/*
* Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
*
* 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.
*
* 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, write to the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* The full GNU General Public License is included in this distribution in the
* file called COPYING.
*/
/*
* This code implements the DMA subsystem. It provides a HW-neutral interface
* for other kernel code to use asynchronous memory copy capabilities,
* if present, and allows different HW DMA drivers to register as providing
* this capability.
*
* Due to the fact we are accelerating what is already a relatively fast
* operation, the code goes to great lengths to avoid additional overhead,
* such as locking.
*
* LOCKING:
*
* The subsystem keeps a global list of dma_device structs it is protected by a
* mutex, dma_list_mutex.
*
* A subsystem can get access to a channel by calling dmaengine_get() followed
* by dma_find_channel(), or if it has need for an exclusive channel it can call
* dma_request_channel(). Once a channel is allocated a reference is taken
* against its corresponding driver to disable removal.
*
* Each device has a channels list, which runs unlocked but is never modified
* once the device is registered, it's just setup by the driver.
*
* See Documentation/dmaengine.txt for more details
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/hardirq.h>
#include <linux/spinlock.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/jiffies.h>
#include <linux/rculist.h>
static DEFINE_MUTEX(dma_list_mutex);
static LIST_HEAD(dma_device_list);
static long dmaengine_ref_count;
/* --- sysfs implementation --- */
static ssize_t show_memcpy_count(struct device *dev, struct device_attribute *attr, char *buf)
{
struct dma_chan *chan = to_dma_chan(dev);
unsigned long count = 0;
int i;
for_each_possible_cpu(i)
count += per_cpu_ptr(chan->local, i)->memcpy_count;
return sprintf(buf, "%lu\n", count);
}
static ssize_t show_bytes_transferred(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct dma_chan *chan = to_dma_chan(dev);
unsigned long count = 0;
int i;
for_each_possible_cpu(i)
count += per_cpu_ptr(chan->local, i)->bytes_transferred;
return sprintf(buf, "%lu\n", count);
}
static ssize_t show_in_use(struct device *dev, struct device_attribute *attr, char *buf)
{
struct dma_chan *chan = to_dma_chan(dev);
return sprintf(buf, "%d\n", chan->client_count);
}
static struct device_attribute dma_attrs[] = {
__ATTR(memcpy_count, S_IRUGO, show_memcpy_count, NULL),
__ATTR(bytes_transferred, S_IRUGO, show_bytes_transferred, NULL),
__ATTR(in_use, S_IRUGO, show_in_use, NULL),
__ATTR_NULL
};
static struct class dma_devclass = {
.name = "dma",
.dev_attrs = dma_attrs,
};
/* --- client and device registration --- */
#define dma_device_satisfies_mask(device, mask) \
__dma_device_satisfies_mask((device), &(mask))
static int
__dma_device_satisfies_mask(struct dma_device *device, dma_cap_mask_t *want)
{
dma_cap_mask_t has;
bitmap_and(has.bits, want->bits, device->cap_mask.bits,
DMA_TX_TYPE_END);
return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
}
static struct module *dma_chan_to_owner(struct dma_chan *chan)
{
return chan->device->dev->driver->owner;
}
/**
* balance_ref_count - catch up the channel reference count
* @chan - channel to balance ->client_count versus dmaengine_ref_count
*
* balance_ref_count must be called under dma_list_mutex
*/
static void balance_ref_count(struct dma_chan *chan)
{
struct module *owner = dma_chan_to_owner(chan);
while (chan->client_count < dmaengine_ref_count) {
__module_get(owner);
chan->client_count++;
}
}
/**
* dma_chan_get - try to grab a dma channel's parent driver module
* @chan - channel to grab
*
* Must be called under dma_list_mutex
*/
static int dma_chan_get(struct dma_chan *chan)
{
int err = -ENODEV;
struct module *owner = dma_chan_to_owner(chan);
if (chan->client_count) {
__module_get(owner);
err = 0;
} else if (try_module_get(owner))
err = 0;
if (err == 0)
chan->client_count++;
/* allocate upon first client reference */
if (chan->client_count == 1 && err == 0) {
int desc_cnt = chan->device->device_alloc_chan_resources(chan);
if (desc_cnt < 0) {
err = desc_cnt;
chan->client_count = 0;
module_put(owner);
