arch/hexagon/kernel/dma.c

   1 /*
   2  * DMA implementation for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/dma-mapping.h>
  22 #include <linux/bootmem.h>
  23 #include <linux/genalloc.h>
  24 #include <asm/dma-mapping.h>
  25 #include <linux/module.h>
  26
  27 struct dma_map_ops *dma_ops;
  28 EXPORT_SYMBOL(dma_ops);
  29
  30 int bad_dma_address;  /*  globals are automatically initialized to zero  */
  31
  32 int dma_supported(struct device *dev, u64 mask)
  33 {
  34         if (mask == DMA_BIT_MASK(32))
  35                 return 1;
  36         else
  37                 return 0;
  38 }
  39 EXPORT_SYMBOL(dma_supported);
  40
  41 int dma_set_mask(struct device *dev, u64 mask)
  42 {
  43         if (!dev->dma_mask || !dma_supported(dev, mask))
  44                 return -EIO;
  45
  46         *dev->dma_mask = mask;
  47
  48         return 0;
  49 }
  50 EXPORT_SYMBOL(dma_set_mask);
  51
  52 static struct gen_pool *coherent_pool;
  53
  54
  55 /* Allocates from a pool of uncached memory that was reserved at boot time */
  56
  57 static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
  58                                  dma_addr_t *dma_addr, gfp_t flag,
  59                                  struct dma_attrs *attrs)
  60 {
  61         void *ret;
  62
  63         if (coherent_pool == NULL) {
  64                 coherent_pool = gen_pool_create(PAGE_SHIFT, -1);
  65
  66                 if (coherent_pool == NULL)
  67                         panic("Can't create %s() memory pool!", __func__);
  68                 else
  69                         gen_pool_add(coherent_pool,
  70                                 (PAGE_OFFSET + (max_low_pfn << PAGE_SHIFT)),
  71                                 hexagon_coherent_pool_size, -1);
  72         }
  73
  74         ret = (void *) gen_pool_alloc(coherent_pool, size);
  75
  76         if (ret) {
  77                 memset(ret, 0, size);
  78                 *dma_addr = (dma_addr_t) (ret - PAGE_OFFSET);
  79         } else
  80                 *dma_addr = ~0;
  81
  82         return ret;
  83 }
  84
  85 static void hexagon_free_coherent(struct device *dev, size_t size, void *vaddr,
  86                                   dma_addr_t dma_addr, struct dma_attrs *attrs)
  87 {
  88         gen_pool_free(coherent_pool, (unsigned long) vaddr, size);
  89 }
  90
  91 static int check_addr(const char *name, struct device *hwdev,
  92                       dma_addr_t bus, size_t size)
  93 {
  94         if (hwdev && hwdev->dma_mask && !dma_capable(hwdev, bus, size)) {
  95                 if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
  96                         printk(KERN_ERR
  97                                 "%s: overflow %Lx+%zu of device mask %Lx\n",
  98                                 name, (long long)bus, size,
  99                                 (long long)*hwdev->dma_mask);
 100                 return 0;
 101         }
 102         return 1;
 103 }
 104
 105 static int hexagon_map_sg(struct device *hwdev, struct scatterlist *sg,
 106                           int nents, enum dma_data_direction dir,
 107                           struct dma_attrs *attrs)
 108 {
 109         struct scatterlist *s;
 110         int i;
 111
 112         WARN_ON(nents == 0 || sg[0].length == 0);
 113
 114         for_each_sg(sg, s, nents, i) {
 115                 s->dma_address = sg_phys(s);
 116                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
 117                         return 0;
 118
 119                 s->dma_length = s->length;
 120
 121                 flush_dcache_range(PAGE_OFFSET + s->dma_address,
 122                                    PAGE_OFFSET + s->dma_address + s->length);
 123         }
 124
 125         return nents;
 126 }
 127
 128 /*
 129  * address is virtual
 130  */
 131 static inline void dma_sync(void *addr, size_t size,
 132                             enum dma_data_direction dir)
 133 {
 134         switch (dir) {
 135         case DMA_TO_DEVICE:
 136                 hexagon_clean_dcache_range((unsigned long) addr,
 137                 (unsigned long) addr + size);
 138                 break;
 139         case DMA_FROM_DEVICE:
 140                 hexagon_inv_dcache_range((unsigned long) addr,
 141                 (unsigned long) addr + size);
 142                 break;
 143         case DMA_BIDIRECTIONAL:
 144                 flush_dcache_range((unsigned long) addr,
 145                 (unsigned long) addr + size);
 146                 break;
 147         default:
 148                 BUG();
 149         }
 150 }
 151
 152 static inline void *dma_addr_to_virt(dma_addr_t dma_addr)
 153 {
 154         return phys_to_virt((unsigned long) dma_addr);
 155 }
 156
 157 /**
 158  * hexagon_map_page() - maps an address for device DMA
 159  * @dev:        pointer to DMA device
 160  * @page:       pointer to page struct of DMA memory
 161  * @offset:     offset within page
 162  * @size:       size of memory to map
 163  * @dir:        transfer direction
 164  * @attrs:      pointer to DMA attrs (not used)
 165  *
 166  * Called to map a memory address to a DMA address prior
 167  * to accesses to/from device.
 168  *
 169  * We don't particularly have many hoops to jump through
 170  * so far.  Straight translation between phys and virtual.
 171  *
 172  * DMA is not cache coherent so sync is necessary; this
 173  * seems to be a convenient place to do it.
 174  *
 175  */
 176 static dma_addr_t hexagon_map_page(struct device *dev, struct page *page,
 177                                    unsigned long offset, size_t size,
 178                                    enum dma_data_direction dir,
 179                                    struct dma_attrs *attrs)
 180 {
 181         dma_addr_t bus = page_to_phys(page) + offset;
 182         WARN_ON(size == 0);
 183
 184         if (!check_addr("map_single", dev, bus, size))
 185                 return bad_dma_address;
 186
 187         dma_sync(dma_addr_to_virt(bus), size, dir);
 188
 189         return bus;
 190 }
 191
 192 static void hexagon_sync_single_for_cpu(struct device *dev,
 193                                         dma_addr_t dma_handle, size_t size,
 194                                         enum dma_data_direction dir)
 195 {
 196         dma_sync(dma_addr_to_virt(dma_handle), size, dir);
 197 }
 198
 199 static void hexagon_sync_single_for_device(struct device *dev,
 200                                         dma_addr_t dma_handle, size_t size,
 201                                         enum dma_data_direction dir)
 202 {
 203         dma_sync(dma_addr_to_virt(dma_handle), size, dir);
 204 }
 205
 206 struct dma_map_ops hexagon_dma_ops = {
 207         .alloc          = hexagon_dma_alloc_coherent,
 208         .free           = hexagon_free_coherent,
 209         .map_sg         = hexagon_map_sg,
 210         .map_page       = hexagon_map_page,
 211         .sync_single_for_cpu = hexagon_sync_single_for_cpu,
 212         .sync_single_for_device = hexagon_sync_single_for_device,
 213         .is_phys        = 1,
 214 };
 215
 216 void __init hexagon_dma_init(void)
 217 {
 218         if (dma_ops)
 219                 return;
 220
 221         dma_ops = &hexagon_dma_ops;
 222 }