arch/c6x/mm/dma-coherent.c

   1 /*
   2  *  Port on Texas Instruments TMS320C6x architecture
   3  *
   4  *  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
   5  *  Author: Aurelien Jacquiot <aurelien.jacquiot@ti.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  DMA uncached mapping support.
  12  *
  13  *  Using code pulled from ARM
  14  *  Copyright (C) 2000-2004 Russell King
  15  *
  16  */
  17 #include <linux/slab.h>
  18 #include <linux/bitmap.h>
  19 #include <linux/bitops.h>
  20 #include <linux/module.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/dma-mapping.h>
  23 #include <linux/memblock.h>
  24
  25 #include <asm/page.h>
  26
  27 /*
  28  * DMA coherent memory management, can be redefined using the memdma=
  29  * kernel command line
  30  */
  31
  32 /* none by default */
  33 static phys_addr_t dma_base;
  34 static u32 dma_size;
  35 static u32 dma_pages;
  36
  37 static unsigned long *dma_bitmap;
  38
  39 /* bitmap lock */
  40 static DEFINE_SPINLOCK(dma_lock);
  41
  42 /*
  43  * Return a DMA coherent and contiguous memory chunk from the DMA memory
  44  */
  45 static inline u32 __alloc_dma_pages(int order)
  46 {
  47         unsigned long flags;
  48         u32 pos;
  49
  50         spin_lock_irqsave(&dma_lock, flags);
  51         pos = bitmap_find_free_region(dma_bitmap, dma_pages, order);
  52         spin_unlock_irqrestore(&dma_lock, flags);
  53
  54         return dma_base + (pos << PAGE_SHIFT);
  55 }
  56
  57 static void __free_dma_pages(u32 addr, int order)
  58 {
  59         unsigned long flags;
  60         u32 pos = (addr - dma_base) >> PAGE_SHIFT;
  61
  62         if (addr < dma_base || (pos + (1 << order)) >= dma_pages) {
  63                 printk(KERN_ERR "%s: freeing outside range.\n", __func__);
  64                 BUG();
  65         }
  66
  67         spin_lock_irqsave(&dma_lock, flags);
  68         bitmap_release_region(dma_bitmap, pos, order);
  69         spin_unlock_irqrestore(&dma_lock, flags);
  70 }
  71
  72 /*
  73  * Allocate DMA coherent memory space and return both the kernel
  74  * virtual and DMA address for that space.
  75  */
  76 void *dma_alloc_coherent(struct device *dev, size_t size,
  77                          dma_addr_t *handle, gfp_t gfp)
  78 {
  79         u32 paddr;
  80         int order;
  81
  82         if (!dma_size || !size)
  83                 return NULL;
  84
  85         order = get_count_order(((size - 1) >> PAGE_SHIFT) + 1);
  86
  87         paddr = __alloc_dma_pages(order);
  88
  89         if (handle)
  90                 *handle = paddr;
  91
  92         if (!paddr)
  93                 return NULL;
  94
  95         return phys_to_virt(paddr);
  96 }
  97 EXPORT_SYMBOL(dma_alloc_coherent);
  98
  99 /*
 100  * Free DMA coherent memory as defined by the above mapping.
 101  */
 102 void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 103                        dma_addr_t dma_handle)
 104 {
 105         int order;
 106
 107         if (!dma_size || !size)
 108                 return;
 109
 110         order = get_count_order(((size - 1) >> PAGE_SHIFT) + 1);
 111
 112         __free_dma_pages(virt_to_phys(vaddr), order);
 113 }
 114 EXPORT_SYMBOL(dma_free_coherent);
 115
 116 /*
 117  * Initialise the coherent DMA memory allocator using the given uncached region.
 118  */
 119 void __init coherent_mem_init(phys_addr_t start, u32 size)
 120 {
 121         phys_addr_t bitmap_phys;
 122
 123         if (!size)
 124                 return;
 125
 126         printk(KERN_INFO
 127                "Coherent memory (DMA) region start=0x%x size=0x%x\n",
 128                start, size);
 129
 130         dma_base = start;
 131         dma_size = size;
 132
 133         /* allocate bitmap */
 134         dma_pages = dma_size >> PAGE_SHIFT;
 135         if (dma_size & (PAGE_SIZE - 1))
 136                 ++dma_pages;
 137
 138         bitmap_phys = memblock_alloc(BITS_TO_LONGS(dma_pages) * sizeof(long),
 139                                      sizeof(long));
 140
 141         dma_bitmap = phys_to_virt(bitmap_phys);
 142         memset(dma_bitmap, 0, dma_pages * PAGE_SIZE);
 143 }