} else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
balance_ref_count(chan);
}
return err;
}
/**
* dma_chan_put - drop a reference to a dma channel's parent driver module
* @chan - channel to release
*
* Must be called under dma_list_mutex
*/
static void dma_chan_put(struct dma_chan *chan)
{
if (!chan->client_count)
return; /* this channel failed alloc_chan_resources */
chan->client_count--;
module_put(dma_chan_to_owner(chan));
if (chan->client_count == 0)
chan->device->device_free_chan_resources(chan);
}
enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
{
enum dma_status status;
unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
dma_async_issue_pending(chan);
do {
status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
printk(KERN_ERR "dma_sync_wait_timeout!\n");
return DMA_ERROR;
}
} while (status == DMA_IN_PROGRESS);
return status;
}
EXPORT_SYMBOL(dma_sync_wait);
/**
* dma_cap_mask_all - enable iteration over all operation types
*/
static dma_cap_mask_t dma_cap_mask_all;
/**
* dma_chan_tbl_ent - tracks channel allocations per core/operation
* @chan - associated channel for this entry
*/
struct dma_chan_tbl_ent {
struct dma_chan *chan;
};
/**
* channel_table - percpu lookup table for memory-to-memory offload providers
*/
static struct dma_chan_tbl_ent *channel_table[DMA_TX_TYPE_END];
static int __init dma_channel_table_init(void)
{
enum dma_transaction_type cap;
int err = 0;
bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
/* 'interrupt', 'private', and 'slave' are channel capabilities,
* but are not associated with an operation so they do not need
* an entry in the channel_table
*/
clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
clear_bit(DMA_PRIVATE, dma_cap_mask_all.bits);
clear_bit(DMA_SLAVE, dma_cap_mask_all.bits);
for_each_dma_cap_mask(cap, dma_cap_mask_all) {
channel_table[cap] = alloc_percpu(struct dma_chan_tbl_ent);
if (!channel_table[cap]) {
err = -ENOMEM;
break;
}
}
if (err) {
pr_err("dmaengine: initialization failure\n");
for_each_dma_cap_mask(cap, dma_cap_mask_all)
if (channel_table[cap])
free_percpu(channel_table[cap]);
}
return err;
}
subsys_initcall(dma_channel_table_init);
/**
* dma_find_channel - find a channel to carry out the operation
* @tx_type: transaction type
*/
struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
{
struct dma_chan *chan;
int cpu;
WARN_ONCE(dmaengine_ref_count == 0,
"client called %s without a reference", __func__);
cpu = get_cpu();
chan = per_cpu_ptr(channel_table[tx_type], cpu)->chan;
put_cpu();
return chan;
}
EXPORT_SYMBOL(dma_find_channel);
/**
* dma_issue_pending_all - flush all pending operations across all channels
*/
void dma_issue_pending_all(void)
{
struct dma_device *device;
struct dma_chan *chan;
WARN_ONCE(dmaengine_ref_count == 0,
"client called %s without a reference", __func__);
rcu_read_lock();
list_for_each_entry_rcu(device, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
if (chan->client_count)
device->device_issue_pending(chan);
}
rcu_read_unlock();
}
EXPORT_SYMBOL(dma_issue_pending_all);
/**
* nth_chan - returns the nth channel of the given capability
* @cap: capability to match
* @n: nth channel desired
*
* Defaults to returning the channel with the desired capability and the
* lowest reference count when 'n' cannot be satisfied. Must be called
* under dma_list_mutex.
*/
static struct dma_chan *nth_chan(enum dma_transaction_type cap, int n)
{
struct dma_device *device;
struct dma_chan *chan;
struct dma_chan *ret = NULL;
struct dma_chan *min = NULL;
list_for_each_entry(device, &dma_device_list, global_node) {
if (!dma_has_cap(cap, device->cap_mask) ||
dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node) {
if (!chan->client_count)
continue;
if (!min)
min = chan;
else if (chan->table_count < min->table_count)
min = chan;
if (n-- == 0) {
ret = chan;
break; /* done */
}
}
if (ret)
break; /* done */
}
if (!ret)
ret = min;
if (ret)
ret->table_count++;
return ret;
}
/**
* dma_channel_rebalance - redistribute the available channels
*
* Optimize for cpu isolation (each cpu gets a dedicated channel for an
* operation type) in the SMP case, and operation isolation (avoid
* multi-tasking channels) in the non-SMP case. Must be called under
* dma_list_mutex.
