/* Copyright (c) 2012, Code Aurora Forum. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/proc_fs.h>

#include "pm.h"

struct msm_pm_time_stats {
	const char *name;
	int64_t first_bucket_time;
	int bucket[CONFIG_MSM_IDLE_STATS_BUCKET_COUNT];
	int64_t min_time[CONFIG_MSM_IDLE_STATS_BUCKET_COUNT];
	int64_t max_time[CONFIG_MSM_IDLE_STATS_BUCKET_COUNT];
	int count;
	int64_t total_time;
	bool enabled;
};

struct msm_pm_cpu_time_stats {
	struct msm_pm_time_stats stats[MSM_PM_STAT_COUNT];
};

static DEFINE_SPINLOCK(msm_pm_stats_lock);
static DEFINE_PER_CPU_SHARED_ALIGNED(
	struct msm_pm_cpu_time_stats, msm_pm_stats);

/*
 * Add the given time data to the statistics collection.
 */
void msm_pm_add_stat(enum msm_pm_time_stats_id id, int64_t t)
{
	unsigned long flags;
	struct msm_pm_time_stats *stats;
	int64_t bt;
	int i;

	spin_lock_irqsave(&msm_pm_stats_lock, flags);
	stats = __get_cpu_var(msm_pm_stats).stats;

	if (!stats[id].enabled)
		goto add_bail;

	stats[id].total_time += t;
	stats[id].count++;

	bt = t;
	do_div(bt, stats[id].first_bucket_time);

	if (bt < 1ULL << (CONFIG_MSM_IDLE_STATS_BUCKET_SHIFT *
				(CONFIG_MSM_IDLE_STATS_BUCKET_COUNT - 1)))
		i = DIV_ROUND_UP(fls((uint32_t)bt),
					CONFIG_MSM_IDLE_STATS_BUCKET_SHIFT);
	else
		i = CONFIG_MSM_IDLE_STATS_BUCKET_COUNT - 1;

	if (i >= CONFIG_MSM_IDLE_STATS_BUCKET_COUNT)
		i = CONFIG_MSM_IDLE_STATS_BUCKET_COUNT - 1;

	stats[id].bucket[i]++;

	if (t < stats[id].min_time[i] || !stats[id].max_time[i])
		stats[id].min_time[i] = t;
	if (t > stats[id].max_time[i])
		stats[id].max_time[i] = t;

add_bail:
	spin_unlock_irqrestore(&msm_pm_stats_lock, flags);
}

/*
 * Helper function of snprintf where buf is auto-incremented, size is auto-
 * decremented, and there is no return value.
 *
 * NOTE: buf and size must be l-values (e.g. variables)
 */
#define SNPRINTF(buf, size, format, ...) \
	do { \
		if (size > 0) { \
			int ret; \
			ret = snprintf(buf, size, format, ## __VA_ARGS__); \
			if (ret > size) { \
				buf += size; \
				size = 0; \
			} else { \
				buf += ret; \
				size -= ret; \
			} \
		} \
	} while (0)

/*
 * Write out the power management statistics.
 */
static int msm_pm_read_proc
	(char *page, char **start, off_t off, int count, int *eof, void *data)
{
	unsigned int cpu = off / MSM_PM_STAT_COUNT;
	int id = off % MSM_PM_STAT_COUNT;
	char *p = page;

	if (count < 1024) {
		*start = (char *) 0;
		*eof = 0;
		return 0;
	}

	if (cpu < num_possible_cpus()) {
		unsigned long flags;
		struct msm_pm_time_stats *stats;
		int i;
		int64_t bucket_time;
		int64_t s;
		uint32_t ns;

		spin_lock_irqsave(&msm_pm_stats_lock, flags);
		stats = per_cpu(msm_pm_stats, cpu).stats;

		/* Skip the disabled ones */
		if (!stats[id].enabled) {
			*p = '\0';
			p++;
			goto again;
		}

		s = stats[id].total_time;
		ns = do_div(s, NSEC_PER_SEC);
		SNPRINTF(p, count,
			"[cpu %u] %s:\n"
			"  count: %7d\n"
			"  total_time: %lld.%09u\n",
			cpu, stats[id].name,
			stats[id].count,
			s, ns);

		bucket_time = stats[id].first_bucket_time;
		for (i = 0; i < CONFIG_MSM_IDLE_STATS_BUCKET_COUNT - 1; i++) {
			s = bucket_time;
			ns = do_div(s, NSEC_PER_SEC);
			SNPRINTF(p, count,
				"   <%6lld.%09u: %7d (%lld-%lld)\n",
				s, ns, stats[id].bucket[i],
				stats[id].min_time[i],
				stats[id].max_time[i]);

			bucket_time <<= CONFIG_MSM_IDLE_STATS_BUCKET_SHIFT;
		}

		SNPRINTF(p, count, "  >=%6lld.%09u: %7d (%lld-%lld)\n",
			s, ns, stats[id].bucket[i],
			stats[id].min_time[i],
			stats[id].max_time[i]);

again:
		*start = (char *) 1;
		*eof = (off + 1 >= MSM_PM_STAT_COUNT * num_possible_cpus());

		spin_unlock_irqrestore(&msm_pm_stats_lock, flags);
	}

	return p - page;
}
#undef SNPRINTF

#define MSM_PM_STATS_RESET "reset"

