/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/

#include "ttm/ttm_memory.h"
#include "ttm/ttm_module.h"
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/module.h>

#define TTM_MEMORY_ALLOC_RETRIES 4

struct ttm_mem_zone {
        struct kobject kobj;
        struct ttm_mem_global *glob;
        const char *name;
        uint64_t zone_mem;
        uint64_t emer_mem;
        uint64_t max_mem;
        uint64_t swap_limit;
        uint64_t used_mem;
};

static struct attribute ttm_mem_sys = {
        .name = "zone_memory",
        .mode = S_IRUGO
};
static struct attribute ttm_mem_emer = {
        .name = "emergency_memory",
        .mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_mem_max = {
        .name = "available_memory",
        .mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_mem_swap = {
        .name = "swap_limit",
        .mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_mem_used = {
        .name = "used_memory",
        .mode = S_IRUGO
};

static void ttm_mem_zone_kobj_release(struct kobject *kobj)
{
        struct ttm_mem_zone *zone =
                container_of(kobj, struct ttm_mem_zone, kobj);

        printk(KERN_INFO TTM_PFX
               "Zone %7s: Used memory at exit: %llu kiB.\n",
               zone->name, (unsigned long long) zone->used_mem >> 10);
        kfree(zone);
}

static ssize_t ttm_mem_zone_show(struct kobject *kobj,
                                 struct attribute *attr,
                                 char *buffer)
{
        struct ttm_mem_zone *zone =
                container_of(kobj, struct ttm_mem_zone, kobj);
        uint64_t val = 0;

        spin_lock(&zone->glob->lock);
        if (attr == &ttm_mem_sys)
                val = zone->zone_mem;
        else if (attr == &ttm_mem_emer)
                val = zone->emer_mem;
        else if (attr == &ttm_mem_max)
                val = zone->max_mem;
        else if (attr == &ttm_mem_swap)
                val = zone->swap_limit;
        else if (attr == &ttm_mem_used)
                val = zone->used_mem;
        spin_unlock(&zone->glob->lock);

        return snprintf(buffer, PAGE_SIZE, "%llu\n",
                        (unsigned long long) val >> 10);
}

static void ttm_check_swapping(struct ttm_mem_global *glob);

static ssize_t ttm_mem_zone_store(struct kobject *kobj,
                                  struct attribute *attr,
                                  const char *buffer,
                                  size_t size)
{
        struct ttm_mem_zone *zone =
                container_of(kobj, struct ttm_mem_zone, kobj);
        int chars;
        unsigned long val;
        uint64_t val64;

        chars = sscanf(buffer, "%lu", &val);
        if (chars == 0)
                return size;

        val64 = val;
        val64 <<= 10;

        spin_lock(&zone->glob->lock);
        if (val64 > zone->zone_mem)
                val64 = zone->zone_mem;
        if (attr == &ttm_mem_emer) {
                zone->emer_mem = val64;
                if (zone->max_mem > val64)
                        zone->max_mem = val64;
        } else if (attr == &ttm_mem_max) {
                zone->max_mem = val64;
                if (zone->emer_mem < val64)
                        zone->emer_mem = val64;
        } else if (attr == &ttm_mem_swap)
                zone->swap_limit = val64;
        spin_unlock(&zone->glob->lock);

        ttm_check_swapping(zone->glob);

        return size;
}

static struct attribute *ttm_mem_zone_attrs[] = {
        &ttm_mem_sys,
        &ttm_mem_emer,
        &ttm_mem_max,
        &ttm_mem_swap,
        &ttm_mem_used,
        NULL
};

static struct sysfs_ops ttm_mem_zone_ops = {
        .show = &ttm_mem_zone_show,
        .store = &ttm_mem_zone_store
};

static struct kobj_type ttm_mem_zone_kobj_type = {
        .release = &ttm_mem_zone_kobj_release,
        .sysfs_ops = &ttm_mem_zone_ops,
        .default_attrs = ttm_mem_zone_attrs,
};

static void ttm_mem_global_kobj_release(struct kobject *kobj)
{
        struct ttm_mem_global *glob =
                container_of(kobj, struct ttm_mem_global, kobj);

        kfree(glob);
}

static struct kobj_type ttm_mem_glob_kobj_type = {
        .release = &ttm_mem_global_kobj_release,
};

static bool ttm_zones_above_swap_target(struct ttm_mem_global *glob,
                                        bool from_wq, uint64_t extra)
{
        unsigned int i;
        struct ttm_mem_zone *zone;
        uint64_t target;

