text: /*
   * SWIOTLB-based DMA API implementation
   *
   * Copyright (C) 2012 ARM Ltd.
   * Author: Catalin Marinas <catalin.marinas@arm.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <linux/gfp.h>
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/genalloc.h>
  #include <linux/dma-mapping.h>
  #include <linux/dma-contiguous.h>
  #include <linux/vmalloc.h>
  #include <linux/swiotlb.h>
  
  #include <asm/cacheflush.h>
  
  struct dma_map_ops *dma_ops;
  EXPORT_SYMBOL(dma_ops);
  
  static pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot,
  				 bool coherent)
  {
  	if (!coherent || dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs))
  		return pgprot_writecombine(prot);
  	return prot;
  }
  
  static struct gen_pool *atomic_pool;
  
  #define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
  static size_t atomic_pool_size = DEFAULT_DMA_COHERENT_POOL_SIZE;
  
  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 *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
  {
  	unsigned long val;
  	void *ptr = NULL;
  
  	if (!atomic_pool) {
  		WARN(1, "coherent pool not initialised!\n");
  		return NULL;
  	}
  
  	val = gen_pool_alloc(atomic_pool, size);
  	if (val) {
  		phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
  
  		*ret_page = phys_to_page(phys);
  		ptr = (void *)val;
  		memset(ptr, 0, size);
  	}
  
  	return ptr;
  }
  
  static bool __in_atomic_pool(void *start, size_t size)
  {
  	return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
  }
  
  static int __free_from_pool(void *start, size_t size)
  {
  	if (!__in_atomic_pool(start, size))
  		return 0;
  
  	gen_pool_free(atomic_pool, (unsigned long)start, size);
  
  	return 1;
  }
  
  static void *__dma_alloc_coherent(struct device *dev, size_t size,
  				  dma_addr_t *dma_handle, gfp_t flags,
  				  struct dma_attrs *attrs)
  {
  	if (dev == NULL) {
  		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
  		return NULL;
  	}
  
  	if (IS_ENABLED(CONFIG_ZONE_DMA) &&
  	    dev->coherent_dma_mask <= DMA_BIT_MASK(32))
  		flags |= GFP_DMA;
  	if (IS_ENABLED(CONFIG_DMA_CMA) && (flags & __GFP_WAIT)) {
  		struct page *page;
  		void *addr;
  
  		page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
  							get_order(size));
  		if (!page)
  			return NULL;
  
  		*dma_handle = phys_to_dma(dev, page_to_phys(page));
  		addr = page_address(page);
  		memset(addr, 0, size);
  		return addr;
  	} else {
  		return swiotlb_alloc_coherent(dev, size, dma_handle, flags);
  	}
  }
  
  static void __dma_free_coherent(struct device *dev, size_t size,
  				void *vaddr, dma_addr_t dma_handle,
  				struct dma_attrs *attrs)
  {
  	bool freed;
  	phys_addr_t paddr = dma_to_phys(dev, dma_handle);
  
  	if (dev == NULL) {
  		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
  		return;
  	}
  
  	freed = dma_release_from_contiguous(dev,
  					phys_to_page(paddr),
  					size >> PAGE_SHIFT);
  	if (!freed)
  		swiotlb_free_coherent(dev, size, vaddr, dma_handle);
  }
  
  static void *__dma_alloc(struct device *dev, size_t size,
  			 dma_addr_t *dma_handle, gfp_t flags,
  			 struct dma_attrs *attrs)
  {
  	struct page *page;
  	void *ptr, *coherent_ptr;
  	bool coherent = is_device_dma_coherent(dev);
  
  	size = PAGE_ALIGN(size);
  
  	if (!coherent && !(flags & __GFP_WAIT)) {
  		struct page *page = NULL;
  		void *addr = __alloc_from_pool(size, &page, flags);
  
  		if (addr)
  			*dma_handle = phys_to_dma(dev, page_to_phys(page));
  
  		return addr;
  	}
  
  	ptr = __dma_alloc_coherent(dev, size, dma_handle, flags, attrs);
  	if (!ptr)
  		goto no_mem;
  
  	/* no need for non-cacheable mapping if coherent */
  	if (coherent)
  		return ptr;
  
  	/* remove any dirty cache lines on the kernel alias */
  	__dma_flush_range(ptr, ptr + size);
  
