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![Linus Torvalds](/assets/img/avatar_default.png)
* 'idle-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6: x86 idle: deprecate mwait_idle() and "idle=mwait" cmdline param x86 idle: deprecate "no-hlt" cmdline param x86 idle APM: deprecate CONFIG_APM_CPU_IDLE x86 idle floppy: deprecate disable_hlt() x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it x86 idle: clarify AMD erratum 400 workaround idle governor: Avoid lock acquisition to read pm_qos before entering idle cpuidle: menu: fixed wrapping timers at 4.294 seconds
481 lines
13 KiB
C
481 lines
13 KiB
C
/*
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* This module exposes the interface to kernel space for specifying
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* QoS dependencies. It provides infrastructure for registration of:
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*
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* Dependents on a QoS value : register requests
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* Watchers of QoS value : get notified when target QoS value changes
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*
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* This QoS design is best effort based. Dependents register their QoS needs.
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* Watchers register to keep track of the current QoS needs of the system.
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*
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* There are 3 basic classes of QoS parameter: latency, timeout, throughput
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* each have defined units:
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* latency: usec
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* timeout: usec <-- currently not used.
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* throughput: kbs (kilo byte / sec)
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*
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* There are lists of pm_qos_objects each one wrapping requests, notifiers
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*
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* User mode requests on a QOS parameter register themselves to the
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* subsystem by opening the device node /dev/... and writing there request to
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* the node. As long as the process holds a file handle open to the node the
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* client continues to be accounted for. Upon file release the usermode
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* request is removed and a new qos target is computed. This way when the
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* request that the application has is cleaned up when closes the file
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* pointer or exits the pm_qos_object will get an opportunity to clean up.
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*
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* Mark Gross <mgross@linux.intel.com>
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*/
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/*#define DEBUG*/
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#include <linux/pm_qos_params.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/miscdevice.h>
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#include <linux/string.h>
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#include <linux/platform_device.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/uaccess.h>
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/*
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* locking rule: all changes to requests or notifiers lists
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* or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
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* held, taken with _irqsave. One lock to rule them all
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*/
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enum pm_qos_type {
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PM_QOS_MAX, /* return the largest value */
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PM_QOS_MIN /* return the smallest value */
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};
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/*
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* Note: The lockless read path depends on the CPU accessing
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* target_value atomically. Atomic access is only guaranteed on all CPU
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* types linux supports for 32 bit quantites
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*/
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struct pm_qos_object {
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struct plist_head requests;
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struct blocking_notifier_head *notifiers;
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struct miscdevice pm_qos_power_miscdev;
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char *name;
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s32 target_value; /* Do not change to 64 bit */
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s32 default_value;
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enum pm_qos_type type;
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};
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static DEFINE_SPINLOCK(pm_qos_lock);
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static struct pm_qos_object null_pm_qos;
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static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
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static struct pm_qos_object cpu_dma_pm_qos = {
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.requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
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.notifiers = &cpu_dma_lat_notifier,
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.name = "cpu_dma_latency",
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.target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
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.default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
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.type = PM_QOS_MIN,
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};
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static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
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static struct pm_qos_object network_lat_pm_qos = {
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.requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
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.notifiers = &network_lat_notifier,
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.name = "network_latency",
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.target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
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.default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
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.type = PM_QOS_MIN
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};
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static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
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static struct pm_qos_object network_throughput_pm_qos = {
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.requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
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.notifiers = &network_throughput_notifier,
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.name = "network_throughput",
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.target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
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.default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
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.type = PM_QOS_MAX,
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};
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static struct pm_qos_object *pm_qos_array[] = {
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&null_pm_qos,
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&cpu_dma_pm_qos,
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&network_lat_pm_qos,
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&network_throughput_pm_qos
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};
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static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *f_pos);
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static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
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size_t count, loff_t *f_pos);
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static int pm_qos_power_open(struct inode *inode, struct file *filp);
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static int pm_qos_power_release(struct inode *inode, struct file *filp);
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static const struct file_operations pm_qos_power_fops = {
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.write = pm_qos_power_write,
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.read = pm_qos_power_read,
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.open = pm_qos_power_open,
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.release = pm_qos_power_release,
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.llseek = noop_llseek,
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};
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/* unlocked internal variant */
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static inline int pm_qos_get_value(struct pm_qos_object *o)
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{
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if (plist_head_empty(&o->requests))
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return o->default_value;
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switch (o->type) {
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case PM_QOS_MIN:
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return plist_first(&o->requests)->prio;
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case PM_QOS_MAX:
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return plist_last(&o->requests)->prio;
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default:
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/* runtime check for not using enum */
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BUG();
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}
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}
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static inline s32 pm_qos_read_value(struct pm_qos_object *o)
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{
