nds32: DMA mapping API

This patch adds support for the DMA mapping API. It uses dma_map_ops for
flexibility.
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/nds32/include/asm/dma-mapping.h

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef ASMNDS32_DMA_MAPPING_H
+#define ASMNDS32_DMA_MAPPING_H
+
+extern struct dma_map_ops nds32_dma_ops;
+
+static inline struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
+{
+	return &nds32_dma_ops;
+}
+
+#endif

arch/nds32/kernel/dma.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/string.h>
+#include <linux/scatterlist.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/cache.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/dma-mapping.h>
+#include <asm/proc-fns.h>
+
+/*
+ * This is the page table (2MB) covering uncached, DMA consistent allocations
+ */
+static pte_t *consistent_pte;
+static DEFINE_RAW_SPINLOCK(consistent_lock);
+
+enum master_type {
+	FOR_CPU = 0,
+	FOR_DEVICE = 1,
+};
+
+/*
+ * 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 vm_region	region;
+ *    unsigned long	flags;
+ *    struct page	**pages;
+ *    unsigned int	nr_pages;
+ *    unsigned long	phys_addr;
+ *  };
+ *
+ * get_vm_area() would then call vm_region_alloc with an appropriate
+ * struct vm_region head (eg):
+ *
+ *  struct 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 vm_region_alloc().
+ */
+struct arch_vm_region {
+	struct list_head vm_list;
+	unsigned long vm_start;
+	unsigned long vm_end;
+	struct page *vm_pages;
+};
+
+static struct arch_vm_region consistent_head = {
+	.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
+	.vm_start = CONSISTENT_BASE,
+	.vm_end = CONSISTENT_END,
+};
+
+static struct arch_vm_region *vm_region_alloc(struct arch_vm_region *head,
+					      size_t size, int gfp)
+{
+	unsigned long addr = head->vm_start, end = head->vm_end - size;
+	unsigned long flags;
+	struct arch_vm_region *c, *new;
+
+	new = kmalloc(sizeof(struct arch_vm_region), gfp);
+	if (!new)
+		goto out;
+
+	raw_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;
+
+	raw_spin_unlock_irqrestore(&consistent_lock, flags);
+	return new;
+
+nospc:
+	raw_spin_unlock_irqrestore(&consistent_lock, flags);
+	kfree(new);
+out:
+	return NULL;
+}
+
+static struct arch_vm_region *vm_region_find(struct arch_vm_region *head,
+					     unsigned long addr)
+{
+	struct arch_vm_region *c;
+
+	list_for_each_entry(c, &head->vm_list, vm_list) {
+		if (c->vm_start == addr)
+			goto out;
+	}
+	c = NULL;
+out:
+	return c;
+}
+
+/* FIXME: attrs is not used. */
+static void *nds32_dma_alloc_coherent(struct device *dev, size_t size,
+				      dma_addr_t * handle, gfp_t gfp,
+				      unsigned long attrs)
+{
+	struct page *page;
+	struct arch_vm_region *c;
+	unsigned long order;
+	u64 mask = ~0ULL, limit;
+	pgprot_t prot = pgprot_noncached(PAGE_KERNEL);
+
+	if (!consistent_pte) {
+		pr_err("%s: not initialized\n", __func__);
+		dump_stack();
+		return NULL;
+	}
+
+	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");
+			goto no_page;
+		}
+
+	}
+
+	/*
+	 * Sanity check the allocation size.
+	 */
+	size = PAGE_ALIGN(size);
+	limit = (mask + 1) & ~mask;
+	if ((limit && size >= limit) ||
+	    size >= (CONSISTENT_END - CONSISTENT_BASE)) {
+		pr_warn("coherent allocation too big "
+			"(requested %#x mask %#llx)\n", size, mask);
+		goto no_page;
+	}
+
+	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.
+	 */
+	{
+		unsigned long kaddr = (unsigned long)page_address(page);
+		memset(page_address(page), 0, size);
+		cpu_dma_wbinval_range(kaddr, kaddr + size);
+	}
+
+	/*
+	 * Allocate a virtual address in the consistent mapping region.
+	 */
+	c = vm_region_alloc(&consistent_head, size,
+			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
+	if (c) {
+		pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
+		struct page *end = page + (1 << order);
+
+		c->vm_pages = page;
+
+		/*
+		 * Set the "dma handle"
+		 */
+		*handle = page_to_phys(page);
+
+		do {
+			BUG_ON(!pte_none(*pte));
+
+			/*
+			 * x86 does not mark the pages reserved...
+			 */
+			SetPageReserved(page);
+			set_pte(pte, mk_pte(page, prot));
+			page++;
+			pte++;
+		} 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:
+	*handle = ~0;
+	return NULL;
+}
+
+static void nds32_dma_free(struct device *dev, size_t size, void *cpu_addr,
+			   dma_addr_t handle, unsigned long attrs)
+{
+	struct arch_vm_region *c;
+	unsigned long flags, addr;
+	pte_t *ptep;
+
+	size = PAGE_ALIGN(size);
+
+	raw_spin_lock_irqsave(&consistent_lock, flags);
+
+	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
+	if (!c)
+		goto no_area;
+
+	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);
+
+				/*
+				 * x86 does not mark the pages reserved...
+				 */
+				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);
+
