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 <linux/of.h>
  12 #include <linux/of_device.h>
  13 #include <asm/cacheflush.h>
  14
  15 static unsigned int riscv_cbom_block_size = L1_CACHE_BYTES;
  16 static bool noncoherent_supported;
  17
  18 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
  19                               enum dma_data_direction dir)
  20 {
  21         void *vaddr = phys_to_virt(paddr);
  22
  23         switch (dir) {
  24         case DMA_TO_DEVICE:
  25                 ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
  26                 break;
  27         case DMA_FROM_DEVICE:
  28                 ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
  29                 break;
  30         case DMA_BIDIRECTIONAL:
  31                 ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
  32                 break;
  33         default:
  34                 break;
  35         }
  36 }
  37
  38 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
  39                            enum dma_data_direction dir)
  40 {
  41         void *vaddr = phys_to_virt(paddr);
  42
  43         switch (dir) {
  44         case DMA_TO_DEVICE:
  45                 break;
  46         case DMA_FROM_DEVICE:
  47         case DMA_BIDIRECTIONAL:
  48                 ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
  49                 break;
  50         default:
  51                 break;
  52         }
  53 }
  54
  55 void arch_dma_prep_coherent(struct page *page, size_t size)
  56 {
  57         void *flush_addr = page_address(page);
  58
  59         ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
  60 }
  61
  62 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
  63                 const struct iommu_ops *iommu, bool coherent)
  64 {
  65         WARN_TAINT(!coherent && riscv_cbom_block_size > ARCH_DMA_MINALIGN,
  66                    TAINT_CPU_OUT_OF_SPEC,
  67                    "%s %s: ARCH_DMA_MINALIGN smaller than riscv,cbom-block-size (%d < %d)",
  68                    dev_driver_string(dev), dev_name(dev),
  69                    ARCH_DMA_MINALIGN, riscv_cbom_block_size);
  70
  71         WARN_TAINT(!coherent && !noncoherent_supported, TAINT_CPU_OUT_OF_SPEC,
  72                    "%s %s: device non-coherent but no non-coherent operations supported",
  73                    dev_driver_string(dev), dev_name(dev));
  74
  75         dev->dma_coherent = coherent;
  76 }
  77
  78 #ifdef CONFIG_RISCV_ISA_ZICBOM
  79 void riscv_init_cbom_blocksize(void)
  80 {
  81         struct device_node *node;
  82         int ret;
  83         u32 val;
  84
  85         for_each_of_cpu_node(node) {
  86                 unsigned long hartid;
  87                 int cbom_hartid;
  88
  89                 ret = riscv_of_processor_hartid(node, &hartid);
  90                 if (ret)
  91                         continue;
  92
  93                 if (hartid < 0)
  94                         continue;
  95
  96                 /* set block-size for cbom extension if available */
  97                 ret = of_property_read_u32(node, "riscv,cbom-block-size", &val);
  98                 if (ret)
  99                         continue;
 100
 101                 if (!riscv_cbom_block_size) {
 102                         riscv_cbom_block_size = val;
 103                         cbom_hartid = hartid;
 104                 } else {
 105                         if (riscv_cbom_block_size != val)
 106                                 pr_warn("cbom-block-size mismatched between harts %d and %lu\n",
 107                                         cbom_hartid, hartid);
 108                 }
 109         }
 110 }
 111 #endif
 112
 113 void riscv_noncoherent_supported(void)
 114 {
 115         noncoherent_supported = true;
 116 }