text: /*
   * DMA implementation for Hexagon
   *
   * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 and
   * only 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, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   */
  
  #include <linux/dma-mapping.h>
  #include <linux/bootmem.h>
  #include <linux/genalloc.h>
  #include <asm/dma-mapping.h>
  #include <linux/module.h>
  #include <asm/page.h>
  
  struct dma_map_ops *dma_ops;
  EXPORT_SYMBOL(dma_ops);
  
  int bad_dma_address;  /*  globals are automatically initialized to zero  */
  
  static inline void *dma_addr_to_virt(dma_addr_t dma_addr)
  {
  	return phys_to_virt((unsigned long) dma_addr);
  }
  
  int dma_supported(struct device *dev, u64 mask)
  {
  	if (mask == DMA_BIT_MASK(32))
  		return 1;
  	else
  		return 0;
  }
  EXPORT_SYMBOL(dma_supported);
  
  int dma_set_mask(struct device *dev, u64 mask)
  {
  	if (!dev->dma_mask || !dma_supported(dev, mask))
  		return -EIO;
  
  	*dev->dma_mask = mask;
  
  	return 0;
  }
  EXPORT_SYMBOL(dma_set_mask);
  
  static struct gen_pool *coherent_pool;
  
  
  /* Allocates from a pool of uncached memory that was reserved at boot time */
  
  static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
  				 dma_addr_t *dma_addr, gfp_t flag,
  				 struct dma_attrs *attrs)
  {
  	void *ret;
  
  	/*
  	 * Our max_low_pfn should have been backed off by 16MB in
  	 * mm/init.c to create DMA coherent space.  Use that as the VA
  	 * for the pool.
  	 */
  
  	if (coherent_pool == NULL) {
  		coherent_pool = gen_pool_create(PAGE_SHIFT, -1);
  
  		if (coherent_pool == NULL)
  			panic("Can't create %s() memory pool!", __func__);
  		else
  			gen_pool_add(coherent_pool,
  				pfn_to_virt(max_low_pfn),
  				hexagon_coherent_pool_size, -1);
  	}
  
  	ret = (void *) gen_pool_alloc(coherent_pool, size);
  
  	if (ret) {
  		memset(ret, 0, size);
  		*dma_addr = (dma_addr_t) virt_to_phys(ret);
  	} else
  		*dma_addr = ~0;
  
  	return ret;
  }
  
  static void hexagon_free_coherent(struct device *dev, size_t size, void *vaddr,
  				  dma_addr_t dma_addr, struct dma_attrs *attrs)
  {
  	gen_pool_free(coherent_pool, (unsigned long) vaddr, size);
  }
  
  static int check_addr(const char *name, struct device *hwdev,
  		      dma_addr_t bus, size_t size)
  {
  	if (hwdev && hwdev->dma_mask && !dma_capable(hwdev, bus, size)) {
  		if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
  			printk(KERN_ERR
  				"%s: overflow %Lx+%zu of device mask %Lx\n",
  				name, (long long)bus, size,
  				(long long)*hwdev->dma_mask);
  		return 0;
  	}
  	return 1;
  }
  
  static int hexagon_map_sg(struct device *hwdev, struct scatterlist *sg,
  			  int nents, enum dma_data_direction dir,
  			  struct dma_attrs *attrs)
  {
  	struct scatterlist *s;
  	int i;
  
  	WARN_ON(nents == 0 || sg[0].length == 0);
  
  	for_each_sg(sg, s, nents, i) {
  		s->dma_address = sg_phys(s);
  		if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  			return 0;
  
  		s->dma_length = s->length;
  
  		flush_dcache_range(dma_addr_to_virt(s->dma_address),
  				   dma_addr_to_virt(s->dma_address + s->length));
  	}
  
  	return nents;
  }
  
  /*
   * address is virtual
   */
  static inline void dma_sync(void *addr, size_t size,
  			    enum dma_data_direction dir)
  {
  	switch (dir) {
  	case DMA_TO_DEVICE:
  		hexagon_clean_dcache_range((unsigned long) addr,
  		(unsigned long) addr + size);
  		break;
  	case DMA_FROM_DEVICE:
  		hexagon_inv_dcache_range((unsigned long) addr,
  		(unsigned long) addr + size);
  		break;
  	case DMA_BIDIRECTIONAL:
  		flush_dcache_range((unsigned long) addr,
  		(unsigned long) addr + size);
  		break;
  	default:
  		BUG();
  	}
  }
  
  /**
   * hexagon_map_page() - maps an address for device DMA
   * @dev:	pointer to DMA device
   * @page:	pointer to page struct of DMA memory
   * @offset:	offset within page
   * @size:	size of memory to map
   * @dir:	transfer direction
   * @attrs:	pointer to DMA attrs (not used)
   *
   * Called to map a memory address to a DMA address prior
   * to accesses to/from device.
   *
   * We don't particularly have many hoops to jump through
   * so far.  Straight translation between phys and virtual.
   *
   * DMA is not cache coherent so sync is necessary; this
   * seems to be a convenient place to do it.
   *
   */
  static dma_addr_t hexagon_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 bus = page_to_phys(page) + offset;
  	WARN_ON(size == 0);
  
  	if (!check_addr("map_single", dev, bus, size))
  		return bad_dma_address;
  
  	dma_sync(dma_addr_to_virt(bus), size, dir);
  
  	return bus;
  }
  
  static void hexagon_sync_single_for_cpu(struct device *dev,
  					dma_addr_t dma_handle, size_t size,
  					enum dma_data_direction dir)
  {
  	dma_sync(dma_addr_to_virt(dma_handle), size, dir);
  }
  
  static void hexagon_sync_single_for_device(struct device *dev,
  					dma_addr_t dma_handle, size_t size,
  					enum dma_data_direction dir)
  {
  	dma_sync(dma_addr_to_virt(dma_handle), size, dir);
  }
  
  struct dma_map_ops hexagon_dma_ops = {
  	.alloc		= hexagon_dma_alloc_coherent,
  	.free		= hexagon_free_coherent,
  	.map_sg		= hexagon_map_sg,
  	.map_page	= hexagon_map_page,
  	.sync_single_for_cpu = hexagon_sync_single_for_cpu,
  	.sync_single_for_device = hexagon_sync_single_for_device,
  	.is_phys	= 1,
  };
  
  void __init hexagon_dma_init(void)
  {
  	if (dma_ops)
  		return;
  
  	dma_ops = &hexagon_dma_ops;
  }
  