/*
   * Contiguous Memory Allocator
   *
   * Copyright (c) 2010-2011 by Samsung Electronics.
   * Copyright IBM Corporation, 2013
   * Copyright LG Electronics Inc., 2014
   * Written by:
   *	Marek Szyprowski <m.szyprowski@samsung.com>
   *	Michal Nazarewicz <mina86@mina86.com>
   *	Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   *	Joonsoo Kim <iamjoonsoo.kim@lge.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License or (at your optional) any later version of the license.
   */
  
  #define pr_fmt(fmt) "cma: " fmt
  
  #ifdef CONFIG_CMA_DEBUG
  #ifndef DEBUG
  #  define DEBUG
  #endif
  #endif
  
  #include <linux/memblock.h>
  #include <linux/err.h>
  #include <linux/mm.h>
  #include <linux/mutex.h>
  #include <linux/sizes.h>
  #include <linux/slab.h>
  #include <linux/log2.h>
  #include <linux/cma.h>

  #include <linux/highmem.h>

  #include <linux/io.h>

  
  struct cma {
  	unsigned long	base_pfn;
  	unsigned long	count;
  	unsigned long	*bitmap;
  	unsigned int order_per_bit; /* Order of pages represented by one bit */
  	struct mutex	lock;
  };
  
  static struct cma cma_areas[MAX_CMA_AREAS];
  static unsigned cma_area_count;
  static DEFINE_MUTEX(cma_mutex);
  
  phys_addr_t cma_get_base(struct cma *cma)
  {
  	return PFN_PHYS(cma->base_pfn);
  }
  
  unsigned long cma_get_size(struct cma *cma)
  {
  	return cma->count << PAGE_SHIFT;
  }
  
  static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
  {

  	if (align_order <= cma->order_per_bit)
  		return 0;
  	return (1UL << (align_order - cma->order_per_bit)) - 1;

  }

  static unsigned long cma_bitmap_aligned_offset(struct cma *cma, int align_order)
  {
  	unsigned int alignment;
  
  	if (align_order <= cma->order_per_bit)
  		return 0;
  	alignment = 1UL << (align_order - cma->order_per_bit);
  	return ALIGN(cma->base_pfn, alignment) -
  		(cma->base_pfn >> cma->order_per_bit);
  }

  static unsigned long cma_bitmap_maxno(struct cma *cma)
  {
  	return cma->count >> cma->order_per_bit;
  }
  
  static unsigned long cma_bitmap_pages_to_bits(struct cma *cma,
  						unsigned long pages)
  {
  	return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
  }
  
  static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count)
  {
  	unsigned long bitmap_no, bitmap_count;
  
  	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
  	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
  
  	mutex_lock(&cma->lock);
  	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
  	mutex_unlock(&cma->lock);
  }
  
  static int __init cma_activate_area(struct cma *cma)
  {
  	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
  	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
  	unsigned i = cma->count >> pageblock_order;
  	struct zone *zone;
  
  	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  
  	if (!cma->bitmap)
  		return -ENOMEM;
  
  	WARN_ON_ONCE(!pfn_valid(pfn));
  	zone = page_zone(pfn_to_page(pfn));
  
  	do {
  		unsigned j;
  
  		base_pfn = pfn;
  		for (j = pageblock_nr_pages; j; --j, pfn++) {
  			WARN_ON_ONCE(!pfn_valid(pfn));
  			/*
  			 * alloc_contig_range requires the pfn range
  			 * specified to be in the same zone. Make this
  			 * simple by forcing the entire CMA resv range
  			 * to be in the same zone.
  			 */
  			if (page_zone(pfn_to_page(pfn)) != zone)
  				goto err;
  		}
  		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
  	} while (--i);
  
  	mutex_init(&cma->lock);
  	return 0;
  
  err:
  	kfree(cma->bitmap);

  	cma->count = 0;

  	return -EINVAL;
  }
  
  static int __init cma_init_reserved_areas(void)
  {
  	int i;
  
  	for (i = 0; i < cma_area_count; i++) {
  		int ret = cma_activate_area(&cma_areas[i]);
  
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  core_initcall(cma_init_reserved_areas);
  
  /**

   * cma_init_reserved_mem() - create custom contiguous area from reserved memory
   * @base: Base address of the reserved area
   * @size: Size of the reserved area (in bytes),
   * @order_per_bit: Order of pages represented by one bit on bitmap.
   * @res_cma: Pointer to store the created cma region.
   *
   * This function creates custom contiguous area from already reserved memory.
   */
  int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
  				 int order_per_bit, struct cma **res_cma)
  {
  	struct cma *cma;
  	phys_addr_t alignment;
  
