/*
   * Copyright 2010 ARM Ltd.
   *
   * Perf-events backend for OProfile.
   */
  #include <linux/perf_event.h>

  #include <linux/platform_device.h>

  #include <linux/oprofile.h>
  #include <linux/slab.h>
  
  /*
   * Per performance monitor configuration as set via oprofilefs.
   */
  struct op_counter_config {
  	unsigned long count;
  	unsigned long enabled;
  	unsigned long event;
  	unsigned long unit_mask;
  	unsigned long kernel;
  	unsigned long user;
  	struct perf_event_attr attr;
  };
  
  static int oprofile_perf_enabled;
  static DEFINE_MUTEX(oprofile_perf_mutex);
  
  static struct op_counter_config *counter_config;
  static struct perf_event **perf_events[nr_cpumask_bits];
  static int num_counters;
  
  /*
   * Overflow callback for oprofile.
   */

  static void op_overflow_handler(struct perf_event *event,

  			struct perf_sample_data *data, struct pt_regs *regs)
  {
  	int id;
  	u32 cpu = smp_processor_id();
  
  	for (id = 0; id < num_counters; ++id)
  		if (perf_events[cpu][id] == event)
  			break;
  
  	if (id != num_counters)
  		oprofile_add_sample(regs, id);
  	else
  		pr_warning("oprofile: ignoring spurious overflow "
  				"on cpu %u
  ", cpu);
  }
  
  /*
   * Called by oprofile_perf_setup to create perf attributes to mirror the oprofile
   * settings in counter_config. Attributes are created as `pinned' events and
   * so are permanently scheduled on the PMU.
   */
  static void op_perf_setup(void)
  {
  	int i;
  	u32 size = sizeof(struct perf_event_attr);
  	struct perf_event_attr *attr;
  
  	for (i = 0; i < num_counters; ++i) {
  		attr = &counter_config[i].attr;
  		memset(attr, 0, size);
  		attr->type		= PERF_TYPE_RAW;
  		attr->size		= size;
  		attr->config		= counter_config[i].event;
  		attr->sample_period	= counter_config[i].count;
  		attr->pinned		= 1;
  	}
  }
  
  static int op_create_counter(int cpu, int event)
  {

  	struct perf_event *pevent;

  	if (!counter_config[event].enabled || perf_events[cpu][event])
  		return 0;

  
  	pevent = perf_event_create_kernel_counter(&counter_config[event].attr,

  						  cpu, NULL,

  						  op_overflow_handler, NULL);

  	if (IS_ERR(pevent))
  		return PTR_ERR(pevent);
  
  	if (pevent->state != PERF_EVENT_STATE_ACTIVE) {

  		perf_event_release_kernel(pevent);

  		pr_warning("oprofile: failed to enable event %d "
  				"on CPU %d
  ", event, cpu);

  		return -EBUSY;

  	}

  	perf_events[cpu][event] = pevent;
  
  	return 0;

  }
  
  static void op_destroy_counter(int cpu, int event)
  {
  	struct perf_event *pevent = perf_events[cpu][event];
  
  	if (pevent) {
  		perf_event_release_kernel(pevent);
  		perf_events[cpu][event] = NULL;
  	}
  }
  
  /*
   * Called by oprofile_perf_start to create active perf events based on the
   * perviously configured attributes.
   */
  static int op_perf_start(void)
  {
  	int cpu, event, ret = 0;
  
  	for_each_online_cpu(cpu) {
  		for (event = 0; event < num_counters; ++event) {
  			ret = op_create_counter(cpu, event);
  			if (ret)

  				return ret;

  		}
  	}

  	return ret;
  }
  
  /*
   * Called by oprofile_perf_stop at the end of a profiling run.
   */
  static void op_perf_stop(void)
  {
  	int cpu, event;
  
  	for_each_online_cpu(cpu)
  		for (event = 0; event < num_counters; ++event)
  			op_destroy_counter(cpu, event);
  }
  
  static int oprofile_perf_create_files(struct super_block *sb, struct dentry *root)
  {
  	unsigned int i;
  
  	for (i = 0; i < num_counters; i++) {
  		struct dentry *dir;
  		char buf[4];
  
  		snprintf(buf, sizeof buf, "%d", i);
  		dir = oprofilefs_mkdir(sb, root, buf);
  		oprofilefs_create_ulong(sb, dir, "enabled", &counter_config[i].enabled);
  		oprofilefs_create_ulong(sb, dir, "event", &counter_config[i].event);
  		oprofilefs_create_ulong(sb, dir, "count", &counter_config[i].count);
  		oprofilefs_create_ulong(sb, dir, "unit_mask", &counter_config[i].unit_mask);
  		oprofilefs_create_ulong(sb, dir, "kernel", &counter_config[i].kernel);
  		oprofilefs_create_ulong(sb, dir, "user", &counter_config[i].user);
  	}
  
