// SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (C) 2012 ARM Ltd.
   * Copyright (C) 2020 Google LLC
   */

  #include <linux/cma.h>

  #include <linux/debugfs.h>

  #include <linux/dma-map-ops.h>

  #include <linux/dma-direct.h>

  #include <linux/init.h>
  #include <linux/genalloc.h>

  #include <linux/set_memory.h>

  #include <linux/slab.h>

  #include <linux/workqueue.h>

  static struct gen_pool *atomic_pool_dma __ro_after_init;

  static unsigned long pool_size_dma;

  static struct gen_pool *atomic_pool_dma32 __ro_after_init;

  static unsigned long pool_size_dma32;

  static struct gen_pool *atomic_pool_kernel __ro_after_init;

  static unsigned long pool_size_kernel;

  /* Size can be defined by the coherent_pool command line */
  static size_t atomic_pool_size;

  
  /* Dynamic background expansion when the atomic pool is near capacity */
  static struct work_struct atomic_pool_work;

  
  static int __init early_coherent_pool(char *p)
  {
  	atomic_pool_size = memparse(p, &p);
  	return 0;
  }
  early_param("coherent_pool", early_coherent_pool);

  static void __init dma_atomic_pool_debugfs_init(void)
  {
  	struct dentry *root;
  
  	root = debugfs_create_dir("dma_pools", NULL);
  	if (IS_ERR_OR_NULL(root))
  		return;
  
  	debugfs_create_ulong("pool_size_dma", 0400, root, &pool_size_dma);
  	debugfs_create_ulong("pool_size_dma32", 0400, root, &pool_size_dma32);
  	debugfs_create_ulong("pool_size_kernel", 0400, root, &pool_size_kernel);
  }
  
  static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
  {
  	if (gfp & __GFP_DMA)
  		pool_size_dma += size;
  	else if (gfp & __GFP_DMA32)
  		pool_size_dma32 += size;
  	else
  		pool_size_kernel += size;
  }

  static bool cma_in_zone(gfp_t gfp)
  {
  	unsigned long size;
  	phys_addr_t end;
  	struct cma *cma;
  
  	cma = dev_get_cma_area(NULL);
  	if (!cma)
  		return false;
  
  	size = cma_get_size(cma);
  	if (!size)
  		return false;
  
  	/* CMA can't cross zone boundaries, see cma_activate_area() */
  	end = cma_get_base(cma) + size - 1;
  	if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
  		return end <= DMA_BIT_MASK(zone_dma_bits);
  	if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
  		return end <= DMA_BIT_MASK(32);
  	return true;
  }

  static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
  			      gfp_t gfp)

  {

  	unsigned int order;

  	struct page *page = NULL;

  	void *addr;

  	int ret = -ENOMEM;
  
  	/* Cannot allocate larger than MAX_ORDER-1 */
  	order = min(get_order(pool_size), MAX_ORDER-1);
  
  	do {
  		pool_size = 1 << (PAGE_SHIFT + order);

  		if (cma_in_zone(gfp))
  			page = dma_alloc_from_contiguous(NULL, 1 << order,
  							 order, false);
  		if (!page)
  			page = alloc_pages(gfp, order);

  	} while (!page && order-- > 0);

  	if (!page)
  		goto out;

  	arch_dma_prep_coherent(page, pool_size);

  #ifdef CONFIG_DMA_DIRECT_REMAP

  	addr = dma_common_contiguous_remap(page, pool_size,

  					   pgprot_dmacoherent(PAGE_KERNEL),
  					   __builtin_return_address(0));
  	if (!addr)

  		goto free_page;

  #else
  	addr = page_to_virt(page);
  #endif
  	/*
  	 * Memory in the atomic DMA pools must be unencrypted, the pools do not

  	 * shrink so no re-encryption occurs in dma_direct_free().