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return o->target_value;
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}
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static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value)
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{
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o->target_value = value;
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}
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static void update_target(struct pm_qos_object *o, struct plist_node *node,
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int del, int value)
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{
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unsigned long flags;
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int prev_value, curr_value;
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spin_lock_irqsave(&pm_qos_lock, flags);
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prev_value = pm_qos_get_value(o);
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/* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
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if (value != PM_QOS_DEFAULT_VALUE) {
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/*
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* to change the list, we atomically remove, reinit
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* with new value and add, then see if the extremal
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* changed
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*/
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plist_del(node, &o->requests);
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plist_node_init(node, value);
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plist_add(node, &o->requests);
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} else if (del) {
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plist_del(node, &o->requests);
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} else {
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plist_add(node, &o->requests);
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}
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curr_value = pm_qos_get_value(o);
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pm_qos_set_value(o, curr_value);
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spin_unlock_irqrestore(&pm_qos_lock, flags);
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if (prev_value != curr_value)
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blocking_notifier_call_chain(o->notifiers,
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(unsigned long)curr_value,
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NULL);
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}
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static int register_pm_qos_misc(struct pm_qos_object *qos)
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{
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qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
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qos->pm_qos_power_miscdev.name = qos->name;
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qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
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return misc_register(&qos->pm_qos_power_miscdev);
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}
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static int find_pm_qos_object_by_minor(int minor)
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{
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int pm_qos_class;
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for (pm_qos_class = 0;
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pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
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if (minor ==
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pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
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return pm_qos_class;
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}
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return -1;
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}
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/**
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* pm_qos_request - returns current system wide qos expectation
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* @pm_qos_class: identification of which qos value is requested
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*
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* This function returns the current target value.
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*/
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int pm_qos_request(int pm_qos_class)
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{
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return pm_qos_read_value(pm_qos_array[pm_qos_class]);
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}
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EXPORT_SYMBOL_GPL(pm_qos_request);
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int pm_qos_request_active(struct pm_qos_request_list *req)
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{
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return req->pm_qos_class != 0;
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}
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EXPORT_SYMBOL_GPL(pm_qos_request_active);
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/**
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* pm_qos_add_request - inserts new qos request into the list
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* @dep: pointer to a preallocated handle
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* @pm_qos_class: identifies which list of qos request to use
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* @value: defines the qos request
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*
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* This function inserts a new entry in the pm_qos_class list of requested qos
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* performance characteristics. It recomputes the aggregate QoS expectations
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* for the pm_qos_class of parameters and initializes the pm_qos_request_list
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* handle. Caller needs to save this handle for later use in updates and
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* removal.
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*/
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void pm_qos_add_request(struct pm_qos_request_list *dep,
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int pm_qos_class, s32 value)
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{
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struct pm_qos_object *o = pm_qos_array[pm_qos_class];
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int new_value;
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if (pm_qos_request_active(dep)) {
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WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
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return;
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}
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if (value == PM_QOS_DEFAULT_VALUE)
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new_value = o->default_value;
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else
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new_value = value;
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plist_node_init(&dep->list, new_value);
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dep->pm_qos_class = pm_qos_class;
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update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE);
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}
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EXPORT_SYMBOL_GPL(pm_qos_add_request);
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/**
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* pm_qos_update_request - modifies an existing qos request
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* @pm_qos_req : handle to list element holding a pm_qos request to use
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* @value: defines the qos request
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*
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* Updates an existing qos request for the pm_qos_class of parameters along
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* with updating the target pm_qos_class value.
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*
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* Attempts are made to make this code callable on hot code paths.
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*/
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void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
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s32 new_value)
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{
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s32 temp;
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struct pm_qos_object *o;
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if (!pm_qos_req) /*guard against callers passing in null */
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return;
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if (!pm_qos_request_active(pm_qos_req)) {
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WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
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return;
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}
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o = pm_qos_array[pm_qos_req->pm_qos_class];
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if (new_value == PM_QOS_DEFAULT_VALUE)
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temp = o->default_value;
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else
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temp = new_value;
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if (temp != pm_qos_req->list.prio)
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update_target(o, &pm_qos_req->list, 0, temp);
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}
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EXPORT_SYMBOL_GPL(pm_qos_update_request);
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/**
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* pm_qos_remove_request - modifies an existing qos request
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* @pm_qos_req: handle to request list element
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*
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* Will remove pm qos request from the list of requests and
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* recompute the current target value for the pm_qos_class. Call this
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* on slow code paths.