*/
static void dma_channel_rebalance(void)
{
struct dma_chan *chan;
struct dma_device *device;
int cpu;
int cap;
int n;
/* undo the last distribution */
for_each_dma_cap_mask(cap, dma_cap_mask_all)
for_each_possible_cpu(cpu)
per_cpu_ptr(channel_table[cap], cpu)->chan = NULL;
list_for_each_entry(device, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
chan->table_count = 0;
}
/* don't populate the channel_table if no clients are available */
if (!dmaengine_ref_count)
return;
/* redistribute available channels */
n = 0;
for_each_dma_cap_mask(cap, dma_cap_mask_all)
for_each_online_cpu(cpu) {
if (num_possible_cpus() > 1)
chan = nth_chan(cap, n++);
else
chan = nth_chan(cap, -1);
per_cpu_ptr(channel_table[cap], cpu)->chan = chan;
}
}
static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev)
{
struct dma_chan *chan;
struct dma_chan *ret = NULL;
if (!__dma_device_satisfies_mask(dev, mask)) {
pr_debug("%s: wrong capabilities\n", __func__);
return NULL;
}
/* devices with multiple channels need special handling as we need to
* ensure that all channels are either private or public.
*/
if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask))
list_for_each_entry(chan, &dev->channels, device_node) {
/* some channels are already publicly allocated */
if (chan->client_count)
return NULL;
}
list_for_each_entry(chan, &dev->channels, device_node) {
if (chan->client_count) {
pr_debug("%s: %s busy\n",
__func__, dev_name(&chan->dev));
continue;
}
ret = chan;
break;
}
return ret;
}
/**
* dma_request_channel - try to allocate an exclusive channel
* @mask: capabilities that the channel must satisfy
* @fn: optional callback to disposition available channels
* @fn_param: opaque parameter to pass to dma_filter_fn
*/
struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param)
{
struct dma_device *device, *_d;
struct dma_chan *chan = NULL;
bool ack;
int err;
/* Find a channel */
mutex_lock(&dma_list_mutex);
list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
chan = private_candidate(mask, device);
if (!chan)
continue;
if (fn)
ack = fn(chan, fn_param);
else
ack = true;
if (ack) {
/* Found a suitable channel, try to grab, prep, and
* return it. We first set DMA_PRIVATE to disable
* balance_ref_count as this channel will not be
* published in the general-purpose allocator
*/
dma_cap_set(DMA_PRIVATE, device->cap_mask);
err = dma_chan_get(chan);
if (err == -ENODEV) {
pr_debug("%s: %s module removed\n", __func__,
dev_name(&chan->dev));
list_del_rcu(&device->global_node);
} else if (err)
pr_err("dmaengine: failed to get %s: (%d)\n",
dev_name(&chan->dev), err);
else
break;
} else
pr_debug("%s: %s filter said false\n",
__func__, dev_name(&chan->dev));
chan = NULL;
}
mutex_unlock(&dma_list_mutex);
pr_debug("%s: %s (%s)\n", __func__, chan ? "success" : "fail",
chan ? dev_name(&chan->dev) : NULL);
return chan;
}
EXPORT_SYMBOL_GPL(__dma_request_channel);
void dma_release_channel(struct dma_chan *chan)
{
mutex_lock(&dma_list_mutex);
WARN_ONCE(chan->client_count != 1,
"chan reference count %d != 1\n", chan->client_count);
dma_chan_put(chan);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL_GPL(dma_release_channel);
/**
* dmaengine_get - register interest in dma_channels
*/
void dmaengine_get(void)
{
struct dma_device *device, *_d;
struct dma_chan *chan;
int err;
mutex_lock(&dma_list_mutex);
dmaengine_ref_count++;
/* try to grab channels */
list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node) {
err = dma_chan_get(chan);
if (err == -ENODEV) {
/* module removed before we could use it */
list_del_rcu(&device->global_node);
break;
} else if (err)
pr_err("dmaengine: failed to get %s: (%d)\n",
dev_name(&chan->dev), err);
}
}
/* if this is the first reference and there were channels
* waiting we need to rebalance to get those channels
* incorporated into the channel table
*/
if (dmaengine_ref_count == 1)
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dmaengine_get);
/**
* dmaengine_put - let dma drivers be removed when ref_count == 0
*/
void dmaengine_put(void)
{
struct dma_device *device;
struct dma_chan *chan;
mutex_lock(&dma_list_mutex);
dmaengine_ref_count--;
BUG_ON(dmaengine_ref_count < 0);
/* drop channel references */
list_for_each_entry(device, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
dma_chan_put(chan);
}
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dmaengine_put);
/**
* dma_async_device_register - registers DMA devices found
* @device: &dma_device
*/
int dma_async_device_register(struct dma_device *device)
