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    Subject[PATCH 1/8] [I/OAT] DMA memcpy subsystem
    Date
    Provides an API for offloading memory copies to DMA devices

    Signed-off-by: Chris Leech <christopher.leech@intel.com>
    ---

    drivers/Kconfig | 2
    drivers/Makefile | 1
    drivers/dma/Kconfig | 13 ++
    drivers/dma/Makefile | 1
    drivers/dma/dmaengine.c | 361 +++++++++++++++++++++++++++++++++++++++++++++
    include/linux/dmaengine.h | 322 ++++++++++++++++++++++++++++++++++++++++
    6 files changed, 700 insertions(+), 0 deletions(-)

    diff --git a/drivers/Kconfig b/drivers/Kconfig
    index bddf431..ce7ffa7 100644
    --- a/drivers/Kconfig
    +++ b/drivers/Kconfig
    @@ -70,4 +70,6 @@ source "drivers/sn/Kconfig"

    source "drivers/edac/Kconfig"

    +source "drivers/dma/Kconfig"
    +
    endmenu
    diff --git a/drivers/Makefile b/drivers/Makefile
    index 5c69b86..516ba5e 100644
    --- a/drivers/Makefile
    +++ b/drivers/Makefile
    @@ -73,3 +73,4 @@ obj-$(CONFIG_SGI_SN) += sn/
    obj-y += firmware/
    obj-$(CONFIG_CRYPTO) += crypto/
    obj-$(CONFIG_SUPERH) += sh/
    +obj-$(CONFIG_DMA_ENGINE) += dma/
    diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
    new file mode 100644
    index 0000000..f9ac4bc
    --- /dev/null
    +++ b/drivers/dma/Kconfig
    @@ -0,0 +1,13 @@
    +#
    +# 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
    diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
    new file mode 100644
    index 0000000..10b7391
    --- /dev/null
    +++ b/drivers/dma/Makefile
    @@ -0,0 +1 @@
    +obj-y += dmaengine.o
    diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
    new file mode 100644
    index 0000000..77cfcb3
    --- /dev/null
    +++ b/drivers/dma/dmaengine.c
    @@ -0,0 +1,361 @@
    +/*****************************************************************************
    +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 LICENSE.
    +*****************************************************************************/
    +#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>
    +
    +static spinlock_t dma_list_lock;
    +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;
    +
    + sprintf(buf, "%lu\n", count);
    + return strlen(buf) + 1;
    +}
    +
    +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;
    +
    + sprintf(buf, "%lu\n", count);
    + return strlen(buf) + 1;
    +}
    +
    +static ssize_t show_in_use(struct class_device *cd, char *buf)
    +{
    + struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
    +
    + sprintf(buf, "%d\n", (chan->client ? 1 : 0));
    + return strlen(buf) + 1;
    +}
    +
    +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_lock held.
    + */
    +static struct dma_chan * dma_client_chan_alloc(struct dma_client *client)
    +{
    + struct dma_device *device;
    + struct dma_chan *chan;
    + unsigned long flags;
    +
    + /* 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;
    +
    + if (chan->device->device_alloc_chan_resources(chan) >= 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_async_device_cleanup(struct kref *kref);
    +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;
    +
    + spin_lock(&dma_list_lock);
    + 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);
    + }
    + }
    + spin_unlock(&dma_list_lock);
    +}
    +
    +/**
    + * 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;
    +
    + spin_lock(&dma_list_lock);
    + list_add_tail(&client->global_node, &dma_client_list);
    + spin_unlock(&dma_list_lock);
    +
    + 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();
    +
    + spin_lock(&dma_list_lock);
    + list_del(&client->global_node);
    + spin_unlock(&dma_list_lock);
    +
    + 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);
    + }
    +
    + spin_lock(&dma_list_lock);
    + list_add_tail(&device->global_node, &dma_device_list);
    + spin_unlock(&dma_list_lock);
    +
    + 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 = 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;
    +
    + spin_lock(&dma_list_lock);
    + list_del(&device->global_node);
    + spin_unlock(&dma_list_lock);
    +
    + 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)
    +{
    + spin_lock_init(&dma_list_lock);
    +
    + 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);
    diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
    new file mode 100644
