arm64: DMA mapping API

This patch adds support for the DMA mapping API. It uses dma_map_ops for
flexibility and it currently supports swiotlb. This patch could be
simplified further if the DMA accesses are coherent (not mandated by the
architecture) or if corresponding hooks are placed in the generic
swiotlb code to deal with cache maintenance.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 79 insertions, 0 deletions

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
new file mode 100644
index 000000000000..5eb244453a5b
--- /dev/null
+++ b/arch/arm64/mm/dma-mapping.c
@@ -0,0 +1,79 @@
+/*
+ * SWIOTLB-based DMA API implementation
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/swiotlb.h>
+
+#include <asm/cacheflush.h>
+
+struct dma_map_ops *dma_ops;
+EXPORT_SYMBOL(dma_ops);
+
+static void *arm64_swiotlb_alloc_coherent(struct device *dev, size_t size,
+                                          dma_addr_t *dma_handle, gfp_t flags,
+                                          struct dma_attrs *attrs)
+{
+        if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
+            dev->coherent_dma_mask <= DMA_BIT_MASK(32))
+                flags |= GFP_DMA32;
+        return swiotlb_alloc_coherent(dev, size, dma_handle, flags);
+}
+
+static void arm64_swiotlb_free_coherent(struct device *dev, size_t size,
+                                        void *vaddr, dma_addr_t dma_handle,
+                                        struct dma_attrs *attrs)
+{
+        swiotlb_free_coherent(dev, size, vaddr, dma_handle);
+}
+
+static struct dma_map_ops arm64_swiotlb_dma_ops = {
+        .alloc = arm64_swiotlb_alloc_coherent,
+        .free = arm64_swiotlb_free_coherent,
+        .map_page = swiotlb_map_page,
+        .unmap_page = swiotlb_unmap_page,
+        .map_sg = swiotlb_map_sg_attrs,
+        .unmap_sg = swiotlb_unmap_sg_attrs,
+        .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
+        .sync_single_for_device = swiotlb_sync_single_for_device,
+        .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
+        .sync_sg_for_device = swiotlb_sync_sg_for_device,
+        .dma_supported = swiotlb_dma_supported,
+        .mapping_error = swiotlb_dma_mapping_error,
+};
+
+void __init swiotlb_init_with_default_size(size_t default_size, int verbose);
+
+void __init arm64_swiotlb_init(size_t max_size)
+{
+        dma_ops = &arm64_swiotlb_dma_ops;
+        swiotlb_init_with_default_size(min((size_t)SZ_64M, max_size), 1);
+}
+
+#define PREALLOC_DMA_DEBUG_ENTRIES      4096
+
+static int __init dma_debug_do_init(void)
+{
+        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
+        return 0;
+}
+fs_initcall(dma_debug_do_init);