// SPDX-License-Identifier: GPL-2.0
/*
 * CMA DebugFS Interface
 *
 * Copyright (c) 2015 Sasha Levin <sasha.levin@oracle.com>
 */


#include <linux/debugfs.h>
#include <linux/cma.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm_types.h>

#include "cma.h"

struct cma_mem {
        struct hlist_node node;
        struct page *p;
        unsigned long n;
};

static int cma_debugfs_get(void *data, u64 *val)
{
        unsigned long *p = data;

        *val = *p;

        return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");

static int cma_used_get(void *data, u64 *val)
{
        struct cma *cma = data;

        spin_lock_irq(&cma->lock);
        *val = cma->count - cma->available_count;
        spin_unlock_irq(&cma->lock);

        return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu\n");

static int cma_maxchunk_get(void *data, u64 *val)
{
        struct cma *cma = data;
        struct cma_memrange *cmr;
        unsigned long maxchunk = 0;
        unsigned long start, end;
        unsigned long bitmap_maxno;
        int r;

        spin_lock_irq(&cma->lock);
        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                bitmap_maxno = cma_bitmap_maxno(cma, cmr);
                for_each_clear_bitrange(start, end, cmr->bitmap, bitmap_maxno)
                        maxchunk = max(end - start, maxchunk);
        }
        spin_unlock_irq(&cma->lock);
        *val = (u64)maxchunk << cma->order_per_bit;

        return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(cma_maxchunk_fops, cma_maxchunk_get, NULL, "%llu\n");

static void cma_add_to_cma_mem_list(struct cma *cma, struct cma_mem *mem)
{
        spin_lock(&cma->mem_head_lock);
        hlist_add_head(&mem->node, &cma->mem_head);
        spin_unlock(&cma->mem_head_lock);
}

static struct cma_mem *cma_get_entry_from_list(struct cma *cma)
{
        struct cma_mem *mem = NULL;

        spin_lock(&cma->mem_head_lock);
        if (!hlist_empty(&cma->mem_head)) {
                mem = hlist_entry(cma->mem_head.first, struct cma_mem, node);
                hlist_del_init(&mem->node);
        }
        spin_unlock(&cma->mem_head_lock);

        return mem;
}

static int cma_free_mem(struct cma *cma, int count)
{
        struct cma_mem *mem = NULL;

        while (count) {
                mem = cma_get_entry_from_list(cma);
                if (mem == NULL)
                        return 0;

                if (mem->n <= count) {
                        cma_release(cma, mem->p, mem->n);
                        count -= mem->n;
                        kfree(mem);
                } else if (cma->order_per_bit == 0) {
                        cma_release(cma, mem->p, count);
                        mem->p += count;
                        mem->n -= count;
                        count = 0;
                        cma_add_to_cma_mem_list(cma, mem);
                } else {
                        pr_debug("cma: cannot release partial block when order_per_bit != 0\n");
                        cma_add_to_cma_mem_list(cma, mem);
                        break;
                }
        }

        return 0;

}

static int cma_free_write(void *data, u64 val)
{
        int pages = val;
        struct cma *cma = data;

        return cma_free_mem(cma, pages);
}
DEFINE_DEBUGFS_ATTRIBUTE(cma_free_fops, NULL, cma_free_write, "%llu\n");

static int cma_alloc_mem(struct cma *cma, int count)
{
        struct cma_mem *mem;
        struct page *p;

        mem = kzalloc_obj(*mem);
        if (!mem)
                return -ENOMEM;

        p = cma_alloc(cma, count, 0, false);
        if (!p) {
                kfree(mem);
                return -ENOMEM;
        }

        mem->p = p;
        mem->n = count;

        cma_add_to_cma_mem_list(cma, mem);

        return 0;
}

static int cma_alloc_write(void *data, u64 val)
{
        int pages = val;
        struct cma *cma = data;

        return cma_alloc_mem(cma, pages);
}
DEFINE_DEBUGFS_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");

static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry)
{
        struct dentry *tmp, *dir, *rangedir;
        int r;
        char rdirname[12];
        struct cma_memrange *cmr;

        tmp = debugfs_create_dir(cma->name, root_dentry);

        debugfs_create_file("alloc", 0200, tmp, cma, &cma_alloc_fops);
        debugfs_create_file("free", 0200, tmp, cma, &cma_free_fops);
        debugfs_create_file("count", 0444, tmp, &cma->count, &cma_debugfs_fops);
        debugfs_create_file("order_per_bit", 0444, tmp,
                            &cma->order_per_bit, &cma_debugfs_fops);
        debugfs_create_file("used", 0444, tmp, cma, &cma_used_fops);
        debugfs_create_file("maxchunk", 0444, tmp, cma, &cma_maxchunk_fops);

        rangedir = debugfs_create_dir("ranges", tmp);
        for (r = 0; r < cma->nranges; r++) {
                cmr = &cma->ranges[r];
                snprintf(rdirname, sizeof(rdirname), "%d", r);
                dir = debugfs_create_dir(rdirname, rangedir);
                debugfs_create_file("base_pfn", 0444, dir,
                            &cmr->base_pfn, &cma_debugfs_fops);
                cmr->dfs_bitmap.array = (u32 *)cmr->bitmap;
                cmr->dfs_bitmap.n_elements =
                        DIV_ROUND_UP(cma_bitmap_maxno(cma, cmr),
                                        BITS_PER_BYTE * sizeof(u32));
                debugfs_create_u32_array("bitmap", 0444, dir,
                                &cmr->dfs_bitmap);
        }

        /*
         * Backward compatible symlinks to range 0 for base_pfn and bitmap.
         */
        debugfs_create_symlink("base_pfn", tmp, "ranges/0/base_pfn");
        debugfs_create_symlink("bitmap", tmp, "ranges/0/bitmap");
}

static int __init cma_debugfs_init(void)
{
        struct dentry *cma_debugfs_root;
        int i;

        cma_debugfs_root = debugfs_create_dir("cma", NULL);

        for (i = 0; i < cma_area_count; i++)
                cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root);

        return 0;
}
late_initcall(cma_debugfs_init);