/*
* 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 two global lists, dma_device_list and dma_client_list.
* Both of these are protected by a mutex, dma_list_mutex.
*
* 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.
*
* Each client is responsible for keeping track of the channels it uses. See
* the definition of dma_event_callback in dmaengine.h.
*
* Each device has a kref, which is initialized to 1 when the device is
* registered. A kref_get is done for each class_device registered. When the
* class_device is released, the coresponding kref_put is done in the release
* method. Every time one of the device's channels is allocated to a client,
* a kref_get occurs. When the channel is freed, the coresponding kref_put
* happens. The device's release function does a completion, so
* unregister_device does a remove event, class_device_unregister, a kref_put
* for the first reference, then waits on the completion for all other
* references to finish.
*
* Each channel has an open-coded implementation of Rusty Russell's "bigref,"
* with a kref and a per_cpu local_t. A dma_chan_get is called when a client
* signals that it wants to use a channel, and dma_chan_put is called when
* a channel is removed or a client using it is unregesitered. A client can
* take extra references per outstanding transaction, as is the case with
* the NET DMA client. The release function does a kref_put on the device.
* -ChrisL, DanW
*/
#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>
static DEFINE_MUTEX(dma_list_mutex);
static LIST_HEAD(dma_device_list);
static LIST_HEAD(dma_client_list);
/* --- sysfs implementation --- */
static ssize_t show_memcpy_count(struct class_device *cd, char *buf)
{
struct dma_chan *chan = container_of(cd, struct dma_chan, class_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 class_device *cd, char *buf)
{
struct dma_chan *chan = container_of(cd, struct dma_chan, class_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 class_device *cd, char *buf)
{
struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
int in_use = 0;
if (unlikely(chan->slow_ref) &&
atomic_read(&chan->refcount.refcount) > 1)
in_use = 1;
else {
if (local_read(&(per_cpu_ptr(chan->local,
get_cpu())->refcount)) > 0)
in_use = 1;
put_cpu();
}
return sprintf(buf, "%d\n", in_use);
}
static struct class_device_attribute dma_class_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 void dma_async_device_cleanup(struct kref *kref);
static void dma_class_dev_release(struct class_device *cd)
{
struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
kref_put(&chan->device->refcount, dma_async_device_cleanup);
}
static struct class dma_devclass = {
.name = "dma",
.class_dev_attrs = dma_class_attrs,
.release = dma_class_dev_release,
};
/* --- client and device registration --- */
#define dma_chan_satisfies_mask(chan, mask) \
__dma_chan_satisfies_mask((chan), &(mask))
static int
__dma_chan_satisfies_mask(struct dma_chan *chan, dma_cap_mask_t *want)
{
dma_cap_mask_t has;
bitmap_and(has.bits, want->bits, chan->device->cap_mask.bits,
DMA_TX_TYPE_END);
return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
}
/**
* dma_client_chan_alloc - try to allocate channels to a client
* @client: &dma_client
*
* Called with dma_list_mutex held.
*/
static void dma_client_chan_alloc(struct dma_client *client)
{
struct dma_device *device;
struct dma_chan *chan;
int desc; /* allocated descriptor count */
enum dma_state_client ack;
/* Find a channel */
list_for_each_entry(device, &dma_device_list, global_node)
list_for_each_entry(chan, &device->channels, device_node) {
if (!dma_chan_satisfies_mask(chan, client->cap_mask))
continue;
desc = chan->device->device_alloc_chan_resources(chan);
if (desc >= 0) {
ack = client->event_callback(client,
chan,
DMA_RESOURCE_AVAILABLE);
/* we are done once this client rejects
* an available resource
*/
if (ack == DMA_ACK) {
dma_chan_get(chan);
kref_get(&device->refcount);
} else if (ack == DMA_NAK)
return;
}
}
}
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_chan_cleanup - release a DMA channel's resources
* @kref: kernel reference structure that contains the DMA channel device
*/
void dma_chan_cleanup(struct kref *kref)
{
struct dma_chan *chan = container_of(kref, struct dma_chan, refcount);
chan->device->device_free_chan_resources(chan);
kref_put(&chan->device->refcount, dma_async_device_cleanup);
}
EXPORT_SYMBOL(dma_chan_cleanup);
static void dma_chan_free_rcu(struct rcu_head *rcu)
{
struct dma_chan *chan = container_of(rcu, struct dma_chan, rcu);
int bias = 0x7FFFFFFF;
int i;
for_each_possible_cpu(i)
bias -= local_read(&per_cpu_ptr(chan->local, i)->refcount);
atomic_sub(bias, &chan->refcount.refcount);
kref_put(&chan->refcount, dma_chan_cleanup);
}
static void dma_chan_release(struct dma_chan *chan)
{
atomic_add(0x7FFFFFFF, &chan->refcount.refcount);
chan->slow_ref = 1;
call_rcu(&chan->rcu, dma_chan_free_rcu);
}
/**
* dma_chans_notify_available - broadcast available channels to the clients
*/
static void dma_clients_notify_available(void)
{
struct dma_client *client;
mutex_lock(&dma_list_mutex);
list_for_each_entry(client, &dma_client_list, global_node)
dma_client_chan_alloc(client);
mutex_unlock(&dma_list_mutex);
}
/**
* dma_chans_notify_available - tell the clients that a channel is going away
* @chan: channel on its way out
*/
static void dma_clients_notify_removed(struct dma_chan *chan)
{
struct dma_client *client;
enum dma_state_client ack;
mutex_lock(&dma_list_mutex);
