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    /*
     * 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 struct dentry *cma_debugfs_root;
    
    static int cma_debugfs_get(void *data, u64 *val)
    {
    	unsigned long *p = data;
    
    	*val = *p;
    
    	return 0;
    }
    DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
    
    static int cma_used_get(void *data, u64 *val)
    {
    	struct cma *cma = data;
    	unsigned long used;
    
    	mutex_lock(&cma->lock);
    	/* pages counter is smaller than sizeof(int) */
    	used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
    	mutex_unlock(&cma->lock);
    	*val = (u64)used << cma->order_per_bit;
    
    	return 0;
    }
    DEFINE_SIMPLE_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu\n");
    
    static int cma_maxchunk_get(void *data, u64 *val)
    {
    	struct cma *cma = data;
    	unsigned long maxchunk = 0;
    	unsigned long start, end = 0;
    	unsigned long bitmap_maxno = cma_bitmap_maxno(cma);
    
    	mutex_lock(&cma->lock);
    	for (;;) {
    		start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
    		if (start >= cma->count)
    			break;
    		end = find_next_bit(cma->bitmap, bitmap_maxno, start);
    		maxchunk = max(end - start, maxchunk);
    	}
    	mutex_unlock(&cma->lock);
    	*val = (u64)maxchunk << cma->order_per_bit;
    
    	return 0;
    }
    DEFINE_SIMPLE_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_SIMPLE_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(sizeof(*mem), GFP_KERNEL);
    	if (!mem)
    		return -ENOMEM;
    
    	p = cma_alloc(cma, count, 0);
    	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_SIMPLE_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");
    
    static void cma_debugfs_add_one(struct cma *cma, int idx)
    {
    	struct dentry *tmp;
    	char name[16];
    	int u32s;
    
    	sprintf(name, "cma-%d", idx);
    
    	tmp = debugfs_create_dir(name, cma_debugfs_root);
    
    	debugfs_create_file("alloc", S_IWUSR, tmp, cma,
    				&cma_alloc_fops);
    
    	debugfs_create_file("free", S_IWUSR, tmp, cma,
    				&cma_free_fops);
    
    	debugfs_create_file("base_pfn", S_IRUGO, tmp,
    				&cma->base_pfn, &cma_debugfs_fops);
    	debugfs_create_file("count", S_IRUGO, tmp,
    				&cma->count, &cma_debugfs_fops);
    	debugfs_create_file("order_per_bit", S_IRUGO, tmp,
    				&cma->order_per_bit, &cma_debugfs_fops);
    	debugfs_create_file("used", S_IRUGO, tmp, cma, &cma_used_fops);
    	debugfs_create_file("maxchunk", S_IRUGO, tmp, cma, &cma_maxchunk_fops);
    
    	u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
    	debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap, u32s);
    }
    
    static int __init cma_debugfs_init(void)
    {
    	int i;
    
    	cma_debugfs_root = debugfs_create_dir("cma", NULL);
    	if (!cma_debugfs_root)
    		return -ENOMEM;
    
    	for (i = 0; i < cma_area_count; i++)
    		cma_debugfs_add_one(&cma_areas[i], i);
    
    	return 0;
    }
    late_initcall(cma_debugfs_init);