{
static int id;
int chancnt = 0, rc;
struct dma_chan* chan;
if (!device)
return -ENODEV;
/* validate device routines */
BUG_ON(dma_has_cap(DMA_MEMCPY, device->cap_mask) &&
!device->device_prep_dma_memcpy);
BUG_ON(dma_has_cap(DMA_XOR, device->cap_mask) &&
!device->device_prep_dma_xor);
BUG_ON(dma_has_cap(DMA_ZERO_SUM, device->cap_mask) &&
!device->device_prep_dma_zero_sum);
BUG_ON(dma_has_cap(DMA_MEMSET, device->cap_mask) &&
!device->device_prep_dma_memset);
BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
!device->device_prep_dma_interrupt);
BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
!device->device_prep_slave_sg);
BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
!device->device_terminate_all);
BUG_ON(!device->device_alloc_chan_resources);
BUG_ON(!device->device_free_chan_resources);
BUG_ON(!device->device_is_tx_complete);
BUG_ON(!device->device_issue_pending);
BUG_ON(!device->dev);
mutex_lock(&dma_list_mutex);
device->dev_id = id++;
mutex_unlock(&dma_list_mutex);
/* represent channels in sysfs. Probably want devs too */
list_for_each_entry(chan, &device->channels, device_node) {
chan->local = alloc_percpu(typeof(*chan->local));
if (chan->local == NULL)
continue;
chan->chan_id = chancnt++;
chan->dev.class = &dma_devclass;
chan->dev.parent = device->dev;
dev_set_name(&chan->dev, "dma%dchan%d",
device->dev_id, chan->chan_id);
rc = device_register(&chan->dev);
if (rc) {
free_percpu(chan->local);
chan->local = NULL;
goto err_out;
}
chan->client_count = 0;
}
device->chancnt = chancnt;
mutex_lock(&dma_list_mutex);
/* take references on public channels */
if (dmaengine_ref_count && !dma_has_cap(DMA_PRIVATE, device->cap_mask))
list_for_each_entry(chan, &device->channels, device_node) {
/* if clients are already waiting for channels we need
* to take references on their behalf
*/
if (dma_chan_get(chan) == -ENODEV) {
/* note we can only get here for the first
* channel as the remaining channels are
* guaranteed to get a reference
*/
rc = -ENODEV;
mutex_unlock(&dma_list_mutex);
goto err_out;
}
}
list_add_tail_rcu(&device->global_node, &dma_device_list);
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
return 0;
err_out:
list_for_each_entry(chan, &device->channels, device_node) {
if (chan->local == NULL)
continue;
device_unregister(&chan->dev);
free_percpu(chan->local);
}
return rc;
}
EXPORT_SYMBOL(dma_async_device_register);
/**
* dma_async_device_unregister - unregister a DMA device
* @device: &dma_device
*
* This routine is called by dma driver exit routines, dmaengine holds module
* references to prevent it being called while channels are in use.
*/
void dma_async_device_unregister(struct dma_device *device)
{
struct dma_chan *chan;
mutex_lock(&dma_list_mutex);
list_del_rcu(&device->global_node);
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
list_for_each_entry(chan, &device->channels, device_node) {
WARN_ONCE(chan->client_count,
"%s called while %d clients hold a reference\n",
__func__, chan->client_count);
device_unregister(&chan->dev);
}
}
EXPORT_SYMBOL(dma_async_device_unregister);
/**
* dma_async_memcpy_buf_to_buf - offloaded copy between virtual addresses
* @chan: DMA channel to offload copy to
* @dest: destination address (virtual)
* @src: source address (virtual)
* @len: length
*
* Both @dest and @src must be mappable to a bus address according to the
* DMA mapping API rules for streaming mappings.
* Both @dest and @src must stay memory resident (kernel memory or locked
* user space pages).
*/
dma_cookie_t
dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
void *src, size_t len)
{
struct dma_device *dev = chan->device;
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
dma_dest = dma_map_single(dev->dev, dest, len, DMA_FROM_DEVICE);
tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
DMA_CTRL_ACK);
if (!tx) {
dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
dma_unmap_single(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
return -ENOMEM;
}
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
return cookie;
}
EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf);
/**
* dma_async_memcpy_buf_to_pg - offloaded copy from address to page
* @chan: DMA channel to offload copy to
* @page: destination page
* @offset: offset in page to copy to
* @kdata: source address (virtual)
* @len: length
*
* Both @page/@offset and @kdata must be mappable to a bus address according
* to the DMA mapping API rules for streaming mappings.