/*
 * Reset the power management statistics values.
 */
static int msm_pm_write_proc(struct file *file, const char __user *buffer,
	unsigned long count, void *data)
{
	char buf[sizeof(MSM_PM_STATS_RESET)];
	int ret;
	unsigned long flags;
	unsigned int cpu;
	size_t len = strnlen(MSM_PM_STATS_RESET, sizeof(MSM_PM_STATS_RESET));

	if (count < sizeof(MSM_PM_STATS_RESET)) {
		ret = -EINVAL;
		goto write_proc_failed;
	}

	if (copy_from_user(buf, buffer, len)) {
		ret = -EFAULT;
		goto write_proc_failed;
	}

	if (strncmp(buf, MSM_PM_STATS_RESET, len)) {
		ret = -EINVAL;
		goto write_proc_failed;
	}

	spin_lock_irqsave(&msm_pm_stats_lock, flags);
	for_each_possible_cpu(cpu) {
		struct msm_pm_time_stats *stats;
		int i;

		stats = per_cpu(msm_pm_stats, cpu).stats;
		for (i = 0; i < MSM_PM_STAT_COUNT; i++) {
			memset(stats[i].bucket,
				0, sizeof(stats[i].bucket));
			memset(stats[i].min_time,
				0, sizeof(stats[i].min_time));
			memset(stats[i].max_time,
				0, sizeof(stats[i].max_time));
			stats[i].count = 0;
			stats[i].total_time = 0;
		}
	}

	spin_unlock_irqrestore(&msm_pm_stats_lock, flags);
	return count;

write_proc_failed:
	return ret;
}
#undef MSM_PM_STATS_RESET

void msm_pm_add_stats(enum msm_pm_time_stats_id *enable_stats, int size)
{
	unsigned int cpu;
	struct proc_dir_entry *d_entry;
	int i = 0;

	for_each_possible_cpu(cpu) {
		struct msm_pm_time_stats *stats =
			per_cpu(msm_pm_stats, cpu).stats;

		stats[MSM_PM_STAT_REQUESTED_IDLE].name = "idle-request";
		stats[MSM_PM_STAT_REQUESTED_IDLE].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_SPIN].name = "idle-spin";
		stats[MSM_PM_STAT_IDLE_SPIN].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_WFI].name = "idle-wfi";
		stats[MSM_PM_STAT_IDLE_WFI].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_RETENTION].name = "retention";
		stats[MSM_PM_STAT_RETENTION].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_STANDALONE_POWER_COLLAPSE].name =
			"idle-standalone-power-collapse";
		stats[MSM_PM_STAT_IDLE_STANDALONE_POWER_COLLAPSE].
			first_bucket_time = CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_FAILED_STANDALONE_POWER_COLLAPSE].name =
			"idle-failed-standalone-power-collapse";
		stats[MSM_PM_STAT_IDLE_FAILED_STANDALONE_POWER_COLLAPSE].
			first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_POWER_COLLAPSE].name =
			"idle-power-collapse";
		stats[MSM_PM_STAT_IDLE_POWER_COLLAPSE].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_IDLE_FAILED_POWER_COLLAPSE].name =
			"idle-failed-power-collapse";
		stats[MSM_PM_STAT_IDLE_FAILED_POWER_COLLAPSE].
			first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_SUSPEND].name = "suspend";
		stats[MSM_PM_STAT_SUSPEND].first_bucket_time =
			CONFIG_MSM_SUSPEND_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_FAILED_SUSPEND].name = "failed-suspend";
		stats[MSM_PM_STAT_FAILED_SUSPEND].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		stats[MSM_PM_STAT_NOT_IDLE].name = "not-idle";
		stats[MSM_PM_STAT_NOT_IDLE].first_bucket_time =
			CONFIG_MSM_IDLE_STATS_FIRST_BUCKET;

		for (i = 0; i < size; i++)
			stats[enable_stats[i]].enabled = true;

	}

	d_entry = create_proc_entry("msm_pm_stats",
			S_IRUGO | S_IWUSR | S_IWGRP, NULL);
	if (d_entry) {
		d_entry->read_proc = msm_pm_read_proc;
		d_entry->write_proc = msm_pm_write_proc;
		d_entry->data = NULL;
	}
}