diff options
Diffstat (limited to 'kernel/power/qos.c')
| -rw-r--r-- | kernel/power/qos.c | 714 |
1 files changed, 714 insertions, 0 deletions
diff --git a/kernel/power/qos.c b/kernel/power/qos.c new file mode 100644 index 000000000..86d72ffb8 --- /dev/null +++ b/kernel/power/qos.c @@ -0,0 +1,714 @@ +/* + * 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 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, + .no_constraint_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, + .no_constraint_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 BLOCKING_NOTIFIER_HEAD(memory_bandwidth_notifier); +static struct pm_qos_constraints memory_bw_constraints = { + .list = PLIST_HEAD_INIT(memory_bw_constraints.list), + .target_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE, + .default_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE, + .no_constraint_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE, + .type = PM_QOS_SUM, + .notifiers = &memory_bandwidth_notifier, +}; +static struct pm_qos_object memory_bandwidth_pm_qos = { + .constraints = &memory_bw_constraints, + .name = "memory_bandwidth", +}; + + +static struct pm_qos_object *pm_qos_array[] = { + &null_pm_qos, + &cpu_dma_pm_qos, + &network_lat_pm_qos, + &network_throughput_pm_qos, + &memory_bandwidth_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_dbg_show_requests(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; +} + +static int pm_qos_dbg_open(struct inode *inode, struct file *file) +{ + return single_open(file, pm_qos_dbg_show_requests, + inode->i_private); +} + +static const struct file_operations pm_qos_debug_fops = { + .open = pm_qos_dbg_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +/** + * 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; + + if (d) { + (void)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); + if (IS_ERR_OR_NULL(d)) + d = 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); |