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|
/*
* 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 &&
|