/*
 * Copyright (C) 2013 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* For profiling, userspace can:
 *
 *   tail -f /sys/kernel/debug/dri/<minor>/gpu
 *
 * This will enable performance counters/profiling to track the busy time
 * and any gpu specific performance counters that are supported.
 */

#ifdef CONFIG_DEBUG_FS

#include <linux/debugfs.h>

#include "msm_drv.h"
#include "msm_gpu.h"

struct msm_perf_state {
        struct drm_device *dev;

        bool open;
        int cnt;
        struct mutex read_lock;

        char buf[256];
        int buftot, bufpos;

        unsigned long next_jiffies;
};

#define SAMPLE_TIME (HZ/4)

/* wait for next sample time: */
static int wait_sample(struct msm_perf_state *perf)
{
        unsigned long start_jiffies = jiffies;

        if (time_after(perf->next_jiffies, start_jiffies)) {
                unsigned long remaining_jiffies =
                        perf->next_jiffies - start_jiffies;
                int ret = schedule_timeout_interruptible(remaining_jiffies);
                if (ret > 0) {
                        /* interrupted */
                        return -ERESTARTSYS;
                }
        }
        perf->next_jiffies += SAMPLE_TIME;
        return 0;
}

static int refill_buf(struct msm_perf_state *perf)
{
        struct msm_drm_private *priv = perf->dev->dev_private;
        struct msm_gpu *gpu = priv->gpu;
        char *ptr = perf->buf;
        int rem = sizeof(perf->buf);
        int i, n;

        if ((perf->cnt++ % 32) == 0) {
                /* Header line: */
                n = snprintf(ptr, rem, "%%BUSY");
                ptr += n;
                rem -= n;

                for (i = 0; i < gpu->num_perfcntrs; i++) {
                        const struct msm_gpu_perfcntr *perfcntr = &gpu->perfcntrs[i];
                        n = snprintf(ptr, rem, "\t%s", perfcntr->name);
                        ptr += n;
                        rem -= n;
                }
        } else {
                /* Sample line: */
                uint32_t activetime = 0, totaltime = 0;
                uint32_t cntrs[5];
                uint32_t val;
                int ret;

                /* sleep until next sample time: */
                ret = wait_sample(perf);
                if (ret)
                        return ret;

                ret = msm_gpu_perfcntr_sample(gpu, &activetime, &totaltime,
                                ARRAY_SIZE(cntrs), cntrs);
                if (ret < 0)
                        return ret;

                val = totaltime ? 1000 * activetime / totaltime : 0;
                n = snprintf(ptr, rem, "%3d.%d%%", val / 10, val % 10);
                ptr += n;
                rem -= n;

                for (i = 0; i < ret; i++) {
                        /* cycle counters (I think).. convert to MHz.. */
                        val = cntrs[i] / 10000;
                        n = snprintf(ptr, rem, "\t%5d.%02d",
                                        val / 100, val % 100);
                        ptr += n;
                        rem -= n;
                }
        }

        n = snprintf(ptr, rem, "\n");
        ptr += n;
        rem -= n;

        perf->bufpos = 0;
        perf->buftot = ptr - perf->buf;

        return 0;
}

static ssize_t perf_read(struct file *file, char __user *buf,
                size_t sz, loff_t *ppos)
{
        struct msm_perf_state *perf = file->private_data;
        int n = 0, ret = 0;

        mutex_lock(&perf->read_lock);

        if (perf->bufpos >= perf->buftot) {
                ret = refill_buf(perf);
                if (ret)
                        goto out;
        }

        n = min((int)sz, perf->buftot - perf->bufpos);
        if (copy_to_user(buf, &perf->buf[perf->bufpos], n)) {
                ret = -EFAULT;
                goto out;
        }

        perf->bufpos += n;
        *ppos += n;

out:
        mutex_unlock(&perf->read_lock);
        if (ret)
                return ret;
        return n;
}

static int perf_open(struct inode *inode, struct file *file)
{
        struct msm_perf_state *perf = inode->i_private;
        struct drm_device *dev = perf->dev;
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_gpu *gpu = priv->gpu;
        int ret = 0;

        mutex_lock(&dev->struct_mutex);

        if (perf->open || !gpu) {
                ret = -EBUSY;
                goto out;
        }

        file->private_data = perf;
        perf->open = true;
        perf->cnt = 0;
        perf->buftot = 0;
        perf->bufpos = 0;
        msm_gpu_perfcntr_start(gpu);
        perf->next_jiffies = jiffies + SAMPLE_TIME;

out:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static int perf_release(struct inode *inode, struct file *file)
{
        struct msm_perf_state *perf = inode->i_private;
        struct msm_drm_private *priv = perf->dev->dev_private;
        msm_gpu_perfcntr_stop(priv->gpu);
        perf->open = false;
        return 0;
}


static const struct file_operations perf_debugfs_fops = {
        .owner = THIS_MODULE,
        .open = perf_open,
        .read = perf_read,
        .llseek = no_llseek,
        .release = perf_release,
};

int msm_perf_debugfs_init(struct drm_minor *minor)
{
        struct msm_drm_private *priv = minor->dev->dev_private;
        struct msm_perf_state *perf;
        struct dentry *ent;

        /* only create on first minor: */
        if (priv->perf)
                return 0;

        perf = kzalloc(sizeof(*perf), GFP_KERNEL);
        if (!perf)
                return -ENOMEM;

        perf->dev = minor->dev;

        mutex_init(&perf->read_lock);
        priv->perf = perf;

        ent = debugfs_create_file("perf", S_IFREG | S_IRUGO,
                        minor->debugfs_root, perf, &perf_debugfs_fops);
        if (!ent) {
                DRM_ERROR("Cannot create /sys/kernel/debug/dri/%pd/perf\n",
                                minor->debugfs_root);
                goto fail;
        }

        return 0;

fail:
        msm_perf_debugfs_cleanup(priv);
        return -1;
}

void msm_perf_debugfs_cleanup(struct msm_drm_private *priv)
{
        struct msm_perf_state *perf = priv->perf;

        if (!perf)
                return;

        priv->perf = NULL;

        mutex_destroy(&perf->read_lock);

        kfree(perf);
}

#endif