/* * Meta version derived from arch/powerpc/lib/dma-noncoherent.c * Copyright (C) 2008 Imagination Technologies Ltd. * * PowerPC version derived from arch/arm/mm/consistent.c * Copyright (C) 2001 Dan Malek (dmalek@jlc.net) * * Copyright (C) 2000 Russell King * * Consistent memory allocators. Used for DMA devices that want to * share uncached memory with the processor core. The function return * is the virtual address and 'dma_handle' is the physical address. * Mostly stolen from the ARM port, with some changes for PowerPC. * -- Dan * * Reorganized to get rid of the arch-specific consistent_* functions * and provide non-coherent implementations for the DMA API. -Matt * * Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent() * implementation. This is pulled straight from ARM and barely * modified. -Matt * * 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. */ #include #include #include #include #include #include #include #include #include #include #include #define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_START) \ >> PAGE_SHIFT) static u64 get_coherent_dma_mask(struct device *dev) { u64 mask = ~0ULL; if (dev) { mask = dev->coherent_dma_mask; /* * Sanity check the DMA mask - it must be non-zero, and * must be able to be satisfied by a DMA allocation. */ if (mask == 0) { dev_warn(dev, "coherent DMA mask is unset\n"); return 0; } } return mask; } /* * This is the page table (2MB) covering uncached, DMA consistent allocations */ static pte_t *consistent_pte; static DEFINE_SPINLOCK(consistent_lock); /* * VM region handling support. * * This should become something generic, handling VM region allocations for * vmalloc and similar (ioremap, module space, etc). * * I envisage vmalloc()'s supporting vm_struct becoming: * * struct vm_struct { * struct metag_vm_region region; * unsigned long flags; * struct page **pages; * unsigned int nr_pages; * unsigned long phys_addr; * }; * * get_vm_area() would then call metag_vm_region_alloc with an appropriate * struct metag_vm_region head (eg): * * struct metag_vm_region vmalloc_head = { * .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list), * .vm_start = VMALLOC_START, * .vm_end = VMALLOC_END, * }; * * However, vmalloc_head.vm_start is variable (typically, it is dependent on * the amount of RAM found at boot time.) I would imagine that get_vm_area() * would have to initialise this each time prior to calling * metag_vm_region_alloc(). */ struct metag_vm_region { struct list_head vm_list; unsigned long vm_start; unsigned long vm_end; struct page *vm_pages; int vm_active; }; static struct metag_vm_region consistent_head = { .vm_list = LIST_HEAD_INIT(consistent_head.vm_list), .vm_start = CONSISTENT_START, .vm_end = CONSISTENT_END, }; static struct metag_vm_region *metag_vm_region_alloc(struct metag_vm_region *head, size_t size, gfp_t gfp) { unsigned long addr = head->vm_start, end = head->vm_end - size; unsigned long flags; struct metag_vm_region *c, *new; new = kmalloc(sizeof(struct metag_vm_region), gfp); if (!new) goto out; spin_lock_irqsave(&consistent_lock, flags); list_for_each_entry(c, &head->vm_list, vm_list) { if ((addr + size) < addr) goto nospc; if ((addr + size) <= c->vm_start) goto found; addr = c->vm_end; if (addr > end) goto nospc; } found: /* * Insert this entry _before_ the one we found. */ list_add_tail(&new->vm_list, &c->vm_list); new->vm_start = addr; new->vm_end = addr + size; new->vm_active = 1; spin_unlock_irqrestore(&consistent_lock, flags); return new; nospc: spin_unlock_irqrestore(&consistent_lock, flags); kfree(new); out: return NULL; } static struct metag_vm_region *metag_vm_region_find(struct metag_vm_region *head, unsigned long addr) { struct metag_vm_region *c; list_for_each_entry(c, &head->vm_list, vm_list) { if (c->vm_active && c->vm_start == addr) goto out; } c = NULL; out: return c; } /* * Allocate DMA-coherent memory space and return both the kernel remapped * virtual and bus address for that space. */ void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) { struct page *page; struct metag_vm_region *c; unsigned long order; u64 mask = get_coherent_dma_mask(dev); u64 limit; if (!consistent_pte) { pr_err("%s: not initialised\n", __func__); dump_stack(); return NULL; } if (!mask) goto no_page; size = PAGE_ALIGN(size); limit = (mask + 1) & ~mask; if ((limit && size >= limit) || size >= (CONSISTENT_END - CONSISTENT_START)) { pr_warn("coherent allocation too big (requested %#x mask %#Lx)\n", size, mask); return NULL; } order = get_order(size); if (mask != 0xffffffff) gfp |= GFP_DMA; page = alloc_pages(gfp, order); if (!page) goto no_page; /* * Invalidate any data that might be lurking in the * kernel direct-mapped region for device DMA. */ { void *kaddr = page_address(page); memset(kaddr, 0, size); flush_dcache_region(kaddr, size); } /* * Allocate a virtual address in the consistent mapping region. */ c = metag_vm_region_alloc(&consistent_head, size, gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); if (c) { unsigned long vaddr = c->vm_start; pte_t *pte = consistent_pte + CONSISTENT_OFFSET(vaddr); struct page *end = page + (1 << order); c->vm_pages = page; split_page(page, order); /* * Set the "dma handle" */ *handle = page_to_bus(page); do { BUG_ON(!pte_none(*pte)); SetPageReserved(page); set_pte_at(&init_mm, vaddr, pte, mk_pte(page, pgprot_writecombine (PAGE_KERNEL))); page++; pte++; vaddr += PAGE_SIZE; } while (size -= PAGE_SIZE); /* * Free the otherwise unused pages. */ while (page < end) { __free_page(page); page++; } return (void *)c->vm_start; } if (page) __free_pages(page, order); no_page: return NULL; } EXPORT_SYMBOL(dma_alloc_coherent); /* * free a page as defined by the above mapping. */ void dma_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle) { struct metag_vm_region *c; unsigned long flags, addr; pte_t *ptep; size = PAGE_ALIGN(size); spin_lock_irqsave(&consistent_lock, flags); c = metag_vm_region_find(&consistent_head, (unsigned long)vaddr); if (!c) goto no_area; c->vm_active = 0; if ((c->vm_end - c->vm_start) != size) { pr_err("%s: freeing wrong coherent size (%ld != %d)\n", __func__, c->vm_end - c->vm_start, size); dump_stack(); size = c->vm_end - c->vm_start; } ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start); addr = c->vm_start; do { pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep); unsigned long pfn; ptep++; addr += PAGE_SIZE; if (!pte_none(pte) && pte_present(pte)) { pfn = pte_pfn(pte); if (pfn_valid(pfn)) { struct page *page = pfn_to_page(pfn); __free_reserved_page(page); continue; } } pr_crit("%s: bad page in kernel page table\n", __func__); } while (size -= PAGE_SIZE); flush_tlb_kernel_range(c->vm_start, c->vm_end); list_del(&c->vm_list); spin_unlock_irqrestore(&consistent_lock, flags); kfree(c); return; no_area: spin_unlock_irqrestore(&consistent_lock, flags); pr_err("%s: trying to free invalid coherent area: %p\n", __func__, vaddr); dump_stack(); } EXPORT_SYMBOL(dma_free_coherent); static int dma_mmap(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { int ret = -ENXIO; unsigned long flags, user_size, kern_size; struct metag_vm_region *c; user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; spin_lock_irqsave(&consistent_lock, flags); c = metag_vm_region_find(&consistent_head, (unsigned long)cpu_addr); spin_unlock_irqrestore(&consistent_lock, flags); if (c) { unsigned long off = vma->vm_pgoff; kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT; if (off < kern_size && user_size <= (kern_size - off)) { ret = remap_pfn_range(vma, vma->vm_start, page_to_pfn(c->vm_pages) + off, user_size << PAGE_SHIFT, vma->vm_page_prot); } } return ret; } int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); return dma_mmap(dev, vma, cpu_addr, dma_addr, size); } EXPORT_SYMBOL(dma_mmap_coherent); int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); return dma_mmap(dev, vma, cpu_addr, dma_addr, size); } EXPORT_SYMBOL(dma_mmap_writecombine); /* * Initialise the consistent memory allocation. */ static int __init dma_alloc_init(void) { pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pte_t *pte; int ret = 0; do { int offset = pgd_index(CONSISTENT_START); pgd = pgd_offset(&init_mm, CONSISTENT_START); pud = pud_alloc(&init_mm, pgd, CONSISTENT_START); pmd = pmd_alloc(&init_mm, pud, CONSISTENT_START); WARN_ON(!pmd_none(*pmd)); pte = pte_alloc_kernel(pmd, CONSISTENT_START); if (!pte) { pr_err("%s: no pte tables\n", __func__); ret = -ENOMEM; break; } pgd_k = ((pgd_t *) mmu_get_base()) + offset; pud_k = pud_offset(pgd_k, CONSISTENT_START); pmd_k = pmd_offset(pud_k, CONSISTENT_START); set_pmd(pmd_k, *pmd); consistent_pte = pte; } while (0); return ret; } early_initcall(dma_alloc_init); /* * make an area consistent to devices. */ void dma_sync_for_device(void *vaddr, size_t size, int dma_direction) { /* * Ensure any writes get through the write combiner. This is necessary * even with DMA_FROM_DEVICE, or the write may dirty the cache after * we've invalidated it and get written back during the DMA. */ barrier(); switch (dma_direction) { case DMA_BIDIRECTIONAL: /* * Writeback to ensure the device can see our latest changes and * so that we have no dirty lines, and invalidate the cache * lines too in preparation for receiving the buffer back * (dma_sync_for_cpu) later. */ flush_dcache_region(vaddr, size); break; case DMA_TO_DEVICE: /* * Writeback to ensure the device can see our latest changes. * There's no need to invalidate as the device shouldn't write * to the buffer. */ writeback_dcache_region(vaddr, size); break; case DMA_FROM_DEVICE: /* * Invalidate to ensure we have no dirty lines that could get * written back during the DMA. It's also safe to flush * (writeback) here if necessary. */ invalidate_dcache_region(vaddr, size); break; case DMA_NONE: BUG(); } wmb(); } EXPORT_SYMBOL(dma_sync_for_device); /* * make an area consistent to the core. */ void dma_sync_for_cpu(void *vaddr, size_t size, int dma_direction) { /* * Hardware L2 cache prefetch doesn't occur across 4K physical * boundaries, however according to Documentation/DMA-API-HOWTO.txt * kmalloc'd memory is DMA'able, so accesses in nearby memory could * trigger a cache fill in the DMA buffer. * * This should never cause dirty lines, so a flush or invalidate should * be safe to allow us to see data from the device. */ if (_meta_l2c_pf_is_enabled()) { switch (dma_direction) { case DMA_BIDIRECTIONAL: case DMA_FROM_DEVICE: invalidate_dcache_region(vaddr, size); break; case DMA_TO_DEVICE: /* The device shouldn't have written to the buffer */ break; case DMA_NONE: BUG(); } } rmb(); } EXPORT_SYMBOL(dma_sync_for_cpu);