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|
// SPDX-License-Identifier: GPL-2.0-only
/*
* 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/debugfs.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/export.h>
#include <trace/events/power.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
*/
static DEFINE_SPINLOCK(pm_qos_lock);
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,
.no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
.type = PM_QOS_MIN,
.notifiers = &cpu_dma_lat_notifier,
};
/**
* pm_qos_read_value - Return the current effective constraint value.
* @c: List of PM QoS constraint requests.
*/
s32 pm_qos_read_value(struct pm_qos_constraints *c)
{
return c->target_value;
}
static int pm_qos_get_value(struct pm_qos_constraints *c)
{
if (plist_head_empty(&c->list))
return c->no_constraint_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:
WARN(1, "Unknown PM QoS type in %s\n", __func__);
return PM_QOS_DEFAULT_VALUE;
}
}
static void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
{
c->target_value = value;
}
/**
* pm_qos_update_target - Update a list of PM QoS constraint requests.
* @c: List of PM QoS requests.
* @node: Target list entry.
* @action: Action to carry out (add, update or remove).
* @value: New request value for the target list entry.
*
* Update the given list of PM QoS constraint requests, @c, by carrying an
* @action involving the @node list entry and @value on it.
*
* The recognized values of @action are PM_QOS_ADD_REQ (store @value in @node
* and add it to the list), PM_QOS_UPDATE_REQ (remove @node from the list, store
* @value in it and add it to the list again), and PM_QOS_REMOVE_REQ (remove
* @node from the list, ignore @value).
*
* Return: 1 if the aggregate 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)
{
int prev_value, curr_value, new_value;
unsigned long flags;
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, atomically remove, reinit with new value
* and add, then see if the aggregate has changed.
*/
plist_del(node, &c->list);
/* fall through */
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);
trace_pm_qos_update_target(action, prev_value, curr_value);
if (prev_value == curr_value)
return 0;
if (c->notifiers)
blocking_notifier_call_chain(c->notifiers, curr_value, NULL);
return 1;
}
/**
* pm_qos_flags_remove_req - Remove device PM QoS flags request.
* @pqf: Device PM QoS flags set to remove the request from.
* @req: Request to remove from the set.
*/
static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
struct pm_qos_flags_request *req)
{
s32 val = 0;
list_del(&req->node);
list_for_each_entry(req, &pqf->list, node)
val |= req->flags;
pqf->effective_flags = val;
}
/**
* pm_qos_update_flags - Update a set of PM QoS flags.
* @pqf: Set of PM QoS flags to update.
* @req: Request to add to the set, to modify, or to remove from the set.
* @action: Action to take on the set.
* @val: Value of the request to add or modify.
*
* Return: 1 if the aggregate constraint value has changed, 0 otherwise.
*/
bool pm_qos_update_flags(struct pm_qos_flags *pqf,
struct pm_qos_flags_request *req,
enum pm_qos_req_action action, s32 val)
{
unsigned long irqflags;
s32 prev_value, curr_value;
spin_lock_irqsave(&pm_qos_lock, irqflags);
prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
switch (action) {
case PM_QOS_REMOVE_REQ:
pm_qos_flags_remove_req(pqf, req);
break;
case PM_QOS_UPDATE_REQ:
pm_qos_flags_remove_req(pqf, req);
/* fall through */
case PM_QOS_ADD_REQ:
req->flags = val;
INIT_LIST_HEAD(&req->node);
list_add_tail(&req->node, &pqf->list);
pqf->effective_flags |= val;
break;
default:
/* no action */
;
}
curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
spin_unlock_irqrestore(&pm_qos_lock, irqflags);
trace_pm_qos_update_flags(action, prev_value, curr_value);
return prev_value != curr_value;
}
/**
* pm_qos_request - returns current system wide qos expectation
* @pm_qos_class: Ignored.
*
* This function returns the current target value.
*/
int pm_qos_request(int pm_qos_class)
{
return pm_qos_read_value(&cpu_dma_constraints);
}
EXPORT_SYMBOL_GPL(pm_qos_request);
int pm_qos_request_active(struct pm_qos_request *req)
{
return req->qos == &cpu_dma_constraints;
}
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: Ignored.
* @value: defines the qos request
*
* This function inserts a new entry in the PM_QOS_CPU_DMA_LATENCY list of
* requested QoS performance characteristics. It recomputes the aggregate QoS
* expectations for the PM_QOS_CPU_DMA_LATENCY list and initializes the @req
* 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;
}
trace_pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY, value);
req->qos = &cpu_dma_constraints;
pm_qos_update_target(req->qos, &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_CPU_DMA_LATENCY list along
* with updating the target PM_QOS_CPU_DMA_LATENCY 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;
}
trace_pm_qos_update_request(PM_QOS_CPU_DMA_LATENCY, new_value);
if (new_value == req->node.prio)
return;
pm_qos_update_target(req->qos, &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 PM_QOS_CPU_DMA_LATENCY. 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;
}
trace_pm_qos_remove_request(PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);
pm_qos_update_target(req->qos, &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: Ignored.
