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combine-diff.c

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  • dma-buf.c 17.83 KiB
    /*
     * Framework for buffer objects that can be shared across devices/subsystems.
     *
     * Copyright(C) 2011 Linaro Limited. All rights reserved.
     * Author: Sumit Semwal <sumit.semwal@ti.com>
     *
     * Many thanks to linaro-mm-sig list, and specially
     * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
     * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
     * refining of this idea.
     *
     * This program is free software; you can redistribute it and/or modify it
     * under the terms of the GNU General Public License version 2 as published by
     * the Free Software Foundation.
     *
     * 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, see <http://www.gnu.org/licenses/>.
     */
    
    #include <linux/fs.h>
    #include <linux/slab.h>
    #include <linux/dma-buf.h>
    #include <linux/anon_inodes.h>
    #include <linux/export.h>
    #include <linux/debugfs.h>
    #include <linux/seq_file.h>
    
    static inline int is_dma_buf_file(struct file *);
    
    struct dma_buf_list {
    	struct list_head head;
    	struct mutex lock;
    };
    
    static struct dma_buf_list db_list;
    
    static int dma_buf_release(struct inode *inode, struct file *file)
    {
    	struct dma_buf *dmabuf;
    
    	if (!is_dma_buf_file(file))
    		return -EINVAL;
    
    	dmabuf = file->private_data;
    
    	BUG_ON(dmabuf->vmapping_counter);
    
    	dmabuf->ops->release(dmabuf);
    
    	mutex_lock(&db_list.lock);
    	list_del(&dmabuf->list_node);
    	mutex_unlock(&db_list.lock);
    
    	kfree(dmabuf);
    	return 0;
    }
    
    static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
    {
    	struct dma_buf *dmabuf;
    
    	if (!is_dma_buf_file(file))
    		return -EINVAL;
    
    	dmabuf = file->private_data;
    
    	/* check for overflowing the buffer's size */
    	if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
    	    dmabuf->size >> PAGE_SHIFT)
    		return -EINVAL;
    
    	return dmabuf->ops->mmap(dmabuf, vma);
    }
    
    static const struct file_operations dma_buf_fops = {
    	.release	= dma_buf_release,
    	.mmap		= dma_buf_mmap_internal,
    };
    
    /*
     * is_dma_buf_file - Check if struct file* is associated with dma_buf
     */
    static inline int is_dma_buf_file(struct file *file)
    {
    	return file->f_op == &dma_buf_fops;
    }
    
    /**
     * dma_buf_export_named - Creates a new dma_buf, and associates an anon file
     * with this buffer, so it can be exported.
     * Also connect the allocator specific data and ops to the buffer.
     * Additionally, provide a name string for exporter; useful in debugging.
     *
     * @priv:	[in]	Attach private data of allocator to this buffer
     * @ops:	[in]	Attach allocator-defined dma buf ops to the new buffer.
     * @size:	[in]	Size of the buffer
     * @flags:	[in]	mode flags for the file.
     * @exp_name:	[in]	name of the exporting module - useful for debugging.
     *
     * Returns, on success, a newly created dma_buf object, which wraps the
     * supplied private data and operations for dma_buf_ops. On either missing
     * ops, or error in allocating struct dma_buf, will return negative error.
     *
     */
    struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
    				size_t size, int flags, const char *exp_name)
    {
    	struct dma_buf *dmabuf;
    	struct file *file;
    
    	if (WARN_ON(!priv || !ops
    			  || !ops->map_dma_buf
    			  || !ops->unmap_dma_buf
    			  || !ops->release
    			  || !ops->kmap_atomic
    			  || !ops->kmap
    			  || !ops->mmap)) {
    		return ERR_PTR(-EINVAL);
    	}
    
    	dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
    	if (dmabuf == NULL)
    		return ERR_PTR(-ENOMEM);
    
    	dmabuf->priv = priv;
    	dmabuf->ops = ops;
    	dmabuf->size = size;
    	dmabuf->exp_name = exp_name;
    
    	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
    
    	dmabuf->file = file;
    
    	mutex_init(&dmabuf->lock);
    	INIT_LIST_HEAD(&dmabuf->attachments);
    
    	mutex_lock(&db_list.lock);
    	list_add(&dmabuf->list_node, &db_list.head);
    	mutex_unlock(&db_list.lock);
    
    	return dmabuf;
    }
    EXPORT_SYMBOL_GPL(dma_buf_export_named);
    
    
    /**
     * dma_buf_fd - returns a file descriptor for the given dma_buf
     * @dmabuf:	[in]	pointer to dma_buf for which fd is required.
     * @flags:      [in]    flags to give to fd
     *
     * On success, returns an associated 'fd'. Else, returns error.
     */
    int dma_buf_fd(struct dma_buf *dmabuf, int flags)
    {
    	int fd;
    
    	if (!dmabuf || !dmabuf->file)
    		return -EINVAL;
    
    	fd = get_unused_fd_flags(flags);
    	if (fd < 0)
    		return fd;
    
    	fd_install(fd, dmabuf->file);
    
    	return fd;
    }
    EXPORT_SYMBOL_GPL(dma_buf_fd);
    
