Commit c13c8260 authored by Chris Leech's avatar Chris Leech Committed by David S. Miller

[I/OAT]: DMA memcpy subsystem

Provides an API for offloading memory copies to DMA devices
Signed-off-by: default avatarChris Leech <christopher.leech@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 427abfa2
......@@ -72,4 +72,6 @@ source "drivers/edac/Kconfig"
source "drivers/rtc/Kconfig"
source "drivers/dma/Kconfig"
endmenu
......@@ -74,3 +74,4 @@ obj-$(CONFIG_SGI_SN) += sn/
obj-y += firmware/
obj-$(CONFIG_CRYPTO) += crypto/
obj-$(CONFIG_SUPERH) += sh/
obj-$(CONFIG_DMA_ENGINE) += dma/
#
# DMA engine configuration
#
menu "DMA Engine support"
config DMA_ENGINE
bool "Support for DMA engines"
---help---
DMA engines offload copy operations from the CPU to dedicated
hardware, allowing the copies to happen asynchronously.
endmenu
obj-y += dmaengine.o
/*
* 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 has a channels list, it's only modified under the client->lock
* and in an RCU callback, so it's safe to read under rcu_read_lock().
*
* Each device has a kref, which is initialized to 1 when the device is
* registered. A kref_put 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 single reference is set when on an
* ADDED event, and removed with a REMOVE event. Net DMA client takes an
* extra reference per outstanding transaction. The relase function does a
* kref_put on the device. -ChrisL
*/
#include <linux/init.h>
#include <linux/module.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>
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_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_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);
return sprintf(buf, "%d\n", (chan->client ? 1 : 0));
}
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 --- */
/**
* dma_client_chan_alloc - try to allocate a channel to a client
* @client: &dma_client
*
* Called with dma_list_mutex held.
*/
static struct dma_chan *dma_client_chan_alloc(struct dma_client *client)
{
struct dma_device *device;
struct dma_chan *chan;
unsigned long flags;
int desc; /* allocated descriptor count */
/* Find a channel, any DMA engine will do */
list_for_each_entry(device, &dma_device_list, global_node) {
list_for_each_entry(chan, &device->channels, device_node) {
if (chan->client)
continue;
desc = chan->device->device_alloc_chan_resources(chan);
if (desc >= 0) {
kref_get(&device->refcount);
kref_init(&chan->refcount);
chan->slow_ref = 0;
INIT_RCU_HEAD(&chan->rcu);
chan->client = client;
spin_lock_irqsave(&client->lock, flags);
list_add_tail_rcu(&chan->client_node,
&client->channels);
spin_unlock_irqrestore(&client->lock, flags);
return chan;
}
}
}
return NULL;
}
/**
* dma_client_chan_free - release a DMA channel
* @chan: &dma_chan
*/
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);
chan->client = NULL;
kref_put(&chan->device->refcount, dma_async_device_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_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_client_chan_free(struct dma_chan *chan)
{
atomic_add(0x7FFFFFFF, &chan->refcount.refcount);
chan->slow_ref = 1;
call_rcu(&chan->rcu, dma_chan_free_rcu);
}
/**
* dma_chans_rebalance - reallocate channels to clients
*
* When the number of DMA channel in the system changes,
* channels need to be rebalanced among clients
*/
static void dma_chans_rebalance(void)
{
struct dma_client *client;
struct dma_chan *chan;
unsigned long flags;
mutex_lock(&dma_list_mutex);
list_for_each_entry(client, &dma_client_list, global_node) {
while (client->chans_desired > client->chan_count) {
chan = dma_client_chan_alloc(client);
if (!chan)
break;
client->chan_count++;
client->event_callback(client,
chan,
DMA_RESOURCE_ADDED);
}
while (client->chans_desired < client->chan_count) {
spin_lock_irqsave(&client->lock, flags);
chan = list_entry(client->channels.next,
struct dma_chan,
client_node);
list_del_rcu(&chan->client_node);
spin_unlock_irqrestore(&client->lock, flags);
client->chan_count--;
client->event_callback(client,
chan,
DMA_RESOURCE_REMOVED);
dma_client_chan_free(chan);
}
}
mutex_unlock(&dma_list_mutex);
}
/**
* dma_async_client_register - allocate and register a &dma_client
* @event_callback: callback for notification of channel addition/removal
*/
struct dma_client *dma_async_client_register(dma_event_callback event_callback)
{
struct dma_client *client;
client = kzalloc(sizeof(*client), GFP_KERNEL);
if (!client)
return NULL;
INIT_LIST_HEAD(&client->channels);
spin_lock_init(&client->lock);
client->chans_desired = 0;
client->chan_count = 0;
client->event_callback = event_callback;
mutex_lock(&dma_list_mutex);
list_add_tail(&client->global_node, &dma_client_list);
mutex_unlock(&dma_list_mutex);
return client;
}
/**
* dma_async_client_unregister - unregister a client and free the &dma_client
* @client:
*
* Force frees any allocated DMA channels, frees the &dma_client memory
*/
void dma_async_client_unregister(struct dma_client *client)
{
struct dma_chan *chan;
if (!client)
return;
rcu_read_lock();
list_for_each_entry_rcu(chan, &client->channels, client_node)
dma_client_chan_free(chan);
rcu_read_unlock();
mutex_lock(&dma_list_mutex);
list_del(&client->global_node);
mutex_unlock(&dma_list_mutex);
kfree(client);
dma_chans_rebalance();
}
/**
* dma_async_client_chan_request - request DMA channels
* @client: &dma_client
* @number: count of DMA channels requested
*
* Clients call dma_async_client_chan_request() to specify how many
* DMA channels they need, 0 to free all currently allocated.
