To facilitate streaming DMA APIs, this patch introduces a set of generic
cache operations related dma sync. Any platform can use the generic ops
to provide platform specific cache management operations. Once the
standard RISC-V CMO extension is available, it can be built on top of it.
Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
---
arch/riscv/include/asm/dma-noncoherent.h | 19 +++++++
arch/riscv/mm/Makefile | 1 +
arch/riscv/mm/dma-noncoherent.c | 66 ++++++++++++++++++++++++
3 files changed, 86 insertions(+)
create mode 100644 arch/riscv/include/asm/dma-noncoherent.h
create mode 100644 arch/riscv/mm/dma-noncoherent.c
diff --git a/arch/riscv/include/asm/dma-noncoherent.h b/arch/riscv/include/asm/dma-noncoherent.h
new file mode 100644
index 000000000000..5bdb03c9c427
--- /dev/null
+++ b/arch/riscv/include/asm/dma-noncoherent.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#ifndef __ASM_RISCV_DMA_NON_COHERENT_H
+#define __ASM_RISCV_DMA_NON_COHERENT_H
+
+#ifdef CONFIG_RISCV_DMA_NONCOHERENT
+struct riscv_dma_cache_sync {
+ void (*cache_invalidate)(phys_addr_t paddr, size_t size);
+ void (*cache_clean)(phys_addr_t paddr, size_t size);
+ void (*cache_flush)(phys_addr_t paddr, size_t size);
+};
+
+void riscv_dma_cache_sync_set(struct riscv_dma_cache_sync *ops);
+#endif
+
+#endif
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index 7ebaef10ea1b..959bef49098b 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -27,3 +27,4 @@ KASAN_SANITIZE_init.o := n
endif
obj-$(CONFIG_DEBUG_VIRTUAL) += physaddr.o
+obj-$(CONFIG_RISCV_DMA_NONCOHERENT) += dma-noncoherent.o
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
new file mode 100644
index 000000000000..2f6e9627c4aa
--- /dev/null
+++ b/arch/riscv/mm/dma-noncoherent.c
@@ -0,0 +1,66 @@
+// 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/init.h>
+#include <linux/io.h>
+#include <linux/libfdt.h>
+#include <linux/mm.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <asm/dma-noncoherent.h>
+
+static struct riscv_dma_cache_sync *dma_cache_sync;
+unsigned long riscv_dma_uc_offset;
+
+static void __dma_sync(phys_addr_t paddr, size_t size, enum dma_data_direction dir)
+{
+ if ((dir == DMA_FROM_DEVICE) && (dma_cache_sync->cache_invalidate))
+ dma_cache_sync->cache_invalidate(paddr, size);
+ else if ((dir == DMA_TO_DEVICE) && (dma_cache_sync->cache_clean))
+ dma_cache_sync->cache_clean(paddr, size);
+ else if ((dir == DMA_BIDIRECTIONAL) && dma_cache_sync->cache_flush)
+ dma_cache_sync->cache_flush(paddr, size);
+}
+
+void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, enum dma_data_direction dir)
+{
+ if (!dma_cache_sync)
+ return;
+
+ __dma_sync(paddr, size, dir);
+}
+
+void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size, enum dma_data_direction dir)
+{
+ if (!dma_cache_sync)
+ return;
+
+ __dma_sync(paddr, size, dir);
+}
+
+void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ const struct iommu_ops *iommu, bool coherent)
+{
+ /* If a specific device is dma-coherent, set it here */
+ dev->dma_coherent = coherent;
+}
+
+void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+ void *flush_addr = page_address(page);
+
+ memset(flush_addr, 0, size);
+ if (dma_cache_sync && dma_cache_sync->cache_flush)
+ dma_cache_sync->cache_flush(__pa(flush_addr), size);
+}
+
+void riscv_dma_cache_sync_set(struct riscv_dma_cache_sync *ops)
+{
+ dma_cache_sync = ops;
+}
--
2.31.1
