* 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
+ * 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.
* timeout: usec <-- currently not used.
* throughput: kbs (kilo byte / sec)
*
- * There are lists of pm_qos_objects each one wrapping requirements, notifiers
+ * There are lists of pm_qos_objects each one wrapping requests, notifiers
*
- * User mode requirements on a QOS parameter register themselves to the
+ * 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
- * 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
+ * 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_params.h>
#include <linux/sched.h>
-#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/uaccess.h>
/*
- * locking rule: all changes to requirements or notifiers lists
+ * locking rule: all changes to requests 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;
+enum pm_qos_type {
+ PM_QOS_MAX, /* return the largest value */
+ PM_QOS_MIN /* return the smallest value */
};
-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 plist_head requests;
struct blocking_notifier_head *notifiers;
struct miscdevice pm_qos_power_miscdev;
char *name;
s32 default_value;
- atomic_t target_value;
- s32 (*comparitor)(s32, s32);
+ enum pm_qos_type type;
};
+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_object cpu_dma_pm_qos = {
- .requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)},
+ .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
.notifiers = &cpu_dma_lat_notifier,
.name = "cpu_dma_latency",
.default_value = 2000 * USEC_PER_SEC,
- .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
- .comparitor = min_compare
+ .type = PM_QOS_MIN,
};
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)},
+ .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
.notifiers = &network_lat_notifier,
.name = "network_latency",
.default_value = 2000 * USEC_PER_SEC,
- .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
- .comparitor = min_compare
+ .type = PM_QOS_MIN
};
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)},
+ .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
.notifiers = &network_throughput_notifier,
.name = "network_throughput",
.default_value = 0,
- .target_value = ATOMIC_INIT(0),
- .comparitor = max_compare
+ .type = PM_QOS_MAX,
};
&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 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,
};
-/* static helper functions */
-static s32 max_compare(s32 v1, s32 v2)
+/* unlocked internal variant */
+static inline int pm_qos_get_value(struct pm_qos_object *o)
{
- return max(v1, v2);
-}
+ if (plist_head_empty(&o->requests))
+ return o->default_value;
-static s32 min_compare(s32 v1, s32 v2)
-{
- return min(v1, v2);
-}
+ switch (o->type) {
+ case PM_QOS_MIN:
+ return plist_first(&o->requests)->prio;
+ case PM_QOS_MAX:
+ return plist_last(&o->requests)->prio;
-static void update_target(int target)
+ default:
+ /* runtime check for not using enum */
+ BUG();
+ }
+}
+
+static void update_target(struct pm_qos_object *o, struct plist_node *node,
+ int del, int value)
{
- s32 extreme_value;
- struct requirement_list *node;
unsigned long flags;
- int call_notifier = 0;
+ int prev_value, curr_value;
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 (atomic_read(&pm_qos_array[target]->target_value) != extreme_value) {
- call_notifier = 1;
- atomic_set(&pm_qos_array[target]->target_value, extreme_value);
- pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
- atomic_read(&pm_qos_array[target]->target_value));
+ prev_value = pm_qos_get_value(o);
+ /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
+ if (value != PM_QOS_DEFAULT_VALUE) {
+ /*
+ * to change the list, we atomically remove, reinit
+ * with new value and add, then see if the extremal
+ * changed
+ */
+ plist_del(node, &o->requests);
+ plist_node_init(node, value);
+ plist_add(node, &o->requests);
+ } else if (del) {
+ plist_del(node, &o->requests);
+ } else {
+ plist_add(node, &o->requests);
}
+ curr_value = pm_qos_get_value(o);
spin_unlock_irqrestore(&pm_qos_lock, flags);
- if (call_notifier)
- blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
- (unsigned long) extreme_value, NULL);
+ if (prev_value != curr_value)
+ blocking_notifier_call_chain(o->notifiers,
+ (unsigned long)curr_value,
+ NULL);
}
static int register_pm_qos_misc(struct pm_qos_object *qos)
}
/**
- * pm_qos_requirement - returns current system wide qos expectation
+ * 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 in an atomic manner.
*/
-int pm_qos_requirement(int pm_qos_class)
+int pm_qos_request(int pm_qos_class)
{
- return atomic_read(&pm_qos_array[pm_qos_class]->target_value);
+ unsigned long flags;
+ int value;
+
+ spin_lock_irqsave(&pm_qos_lock, flags);
+ value = pm_qos_get_value(pm_qos_array[pm_qos_class]);
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+ return value;
+}
+EXPORT_SYMBOL_GPL(pm_qos_request);
+
+int pm_qos_request_active(struct pm_qos_request_list *req)
+{
+ return req->pm_qos_class != 0;
}
-EXPORT_SYMBOL_GPL(pm_qos_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_request_active);
/**
- * 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
+ * pm_qos_add_request - inserts new qos request into the list
+ * @dep: 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.
+ * for the pm_qos_class of parameters and initializes the pm_qos_request_list
+ * handle. Caller needs to save this handle for later use in updates and
+ * removal.
