/* * 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 a global list of dma_device structs it is protected by a * mutex, dma_list_mutex. * * A subsystem can get access to a channel by calling dmaengine_get() followed * by dma_find_channel(), or if it has need for an exclusive channel it can call * dma_request_channel(). Once a channel is allocated a reference is taken * against its corresponding driver to disable removal. * * 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. * * See Documentation/dmaengine.txt for more details */ #include <linux/dma-mapping.h>#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>#include <linux/rculist.h>#include <linux/idr.h>#include <linux/slab.h> static DEFINE_MUTEX(dma_list_mutex);static DEFINE_IDR(dma_idr);static LIST_HEAD(dma_device_list);static long dmaengine_ref_count; /* --- sysfs implementation --- */ /** * dev_to_dma_chan - convert a device pointer to the its sysfs container object * @dev - device node * * Must be called under dma_list_mutex */static struct dma_chan *dev_to_dma_chan(struct device *dev){ struct dma_chan_dev *chan_dev; chan_dev = container_of(dev, typeof(*chan_dev), device); return chan_dev->chan;} static ssize_t show_memcpy_count(struct device *dev, struct device_attribute *attr, char *buf){ struct dma_chan *chan; unsigned long count = 0; int i; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) { for_each_possible_cpu(i) count += per_cpu_ptr(chan->local, i)->memcpy_count; err = sprintf(buf, "%lu\n", count); } else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err;} static ssize_t show_bytes_transferred(struct device *dev, struct device_attribute *attr, char *buf){ struct dma_chan *chan; unsigned long count = 0; int i; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) { for_each_possible_cpu(i) count += per_cpu_ptr(chan->local, i)->bytes_transferred; err = sprintf(buf, "%lu\n", count); } else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err;} static ssize_t show_in_use(struct device *dev, struct device_attribute *attr, char *buf){ struct dma_chan *chan; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) err = sprintf(buf, "%d\n", chan->client_count); else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err;} 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 chan_dev_release(struct device *dev){ struct dma_chan_dev *chan_dev; chan_dev = container_of(dev, typeof(*chan_dev), device); if (atomic_dec_and_test(chan_dev->idr_ref)) { mutex_lock(&dma_list_mutex); idr_remove(&dma_idr, chan_dev->dev_id); mutex_unlock(&dma_list_mutex); kfree(chan_dev->idr_ref); } kfree(chan_dev);} static struct class dma_devclass = { .name = "dma", .dev_attrs = dma_attrs, .dev_release = chan_dev_release,}; /* --- client and device registration --- */ #define dma_device_satisfies_mask(device, mask) \ __dma_device_satisfies_mask((device), &(mask))static int__dma_device_satisfies_mask(struct dma_device *device, dma_cap_mask_t *want){ dma_cap_mask_t has; bitmap_and(has.bits, want->bits, 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); if (desc_cnt < 0) { err = desc_cnt; chan->client_count = 0; module_put(owner); } else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask)) 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);} 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_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 __percpu *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', 'private', 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_PRIVATE, 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;}arch_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){ return this_cpu_read(channel_table[tx_type]->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; rcu_read_lock(); list_for_each_entry_rcu(device, &dma_device_list, global_node) { if (dma_has_cap(DMA_PRIVATE, device->cap_mask)) continue; 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) || dma_has_cap(DMA_PRIVATE, 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) { if (dma_has_cap(DMA_PRIVATE, device->cap_mask)) continue; 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; }} static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev, dma_filter_fn fn, void *fn_param){ struct dma_chan *chan; if (!__dma_device_satisfies_mask(dev, mask)) { pr_debug("%s: wrong capabilities\n", __func__); return NULL; } /* devices with multiple channels need special handling as we need to * ensure that all channels are either private or public. */ if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask)) list_for_each_entry(chan, &dev->channels, device_node) { /* some channels are already publicly allocated */ if (chan->client_count) return NULL; } list_for_each_entry(chan, &dev->channels, device_node) { if (chan->client_count) { pr_debug("%s: %s busy\n", __func__, dma_chan_name(chan)); continue; } if (fn && !fn(chan, fn_param)) { pr_debug("%s: %s filter said false\n", __func__, dma_chan_name(chan)); continue; } return chan; } return NULL;} /** * dma_request_channel - try to allocate an exclusive channel * @mask: capabilities that the channel must satisfy * @fn: optional callback to disposition available channels * @fn_param: opaque parameter to pass to dma_filter_fn */struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param){ struct dma_device *device, *_d; struct dma_chan *chan = NULL; int err; /* Find a channel */ mutex_lock(&dma_list_mutex); list_for_each_entry_safe(device, _d, &dma_device_list, global_node) { chan = private_candidate(mask, device, fn, fn_param); if (chan) { /* Found a suitable channel, try to grab, prep, and * return it. We first set DMA_PRIVATE to disableLines 1–500 of 1057. Load more
