dma-mapping: move the arm64 noncoherent alloc/free support to common code

The arm64 codebase to implement coherent dma allocation for architectures
with non-coherent DMA is a good start for a generic implementation, given
that is uses the generic remap helpers, provides the atomic pool for
allocations that can't sleep and still is realtively simple and well
tested.  Move it to kernel/dma and allow architectures to opt into it
using a config symbol.  Architectures just need to provide a new
arch_dma_prep_coherent helper to writeback an invalidate the caches
for any memory that gets remapped for uncached access.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>

2 files changed, 11 insertions, 175 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5d065acb6d10..2e645ea693ea 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -82,7 +82,7 @@ config ARM64
         select CRC32
         select DCACHE_WORD_ACCESS
         select DMA_DIRECT_OPS
-        select DMA_REMAP
+        select DMA_DIRECT_REMAP
         select EDAC_SUPPORT
         select FRAME_POINTER
         select GENERIC_ALLOCATOR
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index a3ac26284845..e2e7e5d0f94e 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -33,113 +33,6 @@
 
 #include <asm/cacheflush.h>
 
-static struct gen_pool *atomic_pool __ro_after_init;
-
-#define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
-static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
-
-static int __init early_coherent_pool(char *p)
-{
-        atomic_pool_size = memparse(p, &p);
-        return 0;
-}
-early_param("coherent_pool", early_coherent_pool);
-
-static void *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
-{
-        unsigned long val;
-        void *ptr = NULL;
-
-        if (!atomic_pool) {
-                WARN(1, "coherent pool not initialised!\n");
-                return NULL;
-        }
-
-        val = gen_pool_alloc(atomic_pool, size);
-        if (val) {
-                phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
-
-                *ret_page = phys_to_page(phys);
-                ptr = (void *)val;
-                memset(ptr, 0, size);
-        }
-
-        return ptr;
-}
-
-static bool __in_atomic_pool(void *start, size_t size)
-{
-        return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
-}
-
-static int __free_from_pool(void *start, size_t size)
-{
-        if (!__in_atomic_pool(start, size))
-                return 0;
-
-        gen_pool_free(atomic_pool, (unsigned long)start, size);
-
-        return 1;
-}
-
-void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
-                gfp_t flags, unsigned long attrs)
-{
-        struct page *page;
-        void *ptr, *coherent_ptr;
-        pgprot_t prot = pgprot_writecombine(PAGE_KERNEL);
-
-        size = PAGE_ALIGN(size);
-
-        if (!gfpflags_allow_blocking(flags)) {
-                struct page *page = NULL;
-                void *addr = __alloc_from_pool(size, &page, flags);
-
-                if (addr)
-                        *dma_handle = phys_to_dma(dev, page_to_phys(page));
-
-                return addr;
-        }
-
-        ptr = dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs);
-        if (!ptr)
-                goto no_mem;
-
-        /* remove any dirty cache lines on the kernel alias */
-        __dma_flush_area(ptr, size);
-
-        /* create a coherent mapping */
-        page = virt_to_page(ptr);
-        coherent_ptr = dma_common_contiguous_remap(page, size, VM_USERMAP,
-                                                   prot, __builtin_return_address(0));
-        if (!coherent_ptr)
-                goto no_map;
-
-        return coherent_ptr;
-
-no_map:
-        dma_direct_free_pages(dev, size, ptr, *dma_handle, attrs);
-no_mem:
-        return NULL;
-}
-
-void arch_dma_free(struct device *dev, size_t size, void *vaddr,
-                dma_addr_t dma_handle, unsigned long attrs)
-{
-        if (!__free_from_pool(vaddr, PAGE_ALIGN(size))) {
-                void *kaddr = phys_to_virt(dma_to_phys(dev, dma_handle));
-
-                vunmap(vaddr);
-                dma_direct_free_pages(dev, size, kaddr, dma_handle, attrs);
-        }
-}
-
-long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
-                dma_addr_t dma_addr)
-{
-        return __phys_to_pfn(dma_to_phys(dev, dma_addr));
-}
-
 pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
                 unsigned long attrs)
 {
@@ -160,6 +53,11 @@ void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
         __dma_unmap_area(phys_to_virt(paddr), size, dir);
 }
 
