gpu: ion: Add ION Memory Manager

Signed-off-by: Rebecca Schultz Zavin <[e-mail]>
[jstultz: Squished in Colin Cross' move to staging change,
also disables ION from the build, as it won't compile till
the end of the patchset]
Signed-off-by: John Stultz <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/android/Kconfig

···
 	  *WARNING* improper use of this can result in deadlocking kernel
 	  drivers from userspace.
 
+source "drivers/staging/android/ion/Kconfig"
+
 endif # if ANDROID
 
 endmenu

drivers/staging/android/Makefile

···
 ccflags-y += -I$(src)			# needed for trace events
 
+# ION doesn't build just yet, so disable it from the build
+#obj-y					+= ion/
+
 obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o
 obj-$(CONFIG_ASHMEM)			+= ashmem.o
 obj-$(CONFIG_ANDROID_LOGGER)		+= logger.o

drivers/staging/android/ion/Kconfig

···
+menuconfig ION
+	tristate "Ion Memory Manager"
+	select GENERIC_ALLOCATOR
+	help
+	  Chose this option to enable the ION Memory Manager.
+
+config ION_TEGRA
+	tristate "Ion for Tegra"
+	depends on ARCH_TEGRA && ION
+	help
+	  Choose this option if you wish to use ion on an nVidia Tegra.
+

drivers/staging/android/ion/Makefile

···
+obj-$(CONFIG_ION) +=	ion.o ion_heap.o ion_system_heap.o ion_carveout_heap.o
+obj-$(CONFIG_ION_TEGRA) += tegra/

