/*
* SWIOTLB-based DMA API implementation
*
* Copyright (C) 2012 ARM Ltd.
* Author: Catalin Marinas <catalin.marinas@arm.com>
*
* 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/gfp.h>
#include <linux/acpi.h>
#include <linux/bootmem.h>
#include <linux/cache.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/genalloc.h>
#include <linux/dma-direct.h>
#include <linux/dma-contiguous.h>
#include <linux/vmalloc.h>
#include <linux/swiotlb.h>
#include <linux/pci.h>
#include <asm/cacheflush.h>
static int swiotlb __ro_after_init;
static pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot,
bool coherent)
{
if (!coherent || (attrs & DMA_ATTR_WRITE_COMBINE))
return pgprot_writecombine(prot);
return prot;
}
static struct gen_pool *atomic_pool __ro_after_init;
#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K
static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
static int __init early_coherent_pool(char *p)
{
atomic_pool_size = memparse(p, &p);
return 0;
}
early_param("coherent_pool", early_coherent_pool);
static void *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
{
unsigned long val;
void *ptr = NULL;
if (!atomic_pool) {
WARN(1, "coherent pool not initialised!\n");
return NULL;
}
val = gen_pool_alloc(atomic_pool, size);
if (val) {
phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
*ret_page = phys_to_page(phys);
ptr = (void *)val;
memset(ptr, 0, size);
}
return ptr;
}
static bool __in_atomic_pool(void *start, size_t size)
{
return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
}
static int __free_from_pool(void *start, size_t size)
{
if (!__in_atomic_pool(start, size))
return 0;
gen_pool_free(atomic_pool, (unsigned long)start, size);
return 1;
}
static void *__dma_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
unsigned long attrs)
{
struct page *page;
void *ptr, *coherent_ptr;
bool coherent = is_device_dma_coherent(dev);
pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
size = PAGE_ALIGN(size);
if (!coherent && !gfpflags_allow_blocking(flags)) {
struct page *page = NULL;
void *addr = __alloc_from_pool(size, &page, flags);
if (addr)
*dma_handle = phys_to_dma(dev, page_to_phys(page));
return addr;
}
ptr = swiotlb_alloc(dev, size, dma_handle, flags, attrs);
if (!ptr)
goto no_mem;
/* no need for non-cacheable mapping if coherent */
if (coherent)
return ptr;
/* remove any dirty cache lines on the kernel alias */
__dma_flush_area(ptr, size);
/* create a coherent mapping */
page = virt_to_page(ptr);
coherent_ptr = dma_common_contiguous_remap(page, size, VM_USERMAP,
prot, __builtin_return_address(0));
if (!coherent_ptr)
goto no_map;
return coherent_ptr;
no_map:
swiotlb_free(dev, size, ptr, *dma_handle, attrs);
no_mem:
return NULL;
}
static void __dma_free(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
unsigned long attrs)
{
void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
size = PAGE_ALIGN(size);
if (!is_device_dma_coherent(dev)) {
if (__free_from_pool(vaddr, size))
return;
vunmap(vaddr);
}
swiotlb_free(dev, size, swiotlb_addr, dma_handle, attrs);
}
static dma_addr_t __swiotlb_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
unsigned long attrs)
{
dma_addr_t dev_addr;
dev_addr = swiotlb_map_page(dev, page, offset, size, dir, attrs);
if (!is_device_dma_coherent(dev) &&
(attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
__dma_map_area(phys_to_virt(dma_to_phys(dev, dev_addr)), size, dir);
return dev_addr;
}