+void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+        __dma_flush_area(page_address(page), size);
+}
+
 #ifdef CONFIG_IOMMU_DMA
 static int __swiotlb_get_sgtable_page(struct sg_table *sgt,
                                       struct page *page, size_t size)
@@ -191,67 +89,6 @@ static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_IOMMU_DMA */
 
-static int __init atomic_pool_init(void)
-{
-        pgprot_t prot = __pgprot(PROT_NORMAL_NC);
-        unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
-        struct page *page;
-        void *addr;
-        unsigned int pool_size_order = get_order(atomic_pool_size);
-
-        if (dev_get_cma_area(NULL))
-                page = dma_alloc_from_contiguous(NULL, nr_pages,
-                                                 pool_size_order, false);
-        else
-                page = alloc_pages(GFP_DMA32, pool_size_order);
-
-        if (page) {
-                int ret;
-                void *page_addr = page_address(page);
-
-                memset(page_addr, 0, atomic_pool_size);
-                __dma_flush_area(page_addr, atomic_pool_size);
-
-                atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
-                if (!atomic_pool)
-                        goto free_page;
-
-                addr = dma_common_contiguous_remap(page, atomic_pool_size,
-                                        VM_USERMAP, prot, atomic_pool_init);
-
-                if (!addr)
-                        goto destroy_genpool;
-
-                ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
-                                        page_to_phys(page),
-                                        atomic_pool_size, -1);
-                if (ret)
-                        goto remove_mapping;
-
-                gen_pool_set_algo(atomic_pool,
-                                  gen_pool_first_fit_order_align,
-                                  NULL);
-
-                pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
-                        atomic_pool_size / 1024);
-                return 0;
-        }
-        goto out;
-
-remove_mapping:
-        dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
-destroy_genpool:
-        gen_pool_destroy(atomic_pool);
-        atomic_pool = NULL;
-free_page:
-        if (!dma_release_from_contiguous(NULL, page, nr_pages))
-                __free_pages(page, pool_size_order);
-out:
-        pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
-                atomic_pool_size / 1024);
-        return -ENOMEM;
-}
-
 /********************************************
  * The following APIs are for dummy DMA ops *
  ********************************************/
@@ -350,8 +187,7 @@ static int __init arm64_dma_init(void)
                    TAINT_CPU_OUT_OF_SPEC,
                    "ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)",
                    ARCH_DMA_MINALIGN, cache_line_size());
-
-        return atomic_pool_init();
+        return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC));
 }
 arch_initcall(arm64_dma_init);
 
@@ -397,7 +233,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
                         page = alloc_pages(gfp, get_order(size));
                         addr = page ? page_address(page) : NULL;
                 } else {
-                        addr = __alloc_from_pool(size, &page, gfp);
+                        addr = dma_alloc_from_pool(size, &page, gfp);
                 }
                 if (!addr)
                         return NULL;
@@ -407,7 +243,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
                         if (coherent)
                                 __free_pages(page, get_order(size));
                         else
-                                __free_from_pool(addr, size);
+                                dma_free_from_pool(addr, size);
                         addr = NULL;
                 }
         } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
@@ -471,9 +307,9 @@ static void __iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
          *   coherent devices.
          * Hence how dodgy the below logic looks...
          */
-        if (__in_atomic_pool(cpu_addr, size)) {
+        if (dma_in_atomic_pool(cpu_addr, size)) {
                 iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
-                __free_from_pool(cpu_addr, size);
+                dma_free_from_pool(cpu_addr, size);
         } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
                 struct page *page = vmalloc_to_page(cpu_addr);