  	/* Sanity checks */
  	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
  		pr_err("Not enough slots for CMA reserved regions!
  ");
  		return -ENOSPC;
  	}
  
  	if (!size || !memblock_is_region_reserved(base, size))
  		return -EINVAL;
  
  	/* ensure minimal alignment requied by mm core */
  	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
  
  	/* alignment should be aligned with order_per_bit */
  	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
  		return -EINVAL;
  
  	if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
  		return -EINVAL;
  
  	/*
  	 * Each reserved area must be initialised later, when more kernel
  	 * subsystems (like slab allocator) are available.
  	 */
  	cma = &cma_areas[cma_area_count];
  	cma->base_pfn = PFN_DOWN(base);
  	cma->count = size >> PAGE_SHIFT;
  	cma->order_per_bit = order_per_bit;
  	*res_cma = cma;
  	cma_area_count++;
  
  	return 0;
  }
  
  /**

   * cma_declare_contiguous() - reserve custom contiguous area

   * @base: Base address of the reserved area optional, use 0 for any

   * @size: Size of the reserved area (in bytes),

   * @limit: End address of the reserved memory (optional, 0 for any).
   * @alignment: Alignment for the CMA area, should be power of 2 or zero
   * @order_per_bit: Order of pages represented by one bit on bitmap.

   * @fixed: hint about where to place the reserved area

   * @res_cma: Pointer to store the created cma region.

   *
   * This function reserves memory from early allocator. It should be
   * called by arch specific code once the early allocator (memblock or bootmem)
   * has been activated and all other subsystems have already allocated/reserved
   * memory. This function allows to create custom reserved areas.
   *
   * If @fixed is true, reserve contiguous area at exactly @base.  If false,
   * reserve in range from @base to @limit.
   */

  int __init cma_declare_contiguous(phys_addr_t base,
  			phys_addr_t size, phys_addr_t limit,

  			phys_addr_t alignment, unsigned int order_per_bit,

  			bool fixed, struct cma **res_cma)

  {

  	phys_addr_t memblock_end = memblock_end_of_DRAM();

  	phys_addr_t highmem_start;

  	int ret = 0;

  #ifdef CONFIG_X86
  	/*
  	 * high_memory isn't direct mapped memory so retrieving its physical
  	 * address isn't appropriate.  But it would be useful to check the
  	 * physical address of the highmem boundary so it's justfiable to get
  	 * the physical address from it.  On x86 there is a validation check for
  	 * this case, so the following workaround is needed to avoid it.
  	 */
  	highmem_start = __pa_nodebug(high_memory);
  #else
  	highmem_start = __pa(high_memory);
  #endif

  	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)
  ",
  		__func__, &size, &base, &limit, &alignment);

  
  	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
  		pr_err("Not enough slots for CMA reserved regions!
  ");
  		return -ENOSPC;
  	}
  
  	if (!size)
  		return -EINVAL;
  
  	if (alignment && !is_power_of_2(alignment))
  		return -EINVAL;
  
  	/*
  	 * Sanitise input arguments.
  	 * Pages both ends in CMA area could be merged into adjacent unmovable
  	 * migratetype page by page allocator's buddy algorithm. In the case,
  	 * you couldn't get a contiguous memory, which is not what we want.
  	 */
  	alignment = max(alignment,
  		(phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
  	base = ALIGN(base, alignment);
  	size = ALIGN(size, alignment);
  	limit &= ~(alignment - 1);

  	if (!base)
  		fixed = false;

  	/* size should be aligned with order_per_bit */
  	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
  		return -EINVAL;

  	/*

  	 * If allocating at a fixed base the request region must not cross the
  	 * low/high memory boundary.

