// 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
  ");

  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_DEBUGFS_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu
  ");

  
  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 >= bitmap_maxno)

  			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_DEBUGFS_ATTRIBUTE(cma_maxchunk_fops, cma_maxchunk_get, NULL, "%llu
  ");

  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
  ");
  			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
  ");

  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, 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
  ");

  static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry)

  {
  	struct dentry *tmp;
  	char name[16];

  	scnprintf(name, sizeof(name), "cma-%s", cma->name);

  	tmp = debugfs_create_dir(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("base_pfn", 0444, tmp,
  			    &cma->base_pfn, &cma_debugfs_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);

  	cma->dfs_bitmap.array = (u32 *)cma->bitmap;
  	cma->dfs_bitmap.n_elements = DIV_ROUND_UP(cma_bitmap_maxno(cma),
  						  BITS_PER_BYTE * sizeof(u32));
  	debugfs_create_u32_array("bitmap", 0444, tmp, &cma->dfs_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);