  	 */
  	ret = set_memory_decrypted((unsigned long)page_to_virt(page),
  				   1 << order);
  	if (ret)
  		goto remove_mapping;

  	ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
  				pool_size, NUMA_NO_NODE);

  	if (ret)

  		goto encrypt_mapping;

  	dma_atomic_pool_size_add(gfp, pool_size);

  	return 0;

  encrypt_mapping:
  	ret = set_memory_encrypted((unsigned long)page_to_virt(page),
  				   1 << order);
  	if (WARN_ON_ONCE(ret)) {
  		/* Decrypt succeeded but encrypt failed, purposely leak */
  		goto out;
  	}

  remove_mapping:

  #ifdef CONFIG_DMA_DIRECT_REMAP

  	dma_common_free_remap(addr, pool_size);

  #endif
  free_page: __maybe_unused

  	__free_pages(page, order);

  out:

  	return ret;
  }
  
  static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
  {
  	if (pool && gen_pool_avail(pool) < atomic_pool_size)
  		atomic_pool_expand(pool, gen_pool_size(pool), gfp);
  }
  
  static void atomic_pool_work_fn(struct work_struct *work)
  {
  	if (IS_ENABLED(CONFIG_ZONE_DMA))
  		atomic_pool_resize(atomic_pool_dma,
  				   GFP_KERNEL | GFP_DMA);
  	if (IS_ENABLED(CONFIG_ZONE_DMA32))
  		atomic_pool_resize(atomic_pool_dma32,
  				   GFP_KERNEL | GFP_DMA32);
  	atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
  }
  
  static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
  						      gfp_t gfp)
  {
  	struct gen_pool *pool;
  	int ret;
  
  	pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
  	if (!pool)
  		return NULL;
  
  	gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);
  
  	ret = atomic_pool_expand(pool, pool_size, gfp);
  	if (ret) {
  		gen_pool_destroy(pool);
  		pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation
  ",
  		       pool_size >> 10, &gfp);
  		return NULL;
  	}
  
  	pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations
  ",
  		gen_pool_size(pool) >> 10, &gfp);
  	return pool;

  }

  
  static int __init dma_atomic_pool_init(void)
  {
  	int ret = 0;

  	/*
  	 * If coherent_pool was not used on the command line, default the pool
  	 * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1.
  	 */
  	if (!atomic_pool_size) {

  		unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
  		pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
  		atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);

  	}

  	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
  
  	atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
  						    GFP_KERNEL);
  	if (!atomic_pool_kernel)
  		ret = -ENOMEM;

  	if (IS_ENABLED(CONFIG_ZONE_DMA)) {

  		atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
  						GFP_KERNEL | GFP_DMA);
  		if (!atomic_pool_dma)
  			ret = -ENOMEM;

  	}
  	if (IS_ENABLED(CONFIG_ZONE_DMA32)) {

  		atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
  						GFP_KERNEL | GFP_DMA32);
  		if (!atomic_pool_dma32)
  			ret = -ENOMEM;

  	}

  
  	dma_atomic_pool_debugfs_init();

  	return ret;
  }

  postcore_initcall(dma_atomic_pool_init);

  static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)

  {

  	if (prev == NULL) {
  		if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
  			return atomic_pool_dma32;
  		if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
  			return atomic_pool_dma;
  		return atomic_pool_kernel;
  	}
  	if (prev == atomic_pool_kernel)
  		return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
  	if (prev == atomic_pool_dma32)

  		return atomic_pool_dma;

  	return NULL;

  }

  static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
  		struct gen_pool *pool, void **cpu_addr,
  		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))

  {

  	unsigned long addr;
  	phys_addr_t phys;

  	addr = gen_pool_alloc(pool, size);
  	if (!addr)
  		return NULL;

  	phys = gen_pool_virt_to_phys(pool, addr);
  	if (phys_addr_ok && !phys_addr_ok(dev, phys, size)) {
  		gen_pool_free(pool, addr, size);
  		return NULL;
  	}

  	if (gen_pool_avail(pool) < atomic_pool_size)
  		schedule_work(&atomic_pool_work);

  	*cpu_addr = (void *)addr;
  	memset(*cpu_addr, 0, size);
  	return pfn_to_page(__phys_to_pfn(phys));

  }

  struct page *dma_alloc_from_pool(struct device *dev, size_t size,
  		void **cpu_addr, gfp_t gfp,
  		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))

  {

  	struct gen_pool *pool = NULL;

  	struct page *page;

  	while ((pool = dma_guess_pool(pool, gfp))) {
  		page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
  					     phys_addr_ok);
  		if (page)
  			return page;

  	}

  	WARN(1, "Failed to get suitable pool for %s
  ", dev_name(dev));
  	return NULL;

  }

  bool dma_free_from_pool(struct device *dev, void *start, size_t size)

  {

  	struct gen_pool *pool = NULL;

  	while ((pool = dma_guess_pool(pool, 0))) {
  		if (!gen_pool_has_addr(pool, (unsigned long)start, size))
  			continue;
  		gen_pool_free(pool, (unsigned long)start, size);
  		return true;

  	}

  
  	return false;

  }