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 */
__alloc_dma_pages(int order)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
__free_dma_pages(u32 addr,int order)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 */
dma_alloc_coherent(struct device * dev,size_t size,dma_addr_t * handle,gfp_t gfp)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 */
dma_free_coherent(struct device * dev,size_t size,void * vaddr,dma_addr_t dma_handle)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 */
coherent_mem_init(phys_addr_t start,u32 size)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 }
144