drivers/staging/android/ion/ion.c

···
+/*
+ * drivers/staging/android/ion/ion.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/anon_inodes.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/rbtree.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+
+#include "ion.h"
+#include "ion_priv.h"
+#define DEBUG
+
+/**
+ * struct ion_device - the metadata of the ion device node
+ * @dev:		the actual misc device
+ * @buffers:	an rb tree of all the existing buffers
+ * @lock:		lock protecting the buffers & heaps trees
+ * @heaps:		list of all the heaps in the system
+ * @user_clients:	list of all the clients created from userspace
+ */
+struct ion_device {
+	struct miscdevice dev;
+	struct rb_root buffers;
+	struct mutex lock;
+	struct rb_root heaps;
+	long (*custom_ioctl) (struct ion_client *client, unsigned int cmd,
+			      unsigned long arg);
+	struct rb_root user_clients;
+	struct rb_root kernel_clients;
+	struct dentry *debug_root;
+};
+
+/**
+ * struct ion_client - a process/hw block local address space
+ * @ref:		for reference counting the client
+ * @node:		node in the tree of all clients
+ * @dev:		backpointer to ion device
+ * @handles:		an rb tree of all the handles in this client
+ * @lock:		lock protecting the tree of handles
+ * @heap_mask:		mask of all supported heaps
+ * @name:		used for debugging
+ * @task:		used for debugging
+ *
+ * A client represents a list of buffers this client may access.
+ * The mutex stored here is used to protect both handles tree
+ * as well as the handles themselves, and should be held while modifying either.
+ */
+struct ion_client {
+	struct kref ref;
+	struct rb_node node;
+	struct ion_device *dev;
+	struct rb_root handles;
+	struct mutex lock;
+	unsigned int heap_mask;
+	const char *name;
+	struct task_struct *task;
+	pid_t pid;
+	struct dentry *debug_root;
+};
+
+/**
+ * ion_handle - a client local reference to a buffer
+ * @ref:		reference count
+ * @client:		back pointer to the client the buffer resides in
+ * @buffer:		pointer to the buffer
+ * @node:		node in the client's handle rbtree
+ * @kmap_cnt:		count of times this client has mapped to kernel
+ * @dmap_cnt:		count of times this client has mapped for dma
+ * @usermap_cnt:	count of times this client has mapped for userspace
+ *
+ * Modifications to node, map_cnt or mapping should be protected by the
+ * lock in the client.  Other fields are never changed after initialization.
+ */
+struct ion_handle {
+	struct kref ref;
+	struct ion_client *client;
+	struct ion_buffer *buffer;
+	struct rb_node node;
+	unsigned int kmap_cnt;
+	unsigned int dmap_cnt;
+	unsigned int usermap_cnt;
+};
+
+/* this function should only be called while dev->lock is held */
+static void ion_buffer_add(struct ion_device *dev,
+			   struct ion_buffer *buffer)
+{
+	struct rb_node **p = &dev->buffers.rb_node;
+	struct rb_node *parent = NULL;
+	struct ion_buffer *entry;
+
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct ion_buffer, node);
+
+		if (buffer < entry) {
+			p = &(*p)->rb_left;
+		} else if (buffer > entry) {
+			p = &(*p)->rb_right;
+		} else {
+			pr_err("%s: buffer already found.", __func__);
+			BUG();
+		}
+	}
+
+	rb_link_node(&buffer->node, parent, p);
+	rb_insert_color(&buffer->node, &dev->buffers);
+}
+
+/* this function should only be called while dev->lock is held */
+static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
+				     struct ion_device *dev,
+				     unsigned long len,
+				     unsigned long align,
+				     unsigned long flags)
+{
+	struct ion_buffer *buffer;
+	int ret;
+
+	buffer = kzalloc(sizeof(struct ion_buffer), GFP_KERNEL);
+	if (!buffer)
+		return ERR_PTR(-ENOMEM);
+
+	buffer->heap = heap;
+	kref_init(&buffer->ref);
+
+	ret = heap->ops->allocate(heap, buffer, len, align, flags);
+	if (ret) {
+		kfree(buffer);
+		return ERR_PTR(ret);
+	}
+	buffer->dev = dev;
+	buffer->size = len;
+	mutex_init(&buffer->lock);
+	ion_buffer_add(dev, buffer);
+	return buffer;
+}
+
+static void ion_buffer_destroy(struct kref *kref)
+{
+	struct ion_buffer *buffer = container_of(kref, struct ion_buffer, ref);
+	struct ion_device *dev = buffer->dev;
+
+	buffer->heap->ops->free(buffer);
+	mutex_lock(&dev->lock);
+	rb_erase(&buffer->node, &dev->buffers);
+	mutex_unlock(&dev->lock);
+	kfree(buffer);
+}
+
+static void ion_buffer_get(struct ion_buffer *buffer)
+{
+	kref_get(&buffer->ref);
+}
+
+static int ion_buffer_put(struct ion_buffer *buffer)
+{
+	return kref_put(&buffer->ref, ion_buffer_destroy);
+}
+
+static struct ion_handle *ion_handle_create(struct ion_client *client,
+				     struct ion_buffer *buffer)
+{
+	struct ion_handle *handle;
+
+	handle = kzalloc(sizeof(struct ion_handle), GFP_KERNEL);
+	if (!handle)
+		return ERR_PTR(-ENOMEM);
+	kref_init(&handle->ref);
+	RB_CLEAR_NODE(&handle->node);
+	handle->client = client;
+	ion_buffer_get(buffer);
+	handle->buffer = buffer;
+
+	return handle;
+}
+
+static void ion_handle_destroy(struct kref *kref)
+{
+	struct ion_handle *handle = container_of(kref, struct ion_handle, ref);
+	/* XXX Can a handle be destroyed while it's map count is non-zero?:
+	   if (handle->map_cnt) unmap
+	 */
+	ion_buffer_put(handle->buffer);
+	mutex_lock(&handle->client->lock);
+	if (!RB_EMPTY_NODE(&handle->node))
+		rb_erase(&handle->node, &handle->client->handles);
+	mutex_unlock(&handle->client->lock);
+	kfree(handle);
+}
+
+struct ion_buffer *ion_handle_buffer(struct ion_handle *handle)
+{
+	return handle->buffer;
+}
+
+static void ion_handle_get(struct ion_handle *handle)
+{
+	kref_get(&handle->ref);
+}
+
+static int ion_handle_put(struct ion_handle *handle)
+{
+	return kref_put(&handle->ref, ion_handle_destroy);
+}
+
+static struct ion_handle *ion_handle_lookup(struct ion_client *client,
+					    struct ion_buffer *buffer)
+{
+	struct rb_node *n;
+
+	for (n = rb_first(&client->handles); n; n = rb_next(n)) {
+		struct ion_handle *handle = rb_entry(n, struct ion_handle,
+						     node);
+		if (handle->buffer == buffer)
+			return handle;
+	}
+	return NULL;
+}
+
+static bool ion_handle_validate(struct ion_client *client, struct ion_handle *handle)
+{
+	struct rb_node *n = client->handles.rb_node;
+
+	while (n) {
+		struct ion_handle *handle_node = rb_entry(n, struct ion_handle,
+							  node);
+		if (handle < handle_node)
+			n = n->rb_left;
+		else if (handle > handle_node)
+			n = n->rb_right;
+		else
+			return true;
+	}
+	return false;
+}
+
+static void ion_handle_add(struct ion_client *client, struct ion_handle *handle)
+{
+	struct rb_node **p = &client->handles.rb_node;
+	struct rb_node *parent = NULL;
+	struct ion_handle *entry;
+
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct ion_handle, node);
+
+		if (handle < entry)
+			p = &(*p)->rb_left;
+		else if (handle > entry)
+			p = &(*p)->rb_right;
+		else
+			WARN(1, "%s: buffer already found.", __func__);
+	}
+
+	rb_link_node(&handle->node, parent, p);
+	rb_insert_color(&handle->node, &client->handles);
+}
+
+struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
+			     size_t align, unsigned int flags)
+{
+	struct rb_node *n;
+	struct ion_handle *handle;
+	struct ion_device *dev = client->dev;
+	struct ion_buffer *buffer = NULL;
+
+	/*
+	 * traverse the list of heaps available in this system in priority
+	 * order.  If the heap type is supported by the client, and matches the
+	 * request of the caller allocate from it.  Repeat until allocate has
+	 * succeeded or all heaps have been tried
+	 */
+	mutex_lock(&dev->lock);
+	for (n = rb_first(&dev->heaps); n != NULL; n = rb_next(n)) {
+		struct ion_heap *heap = rb_entry(n, struct ion_heap, node);
+		/* if the client doesn't support this heap type */
+		if (!((1 << heap->type) & client->heap_mask))
+			continue;
+		/* if the caller didn't specify this heap type */
+		if (!((1 << heap->id) & flags))
+			continue;
+		buffer = ion_buffer_create(heap, dev, len, align, flags);
+		if (!IS_ERR_OR_NULL(buffer))
+			break;
+	}
+	mutex_unlock(&dev->lock);
+
+	if (IS_ERR_OR_NULL(buffer))
+		return ERR_PTR(PTR_ERR(buffer));
+
+	handle = ion_handle_create(client, buffer);
+
+	if (IS_ERR_OR_NULL(handle))
+		goto end;
+
+	/*
+	 * ion_buffer_create will create a buffer with a ref_cnt of 1,
+	 * and ion_handle_create will take a second reference, drop one here
+	 */
+	ion_buffer_put(buffer);
+
+	mutex_lock(&client->lock);
+	ion_handle_add(client, handle);
+	mutex_unlock(&client->lock);
+	return handle;
+
+end:
+	ion_buffer_put(buffer);
+	return handle;
+}
+
+void ion_free(struct ion_client *client, struct ion_handle *handle)
+{
+	bool valid_handle;
+
+	BUG_ON(client != handle->client);
+
+	mutex_lock(&client->lock);
+	valid_handle = ion_handle_validate(client, handle);
+	mutex_unlock(&client->lock);
+
+	if (!valid_handle) {
+		WARN("%s: invalid handle passed to free.\n", __func__);
+		return;
+	}
+	ion_handle_put(handle);
+}
+
+static void ion_client_get(struct ion_client *client);
+static int ion_client_put(struct ion_client *client);
+
+static bool _ion_map(int *buffer_cnt, int *handle_cnt)
+{
+	bool map;
+
+	BUG_ON(*handle_cnt != 0 && *buffer_cnt == 0);
+
+	if (*buffer_cnt)
+		map = false;
+	else
+		map = true;
+	if (*handle_cnt == 0)
+		(*buffer_cnt)++;
+	(*handle_cnt)++;
+	return map;
+}
+
+static bool _ion_unmap(int *buffer_cnt, int *handle_cnt)
+{
+	BUG_ON(*handle_cnt == 0);
+	(*handle_cnt)--;
+	if (*handle_cnt != 0)
+		return false;
+	BUG_ON(*buffer_cnt == 0);
+	(*buffer_cnt)--;
+	if (*buffer_cnt == 0)
+		return true;
+	return false;
+}
+
+int ion_phys(struct ion_client *client, struct ion_handle *handle,
+	     ion_phys_addr_t *addr, size_t *len)
+{
+	struct ion_buffer *buffer;
+	int ret;
+
+	mutex_lock(&client->lock);
+	if (!ion_handle_validate(client, handle)) {
+		mutex_unlock(&client->lock);
+		return -EINVAL;
+	}
+
+	buffer = handle->buffer;
+
+	if (!buffer->heap->ops->phys) {
+		pr_err("%s: ion_phys is not implemented by this heap.\n",
+		       __func__);
+		mutex_unlock(&client->lock);
+		return -ENODEV;
+	}
+	mutex_unlock(&client->lock);
+	ret = buffer->heap->ops->phys(buffer->heap, buffer, addr, len);
+	return ret;
+}
+
+void *ion_map_kernel(struct ion_client *client, struct ion_handle *handle)
+{
+	struct ion_buffer *buffer;
+	void *vaddr;
+
+	mutex_lock(&client->lock);
+	if (!ion_handle_validate(client, handle)) {