  	 */

  	if (fixed && base < highmem_start && base + size > highmem_start) {

  		ret = -EINVAL;

  		pr_err("Region at %pa defined on low/high memory boundary (%pa)
  ",
  			&base, &highmem_start);

  		goto err;
  	}

  	/*
  	 * If the limit is unspecified or above the memblock end, its effective
  	 * value will be the memblock end. Set it explicitly to simplify further
  	 * checks.
  	 */
  	if (limit == 0 || limit > memblock_end)
  		limit = memblock_end;

  	/* Reserve memory */

  	if (fixed) {

  		if (memblock_is_region_reserved(base, size) ||
  		    memblock_reserve(base, size) < 0) {
  			ret = -EBUSY;
  			goto err;
  		}
  	} else {

  		phys_addr_t addr = 0;
  
  		/*
  		 * All pages in the reserved area must come from the same zone.
  		 * If the requested region crosses the low/high memory boundary,
  		 * try allocating from high memory first and fall back to low
  		 * memory in case of failure.
  		 */
  		if (base < highmem_start && limit > highmem_start) {
  			addr = memblock_alloc_range(size, alignment,
  						    highmem_start, limit);
  			limit = highmem_start;
  		}

  		if (!addr) {

  			addr = memblock_alloc_range(size, alignment, base,
  						    limit);
  			if (!addr) {
  				ret = -ENOMEM;
  				goto err;
  			}

  		}

  		/*
  		 * kmemleak scans/reads tracked objects for pointers to other
  		 * objects but this address isn't mapped and accessible
  		 */
  		kmemleak_ignore(phys_to_virt(addr));

  		base = addr;

  	}

  	ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
  	if (ret)
  		goto err;

  	totalcma_pages += (size / PAGE_SIZE);

  	pr_info("Reserved %ld MiB at %pa
  ", (unsigned long)size / SZ_1M,
  		&base);

  	return 0;
  
  err:

  	pr_err("Failed to reserve %ld MiB
  ", (unsigned long)size / SZ_1M);

  	return ret;
  }
  
  /**
   * cma_alloc() - allocate pages from contiguous area
   * @cma:   Contiguous memory region for which the allocation is performed.
   * @count: Requested number of pages.
   * @align: Requested alignment of pages (in PAGE_SIZE order).
   *
   * This function allocates part of contiguous memory on specific
   * contiguous memory area.
   */
  struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
  {

  	unsigned long mask, offset, pfn, start = 0;

  	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
  	struct page *page = NULL;
  	int ret;
  
  	if (!cma || !cma->count)
  		return NULL;
  
  	pr_debug("%s(cma %p, count %d, align %d)
  ", __func__, (void *)cma,
  		 count, align);
  
  	if (!count)
  		return NULL;
  
  	mask = cma_bitmap_aligned_mask(cma, align);

  	offset = cma_bitmap_aligned_offset(cma, align);

  	bitmap_maxno = cma_bitmap_maxno(cma);
  	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
  
  	for (;;) {
  		mutex_lock(&cma->lock);

  		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
  				bitmap_maxno, start, bitmap_count, mask,
  				offset);

  		if (bitmap_no >= bitmap_maxno) {
  			mutex_unlock(&cma->lock);
  			break;
  		}
  		bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
  		/*
  		 * It's safe to drop the lock here. We've marked this region for
  		 * our exclusive use. If the migration fails we will take the
  		 * lock again and unmark it.
  		 */
  		mutex_unlock(&cma->lock);
  
  		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
  		mutex_lock(&cma_mutex);
  		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
  		mutex_unlock(&cma_mutex);
  		if (ret == 0) {
  			page = pfn_to_page(pfn);
  			break;

  		}

  		cma_clear_bitmap(cma, pfn, count);

  		if (ret != -EBUSY)
  			break;

  		pr_debug("%s(): memory range at %p is busy, retrying
  ",
  			 __func__, pfn_to_page(pfn));
  		/* try again with a bit different memory target */
  		start = bitmap_no + mask + 1;
  	}
  
  	pr_debug("%s(): returned %p
  ", __func__, page);
  	return page;
  }
  
  /**
   * cma_release() - release allocated pages
   * @cma:   Contiguous memory region for which the allocation is performed.
   * @pages: Allocated pages.
   * @count: Number of allocated pages.
   *
   * This function releases memory allocated by alloc_cma().
   * It returns false when provided pages do not belong to contiguous area and
   * true otherwise.
   */
  bool cma_release(struct cma *cma, struct page *pages, int count)
  {
  	unsigned long pfn;
  
  	if (!cma || !pages)
  		return false;
  
  	pr_debug("%s(page %p)
  ", __func__, (void *)pages);
  
  	pfn = page_to_pfn(pages);
  
  	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
  		return false;
  
  	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
  
  	free_contig_range(pfn, count);
  	cma_clear_bitmap(cma, pfn, count);
  
  	return true;
  }