Initial commit

kernel/pm_qos_params.c

@@ -0,0 +1,425 @@
+/*
+ * This module exposes the interface to kernel space for specifying
+ * QoS dependencies.  It provides infrastructure for registration of:
+ *
+ * Dependents on a QoS value : register requirements
+ * 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.
+ *
+ * There are 3 basic classes of QoS parameter: latency, timeout, throughput
+ * each have defined units:
+ * latency: usec
+ * timeout: usec <-- currently not used.
+ * throughput: kbs (kilo byte / sec)
+ *
+ * There are lists of pm_qos_objects each one wrapping requirements, notifiers
+ *
+ * User mode requirements on a QOS parameter register themselves to the
+ * subsystem by opening the device node /dev/... and writing there request to
+ * the node.  As long as the process holds a file handle open to the node the
+ * client continues to be accounted for.  Upon file release the usermode
+ * requirement is removed and a new qos target is computed.  This way when the
+ * requirement that the application has is cleaned up when closes the file
+ * pointer or exits the pm_qos_object will get an opportunity to clean up.
+ *
+ * mark gross mgross@linux.intel.com
+ */
+
+#include <linux/pm_qos_params.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/string.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+
+#include <linux/uaccess.h>
+
+/*
+ * locking rule: all changes to target_value or requirements or notifiers lists
+ * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
+ * held, taken with _irqsave.  One lock to rule them all
+ */
+struct requirement_list {
+	struct list_head list;
+	union {
+		s32 value;
+		s32 usec;
+		s32 kbps;
+	};
+	char *name;
+};
+
+static s32 max_compare(s32 v1, s32 v2);
+static s32 min_compare(s32 v1, s32 v2);
+
+struct pm_qos_object {
+	struct requirement_list requirements;
+	struct blocking_notifier_head *notifiers;
+	struct miscdevice pm_qos_power_miscdev;
+	char *name;
+	s32 default_value;
+	s32 target_value;
+	s32 (*comparitor)(s32, s32);
+};
+
+static struct pm_qos_object null_pm_qos;
+static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
+static struct pm_qos_object cpu_dma_pm_qos = {
+	.requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
+	.notifiers = &cpu_dma_lat_notifier,
+	.name = "cpu_dma_latency",
+	.default_value = 2000 * USEC_PER_SEC,
+	.target_value = 2000 * USEC_PER_SEC,
+	.comparitor = min_compare
+};
+
+static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
+static struct pm_qos_object network_lat_pm_qos = {
+	.requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)},
+	.notifiers = &network_lat_notifier,
+	.name = "network_latency",
+	.default_value = 2000 * USEC_PER_SEC,
+	.target_value = 2000 * USEC_PER_SEC,
+	.comparitor = min_compare
+};
+
+
+static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
+static struct pm_qos_object network_throughput_pm_qos = {
+	.requirements =
+		{LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)},
+	.notifiers = &network_throughput_notifier,
+	.name = "network_throughput",
+	.default_value = 0,
+	.target_value = 0,
+	.comparitor = max_compare
+};
+
+
+static struct pm_qos_object *pm_qos_array[] = {
+	&null_pm_qos,
+	&cpu_dma_pm_qos,
+	&network_lat_pm_qos,
+	&network_throughput_pm_qos
+};
+
+static DEFINE_SPINLOCK(pm_qos_lock);
+
+static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
+		size_t count, loff_t *f_pos);
+static int pm_qos_power_open(struct inode *inode, struct file *filp);
+static int pm_qos_power_release(struct inode *inode, struct file *filp);
+
+static const struct file_operations pm_qos_power_fops = {
+	.write = pm_qos_power_write,
+	.open = pm_qos_power_open,
+	.release = pm_qos_power_release,
+};
+
+/* static helper functions */
+static s32 max_compare(s32 v1, s32 v2)
+{
+	return max(v1, v2);
+}
+
+static s32 min_compare(s32 v1, s32 v2)
+{
+	return min(v1, v2);
+}
+
+
+static void update_target(int target)
+{
+	s32 extreme_value;
+	struct requirement_list *node;
+	unsigned long flags;
+	int call_notifier = 0;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	extreme_value = pm_qos_array[target]->default_value;
