- 根目录:
- arch
- arm
- common
- dmabounce.c
/*
* arch/arm/common/dmabounce.c
*
* Special dma_{map/unmap/dma_sync}_* routines for systems that have
* limited DMA windows. These functions utilize bounce buffers to
* copy data to/from buffers located outside the DMA region. This
* only works for systems in which DMA memory is at the bottom of
* RAM, the remainder of memory is at the top and the DMA memory
* can be marked as ZONE_DMA. Anything beyond that such as discontiguous
* DMA windows will require custom implementations that reserve memory
* areas at early bootup.
*
* Original version by Brad Parker (brad@heeltoe.com)
* Re-written by Christopher Hoover <ch@murgatroid.com>
* Made generic by Deepak Saxena <dsaxena@plexity.net>
*
* Copyright (C) 2002 Hewlett Packard Company.
* Copyright (C) 2004 MontaVista Software, Inc.
*
* 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.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/page-flags.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/list.h>
#include <linux/scatterlist.h>
#include <asm/cacheflush.h>
#undef STATS
#ifdef STATS
#define DO_STATS(X) do { X ; } while (0)
#else
#define DO_STATS(X) do { } while (0)
#endif
/* ************************************************** */
struct safe_buffer {
struct list_head node;
/* original request */
void *ptr;
size_t size;
int direction;
/* safe buffer info */
struct dmabounce_pool *pool;
void *safe;
dma_addr_t safe_dma_addr;
};
struct dmabounce_pool {
unsigned long size;
struct dma_pool *pool;
#ifdef STATS
unsigned long allocs;
#endif
};
struct dmabounce_device_info {
struct device *dev;
struct list_head safe_buffers;
#ifdef STATS
unsigned long total_allocs;
unsigned long map_op_count;
unsigned long bounce_count;
int attr_res;
#endif
struct dmabounce_pool small;
struct dmabounce_pool large;
rwlock_t lock;
int (*needs_bounce)(struct device *, dma_addr_t, size_t);
};
#ifdef STATS
static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
device_info->small.allocs,
device_info->large.allocs,
device_info->total_allocs - device_info->small.allocs -
device_info->large.allocs,
device_info->total_allocs,
device_info->map_op_count,
device_info->bounce_count);
}
static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
#endif
/* allocate a 'safe' buffer and keep track of it */
static inline struct safe_buffer *
alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
size_t size, enum dma_data_direction dir)
{
struct safe_buffer *buf;
struct dmabounce_pool *pool;
struct device *dev = device_info->dev;
unsigned long flags;
dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
__func__, ptr, size, dir);
if (size <= device_info->small.size) {
pool = &device_info->small;
} else if (size <= device_info->large.size) {
pool = &device_info->large;
} else {
pool = NULL;
}
buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
if (buf == NULL) {
dev_warn(dev, "%s: kmalloc failed\n", __func__);
return NULL;
}
buf->ptr = ptr;
buf->size = size;
buf->direction = dir;
buf->pool = pool;
if (pool) {
buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
&buf->safe_dma_addr);
} else {
buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
GFP_ATOMIC);
}
if (buf->safe == NULL) {
dev_warn(dev,
"%s: could not alloc dma memory (size=%d)\n",
__func__, size);
kfree(buf);
return NULL;
}
#ifdef STATS
if (pool)
pool->allocs++;
device_info->total_allocs++;
#endif
write_lock_irqsave(&device_info->lock, flags);
list_add(&buf->node, &device_info->safe_buffers);
write_unlock_irqrestore(&device_info->lock, flags);
return buf;
}
/* determine if a buffer is from our "safe" pool */
static inline struct safe_buffer *
find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
{
struct safe_buffer *b, *rb = NULL;
unsigned long flags;
read_lock_irqsave(&device_info->lock, flags);
list_for_each_entry(b, &device_info->safe_buffers, node)
if (b->safe_dma_addr <= safe_dma_addr &&
b->safe_dma_addr + b->size > safe_dma_addr) {
rb = b;
break;
}
read_unlock_irqrestore(&device_info->lock, flags);
return rb;
}
static inline void
free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
{
unsigned long flags;
dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
write_lock_irqsave(&device_info->lock, flags);
list_del(&buf->node);
write_unlock_irqrestore(&device_info->lock, flags);
if (buf->pool)
dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
else
dma_free_coherent(device_info->dev, buf->size, buf->safe,
