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/*

 * 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);

                                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);

        }

        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);

                }

        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;

                }

                /* One for the channel, one of the class device */

                kref_get(&device->refcount);

                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);