// 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; } 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