/* * 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 a global list of dma_device structs it is protected by a * mutex, dma_list_mutex. * * A subsystem can get access to a channel by calling dmaengine_get() followed * by dma_find_channel(), or if it has need for an exclusive channel it can call * dma_request_channel(). Once a channel is allocated a reference is taken * against its corresponding driver to disable removal. * * 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. * * See Documentation/dmaengine.txt for more details */ #include <linux/dma-mapping.h> #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> #include <linux/rculist.h> #include <linux/idr.h> #include <linux/slab.h> static DEFINE_MUTEX(dma_list_mutex); static DEFINE_IDR(dma_idr); static LIST_HEAD(dma_device_list); static long dmaengine_ref_count; /* --- sysfs implementation --- */ /** * dev_to_dma_chan - convert a device pointer to the its sysfs container object * @dev - device node * * Must be called under dma_list_mutex */ static struct dma_chan *dev_to_dma_chan(struct device *dev) { struct dma_chan_dev *chan_dev; chan_dev = container_of(dev, typeof(*chan_dev), device); return chan_dev->chan; } static ssize_t show_memcpy_count(struct device *dev, struct device_attribute *attr, char *buf) { struct dma_chan *chan; unsigned long count = 0; int i; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) { for_each_possible_cpu(i) count += per_cpu_ptr(chan->local, i)->memcpy_count; err = sprintf(buf, "%lu\n", count); } else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err; } static ssize_t show_bytes_transferred(struct device *dev, struct device_attribute *attr, char *buf) { struct dma_chan *chan; unsigned long count = 0; int i; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) { for_each_possible_cpu(i) count += per_cpu_ptr(chan->local, i)->bytes_transferred; err = sprintf(buf, "%lu\n", count); } else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err; } static ssize_t show_in_use(struct device *dev, struct device_attribute *attr, char *buf) { struct dma_chan *chan; int err; mutex_lock(&dma_list_mutex); chan = dev_to_dma_chan(dev); if (chan) err = sprintf(buf, "%d\n", chan->client_count); else err = -ENODEV; mutex_unlock(&dma_list_mutex); return err; } 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 chan_dev_release(struct device *dev) { struct dma_chan_dev *chan_dev; chan_dev = container_of(dev, typeof(*chan_dev), device); if (atomic_dec_and_test(chan_dev->idr_ref)) { mutex_lock(&dma_list_mutex); idr_remove(&dma_idr, chan_dev->dev_id); mutex_unlock(&dma_list_mutex); kfree(chan_dev->idr_ref); } kfree(chan_dev); } static struct class dma_devclass = { .name = "dma", .dev_attrs = dma_attrs, .dev_release = chan_dev_release, }; /* --- client and device registration --- */ #define dma_device_satisfies_mask(device, mask) \ __dma_device_satisfies_mask((device), &(mask)) static int __dma_device_satisfies_mask(struct dma_device *device, dma_cap_mask_t *want) { dma_cap_mask_t has; bitmap_and(has.bits, want->bits, 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); if (desc_cnt < 0) { err = desc_cnt; chan->client_count = 0; module_put(owner); } else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask)) 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); } 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_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 __percpu *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', 'private', 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_PRIVATE, 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; } arch_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) { return this_cpu_read(channel_table[tx_type]->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; rcu_read_lock(); list_for_each_entry_rcu(device, &dma_device_list, global_node) { if (dma_has_cap(DMA_PRIVATE, device->cap_mask)) continue; 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) || dma_has_cap(DMA_PRIVATE, 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) { if (dma_has_cap(DMA_PRIVATE, device->cap_mask)) continue; 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; } } static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev, dma_filter_fn fn, void *fn_param) { struct dma_chan *chan; if (!__dma_device_satisfies_mask(dev, mask)) { pr_debug("%s: wrong capabilities\n", __func__); return NULL; } /* devices with multiple channels need special handling as we need to * ensure that all channels are either private or public. */ if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask)) list_for_each_entry(chan, &dev->channels, device_node) { /* some channels are already publicly allocated */ if (chan->client_count) return NULL; } list_for_each_entry(chan, &dev->channels, device_node) { if (chan->client_count) { pr_debug("%s: %s busy\n", __func__, dma_chan_name(chan)); continue; } if (fn && !fn(chan, fn_param)) { pr_debug("%s: %s filter said false\n", __func__, dma_chan_name(chan)); continue; } return chan; } return NULL; } /** * dma_request_channel - try to allocate an exclusive channel * @mask: capabilities that the channel must satisfy * @fn: optional callback to disposition available channels * @fn_param: opaque parameter to pass to dma_filter_fn */ struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param) { struct dma_device *device, *_d; struct dma_chan *chan = NULL; int err; /* Find a channel */ mutex_lock(&dma_list_mutex); list_for_each_entry_safe(device, _d, &dma_device_list, global_node) { chan = private_candidate(mask, device, fn, fn_param); if (chan) { /* Found a suitable channel, try to grab, prep, and * return it. We first set DMA_PRIVATE to disable