* Both @page/@offset and @kdata must stay memory resident (kernel memory or
* locked user space pages)
*/
dma_cookie_t
dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
unsigned int offset, void *kdata, size_t len)
{
struct dma_device *dev = chan->device;
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
dma_src = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
dma_dest = dma_map_page(dev->dev, page, offset, len, DMA_FROM_DEVICE);
tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
DMA_CTRL_ACK);
if (!tx) {
dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
return -ENOMEM;
}
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
return cookie;
}
EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg);
/**
* dma_async_memcpy_pg_to_pg - offloaded copy from page to page
* @chan: DMA channel to offload copy to
* @dest_pg: destination page
* @dest_off: offset in page to copy to
* @src_pg: source page
* @src_off: offset in page to copy from
* @len: length
*
* Both @dest_page/@dest_off and @src_page/@src_off must be mappable to a bus
* address according to the DMA mapping API rules for streaming mappings.
* Both @dest_page/@dest_off and @src_page/@src_off must stay memory resident
* (kernel memory or locked user space pages).
*/
dma_cookie_t
dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
unsigned int dest_off, struct page *src_pg, unsigned int src_off,
size_t len)
{
struct dma_device *dev = chan->device;
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
DMA_FROM_DEVICE);
tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
DMA_CTRL_ACK);
if (!tx) {
dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
return -ENOMEM;
}
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
return cookie;
}
EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg);
void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
struct dma_chan *chan)
{
tx->chan = chan;
spin_lock_init(&tx->lock);
}
EXPORT_SYMBOL(dma_async_tx_descriptor_init);
/* dma_wait_for_async_tx - spin wait for a transaction to complete
* @tx: in-flight transaction to wait on
*
* This routine assumes that tx was obtained from a call to async_memcpy,
* async_xor, async_memset, etc which ensures that tx is "in-flight" (prepped
* and submitted). Walking the parent chain is only meant to cover for DMA
* drivers that do not implement the DMA_INTERRUPT capability and may race with
* the driver's descriptor cleanup routine.
*/
enum dma_status
dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
{
enum dma_status status;
struct dma_async_tx_descriptor *iter;
struct dma_async_tx_descriptor *parent;
if (!tx)
return DMA_SUCCESS;
WARN_ONCE(tx->parent, "%s: speculatively walking dependency chain for"
" %s\n", __func__, dev_name(&tx->chan->dev));
/* poll through the dependency chain, return when tx is complete */
do {
iter = tx;
/* find the root of the unsubmitted dependency chain */
do {
parent = iter->parent;
if (!parent)
break;
else
iter = parent;
} while (parent);
/* there is a small window for ->parent == NULL and
* ->cookie == -EBUSY
*/
while (iter->cookie == -EBUSY)
cpu_relax();
status = dma_sync_wait(iter->chan, iter->cookie);
} while (status == DMA_IN_PROGRESS || (iter != tx));
return status;
}
EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
/* dma_run_dependencies - helper routine for dma drivers to process
* (start) dependent operations on their target channel
* @tx: transaction with dependencies
*/
void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
{
struct dma_async_tx_descriptor *dep = tx->next;
struct dma_async_tx_descriptor *dep_next;
struct dma_chan *chan;
if (!dep)
return;
chan = dep->chan;
/* keep submitting up until a channel switch is detected
* in that case we will be called again as a result of
* processing the interrupt from async_tx_channel_switch
*/
for (; dep; dep = dep_next) {
spin_lock_bh(&dep->lock);
dep->parent = NULL;
dep_next = dep->next;
if (dep_next && dep_next->chan == chan)
dep->next = NULL; /* ->next will be submitted */
else
dep_next = NULL; /* submit current dep and terminate */
spin_unlock_bh(&dep->lock);
dep->tx_submit(dep);
}
chan->device->device_issue_pending(chan);
}
EXPORT_SYMBOL_GPL(dma_run_dependencies);
static int __init dma_bus_init(void)
{
mutex_init(&dma_list_mutex);
return class_register(&dma_devclass);
}
subsys_initcall(dma_bus_init);
