nds32: DMA mapping API

// 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

// 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);