/*
* 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_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 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
*/
enum pm_qos_type {
PM_QOS_MAX, /* return the largest value */
PM_QOS_MIN /* return the smallest value */
};
struct pm_qos_object {
struct plist_head requests;
struct blocking_notifier_head *notifiers;
struct miscdevice pm_qos_power_miscdev;
char *name;
s32 default_value;
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 = {
.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,
.type = PM_QOS_MIN,
};
static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
static struct pm_qos_object network_lat_pm_qos = {
.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,
.type = PM_QOS_MIN
};
static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
static struct pm_qos_object network_throughput_pm_qos = {
.requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
.notifiers = &network_throughput_notifier,
.name = "network_throughput",
.default_value = 0,
.type = PM_QOS_MAX,
};
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 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,
.llseek = noop_llseek,
};
/* unlocked internal variant */
static inline int pm_qos_get_value(struct pm_qos_object *o)
{
if (plist_head_empty(&o->requests))
return o->default_value;
switch (o->type) {
case PM_QOS_MIN:
return plist_last(&o->requests)->prio;
case PM_QOS_MAX:
return plist_first(&o->requests)->prio;
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)
{
unsigned long flags;
int prev_value, curr_value;
spin_lock_irqsave(&pm_qos_lock, flags);
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 (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)
{
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_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_request(int pm_qos_class)
{
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_request_active);
/**
* 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 and initializes the pm_qos_request_list
* handle. Caller needs to save this handle for later use in updates and
* removal.
*/
void pm_qos_add_request(struct pm_qos_request_list *dep,
int pm_qos_class, s32 value)
{
struct pm_qos_object *o = pm_qos_array[pm_qos_class];
int new_value;
if (pm_qos_request_active(dep)) {
WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
return;
}
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_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 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_list *pm_qos_req,
s32 new_value)
{
s32 temp;
struct pm_qos_object *o;
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;
}
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_request);
/**
* pm_qos_remove_request - modifies an existing qos request
* @pm_qos_req: handle to request list element
*
* 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_request(struct pm_qos_request_list *pm_qos_req)
{
struct pm_qos_object *o;
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;
}
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_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]->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]->notifiers, notifier);
return retval;
}
EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
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_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;
}
return -EPERM;
}
static int pm_qos_power_release(struct inode *inode, struct file *filp)
{
struct pm_qos_request_list *req;
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,
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 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);