* @notifier: notifier block managed by caller.
*
* will register the notifier into a notification chain that gets called
* upon changes to the PM_QOS_CPU_DMA_LATENCY target value.
*/
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
return blocking_notifier_chain_register(cpu_dma_constraints.notifiers,
notifier);
}
EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
/**
* pm_qos_remove_notifier - deletes notification entry from chain.
* @pm_qos_class: Ignored.
* @notifier: notifier block to be removed.
*
* will remove the notifier from the notification chain that gets called
* upon changes to the PM_QOS_CPU_DMA_LATENCY target value.
*/
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
{
return blocking_notifier_chain_unregister(cpu_dma_constraints.notifiers,
notifier);
}
EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
/* User space interface to global PM QoS via misc device. */
static int pm_qos_power_open(struct inode *inode, struct file *filp)
{
struct pm_qos_request *req;
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
return -ENOMEM;
pm_qos_add_request(req, PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);
filp->private_data = req;
return 0;
}
static int pm_qos_power_release(struct inode *inode, struct file *filp)
{
struct pm_qos_request *req = filp->private_data;
filp->private_data = NULL;
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)
{
struct pm_qos_request *req = filp->private_data;
unsigned long flags;
s32 value;
if (!req || !pm_qos_request_active(req))
return -EINVAL;
spin_lock_irqsave(&pm_qos_lock, flags);
value = pm_qos_get_value(&cpu_dma_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;
if (count == sizeof(s32)) {
if (copy_from_user(&value, buf, sizeof(s32)))
return -EFAULT;
} else {
int ret;
ret = kstrtos32_from_user(buf, count, 16, &value);
if (ret)
return ret;
}
pm_qos_update_request(filp->private_data, value);
return count;
}
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 struct miscdevice cpu_latency_qos_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "cpu_dma_latency",
.fops = &pm_qos_power_fops,
};
static int __init pm_qos_power_init(void)
{
int ret;
ret = misc_register(&cpu_latency_qos_miscdev);
if (ret < 0)
pr_err("%s: %s setup failed\n", __func__,
cpu_latency_qos_miscdev.name);
return ret;
}
late_initcall(pm_qos_power_init);
/* Definitions related to the frequency QoS below. */
/**
* freq_constraints_init - Initialize frequency QoS constraints.
* @qos: Frequency QoS constraints to initialize.
*/
void freq_constraints_init(struct freq_constraints *qos)
{
struct pm_qos_constraints *c;
c = &qos->min_freq;
plist_head_init(&c->list);
c->target_value = FREQ_QOS_MIN_DEFAULT_VALUE;
c->default_value = FREQ_QOS_MIN_DEFAULT_VALUE;
c->no_constraint_value = FREQ_QOS_MIN_DEFAULT_VALUE;
c->type = PM_QOS_MAX;
c->notifiers = &qos->min_freq_notifiers;
BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
c = &qos->max_freq;
plist_head_init(&c->list);
c->target_value = FREQ_QOS_MAX_DEFAULT_VALUE;
c->default_value = FREQ_QOS_MAX_DEFAULT_VALUE;
c->no_constraint_value = FREQ_QOS_MAX_DEFAULT_VALUE;
c->type = PM_QOS_MIN;
c->notifiers = &qos->max_freq_notifiers;
BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
}
/**
* freq_qos_read_value - Get frequency QoS constraint for a given list.
* @qos: Constraints to evaluate.
* @type: QoS request type.
*/
s32 freq_qos_read_value(struct freq_constraints *qos,
enum freq_qos_req_type type)
{
s32 ret;
switch (type) {
case FREQ_QOS_MIN:
ret = IS_ERR_OR_NULL(qos) ?
FREQ_QOS_MIN_DEFAULT_VALUE :
pm_qos_read_value(&qos->min_freq);
break;
case FREQ_QOS_MAX:
ret = IS_ERR_OR_NULL(qos) ?
FREQ_QOS_MAX_DEFAULT_VALUE :
pm_qos_read_value(&qos->max_freq);
break;
default:
WARN_ON(1);
ret = 0;
}
return ret;
}
/**
* freq_qos_apply - Add/modify/remove frequency QoS request.
* @req: Constraint request to apply.
* @action: Action to perform (add/update/remove).
* @value: Value to assign to the QoS request.
*
* This is only meant to be called from inside pm_qos, not drivers.