*/
-int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value)
+
+void pm_qos_add_request(struct pm_qos_request_list *dep,
+ int pm_qos_class, s32 value)
{
- struct requirement_list *dep;
- unsigned long flags;
+ struct pm_qos_object *o = pm_qos_array[pm_qos_class];
+ int new_value;
- 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;
+ if (pm_qos_request_active(dep)) {
+ WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
+ return;
}
-
-cleanup:
- kfree(dep);
- return -ENOMEM;
+ if (value == PM_QOS_DEFAULT_VALUE)
+ new_value = o->default_value;
+ else
+ new_value = value;
+ plist_node_init(&dep->list, new_value);
+ dep->pm_qos_class = pm_qos_class;
+ update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE);
}
-EXPORT_SYMBOL_GPL(pm_qos_add_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_add_request);
/**
- * pm_qos_update_requirement - modifies an existing qos request
- * @pm_qos_class: identifies which list of qos request to us
- * @name: identifies the request
+ * pm_qos_update_request - modifies an existing qos request
+ * @pm_qos_req : handle to list element holding a pm_qos request to use
* @value: defines the qos request
*
- * Updates an existing qos requirement for the pm_qos_class of parameters along
+ * Updates an existing qos request for the pm_qos_class of parameters along
* with updating the target pm_qos_class value.
*
- * If the named request isn't in the list then no change is made.
+ * Attempts are made to make this code callable on hot code paths.
*/
-int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value)
+void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
+ s32 new_value)
{
- unsigned long flags;
- struct requirement_list *node;
- int pending_update = 0;
+ s32 temp;
+ struct pm_qos_object *o;
- 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;
- }
+ if (!pm_qos_req) /*guard against callers passing in null */
+ return;
+
+ if (!pm_qos_request_active(pm_qos_req)) {
+ WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
+ return;
}
- spin_unlock_irqrestore(&pm_qos_lock, flags);
- if (pending_update)
- update_target(pm_qos_class);
- return 0;
+ o = pm_qos_array[pm_qos_req->pm_qos_class];
+
+ if (new_value == PM_QOS_DEFAULT_VALUE)
+ temp = o->default_value;
+ else
+ temp = new_value;
+
+ if (temp != pm_qos_req->list.prio)
+ update_target(o, &pm_qos_req->list, 0, temp);
}
-EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_update_request);
/**
- * pm_qos_remove_requirement - modifies an existing qos request
- * @pm_qos_class: identifies which list of qos request to us
- * @name: identifies the request
+ * pm_qos_remove_request - modifies an existing qos request
+ * @pm_qos_req: handle to request list element
*
- * Will remove named qos request from pm_qos_class list of parameters and
- * recompute the current target value for the pm_qos_class.
+ * Will remove pm qos request from the list of requests and
+ * recompute the current target value for the pm_qos_class. Call this
+ * on slow code paths.
*/
-void pm_qos_remove_requirement(int pm_qos_class, char *name)
+void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
{
- unsigned long flags;
- struct requirement_list *node;
- int pending_update = 0;
+ struct pm_qos_object *o;
- 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;
- }
+ if (pm_qos_req == NULL)
+ return;
+ /* silent return to keep pcm code cleaner */
+
+ if (!pm_qos_request_active(pm_qos_req)) {
+ WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
+ return;
}
- spin_unlock_irqrestore(&pm_qos_lock, flags);
- if (pending_update)
- update_target(pm_qos_class);
+
+ o = pm_qos_array[pm_qos_req->pm_qos_class];
+ update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
+ memset(pm_qos_req, 0, sizeof(*pm_qos_req));
}
-EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);
+EXPORT_SYMBOL_GPL(pm_qos_remove_request);
/**
* pm_qos_add_notifier - sets notification entry for changes to target value
* 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 pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
int 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;
- lock_kernel();
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) {
- unlock_kernel();
+ struct pm_qos_request_list *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;
- }
}
- unlock_kernel();
-
return -EPERM;
}
static int pm_qos_power_release(struct inode *inode, struct file *filp)
{
- int pm_qos_class;
+ struct pm_qos_request_list *req;
- pm_qos_class = (long)filp->private_data;
- sprintf(name, "process_%d", current->pid);
- pm_qos_remove_requirement(pm_qos_class, name);
+ req = filp->private_data;
+ pm_qos_remove_request(req);
+ kfree(req);
return 0;
}
-static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
+
+static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
size_t count, loff_t *f_pos)
{
s32 value;
- int pm_qos_class;
+ unsigned long flags;
+ struct pm_qos_object *o;
+ struct pm_qos_request_list *pm_qos_req = filp->private_data;;
- pm_qos_class = (long)filp->private_data;
- if (count != sizeof(s32))
+ if (!pm_qos_req)
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);
+ if (!pm_qos_request_active(pm_qos_req))
+ return -EINVAL;
+
+ o = pm_qos_array[pm_qos_req->pm_qos_class];
+ spin_lock_irqsave(&pm_qos_lock, flags);
+ value = pm_qos_get_value(o);
+ 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;
+ int x;
+ char ascii_value[11];
+ struct pm_qos_request_list *pm_qos_req;
+
+ if (count == sizeof(s32)) {
+ if (copy_from_user(&value, buf, sizeof(s32)))
+ return -EFAULT;
+ } else if (count == 11) { /* len('0x12345678/0') */
+ if (copy_from_user(ascii_value, buf, 11))
+ return -EFAULT;
+ if (strlen(ascii_value) != 10)
+ return -EINVAL;
+ x = sscanf(ascii_value, "%x", &value);
+ if (x != 1)
+ return -EINVAL;
+ pr_debug("%s, %d, 0x%x\n", ascii_value, x, value);
+ } else
+ return -EINVAL;
+
+ pm_qos_req = filp->private_data;
+ pm_qos_update_request(pm_qos_req, value);
- return sizeof(s32);
+ return count;
}