+/**
+ * dev_pm_qos_remove_global_notifier - deletes notification for changes to
+ * target value of PM QoS constraints for any device
+ *
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
+{
+        return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);