+		pr_err("%s: invalid handle passed to map_kernel.\n",
+		       __func__);
+		mutex_unlock(&client->lock);
+		return ERR_PTR(-EINVAL);
+	}
+
+	buffer = handle->buffer;
+	mutex_lock(&buffer->lock);
+
+	if (!handle->buffer->heap->ops->map_kernel) {
+		pr_err("%s: map_kernel is not implemented by this heap.\n",
+		       __func__);
+		mutex_unlock(&buffer->lock);
+		mutex_unlock(&client->lock);
+		return ERR_PTR(-ENODEV);
+	}
+
+	if (_ion_map(&buffer->kmap_cnt, &handle->kmap_cnt)) {
+		vaddr = buffer->heap->ops->map_kernel(buffer->heap, buffer);
+		if (IS_ERR_OR_NULL(vaddr))
+			_ion_unmap(&buffer->kmap_cnt, &handle->kmap_cnt);
+		buffer->vaddr = vaddr;
+	} else {
+		vaddr = buffer->vaddr;
+	}
+	mutex_unlock(&buffer->lock);
+	mutex_unlock(&client->lock);
+	return vaddr;
+}
+
+struct scatterlist *ion_map_dma(struct ion_client *client,
+				struct ion_handle *handle)
+{
+	struct ion_buffer *buffer;
+	struct scatterlist *sglist;
+
+	mutex_lock(&client->lock);
+	if (!ion_handle_validate(client, handle)) {
+		pr_err("%s: invalid handle passed to map_dma.\n",
+		       __func__);
+		mutex_unlock(&client->lock);
+		return ERR_PTR(-EINVAL);
+	}
+	buffer = handle->buffer;
+	mutex_lock(&buffer->lock);
+
+	if (!handle->buffer->heap->ops->map_dma) {
+		pr_err("%s: map_kernel is not implemented by this heap.\n",
+		       __func__);
+		mutex_unlock(&buffer->lock);
+		mutex_unlock(&client->lock);
+		return ERR_PTR(-ENODEV);
+	}
+	if (_ion_map(&buffer->dmap_cnt, &handle->dmap_cnt)) {
+		sglist = buffer->heap->ops->map_dma(buffer->heap, buffer);
+		if (IS_ERR_OR_NULL(sglist))
+			_ion_unmap(&buffer->dmap_cnt, &handle->dmap_cnt);
+		buffer->sglist = sglist;
+	} else {
+		sglist = buffer->sglist;
+	}
+	mutex_unlock(&buffer->lock);
+	mutex_unlock(&client->lock);
+	return sglist;
+}
+
+void ion_unmap_kernel(struct ion_client *client, struct ion_handle *handle)
+{
+	struct ion_buffer *buffer;
+
+	mutex_lock(&client->lock);
+	buffer = handle->buffer;
+	mutex_lock(&buffer->lock);
+	if (_ion_unmap(&buffer->kmap_cnt, &handle->kmap_cnt)) {
+		buffer->heap->ops->unmap_kernel(buffer->heap, buffer);
+		buffer->vaddr = NULL;
+	}
+	mutex_unlock(&buffer->lock);
+	mutex_unlock(&client->lock);
+}
+
+void ion_unmap_dma(struct ion_client *client, struct ion_handle *handle)
+{
+	struct ion_buffer *buffer;
+
+	mutex_lock(&client->lock);
+	buffer = handle->buffer;
+	mutex_lock(&buffer->lock);
+	if (_ion_unmap(&buffer->dmap_cnt, &handle->dmap_cnt)) {
+		buffer->heap->ops->unmap_dma(buffer->heap, buffer);
+		buffer->sglist = NULL;
+	}
+	mutex_unlock(&buffer->lock);
+	mutex_unlock(&client->lock);
+}
+
+
+struct ion_buffer *ion_share(struct ion_client *client,
+				 struct ion_handle *handle)
+{
+	bool valid_handle;
+
+	mutex_lock(&client->lock);
+	valid_handle = ion_handle_validate(client, handle);
+	mutex_unlock(&client->lock);
+	if (!valid_handle) {
+		WARN("%s: invalid handle passed to share.\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* do not take an extra reference here, the burden is on the caller
+	 * to make sure the buffer doesn't go away while it's passing it
+	 * to another client -- ion_free should not be called on this handle
+	 * until the buffer has been imported into the other client
+	 */
+	return handle->buffer;
+}
+
+struct ion_handle *ion_import(struct ion_client *client,
+			      struct ion_buffer *buffer)
+{
+	struct ion_handle *handle = NULL;
+
+	mutex_lock(&client->lock);
+	/* if a handle exists for this buffer just take a reference to it */
+	handle = ion_handle_lookup(client, buffer);
+	if (!IS_ERR_OR_NULL(handle)) {
+		ion_handle_get(handle);
+		goto end;
+	}
+	handle = ion_handle_create(client, buffer);
+	if (IS_ERR_OR_NULL(handle))
+		goto end;
+	ion_handle_add(client, handle);
+end:
+	mutex_unlock(&client->lock);
+	return handle;
+}
+
+static const struct file_operations ion_share_fops;
+
+struct ion_handle *ion_import_fd(struct ion_client *client, int fd)
+{
+	struct file *file = fget(fd);
+	struct ion_handle *handle;
+
+	if (!file) {
+		pr_err("%s: imported fd not found in file table.\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	if (file->f_op != &ion_share_fops) {
+		pr_err("%s: imported file is not a shared ion file.\n",
+		       __func__);
+		handle = ERR_PTR(-EINVAL);
+		goto end;
+	}
+	handle = ion_import(client, file->private_data);
+end:
+	fput(file);
+	return handle;
+}
+
+static int ion_debug_client_show(struct seq_file *s, void *unused)
+{
+	struct ion_client *client = s->private;
+	struct rb_node *n;
+	size_t sizes[ION_NUM_HEAPS] = {0};
+	const char *names[ION_NUM_HEAPS] = {0};
+	int i;
+
+	mutex_lock(&client->lock);
+	for (n = rb_first(&client->handles); n; n = rb_next(n)) {
+		struct ion_handle *handle = rb_entry(n, struct ion_handle,
+						     node);
+		enum ion_heap_type type = handle->buffer->heap->type;
+
+		if (!names[type])
+			names[type] = handle->buffer->heap->name;
+		sizes[type] += handle->buffer->size;
+	}
+	mutex_unlock(&client->lock);
+
+	seq_printf(s, "%16.16s: %16.16s\n", "heap_name", "size_in_bytes");
+	for (i = 0; i < ION_NUM_HEAPS; i++) {
+		if (!names[i])
+			continue;
+		seq_printf(s, "%16.16s: %16u %d\n", names[i], sizes[i],
+			   atomic_read(&client->ref.refcount));
+	}
+	return 0;
+}
+
+static int ion_debug_client_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, ion_debug_client_show, inode->i_private);
+}
+
+static const struct file_operations debug_client_fops = {
+	.open = ion_debug_client_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static struct ion_client *ion_client_lookup(struct ion_device *dev,
+					    struct task_struct *task)
+{
+	struct rb_node *n = dev->user_clients.rb_node;
+	struct ion_client *client;
+
+	mutex_lock(&dev->lock);
+	while (n) {
+		client = rb_entry(n, struct ion_client, node);
+		if (task == client->task) {
+			ion_client_get(client);
+			mutex_unlock(&dev->lock);
+			return client;
+		} else if (task < client->task) {
+			n = n->rb_left;
+		} else if (task > client->task) {
+			n = n->rb_right;
+		}
+	}
+	mutex_unlock(&dev->lock);
+	return NULL;
+}
+
+struct ion_client *ion_client_create(struct ion_device *dev,
+				     unsigned int heap_mask,
+				     const char *name)
+{
+	struct ion_client *client;
+	struct task_struct *task;
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+	struct ion_client *entry;
+	char debug_name[64];
+	pid_t pid;
+
+	get_task_struct(current->group_leader);
+	task_lock(current->group_leader);
+	pid = task_pid_nr(current->group_leader);
+	/* don't bother to store task struct for kernel threads,
+	   they can't be killed anyway */
+	if (current->group_leader->flags & PF_KTHREAD) {
+		put_task_struct(current->group_leader);
+		task = NULL;
+	} else {
+		task = current->group_leader;
+	}
+	task_unlock(current->group_leader);
+
+	/* if this isn't a kernel thread, see if a client already
+	   exists */
+	if (task) {
+		client = ion_client_lookup(dev, task);
+		if (!IS_ERR_OR_NULL(client)) {
+			put_task_struct(current->group_leader);
+			return client;
+		}
+	}
+
+	client = kzalloc(sizeof(struct ion_client), GFP_KERNEL);
+	if (!client) {
+		put_task_struct(current->group_leader);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	client->dev = dev;
+	client->handles = RB_ROOT;
+	mutex_init(&client->lock);
+	client->name = name;
+	client->heap_mask = heap_mask;
+	client->task = task;
+	client->pid = pid;
+	kref_init(&client->ref);
+
+	mutex_lock(&dev->lock);
+	if (task) {
+		p = &dev->user_clients.rb_node;
+		while (*p) {
+			parent = *p;
+			entry = rb_entry(parent, struct ion_client, node);
+
+			if (task < entry->task)
+				p = &(*p)->rb_left;
+			else if (task > entry->task)
+				p = &(*p)->rb_right;
+		}
+		rb_link_node(&client->node, parent, p);
+		rb_insert_color(&client->node, &dev->user_clients);
+	} else {
+		p = &dev->kernel_clients.rb_node;
+		while (*p) {
+			parent = *p;
+			entry = rb_entry(parent, struct ion_client, node);
+
+			if (client < entry)
+				p = &(*p)->rb_left;
+			else if (client > entry)
+				p = &(*p)->rb_right;
+		}
+		rb_link_node(&client->node, parent, p);
+		rb_insert_color(&client->node, &dev->kernel_clients);
+	}
+
+	snprintf(debug_name, 64, "%u", client->pid);
+	client->debug_root = debugfs_create_file(debug_name, 0664,
+						 dev->debug_root, client,
+						 &debug_client_fops);
+	mutex_unlock(&dev->lock);
+
+	return client;
+}
+
+static void _ion_client_destroy(struct kref *kref)
+{
+	struct ion_client *client = container_of(kref, struct ion_client, ref);
+	struct ion_device *dev = client->dev;
+	struct rb_node *n;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	while ((n = rb_first(&client->handles))) {
+		struct ion_handle *handle = rb_entry(n, struct ion_handle,
+						     node);
+		ion_handle_destroy(&handle->ref);
+	}
+	mutex_lock(&dev->lock);
+	if (client->task) {
+		rb_erase(&client->node, &dev->user_clients);
+		put_task_struct(client->task);
+	} else {
+		rb_erase(&client->node, &dev->kernel_clients);
+	}
+	debugfs_remove_recursive(client->debug_root);
+	mutex_unlock(&dev->lock);
+
+	kfree(client);
+}
+
+static void ion_client_get(struct ion_client *client)
+{
+	kref_get(&client->ref);
+}
+
+static int ion_client_put(struct ion_client *client)
+{
+	return kref_put(&client->ref, _ion_client_destroy);
+}
+
+void ion_client_destroy(struct ion_client *client)
+{
+	ion_client_put(client);
+}
+
+static int ion_share_release(struct inode *inode, struct file* file)
+{
+	struct ion_buffer *buffer = file->private_data;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	/* drop the reference to the buffer -- this prevents the
+	   buffer from going away because the client holding it exited
+	   while it was being passed */
+	ion_buffer_put(buffer);
+	return 0;
+}
+
+static void ion_vma_open(struct vm_area_struct *vma)
+{
+
+	struct ion_buffer *buffer = vma->vm_file->private_data;
+	struct ion_handle *handle = vma->vm_private_data;
+	struct ion_client *client;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	/* check that the client still exists and take a reference so
+	   it can't go away until this vma is closed */
+	client = ion_client_lookup(buffer->dev, current->group_leader);
+	if (IS_ERR_OR_NULL(client)) {
+		vma->vm_private_data = NULL;
+		return;
+	}
