dma-direct: add support for dma_coherent_default_memory
authorChristoph Hellwig <hch@lst.de>
Wed, 23 Jun 2021 12:21:16 +0000 (14:21 +0200)
committerChristoph Hellwig <hch@lst.de>
Wed, 18 Aug 2021 14:24:09 +0000 (16:24 +0200)
Add an option to allocate uncached memory for dma_alloc_coherent from
the global dma_coherent_default_memory.  This will allow to move
arm-nommu (and eventually other platforms) to use generic code for
allocating uncached memory from a pre-populated pool.

Note that this is a different pool from the one that platforms that
can remap at runtime use for GFP_ATOMIC allocations for now, although
there might be opportunities to eventually end up with a common codebase
for the two use cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dillon Min <dillon.minfei@gmail.com>
kernel/dma/Kconfig
kernel/dma/direct.c

index 77b4055..725cfd5 100644 (file)
@@ -93,6 +93,10 @@ config DMA_COHERENT_POOL
        select GENERIC_ALLOCATOR
        bool
 
+config DMA_GLOBAL_POOL
+       select DMA_DECLARE_COHERENT
+       bool
+
 config DMA_REMAP
        bool
        depends on MMU
index f33ceb6..8dca4f9 100644 (file)
@@ -156,9 +156,14 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 
        if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
            !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+           !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
            !dev_is_dma_coherent(dev))
                return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
 
+       if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
+           !dev_is_dma_coherent(dev))
+               return dma_alloc_from_global_coherent(dev, size, dma_handle);
+
        /*
         * Remapping or decrypting memory may block. If either is required and
         * we can't block, allocate the memory from the atomic pools.
@@ -255,11 +260,19 @@ void dma_direct_free(struct device *dev, size_t size,
 
        if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
            !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+           !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
            !dev_is_dma_coherent(dev)) {
                arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
                return;
        }
 
+       if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
+           !dev_is_dma_coherent(dev)) {
+               if (!dma_release_from_global_coherent(page_order, cpu_addr))
+                       WARN_ON_ONCE(1);
+               return;
+       }
+
        /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
        if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
            dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
@@ -462,6 +475,8 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
 
        if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
                return ret;
+       if (dma_mmap_from_global_coherent(vma, cpu_addr, size, &ret))
+               return ret;
 
        if (vma->vm_pgoff >= count || user_count > count - vma->vm_pgoff)
                return -ENXIO;