diff options
Diffstat (limited to 'arch/riscv/mm/dma-noncoherent.c')
| -rw-r--r-- | arch/riscv/mm/dma-noncoherent.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c new file mode 100644 index 000000000000..843107f834b2 --- /dev/null +++ b/arch/riscv/mm/dma-noncoherent.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * RISC-V specific functions to support DMA for non-coherent devices + * + * Copyright (c) 2021 Western Digital Corporation or its affiliates. + */ + +#include <linux/dma-direct.h> +#include <linux/dma-map-ops.h> +#include <linux/mm.h> +#include <asm/cacheflush.h> +#include <asm/dma-noncoherent.h> + +static bool noncoherent_supported __ro_after_init; +int dma_cache_alignment __ro_after_init = ARCH_DMA_MINALIGN; +EXPORT_SYMBOL_GPL(dma_cache_alignment); + +static inline void arch_dma_cache_wback(phys_addr_t paddr, size_t size) +{ + void *vaddr = phys_to_virt(paddr); + +#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS + if (unlikely(noncoherent_cache_ops.wback)) { + noncoherent_cache_ops.wback(paddr, size); + return; + } +#endif + ALT_CMO_OP(CLEAN, vaddr, size, riscv_cbom_block_size); +} + +static inline void arch_dma_cache_inv(phys_addr_t paddr, size_t size) +{ + void *vaddr = phys_to_virt(paddr); + +#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS + if (unlikely(noncoherent_cache_ops.inv)) { + noncoherent_cache_ops.inv(paddr, size); + return; + } +#endif + + ALT_CMO_OP(INVAL, vaddr, size, riscv_cbom_block_size); +} + +static inline void arch_dma_cache_wback_inv(phys_addr_t paddr, size_t size) +{ + void *vaddr = phys_to_virt(paddr); + +#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS + if (unlikely(noncoherent_cache_ops.wback_inv)) { + noncoherent_cache_ops.wback_inv(paddr, size); + return; + } +#endif + + ALT_CMO_OP(FLUSH, vaddr, size, riscv_cbom_block_size); +} + +static inline bool arch_sync_dma_clean_before_fromdevice(void) +{ + return true; +} + +static inline bool arch_sync_dma_cpu_needs_post_dma_flush(void) +{ + return true; +} + +void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, + enum dma_data_direction dir) +{ + switch (dir) { + case DMA_TO_DEVICE: + arch_dma_cache_wback(paddr, size); + break; + + case DMA_FROM_DEVICE: + if (!arch_sync_dma_clean_before_fromdevice()) { + arch_dma_cache_inv(paddr, size); + break; + } + fallthrough; + + case DMA_BIDIRECTIONAL: + /* Skip the invalidate here if it's done later */ + if (IS_ENABLED(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) && + arch_sync_dma_cpu_needs_post_dma_flush()) + arch_dma_cache_wback(paddr, size); + else + arch_dma_cache_wback_inv(paddr, size); + break; + + default: + break; + } +} + +void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size, + enum dma_data_direction dir) +{ + switch (dir) { + case DMA_TO_DEVICE: + break; + + case DMA_FROM_DEVICE: + case DMA_BIDIRECTIONAL: + /* FROM_DEVICE invalidate needed if speculative CPU prefetch only */ + if (arch_sync_dma_cpu_needs_post_dma_flush()) + arch_dma_cache_inv(paddr, size); + break; + + default: + break; + } +} + +void arch_dma_prep_coherent(struct page *page, size_t size) +{ + void *flush_addr = page_address(page); + +#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS + if (unlikely(noncoherent_cache_ops.wback_inv)) { + noncoherent_cache_ops.wback_inv(page_to_phys(page), size); + return; + } +#endif + + ALT_CMO_OP(FLUSH, flush_addr, size, riscv_cbom_block_size); +} + +void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, + bool coherent) +{ + WARN_TAINT(!coherent && riscv_cbom_block_size > ARCH_DMA_MINALIGN, + TAINT_CPU_OUT_OF_SPEC, + "%s %s: ARCH_DMA_MINALIGN smaller than riscv,cbom-block-size (%d < %d)", + dev_driver_string(dev), dev_name(dev), + ARCH_DMA_MINALIGN, riscv_cbom_block_size); + + WARN_TAINT(!coherent && !noncoherent_supported, TAINT_CPU_OUT_OF_SPEC, + "%s %s: device non-coherent but no non-coherent operations supported", + dev_driver_string(dev), dev_name(dev)); + + dev->dma_coherent = coherent; +} + +void riscv_noncoherent_supported(void) +{ + WARN(!riscv_cbom_block_size, + "Non-coherent DMA support enabled without a block size\n"); + noncoherent_supported = true; +} + +void __init riscv_set_dma_cache_alignment(void) +{ + if (!noncoherent_supported) + dma_cache_alignment = 1; +} |