* The resulting allocations/frees are indicated to the client via the
* event callback.
*/
void dma_async_client_chan_request(struct dma_client *client,
unsigned int number)
{
client->chans_desired = number;
dma_chans_rebalance();
}
/**
* dma_async_device_register -
* @device: &dma_device
*/
int dma_async_device_register(struct dma_device *device)
{
static int id;
int chancnt = 0;
struct dma_chan* chan;
if (!device)
return -ENODEV;
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);
kref_get(&device->refcount);
class_device_register(&chan->class_dev);
}
mutex_lock(&dma_list_mutex);
list_add_tail(&device->global_node, &dma_device_list);
mutex_unlock(&dma_list_mutex);
dma_chans_rebalance();
return 0;
}
/**
* dma_async_device_unregister -
* @device: &dma_device
*/
static void dma_async_device_cleanup(struct kref *kref)
{
struct dma_device *device;
device = container_of(kref, struct dma_device, refcount);
complete(&device->done);
}
void dma_async_device_unregister(struct dma_device* device)
{
struct dma_chan *chan;
unsigned long flags;
mutex_lock(&dma_list_mutex);
list_del(&device->global_node);
mutex_unlock(&dma_list_mutex);
list_for_each_entry(chan, &device->channels, device_node) {
if (chan->client) {
spin_lock_irqsave(&chan->client->lock, flags);
list_del(&chan->client_node);
chan->client->chan_count--;
spin_unlock_irqrestore(&chan->client->lock, flags);
chan->client->event_callback(chan->client,
chan,
DMA_RESOURCE_REMOVED);
dma_client_chan_free(chan);
}
class_device_unregister(&chan->class_dev);
}
dma_chans_rebalance();
kref_put(&device->refcount, dma_async_device_cleanup);
wait_for_completion(&device->done);
}
static int __init dma_bus_init(void)
{
mutex_init(&dma_list_mutex);
return class_register(&dma_devclass);
}
subsys_initcall(dma_bus_init);
EXPORT_SYMBOL(dma_async_client_register);
EXPORT_SYMBOL(dma_async_client_unregister);
EXPORT_SYMBOL(dma_async_client_chan_request);
EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf);
EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg);
EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg);
EXPORT_SYMBOL(dma_async_memcpy_complete);
EXPORT_SYMBOL(dma_async_memcpy_issue_pending);
EXPORT_SYMBOL(dma_async_device_register);
EXPORT_SYMBOL(dma_async_device_unregister);
EXPORT_SYMBOL(dma_chan_cleanup);
/*
* 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.
