/* .cap_mask == 0 defaults to all channels */
};
-/**
- * dma_cap_mask_all - enable iteration over all operation types
- */
-static dma_cap_mask_t dma_cap_mask_all;
-
-/**
- * chan_ref_percpu - tracks channel allocations per core/opertion
- */
-struct chan_ref_percpu {
- struct dma_chan_ref *ref;
-};
-
-static int channel_table_initialized;
-static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END];
-
/**
* async_tx_lock - protect modification of async_tx_master_list and serialize
* rebalance operations
*/
-static spinlock_t async_tx_lock;
+static DEFINE_SPINLOCK(async_tx_lock);
static LIST_HEAD(async_tx_master_list);
atomic_set(&ref->count, 0);
}
-/**
- * get_chan_ref_by_cap - returns the nth channel of the given capability
- * defaults to returning the channel with the desired capability and the
- * lowest reference count if the index can not be satisfied
- * @cap: capability to match
- * @index: nth channel desired, passing -1 has the effect of forcing the
- * default return value
- */
-static struct dma_chan_ref *
-get_chan_ref_by_cap(enum dma_transaction_type cap, int index)
-{
- struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref;
-
- rcu_read_lock();
- list_for_each_entry_rcu(ref, &async_tx_master_list, node)
- if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
- if (!min_ref)
- min_ref = ref;
- else if (atomic_read(&ref->count) <
- atomic_read(&min_ref->count))
- min_ref = ref;
-
- if (index-- == 0) {
- ret_ref = ref;
- break;
- }
- }
- rcu_read_unlock();
-
- if (!ret_ref)
- ret_ref = min_ref;
-
- if (ret_ref)
- atomic_inc(&ret_ref->count);
-
- return ret_ref;
-}
-
-/**
- * async_tx_rebalance - redistribute the available channels, optimize
- * for cpu isolation in the SMP case, and opertaion isolation in the
- * uniprocessor case
- */
-static void async_tx_rebalance(void)
-{
- int cpu, cap, cpu_idx = 0;
- unsigned long flags;
-
- if (!channel_table_initialized)
- return;
-
- spin_lock_irqsave(&async_tx_lock, flags);
-
- /* undo the last distribution */
- for_each_dma_cap_mask(cap, dma_cap_mask_all)
- for_each_possible_cpu(cpu) {
- struct dma_chan_ref *ref =
- per_cpu_ptr(channel_table[cap], cpu)->ref;
- if (ref) {
- atomic_set(&ref->count, 0);
- per_cpu_ptr(channel_table[cap], cpu)->ref =
- NULL;
- }
- }
-
- for_each_dma_cap_mask(cap, dma_cap_mask_all)
- for_each_online_cpu(cpu) {
- struct dma_chan_ref *new;
- if (NR_CPUS > 1)
- new = get_chan_ref_by_cap(cap, cpu_idx++);
- else
- new = get_chan_ref_by_cap(cap, -1);
-
- per_cpu_ptr(channel_table[cap], cpu)->ref = new;
- }
-
- spin_unlock_irqrestore(&async_tx_lock, flags);
-}
-
static enum dma_state_client
dma_channel_add_remove(struct dma_client *client,
struct dma_chan *chan, enum dma_state state)
" (-ENOMEM)\n");
return 0;
}
-
- async_tx_rebalance();
break;
case DMA_RESOURCE_REMOVED:
found = 0;
ack = DMA_ACK;
else
break;
-
- async_tx_rebalance();
break;
case DMA_RESOURCE_SUSPEND:
case DMA_RESOURCE_RESUME:
return ack;
}
-static int __init
-async_tx_init(void)
+static int __init async_tx_init(void)
{
- enum dma_transaction_type cap;
-
- spin_lock_init(&async_tx_lock);
- bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
-
- /* an interrupt will never be an explicit operation type.
- * clearing this bit prevents allocation to a slot in 'channel_table'
- */
- clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
-
- for_each_dma_cap_mask(cap, dma_cap_mask_all) {
- channel_table[cap] = alloc_percpu(struct chan_ref_percpu);
- if (!channel_table[cap])
- goto err;
- }
-
- channel_table_initialized = 1;
dma_async_client_register(&async_tx_dma);
dma_async_client_chan_request(&async_tx_dma);
printk(KERN_INFO "async_tx: api initialized (async)\n");
return 0;
-err:
- printk(KERN_ERR "async_tx: initialization failure\n");
-
- while (--cap >= 0)
- free_percpu(channel_table[cap]);
-
- return 1;
}
static void __exit async_tx_exit(void)
{
- enum dma_transaction_type cap;
-
- channel_table_initialized = 0;
-
- for_each_dma_cap_mask(cap, dma_cap_mask_all)
- if (channel_table[cap])
- free_percpu(channel_table[cap]);
-
dma_async_client_unregister(&async_tx_dma);
}
{
/* see if we can keep the chain on one channel */
if (depend_tx &&
- dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
+ dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
return depend_tx->chan;
- else if (likely(channel_table_initialized)) {
- struct dma_chan_ref *ref;
- int cpu = get_cpu();
- ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref;
- put_cpu();
- return ref ? ref->chan : NULL;
- } else
- return NULL;
+ return dma_find_channel(tx_type);
}
EXPORT_SYMBOL_GPL(__async_tx_find_channel);
#else
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);
+
+/**
+ * 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
*/
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);
}
}
}
list_add_tail(&device->global_node, &dma_device_list);
+ dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
dma_clients_notify_available();
mutex_lock(&dma_list_mutex);
list_del(&device->global_node);
+ dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
list_for_each_entry(chan, &device->channels, device_node) {
}
subsys_initcall(dma_bus_init);
+
* @device_node: used to add this to the device chan list
* @local: per-cpu pointer to a struct dma_chan_percpu
* @client-count: how many clients are using this channel
+ * @table_count: number of appearances in the mem-to-mem allocation table
*/
struct dma_chan {
struct dma_device *device;
struct list_head device_node;
struct dma_chan_percpu *local;
int client_count;
+ int table_count;
};
#define to_dma_chan(p) container_of(p, struct dma_chan, dev)
int dma_async_device_register(struct dma_device *device);
void dma_async_device_unregister(struct dma_device *device);
void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
+struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
/* --- Helper iov-locking functions --- */
git.openpandora.org / pandora-kernel.git / commitdiff