buf->safe_dma_addr);
kfree(buf);
}
/* ************************************************** */
static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
dma_addr_t dma_addr, const char *where)
{
if (!dev || !dev->archdata.dmabounce)
return NULL;
if (dma_mapping_error(dev, dma_addr)) {
dev_err(dev, "Trying to %s invalid mapping\n", where);
return NULL;
}
return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
}
static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
{
if (!dev || !dev->archdata.dmabounce)
return 0;
if (dev->dma_mask) {
unsigned long limit, mask = *dev->dma_mask;
limit = (mask + 1) & ~mask;
if (limit && size > limit) {
dev_err(dev, "DMA mapping too big (requested %#x "
"mask %#Lx)\n", size, *dev->dma_mask);
return -E2BIG;
}
/* Figure out if we need to bounce from the DMA mask. */
if ((dma_addr | (dma_addr + size - 1)) & ~mask)
return 1;
}
return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
}
static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
enum dma_data_direction dir)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
struct safe_buffer *buf;
if (device_info)
DO_STATS ( device_info->map_op_count++ );
buf = alloc_safe_buffer(device_info, ptr, size, dir);
if (buf == NULL) {
dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
__func__, ptr);
return DMA_ERROR_CODE;
}
dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
__func__, buf->ptr, virt_to_dma(dev, buf->ptr),
buf->safe, buf->safe_dma_addr);
if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
__func__, ptr, buf->safe, size);
memcpy(buf->safe, ptr, size);
}
return buf->safe_dma_addr;
}
static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
size_t size, enum dma_data_direction dir)
{
BUG_ON(buf->size != size);
BUG_ON(buf->direction != dir);
dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
__func__, buf->ptr, virt_to_dma(dev, buf->ptr),
buf->safe, buf->safe_dma_addr);
DO_STATS(dev->archdata.dmabounce->bounce_count++);
if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
void *ptr = buf->ptr;
dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
__func__, buf->safe, ptr, size);
memcpy(ptr, buf->safe, size);
/*
* Since we may have written to a page cache page,
* we need to ensure that the data will be coherent
* with user mappings.
*/
__cpuc_flush_dcache_area(ptr, size);
}
free_safe_buffer(dev->archdata.dmabounce, buf);
}
/* ************************************************** */
/*
* see if a buffer address is in an 'unsafe' range. if it is
* allocate a 'safe' buffer and copy the unsafe buffer into it.
* substitute the safe buffer for the unsafe one.
* (basically move the buffer from an unsafe area to a safe one)
*/
static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs)
{
dma_addr_t dma_addr;
int ret;
dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
__func__, page, offset, size, dir);
dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
ret = needs_bounce(dev, dma_addr, size);
if (ret < 0)
return DMA_ERROR_CODE;
if (ret == 0) {
arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
return dma_addr;
}
if (PageHighMem(page)) {
dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
return DMA_ERROR_CODE;
}
return map_single(dev, page_address(page) + offset, size, dir);
}
/*
* see if a mapped address was really a "safe" buffer and if so, copy
* the data from the safe buffer back to the unsafe buffer and free up
* the safe buffer. (basically return things back to the way they
* should be)
*/
static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
enum dma_data_direction dir, struct dma_attrs *attrs)
{
struct safe_buffer *buf;
dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
__func__, dma_addr, size, dir);
buf = find_safe_buffer_dev(dev, dma_addr, __func__);
if (!buf) {
arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
return;
}
unmap_single(dev, buf, size, dir);
}
static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
size_t sz, enum dma_data_direction dir)
{
struct safe_buffer *buf;
unsigned long off;
dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
__func__, addr, sz, dir);
buf = find_safe_buffer_dev(dev, addr, __func__);
if (!buf)
return 1;
off = addr - buf->safe_dma_addr;
BUG_ON(buf->direction != dir);
dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
buf->safe, buf->safe_dma_addr);
DO_STATS(dev->archdata.dmabounce->bounce_count++);
