/*
   * 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>

  #include <linux/export.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,

  	.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,

  	.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,

  	.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 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_constraints *c)

  {

  	if (plist_head_empty(&c->list))
  		return c->default_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:
  		/* runtime check for not using enum */
  		BUG();
  	}
  }

  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;

  }

  /**
   * 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;

  
  	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);
  	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);

  	if (prev_value != curr_value) {
  		blocking_notifier_call_chain(c->notifiers,

  					     (unsigned long)curr_value,
  					     NULL);

  		return 1;
  	} else {
  		return 0;
  	}

  }

  /**

   * 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);

  /**

   * 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
  ");
  		return;
  	}

  	req->pm_qos_class = pm_qos_class;

  	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
  ");
  		return;
  	}

  	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);

  }

  EXPORT_SYMBOL_GPL(pm_qos_update_request);

  
  /**

   * 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
  ");
  		return;
  	}

  	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)
  {
  	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;
  }

  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 *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 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] == '
  ')
  				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
  ", ascii_value, ulval, ret);

  			return -EINVAL;

  		}
  		value = (s32)lower_32_bits(ulval);
  	} else {

  		return -EINVAL;

  	}

  	req = filp->private_data;
  	pm_qos_update_request(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
  ");
  		return ret;
  	}
  	ret = register_pm_qos_misc(&network_lat_pm_qos);
  	if (ret < 0) {
  		printk(KERN_ERR "pm_qos_param: network_latency setup failed
  ");
  		return ret;
  	}
  	ret = register_pm_qos_misc(&network_throughput_pm_qos);
  	if (ret < 0)
  		printk(KERN_ERR
  			"pm_qos_param: network_throughput setup failed
  ");
  
  	return ret;
  }
  
  late_initcall(pm_qos_power_init);