1 files changed, 413 insertions, 0 deletions
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
new file mode 100644
index 000000000..49aaad393
--- /dev/null
+++ b/kernel/dma/coherent.c
@@ -0,0 +1,413 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Coherent per-device memory handling.
+ * Borrowed from i386
+ */
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-map-ops.h>
+
+struct dma_coherent_mem {
+	void		*virt_base;
+	dma_addr_t	device_base;
+	unsigned long	pfn_base;
+	int		size;
+	unsigned long	*bitmap;
+	spinlock_t	spinlock;
+	bool		use_dev_dma_pfn_offset;
+};
+
+static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
+
+static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
+{
+	if (dev && dev->dma_mem)
+		return dev->dma_mem;
+	return NULL;
+}
+
+static inline dma_addr_t dma_get_device_base(struct device *dev,
+					     struct dma_coherent_mem * mem)
+{
+	if (mem->use_dev_dma_pfn_offset)
+		return phys_to_dma(dev, PFN_PHYS(mem->pfn_base));
+	return mem->device_base;
+}
+
+static int dma_init_coherent_memory(phys_addr_t phys_addr,
+		dma_addr_t device_addr, size_t size,
+		struct dma_coherent_mem **mem)
+{
+	struct dma_coherent_mem *dma_mem = NULL;
+	void *mem_base = NULL;
+	int pages = size >> PAGE_SHIFT;
+	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
+	int ret;
+
+	if (!size) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
+	if (!mem_base) {
+		ret = -EINVAL;
+		goto out;
+	}
+	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
+	if (!dma_mem) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!dma_mem->bitmap) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dma_mem->virt_base = mem_base;
+	dma_mem->device_base = device_addr;
+	dma_mem->pfn_base = PFN_DOWN(phys_addr);
+	dma_mem->size = pages;
+	spin_lock_init(&dma_mem->spinlock);
+
+	*mem = dma_mem;
+	return 0;
+
+out:
+	kfree(dma_mem);
+	if (mem_base)
+		memunmap(mem_base);
+	return ret;
+}
+
+static void _dma_release_coherent_memory(struct dma_coherent_mem *mem)
+{
+	if (!mem)
+		return;
+
+	memunmap(mem->virt_base);
+	kfree(mem->bitmap);
+	kfree(mem);
+}
+
+static int dma_assign_coherent_memory(struct device *dev,
+				      struct dma_coherent_mem *mem)
+{
+	if (!dev)
+		return -ENODEV;
+
+	if (dev->dma_mem)
+		return -EBUSY;
+
+	dev->dma_mem = mem;
+	return 0;
+}
+
+/*
+ * Declare a region of memory to be handed out by dma_alloc_coherent() when it
+ * is asked for coherent memory for this device.  This shall only be used
+ * from platform code, usually based on the device tree description.
+ * 
+ * phys_addr is the CPU physical address to which the memory is currently
+ * assigned (this will be ioremapped so the CPU can access the region).
+ *
+ * device_addr is the DMA address the device needs to be programmed with to
+ * actually address this memory (this will be handed out as the dma_addr_t in
+ * dma_alloc_coherent()).
+ *
+ * size is the size of the area (must be a multiple of PAGE_SIZE).
+ *
+ * As a simplification for the platforms, only *one* such region of memory may
+ * be declared per device.
+ */
+int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
+				dma_addr_t device_addr, size_t size)
+{
+	struct dma_coherent_mem *mem;
+	int ret;
+
+	ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
+	if (ret)
+		return ret;
+
+	ret = dma_assign_coherent_memory(dev, mem);
+	if (ret)
+		_dma_release_coherent_memory(mem);
+	return ret;
+}
+
+void dma_release_coherent_memory(struct device *dev)
+{
+	if (dev) {
+		_dma_release_coherent_memory(dev->dma_mem);
+		dev->dma_mem = NULL;
+	}
+}
+
+static void *__dma_alloc_from_coherent(struct device *dev,
+				       struct dma_coherent_mem *mem,
+				       ssize_t size, dma_addr_t *dma_handle)
+{
+	int order = get_order(size);
+	unsigned long flags;
+	int pageno;
+	void *ret;
+
+	spin_lock_irqsave(&mem->spinlock, flags);
+
+	if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
+		goto err;
+
+	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
+	if (unlikely(pageno < 0))
+		goto err;
+
+	/*
+	 * Memory was found in the coherent area.
+	 */
+	*dma_handle = dma_get_device_base(dev, mem) +
+			((dma_addr_t)pageno << PAGE_SHIFT);
+	ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
+	spin_unlock_irqrestore(&mem->spinlock, flags);
+	memset(ret, 0, size);
+	return ret;
+err:
+	spin_unlock_irqrestore(&mem->spinlock, flags);
+	return NULL;
+}
+
+/**
+ * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
+ * @dev:	device from which we allocate memory
+ * @size:	size of requested memory area
+ * @dma_handle:	This will be filled with the correct dma handle
+ * @ret:	This pointer will be filled with the virtual address
+ *		to allocated area.
