diff options
Diffstat (limited to 'kernel/power/qos.c')
| -rw-r--r-- | kernel/power/qos.c | 673 |
1 files changed, 673 insertions, 0 deletions
diff --git a/kernel/power/qos.c b/kernel/power/qos.c new file mode 100644 index 000000000..ec7e1e859 --- /dev/null +++ b/kernel/power/qos.c @@ -0,0 +1,673 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Power Management Quality of Service (PM QoS) support base. + * + * Copyright (C) 2020 Intel Corporation + * + * Authors: + * Mark Gross <mgross@linux.intel.com> + * Rafael J. Wysocki <rafael.j.wysocki@intel.com> + * + * Provided here is an interface for specifying PM QoS dependencies. It allows + * entities depending on QoS constraints to register their requests which are + * aggregated as appropriate to produce effective constraints (target values) + * that can be monitored by entities needing to respect them, either by polling + * or through a built-in notification mechanism. + * + * In addition to the basic functionality, more specific interfaces for managing + * global CPU latency QoS requests and frequency QoS requests are provided. + */ + +/*#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); + +/** + * 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 READ_ONCE(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) +{ + WRITE_ONCE(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); + fallthrough; + 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); + fallthrough; + 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; +} + +#ifdef CONFIG_CPU_IDLE +/* Definitions related to the CPU latency QoS. */ + +static struct pm_qos_constraints cpu_latency_constraints = { + .list = PLIST_HEAD_INIT(cpu_latency_constraints.list), + .target_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE, + .default_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE, + .no_constraint_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE, + .type = PM_QOS_MIN, +}; + +/** + * cpu_latency_qos_limit - Return current system-wide CPU latency QoS limit. + */ +s32 cpu_latency_qos_limit(void) +{ + return pm_qos_read_value(&cpu_latency_constraints); +} + +/** + * cpu_latency_qos_request_active - Check the given PM QoS request. + * @req: PM QoS request to check. + * + * Return: 'true' if @req has been added to the CPU latency QoS list, 'false' + * otherwise. + */ +bool cpu_latency_qos_request_active(struct pm_qos_request *req) +{ + return req->qos == &cpu_latency_constraints; +} +EXPORT_SYMBOL_GPL(cpu_latency_qos_request_active); + +static void cpu_latency_qos_apply(struct pm_qos_request *req, + enum pm_qos_req_action action, s32 value) +{ + int ret = pm_qos_update_target(req->qos, &req->node, action, value); + if (ret > 0) + wake_up_all_idle_cpus(); +} + +/** + * cpu_latency_qos_add_request - Add new CPU latency QoS request. + * @req: Pointer to a preallocated handle. + * @value: Requested constraint value. + * + * Use @value to initialize the request handle pointed to by @req, insert it as + * a new entry to the CPU latency QoS list and recompute the effective QoS + * constraint for that list. + * + * Callers need to save the handle for later use in updates and removal of the + * QoS request represented by it. + */ +void cpu_latency_qos_add_request(struct pm_qos_request *req, s32 value) +{ + if (!req) + return; + + if (cpu_latency_qos_request_active(req)) { + WARN(1, KERN_ERR "%s called for already added request\n", __func__); + return; + } + + trace_pm_qos_add_request(value); + + req->qos = &cpu_latency_constraints; + cpu_latency_qos_apply(req, PM_QOS_ADD_REQ, value); +} +EXPORT_SYMBOL_GPL(cpu_latency_qos_add_request); + +/** + * cpu_latency_qos_update_request - Modify existing CPU latency QoS request. + * @req : QoS request to update. + * @new_value: New requested constraint value. + * + * Use @new_value to update the QoS request represented by @req in the CPU + * latency QoS list along with updating the effective constraint value for that + * list. + */ +void cpu_latency_qos_update_request(struct pm_qos_request *req, s32 new_value) +{ + if (!req) + return; + + if (!cpu_latency_qos_request_active(req)) { + WARN(1, KERN_ERR "%s called for unknown object\n", __func__); + return; + } + + trace_pm_qos_update_request(new_value); + + if (new_value == req->node.prio) + return; + + cpu_latency_qos_apply(req, PM_QOS_UPDATE_REQ, new_value); +} +EXPORT_SYMBOL_GPL(cpu_latency_qos_update_request); + +/** + * cpu_latency_qos_remove_request - Remove existing CPU latency QoS request. + * @req: QoS request to remove. + * + * Remove the CPU latency QoS request represented by @req from the CPU latency + * QoS list along with updating the effective constraint value for that list. + */ +void cpu_latency_qos_remove_request(struct pm_qos_request *req) +{ + if (!req) + return; + + if (!cpu_latency_qos_request_active(req)) { + WARN(1, KERN_ERR "%s called for unknown object\n", __func__); + return; + } + + trace_pm_qos_remove_request(PM_QOS_DEFAULT_VALUE); + + cpu_latency_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); + memset(req, 0, sizeof(*req)); +} +EXPORT_SYMBOL_GPL(cpu_latency_qos_remove_request); + +/* User space interface to the CPU latency QoS via misc device. */ + +static int cpu_latency_qos_open(struct inode *inode, struct file *filp) +{ + struct pm_qos_request *req; + + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + return -ENOMEM; + + cpu_latency_qos_add_request(req, PM_QOS_DEFAULT_VALUE); + filp->private_data = req; + + return 0; +} + +static int cpu_latency_qos_release(struct inode *inode, struct file *filp) +{ + struct pm_qos_request *req = filp->private_data; + + filp->private_data = NULL; + + cpu_latency_qos_remove_request(req); + kfree(req); + + return 0; +} + +static ssize_t cpu_latency_qos_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 || !cpu_latency_qos_request_active(req)) + return -EINVAL; + + spin_lock_irqsave(&pm_qos_lock, flags); + value = pm_qos_get_value(&cpu_latency_constraints); + spin_unlock_irqrestore(&pm_qos_lock, flags); + + return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32)); +} + +static ssize_t cpu_latency_qos_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; + } + + cpu_latency_qos_update_request(filp->private_data, value); + + return count; +} + +static const struct file_operations cpu_latency_qos_fops = { + .write = cpu_latency_qos_write, + .read = cpu_latency_qos_read, + .open = cpu_latency_qos_open, + .release = cpu_latency_qos_release, + .llseek = noop_llseek, +}; + +static struct miscdevice cpu_latency_qos_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "cpu_dma_latency", + .fops = &cpu_latency_qos_fops, +}; + +static int __init cpu_latency_qos_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(cpu_latency_qos_init); +#endif /* CONFIG_CPU_IDLE */ + +/* 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); |