+	pr_debug("%s: %d client_cnt %d handle_cnt %d alloc_cnt %d\n",
+		 __func__, __LINE__,
+		 atomic_read(&client->ref.refcount),
+		 atomic_read(&handle->ref.refcount),
+		 atomic_read(&buffer->ref.refcount));
+}
+
+static void ion_vma_close(struct vm_area_struct *vma)
+{
+	struct ion_handle *handle = vma->vm_private_data;
+	struct ion_buffer *buffer = vma->vm_file->private_data;
+	struct ion_client *client;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	/* this indicates the client is gone, nothing to do here */
+	if (!handle)
+		return;
+	client = handle->client;
+	pr_debug("%s: %d client_cnt %d handle_cnt %d alloc_cnt %d\n",
+		 __func__, __LINE__,
+		 atomic_read(&client->ref.refcount),
+		 atomic_read(&handle->ref.refcount),
+		 atomic_read(&buffer->ref.refcount));
+	ion_handle_put(handle);
+	ion_client_put(client);
+	pr_debug("%s: %d client_cnt %d handle_cnt %d alloc_cnt %d\n",
+		 __func__, __LINE__,
+		 atomic_read(&client->ref.refcount),
+		 atomic_read(&handle->ref.refcount),
+		 atomic_read(&buffer->ref.refcount));
+}
+
+static struct vm_operations_struct ion_vm_ops = {
+	.open = ion_vma_open,
+	.close = ion_vma_close,
+};
+
+static int ion_share_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct ion_buffer *buffer = file->private_data;
+	unsigned long size = vma->vm_end - vma->vm_start;
+	struct ion_client *client;
+	struct ion_handle *handle;
+	int ret;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	/* make sure the client still exists, it's possible for the client to
+	   have gone away but the map/share fd still to be around, take
+	   a reference to it so it can't go away while this mapping exists */
+	client = ion_client_lookup(buffer->dev, current->group_leader);
+	if (IS_ERR_OR_NULL(client)) {
+		pr_err("%s: trying to mmap an ion handle in a process with no "
+		       "ion client\n", __func__);
+		return -EINVAL;
+	}
+
+	if ((size > buffer->size) || (size + (vma->vm_pgoff << PAGE_SHIFT) >
+				     buffer->size)) {
+		pr_err("%s: trying to map larger area than handle has available"
+		       "\n", __func__);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	/* find the handle and take a reference to it */
+	handle = ion_import(client, buffer);
+	if (IS_ERR_OR_NULL(handle)) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (!handle->buffer->heap->ops->map_user) {
+		pr_err("%s: this heap does not define a method for mapping "
+		       "to userspace\n", __func__);
+		ret = -EINVAL;
+		goto err1;
+	}
+
+	mutex_lock(&buffer->lock);
+	/* now map it to userspace */
+	ret = buffer->heap->ops->map_user(buffer->heap, buffer, vma);
+	mutex_unlock(&buffer->lock);
+	if (ret) {
+		pr_err("%s: failure mapping buffer to userspace\n",
+		       __func__);
+		goto err1;
+	}
+
+	vma->vm_ops = &ion_vm_ops;
+	/* move the handle into the vm_private_data so we can access it from
+	   vma_open/close */
+	vma->vm_private_data = handle;
+	pr_debug("%s: %d client_cnt %d handle_cnt %d alloc_cnt %d\n",
+		 __func__, __LINE__,
+		 atomic_read(&client->ref.refcount),
+		 atomic_read(&handle->ref.refcount),
+		 atomic_read(&buffer->ref.refcount));
+	return 0;
+
+err1:
+	/* drop the reference to the handle */
+	ion_handle_put(handle);
+err:
+	/* drop the reference to the client */
+	ion_client_put(client);
+	return ret;
+}
+
+static const struct file_operations ion_share_fops = {
+	.owner		= THIS_MODULE,
+	.release	= ion_share_release,
+	.mmap		= ion_share_mmap,
+};
+
+static int ion_ioctl_share(struct file *parent, struct ion_client *client,
+			   struct ion_handle *handle)
+{
+	int fd = get_unused_fd();
+	struct file *file;
+
+	if (fd < 0)
+		return -ENFILE;
+
+	file = anon_inode_getfile("ion_share_fd", &ion_share_fops,
+				  handle->buffer, O_RDWR);
+	if (IS_ERR_OR_NULL(file))
+		goto err;
+	ion_buffer_get(handle->buffer);
+	fd_install(fd, file);
+
+	return fd;
+
+err:
+	put_unused_fd(fd);
+	return -ENFILE;
+}
+
+static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct ion_client *client = filp->private_data;
+
+	switch (cmd) {
+	case ION_IOC_ALLOC:
+	{
+		struct ion_allocation_data data;
+
+		if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
+			return -EFAULT;
+		data.handle = ion_alloc(client, data.len, data.align,
+					     data.flags);
+		if (copy_to_user((void __user *)arg, &data, sizeof(data)))
+			return -EFAULT;
+		break;
+	}
+	case ION_IOC_FREE:
+	{
+		struct ion_handle_data data;
+		bool valid;
+
+		if (copy_from_user(&data, (void __user *)arg,
+				   sizeof(struct ion_handle_data)))
+			return -EFAULT;
+		mutex_lock(&client->lock);
+		valid = ion_handle_validate(client, data.handle);
+		mutex_unlock(&client->lock);
+		if (!valid)
+			return -EINVAL;
+		ion_free(client, data.handle);
+		break;
+	}
+	case ION_IOC_MAP:
+	case ION_IOC_SHARE:
+	{
+		struct ion_fd_data data;
+
+		if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
+			return -EFAULT;
+		mutex_lock(&client->lock);
+		if (!ion_handle_validate(client, data.handle)) {
+			pr_err("%s: invalid handle passed to share ioctl.\n",
+			       __func__);
+			mutex_unlock(&client->lock);
+			return -EINVAL;
+		}
+		data.fd = ion_ioctl_share(filp, client, data.handle);
+		mutex_unlock(&client->lock);
+		if (copy_to_user((void __user *)arg, &data, sizeof(data)))
+			return -EFAULT;
+		break;
+	}
+	case ION_IOC_IMPORT:
+	{
+		struct ion_fd_data data;
+		if (copy_from_user(&data, (void __user *)arg,
+				   sizeof(struct ion_fd_data)))
+			return -EFAULT;
+
+		data.handle = ion_import_fd(client, data.fd);
+		if (IS_ERR(data.handle))
+			data.handle = NULL;
+		if (copy_to_user((void __user *)arg, &data,
+				 sizeof(struct ion_fd_data)))
+			return -EFAULT;
+		break;
+	}
+	case ION_IOC_CUSTOM:
+	{
+		struct ion_device *dev = client->dev;
+		struct ion_custom_data data;
+
+		if (!dev->custom_ioctl)
+			return -ENOTTY;
+		if (copy_from_user(&data, (void __user *)arg,
+				sizeof(struct ion_custom_data)))
+			return -EFAULT;
+		return dev->custom_ioctl(client, data.cmd, data.arg);
+	}
+	default:
+		return -ENOTTY;
+	}
+	return 0;
+}
+
+static int ion_release(struct inode *inode, struct file *file)
+{
+	struct ion_client *client = file->private_data;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	ion_client_put(client);
+	return 0;
+}
+
+static int ion_open(struct inode *inode, struct file *file)
+{
+	struct miscdevice *miscdev = file->private_data;
+	struct ion_device *dev = container_of(miscdev, struct ion_device, dev);
+	struct ion_client *client;
+
+	pr_debug("%s: %d\n", __func__, __LINE__);
+	client = ion_client_create(dev, -1, "user");
+	if (IS_ERR_OR_NULL(client))
+		return PTR_ERR(client);
+	file->private_data = client;
+
+	return 0;
+}
+
+static const struct file_operations ion_fops = {
+	.owner          = THIS_MODULE,
+	.open           = ion_open,
+	.release        = ion_release,
+	.unlocked_ioctl = ion_ioctl,
+};
+
+static size_t ion_debug_heap_total(struct ion_client *client,
+				   enum ion_heap_type type)
+{
+	size_t size = 0;
+	struct rb_node *n;
+
+	mutex_lock(&client->lock);
+	for (n = rb_first(&client->handles); n; n = rb_next(n)) {
+		struct ion_handle *handle = rb_entry(n,
+						     struct ion_handle,
+						     node);
+		if (handle->buffer->heap->type == type)
+			size += handle->buffer->size;
+	}
+	mutex_unlock(&client->lock);
+	return size;
+}
+
+static int ion_debug_heap_show(struct seq_file *s, void *unused)
+{
+	struct ion_heap *heap = s->private;
+	struct ion_device *dev = heap->dev;
+	struct rb_node *n;
+
+	seq_printf(s, "%16.s %16.s %16.s\n", "client", "pid", "size");
+	for (n = rb_first(&dev->user_clients); n; n = rb_next(n)) {
+		struct ion_client *client = rb_entry(n, struct ion_client,
+						     node);
+		char task_comm[TASK_COMM_LEN];
+		size_t size = ion_debug_heap_total(client, heap->type);
+		if (!size)
+			continue;
+
+		get_task_comm(task_comm, client->task);
+		seq_printf(s, "%16.s %16u %16u\n", task_comm, client->pid,
+			   size);
+	}
+
+	for (n = rb_first(&dev->kernel_clients); n; n = rb_next(n)) {
+		struct ion_client *client = rb_entry(n, struct ion_client,
+						     node);
+		size_t size = ion_debug_heap_total(client, heap->type);
+		if (!size)
+			continue;
+		seq_printf(s, "%16.s %16u %16u\n", client->name, client->pid,
+			   size);
+	}
+	return 0;
+}
+
+static int ion_debug_heap_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, ion_debug_heap_show, inode->i_private);
+}
+
+static const struct file_operations debug_heap_fops = {
+	.open = ion_debug_heap_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
+{
+	struct rb_node **p = &dev->heaps.rb_node;
+	struct rb_node *parent = NULL;
+	struct ion_heap *entry;
+
+	heap->dev = dev;
+	mutex_lock(&dev->lock);
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct ion_heap, node);
+
+		if (heap->id < entry->id) {
+			p = &(*p)->rb_left;
+		} else if (heap->id > entry->id ) {
+			p = &(*p)->rb_right;
+		} else {
+			pr_err("%s: can not insert multiple heaps with "
+				"id %d\n", __func__, heap->id);
+			goto end;
+		}
+	}
+
+	rb_link_node(&heap->node, parent, p);
+	rb_insert_color(&heap->node, &dev->heaps);
+	debugfs_create_file(heap->name, 0664, dev->debug_root, heap,
+			    &debug_heap_fops);
+end:
+	mutex_unlock(&dev->lock);
+}
+
+struct ion_device *ion_device_create(long (*custom_ioctl)
+				     (struct ion_client *client,
+				      unsigned int cmd,
+				      unsigned long arg))
+{
+	struct ion_device *idev;
+	int ret;
+
+	idev = kzalloc(sizeof(struct ion_device), GFP_KERNEL);
+	if (!idev)
+		return ERR_PTR(-ENOMEM);
+
+	idev->dev.minor = MISC_DYNAMIC_MINOR;
+	idev->dev.name = "ion";
+	idev->dev.fops = &ion_fops;
+	idev->dev.parent = NULL;
+	ret = misc_register(&idev->dev);
+	if (ret) {
+		pr_err("ion: failed to register misc device.\n");
+		return ERR_PTR(ret);
+	}
+
+	idev->debug_root = debugfs_create_dir("ion", NULL);
+	if (IS_ERR_OR_NULL(idev->debug_root))
+		pr_err("ion: failed to create debug files.\n");
+
+	idev->custom_ioctl = custom_ioctl;
+	idev->buffers = RB_ROOT;
+	mutex_init(&idev->lock);
+	idev->heaps = RB_ROOT;
+	idev->user_clients = RB_ROOT;
+	idev->kernel_clients = RB_ROOT;
+	return idev;
+}
+
+void ion_device_destroy(struct ion_device *dev)
+{
+	misc_deregister(&dev->dev);
+	/* XXX need to free the heaps and clients ? */
+	kfree(dev);
+}