  	/* create a coherent mapping */
  	page = virt_to_page(ptr);
  	coherent_ptr = dma_common_contiguous_remap(page, size, VM_USERMAP,
  				__get_dma_pgprot(attrs,
  					__pgprot(PROT_NORMAL_NC), false),
  					__builtin_return_address(0));
  	if (!coherent_ptr)
  		goto no_map;
  
  	return coherent_ptr;
  
  no_map:
  	__dma_free_coherent(dev, size, ptr, *dma_handle, attrs);
  no_mem:
  	*dma_handle = DMA_ERROR_CODE;
  	return NULL;
  }
  
  static void __dma_free(struct device *dev, size_t size,
  		       void *vaddr, dma_addr_t dma_handle,
  		       struct dma_attrs *attrs)
  {
  	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
  
  	size = PAGE_ALIGN(size);
  
  	if (!is_device_dma_coherent(dev)) {
  		if (__free_from_pool(vaddr, size))
  			return;
  		vunmap(vaddr);
  	}
  	__dma_free_coherent(dev, size, swiotlb_addr, dma_handle, attrs);
  }
  
  static dma_addr_t __swiotlb_map_page(struct device *dev, struct page *page,
  				     unsigned long offset, size_t size,
  				     enum dma_data_direction dir,
  				     struct dma_attrs *attrs)
  {
  	dma_addr_t dev_addr;
  
  	dev_addr = swiotlb_map_page(dev, page, offset, size, dir, attrs);
  	if (!is_device_dma_coherent(dev))
  		__dma_map_area(phys_to_virt(dma_to_phys(dev, dev_addr)), size, dir);
  
  	return dev_addr;
  }
  
  
  static void __swiotlb_unmap_page(struct device *dev, dma_addr_t dev_addr,
  				 size_t size, enum dma_data_direction dir,
  				 struct dma_attrs *attrs)
  {
  	if (!is_device_dma_coherent(dev))
  		__dma_unmap_area(phys_to_virt(dma_to_phys(dev, dev_addr)), size, dir);
  	swiotlb_unmap_page(dev, dev_addr, size, dir, attrs);
  }
  
  static int __swiotlb_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
  				  int nelems, enum dma_data_direction dir,
  				  struct dma_attrs *attrs)
  {
  	struct scatterlist *sg;
  	int i, ret;
  
  	ret = swiotlb_map_sg_attrs(dev, sgl, nelems, dir, attrs);
  	if (!is_device_dma_coherent(dev))
  		for_each_sg(sgl, sg, ret, i)
  			__dma_map_area(phys_to_virt(dma_to_phys(dev, sg->dma_address)),
  				       sg->length, dir);
  
  	return ret;
  }
  
  static void __swiotlb_unmap_sg_attrs(struct device *dev,
  				     struct scatterlist *sgl, int nelems,
  				     enum dma_data_direction dir,
  				     struct dma_attrs *attrs)
  {
  	struct scatterlist *sg;
  	int i;
  
  	if (!is_device_dma_coherent(dev))
  		for_each_sg(sgl, sg, nelems, i)
  			__dma_unmap_area(phys_to_virt(dma_to_phys(dev, sg->dma_address)),
  					 sg->length, dir);
  	swiotlb_unmap_sg_attrs(dev, sgl, nelems, dir, attrs);
  }
  
  static void __swiotlb_sync_single_for_cpu(struct device *dev,
  					  dma_addr_t dev_addr, size_t size,
  					  enum dma_data_direction dir)
  {
  	if (!is_device_dma_coherent(dev))
  		__dma_unmap_area(phys_to_virt(dma_to_phys(dev, dev_addr)), size, dir);
  	swiotlb_sync_single_for_cpu(dev, dev_addr, size, dir);
  }
  
  static void __swiotlb_sync_single_for_device(struct device *dev,
  					     dma_addr_t dev_addr, size_t size,
  					     enum dma_data_direction dir)
  {
  	swiotlb_sync_single_for_device(dev, dev_addr, size, dir);
  	if (!is_device_dma_coherent(dev))
  		__dma_map_area(phys_to_virt(dma_to_phys(dev, dev_addr)), size, dir);
  }
  
  static void __swiotlb_sync_sg_for_cpu(struct device *dev,
  				      struct scatterlist *sgl, int nelems,
  				      enum dma_data_direction dir)
  {
  	struct scatterlist *sg;
  	int i;
  
  	if (!is_device_dma_coherent(dev))
  		for_each_sg(sgl, sg, nelems, i)
  			__dma_unmap_area(phys_to_virt(dma_to_phys(dev, sg->dma_address)),
  					 sg->length, dir);
  	swiotlb_sync_sg_for_cpu(dev, sgl, nelems, dir);
  }
  
  static void __swiotlb_sync_sg_for_device(struct device *dev,
  					 struct scatterlist *sgl, int nelems,
  					 enum dma_data_direction dir)
  {
  	struct scatterlist *sg;
  	int i;
  
  	swiotlb_sync_sg_for_device(dev, sgl, nelems, dir);
  	if (!is_device_dma_coherent(dev))
  		for_each_sg(sgl, sg, nelems, i)
  			__dma_map_area(phys_to_virt(dma_to_phys(dev, sg->dma_address)),
  				       sg->length, dir);
  }
  
