[PATCH v2 09/29] RISC-V: dma: support multiple dma_alloc_coherent backends

[Ahmad Fatoum]

StarFive JH7100 is incoherent between CPU and dma masters like GMAC.
It has an uncached alias though similar to what we have on MIPS.

StarFive JH7110 will fix this and be cache coherent like other SiFive
SoCs. Support both by allowing driver to define their own
dma_alloc_coherent implementations.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/riscv/cpu/Makefile      |  1 +
 arch/riscv/cpu/dma.c         | 74 ++++++++++++++++++++++++++++++++++++
 arch/riscv/include/asm/dma.h | 48 +++++++----------------
 3 files changed, 88 insertions(+), 35 deletions(-)
 create mode 100644 arch/riscv/cpu/dma.c

diff --git a/arch/riscv/cpu/Makefile b/arch/riscv/cpu/Makefile
index f1312be699a1..9ce77ad869cd 100644
--- a/arch/riscv/cpu/Makefile
+++ b/arch/riscv/cpu/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-y += core.o time.o
+obj-$(CONFIG_HAS_DMA) += dma.o
diff --git a/arch/riscv/cpu/dma.c b/arch/riscv/cpu/dma.c
new file mode 100644
index 000000000000..5a4d714e5e71
--- /dev/null
+++ b/arch/riscv/cpu/dma.c
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <common.h>
+#include <xfuncs.h>
+#include <asm/dma.h>
+#include <malloc.h>
+
+static void __dma_flush_range(dma_addr_t start, dma_addr_t end)
+{
+}
+
+static void *__dma_alloc_coherent(size_t size, dma_addr_t *dma_handle)
+{
+	void *ret;
+
+	ret = xmemalign(PAGE_SIZE, size);
+
+	memset(ret, 0, size);
+
+	if (dma_handle)
+		*dma_handle = (dma_addr_t)ret;
+
+	return ret;
+}
+
+static void __dma_free_coherent(void *vaddr, dma_addr_t dma_handle, size_t size)
+{
+	free(vaddr);
+}
+
+static const struct dma_ops coherent_dma_ops = {
+	.alloc_coherent = __dma_alloc_coherent,
+	.free_coherent = __dma_free_coherent,
+	.flush_range = __dma_flush_range,
+	.inv_range = __dma_flush_range,
+};
+
+static const struct dma_ops *dma_ops = &coherent_dma_ops;
+
+void *dma_alloc_coherent(size_t size, dma_addr_t *dma_handle)
+{
+	return dma_ops->alloc_coherent(size, dma_handle);
+}
+
+void dma_free_coherent(void *vaddr, dma_addr_t dma_handle, size_t size)
+{
+	dma_ops->free_coherent(vaddr, dma_handle, size);
+}
+
+void dma_set_ops(const struct dma_ops *ops)
+{
+	dma_ops = ops;
+}
+
+void dma_sync_single_for_cpu(dma_addr_t address, size_t size, enum dma_data_direction dir)
+{
+        /*
+         * FIXME: This function needs a device argument to support non 1:1 mappings
+         */
+        if (dir != DMA_TO_DEVICE)
+                dma_ops->inv_range(address, address + size);
+}
+
+void dma_sync_single_for_device(dma_addr_t address, size_t size, enum dma_data_direction dir)
+{
+        /*
+         * FIXME: This function needs a device argument to support non 1:1 mappings
+         */
+
+        if (dir == DMA_FROM_DEVICE)
+                dma_ops->inv_range(address, address + size);
+        else
+                dma_ops->flush_range(address, address + size);
+}
diff --git a/arch/riscv/include/asm/dma.h b/arch/riscv/include/asm/dma.h
index 4204653984a3..56bcf06cc4af 100644
--- a/arch/riscv/include/asm/dma.h
+++ b/arch/riscv/include/asm/dma.h
@@ -1,44 +1,22 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_DMA_MAPPING_H
-#define _ASM_DMA_MAPPING_H
+#ifndef _RISCV_ASM_DMA_H
+#define _RISCV_ASM_DMA_H
 
-#include <common.h>
-#include <xfuncs.h>
-#include <linux/build_bug.h>
-#include <malloc.h>
+#include <linux/types.h>
 
-#ifdef CONFIG_MMU
-#error DMA stubs need be replaced when using MMU and caches
-#endif
+struct dma_ops {
+	void *(*alloc_coherent)(size_t size, dma_addr_t *dma_handle);
+	void (*free_coherent)(void *vaddr, dma_addr_t dma_handle, size_t size);
 
-static inline void *dma_alloc_coherent(size_t size, dma_addr_t *dma_handle)
-{
-	void *ret;
+	void (*flush_range)(dma_addr_t start, dma_addr_t end);
+	void (*inv_range)(dma_addr_t start, dma_addr_t end);
+};
 
-	ret = xmemalign(PAGE_SIZE, size);
+/* Override for SoCs with cache-incoherent DMA masters */
+void dma_set_ops(const struct dma_ops *ops);
 
-	memset(ret, 0, size);
+#define DMA_ALIGNMENT 64
 
-	if (dma_handle)
-		*dma_handle = (dma_addr_t)ret;
-
-	return ret;
-}
-
-static inline void dma_free_coherent(void *vaddr, dma_addr_t dma_handle,
-				     size_t size)
-{
-	free(vaddr);
-}
-
-static inline void dma_sync_single_for_cpu(dma_addr_t address, size_t size,
-					   enum dma_data_direction dir)
-{
-}
-
-static inline void dma_sync_single_for_device(dma_addr_t address, size_t size,
-					      enum dma_data_direction dir)
-{
-}
+#include <dma.h>
 
 #endif /* _ASM_DMA_MAPPING_H */
-- 
2.29.2