+	list_for_each_entry(node,
+			&pm_qos_array[target]->requirements.list, list) {
+		extreme_value = pm_qos_array[target]->comparitor(
+				extreme_value, node->value);
+	}
+	if (pm_qos_array[target]->target_value != extreme_value) {
+		call_notifier = 1;
+		pm_qos_array[target]->target_value = extreme_value;
+		pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
+			pm_qos_array[target]->target_value);
+	}
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+	if (call_notifier)
+		blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
+			(unsigned long) extreme_value, NULL);
+}
+
+static int register_pm_qos_misc(struct pm_qos_object *qos)
+{
+	qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
+	qos->pm_qos_power_miscdev.name = qos->name;
+	qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
+
+	return misc_register(&qos->pm_qos_power_miscdev);
+}
+
+static int find_pm_qos_object_by_minor(int minor)
+{
+	int pm_qos_class;
+
+	for (pm_qos_class = 0;
+		pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
+		if (minor ==
+			pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
+			return pm_qos_class;
+	}
+	return -1;
+}
+
+/**
+ * pm_qos_requirement - returns current system wide qos expectation
+ * @pm_qos_class: identification of which qos value is requested
+ *
+ * This function returns the current target value in an atomic manner.
+ */
+int pm_qos_requirement(int pm_qos_class)
+{
+	int ret_val;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	ret_val = pm_qos_array[pm_qos_class]->target_value;
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+	return ret_val;
+}
+EXPORT_SYMBOL_GPL(pm_qos_requirement);
+
+/**
+ * pm_qos_add_requirement - inserts new qos request into the list
+ * @pm_qos_class: identifies which list of qos request to us
+ * @name: identifies the request
+ * @value: defines the qos request
+ *
+ * This function inserts a new entry in the pm_qos_class list of requested qos
+ * performance charactoistics.  It recomputes the agregate QoS expectations for
+ * the pm_qos_class of parrameters.
+ */
+int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
+{
+	struct requirement_list *dep;
+	unsigned long flags;
+
+	dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL);
+	if (dep) {
+		if (value == PM_QOS_DEFAULT_VALUE)
+			dep->value = pm_qos_array[pm_qos_class]->default_value;
+		else
+			dep->value = value;
+		dep->name = kstrdup(name, GFP_KERNEL);
+		if (!dep->name)
+			goto cleanup;
+
+		spin_lock_irqsave(&pm_qos_lock, flags);
+		list_add(&dep->list,
+			&pm_qos_array[pm_qos_class]->requirements.list);
+		spin_unlock_irqrestore(&pm_qos_lock, flags);
+		update_target(pm_qos_class);
+
+		return 0;
+	}
+
+cleanup:
+	kfree(dep);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
+
+/**
+ * pm_qos_update_requirement - modifies an existing qos request
+ * @pm_qos_class: identifies which list of qos request to us
+ * @name: identifies the request
+ * @value: defines the qos request
+ *
+ * Updates an existing qos requierement for the pm_qos_class of parameters along
+ * with updating the target pm_qos_class value.
+ *
+ * If the named request isn't in the lest then no change is made.
+ */
+int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
+{
+	unsigned long flags;
+	struct requirement_list *node;
+	int pending_update = 0;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	list_for_each_entry(node,
+		&pm_qos_array[pm_qos_class]->requirements.list, list) {
+		if (strcmp(node->name, name) == 0) {
+			if (new_value == PM_QOS_DEFAULT_VALUE)
+				node->value =
+				pm_qos_array[pm_qos_class]->default_value;
+			else
+				node->value = new_value;
+			pending_update = 1;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+	if (pending_update)
+		update_target(pm_qos_class);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
+
+/**
+ * pm_qos_remove_requirement - modifies an existing qos request
+ * @pm_qos_class: identifies which list of qos request to us
+ * @name: identifies the request
+ *
+ * Will remove named qos request from pm_qos_class list of parrameters and
+ * recompute the current target value for the pm_qos_class.
