alistair23-linux/arch/xtensa/kernel/pci-dma.c

/*
 * DMA coherent memory allocation.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 *
 * Copyright (C) 2002 - 2005 Tensilica Inc.
 * Copyright (C) 2015 Cadence Design Systems Inc.
 *
 * Based on version for i386.
 *
 * Chris Zankel <chris@zankel.net>
 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
 */

#include <linux/dma-contiguous.h>
#include <linux/dma-noncoherent.h>
#include <linux/dma-direct.h>
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/platform.h>

static void do_cache_op(phys_addr_t paddr, size_t size,
			void (*fn)(unsigned long, unsigned long))
{
	unsigned long off = paddr & (PAGE_SIZE - 1);
	unsigned long pfn = PFN_DOWN(paddr);
	struct page *page = pfn_to_page(pfn);

	if (!PageHighMem(page))
		fn((unsigned long)phys_to_virt(paddr), size);
	else
		while (size > 0) {
			size_t sz = min_t(size_t, size, PAGE_SIZE - off);
			void *vaddr = kmap_atomic(page);

			fn((unsigned long)vaddr + off, sz);
			kunmap_atomic(vaddr);
			off = 0;
			++page;
			size -= sz;
		}
}

void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
		size_t size, enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_BIDIRECTIONAL:
	case DMA_FROM_DEVICE:
		do_cache_op(paddr, size, __invalidate_dcache_range);
		break;

	case DMA_NONE:
		BUG();
		break;

	default:
		break;
	}
}

void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
		size_t size, enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_BIDIRECTIONAL:
	case DMA_TO_DEVICE:
		if (XCHAL_DCACHE_IS_WRITEBACK)
			do_cache_op(paddr, size, __flush_dcache_range);
		break;

	case DMA_NONE:
		BUG();
		break;

	default:
		break;
	}
}

#ifdef CONFIG_MMU
bool platform_vaddr_cached(const void *p)
{
	unsigned long addr = (unsigned long)p;

	return addr >= XCHAL_KSEG_CACHED_VADDR &&
	       addr - XCHAL_KSEG_CACHED_VADDR < XCHAL_KSEG_SIZE;
}

bool platform_vaddr_uncached(const void *p)
{
	unsigned long addr = (unsigned long)p;

	return addr >= XCHAL_KSEG_BYPASS_VADDR &&
	       addr - XCHAL_KSEG_BYPASS_VADDR < XCHAL_KSEG_SIZE;
}

void *platform_vaddr_to_uncached(void *p)
{
	return p + XCHAL_KSEG_BYPASS_VADDR - XCHAL_KSEG_CACHED_VADDR;
}

void *platform_vaddr_to_cached(void *p)
{
	return p + XCHAL_KSEG_CACHED_VADDR - XCHAL_KSEG_BYPASS_VADDR;
}
#else
bool __attribute__((weak)) platform_vaddr_cached(const void *p)
{
	WARN_ONCE(1, "Default %s implementation is used\n", __func__);
	return true;
}

bool __attribute__((weak)) platform_vaddr_uncached(const void *p)
{
	WARN_ONCE(1, "Default %s implementation is used\n", __func__);
	return false;
}

void __attribute__((weak)) *platform_vaddr_to_uncached(void *p)
{
	WARN_ONCE(1, "Default %s implementation is used\n", __func__);
	return p;
}

void __attribute__((weak)) *platform_vaddr_to_cached(void *p)
{
	WARN_ONCE(1, "Default %s implementation is used\n", __func__);
	return p;
}
#endif

/*
 * Note: We assume that the full memory space is always mapped to 'kseg'
 *	 Otherwise we have to use page attributes (not implemented).
 */

void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
		gfp_t flag, unsigned long attrs)
{
	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	struct page *page = NULL;

	/* ignore region speicifiers */

	flag &= ~(__GFP_DMA | __GFP_HIGHMEM);

	if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
		flag |= GFP_DMA;

	if (gfpflags_allow_blocking(flag))
		page = dma_alloc_from_contiguous(dev, count, get_order(size),
						 flag & __GFP_NOWARN);

	if (!page)
		page = alloc_pages(flag | __GFP_ZERO, get_order(size));

	if (!page)
		return NULL;

	*handle = phys_to_dma(dev, page_to_phys(page));

	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
		return page;
	}

#ifdef CONFIG_MMU
	if (PageHighMem(page)) {
		void *p;

		p = dma_common_contiguous_remap(page, size, VM_MAP,
						pgprot_noncached(PAGE_KERNEL),
						__builtin_return_address(0));
		if (!p) {
			if (!dma_release_from_contiguous(dev, page, count))
				__free_pages(page, get_order(size));
		}
		return p;
	}
#endif
	BUG_ON(!platform_vaddr_cached(page_address(page)));
	__invalidate_dcache_range((unsigned long)page_address(page), size);
	return platform_vaddr_to_uncached(page_address(page));
}

void arch_dma_free(struct device *dev, size_t size, void *vaddr,
		dma_addr_t dma_handle, unsigned long attrs)
{
	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	struct page *page;

	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
		page = vaddr;
	} else if (platform_vaddr_uncached(vaddr)) {
		page = virt_to_page(platform_vaddr_to_cached(vaddr));
	} else {
#ifdef CONFIG_MMU
		dma_common_free_remap(vaddr, size, VM_MAP);
#endif
		page = pfn_to_page(PHYS_PFN(dma_to_phys(dev, dma_handle)));
	}

	if (!dma_release_from_contiguous(dev, page, count))
		__free_pages(page, get_order(size));
}