*/
#ifndef DMAENGINE_H
#define DMAENGINE_H
#include <linux/config.h>
#ifdef CONFIG_DMA_ENGINE
#include <linux/device.h>
#include <linux/uio.h>
#include <linux/kref.h>
#include <linux/completion.h>
#include <linux/rcupdate.h>
/**
* enum dma_event - resource PNP/power managment events
* @DMA_RESOURCE_SUSPEND: DMA device going into low power state
* @DMA_RESOURCE_RESUME: DMA device returning to full power
* @DMA_RESOURCE_ADDED: DMA device added to the system
* @DMA_RESOURCE_REMOVED: DMA device removed from the system
*/
enum dma_event {
DMA_RESOURCE_SUSPEND,
DMA_RESOURCE_RESUME,
DMA_RESOURCE_ADDED,
DMA_RESOURCE_REMOVED,
};
/**
* typedef dma_cookie_t
*
* if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error code
*/
typedef s32 dma_cookie_t;
#define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)
/**
* enum dma_status - DMA transaction status
* @DMA_SUCCESS: transaction completed successfully
* @DMA_IN_PROGRESS: transaction not yet processed
* @DMA_ERROR: transaction failed
*/
enum dma_status {
DMA_SUCCESS,
DMA_IN_PROGRESS,
DMA_ERROR,
};
/**
* struct dma_chan_percpu - the per-CPU part of struct dma_chan
* @refcount: local_t used for open-coded "bigref" counting
* @memcpy_count: transaction counter
* @bytes_transferred: byte counter
*/
struct dma_chan_percpu {
local_t refcount;
/* stats */
unsigned long memcpy_count;
unsigned long bytes_transferred;
};
/**
* struct dma_chan - devices supply DMA channels, clients use them
* @client: ptr to the client user of this chan, will be NULL when unused
* @device: ptr to the dma device who supplies this channel, always !NULL
* @cookie: last cookie value returned to client
* @chan_id:
* @class_dev:
* @refcount: kref, used in "bigref" slow-mode
* @slow_ref:
* @rcu:
* @client_node: used to add this to the client chan list
* @device_node: used to add this to the device chan list
* @local: per-cpu pointer to a struct dma_chan_percpu
*/
struct dma_chan {
struct dma_client *client;
struct dma_device *device;
dma_cookie_t cookie;
/* sysfs */
int chan_id;
struct class_device class_dev;
struct kref refcount;
int slow_ref;
struct rcu_head rcu;
struct list_head client_node;
struct list_head device_node;
struct dma_chan_percpu *local;
};
void dma_chan_cleanup(struct kref *kref);
static inline void dma_chan_get(struct dma_chan *chan)
{
if (unlikely(chan->slow_ref))
kref_get(&chan->refcount);
else {
local_inc(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
put_cpu();
}
}
static inline void dma_chan_put(struct dma_chan *chan)
{
if (unlikely(chan->slow_ref))
kref_put(&chan->refcount, dma_chan_cleanup);
else {
local_dec(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
put_cpu();
}
}
/*
* typedef dma_event_callback - function pointer to a DMA event callback
*/
typedef void (*dma_event_callback) (struct dma_client *client,
struct dma_chan *chan, enum dma_event event);
/**
* struct dma_client - info on the entity making use of DMA services
* @event_callback: func ptr to call when something happens
* @chan_count: number of chans allocated
* @chans_desired: number of chans requested. Can be +/- chan_count
* @lock: protects access to the channels list
* @channels: the list of DMA channels allocated
* @global_node: list_head for global dma_client_list
*/
struct dma_client {
dma_event_callback event_callback;
unsigned int chan_count;
unsigned int chans_desired;
spinlock_t lock;
struct list_head channels;
struct list_head global_node;
};
/**
* struct dma_device - info on the entity supplying DMA services
* @chancnt: how many DMA channels are supported
* @channels: the list of struct dma_chan
* @global_node: list_head for global dma_device_list
* @refcount:
* @done:
* @dev_id:
* Other func ptrs: used to make use of this device's capabilities
*/
struct dma_device {
unsigned int chancnt;
struct list_head channels;
struct list_head global_node;
struct kref refcount;
struct completion done;
int dev_id;
int (*device_alloc_chan_resources)(struct dma_chan *chan);
void (*device_free_chan_resources)(struct dma_chan *chan);
dma_cookie_t (*device_memcpy_buf_to_buf)(struct dma_chan *chan,
void *dest, void *src, size_t len);
dma_cookie_t (*device_memcpy_buf_to_pg)(struct dma_chan *chan,
struct page *page, unsigned int offset, void *kdata,
size_t len);
dma_cookie_t (*device_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);
enum dma_status (*device_memcpy_complete)(struct dma_chan *chan,
dma_cookie_t cookie, dma_cookie_t *last,
dma_cookie_t *used);
void (*device_memcpy_issue_pending)(struct dma_chan *chan);
};
/* --- public DMA engine API --- */
struct dma_client *dma_async_client_register(dma_event_callback event_callback);
void dma_async_client_unregister(struct dma_client *client);
void dma_async_client_chan_request(struct dma_client *client,
unsigned int number);
/**
* 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)
*/
static inline dma_cookie_t dma_async_memcpy_buf_to_buf(struct dma_chan *chan,