        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];

                if (from_wq)
                        target = zone->swap_limit;
                else if (capable(CAP_SYS_ADMIN))
                        target = zone->emer_mem;
                else
                        target = zone->max_mem;

                target = (extra > target) ? 0ULL : target;

                if (zone->used_mem > target)
                        return true;
        }
        return false;
}

/**
 * At this point we only support a single shrink callback.
 * Extend this if needed, perhaps using a linked list of callbacks.
 * Note that this function is reentrant:
 * many threads may try to swap out at any given time.
 */

static void ttm_shrink(struct ttm_mem_global *glob, bool from_wq,
                       uint64_t extra)
{
        int ret;
        struct ttm_mem_shrink *shrink;

        spin_lock(&glob->lock);
        if (glob->shrink == NULL)
                goto out;

        while (ttm_zones_above_swap_target(glob, from_wq, extra)) {
                shrink = glob->shrink;
                spin_unlock(&glob->lock);
                ret = shrink->do_shrink(shrink);
                spin_lock(&glob->lock);
                if (unlikely(ret != 0))
                        goto out;
        }
out:
        spin_unlock(&glob->lock);
}



static void ttm_shrink_work(struct work_struct *work)
{
        struct ttm_mem_global *glob =
            container_of(work, struct ttm_mem_global, work);

        ttm_shrink(glob, true, 0ULL);
}

static int ttm_mem_init_kernel_zone(struct ttm_mem_global *glob,
                                    const struct sysinfo *si)
{
        struct ttm_mem_zone *zone = kzalloc(sizeof(*zone), GFP_KERNEL);
        uint64_t mem;
        int ret;

        if (unlikely(!zone))
                return -ENOMEM;

        mem = si->totalram - si->totalhigh;
        mem *= si->mem_unit;

        zone->name = "kernel";
        zone->zone_mem = mem;
        zone->max_mem = mem >> 1;
        zone->emer_mem = (mem >> 1) + (mem >> 2);
        zone->swap_limit = zone->max_mem - (mem >> 3);
        zone->used_mem = 0;
        zone->glob = glob;
        glob->zone_kernel = zone;
        kobject_init(&zone->kobj, &ttm_mem_zone_kobj_type);
        ret = kobject_add(&zone->kobj, &glob->kobj, zone->name);
        if (unlikely(ret != 0)) {
                kobject_put(&zone->kobj);
                return ret;
        }
        glob->zones[glob->num_zones++] = zone;
        return 0;
}

#ifdef CONFIG_HIGHMEM
static int ttm_mem_init_highmem_zone(struct ttm_mem_global *glob,
                                     const struct sysinfo *si)
{
        struct ttm_mem_zone *zone = kzalloc(sizeof(*zone), GFP_KERNEL);
        uint64_t mem;
        int ret;

        if (unlikely(!zone))
                return -ENOMEM;

        if (si->totalhigh == 0)
                return 0;

        mem = si->totalram;
        mem *= si->mem_unit;

        zone->name = "highmem";
        zone->zone_mem = mem;
        zone->max_mem = mem >> 1;
        zone->emer_mem = (mem >> 1) + (mem >> 2);
        zone->swap_limit = zone->max_mem - (mem >> 3);
        zone->used_mem = 0;
        zone->glob = glob;
        glob->zone_highmem = zone;
        kobject_init(&zone->kobj, &ttm_mem_zone_kobj_type);
        ret = kobject_add(&zone->kobj, &glob->kobj, zone->name);
        if (unlikely(ret != 0)) {
                kobject_put(&zone->kobj);
                return ret;
        }
        glob->zones[glob->num_zones++] = zone;
        return 0;
}
#else
static int ttm_mem_init_dma32_zone(struct ttm_mem_global *glob,
                                   const struct sysinfo *si)
{
        struct ttm_mem_zone *zone = kzalloc(sizeof(*zone), GFP_KERNEL);
        uint64_t mem;
        int ret;

        if (unlikely(!zone))
                return -ENOMEM;

        mem = si->totalram;
        mem *= si->mem_unit;