  /* vma->vm_page_prot must be set appropriately before calling this function */
  static int __dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
  			     void *cpu_addr, dma_addr_t dma_addr, size_t size)
  {
  	int ret = -ENXIO;
  	unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >>
  					PAGE_SHIFT;
  	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
  	unsigned long pfn = dma_to_phys(dev, dma_addr) >> PAGE_SHIFT;
  	unsigned long off = vma->vm_pgoff;
  
  	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
  		return ret;
  
  	if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
  		ret = remap_pfn_range(vma, vma->vm_start,
  				      pfn + off,
  				      vma->vm_end - vma->vm_start,
  				      vma->vm_page_prot);
  	}
  
  	return ret;
  }
  
  static int __swiotlb_mmap(struct device *dev,
  			  struct vm_area_struct *vma,
  			  void *cpu_addr, dma_addr_t dma_addr, size_t size,
  			  struct dma_attrs *attrs)
  {
  	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot,
  					     is_device_dma_coherent(dev));
  	return __dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
  }
  
  static struct dma_map_ops swiotlb_dma_ops = {
  	.alloc = __dma_alloc,
  	.free = __dma_free,
  	.mmap = __swiotlb_mmap,
  	.map_page = __swiotlb_map_page,
  	.unmap_page = __swiotlb_unmap_page,
  	.map_sg = __swiotlb_map_sg_attrs,
  	.unmap_sg = __swiotlb_unmap_sg_attrs,
  	.sync_single_for_cpu = __swiotlb_sync_single_for_cpu,
  	.sync_single_for_device = __swiotlb_sync_single_for_device,
  	.sync_sg_for_cpu = __swiotlb_sync_sg_for_cpu,
  	.sync_sg_for_device = __swiotlb_sync_sg_for_device,
  	.dma_supported = swiotlb_dma_supported,
  	.mapping_error = swiotlb_dma_mapping_error,
  };
  
  static int __init atomic_pool_init(void)
  {
  	pgprot_t prot = __pgprot(PROT_NORMAL_NC);
  	unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
  	struct page *page;
  	void *addr;
  	unsigned int pool_size_order = get_order(atomic_pool_size);
  
  	if (dev_get_cma_area(NULL))
  		page = dma_alloc_from_contiguous(NULL, nr_pages,
  							pool_size_order);
  	else
  		page = alloc_pages(GFP_DMA, pool_size_order);
  
  	if (page) {
  		int ret;
  		void *page_addr = page_address(page);
  
  		memset(page_addr, 0, atomic_pool_size);
  		__dma_flush_range(page_addr, page_addr + atomic_pool_size);
  
  		atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
  		if (!atomic_pool)
  			goto free_page;
  
  		addr = dma_common_contiguous_remap(page, atomic_pool_size,
  					VM_USERMAP, prot, atomic_pool_init);
  
  		if (!addr)
  			goto destroy_genpool;
  
  		ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
  					page_to_phys(page),
  					atomic_pool_size, -1);
  		if (ret)
  			goto remove_mapping;
  
  		gen_pool_set_algo(atomic_pool,
  				  gen_pool_first_fit_order_align,
  				  (void *)PAGE_SHIFT);
  
  		pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
  			atomic_pool_size / 1024);
  		return 0;
  	}
  	goto out;
  
  remove_mapping:
  	dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
  destroy_genpool:
  	gen_pool_destroy(atomic_pool);
  	atomic_pool = NULL;
  free_page:
  	if (!dma_release_from_contiguous(NULL, page, nr_pages))
  		__free_pages(page, pool_size_order);
  out:
  	pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
  		atomic_pool_size / 1024);
  	return -ENOMEM;
  }
  
  static int __init arm64_dma_init(void)
  {
  	int ret;
  
  	dma_ops = &swiotlb_dma_ops;
  
  	ret = atomic_pool_init();
  
  	return ret;
  }
  arch_initcall(arm64_dma_init);
  
  #define PREALLOC_DMA_DEBUG_ENTRIES	4096
  
  static int __init dma_debug_do_init(void)
  {
  	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
  	return 0;
  }
  fs_initcall(dma_debug_do_init);
  