+ *
+ * This function should be only called from per-arch dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ *
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
+ */
+int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
+		dma_addr_t *dma_handle, void **ret)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	if (!mem)
+		return 0;
+
+	*ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
+	return 1;
+}
+
+void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
+				     dma_addr_t *dma_handle)
+{
+	if (!dma_coherent_default_memory)
+		return NULL;
+
+	return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
+					 dma_handle);
+}
+
+static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
+				       int order, void *vaddr)
+{
+	if (mem && vaddr >= mem->virt_base && vaddr <
+		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
+		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+		unsigned long flags;
+
+		spin_lock_irqsave(&mem->spinlock, flags);
+		bitmap_release_region(mem->bitmap, page, order);
+		spin_unlock_irqrestore(&mem->spinlock, flags);
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * dma_release_from_dev_coherent() - free memory to device coherent memory pool
+ * @dev:	device from which the memory was allocated
+ * @order:	the order of pages allocated
+ * @vaddr:	virtual address of allocated pages
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ *
+ * Returns 1 if we correctly released the memory, or 0 if the caller should
+ * proceed with releasing memory from generic pools.
+ */
+int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	return __dma_release_from_coherent(mem, order, vaddr);
+}
+
+int dma_release_from_global_coherent(int order, void *vaddr)
+{
+	if (!dma_coherent_default_memory)
+		return 0;
+
+	return __dma_release_from_coherent(dma_coherent_default_memory, order,
+			vaddr);
+}
+
+static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
+		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
+{
+	if (mem && vaddr >= mem->virt_base && vaddr + size <=
+		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
+		unsigned long off = vma->vm_pgoff;
+		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+		unsigned long user_count = vma_pages(vma);
+		int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+		*ret = -ENXIO;
+		if (off < count && user_count <= count - off) {
+			unsigned long pfn = mem->pfn_base + start + off;
+			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
+					       user_count << PAGE_SHIFT,
+					       vma->vm_page_prot);
+		}
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
+ * @dev:	device from which the memory was allocated
+ * @vma:	vm_area for the userspace memory
+ * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
+ * @size:	size of the memory buffer allocated
+ * @ret:	result from remap_pfn_range()
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, maps that memory to the provided vma.
+ *
+ * Returns 1 if @vaddr belongs to the device coherent pool and the caller
+ * should return @ret, or 0 if they should proceed with mapping memory from
+ * generic areas.
+ */
+int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
+			   void *vaddr, size_t size, int *ret)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
+}
+
+int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
+				   size_t size, int *ret)
+{
+	if (!dma_coherent_default_memory)
+		return 0;
+
+	return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
+					vaddr, size, ret);
+}
+
+/*
+ * Support for reserved memory regions defined in device tree
+ */
+#ifdef CONFIG_OF_RESERVED_MEM
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+
+static struct reserved_mem *dma_reserved_default_memory __initdata;
+
+static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
+{
+	struct dma_coherent_mem *mem = rmem->priv;
+	int ret;
+
+	if (!mem) {
+		ret = dma_init_coherent_memory(rmem->base, rmem->base,
+					       rmem->size, &mem);
+		if (ret) {
+			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
+				&rmem->base, (unsigned long)rmem->size / SZ_1M);
+			return ret;
+		}
+	}
+	mem->use_dev_dma_pfn_offset = true;
+	rmem->priv = mem;
+	dma_assign_coherent_memory(dev, mem);
+	return 0;
+}
+
+static void rmem_dma_device_release(struct reserved_mem *rmem,
+				    struct device *dev)
+{
+	if (dev)
+		dev->dma_mem = NULL;
+}
+
+static const struct reserved_mem_ops rmem_dma_ops = {
+	.device_init	= rmem_dma_device_init,
+	.device_release	= rmem_dma_device_release,
+};
+
+static int __init rmem_dma_setup(struct reserved_mem *rmem)
+{
+	unsigned long node = rmem->fdt_node;
+
+	if (of_get_flat_dt_prop(node, "reusable", NULL))
+		return -EINVAL;
+
+#ifdef CONFIG_ARM
+	if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
+		pr_err("Reserved memory: regions without no-map are not yet supported\n");
+		return -EINVAL;
+	}
+
+	if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
+		WARN(dma_reserved_default_memory,
+		     "Reserved memory: region for default DMA coherent area is redefined\n");
+		dma_reserved_default_memory = rmem;
+	}
+#endif
+
+	rmem->ops = &rmem_dma_ops;
+	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
+		&rmem->base, (unsigned long)rmem->size / SZ_1M);
+	return 0;
+}
+
+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;
+}
+
+core_initcall(dma_init_reserved_memory);
+
+RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
+#endif