arch/mips/sgi-ip32/ip32-dma.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2006  Ralf Baechle <ralf@linux-mips.org>
   4  */
   5 #include <linux/dma-direct.h>
   6 #include <asm/ip32/crime.h>
   7
   8 /*
   9  * Few notes.
  10  * 1. CPU sees memory as two chunks: 0-256M@0x0, and the rest @0x40000000+256M
  11  * 2. PCI sees memory as one big chunk @0x0 (or we could use 0x40000000 for
  12  *    native-endian)
  13  * 3. All other devices see memory as one big chunk at 0x40000000
  14  * 4. Non-PCI devices will pass NULL as struct device*
  15  *
  16  * Thus we translate differently, depending on device.
  17  */
  18
  19 #define RAM_OFFSET_MASK 0x3fffffffUL
  20
  21 dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
  22 {
  23         dma_addr_t dma_addr = paddr & RAM_OFFSET_MASK;
  24
  25         if (!dev)
  26                 dma_addr += CRIME_HI_MEM_BASE;
  27         return dma_addr;
  28 }
  29
  30 phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr)
  31 {
  32         phys_addr_t paddr = dma_addr & RAM_OFFSET_MASK;
  33
  34         if (dma_addr >= 256*1024*1024)
  35                 paddr += CRIME_HI_MEM_BASE;
  36         return paddr;
  37 }