blob: aecc6c3f908fd2dd5a79e31a847d1c9cd1cc2568 [file] [log] [blame]
/*
* 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/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;
};
#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) {
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 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;
dma_addr_t dma_addr;
int needs_bounce = 0;
if (device_info)
DO_STATS ( device_info->map_op_count++ );
dma_addr = virt_to_dma(dev, ptr);
if (dev->dma_mask) {
unsigned long mask = *dev->dma_mask;
unsigned long limit;
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 ~0;
}
/*
* Figure out if we need to bounce from the DMA mask.
*/
needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
}
if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
struct safe_buffer *buf;
buf = alloc_safe_buffer(device_info, ptr, size, dir);
if (buf == 0) {
dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
__func__, ptr);
return 0;
}
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);
}
ptr = buf->safe;
dma_addr = buf->safe_dma_addr;
} else {
/*
* We don't need to sync the DMA buffer since
* it was allocated via the coherent allocators.
*/
dma_cache_maint(ptr, size, dir);
}
return dma_addr;
}
static inline void
unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
enum dma_data_direction dir)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
struct safe_buffer *buf = NULL;
/*
* Trying to unmap an invalid mapping
*/
if (dma_mapping_error(dev, dma_addr)) {
dev_err(dev, "Trying to unmap invalid mapping\n");
return;
}
if (device_info)
buf = find_safe_buffer(device_info, dma_addr);
if (buf) {
BUG_ON(buf->size != size);
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 ( device_info->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);
/*
* DMA buffers must have the same cache properties
* as if they were really used for DMA - which means
* data must be written back to RAM. Note that
* we don't use dmac_flush_range() here for the
* bidirectional case because we know the cache
* lines will be coherent with the data written.
*/
dmac_clean_range(ptr, ptr + size);
outer_clean_range(__pa(ptr), __pa(ptr) + size);
}
free_safe_buffer(device_info, buf);
}
}
static int sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
enum dma_data_direction dir)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
struct safe_buffer *buf = NULL;
if (device_info)
buf = find_safe_buffer(device_info, dma_addr);
if (buf) {
/*
* Both of these checks from original code need to be
* commented out b/c some drivers rely on the following:
*
* 1) Drivers may map a large chunk of memory into DMA space
* but only sync a small portion of it. Good example is
* allocating a large buffer, mapping it, and then
* breaking it up into small descriptors. No point
* in syncing the whole buffer if you only have to
* touch one descriptor.
*
* 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
* usually only synced in one dir at a time.
*
* See drivers/net/eepro100.c for examples of both cases.
*
* -ds
*
* 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 ( device_info->bounce_count++ );
switch (dir) {
case DMA_FROM_DEVICE:
dev_dbg(dev,
"%s: copy back safe %p to unsafe %p size %d\n",
__func__, buf->safe, buf->ptr, size);
memcpy(buf->ptr, buf->safe, size);
break;
case DMA_TO_DEVICE:
dev_dbg(dev,
"%s: copy out unsafe %p to safe %p, size %d\n",
__func__,buf->ptr, buf->safe, size);
memcpy(buf->safe, buf->ptr, size);
break;
case DMA_BIDIRECTIONAL:
BUG(); /* is this allowed? what does it mean? */
default:
BUG();
}
/*
* No need to sync the safe buffer - it was allocated
* via the coherent allocators.
*/
return 0;
} else {
return 1;
}
}
/* ************************************************** */
/*
* 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)
*/
dma_addr_t
dma_map_single(struct device *dev, void *ptr, size_t size,
enum dma_data_direction dir)
{
dma_addr_t dma_addr;
dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
__func__, ptr, size, dir);
BUG_ON(dir == DMA_NONE);
dma_addr = map_single(dev, ptr, size, dir);
return dma_addr;
}
/*
* 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)
*/
void
dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
enum dma_data_direction dir)
{
dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
__func__, (void *) dma_addr, size, dir);
BUG_ON(dir == DMA_NONE);
unmap_single(dev, dma_addr, size, dir);
}
int
dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction dir)
{
int i;
dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
__func__, sg, nents, dir);
BUG_ON(dir == DMA_NONE);
for (i = 0; i < nents; i++, sg++) {
struct page *page = sg_page(sg);
unsigned int offset = sg->offset;
unsigned int length = sg->length;
void *ptr = page_address(page) + offset;
sg->dma_address =
map_single(dev, ptr, length, dir);
}
return nents;
}
void
dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction dir)
{
int i;
dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
__func__, sg, nents, dir);
BUG_ON(dir == DMA_NONE);
for (i = 0; i < nents; i++, sg++) {
dma_addr_t dma_addr = sg->dma_address;
unsigned int length = sg->length;
unmap_single(dev, dma_addr, length, dir);
}
}
void dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t dma_addr,
unsigned long offset, size_t size,
enum dma_data_direction dir)
{
dev_dbg(dev, "%s(dma=%#x,off=%#lx,size=%zx,dir=%x)\n",
__func__, dma_addr, offset, size, dir);
if (sync_single(dev, dma_addr, offset + size, dir))
dma_cache_maint(dma_to_virt(dev, dma_addr) + offset, size, dir);
}
EXPORT_SYMBOL(dma_sync_single_range_for_cpu);
void dma_sync_single_range_for_device(struct device *dev, dma_addr_t dma_addr,
unsigned long offset, size_t size,
enum dma_data_direction dir)
{
dev_dbg(dev, "%s(dma=%#x,off=%#lx,size=%zx,dir=%x)\n",
__func__, dma_addr, offset, size, dir);
if (sync_single(dev, dma_addr, offset + size, dir))
dma_cache_maint(dma_to_virt(dev, dma_addr) + offset, size, dir);
}
EXPORT_SYMBOL(dma_sync_single_range_for_device);
void
dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction dir)
{
int i;
dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
__func__, sg, nents, dir);
BUG_ON(dir == DMA_NONE);
for (i = 0; i < nents; i++, sg++) {
dma_addr_t dma_addr = sg->dma_address;
unsigned int length = sg->length;
sync_single(dev, dma_addr, length, dir);
}
}
void
dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction dir)
{
int i;
dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
__func__, sg, nents, dir);
BUG_ON(dir == DMA_NONE);
for (i = 0; i < nents; i++, sg++) {
dma_addr_t dma_addr = sg->dma_address;
unsigned int length = sg->length;
sync_single(dev, dma_addr, length, dir);
}
}
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)
{
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);
#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;
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;
}
void
dmabounce_unregister_dev(struct device *dev)
{
struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
dev->archdata.dmabounce = 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(dma_map_single);
EXPORT_SYMBOL(dma_unmap_single);
EXPORT_SYMBOL(dma_map_sg);
EXPORT_SYMBOL(dma_unmap_sg);
EXPORT_SYMBOL(dma_sync_sg_for_cpu);
EXPORT_SYMBOL(dma_sync_sg_for_device);
EXPORT_SYMBOL(dmabounce_register_dev);
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");