arch/hexagon/kernel/dma.c

   1 /*
   2  * DMA implementation for Hexagon
   3  *
   4  * Copyright (c) 2010-2012, 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 #include <asm/page.h>
  27
  28 struct dma_map_ops *dma_ops;
  29 EXPORT_SYMBOL(dma_ops);
  30
  31 int bad_dma_address;  /*  globals are automatically initialized to zero  */
  32
  33 static inline void *dma_addr_to_virt(dma_addr_t dma_addr)
  34 {
  35         return phys_to_virt((unsigned long) dma_addr);
  36 }
  37
  38 int dma_supported(struct device *dev, u64 mask)
  39 {
  40         if (mask == DMA_BIT_MASK(32))
  41                 return 1;
  42         else
  43                 return 0;
  44 }
  45 EXPORT_SYMBOL(dma_supported);
  46
  47 int dma_set_mask(struct device *dev, u64 mask)
  48 {
  49         if (!dev->dma_mask || !dma_supported(dev, mask))
  50                 return -EIO;
  51
  52         *dev->dma_mask = mask;
  53
  54         return 0;
  55 }
  56 EXPORT_SYMBOL(dma_set_mask);
  57
  58 static struct gen_pool *coherent_pool;
  59
  60
  61 /* Allocates from a pool of uncached memory that was reserved at boot time */
  62
  63 static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
  64                                  dma_addr_t *dma_addr, gfp_t flag,
  65                                  struct dma_attrs *attrs)
  66 {
  67         void *ret;
  68
  69         /*
  70          * Our max_low_pfn should have been backed off by 16MB in
  71          * mm/init.c to create DMA coherent space.  Use that as the VA
  72          * for the pool.
  73          */
  74
  75         if (coherent_pool == NULL) {
  76                 coherent_pool = gen_pool_create(PAGE_SHIFT, -1);
  77
  78                 if (coherent_pool == NULL)
  79                         panic("Can't create %s() memory pool!", __func__);
  80                 else
  81                         gen_pool_add(coherent_pool,
  82                                 pfn_to_virt(max_low_pfn),
  83                                 hexagon_coherent_pool_size, -1);
  84         }
  85
  86         ret = (void *) gen_pool_alloc(coherent_pool, size);
  87
  88         if (ret) {
  89                 memset(ret, 0, size);
  90                 *dma_addr = (dma_addr_t) virt_to_phys(ret);
  91         } else
  92                 *dma_addr = ~0;
  93
  94         return ret;
  95 }
  96
  97 static void hexagon_free_coherent(struct device *dev, size_t size, void *vaddr,
  98                                   dma_addr_t dma_addr, struct dma_attrs *attrs)
  99 {
 100         gen_pool_free(coherent_pool, (unsigned long) vaddr, size);
 101 }
 102
 103 static int check_addr(const char *name, struct device *hwdev,
 104                       dma_addr_t bus, size_t size)
 105 {
 106         if (hwdev && hwdev->dma_mask && !dma_capable(hwdev, bus, size)) {
 107                 if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
 108                         printk(KERN_ERR
 109                                 "%s: overflow %Lx+%zu of device mask %Lx\n",
 110                                 name, (long long)bus, size,
 111                                 (long long)*hwdev->dma_mask);
 112                 return 0;
 113         }
 114         return 1;
 115 }
 116
 117 static int hexagon_map_sg(struct device *hwdev, struct scatterlist *sg,
 118                           int nents, enum dma_data_direction dir,
 119                           struct dma_attrs *attrs)
 120 {
 121         struct scatterlist *s;
 122         int i;
 123
 124         WARN_ON(nents == 0 || sg[0].length == 0);
 125
 126         for_each_sg(sg, s, nents, i) {
 127                 s->dma_address = sg_phys(s);
 128                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
 129                         return 0;
 130
 131                 s->dma_length = s->length;
 132
 133                 flush_dcache_range(dma_addr_to_virt(s->dma_address),
 134                                    dma_addr_to_virt(s->dma_address + s->length));
 135         }
 136
 137         return nents;
 138 }
 139
 140 /*
 141  * address is virtual
 142  */
 143 static inline void dma_sync(void *addr, size_t size,
 144                             enum dma_data_direction dir)
 145 {
 146         switch (dir) {
 147         case DMA_TO_DEVICE:
 148                 hexagon_clean_dcache_range((unsigned long) addr,
 149                 (unsigned long) addr + size);
 150                 break;
 151         case DMA_FROM_DEVICE:
 152                 hexagon_inv_dcache_range((unsigned long) addr,
 153                 (unsigned long) addr + size);
 154                 break;
 155         case DMA_BIDIRECTIONAL:
 156                 flush_dcache_range((unsigned long) addr,
 157                 (unsigned long) addr + size);
 158                 break;
 159         default:
 160                 BUG();
 161         }
 162 }
 163
 164 /**
 165  * hexagon_map_page() - maps an address for device DMA
 166  * @dev:        pointer to DMA device
 167  * @page:       pointer to page struct of DMA memory
 168  * @offset:     offset within page
 169  * @size:       size of memory to map
 170  * @dir:        transfer direction
 171  * @attrs:      pointer to DMA attrs (not used)
 172  *
 173  * Called to map a memory address to a DMA address prior
 174  * to accesses to/from device.
 175  *
 176  * We don't particularly have many hoops to jump through
 177  * so far.  Straight translation between phys and virtual.
 178  *
 179  * DMA is not cache coherent so sync is necessary; this
 180  * seems to be a convenient place to do it.
 181  *
 182  */
 183 static dma_addr_t hexagon_map_page(struct device *dev, struct page *page,
 184                                    unsigned long offset, size_t size,
 185                                    enum dma_data_direction dir,
 186                                    struct dma_attrs *attrs)
 187 {
 188         dma_addr_t bus = page_to_phys(page) + offset;
 189         WARN_ON(size == 0);
 190
 191         if (!check_addr("map_single", dev, bus, size))
 192                 return bad_dma_address;
 193
 194         dma_sync(dma_addr_to_virt(bus), size, dir);
 195
 196         return bus;
 197 }
 198
 199 static void hexagon_sync_single_for_cpu(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 static void hexagon_sync_single_for_device(struct device *dev,
 207                                         dma_addr_t dma_handle, size_t size,
 208                                         enum dma_data_direction dir)
 209 {
 210         dma_sync(dma_addr_to_virt(dma_handle), size, dir);
 211 }
 212
 213 struct dma_map_ops hexagon_dma_ops = {
 214         .alloc          = hexagon_dma_alloc_coherent,
 215         .free           = hexagon_free_coherent,
 216         .map_sg         = hexagon_map_sg,
 217         .map_page       = hexagon_map_page,
 218         .sync_single_for_cpu = hexagon_sync_single_for_cpu,
 219         .sync_single_for_device = hexagon_sync_single_for_device,
 220         .is_phys        = 1,
 221 };
 222
 223 void __init hexagon_dma_init(void)
 224 {
 225         if (dma_ops)
 226                 return;
 227
 228         dma_ops = &hexagon_dma_ops;
 229 }