*/
int freq_qos_apply(struct freq_qos_request *req,
enum pm_qos_req_action action, s32 value)
{
int ret;
switch(req->type) {
case FREQ_QOS_MIN:
ret = pm_qos_update_target(&req->qos->min_freq, &req->pnode,
action, value);
break;
case FREQ_QOS_MAX:
ret = pm_qos_update_target(&req->qos->max_freq, &req->pnode,
action, value);
break;
default:
ret = -EINVAL;
}
return ret;
}
/**
* freq_qos_add_request - Insert new frequency QoS request into a given list.
* @qos: Constraints to update.
* @req: Preallocated request object.
* @type: Request type.
* @value: Request value.
*
* Insert a new entry into the @qos list of requests, recompute the effective
* QoS constraint value for that list and initialize the @req object. The
* caller needs to save that object for later use in updates and removal.
*
* Return 1 if the effective constraint value has changed, 0 if the effective
* constraint value has not changed, or a negative error code on failures.
*/
int freq_qos_add_request(struct freq_constraints *qos,
struct freq_qos_request *req,
enum freq_qos_req_type type, s32 value)
{
int ret;
if (IS_ERR_OR_NULL(qos) || !req)
return -EINVAL;
if (WARN(freq_qos_request_active(req),
"%s() called for active request\n", __func__))
return -EINVAL;
req->qos = qos;
req->type = type;
ret = freq_qos_apply(req, PM_QOS_ADD_REQ, value);
if (ret < 0) {
req->qos = NULL;
req->type = 0;
}
return ret;
}
EXPORT_SYMBOL_GPL(freq_qos_add_request);
/**
* freq_qos_update_request - Modify existing frequency QoS request.
* @req: Request to modify.
* @new_value: New request value.
*
* Update an existing frequency QoS request along with the effective constraint
* value for the list of requests it belongs to.
*
* Return 1 if the effective constraint value has changed, 0 if the effective
* constraint value has not changed, or a negative error code on failures.
*/
int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
{
if (!req)
return -EINVAL;
if (WARN(!freq_qos_request_active(req),
"%s() called for unknown object\n", __func__))
return -EINVAL;
if (req->pnode.prio == new_value)
return 0;
return freq_qos_apply(req, PM_QOS_UPDATE_REQ, new_value);
}
EXPORT_SYMBOL_GPL(freq_qos_update_request);
/**
* freq_qos_remove_request - Remove frequency QoS request from its list.
* @req: Request to remove.
*
* Remove the given frequency QoS request from the list of constraints it
* belongs to and recompute the effective constraint value for that list.
*
* Return 1 if the effective constraint value has changed, 0 if the effective
* constraint value has not changed, or a negative error code on failures.
*/
int freq_qos_remove_request(struct freq_qos_request *req)
{
int ret;
if (!req)
return -EINVAL;
if (WARN(!freq_qos_request_active(req),
"%s() called for unknown object\n", __func__))
return -EINVAL;
ret = freq_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
req->qos = NULL;
req->type = 0;
return ret;
}
EXPORT_SYMBOL_GPL(freq_qos_remove_request);
/**
* freq_qos_add_notifier - Add frequency QoS change notifier.
* @qos: List of requests to add the notifier to.
* @type: Request type.
* @notifier: Notifier block to add.
*/
int freq_qos_add_notifier(struct freq_constraints *qos,
enum freq_qos_req_type type,
struct notifier_block *notifier)
{
int ret;
if (IS_ERR_OR_NULL(qos) || !notifier)
return -EINVAL;
switch (type) {
case FREQ_QOS_MIN:
ret = blocking_notifier_chain_register(qos->min_freq.notifiers,
notifier);
break;
case FREQ_QOS_MAX:
ret = blocking_notifier_chain_register(qos->max_freq.notifiers,
notifier);
break;
default:
WARN_ON(1);
ret = -EINVAL;
}
return ret;
}
EXPORT_SYMBOL_GPL(freq_qos_add_notifier);
/**
* freq_qos_remove_notifier - Remove frequency QoS change notifier.
* @qos: List of requests to remove the notifier from.
* @type: Request type.
* @notifier: Notifier block to remove.
*/
int freq_qos_remove_notifier(struct freq_constraints *qos,
enum freq_qos_req_type type,
struct notifier_block *notifier)
{
int ret;
if (IS_ERR_OR_NULL(qos) || !notifier)
return -EINVAL;
switch (type) {
case FREQ_QOS_MIN:
ret = blocking_notifier_chain_unregister(qos->min_freq.notifiers,
notifier);
break;
case FREQ_QOS_MAX:
ret = blocking_notifier_chain_unregister(qos->max_freq.notifiers,
notifier);
break;
default:
WARN_ON(1);
ret = -EINVAL;
}
return ret;
}
EXPORT_SYMBOL_GPL(freq_qos_remove_notifier);
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