arch/riscv/mm/dma-noncoherent.c

Source file repositories/reference/linux-study-clean/arch/riscv/mm/dma-noncoherent.c

File Facts

System
Linux kernel
Corpus path
arch/riscv/mm/dma-noncoherent.c
Extension
.c
Size
3820 bytes
Lines
158
Domain
Architecture Layer
Bucket
arch/riscv
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

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, 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_assign_dma_coherent(dev, 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;
}

Annotation

Implementation Notes