/* * 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 device registered. When the * device is released, the corresponding 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 corresponding kref_put * happens. The device's release function does a completion, so * unregister_device does a remove event, 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 unregistered. 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 #include #include #include #include #include #include #include #include #include #include #include static DEFINE_MUTEX(dma_list_mutex); static LIST_HEAD(dma_device_list); static LIST_HEAD(dma_client_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 void dma_async_device_cleanup(struct kref *kref); static void dma_dev_release(struct device *dev) { struct dma_chan *chan = to_dma_chan(dev); kref_put(&chan->device->refcount, dma_async_device_cleanup); } static struct class dma_devclass = { .name = "dma", .dev_attrs = dma_attrs, .dev_release = dma_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); } 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, NULL); if (desc_cnt < 0) { err = desc_cnt; chan->client_count = 0; module_put(owner); } else 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); } /** * 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; enum dma_state_client ack; /* Find a channel */ list_for_each_entry(device, &dma_device_list, global_node) { /* Does the client require a specific DMA controller? */ if (client->slave && client->slave->dma_dev && client->slave->dma_dev != device->dev) continue; list_for_each_entry(chan, &device->channels, device_node) { if (!dma_chan_satisfies_mask(chan, client->cap_mask)) continue; if (!chan->client_count) continue; ack = client->event_callback(client, chan, DMA_RESOURCE_AVAILABLE); /* we are done once this client rejects * an available resource */ 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); 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); kref_put(&chan->refcount, dma_chan_cleanup); } static void dma_chan_release(struct dma_chan *chan) { call_rcu(&chan->rcu, dma_chan_free_rcu); } /** * 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' 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_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) 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)) 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) 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; } } /** * 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_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) { struct dma_device *device, *_d; struct dma_chan *chan; int err; /* validate client data */ BUG_ON(dma_has_cap(DMA_SLAVE, client->cap_mask) && !client->slave); mutex_lock(&dma_list_mutex); dmaengine_ref_count++; /* try to grab channels */ list_for_each_entry_safe(device, _d, &dma_device_list, global_node) 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(); 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; if (!client) return; 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) list_for_each_entry(chan, &device->channels, device_node) 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_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); init_completion(&device->done); kref_init(&device->refcount); 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) { 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->client_count = 0; chan->slow_ref = 0; INIT_RCU_HEAD(&chan->rcu); } mutex_lock(&dma_list_mutex); if (dmaengine_ref_count) 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); 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); device_unregister(&chan->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 - unregister a DMA device * @device: &dma_device */ 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); 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 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);