arch/mips/bcm3384/dma.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2014 Kevin Cernekee <cernekee@gmail.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/dma-direction.h>
  11 #include <linux/dma-mapping.h>
  12 #include <linux/init.h>
  13 #include <linux/mm.h>
  14 #include <linux/of.h>
  15 #include <linux/pci.h>
  16 #include <linux/types.h>
  17 #include <dma-coherence.h>
  18
  19 /*
  20  * BCM3384 has configurable address translation windows which allow the
  21  * peripherals' DMA addresses to be different from the Zephyr-visible
  22  * physical addresses.  e.g. usb_dma_addr = zephyr_pa ^ 0x08000000
  23  *
  24  * If our DT "memory" node has a "dma-xor-mask" property we will enable this
  25  * translation using the provided offset.
  26  */
  27 static u32 bcm3384_dma_xor_mask;
  28 static u32 bcm3384_dma_xor_limit = 0xffffffff;
  29
  30 /*
  31  * PCI collapses the memory hole at 0x10000000 - 0x1fffffff.
  32  * On systems with a dma-xor-mask, this range is guaranteed to live above
  33  * the dma-xor-limit.
  34  */
  35 #define BCM3384_MEM_HOLE_PA     0x10000000
  36 #define BCM3384_MEM_HOLE_SIZE   0x10000000
  37
  38 static dma_addr_t bcm3384_phys_to_dma(struct device *dev, phys_addr_t pa)
  39 {
  40         if (dev && dev_is_pci(dev) &&
  41             pa >= (BCM3384_MEM_HOLE_PA + BCM3384_MEM_HOLE_SIZE))
  42                 return pa - BCM3384_MEM_HOLE_SIZE;
  43         if (pa <= bcm3384_dma_xor_limit)
  44                 return pa ^ bcm3384_dma_xor_mask;
  45         return pa;
  46 }
  47
  48 dma_addr_t plat_map_dma_mem(struct device *dev, void *addr, size_t size)
  49 {
  50         return bcm3384_phys_to_dma(dev, virt_to_phys(addr));
  51 }
  52
  53 dma_addr_t plat_map_dma_mem_page(struct device *dev, struct page *page)
  54 {
  55         return bcm3384_phys_to_dma(dev, page_to_phys(page));
  56 }
  57
  58 unsigned long plat_dma_addr_to_phys(struct device *dev, dma_addr_t dma_addr)
  59 {
  60         if (dev && dev_is_pci(dev) &&
  61             dma_addr >= BCM3384_MEM_HOLE_PA)
  62                 return dma_addr + BCM3384_MEM_HOLE_SIZE;
  63         if ((dma_addr ^ bcm3384_dma_xor_mask) <= bcm3384_dma_xor_limit)
  64                 return dma_addr ^ bcm3384_dma_xor_mask;
  65         return dma_addr;
  66 }
  67
  68 static int __init bcm3384_init_dma_xor(void)
  69 {
  70         struct device_node *np = of_find_node_by_type(NULL, "memory");
  71
  72         if (!np)
  73                 return 0;
  74
  75         of_property_read_u32(np, "dma-xor-mask", &bcm3384_dma_xor_mask);
  76         of_property_read_u32(np, "dma-xor-limit", &bcm3384_dma_xor_limit);
  77
  78         of_node_put(np);
  79         return 0;
  80 }
  81 arch_initcall(bcm3384_init_dma_xor);