drivers/staging/android/ion/ion.h

···
+/*
+ * drivers/staging/android/ion/ion.h
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _LINUX_ION_H
+#define _LINUX_ION_H
+
+#include <linux/types.h>
+
+struct ion_handle;
+/**
+ * enum ion_heap_types - list of all possible types of heaps
+ * @ION_HEAP_TYPE_SYSTEM:	 memory allocated via vmalloc
+ * @ION_HEAP_TYPE_SYSTEM_CONTIG: memory allocated via kmalloc
+ * @ION_HEAP_TYPE_CARVEOUT:	 memory allocated from a prereserved
+ * 				 carveout heap, allocations are physically
+ * 				 contiguous
+ * @ION_HEAP_END:		 helper for iterating over heaps
+ */
+enum ion_heap_type {
+	ION_HEAP_TYPE_SYSTEM,
+	ION_HEAP_TYPE_SYSTEM_CONTIG,
+	ION_HEAP_TYPE_CARVEOUT,
+	ION_HEAP_TYPE_CUSTOM, /* must be last so device specific heaps always
+				 are at the end of this enum */
+	ION_NUM_HEAPS,
+};
+
+#define ION_HEAP_SYSTEM_MASK		(1 << ION_HEAP_TYPE_SYSTEM)
+#define ION_HEAP_SYSTEM_CONTIG_MASK	(1 << ION_HEAP_TYPE_SYSTEM_CONTIG)
+#define ION_HEAP_CARVEOUT_MASK		(1 << ION_HEAP_TYPE_CARVEOUT)
+
+#ifdef __KERNEL__
+struct ion_device;
+struct ion_heap;
+struct ion_mapper;
+struct ion_client;
+struct ion_buffer;
+
+/* This should be removed some day when phys_addr_t's are fully
+   plumbed in the kernel, and all instances of ion_phys_addr_t should
+   be converted to phys_addr_t.  For the time being many kernel interfaces
+   do not accept phys_addr_t's that would have to */
+#define ion_phys_addr_t unsigned long
+
+/**
+ * struct ion_platform_heap - defines a heap in the given platform
+ * @type:	type of the heap from ion_heap_type enum
+ * @id:		unique identifier for heap.  When allocating (lower numbers 
+ * 		will be allocated from first)
+ * @name:	used for debug purposes
+ * @base:	base address of heap in physical memory if applicable
+ * @size:	size of the heap in bytes if applicable
+ *
+ * Provided by the board file.
+ */
+struct ion_platform_heap {
+	enum ion_heap_type type;
+	unsigned int id;
+	const char *name;
+	ion_phys_addr_t base;
+	size_t size;
+};
+
+/**
+ * struct ion_platform_data - array of platform heaps passed from board file
+ * @nr:		number of structures in the array
+ * @heaps:	array of platform_heap structions
+ *
+ * Provided by the board file in the form of platform data to a platform device.
+ */
+struct ion_platform_data {
+	int nr;
+	struct ion_platform_heap heaps[];
+};
+
+/**
+ * ion_client_create() -  allocate a client and returns it
+ * @dev:	the global ion device
+ * @heap_mask:	mask of heaps this client can allocate from
+ * @name:	used for debugging
+ */
+struct ion_client *ion_client_create(struct ion_device *dev,
+				     unsigned int heap_mask, const char *name);
+
+/**
+ * ion_client_destroy() -  free's a client and all it's handles
+ * @client:	the client
+ *
+ * Free the provided client and all it's resources including
+ * any handles it is holding.
+ */
+void ion_client_destroy(struct ion_client *client);
+
+/**
+ * ion_alloc - allocate ion memory
+ * @client:	the client
+ * @len:	size of the allocation
+ * @align:	requested allocation alignment, lots of hardware blocks have
+ *		alignment requirements of some kind
+ * @flags:	mask of heaps to allocate from, if multiple bits are set
+ *		heaps will be tried in order from lowest to highest order bit
+ *
+ * Allocate memory in one of the heaps provided in heap mask and return
+ * an opaque handle to it.
+ */
+struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
+			     size_t align, unsigned int flags);
+
+/**
+ * ion_free - free a handle
+ * @client:	the client
+ * @handle:	the handle to free
+ *
+ * Free the provided handle.
+ */
+void ion_free(struct ion_client *client, struct ion_handle *handle);
+
+/**
+ * ion_phys - returns the physical address and len of a handle
+ * @client:	the client
+ * @handle:	the handle
+ * @addr:	a pointer to put the address in
+ * @len:	a pointer to put the length in
+ *
+ * This function queries the heap for a particular handle to get the
+ * handle's physical address.  It't output is only correct if
+ * a heap returns physically contiguous memory -- in other cases
+ * this api should not be implemented -- ion_map_dma should be used
+ * instead.  Returns -EINVAL if the handle is invalid.  This has
+ * no implications on the reference counting of the handle --
+ * the returned value may not be valid if the caller is not
+ * holding a reference.
+ */
+int ion_phys(struct ion_client *client, struct ion_handle *handle,
+	     ion_phys_addr_t *addr, size_t *len);
+
+/**
+ * ion_map_kernel - create mapping for the given handle
+ * @client:	the client
+ * @handle:	handle to map
+ *
+ * Map the given handle into the kernel and return a kernel address that
+ * can be used to access this address.
+ */
+void *ion_map_kernel(struct ion_client *client, struct ion_handle *handle);
+
+/**
+ * ion_unmap_kernel() - destroy a kernel mapping for a handle
+ * @client:	the client
+ * @handle:	handle to unmap
+ */
+void ion_unmap_kernel(struct ion_client *client, struct ion_handle *handle);
+
+/**
+ * ion_map_dma - create a dma mapping for a given handle
+ * @client:	the client
+ * @handle:	handle to map
+ *
+ * Return an sglist describing the given handle
+ */
+struct scatterlist *ion_map_dma(struct ion_client *client,
+				struct ion_handle *handle);
+
+/**
+ * ion_unmap_dma() - destroy a dma mapping for a handle
+ * @client:	the client
+ * @handle:	handle to unmap
+ */
+void ion_unmap_dma(struct ion_client *client, struct ion_handle *handle);
+
+/**
+ * ion_share() - given a handle, obtain a buffer to pass to other clients
+ * @client:	the client
+ * @handle:	the handle to share
+ *
+ * Given a handle, return a buffer, which exists in a global name
+ * space, and can be passed to other clients.  Should be passed into ion_import
+ * to obtain a new handle for this buffer.
+ *
+ * NOTE: This function does do not an extra reference.  The burden is on the
+ * caller to make sure the buffer doesn't go away while it's being passed to
+ * another client.  That is, ion_free should not be called on this handle until
+ * the buffer has been imported into the other client.
+ */
+struct ion_buffer *ion_share(struct ion_client *client,
+			     struct ion_handle *handle);
+
+/**
+ * ion_import() - given an buffer in another client, import it
+ * @client:	this blocks client
+ * @buffer:	the buffer to import (as obtained from ion_share)
+ *
+ * Given a buffer, add it to the client and return the handle to use to refer
+ * to it further.  This is called to share a handle from one kernel client to
+ * another.
+ */
+struct ion_handle *ion_import(struct ion_client *client,
+			      struct ion_buffer *buffer);
+
+/**
+ * ion_import_fd() - given an fd obtained via ION_IOC_SHARE ioctl, import it
+ * @client:	this blocks client
+ * @fd:		the fd
+ *
+ * A helper function for drivers that will be recieving ion buffers shared
+ * with them from userspace.  These buffers are represented by a file
+ * descriptor obtained as the return from the ION_IOC_SHARE ioctl.
+ * This function coverts that fd into the underlying buffer, and returns
+ * the handle to use to refer to it further.
+ */
+struct ion_handle *ion_import_fd(struct ion_client *client, int fd);
+#endif /* __KERNEL__ */
+
+/**
+ * DOC: Ion Userspace API
+ *
+ * create a client by opening /dev/ion
+ * most operations handled via following ioctls
+ *
+ */
+
+/**
+ * struct ion_allocation_data - metadata passed from userspace for allocations
+ * @len:	size of the allocation
+ * @align:	required alignment of the allocation
+ * @flags:	flags passed to heap
+ * @handle:	pointer that will be populated with a cookie to use to refer
+ *		to this allocation
+ *
+ * Provided by userspace as an argument to the ioctl
+ */
+struct ion_allocation_data {
+	size_t len;
+	size_t align;
+	unsigned int flags;
+	struct ion_handle *handle;
+};
+
+/**
+ * struct ion_fd_data - metadata passed to/from userspace for a handle/fd pair
+ * @handle:	a handle
+ * @fd:		a file descriptor representing that handle
+ *
+ * For ION_IOC_SHARE or ION_IOC_MAP userspace populates the handle field with
+ * the handle returned from ion alloc, and the kernel returns the file
+ * descriptor to share or map in the fd field.  For ION_IOC_IMPORT, userspace
+ * provides the file descriptor and the kernel returns the handle.
+ */
+struct ion_fd_data {
+	struct ion_handle *handle;
+	int fd;
+};
+
+/**
+ * struct ion_handle_data - a handle passed to/from the kernel
+ * @handle:	a handle
+ */
+struct ion_handle_data {
+	struct ion_handle *handle;
+};
+
+/**
+ * struct ion_custom_data - metadata passed to/from userspace for a custom ioctl
+ * @cmd:	the custom ioctl function to call
+ * @arg:	additional data to pass to the custom ioctl, typically a user
+ *		pointer to a predefined structure
+ *
+ * This works just like the regular cmd and arg fields of an ioctl.
+ */
+struct ion_custom_data {
+	unsigned int cmd;
+	unsigned long arg;
+};
+
+#define ION_IOC_MAGIC		'I'
+
+/**
+ * DOC: ION_IOC_ALLOC - allocate memory
+ *
+ * Takes an ion_allocation_data struct and returns it with the handle field
+ * populated with the opaque handle for the allocation.
+ */
+#define ION_IOC_ALLOC		_IOWR(ION_IOC_MAGIC, 0, \
+				      struct ion_allocation_data)
+
+/**
+ * DOC: ION_IOC_FREE - free memory
+ *
+ * Takes an ion_handle_data struct and frees the handle.
+ */
+#define ION_IOC_FREE		_IOWR(ION_IOC_MAGIC, 1, struct ion_handle_data)
+
+/**
+ * DOC: ION_IOC_MAP - get a file descriptor to mmap
+ *
+ * Takes an ion_fd_data struct with the handle field populated with a valid
+ * opaque handle.  Returns the struct with the fd field set to a file
+ * descriptor open in the current address space.  This file descriptor
+ * can then be used as an argument to mmap.
+ */
+#define ION_IOC_MAP		_IOWR(ION_IOC_MAGIC, 2, struct ion_fd_data)
+
+/**
+ * DOC: ION_IOC_SHARE - creates a file descriptor to use to share an allocation
+ *
+ * Takes an ion_fd_data struct with the handle field populated with a valid
+ * opaque handle.  Returns the struct with the fd field set to a file
+ * descriptor open in the current address space.  This file descriptor
+ * can then be passed to another process.  The corresponding opaque handle can
+ * be retrieved via ION_IOC_IMPORT.
+ */
+#define ION_IOC_SHARE		_IOWR(ION_IOC_MAGIC, 4, struct ion_fd_data)
+
+/**
+ * DOC: ION_IOC_IMPORT - imports a shared file descriptor
+ *
+ * Takes an ion_fd_data struct with the fd field populated with a valid file
+ * descriptor obtained from ION_IOC_SHARE and returns the struct with the handle
+ * filed set to the corresponding opaque handle.
+ */
+#define ION_IOC_IMPORT		_IOWR(ION_IOC_MAGIC, 5, int)
+
+/**
+ * DOC: ION_IOC_CUSTOM - call architecture specific ion ioctl
+ *
+ * Takes the argument of the architecture specific ioctl to call and
+ * passes appropriate userdata for that ioctl
+ */
+#define ION_IOC_CUSTOM		_IOWR(ION_IOC_MAGIC, 6, struct ion_custom_data)
+
+#endif /* _LINUX_ION_H */

