1 files changed, 490 insertions, 0 deletions
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
new file mode 100644
index 000000000000..1c1797dd1d1d
--- /dev/null
+++ b/kernel/power/qos.c
@@ -0,0 +1,490 @@
+/*
+ * This module exposes the interface to kernel space for specifying
+ * 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.
+ *
+ * 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 requests, notifiers
+ *
+ * User mode requests 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
+ * request is removed and a new qos target is computed.  This way when the
+ * request 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>
+ */
+
+/*#define DEBUG*/
+
+#include <linux/pm_qos.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/kernel.h>
+
+#include <linux/uaccess.h>
+
+/*
+ * locking rule: all changes to constraints 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 pm_qos_object {
+	struct pm_qos_constraints *constraints;
+	struct miscdevice pm_qos_power_miscdev;
+	char *name;
+};
+
+static DEFINE_SPINLOCK(pm_qos_lock);
+
+static struct pm_qos_object null_pm_qos;
+
+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,
+	.default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
+	.type = PM_QOS_MIN,
+	.notifiers = &cpu_dma_lat_notifier,
+};
+static struct pm_qos_object cpu_dma_pm_qos = {
+	.constraints = &cpu_dma_constraints,
+};
+
+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,
+	.default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
+	.type = PM_QOS_MIN,
+	.notifiers = &network_lat_notifier,
+};
+static struct pm_qos_object network_lat_pm_qos = {
+	.constraints = &network_lat_constraints,
+	.name = "network_latency",
+};
+
+
+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,
+	.default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
+	.type = PM_QOS_MAX,
+	.notifiers = &network_throughput_notifier,
+};
+static struct pm_qos_object network_throughput_pm_qos = {
+	.constraints = &network_tput_constraints,
+	.name = "network_throughput",
+};
+
+
+static struct pm_qos_object *pm_qos_array[] = {
+	&null_pm_qos,
+	&cpu_dma_pm_qos,
+	&network_lat_pm_qos,
+	&network_throughput_pm_qos
+};
+
+static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
+		size_t count, loff_t *f_pos);
+static ssize_t pm_qos_power_read(struct file *filp, 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,
+	.read = pm_qos_power_read,
+	.open = pm_qos_power_open,
+	.release = pm_qos_power_release,
+	.llseek = noop_llseek,
+};
+
+/* unlocked internal variant */
+static inline int pm_qos_get_value(struct pm_qos_constraints *c)
+{
+	if (plist_head_empty(&c->list))
+		return c->default_value;
+
+	switch (c->type) {
+	case PM_QOS_MIN:
+		return plist_first(&c->list)->prio;
+
+	case PM_QOS_MAX:
+		return plist_last(&c->list)->prio;
+
+	default:
+		/* runtime check for not using enum */
+		BUG();
+	}
+}
+
+s32 pm_qos_read_value(struct pm_qos_constraints *c)
+{
+	return c->target_value;
+}
+
+static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
+{
+	c->target_value = value;
+}
+
+/**
+ * pm_qos_update_target - manages the constraints list and calls the notifiers
+ *  if needed
+ * @c: constraints data struct
+ * @node: request to add to the list, to update or to remove
+ * @action: action to take on the constraints list
+ * @value: value of the request to add or update
+ *
+ * This function returns 1 if the aggregated constraint value has changed, 0
+ *  otherwise.
+ */
+int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
+			 enum pm_qos_req_action action, int value)
+{
+	unsigned long flags;
+	int prev_value, curr_value, new_value;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	prev_value = pm_qos_get_value(c);
+	if (value == PM_QOS_DEFAULT_VALUE)
+		new_value = c->default_value;
+	else
+		new_value = value;
+
+	switch (action) {
+	case PM_QOS_REMOVE_REQ:
+		plist_del(node, &c->list);
+		break;
+	case PM_QOS_UPDATE_REQ:
+		/*
+		 * to change the list, we atomically remove, reinit
+		 * with new value and add, then see if the extremal
+		 * changed
+		 */
+		plist_del(node, &c->list);
+	case PM_QOS_ADD_REQ:
+		plist_node_init(node, new_value);
+		plist_add(node, &c->list);
+		break;
+	default:
+		/* no action */
+		;
+	}
+
+	curr_value = pm_qos_get_value(c);
+	pm_qos_set_value(c, curr_value);
+
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+	if (prev_value != curr_value) {
+		blocking_notifier_call_chain(c->notifiers,
+					     (unsigned long)curr_value,
+					     NULL);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+/**
+ * pm_qos_request - returns current system wide qos expectation
+ * @pm_qos_class: identification of which qos value is requested
+ *
+ * This function returns the current target value.
