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Subject[PATCH v7 17/37] nds32: DMA mapping API
Date
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 | 14 +
arch/nds32/kernel/dma.c | 477 +++++++++++++++++++++++++++++++++++
2 files changed, 491 insertions(+)
create mode 100644 arch/nds32/include/asm/dma-mapping.h
create mode 100644 arch/nds32/kernel/dma.c

diff --git a/arch/nds32/include/asm/dma-mapping.h b/arch/nds32/include/asm/dma-mapping.h
new file mode 100644
index 000000000000..2dd47d245c25
--- /dev/null
+++ b/arch/nds32/include/asm/dma-mapping.h
@@ -0,0 +1,14 @@
+// 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
diff --git a/arch/nds32/kernel/dma.c b/arch/nds32/kernel/dma.c
new file mode 100644
index 000000000000..d291800fc621
--- /dev/null
+++ b/arch/nds32/kernel/dma.c
@@ -0,0 +1,477 @@
+// 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);
--
2.16.1
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