drivers/staging/android/ion/ion_carveout_heap.c

···
+/*
+ * drivers/staging/android/ion/ion_carveout_heap.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+#include <linux/spinlock.h>
+
+#include <linux/err.h>
+#include <linux/genalloc.h>
+#include <linux/io.h>
+#include <linux/mm.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include "ion.h"
+#include "ion_priv.h"
+
+#include <asm/mach/map.h>
+
+struct ion_carveout_heap {
+	struct ion_heap heap;
+	struct gen_pool *pool;
+	ion_phys_addr_t base;
+};
+
+ion_phys_addr_t ion_carveout_allocate(struct ion_heap *heap,
+				      unsigned long size,
+				      unsigned long align)
+{
+	struct ion_carveout_heap *carveout_heap =
+		container_of(heap, struct ion_carveout_heap, heap);
+	unsigned long offset = gen_pool_alloc(carveout_heap->pool, size);
+
+	if (!offset)
+		return ION_CARVEOUT_ALLOCATE_FAIL;
+
+	return offset;
+}
+
+void ion_carveout_free(struct ion_heap *heap, ion_phys_addr_t addr,
+		       unsigned long size)
+{
+	struct ion_carveout_heap *carveout_heap =
+		container_of(heap, struct ion_carveout_heap, heap);
+
+	if (addr == ION_CARVEOUT_ALLOCATE_FAIL)
+		return;
+	gen_pool_free(carveout_heap->pool, addr, size);
+}
+
+static int ion_carveout_heap_phys(struct ion_heap *heap,
+				  struct ion_buffer *buffer,
+				  ion_phys_addr_t *addr, size_t *len)
+{
+	*addr = buffer->priv_phys;
+	*len = buffer->size;
+	return 0;
+}
+
+static int ion_carveout_heap_allocate(struct ion_heap *heap,
+				      struct ion_buffer *buffer,
+				      unsigned long size, unsigned long align,
+				      unsigned long flags)
+{
+	buffer->priv_phys = ion_carveout_allocate(heap, size, align);
+	return buffer->priv_phys == ION_CARVEOUT_ALLOCATE_FAIL ? -ENOMEM : 0;
+}
+
+static void ion_carveout_heap_free(struct ion_buffer *buffer)
+{
+	struct ion_heap *heap = buffer->heap;
+
+	ion_carveout_free(heap, buffer->priv_phys, buffer->size);
+	buffer->priv_phys = ION_CARVEOUT_ALLOCATE_FAIL;
+}
+
+struct scatterlist *ion_carveout_heap_map_dma(struct ion_heap *heap,
+					      struct ion_buffer *buffer)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+void ion_carveout_heap_unmap_dma(struct ion_heap *heap,
+				 struct ion_buffer *buffer)
+{
+	return;
+}
+
+void *ion_carveout_heap_map_kernel(struct ion_heap *heap,
+				   struct ion_buffer *buffer)
+{
+	return __arch_ioremap(buffer->priv_phys, buffer->size,
+			      MT_MEMORY_NONCACHED);
+}
+
+void ion_carveout_heap_unmap_kernel(struct ion_heap *heap,
+				    struct ion_buffer *buffer)
+{
+	__arch_iounmap(buffer->vaddr);
+	buffer->vaddr = NULL;
+	return;
+}
+
+int ion_carveout_heap_map_user(struct ion_heap *heap, struct ion_buffer *buffer,
+			       struct vm_area_struct *vma)
+{
+	return remap_pfn_range(vma, vma->vm_start,
+			       __phys_to_pfn(buffer->priv_phys) + vma->vm_pgoff,
+			       buffer->size,
+			       pgprot_noncached(vma->vm_page_prot));
+}
+
+static struct ion_heap_ops carveout_heap_ops = {
+	.allocate = ion_carveout_heap_allocate,
+	.free = ion_carveout_heap_free,
+	.phys = ion_carveout_heap_phys,
+	.map_user = ion_carveout_heap_map_user,
+	.map_kernel = ion_carveout_heap_map_kernel,
+	.unmap_kernel = ion_carveout_heap_unmap_kernel,
+};
+
+struct ion_heap *ion_carveout_heap_create(struct ion_platform_heap *heap_data)
+{
+	struct ion_carveout_heap *carveout_heap;
+
+	carveout_heap = kzalloc(sizeof(struct ion_carveout_heap), GFP_KERNEL);
+	if (!carveout_heap)
+		return ERR_PTR(-ENOMEM);
+
+	carveout_heap->pool = gen_pool_create(12, -1);
+	if (!carveout_heap->pool) {
+		kfree(carveout_heap);
+		return ERR_PTR(-ENOMEM);
+	}
+	carveout_heap->base = heap_data->base;
+	gen_pool_add(carveout_heap->pool, carveout_heap->base, heap_data->size,
+		     -1);
+	carveout_heap->heap.ops = &carveout_heap_ops;
+	carveout_heap->heap.type = ION_HEAP_TYPE_CARVEOUT;
+
+	return &carveout_heap->heap;
+}
+
+void ion_carveout_heap_destroy(struct ion_heap *heap)
+{
+	struct ion_carveout_heap *carveout_heap =
+	     container_of(heap, struct  ion_carveout_heap, heap);
+
+	gen_pool_destroy(carveout_heap->pool);
+	kfree(carveout_heap);
+	carveout_heap = NULL;
+}

drivers/staging/android/ion/ion_heap.c

···
+/*
+ * drivers/staging/android/ion/ion_heap.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/err.h>
+#include "ion.h"
+#include "ion_priv.h"
+
+struct ion_heap *ion_heap_create(struct ion_platform_heap *heap_data)
+{
+	struct ion_heap *heap = NULL;
+
+	switch (heap_data->type) {
+	case ION_HEAP_TYPE_SYSTEM_CONTIG:
+		heap = ion_system_contig_heap_create(heap_data);
+		break;
+	case ION_HEAP_TYPE_SYSTEM:
+		heap = ion_system_heap_create(heap_data);
+		break;
+	case ION_HEAP_TYPE_CARVEOUT:
+		heap = ion_carveout_heap_create(heap_data);
+		break;
+	default:
+		pr_err("%s: Invalid heap type %d\n", __func__,
+		       heap_data->type);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (IS_ERR_OR_NULL(heap)) {
+		pr_err("%s: error creating heap %s type %d base %lu size %u\n",
+		       __func__, heap_data->name, heap_data->type,
+		       heap_data->base, heap_data->size);
+		return ERR_PTR(-EINVAL);
+	}
+
+	heap->name = heap_data->name;
+	heap->id = heap_data->id;
+	return heap;
+}
+
+void ion_heap_destroy(struct ion_heap *heap)
+{
+	if (!heap)
+		return;
+
+	switch (heap->type) {
+	case ION_HEAP_TYPE_SYSTEM_CONTIG:
+		ion_system_contig_heap_destroy(heap);
+		break;
+	case ION_HEAP_TYPE_SYSTEM:
+		ion_system_heap_destroy(heap);
+		break;
+	case ION_HEAP_TYPE_CARVEOUT:
+		ion_carveout_heap_destroy(heap);
+		break;
+	default:
+		pr_err("%s: Invalid heap type %d\n", __func__,
+		       heap->type);
+	}
+}