+	raw_spin_unlock_irqrestore(&consistent_lock, flags);
+
+	kfree(c);
+	return;
+
+no_area:
+	raw_spin_unlock_irqrestore(&consistent_lock, flags);
+	pr_err("%s: trying to free invalid coherent area: %p\n",
+	       __func__, cpu_addr);
+	dump_stack();
+}
+
+/*
+ * Initialise the consistent memory allocation.
+ */
+static int __init consistent_init(void)
+{
+	pgd_t *pgd;
+	pmd_t *pmd;
+	pte_t *pte;
+	int ret = 0;
+
+	do {
+		pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
+		pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
+		if (!pmd) {
+			pr_err("%s: no pmd tables\n", __func__);
+			ret = -ENOMEM;
+			break;
+		}
+		/* The first level mapping may be created in somewhere.
+		 * It's not necessary to warn here. */
+		/* WARN_ON(!pmd_none(*pmd)); */
+
+		pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
+		if (!pte) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		consistent_pte = pte;
+	} while (0);
+
+	return ret;
+}
+
+core_initcall(consistent_init);
+static void consistent_sync(void *vaddr, size_t size, int direction, int master_type);
+static dma_addr_t nds32_dma_map_page(struct device *dev, struct page *page,
+				     unsigned long offset, size_t size,
+				     enum dma_data_direction dir,
+				     unsigned long attrs)
+{
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		consistent_sync((void *)(page_address(page) + offset), size, dir, FOR_DEVICE);
+	return page_to_phys(page) + offset;
+}
+
+static void nds32_dma_unmap_page(struct device *dev, dma_addr_t handle,
+				 size_t size, enum dma_data_direction dir,
+				 unsigned long attrs)
+{
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		consistent_sync(phys_to_virt(handle), size, dir, FOR_CPU);
+}
+
+/*
+ * Make an area consistent for devices.
+ */
+static void consistent_sync(void *vaddr, size_t size, int direction, int master_type)
+{
+	unsigned long start = (unsigned long)vaddr;
+	unsigned long end = start + size;
+
+	if (master_type == FOR_CPU) {
+		switch (direction) {
+		case DMA_TO_DEVICE:
+			break;
+		case DMA_FROM_DEVICE:
+		case DMA_BIDIRECTIONAL:
+			cpu_dma_inval_range(start, end);
+			break;
+		default:
+			BUG();
+		}
+	} else {
+		/* FOR_DEVICE */
+		switch (direction) {
+		case DMA_FROM_DEVICE:
+			break;
+		case DMA_TO_DEVICE:
+		case DMA_BIDIRECTIONAL:
+			cpu_dma_wb_range(start, end);
+			break;
+		default:
+			BUG();
+		}
+	}
+}
+
+static int nds32_dma_map_sg(struct device *dev, struct scatterlist *sg,
+			    int nents, enum dma_data_direction dir,
+			    unsigned long attrs)
+{
+	int i;
+
+	for (i = 0; i < nents; i++, sg++) {
+		void *virt;
+		unsigned long pfn;
+		struct page *page = sg_page(sg);
+
+		sg->dma_address = sg_phys(sg);
+		pfn = page_to_pfn(page) + sg->offset / PAGE_SIZE;
+		page = pfn_to_page(pfn);
+		if (PageHighMem(page)) {
+			virt = kmap_atomic(page);
+			consistent_sync(virt, sg->length, dir, FOR_CPU);
+			kunmap_atomic(virt);
+		} else {
+			if (sg->offset > PAGE_SIZE)
+				panic("sg->offset:%08x > PAGE_SIZE\n",
+				      sg->offset);
+			virt = page_address(page) + sg->offset;
+			consistent_sync(virt, sg->length, dir, FOR_CPU);
+		}
+	}
+	return nents;
+}
+
+static void nds32_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
+			       int nhwentries, enum dma_data_direction dir,
+			       unsigned long attrs)
+{
+}
+
+static void
+nds32_dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,
+			      size_t size, enum dma_data_direction dir)
+{
+	consistent_sync((void *)phys_to_virt(handle), size, dir, FOR_CPU);
+}
+
+static void
+nds32_dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
+				 size_t size, enum dma_data_direction dir)
+{
+	consistent_sync((void *)phys_to_virt(handle), size, dir, FOR_DEVICE);
+}
+
+static void
+nds32_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
+			  enum dma_data_direction dir)
+{
+	int i;
+
+	for (i = 0; i < nents; i++, sg++) {
+		char *virt =
+		    page_address((struct page *)sg->page_link) + sg->offset;
+		consistent_sync(virt, sg->length, dir, FOR_CPU);
+	}
+}
+
+static void
+nds32_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
+			     int nents, enum dma_data_direction dir)
+{
+	int i;
+
+	for (i = 0; i < nents; i++, sg++) {
+		char *virt =
+		    page_address((struct page *)sg->page_link) + sg->offset;
+		consistent_sync(virt, sg->length, dir, FOR_DEVICE);
+	}
+}
+
+struct dma_map_ops nds32_dma_ops = {
+	.alloc = nds32_dma_alloc_coherent,
+	.free = nds32_dma_free,
+	.map_page = nds32_dma_map_page,
+	.unmap_page = nds32_dma_unmap_page,
+	.map_sg = nds32_dma_map_sg,
+	.unmap_sg = nds32_dma_unmap_sg,
+	.sync_single_for_device = nds32_dma_sync_single_for_device,
+	.sync_single_for_cpu = nds32_dma_sync_single_for_cpu,
+	.sync_sg_for_cpu = nds32_dma_sync_sg_for_cpu,
+	.sync_sg_for_device = nds32_dma_sync_sg_for_device,
+};
+
+EXPORT_SYMBOL(nds32_dma_ops);