PM QoS: Move and rename the implementation files

The PM QoS implementation files are better named
kernel/power/qos.c and include/linux/pm_qos.h.

The PM QoS support is compiled under the CONFIG_PM option.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Acked-by: markgross <markgross@thegnar.org>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 482 insertions, 1 deletions

diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index c5ebc6a90643..ad6bdd8b401a 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -1,7 +1,7 @@
 
 ccflags-$(CONFIG_PM_DEBUG)      := -DDEBUG
 
-obj-$(CONFIG_PM)                += main.o
+obj-$(CONFIG_PM)                += main.o qos.o
 obj-$(CONFIG_PM_SLEEP)          += console.o
 obj-$(CONFIG_FREEZER)           += process.o
 obj-$(CONFIG_SUSPEND)           += suspend.o
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
new file mode 100644
index 000000000000..61b47384329e
--- /dev/null
+++ b/kernel/power/qos.c
@@ -0,0 +1,481 @@
+/*
+ * 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>
+
+/*
+ * locking rule: all changes to requests 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
+ */
+enum pm_qos_type {
+        PM_QOS_MAX,             /* return the largest value */
+        PM_QOS_MIN              /* return the smallest value */
+};
+
+/*
+ * Note: The lockless read path depends on the CPU accessing
+ * target_value atomically.  Atomic access is only guaranteed on all CPU
+ * types linux supports for 32 bit quantites
+ */
+struct pm_qos_object {
+        struct plist_head requests;
+        struct blocking_notifier_head *notifiers;
+        struct miscdevice pm_qos_power_miscdev;
+        char *name;
+        s32 target_value;       /* Do not change to 64 bit */
+        s32 default_value;
+        enum pm_qos_type type;
+};
+
+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_object cpu_dma_pm_qos = {
+        .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests),
+        .notifiers = &cpu_dma_lat_notifier,
+        .name = "cpu_dma_latency",
+        .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
+        .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
+        .type = PM_QOS_MIN,
+};
+
+static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
+static struct pm_qos_object network_lat_pm_qos = {
+        .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests),
+        .notifiers = &network_lat_notifier,
+        .name = "network_latency",
+        .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
+        .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
+        .type = PM_QOS_MIN
+};
+
+
+static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
+static struct pm_qos_object network_throughput_pm_qos = {
+        .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests),
+        .notifiers = &network_throughput_notifier,
+        .name = "network_throughput",
+        .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
+        .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
+        .type = PM_QOS_MAX,
+};
+
+
+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_object *o)
+{
+        if (plist_head_empty(&o->requests))
+                return o->default_value;
+
+        switch (o->type) {
+        case PM_QOS_MIN:
+                return plist_first(&o->requests)->prio;
+
+        case PM_QOS_MAX:
+                return plist_last(&o->requests)->prio;
+
+        default:
+                /* runtime check for not using enum */
+                BUG();
+        }
+}
+
+static inline s32 pm_qos_read_value(struct pm_qos_object *o)
+{
+        return o->target_value;
+}
+
+static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value)
+{
+        o->target_value = value;
+}
+
+static void update_target(struct pm_qos_object *o, struct plist_node *node,
+                          int del, int value)
+{
+        unsigned long flags;
+        int prev_value, curr_value;
+
+        spin_lock_irqsave(&pm_qos_lock, flags);
+        prev_value = pm_qos_get_value(o);
+        /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
+        if (value != PM_QOS_DEFAULT_VALUE) {
+                /*
+                 * to change the list, we atomically remove, reinit
+                 * with new value and add, then see if the extremal
+                 * changed
+                 */
+                plist_del(node, &o->requests);
+                plist_node_init(node, value);
+                plist_add(node, &o->requests);
+        } else if (del) {
+                plist_del(node, &o->requests);
+        } else {
+                plist_add(node, &o->requests);
+        }
+        curr_value = pm_qos_get_value(o);
+        pm_qos_set_value(o, curr_value);
+        spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+        if (prev_value != curr_value)
+                blocking_notifier_call_chain(o->notifiers,
+                                             (unsigned long)curr_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_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]);
+}
+EXPORT_SYMBOL_GPL(pm_qos_request);
+
+int pm_qos_request_active(struct pm_qos_request_list *req)
+{
+        return req->pm_qos_class != 0;
+}
+EXPORT_SYMBOL_GPL(pm_qos_request_active);
+
+/**
+ * pm_qos_add_request - inserts new qos request into the list
+ * @dep: 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_list
+ * handle.  Caller needs to save this handle for later use in updates and
+ * removal.
+ */
+
+void pm_qos_add_request(struct pm_qos_request_list *dep,
+                        int pm_qos_class, s32 value)
+{
+        struct pm_qos_object *o =  pm_qos_array[pm_qos_class];
+        int new_value;
+
+        if (pm_qos_request_active(dep)) {
+                WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
+                return;
+        }
+        if (value == PM_QOS_DEFAULT_VALUE)
+                new_value = o->default_value;
+        else
+                new_value = value;
+        plist_node_init(&dep->list, new_value);
+        dep->pm_qos_class = pm_qos_class;
+        update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE);
+}
+EXPORT_SYMBOL_GPL(pm_qos_add_request);
+
+/**
+ * pm_qos_update_request - modifies an existing qos request
+ * @pm_qos_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_list *pm_qos_req,
+                           s32 new_value)
+{
+        s32 temp;
+        struct pm_qos_object *o;
+
+        if (!pm_qos_req) /*guard against callers passing in null */
+                return;
+
+        if (!pm_qos_request_active(pm_qos_req)) {
+                WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
+                return;
+        }
+
+        o = pm_qos_array[pm_qos_req->pm_qos_class];
+
+        if (new_value == PM_QOS_DEFAULT_VALUE)
+                temp = o->default_value;
+        else
+                temp = new_value;
+
+        if (temp != pm_qos_req->list.prio)
+                update_target(o, &pm_qos_req->list, 0, temp);
+}
+EXPORT_SYMBOL_GPL(pm_qos_update_request);
+
+/**
+ * pm_qos_remove_request - modifies an existing qos request
+ * @pm_qos_req: handle to request list element
+ *
+ * Will remove pm qos request from the list of requests 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_list *pm_qos_req)
+{
+        struct pm_qos_object *o;
+
+        if (pm_qos_req == NULL)
+                return;
+                /* silent return to keep pcm code cleaner */
+
+        if (!pm_qos_request_active(pm_qos_req)) {
+                WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
+                return;
+        }
+
+        o = pm_qos_array[pm_qos_req->pm_qos_class];
+        update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
+        memset(pm_qos_req, 0, sizeof(*pm_qos_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]->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);
+
+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_list *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;
+
+                if (filp->private_data)
+                        return 0;
+        }
+        return -EPERM;
+}
+
+static int pm_qos_power_release(struct inode *inode, struct file *filp)
+{
+        struct pm_qos_request_list *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_object *o;
+        struct pm_qos_request_list *pm_qos_req = filp->private_data;
+
+        if (!pm_qos_req)
+                return -EINVAL;
+        if (!pm_qos_request_active(pm_qos_req))
+                return -EINVAL;
+
+        o = pm_qos_array[pm_qos_req->pm_qos_class];
+        spin_lock_irqsave(&pm_qos_lock, flags);
+        value = pm_qos_get_value(o);
+        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_list *pm_qos_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;
+        }
+
+        pm_qos_req = filp->private_data;
+        pm_qos_update_request(pm_qos_req, value);
+
+        return count;
+}
+
+
+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);