drivers/staging/android/ion/ion_priv.h

···
+/*
+ * drivers/staging/android/ion/ion_priv.h
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _ION_PRIV_H
+#define _ION_PRIV_H
+
+#include <linux/kref.h>
+#include <linux/mm_types.h>
+#include <linux/mutex.h>
+#include <linux/rbtree.h>
+
+#include "ion.h"
+
+struct ion_mapping;
+
+struct ion_dma_mapping {
+	struct kref ref;
+	struct scatterlist *sglist;
+};
+
+struct ion_kernel_mapping {
+	struct kref ref;
+	void *vaddr;
+};
+
+struct ion_buffer *ion_handle_buffer(struct ion_handle *handle);
+
+/**
+ * struct ion_buffer - metadata for a particular buffer
+ * @ref:		refernce count
+ * @node:		node in the ion_device buffers tree
+ * @dev:		back pointer to the ion_device
+ * @heap:		back pointer to the heap the buffer came from
+ * @flags:		buffer specific flags
+ * @size:		size of the buffer
+ * @priv_virt:		private data to the buffer representable as
+ *			a void *
+ * @priv_phys:		private data to the buffer representable as
+ *			an ion_phys_addr_t (and someday a phys_addr_t)
+ * @lock:		protects the buffers cnt fields
+ * @kmap_cnt:		number of times the buffer is mapped to the kernel
+ * @vaddr:		the kenrel mapping if kmap_cnt is not zero
+ * @dmap_cnt:		number of times the buffer is mapped for dma
+ * @sglist:		the scatterlist for the buffer is dmap_cnt is not zero
+*/
+struct ion_buffer {
+	struct kref ref;
+	struct rb_node node;
+	struct ion_device *dev;
+	struct ion_heap *heap;
+	unsigned long flags;
+	size_t size;
+	union {
+		void *priv_virt;
+		ion_phys_addr_t priv_phys;
+	};
+	struct mutex lock;
+	int kmap_cnt;
+	void *vaddr;
+	int dmap_cnt;
+	struct scatterlist *sglist;
+};
+
+/**
+ * struct ion_heap_ops - ops to operate on a given heap
+ * @allocate:		allocate memory
+ * @free:		free memory
+ * @phys		get physical address of a buffer (only define on
+ *			physically contiguous heaps)
+ * @map_dma		map the memory for dma to a scatterlist
+ * @unmap_dma		unmap the memory for dma
+ * @map_kernel		map memory to the kernel
+ * @unmap_kernel	unmap memory to the kernel
+ * @map_user		map memory to userspace
+ */
+struct ion_heap_ops {
+	int (*allocate) (struct ion_heap *heap,
+			 struct ion_buffer *buffer, unsigned long len,
+			 unsigned long align, unsigned long flags);
+	void (*free) (struct ion_buffer *buffer);
+	int (*phys) (struct ion_heap *heap, struct ion_buffer *buffer,
+		     ion_phys_addr_t *addr, size_t *len);
+	struct scatterlist *(*map_dma) (struct ion_heap *heap,
+					struct ion_buffer *buffer);
+	void (*unmap_dma) (struct ion_heap *heap, struct ion_buffer *buffer);
+	void * (*map_kernel) (struct ion_heap *heap, struct ion_buffer *buffer);
+	void (*unmap_kernel) (struct ion_heap *heap, struct ion_buffer *buffer);
+	int (*map_user) (struct ion_heap *mapper, struct ion_buffer *buffer,
+			 struct vm_area_struct *vma);
+};
+
+/**
+ * struct ion_heap - represents a heap in the system
+ * @node:		rb node to put the heap on the device's tree of heaps
+ * @dev:		back pointer to the ion_device
+ * @type:		type of heap
+ * @ops:		ops struct as above
+ * @id:			id of heap, also indicates priority of this heap when
+ *			allocating.  These are specified by platform data and
+ *			MUST be unique
+ * @name:		used for debugging
+ *
+ * Represents a pool of memory from which buffers can be made.  In some
+ * systems the only heap is regular system memory allocated via vmalloc.
+ * On others, some blocks might require large physically contiguous buffers
+ * that are allocated from a specially reserved heap.
+ */
+struct ion_heap {
+	struct rb_node node;
+	struct ion_device *dev;
+	enum ion_heap_type type;
+	struct ion_heap_ops *ops;
+	int id;
+	const char *name;
+};
+
+/**
+ * ion_device_create - allocates and returns an ion device
+ * @custom_ioctl:	arch specific ioctl function if applicable
+ *
+ * returns a valid device or -PTR_ERR
+ */
+struct ion_device *ion_device_create(long (*custom_ioctl)
+				     (struct ion_client *client,
+				      unsigned int cmd,
+				      unsigned long arg));
+
+/**
+ * ion_device_destroy - free and device and it's resource
+ * @dev:		the device
+ */
+void ion_device_destroy(struct ion_device *dev);
+
+/**
+ * ion_device_add_heap - adds a heap to the ion device
+ * @dev:		the device
+ * @heap:		the heap to add
+ */
+void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap);
+
+/**
+ * functions for creating and destroying the built in ion heaps.
+ * architectures can add their own custom architecture specific
+ * heaps as appropriate.
+ */
+
+struct ion_heap *ion_heap_create(struct ion_platform_heap *);
+void ion_heap_destroy(struct ion_heap *);
+
+struct ion_heap *ion_system_heap_create(struct ion_platform_heap *);
+void ion_system_heap_destroy(struct ion_heap *);
+
+struct ion_heap *ion_system_contig_heap_create(struct ion_platform_heap *);
+void ion_system_contig_heap_destroy(struct ion_heap *);
+
+struct ion_heap *ion_carveout_heap_create(struct ion_platform_heap *);
+void ion_carveout_heap_destroy(struct ion_heap *);
+/**
+ * kernel api to allocate/free from carveout -- used when carveout is
+ * used to back an architecture specific custom heap
+ */
+ion_phys_addr_t ion_carveout_allocate(struct ion_heap *heap, unsigned long size,
+				      unsigned long align);
+void ion_carveout_free(struct ion_heap *heap, ion_phys_addr_t addr,
+		       unsigned long size);
+/**
+ * The carveout heap returns physical addresses, since 0 may be a valid
+ * physical address, this is used to indicate allocation failed
+ */
+#define ION_CARVEOUT_ALLOCATE_FAIL -1
+
+#endif /* _ION_PRIV_H */