        /**
         * No special dma32 zone needed.
         */

        if (mem <= ((uint64_t) 1ULL << 32))
                return 0;

        /*
         * Limit max dma32 memory to 4GB for now
         * until we can figure out how big this
         * zone really is.
         */

        mem = ((uint64_t) 1ULL << 32);
        zone->name = "dma32";
        zone->zone_mem = mem;
        zone->max_mem = mem >> 1;
        zone->emer_mem = (mem >> 1) + (mem >> 2);
        zone->swap_limit = zone->max_mem - (mem >> 3);
        zone->used_mem = 0;
        zone->glob = glob;
        glob->zone_dma32 = zone;
        kobject_init(&zone->kobj, &ttm_mem_zone_kobj_type);
        ret = kobject_add(&zone->kobj, &glob->kobj, zone->name);
        if (unlikely(ret != 0)) {
                kobject_put(&zone->kobj);
                return ret;
        }
        glob->zones[glob->num_zones++] = zone;
        return 0;
}
#endif

int ttm_mem_global_init(struct ttm_mem_global *glob)
{
        struct sysinfo si;
        int ret;
        int i;
        struct ttm_mem_zone *zone;

        spin_lock_init(&glob->lock);
        glob->swap_queue = create_singlethread_workqueue("ttm_swap");
        INIT_WORK(&glob->work, ttm_shrink_work);
        init_waitqueue_head(&glob->queue);
        kobject_init(&glob->kobj, &ttm_mem_glob_kobj_type);
        ret = kobject_add(&glob->kobj,
                          ttm_get_kobj(),
                          "memory_accounting");
        if (unlikely(ret != 0)) {
                kobject_put(&glob->kobj);
                return ret;
        }

        si_meminfo(&si);

        ret = ttm_mem_init_kernel_zone(glob, &si);
        if (unlikely(ret != 0))
                goto out_no_zone;
#ifdef CONFIG_HIGHMEM
        ret = ttm_mem_init_highmem_zone(glob, &si);
        if (unlikely(ret != 0))
                goto out_no_zone;
#else
        ret = ttm_mem_init_dma32_zone(glob, &si);
        if (unlikely(ret != 0))
                goto out_no_zone;
#endif
        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];
                printk(KERN_INFO TTM_PFX
                       "Zone %7s: Available graphics memory: %llu kiB.\n",
                       zone->name, (unsigned long long) zone->max_mem >> 10);
        }
        return 0;
out_no_zone:
        ttm_mem_global_release(glob);
        return ret;
}
EXPORT_SYMBOL(ttm_mem_global_init);

void ttm_mem_global_release(struct ttm_mem_global *glob)
{
        unsigned int i;
        struct ttm_mem_zone *zone;

        flush_workqueue(glob->swap_queue);
        destroy_workqueue(glob->swap_queue);
        glob->swap_queue = NULL;
        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];
                kobject_del(&zone->kobj);
                kobject_put(&zone->kobj);
        }
        kobject_del(&glob->kobj);
        kobject_put(&glob->kobj);
}
EXPORT_SYMBOL(ttm_mem_global_release);

static void ttm_check_swapping(struct ttm_mem_global *glob)
{
        bool needs_swapping = false;
        unsigned int i;
        struct ttm_mem_zone *zone;

        spin_lock(&glob->lock);
        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];
                if (zone->used_mem > zone->swap_limit) {
                        needs_swapping = true;
                        break;
                }
        }

        spin_unlock(&glob->lock);

        if (unlikely(needs_swapping))
                (void)queue_work(glob->swap_queue, &glob->work);

