From: Greentime Hu <greent...@andestech.com>

This patch adds support for the DMA mapping API. It uses dma_map_ops for
flexibility.

Signed-off-by: Vincent Chen <vince...@andestech.com>
Signed-off-by: Greentime Hu <greent...@andestech.com>
---
 arch/nds32/include/asm/dma-mapping.h |   27 ++
 arch/nds32/kernel/dma.c              |  472 ++++++++++++++++++++++++++++++++++
 2 files changed, 499 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 0000000..63dbeb7
--- /dev/null
+++ b/arch/nds32/include/asm/dma-mapping.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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 0000000..9554aee
--- /dev/null
+++ b/arch/nds32/kernel/dma.c
@@ -0,0 +1,472 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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);
+
+/*
+ * 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);
+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)
+{
+       consistent_sync((void *)(page_address(page) + offset), size, dir);
+       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)
+{
+       consistent_sync(phys_to_virt(handle), size, dir);
+}
+
+/*
+ * Make an area consistent for devices.
+ */
+static void consistent_sync(void *vaddr, size_t size, int direction)
+{
+       unsigned long start = (unsigned long)vaddr;
+       unsigned long end = start + size;
+
+       switch (direction) {
+       case DMA_FROM_DEVICE:   /* invalidate only */
+               cpu_dma_inval_range(start, end);
+               break;
+       case DMA_TO_DEVICE:     /* writeback only */
+               cpu_dma_wb_range(start, end);
+               break;
+       case DMA_BIDIRECTIONAL: /* writeback and invalidate */
+               cpu_dma_wbinval_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);
+                       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);
+               }
+       }
+       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);
+}
+
+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);
+}
+
+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);
+       }
+}
+
+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);
+       }
+}
+
+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);
-- 
1.7.9.5

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