drivers/staging/android/ion/ion_system_heap.c

···
+/*
+ * drivers/staging/android/ion/ion_system_heap.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include "ion.h"
+#include "ion_priv.h"
+
+static int ion_system_heap_allocate(struct ion_heap *heap,
+				     struct ion_buffer *buffer,
+				     unsigned long size, unsigned long align,
+				     unsigned long flags)
+{
+	buffer->priv_virt = vmalloc_user(size);
+	if (!buffer->priv_virt)
+		return -ENOMEM;
+	return 0;
+}
+
+void ion_system_heap_free(struct ion_buffer *buffer)
+{
+	vfree(buffer->priv_virt);
+}
+
+struct scatterlist *ion_system_heap_map_dma(struct ion_heap *heap,
+					    struct ion_buffer *buffer)
+{
+	struct scatterlist *sglist;
+	struct page *page;
+	int i;
+	int npages = PAGE_ALIGN(buffer->size) / PAGE_SIZE;
+	void *vaddr = buffer->priv_virt;
+
+	sglist = vmalloc(npages * sizeof(struct scatterlist));
+	if (!sglist)
+		return ERR_PTR(-ENOMEM);
+	memset(sglist, 0, npages * sizeof(struct scatterlist));
+	sg_init_table(sglist, npages);
+	for (i = 0; i < npages; i++) {
+		page = vmalloc_to_page(vaddr);
+		if (!page)
+			goto end;
+		sg_set_page(&sglist[i], page, PAGE_SIZE, 0);
+		vaddr += PAGE_SIZE;
+	}
+	/* XXX do cache maintenance for dma? */
+	return sglist;
+end:
+	vfree(sglist);
+	return NULL;
+}
+
+void ion_system_heap_unmap_dma(struct ion_heap *heap,
+			       struct ion_buffer *buffer)
+{
+	/* XXX undo cache maintenance for dma? */
+	if (buffer->sglist)
+		vfree(buffer->sglist);
+}
+
+void *ion_system_heap_map_kernel(struct ion_heap *heap,
+				 struct ion_buffer *buffer)
+{
+	return buffer->priv_virt;
+}
+
+void ion_system_heap_unmap_kernel(struct ion_heap *heap,
+				  struct ion_buffer *buffer)
+{
+}
+
+int ion_system_heap_map_user(struct ion_heap *heap, struct ion_buffer *buffer,
+			     struct vm_area_struct *vma)
+{
+	return remap_vmalloc_range(vma, buffer->priv_virt, vma->vm_pgoff);
+}
+
+static struct ion_heap_ops vmalloc_ops = {
+	.allocate = ion_system_heap_allocate,
+	.free = ion_system_heap_free,
+	.map_dma = ion_system_heap_map_dma,
+	.unmap_dma = ion_system_heap_unmap_dma,
+	.map_kernel = ion_system_heap_map_kernel,
+	.unmap_kernel = ion_system_heap_unmap_kernel,
+	.map_user = ion_system_heap_map_user,
+};
+
+struct ion_heap *ion_system_heap_create(struct ion_platform_heap *unused)
+{
+	struct ion_heap *heap;
+
+	heap = kzalloc(sizeof(struct ion_heap), GFP_KERNEL);
+	if (!heap)
+		return ERR_PTR(-ENOMEM);
+	heap->ops = &vmalloc_ops;
+	heap->type = ION_HEAP_TYPE_SYSTEM;
+	return heap;
+}
+
+void ion_system_heap_destroy(struct ion_heap *heap)
+{
+	kfree(heap);
+}
+
+static int ion_system_contig_heap_allocate(struct ion_heap *heap,
+					   struct ion_buffer *buffer,
+					   unsigned long len,
+					   unsigned long align,
+					   unsigned long flags)
+{
+	buffer->priv_virt = kzalloc(len, GFP_KERNEL);
+	if (!buffer->priv_virt)
+		return -ENOMEM;
+	return 0;
+}
+
+void ion_system_contig_heap_free(struct ion_buffer *buffer)
+{
+	kfree(buffer->priv_virt);
+}
+
+static int ion_system_contig_heap_phys(struct ion_heap *heap,
+				       struct ion_buffer *buffer,
+				       ion_phys_addr_t *addr, size_t *len)
+{
+	*addr = virt_to_phys(buffer->priv_virt);
+	*len = buffer->size;
+	return 0;
+}
+
+struct scatterlist *ion_system_contig_heap_map_dma(struct ion_heap *heap,
+						   struct ion_buffer *buffer)
+{
+	struct scatterlist *sglist;
+
+	sglist = vmalloc(sizeof(struct scatterlist));
+	if (!sglist)
+		return ERR_PTR(-ENOMEM);
+	sg_init_table(sglist, 1);
+	sg_set_page(sglist, virt_to_page(buffer->priv_virt), buffer->size, 0);
+	return sglist;
+}
+
+int ion_system_contig_heap_map_user(struct ion_heap *heap,
+				    struct ion_buffer *buffer,
+				    struct vm_area_struct *vma)
+{
+	unsigned long pfn = __phys_to_pfn(virt_to_phys(buffer->priv_virt));
+	return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
+			       vma->vm_end - vma->vm_start,
+			       vma->vm_page_prot);
+
+}
+
+static struct ion_heap_ops kmalloc_ops = {
+	.allocate = ion_system_contig_heap_allocate,
+	.free = ion_system_contig_heap_free,
+	.phys = ion_system_contig_heap_phys,
+	.map_dma = ion_system_contig_heap_map_dma,
+	.unmap_dma = ion_system_heap_unmap_dma,
+	.map_kernel = ion_system_heap_map_kernel,
+	.unmap_kernel = ion_system_heap_unmap_kernel,
+	.map_user = ion_system_contig_heap_map_user,
+};
+
+struct ion_heap *ion_system_contig_heap_create(struct ion_platform_heap *unused)
+{
+	struct ion_heap *heap;
+
+	heap = kzalloc(sizeof(struct ion_heap), GFP_KERNEL);
+	if (!heap)
+		return ERR_PTR(-ENOMEM);
+	heap->ops = &kmalloc_ops;
+	heap->type = ION_HEAP_TYPE_SYSTEM_CONTIG;
+	return heap;
+}
+
+void ion_system_contig_heap_destroy(struct ion_heap *heap)
+{
+	kfree(heap);
+}
+

drivers/staging/android/ion/ion_system_mapper.c

···
+/*
+ * drivers/staging/android/ion/ion_system_mapper.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include "ion.h"
+#include "ion_priv.h"
+/*
+ * This mapper is valid for any heap that allocates memory that already has
+ * a kernel mapping, this includes vmalloc'd memory, kmalloc'd memory,
+ * pages obtained via io_remap, etc.
+ */
+static void *ion_kernel_mapper_map(struct ion_mapper *mapper,
+				   struct ion_buffer *buffer,
+				   struct ion_mapping **mapping)
+{
+	if (!((1 << buffer->heap->type) & mapper->heap_mask)) {
+		pr_err("%s: attempting to map an unsupported heap\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	/* XXX REVISIT ME!!! */
+	*((unsigned long *)mapping) = (unsigned long)buffer->priv;
+	return buffer->priv;
+}
+
+static void ion_kernel_mapper_unmap(struct ion_mapper *mapper,
+				    struct ion_buffer *buffer,
+				    struct ion_mapping *mapping)
+{
+	if (!((1 << buffer->heap->type) & mapper->heap_mask))
+		pr_err("%s: attempting to unmap an unsupported heap\n",
+		       __func__);
+}
+
+static void *ion_kernel_mapper_map_kernel(struct ion_mapper *mapper,
+					struct ion_buffer *buffer,
+					struct ion_mapping *mapping)
+{
+	if (!((1 << buffer->heap->type) & mapper->heap_mask)) {
+		pr_err("%s: attempting to unmap an unsupported heap\n",
+		       __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	return buffer->priv;
+}
+
+static int ion_kernel_mapper_map_user(struct ion_mapper *mapper,
+				      struct ion_buffer *buffer,
+				      struct vm_area_struct *vma,
+				      struct ion_mapping *mapping)
+{
+	int ret;
+
+	switch (buffer->heap->type) {
+	case ION_HEAP_KMALLOC:
+	{
+		unsigned long pfn = __phys_to_pfn(virt_to_phys(buffer->priv));
+		ret = remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
+				      vma->vm_end - vma->vm_start,
+				      vma->vm_page_prot);
+		break;
+	}
+	case ION_HEAP_VMALLOC:
+		ret = remap_vmalloc_range(vma, buffer->priv, vma->vm_pgoff);
+		break;
+	default:
+		pr_err("%s: attempting to map unsupported heap to userspace\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static struct ion_mapper_ops ops = {
+	.map = ion_kernel_mapper_map,
+	.map_kernel = ion_kernel_mapper_map_kernel,
+	.map_user = ion_kernel_mapper_map_user,
+	.unmap = ion_kernel_mapper_unmap,
+};
+
+struct ion_mapper *ion_system_mapper_create(void)
+{
+	struct ion_mapper *mapper;
+	mapper = kzalloc(sizeof(struct ion_mapper), GFP_KERNEL);
+	if (!mapper)
+		return ERR_PTR(-ENOMEM);
+	mapper->type = ION_SYSTEM_MAPPER;
+	mapper->ops = &ops;
+	mapper->heap_mask = (1 << ION_HEAP_VMALLOC) | (1 << ION_HEAP_KMALLOC);
+	return mapper;
+}
+
+void ion_system_mapper_destroy(struct ion_mapper *mapper)
+{
+	kfree(mapper);
+}
+

drivers/staging/android/ion/tegra/Makefile

···
+obj-y += tegra_ion.o

drivers/staging/android/ion/tegra/tegra_ion.c

···
+/*
+ * drivers/gpu/tegra/tegra_ion.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include "../ion.h"
+#include "../ion_priv.h"
+
+struct ion_device *idev;
+struct ion_mapper *tegra_user_mapper;
+int num_heaps;
+struct ion_heap **heaps;
+
+int tegra_ion_probe(struct platform_device *pdev)
+{
+	struct ion_platform_data *pdata = pdev->dev.platform_data;
+	int err;
+	int i;
+
+	num_heaps = pdata->nr;
+
+	heaps = kzalloc(sizeof(struct ion_heap *) * pdata->nr, GFP_KERNEL);
+
+	idev = ion_device_create(NULL);
+	if (IS_ERR_OR_NULL(idev)) {
+		kfree(heaps);
+		return PTR_ERR(idev);
+	}
+
+	/* create the heaps as specified in the board file */
+	for (i = 0; i < num_heaps; i++) {
+		struct ion_platform_heap *heap_data = &pdata->heaps[i];
+
+		heaps[i] = ion_heap_create(heap_data);
+		if (IS_ERR_OR_NULL(heaps[i])) {
+			err = PTR_ERR(heaps[i]);
+			goto err;
+		}
+		ion_device_add_heap(idev, heaps[i]);
+	}
+	platform_set_drvdata(pdev, idev);
+	return 0;
+err:
+	for (i = 0; i < num_heaps; i++) {
+		if (heaps[i])
+			ion_heap_destroy(heaps[i]);
+	}
+	kfree(heaps);
+	return err;
+}
+
+int tegra_ion_remove(struct platform_device *pdev)
+{
+	struct ion_device *idev = platform_get_drvdata(pdev);
+	int i;
+
+	ion_device_destroy(idev);
+	for (i = 0; i < num_heaps; i++)
+		ion_heap_destroy(heaps[i]);
+	kfree(heaps);
+	return 0;
+}
+
+static struct platform_driver ion_driver = {
+	.probe = tegra_ion_probe,
+	.remove = tegra_ion_remove,
+	.driver = { .name = "ion-tegra" }
+};
+
+static int __init ion_init(void)
+{
+	return platform_driver_register(&ion_driver);
+}
+
+static void __exit ion_exit(void)
+{
+	platform_driver_unregister(&ion_driver);
+}
+
+module_init(ion_init);
+module_exit(ion_exit);
+