arch/riscv/mm/dma-noncoherent.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * RISC-V specific functions to support DMA for non-coherent devices
   4  *
   5  * Copyright (c) 2021 Western Digital Corporation or its affiliates.
   6  */
   7
   8 #include <linux/dma-direct.h>
   9 #include <linux/dma-map-ops.h>
  10 #include <linux/mm.h>
  11 #include <asm/cacheflush.h>
  12
  13 static bool noncoherent_supported __ro_after_init;
  14
  15 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
  16                               enum dma_data_direction dir)
  17 {
  18         void *vaddr = phys_to_virt(paddr);
  19
  20         switch (dir) {
  21         case DMA_TO_DEVICE:
  22                 ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
  23                 break;
  24         case DMA_FROM_DEVICE:
  25                 ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
  26                 break;
  27         case DMA_BIDIRECTIONAL:
  28                 ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
  29                 break;
  30         default:
  31                 break;
  32         }
  33 }
  34
  35 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
  36                            enum dma_data_direction dir)
  37 {
  38         void *vaddr = phys_to_virt(paddr);
  39
  40         switch (dir) {
  41         case DMA_TO_DEVICE:
  42                 break;
  43         case DMA_FROM_DEVICE:
  44         case DMA_BIDIRECTIONAL:
  45                 ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
  46                 break;
  47         default:
  48                 break;
  49         }
  50 }
  51
  52 void arch_dma_prep_coherent(struct page *page, size_t size)
  53 {
  54         void *flush_addr = page_address(page);
  55
  56         ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
  57 }
  58
  59 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
  60                 const struct iommu_ops *iommu, bool coherent)
  61 {
  62         WARN_TAINT(!coherent && riscv_cbom_block_size > ARCH_DMA_MINALIGN,
  63                    TAINT_CPU_OUT_OF_SPEC,
  64                    "%s %s: ARCH_DMA_MINALIGN smaller than riscv,cbom-block-size (%d < %d)",
  65                    dev_driver_string(dev), dev_name(dev),
  66                    ARCH_DMA_MINALIGN, riscv_cbom_block_size);
  67
  68         WARN_TAINT(!coherent && !noncoherent_supported, TAINT_CPU_OUT_OF_SPEC,
  69                    "%s %s: device non-coherent but no non-coherent operations supported",
  70                    dev_driver_string(dev), dev_name(dev));
  71
  72         dev->dma_coherent = coherent;
  73 }
  74
  75 void riscv_noncoherent_supported(void)
  76 {
  77         WARN(!riscv_cbom_block_size,
  78              "Non-coherent DMA support enabled without a block size\n");
  79         noncoherent_supported = true;
  80 }