if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
__func__, buf->safe + off, buf->ptr + off, sz);
memcpy(buf->ptr + off, buf->safe + off, sz);
}
return 0;
}
static void dmabounce_sync_for_cpu(struct device *dev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
return;
arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
}
static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
size_t sz, enum dma_data_direction dir)
{
struct safe_buffer *buf;
unsigned long off;
dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
__func__, addr, sz, dir);
buf = find_safe_buffer_dev(dev, addr, __func__);
if (!buf)
return 1;
off = addr - buf->safe_dma_addr;
BUG_ON(buf->direction != dir);
dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
buf->safe, buf->safe_dma_addr);
DO_STATS(dev->archdata.dmabounce->bounce_count++);
if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
__func__,buf->ptr + off, buf->safe + off, sz);
memcpy(buf->safe + off, buf->ptr + off, sz);
}
return 0;
}
static void dmabounce_sync_for_device(struct device *dev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
if (!__dmabounce_sync_for_device(dev, handle, size, dir))
return;
arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
}
static int dmabounce_set_mask(struct device *dev, u64 dma_mask)
{
if (dev->archdata.dmabounce)
return 0;
return arm_dma_ops.set_dma_mask(dev, dma_mask);
}
static struct dma_map_ops dmabounce_ops = {
.alloc = arm_dma_alloc,
.free = arm_dma_free,
.mmap = arm_dma_mmap,
.get_sgtable = arm_dma_get_sgtable,
.map_page = dmabounce_map_page,
.unmap_page = dmabounce_unmap_page,
.sync_single_for_cpu = dmabounce_sync_for_cpu,
.sync_single_for_device = dmabounce_sync_for_device,
.map_sg = arm_dma_map_sg,
.unmap_sg = arm_dma_unmap_sg,
.sync_sg_for_cpu = arm_dma_sync_sg_for_cpu,
.sync_sg_for_device = arm_dma_sync_sg_for_device,
.set_dma_mask = dmabounce_set_mask,
};
static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
const char *name, unsigned long size)
{
pool->size = size;
DO_STATS(pool->allocs = 0);
pool->pool = dma_pool_create(name, dev, size,
0 /* byte alignment */,
0 /* no page-crossing issues */);
return pool->pool ? 0 : -ENOMEM;
}
int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
unsigned long large_buffer_size,
int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
{
struct dmabounce_device_info *device_info;
int ret;
device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
if (!device_info) {
dev_err(dev,
"Could not allocated dmabounce_device_info\n");
return -ENOMEM;
}
ret = dmabounce_init_pool(&device_info->small, dev,
"small_dmabounce_pool", small_buffer_size);
if (ret) {
dev_err(dev,
"dmabounce: could not allocate DMA pool for %ld byte objects\n",
small_buffer_size);
goto err_free;
}
if (large_buffer_size) {
ret = dmabounce_init_pool(&device_info->large, dev,
"large_dmabounce_pool",
large_buffer_size);
if (ret) {
dev_err(dev,
"dmabounce: could not allocate DMA pool for %ld byte objects\n",
large_buffer_size);
goto err_destroy;
}
}
device_info->dev = dev;
INIT_LIST_HEAD(&device_info->safe_buffers);
rwlock_init(&device_info->lock);
device_info->needs_bounce = needs_bounce_fn;
#ifdef STATS
device_info->total_allocs = 0;
device_info->map_op_count = 0;
device_info->bounce_count = 0;
device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
#endif
dev->archdata.dmabounce = device_info;
set_dma_ops(dev, &dmabounce_ops);
dev_info(dev, "dmabounce: registered device\n");
return 0;
err_destroy:
dma_pool_destroy(device_info->small.pool);
err_free:
kfree(device_info);
return ret;
}
EXPORT_SYMBOL(dmabounce_register_dev);
void dmabounce_unregister_dev(struct device *dev)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
dev->archdata.dmabounce = NULL;
set_dma_ops(dev, NULL);
if (!device_info) {
dev_warn(dev,
"Never registered with dmabounce but attempting"
"to unregister!\n");
return;
}
if (!list_empty(&device_info->safe_buffers)) {
dev_err(dev,
"Removing from dmabounce with pending buffers!\n");
BUG();
}
if (device_info->small.pool)
dma_pool_destroy(device_info->small.pool);
if (device_info->large.pool)
dma_pool_destroy(device_info->large.pool);
#ifdef STATS
if (device_info->attr_res == 0)
device_remove_file(dev, &dev_attr_dmabounce_stats);
#endif
kfree(device_info);
dev_info(dev, "dmabounce: device unregistered\n");
}
EXPORT_SYMBOL(dmabounce_unregister_dev);
MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
MODULE_LICENSE("GPL");