tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
15unsigned int riscv_cbom_block_size;
16static bool noncoherent_supported;
17
18void 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
38void 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
55void 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
62void 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
79void riscv_init_cbom_blocksize(void)
80{
81 struct device_node *node;
82 unsigned long cbom_hartid;
83 u32 val, probed_block_size;
84 int ret;
85
86 probed_block_size = 0;
87 for_each_of_cpu_node(node) {
88 unsigned long hartid;
89
90 ret = riscv_of_processor_hartid(node, &hartid);
91 if (ret)
92 continue;
93
94 /* set block-size for cbom extension if available */
95 ret = of_property_read_u32(node, "riscv,cbom-block-size", &val);
96 if (ret)
97 continue;
98
99 if (!probed_block_size) {
100 probed_block_size = val;
101 cbom_hartid = hartid;
102 } else {
103 if (probed_block_size != val)
104 pr_warn("cbom-block-size mismatched between harts %lu and %lu\n",
105 cbom_hartid, hartid);
106 }
107 }
108
109 if (probed_block_size)
110 riscv_cbom_block_size = probed_block_size;
111}
112#endif
113
114void riscv_noncoherent_supported(void)
115{
116 WARN(!riscv_cbom_block_size,
117 "Non-coherent DMA support enabled without a block size\n");
118 noncoherent_supported = true;
119}