linux-kernel - [PATCH 5/7] dma-mapping: add a dma_init_global

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Message-Id: <20210712061704.4162464-6-hch@lst.de>
Date:   Mon, 12 Jul 2021 08:17:02 +0200
From:   Christoph Hellwig <hch@....de>
To:     iommu@...ts.linux-foundation.org,
        Russell King <linux@...linux.org.uk>,
        Brian Cain <bcain@...eaurora.org>
Cc:     Dillon Min <dillon.minfei@...il.com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 5/7] dma-mapping: add a dma_init_global_coherent helper

Add a new helper to initialize the global coherent pool.  This both
cleans up the existing initialization which indirects through the
reserved_mem_ops that are normally only used for struct device, and
also allows using the global pool for non-devicetree architectures.

Signed-off-by: Christoph Hellwig <hch@....de>
Tested-by: Dillon Min <dillon.minfei@...il.com>
---
 include/linux/dma-map-ops.h |  2 +-
 kernel/dma/coherent.c       | 32 ++++++++++++++------------------
 2 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 0d53a96a3d64..7e49bb86a0c0 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -176,7 +176,7 @@ void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
 int dma_release_from_global_coherent(int order, void *vaddr);
 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr,
 		size_t size, int *ret);
-
+int dma_init_global_coherent(phys_addr_t phys_addr, size_t size);
 #else
 static inline int dma_declare_coherent_memory(struct device *dev,
 		phys_addr_t phys_addr, dma_addr_t device_addr, size_t size)
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index ab397ebfd5ad..160d4e246ecb 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -300,6 +300,18 @@ int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
 					vaddr, size, ret);
 }
 
+int dma_init_global_coherent(phys_addr_t phys_addr, size_t size)
+{
+	struct dma_coherent_mem *mem;
+
+	mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true);
+	if (IS_ERR(mem))
+		return PTR_ERR(mem);
+	dma_coherent_default_memory = mem;
+	pr_info("DMA: default coherent area is set\n");
+	return 0;
+}
+
 /*
  * Support for reserved memory regions defined in device tree
  */
@@ -367,26 +379,10 @@ static int __init rmem_dma_setup(struct reserved_mem *rmem)
 
 static int __init dma_init_reserved_memory(void)
 {
-	const struct reserved_mem_ops *ops;
-	int ret;
-
 	if (!dma_reserved_default_memory)
 		return -ENOMEM;
-
-	ops = dma_reserved_default_memory->ops;
-
-	/*
-	 * We rely on rmem_dma_device_init() does not propagate error of
-	 * dma_assign_coherent_memory() for "NULL" device.
-	 */
-	ret = ops->device_init(dma_reserved_default_memory, NULL);
-
-	if (!ret) {
-		dma_coherent_default_memory = dma_reserved_default_memory->priv;
-		pr_info("DMA: default coherent area is set\n");
-	}
-
-	return ret;
+	return dma_init_global_coherent(dma_reserved_default_memory->base,
+					dma_reserved_default_memory->size);
 }
 
 core_initcall(dma_init_reserved_memory);
-- 
2.30.2