}

static void ttm_mem_global_free_zone(struct ttm_mem_global *glob,
                                     struct ttm_mem_zone *single_zone,
                                     uint64_t amount)
{
        unsigned int i;
        struct ttm_mem_zone *zone;

        spin_lock(&glob->lock);
        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];
                if (single_zone && zone != single_zone)
                        continue;
                zone->used_mem -= amount;
        }
        spin_unlock(&glob->lock);
}

void ttm_mem_global_free(struct ttm_mem_global *glob,
                         uint64_t amount)
{
        return ttm_mem_global_free_zone(glob, NULL, amount);
}

static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
                                  struct ttm_mem_zone *single_zone,
                                  uint64_t amount, bool reserve)
{
        uint64_t limit;
        int ret = -ENOMEM;
        unsigned int i;
        struct ttm_mem_zone *zone;

        spin_lock(&glob->lock);
        for (i = 0; i < glob->num_zones; ++i) {
                zone = glob->zones[i];
                if (single_zone && zone != single_zone)
                        continue;

                limit = (capable(CAP_SYS_ADMIN)) ?
                        zone->emer_mem : zone->max_mem;

                if (zone->used_mem > limit)
                        goto out_unlock;
        }

        if (reserve) {
                for (i = 0; i < glob->num_zones; ++i) {
                        zone = glob->zones[i];
                        if (single_zone && zone != single_zone)
                                continue;
                        zone->used_mem += amount;
                }
        }

        ret = 0;
out_unlock:
        spin_unlock(&glob->lock);
        ttm_check_swapping(glob);

        return ret;
}


static int ttm_mem_global_alloc_zone(struct ttm_mem_global *glob,
                                     struct ttm_mem_zone *single_zone,
                                     uint64_t memory,
                                     bool no_wait, bool interruptible)
{
        int count = TTM_MEMORY_ALLOC_RETRIES;

        while (unlikely(ttm_mem_global_reserve(glob,
                                               single_zone,
                                               memory, true)
                        != 0)) {
                if (no_wait)
                        return -ENOMEM;
                if (unlikely(count-- == 0))
                        return -ENOMEM;
                ttm_shrink(glob, false, memory + (memory >> 2) + 16);
        }

        return 0;
}

int ttm_mem_global_alloc(struct ttm_mem_global *glob, uint64_t memory,
                         bool no_wait, bool interruptible)
{
        /**
         * Normal allocations of kernel memory are registered in
         * all zones.
         */

        return ttm_mem_global_alloc_zone(glob, NULL, memory, no_wait,
                                         interruptible);
}

int ttm_mem_global_alloc_page(struct ttm_mem_global *glob,
                              struct page *page,
                              bool no_wait, bool interruptible)
{

        struct ttm_mem_zone *zone = NULL;

        /**
         * Page allocations may be registed in a single zone
         * only if highmem or !dma32.
         */

#ifdef CONFIG_HIGHMEM
        if (PageHighMem(page) && glob->zone_highmem != NULL)
                zone = glob->zone_highmem;
#else
        if (glob->zone_dma32 && page_to_pfn(page) > 0x00100000UL)
                zone = glob->zone_kernel;
#endif
        return ttm_mem_global_alloc_zone(glob, zone, PAGE_SIZE, no_wait,
                                         interruptible);
}

void ttm_mem_global_free_page(struct ttm_mem_global *glob, struct page *page)
{
        struct ttm_mem_zone *zone = NULL;

#ifdef CONFIG_HIGHMEM
        if (PageHighMem(page) && glob->zone_highmem != NULL)
                zone = glob->zone_highmem;
#else
        if (glob->zone_dma32 && page_to_pfn(page) > 0x00100000UL)
                zone = glob->zone_kernel;
#endif
        ttm_mem_global_free_zone(glob, zone, PAGE_SIZE);
}


size_t ttm_round_pot(size_t size)
{
        if ((size & (size - 1)) == 0)
                return size;
        else if (size > PAGE_SIZE)
                return PAGE_ALIGN(size);
        else {
                size_t tmp_size = 4;

                while (tmp_size < size)
                        tmp_size <<= 1;

                return tmp_size;
        }
        return 0;
}