+ */
+void pm_qos_remove_requirement(int pm_qos_class, char *name)
+{
+	unsigned long flags;
+	struct requirement_list *node;
+	int pending_update = 0;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	list_for_each_entry(node,
+		&pm_qos_array[pm_qos_class]->requirements.list, list) {
+		if (strcmp(node->name, name) == 0) {
+			kfree(node->name);
+			list_del(&node->list);
+			kfree(node);
+			pending_update = 1;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+	if (pending_update)
+		update_target(pm_qos_class);
+}
+EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
+
+/**
+ * pm_qos_add_notifier - sets notification entry for changes to target value
+ * @pm_qos_class: identifies which qos target changes should be notified.
+ * @notifier: notifier block managed by caller.
+ *
+ * will register the notifier into a notification chain that gets called
+ * uppon changes to the pm_qos_class target value.
+ */
+ int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
+{
+	int retval;
+
+	retval = blocking_notifier_chain_register(
+			pm_qos_array[pm_qos_class]->notifiers, notifier);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
+
+/**
+ * pm_qos_remove_notifier - deletes notification entry from chain.
+ * @pm_qos_class: identifies which qos target changes are notified.
+ * @notifier: notifier block to be removed.
+ *
+ * will remove the notifier from the notification chain that gets called
+ * uppon changes to the pm_qos_class target value.
+ */
+int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
+{
+	int retval;
+
+	retval = blocking_notifier_chain_unregister(
+			pm_qos_array[pm_qos_class]->notifiers, notifier);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
+
+#define PID_NAME_LEN sizeof("process_1234567890")
+static char name[PID_NAME_LEN];
+
+static int pm_qos_power_open(struct inode *inode, struct file *filp)
+{
+	int ret;
+	long pm_qos_class;
+
+	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
+	if (pm_qos_class >= 0) {
+		filp->private_data = (void *)pm_qos_class;
+		sprintf(name, "process_%d", current->pid);
+		ret = pm_qos_add_requirement(pm_qos_class, name,
+					PM_QOS_DEFAULT_VALUE);
+		if (ret >= 0)
+			return 0;
+	}
+
+	return -EPERM;
+}
+
+static int pm_qos_power_release(struct inode *inode, struct file *filp)
+{
+	int pm_qos_class;
+
+	pm_qos_class = (long)filp->private_data;
+	sprintf(name, "process_%d", current->pid);
+	pm_qos_remove_requirement(pm_qos_class, name);
+
+	return 0;
+}
+
+static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
+		size_t count, loff_t *f_pos)
+{
+	s32 value;
+	int pm_qos_class;
+
+	pm_qos_class = (long)filp->private_data;
+	if (count != sizeof(s32))
+		return -EINVAL;
+	if (copy_from_user(&value, buf, sizeof(s32)))
+		return -EFAULT;
+	sprintf(name, "process_%d", current->pid);
+	pm_qos_update_requirement(pm_qos_class, name, value);
+
+	return  sizeof(s32);
+}
+
+
+static int __init pm_qos_power_init(void)
+{
+	int ret = 0;
+
+	ret = register_pm_qos_misc(&cpu_dma_pm_qos);
+	if (ret < 0) {
+		printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
+		return ret;
+	}
+	ret = register_pm_qos_misc(&network_lat_pm_qos);
+	if (ret < 0) {
+		printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
+		return ret;
+	}
+	ret = register_pm_qos_misc(&network_throughput_pm_qos);
+	if (ret < 0)
+		printk(KERN_ERR
+			"pm_qos_param: network_throughput setup failed\n");
+
+	return ret;
+}
+
+late_initcall(pm_qos_power_init);