+ */
+int pm_qos_request(int pm_qos_class)
+{
+	return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
+}
+EXPORT_SYMBOL_GPL(pm_qos_request);
+
+int pm_qos_request_active(struct pm_qos_request *req)
+{
+	return req->pm_qos_class != 0;
+}
+EXPORT_SYMBOL_GPL(pm_qos_request_active);
+
+/**
+ * pm_qos_add_request - inserts new qos request into the list
+ * @req: pointer to a preallocated handle
+ * @pm_qos_class: identifies which list of qos request to use
+ * @value: defines the qos request
+ *
+ * This function inserts a new entry in the pm_qos_class list of requested qos
+ * performance characteristics.  It recomputes the aggregate QoS expectations
+ * for the pm_qos_class of parameters and initializes the pm_qos_request
+ * handle.  Caller needs to save this handle for later use in updates and
+ * removal.
+ */
+
+void pm_qos_add_request(struct pm_qos_request *req,
+			int pm_qos_class, s32 value)
+{
+	if (!req) /*guard against callers passing in null */
+		return;
+
+	if (pm_qos_request_active(req)) {
+		WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
+		return;
+	}
+	req->pm_qos_class = pm_qos_class;
+	pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
+			     &req->node, PM_QOS_ADD_REQ, value);
+}
+EXPORT_SYMBOL_GPL(pm_qos_add_request);
+
+/**
+ * pm_qos_update_request - modifies an existing qos request
+ * @req : handle to list element holding a pm_qos request to use
+ * @value: defines the qos request
+ *
+ * Updates an existing qos request for the pm_qos_class of parameters along
+ * with updating the target pm_qos_class value.
+ *
+ * Attempts are made to make this code callable on hot code paths.
+ */
+void pm_qos_update_request(struct pm_qos_request *req,
+			   s32 new_value)
+{
+	if (!req) /*guard against callers passing in null */
+		return;
+
+	if (!pm_qos_request_active(req)) {
+		WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
+		return;
+	}
+
+	if (new_value != req->node.prio)
+		pm_qos_update_target(
+			pm_qos_array[req->pm_qos_class]->constraints,
+			&req->node, PM_QOS_UPDATE_REQ, new_value);
+}
+EXPORT_SYMBOL_GPL(pm_qos_update_request);
+
+/**
+ * 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 for the pm_qos_class.  Call this
+ * on slow code paths.
+ */
+void pm_qos_remove_request(struct pm_qos_request *req)
+{
+	if (!req) /*guard against callers passing in null */
+		return;
+		/* silent return to keep pcm code cleaner */
+
+	if (!pm_qos_request_active(req)) {
+		WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
+		return;
+	}
+
+	pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
+			     &req->node, PM_QOS_REMOVE_REQ,
+			     PM_QOS_DEFAULT_VALUE);
+	memset(req, 0, sizeof(*req));
+}
+EXPORT_SYMBOL_GPL(pm_qos_remove_request);
+
+/**
+ * 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
+ * upon 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]->constraints->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
+ * upon 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]->constraints->notifiers,
+			notifier);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
+
+/* User space interface to PM QoS classes via misc devices */
+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;
+}
+
+static int pm_qos_power_open(struct inode *inode, struct file *filp)
+{
+	long pm_qos_class;
+
+	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
+	if (pm_qos_class >= 0) {
+		struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
+		if (!req)
+			return -ENOMEM;
+
+		pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
+		filp->private_data = req;
+
+		if (filp->private_data)
+			return 0;
+	}
+	return -EPERM;
+}
+
+static int pm_qos_power_release(struct inode *inode, struct file *filp)
+{
+	struct pm_qos_request *req;
+
+	req = filp->private_data;
+	pm_qos_remove_request(req);
+	kfree(req);
+
+	return 0;
+}
+
+
+static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
+		size_t count, loff_t *f_pos)
+{
+	s32 value;
+	unsigned long flags;
+	struct pm_qos_request *req = filp->private_data;
+
+	if (!req)
+		return -EINVAL;
+	if (!pm_qos_request_active(req))
+		return -EINVAL;
+
+	spin_lock_irqsave(&pm_qos_lock, flags);
+	value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
+	spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+	return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
+}
+
+static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
+		size_t count, loff_t *f_pos)
+{
+	s32 value;
+	struct pm_qos_request *req;
+
+	if (count == sizeof(s32)) {
+		if (copy_from_user(&value, buf, sizeof(s32)))
+			return -EFAULT;
+	} else if (count <= 11) { /* ASCII perhaps? */
+		char ascii_value[11];
+		unsigned long int ulval;
+		int ret;
+
+		if (copy_from_user(ascii_value, buf, count))
+			return -EFAULT;
+
+		if (count > 10) {
+			if (ascii_value[10] == '\n')
+				ascii_value[10] = '\0';
+			else
+				return -EINVAL;
+		} else {
+			ascii_value[count] = '\0';
+		}
+		ret = strict_strtoul(ascii_value, 16, &ulval);
+		if (ret) {
+			pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
+			return -EINVAL;
+		}
+		value = (s32)lower_32_bits(ulval);
+	} else {
+		return -EINVAL;
+	}
+
+	req = filp->private_data;
+	pm_qos_update_request(req, value);
+
+	return count;
+}
+
+
+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);