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*/
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void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
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{
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struct pm_qos_object *o;
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if (pm_qos_req == NULL)
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return;
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/* silent return to keep pcm code cleaner */
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if (!pm_qos_request_active(pm_qos_req)) {
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WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
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return;
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}
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o = pm_qos_array[pm_qos_req->pm_qos_class];
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update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
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memset(pm_qos_req, 0, sizeof(*pm_qos_req));
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}
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EXPORT_SYMBOL_GPL(pm_qos_remove_request);
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/**
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* pm_qos_add_notifier - sets notification entry for changes to target value
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* @pm_qos_class: identifies which qos target changes should be notified.
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* @notifier: notifier block managed by caller.
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*
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* will register the notifier into a notification chain that gets called
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* upon changes to the pm_qos_class target value.
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*/
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int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
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{
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int retval;
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retval = blocking_notifier_chain_register(
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pm_qos_array[pm_qos_class]->notifiers, notifier);
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return retval;
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}
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EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
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/**
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* pm_qos_remove_notifier - deletes notification entry from chain.
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* @pm_qos_class: identifies which qos target changes are notified.
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* @notifier: notifier block to be removed.
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*
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* will remove the notifier from the notification chain that gets called
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* upon changes to the pm_qos_class target value.
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*/
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int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
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{
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int retval;
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retval = blocking_notifier_chain_unregister(
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pm_qos_array[pm_qos_class]->notifiers, notifier);
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return retval;
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}
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EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
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static int pm_qos_power_open(struct inode *inode, struct file *filp)
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{
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long pm_qos_class;
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pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
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if (pm_qos_class >= 0) {
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struct pm_qos_request_list *req = kzalloc(sizeof(*req), GFP_KERNEL);
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if (!req)
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return -ENOMEM;
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pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
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filp->private_data = req;
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if (filp->private_data)
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return 0;
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}
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return -EPERM;
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}
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static int pm_qos_power_release(struct inode *inode, struct file *filp)
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{
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struct pm_qos_request_list *req;
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req = filp->private_data;
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pm_qos_remove_request(req);
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kfree(req);
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return 0;
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}
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static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
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size_t count, loff_t *f_pos)
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{
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s32 value;
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unsigned long flags;
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struct pm_qos_object *o;
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struct pm_qos_request_list *pm_qos_req = filp->private_data;
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if (!pm_qos_req)
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return -EINVAL;
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if (!pm_qos_request_active(pm_qos_req))
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return -EINVAL;
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o = pm_qos_array[pm_qos_req->pm_qos_class];
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spin_lock_irqsave(&pm_qos_lock, flags);
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value = pm_qos_get_value(o);
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spin_unlock_irqrestore(&pm_qos_lock, flags);
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return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
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}
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static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *f_pos)
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{
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s32 value;
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struct pm_qos_request_list *pm_qos_req;
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if (count == sizeof(s32)) {
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if (copy_from_user(&value, buf, sizeof(s32)))
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return -EFAULT;
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} else if (count <= 11) { /* ASCII perhaps? */
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char ascii_value[11];
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unsigned long int ulval;
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int ret;
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if (copy_from_user(ascii_value, buf, count))
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return -EFAULT;
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if (count > 10) {
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if (ascii_value[10] == '\n')
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ascii_value[10] = '\0';
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else
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return -EINVAL;
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} else {
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ascii_value[count] = '\0';
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}
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ret = strict_strtoul(ascii_value, 16, &ulval);
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if (ret) {
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pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
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return -EINVAL;
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}
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value = (s32)lower_32_bits(ulval);
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} else {
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return -EINVAL;
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}
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pm_qos_req = filp->private_data;
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pm_qos_update_request(pm_qos_req, value);
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return count;
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}
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static int __init pm_qos_power_init(void)
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{
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int ret = 0;
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ret = register_pm_qos_misc(&cpu_dma_pm_qos);
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if (ret < 0) {
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printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
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return ret;
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}
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ret = register_pm_qos_misc(&network_lat_pm_qos);
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if (ret < 0) {
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printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
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return ret;
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}
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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);
|