  	return 0;
  }
  
  static int oprofile_perf_setup(void)
  {

  	raw_spin_lock(&oprofilefs_lock);

  	op_perf_setup();

  	raw_spin_unlock(&oprofilefs_lock);

  	return 0;
  }
  
  static int oprofile_perf_start(void)
  {
  	int ret = -EBUSY;
  
  	mutex_lock(&oprofile_perf_mutex);
  	if (!oprofile_perf_enabled) {
  		ret = 0;
  		op_perf_start();
  		oprofile_perf_enabled = 1;
  	}
  	mutex_unlock(&oprofile_perf_mutex);
  	return ret;
  }
  
  static void oprofile_perf_stop(void)
  {
  	mutex_lock(&oprofile_perf_mutex);
  	if (oprofile_perf_enabled)
  		op_perf_stop();
  	oprofile_perf_enabled = 0;
  	mutex_unlock(&oprofile_perf_mutex);
  }
  
  #ifdef CONFIG_PM

  static int oprofile_perf_suspend(struct platform_device *dev, pm_message_t state)
  {
  	mutex_lock(&oprofile_perf_mutex);
  	if (oprofile_perf_enabled)
  		op_perf_stop();
  	mutex_unlock(&oprofile_perf_mutex);
  	return 0;
  }
  
  static int oprofile_perf_resume(struct platform_device *dev)
  {
  	mutex_lock(&oprofile_perf_mutex);
  	if (oprofile_perf_enabled && op_perf_start())
  		oprofile_perf_enabled = 0;
  	mutex_unlock(&oprofile_perf_mutex);
  	return 0;
  }
  
  static struct platform_driver oprofile_driver = {
  	.driver		= {
  		.name		= "oprofile-perf",
  	},
  	.resume		= oprofile_perf_resume,
  	.suspend	= oprofile_perf_suspend,
  };
  
  static struct platform_device *oprofile_pdev;
  
  static int __init init_driverfs(void)
  {
  	int ret;
  
  	ret = platform_driver_register(&oprofile_driver);
  	if (ret)

  		return ret;

  
  	oprofile_pdev =	platform_device_register_simple(
  				oprofile_driver.driver.name, 0, NULL, 0);
  	if (IS_ERR(oprofile_pdev)) {
  		ret = PTR_ERR(oprofile_pdev);
  		platform_driver_unregister(&oprofile_driver);
  	}

  	return ret;
  }

  static void exit_driverfs(void)

  {
  	platform_device_unregister(oprofile_pdev);
  	platform_driver_unregister(&oprofile_driver);
  }

  #else

  
  static inline int  init_driverfs(void) { return 0; }
  static inline void exit_driverfs(void) { }

  #endif /* CONFIG_PM */

  void oprofile_perf_exit(void)
  {
  	int cpu, id;
  	struct perf_event *event;
  
  	for_each_possible_cpu(cpu) {
  		for (id = 0; id < num_counters; ++id) {
  			event = perf_events[cpu][id];
  			if (event)
  				perf_event_release_kernel(event);
  		}
  
  		kfree(perf_events[cpu]);
  	}
  
  	kfree(counter_config);
  	exit_driverfs();
  }

  int __init oprofile_perf_init(struct oprofile_operations *ops)
  {
  	int cpu, ret = 0;

  	ret = init_driverfs();
  	if (ret)
  		return ret;

  	memset(&perf_events, 0, sizeof(perf_events));
  
  	num_counters = perf_num_counters();
  	if (num_counters <= 0) {
  		pr_info("oprofile: no performance counters
  ");
  		ret = -ENODEV;
  		goto out;
  	}
  
  	counter_config = kcalloc(num_counters,
  			sizeof(struct op_counter_config), GFP_KERNEL);
  
  	if (!counter_config) {
  		pr_info("oprofile: failed to allocate %d "
  				"counters
  ", num_counters);
  		ret = -ENOMEM;

  		num_counters = 0;

  		goto out;
  	}

  	for_each_possible_cpu(cpu) {
  		perf_events[cpu] = kcalloc(num_counters,
  				sizeof(struct perf_event *), GFP_KERNEL);
  		if (!perf_events[cpu]) {
  			pr_info("oprofile: failed to allocate %d perf events "
  					"for cpu %d
  ", num_counters, cpu);
  			ret = -ENOMEM;
  			goto out;
  		}
  	}
  
  	ops->create_files	= oprofile_perf_create_files;
  	ops->setup		= oprofile_perf_setup;
  	ops->start		= oprofile_perf_start;
  	ops->stop		= oprofile_perf_stop;
  	ops->shutdown		= oprofile_perf_stop;
  	ops->cpu_type		= op_name_from_perf_id();
  
  	if (!ops->cpu_type)
  		ret = -ENODEV;
  	else
  		pr_info("oprofile: using %s
  ", ops->cpu_type);
  
  out:

  	if (ret)
  		oprofile_perf_exit();

  
  	return ret;
  }