[I/OAT]: DMA memcpy subsystem (c13c8260) · Commits · e / devices / android_kernel_sony_msm8998

drivers/Kconfig

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		@@ -72,4 +72,6 @@ source "drivers/edac/Kconfig"

		source "drivers/rtc/Kconfig"

		source "drivers/dma/Kconfig"

		endmenu

drivers/Makefile

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		@@ -74,3 +74,4 @@ obj-$(CONFIG_SGI_SN) += sn/
		obj-y += firmware/
		obj-$(CONFIG_CRYPTO) += crypto/
		obj-$(CONFIG_SUPERH) += sh/
		obj-$(CONFIG_DMA_ENGINE) += dma/

drivers/dma/Kconfig

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		#
		# 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

drivers/dma/Makefile

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		obj-y += dmaengine.o

drivers/dma/dmaengine.c

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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 has a channels list, it's only modified under the client->lock
		* and in an RCU callback, so it's safe to read under rcu_read_lock().
		*
		* Each device has a kref, which is initialized to 1 when the device is
		* registered. A kref_put 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 single reference is set when on an
		* ADDED event, and removed with a REMOVE event. Net DMA client takes an
		* extra reference per outstanding transaction. The relase function does a
		* kref_put on the device. -ChrisL
		*/

		#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>
		#include <linux/mutex.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_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_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);

		return sprintf(buf, "%d\n", (chan->client ? 1 : 0));
		}

		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_mutex held.
		*/
		static struct dma_chan dma_client_chan_alloc(struct dma_client client)
		{
		struct dma_device *device;
		struct dma_chan *chan;
		unsigned long flags;
		int desc; /* allocated descriptor count */

		/* 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;

		desc = chan->device->device_alloc_chan_resources(chan);
		if (desc >= 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_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;

		mutex_lock(&dma_list_mutex);

		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);
		}
		}

		mutex_unlock(&dma_list_mutex);
		}

		/**
		* 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;

		mutex_lock(&dma_list_mutex);
		list_add_tail(&client->global_node, &dma_client_list);
		mutex_unlock(&dma_list_mutex);

		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();

		mutex_lock(&dma_list_mutex);
		list_del(&client->global_node);
		mutex_unlock(&dma_list_mutex);

		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);
		}

		mutex_lock(&dma_list_mutex);
		list_add_tail(&device->global_node, &dma_device_list);
		mutex_unlock(&dma_list_mutex);

		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;

		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;

		mutex_lock(&dma_list_mutex);
		list_del(&device->global_node);
		mutex_unlock(&dma_list_mutex);

		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)
		{
		mutex_init(&dma_list_mutex);
		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);
		EXPORT_SYMBOL(dma_chan_cleanup);