metag: DMA

Add DMA mapping code.

Signed-off-by: James Hogan <[e-mail]>

arch/metag/include/asm/dma-mapping.h

···
+#ifndef _ASM_METAG_DMA_MAPPING_H
+#define _ASM_METAG_DMA_MAPPING_H
+
+#include <linux/mm.h>
+
+#include <asm/cache.h>
+#include <asm/io.h>
+#include <linux/scatterlist.h>
+#include <asm/bug.h>
+
+#define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
+#define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)
+
+void *dma_alloc_coherent(struct device *dev, size_t size,
+			 dma_addr_t *dma_handle, gfp_t flag);
+
+void dma_free_coherent(struct device *dev, size_t size,
+		       void *vaddr, dma_addr_t dma_handle);
+
+void dma_sync_for_device(void *vaddr, size_t size, int dma_direction);
+void dma_sync_for_cpu(void *vaddr, size_t size, int dma_direction);
+
+int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
+		      void *cpu_addr, dma_addr_t dma_addr, size_t size);
+
+int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
+			  void *cpu_addr, dma_addr_t dma_addr, size_t size);
+
+static inline dma_addr_t
+dma_map_single(struct device *dev, void *ptr, size_t size,
+	       enum dma_data_direction direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	WARN_ON(size == 0);
+	dma_sync_for_device(ptr, size, direction);
+	return virt_to_phys(ptr);
+}
+
+static inline void
+dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
+		 enum dma_data_direction direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	dma_sync_for_cpu(phys_to_virt(dma_addr), size, direction);
+}
+
+static inline int
+dma_map_sg(struct device *dev, struct scatterlist *sglist, int nents,
+	   enum dma_data_direction direction)
+{
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(!valid_dma_direction(direction));
+	WARN_ON(nents == 0 || sglist[0].length == 0);
+
+	for_each_sg(sglist, sg, nents, i) {
+		BUG_ON(!sg_page(sg));
+
+		sg->dma_address = sg_phys(sg);
+		dma_sync_for_device(sg_virt(sg), sg->length, direction);
+	}
+
+	return nents;
+}
+
+static inline dma_addr_t
+dma_map_page(struct device *dev, struct page *page, unsigned long offset,
+	     size_t size, enum dma_data_direction direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	dma_sync_for_device((void *)(page_to_phys(page) + offset), size,
+			    direction);
+	return page_to_phys(page) + offset;
+}
+
+static inline void
+dma_unmap_page(struct device *dev, dma_addr_t dma_address, size_t size,
+	       enum dma_data_direction direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
+}
+
+
+static inline void
+dma_unmap_sg(struct device *dev, struct scatterlist *sglist, int nhwentries,
+	     enum dma_data_direction direction)
+{
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(!valid_dma_direction(direction));
+	WARN_ON(nhwentries == 0 || sglist[0].length == 0);
+
+	for_each_sg(sglist, sg, nhwentries, i) {
+		BUG_ON(!sg_page(sg));
+
+		sg->dma_address = sg_phys(sg);
+		dma_sync_for_cpu(sg_virt(sg), sg->length, direction);
+	}
+}
+
+static inline void
+dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
+			enum dma_data_direction direction)
+{
+	dma_sync_for_cpu(phys_to_virt(dma_handle), size, direction);
+}
+
+static inline void
+dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
+			   size_t size, enum dma_data_direction direction)
+{
+	dma_sync_for_device(phys_to_virt(dma_handle), size, direction);
+}
+
+static inline void
+dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t dma_handle,
+			      unsigned long offset, size_t size,
+			      enum dma_data_direction direction)
+{
+	dma_sync_for_cpu(phys_to_virt(dma_handle)+offset, size,
+			 direction);
+}
+
+static inline void
+dma_sync_single_range_for_device(struct device *dev, dma_addr_t dma_handle,
+				 unsigned long offset, size_t size,
+				 enum dma_data_direction direction)
+{
+	dma_sync_for_device(phys_to_virt(dma_handle)+offset, size,
+			    direction);
+}
+
+static inline void
+dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nelems,
+		    enum dma_data_direction direction)
+{
+	int i;
+	for (i = 0; i < nelems; i++, sg++)
+		dma_sync_for_cpu(sg_virt(sg), sg->length, direction);
+}
+
+static inline void
+dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
+		       enum dma_data_direction direction)
+{
+	int i;
+	for (i = 0; i < nelems; i++, sg++)
+		dma_sync_for_device(sg_virt(sg), sg->length, direction);
+}
+
+static inline int
+dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	return 0;
+}
+
+#define dma_supported(dev, mask)        (1)
+
+static inline int
+dma_set_mask(struct device *dev, u64 mask)
+{
+	if (!dev->dma_mask || !dma_supported(dev, mask))
+		return -EIO;
+
+	*dev->dma_mask = mask;
+
+	return 0;
+}
+
+/*
+ * dma_alloc_noncoherent() returns non-cacheable memory, so there's no need to
+ * do any flushing here.
+ */
+static inline void
+dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+	       enum dma_data_direction direction)
+{
+}
+
+#endif

arch/metag/kernel/dma.c

···
+/*
+ *  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 ([e-mail])
+ *
+ *  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 <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/highmem.h>
+#include <linux/dma-mapping.h>
+#include <linux/slab.h>
+
+#include <asm/tlbflush.h>
+#include <asm/mmu.h>
+
+#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);
+				ClearPageReserved(page);
+
+				__free_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);
+		if (!pmd) {
+			pr_err("%s: no pmd tables\n", __func__);
+			ret = -ENOMEM;
+			break;
+		}
+		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);