/*
* 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>
#include <linux/export.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,
.name = "cpu_dma_latency",
};
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_work_fn - the timeout handler of pm_qos_update_request_timeout
* @work: work struct for the delayed work (timeout)
*
* This cancels the timeout request by falling back to the default at timeout.
*/
static void pm_qos_work_fn(struct work_struct *work)
{
struct pm_qos_request *req = container_of(to_delayed_work(work),
struct pm_qos_request,
work);
pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
}
/**
* 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;
INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
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 (delayed_work_pending(&req->work))
cancel_delayed_work_sync(&req->work);
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_update_request_timeout - modifies an existing qos request temporarily.
* @req : handle to list element holding a pm_qos request to use
* @new_value: defines the temporal qos request
* @timeout_us: the effective duration of this qos request in usecs.
*
* After timeout_us, this qos request is cancelled automatically.
*/
void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
unsigned long timeout_us)
{
if (!req)
return;
if (WARN(!pm_qos_request_active(req),
"%s called for unknown object.", __func__))
return;
if (delayed_work_pending(&req->work))
cancel_delayed_work_sync(&req->work);
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);
schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
}
/**
* 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;
}
if (delayed_work_pending(&req->work))
cancel_delayed_work_sync(&req->work);
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;
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;
int i;
BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
for (i = 1; i < PM_QOS_NUM_CLASSES; i++) {
ret = register_pm_qos_misc(pm_qos_array[i]);
if (ret < 0) {
printk(KERN_ERR "pm_qos_param: %s setup failed\n",
pm_qos_array[i]->name);
return ret;
}
}
return ret;
}
late_initcall(pm_qos_power_init);
