/* * 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 * 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 requirements, notifiers * * User mode requirements 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 * pointer or exits the pm_qos_object will get an opportunity to clean up. * * Mark Gross <mgross@linux.intel.com> */ #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 requirements 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; }; 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 blocking_notifier_head *notifiers; struct miscdevice pm_qos_power_miscdev; char *name; s32 default_value; atomic_t target_value; s32 (*comparitor)(s32, s32); }; 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)}, .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 }; 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)}, .notifiers = &network_lat_notifier, .name = "network_latency", .default_value = 2000 * USEC_PER_SEC, .target_value = ATOMIC_INIT(2000 * USEC_PER_SEC), .comparitor = min_compare }; 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)}, .notifiers = &network_throughput_notifier, .name = "network_throughput", .default_value = 0, .target_value = ATOMIC_INIT(0), .comparitor = max_compare }; static struct pm_qos_object *pm_qos_array[] = { &null_pm_qos, &cpu_dma_pm_qos, &network_lat_pm_qos, &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 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, }; /* static helper functions */ static s32 max_compare(s32 v1, s32 v2) { return max(v1, v2); } static s32 min_compare(s32 v1, s32 v2) { return min(v1, v2); } static void update_target(int target) { s32 extreme_value; struct requirement_list *node; unsigned long flags; int call_notifier = 0; 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)); } spin_unlock_irqrestore(&pm_qos_lock, flags); if (call_notifier) blocking_notifier_call_chain(pm_qos_array[target]->notifiers, (unsigned long) extreme_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_requirement - 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) { return atomic_read(&pm_qos_array[pm_qos_class]->target_value); } EXPORT_SYMBOL_GPL(pm_qos_requirement); /** * 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 * @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. */ int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value) { struct requirement_list *dep; unsigned long flags; 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; } cleanup: kfree(dep); return -ENOMEM; } EXPORT_SYMBOL_GPL(pm_qos_add_requirement); /** * pm_qos_update_requirement - modifies an existing qos request * @pm_qos_class: identifies which list of qos request to us * @name: identifies the request * @value: defines the qos request * * Updates an existing qos requirement 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. */ int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value) { unsigned long flags; struct requirement_list *node; int pending_update = 0; 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; } } spin_unlock_irqrestore(&pm_qos_lock, flags); if (pending_update) update_target(pm_qos_class); return 0; } EXPORT_SYMBOL_GPL(pm_qos_update_requirement); /** * pm_qos_remove_requirement - modifies an existing qos request * @pm_qos_class: identifies which list of qos request to us * @name: identifies the request * * Will remove named qos request from pm_qos_class list of parameters and * recompute the current target value for the pm_qos_class. */ void pm_qos_remove_requirement(int pm_qos_class, char *name) { unsigned long flags; struct requirement_list *node; int pending_update = 0; 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; } } spin_unlock_irqrestore(&pm_qos_lock, flags); if (pending_update) update_target(pm_qos_class); } EXPORT_SYMBOL_GPL(pm_qos_remove_requirement); /** * 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); #define PID_NAME_LEN 32 static int pm_qos_power_open(struct inode *inode, struct file *filp) { int ret; long pm_qos_class; char name[PID_NAME_LEN]; pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); if (pm_qos_class >= 0) { filp->private_data = (void *)pm_qos_class; snprintf(name, PID_NAME_LEN, "process_%d", current->pid); ret = pm_qos_add_requirement(pm_qos_class, name, PM_QOS_DEFAULT_VALUE); if (ret >= 0) return 0; } return -EPERM; } static int pm_qos_power_release(struct inode *inode, struct file *filp) { int pm_qos_class; char name[PID_NAME_LEN]; pm_qos_class = (long)filp->private_data; snprintf(name, PID_NAME_LEN, "process_%d", current->pid); pm_qos_remove_requirement(pm_qos_class, name); 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 pm_qos_class; char name[PID_NAME_LEN]; pm_qos_class = (long)filp->private_data; if (count != sizeof(s32)) return -EINVAL; if (copy_from_user(&value, buf, sizeof(s32))) return -EFAULT; snprintf(name, PID_NAME_LEN, "process_%d", current->pid); pm_qos_update_requirement(pm_qos_class, name, value); return sizeof(s32); } 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);