// 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 */ 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, .no_constraint_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 struct pm_qos_object *pm_qos_array[] = { &null_pm_qos, &cpu_dma_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) { struct plist_node *node; int total_value = 0; 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; case PM_QOS_SUM: plist_for_each(node, &c->list) total_value += node->prio; return total_value; default: /* runtime check for not using enum */ BUG(); return PM_QOS_DEFAULT_VALUE; } } 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; } static int pm_qos_debug_show(struct seq_file *s, void *unused) { struct pm_qos_object *qos = (struct pm_qos_object *)s->private; struct pm_qos_constraints *c; struct pm_qos_request *req; char *type; unsigned long flags; int tot_reqs = 0; int active_reqs = 0; if (IS_ERR_OR_NULL(qos)) { pr_err("%s: bad qos param!\n", __func__); return -EINVAL; } c = qos->constraints; if (IS_ERR_OR_NULL(c)) { pr_err("%s: Bad constraints on qos?\n", __func__); return -EINVAL; } /* Lock to ensure we have a snapshot */ spin_lock_irqsave(&pm_qos_lock, flags); if (plist_head_empty(&c->list)) { seq_puts(s, "Empty!\n"); goto out; } switch (c->type) { case PM_QOS_MIN: type = "Minimum"; break; case PM_QOS_MAX: type = "Maximum"; break; case PM_QOS_SUM: type = "Sum"; break; default: type = "Unknown"; } plist_for_each_entry(req, &c->list, node) { char *state = "Default"; if ((req->node).prio != c->default_value) { active_reqs++; state = "Active"; } tot_reqs++; seq_printf(s, "%d: %d: %s\n", tot_reqs, (req->node).prio, state); } seq_printf(s, "Type=%s, Value=%d, Requests: active=%d / total=%d\n", type, pm_qos_get_value(c), active_reqs, tot_reqs); out: spin_unlock_irqrestore(&pm_qos_lock, flags); return 0; } DEFINE_SHOW_ATTRIBUTE(pm_qos_debug); /** * 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; int ret; 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); /* 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) { ret = 1; if (c->notifiers) blocking_notifier_call_chain(c->notifiers, (unsigned long)curr_value, NULL); } else { ret = 0; } return ret; } /** * 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 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. * * Update the given set of PM QoS flags and call notifiers if the aggregate * value has changed. Returns 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: 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); static void __pm_qos_update_request(struct pm_qos_request *req, s32 new_value) { trace_pm_qos_update_request(req->pm_qos_class, new_value); 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); } /** * 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); trace_pm_qos_add_request(pm_qos_class, value); 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; } cancel_delayed_work_sync(&req->work); __pm_qos_update_request(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; cancel_delayed_work_sync(&req->work); trace_pm_qos_update_request_timeout(req->pm_qos_class, new_value, timeout_us); 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; } cancel_delayed_work_sync(&req->work); trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE); 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, struct dentry *d) { 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; debugfs_create_file(qos->name, S_IRUGO, d, (void *)qos, &pm_qos_debug_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 = PM_QOS_CPU_DMA_LATENCY; 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 >= PM_QOS_CPU_DMA_LATENCY) { 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 { int ret; ret = kstrtos32_from_user(buf, count, 16, &value); if (ret) return ret; } 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; struct dentry *d; BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES); d = debugfs_create_dir("pm_qos", NULL); for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) { ret = register_pm_qos_misc(pm_qos_array[i], d); if (ret < 0) { pr_err("%s: %s setup failed\n", __func__, pm_qos_array[i]->name); return ret; } } 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);