    index 0000000..f8a77ab
    --- /dev/null
    +++ b/include/linux/dmaengine.h
    @@ -0,0 +1,322 @@
    +/*****************************************************************************
    +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 LICENSE.
    +*****************************************************************************/
    +#ifndef DMAENGINE_H
    +#define DMAENGINE_H
    +
    +#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
    +{
    + 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:
    + * @client_node: used to add this to the client chan list
    + * @device_node: used to add this to the device chan list
    + */
    +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
    + * @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,
    + void *dest, void *src, size_t len)
    +{
    + int cpu = get_cpu();
    + per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
    + per_cpu_ptr(chan->local, cpu)->memcpy_count++;
    + put_cpu();
    +
    + return chan->device->device_memcpy_buf_to_buf(chan, dest, src, len);
    +}
    +
    +/**
    + * dma_async_memcpy_buf_to_pg - offloaded copy
    + * @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)
    + */
    +static inline dma_cookie_t dma_async_memcpy_buf_to_pg(struct dma_chan *chan,
    + struct page *page, unsigned int offset, void *kdata, size_t len)
    +{
    + int cpu = get_cpu();
    + per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
    + per_cpu_ptr(chan->local, cpu)->memcpy_count++;
    + put_cpu();
    +
    + return chan->device->device_memcpy_buf_to_pg(chan, page, offset,
    + kdata, len);
    +}
    +
    +/**
    + * dma_async_memcpy_buf_to_pg - offloaded copy
    + * @chan: DMA channel to offload copy to
    + * @dest_page: destination page
    + * @dest_off: offset in page to copy to
    + * @src_page: 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)
    + */
    +static inline 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)
    +{
    + int cpu = get_cpu();
    + per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
    + per_cpu_ptr(chan->local, cpu)->memcpy_count++;
    + put_cpu();
    +
    + return chan->device->device_memcpy_pg_to_pg(chan, dest_pg, dest_off,
    + src_pg, src_off, len);
    +}
    +
    +/**
    + * dma_async_memcpy_issue_pending - flush pending copies to HW
    + * @chan:
    + *
    + * This allows drivers to push copies to HW in batches,
    + * reducing MMIO writes where possible.
    + */
    +static inline void dma_async_memcpy_issue_pending(struct dma_chan *chan)
    +{
    + return chan->device->device_memcpy_issue_pending(chan);
    +}
    +
    +/**
    + * dma_async_memcpy_complete - poll for transaction completion
    + * @chan: DMA channel
    + * @cookie: transaction identifier to check status of
    + * @last: returns last completed cookie, can be NULL
    + * @used: returns last issued cookie, can be NULL
    + *
    + * If @last and @used are passed in, upon return they reflect the driver
    + * internal state and can be used with dma_async_is_complete() to check
    + * the status of multiple cookies without re-checking hardware state.
    + */
    +static inline enum dma_status dma_async_memcpy_complete(struct dma_chan *chan,
    + dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)
    +{
    + return chan->device->device_memcpy_complete(chan, cookie, last, used);
    +}
    +
    +/**
    + * dma_async_is_complete - test a cookie against chan state
    + * @cookie: transaction identifier to test status of
    + * @last_complete: last know completed transaction
    + * @last_used: last cookie value handed out
    + *
    + * dma_async_is_complete() is used in dma_async_memcpy_complete()
    + * the test logic is seperated for lightweight testing of multiple cookies
    + */
    +static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
    + dma_cookie_t last_complete, dma_cookie_t last_used) {
    + if (last_complete <= last_used) {
    + if ((cookie <= last_complete) || (cookie > last_used))
    + return DMA_SUCCESS;
    + } else {
    + if ((cookie <= last_complete) && (cookie > last_used))
    + return DMA_SUCCESS;
    + }
    + return DMA_IN_PROGRESS;
    +}
    +
    +
    +/* --- DMA device --- */
    +
    +int dma_async_device_register(struct dma_device *device);
    +void dma_async_device_unregister(struct dma_device *device);
    +
    +#endif /* DMAENGINE_H */
    -
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