list_for_each_entry(client, &dma_client_list, global_node) {
ack = client->event_callback(client, chan,
DMA_RESOURCE_REMOVED);
/* client was holding resources for this channel so
* free it
*/
if (ack == DMA_ACK) {
dma_chan_put(chan);
kref_put(&chan->device->refcount,
dma_async_device_cleanup);
}
}
mutex_unlock(&dma_list_mutex);
}
/**
* dma_async_client_register - register a &dma_client
* @client: ptr to a client structure with valid 'event_callback' and 'cap_mask'
*/
void dma_async_client_register(struct dma_client *client)
{
mutex_lock(&dma_list_mutex);
list_add_tail(&client->global_node, &dma_client_list);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dma_async_client_register);
/**
* dma_async_client_unregister - unregister a client and free the &dma_client
* @client: &dma_client to free
*
* Force frees any allocated DMA channels, frees the &dma_client memory
*/
void dma_async_client_unregister(struct dma_client *client)
{
struct dma_device *device;
struct dma_chan *chan;
enum dma_state_client ack;
if (!client)
return;
mutex_lock(&dma_list_mutex);
/* free all channels the client is holding */
list_for_each_entry(device, &dma_device_list, global_node)
list_for_each_entry(chan, &device->channels, device_node) {
ack = client->event_callback(client, chan,
DMA_RESOURCE_REMOVED);
if (ack == DMA_ACK) {
dma_chan_put(chan);
kref_put(&chan->device->refcount,
dma_async_device_cleanup);
}
}
list_del(&client->global_node);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dma_async_client_unregister);
/**
* dma_async_client_chan_request - send all available channels to the
* client that satisfy the capability mask
* @client - requester
*/
void dma_async_client_chan_request(struct dma_client *client)
{
mutex_lock(&dma_list_mutex);
dma_client_chan_alloc(client);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dma_async_client_chan_request);
/**
* 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_ZERO_SUM, device->cap_mask) &&
!device->device_prep_dma_interrupt);
BUG_ON(!device->device_alloc_chan_resources);
BUG_ON(!device->device_free_chan_resources);
BUG_ON(!device->device_dependency_added);
BUG_ON(!device->device_is_tx_complete);
BUG_ON(!device->device_issue_pending);
BUG_ON(!device->dev);
init_completion(&device->done);
kref_init(&device->refcount);
device->dev_id = id++;
/* 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->class_dev.class = &dma_devclass;
chan->class_dev.dev = NULL;
snprintf(chan->class_dev.class_id, BUS_ID_SIZE, "dma%dchan%d",
device->dev_id, chan->chan_id);
rc = class_device_register(&chan->class_dev);
if (rc) {
chancnt--;
free_percpu(chan->local);
chan->local = NULL;
goto err_out;
}
kref_get(&device->refcount);
kref_init(&chan->refcount);
chan->slow_ref = 0;
INIT_RCU_HEAD(&chan->rcu);
}
mutex_lock(&dma_list_mutex);
list_add_tail(&device->global_node, &dma_device_list);
mutex_unlock(&dma_list_mutex);
dma_clients_notify_available();
return 0;
err_out:
list_for_each_entry(chan, &device->channels, device_node) {
if (chan->local == NULL)
continue;
kref_put(&device->refcount, dma_async_device_cleanup);
class_device_unregister(&chan->class_dev);
chancnt--;
free_percpu(chan->local);
}
return rc;
}
EXPORT_SYMBOL(dma_async_device_register);
/**
* dma_async_device_cleanup - function called when all references are released
* @kref: kernel reference object
*/
static void dma_async_device_cleanup(struct kref *kref)
{
struct dma_device *device;
device = container_of(kref, struct dma_device, refcount);
complete(&device->done);
}
/**
* dma_async_device_unregister - unregisters DMA devices
* @device: &dma_device
*/
void dma_async_device_unregister(struct dma_device *device)
{
struct dma_chan *chan;
mutex_lock(&dma_list_mutex);
list_del(&device->global_node);
mutex_unlock(&dma_list_mutex);
list_for_each_entry(chan, &device->channels, device_node) {
dma_clients_notify_removed(chan);
class_device_unregister(&chan->class_dev);
dma_chan_release(chan);
}
kref_put(&device->refcount, dma_async_device_cleanup);
wait_for_completion(&device->done);
}
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 addr;
dma_cookie_t cookie;
int cpu;
tx = dev->device_prep_dma_memcpy(chan, len, 0);
if (!tx)
return -ENOMEM;
tx->ack = 1;
tx->callback = NULL;
addr = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
tx->tx_set_src(addr, tx, 0);
addr = dma_map_single(dev->dev, dest, len, DMA_FROM_DEVICE);
tx->tx_set_dest(addr, tx, 0);
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 addr;
dma_cookie_t cookie;
int cpu;
tx = dev->device_prep_dma_memcpy(chan, len, 0);
if (!tx)
return -ENOMEM;
tx->ack = 1;
tx->callback = NULL;
addr = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
tx->tx_set_src(addr, tx, 0);
addr = dma_map_page(dev->dev, page, offset, len, DMA_FROM_DEVICE);
tx->tx_set_dest(addr, tx, 0);
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 addr;
dma_cookie_t cookie;
int cpu;
tx = dev->device_prep_dma_memcpy(chan, len, 0);
if (!tx)
return -ENOMEM;
tx->ack = 1;
tx->callback = NULL;
addr = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
tx->tx_set_src(addr, tx, 0);
addr = dma_map_page(dev->dev, dest_pg, dest_off, len, DMA_FROM_DEVICE);
tx->tx_set_dest(addr, tx, 0);
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);
INIT_LIST_HEAD(&tx->depend_node);
INIT_LIST_HEAD(&tx->depend_list);
}
EXPORT_SYMBOL(dma_async_tx_descriptor_init);
static int __init dma_bus_init(void)
{
mutex_init(&dma_list_mutex);
return class_register(&dma_devclass);
}
subsys_initcall(dma_bus_init);