    /**
     * dma_buf_get - returns the dma_buf structure related to an fd
     * @fd:	[in]	fd associated with the dma_buf to be returned
     *
     * On success, returns the dma_buf structure associated with an fd; uses
     * file's refcounting done by fget to increase refcount. returns ERR_PTR
     * otherwise.
     */
    struct dma_buf *dma_buf_get(int fd)
    {
    	struct file *file;
    
    	file = fget(fd);
    
    	if (!file)
    		return ERR_PTR(-EBADF);
    
    	if (!is_dma_buf_file(file)) {
    		fput(file);
    		return ERR_PTR(-EINVAL);
    	}
    
    	return file->private_data;
    }
    EXPORT_SYMBOL_GPL(dma_buf_get);
    
    /**
     * dma_buf_put - decreases refcount of the buffer
     * @dmabuf:	[in]	buffer to reduce refcount of
     *
     * Uses file's refcounting done implicitly by fput()
     */
    void dma_buf_put(struct dma_buf *dmabuf)
    {
    	if (WARN_ON(!dmabuf || !dmabuf->file))
    		return;
    
    	fput(dmabuf->file);
    }
    EXPORT_SYMBOL_GPL(dma_buf_put);
    
    /**
     * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
     * calls attach() of dma_buf_ops to allow device-specific attach functionality
     * @dmabuf:	[in]	buffer to attach device to.
     * @dev:	[in]	device to be attached.
     *
     * Returns struct dma_buf_attachment * for this attachment; may return negative
     * error codes.
     *
     */
    struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
    					  struct device *dev)
    {
    	struct dma_buf_attachment *attach;
    	int ret;
    
    	if (WARN_ON(!dmabuf || !dev))
    		return ERR_PTR(-EINVAL);
    
    	attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
    	if (attach == NULL)
    		return ERR_PTR(-ENOMEM);
    
    	attach->dev = dev;
    	attach->dmabuf = dmabuf;
    
    	mutex_lock(&dmabuf->lock);
    
    	if (dmabuf->ops->attach) {
    		ret = dmabuf->ops->attach(dmabuf, dev, attach);
    		if (ret)
    			goto err_attach;
    	}
    	list_add(&attach->node, &dmabuf->attachments);
    
    	mutex_unlock(&dmabuf->lock);
    	return attach;
    
    err_attach:
    	kfree(attach);
    	mutex_unlock(&dmabuf->lock);
    	return ERR_PTR(ret);
    }
    EXPORT_SYMBOL_GPL(dma_buf_attach);
    
    /**
     * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
     * optionally calls detach() of dma_buf_ops for device-specific detach
     * @dmabuf:	[in]	buffer to detach from.
     * @attach:	[in]	attachment to be detached; is free'd after this call.
     *
     */
    void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
    {
    	if (WARN_ON(!dmabuf || !attach))
    		return;
    
    	mutex_lock(&dmabuf->lock);
    	list_del(&attach->node);
    	if (dmabuf->ops->detach)
    		dmabuf->ops->detach(dmabuf, attach);
    
    	mutex_unlock(&dmabuf->lock);
    	kfree(attach);
    }
    EXPORT_SYMBOL_GPL(dma_buf_detach);
    
    /**
     * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
     * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
     * dma_buf_ops.
     * @attach:	[in]	attachment whose scatterlist is to be returned
     * @direction:	[in]	direction of DMA transfer
     *
     * Returns sg_table containing the scatterlist to be returned; may return NULL
     * or ERR_PTR.
     *
     */
    struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
    					enum dma_data_direction direction)
    {
    	struct sg_table *sg_table = ERR_PTR(-EINVAL);
    
    	might_sleep();
    
    	if (WARN_ON(!attach || !attach->dmabuf))
    		return ERR_PTR(-EINVAL);
    
    	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
    
    	return sg_table;
    }
    EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
    
    /**
     * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
     * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
     * dma_buf_ops.
     * @attach:	[in]	attachment to unmap buffer from
     * @sg_table:	[in]	scatterlist info of the buffer to unmap
     * @direction:  [in]    direction of DMA transfer
     *
     */
    void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
    				struct sg_table *sg_table,
    				enum dma_data_direction direction)
    {
    	might_sleep();
    
    	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
    		return;
    
    	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
    						direction);
    }
    EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
    
    
    /**
     * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
     * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
     * preparations. Coherency is only guaranteed in the specified range for the
     * specified access direction.
     * @dmabuf:	[in]	buffer to prepare cpu access for.
     * @start:	[in]	start of range for cpu access.
     * @len:	[in]	length of range for cpu access.
     * @direction:	[in]	length of range for cpu access.
     *
     * Can return negative error values, returns 0 on success.
     */
    int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
    			     enum dma_data_direction direction)
    {
    	int ret = 0;
    
    	if (WARN_ON(!dmabuf))
    		return -EINVAL;
    
    	if (dmabuf->ops->begin_cpu_access)
    		ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
    
    	return ret;
    }
    EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
    
    /**
     * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
     * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
     * actions. Coherency is only guaranteed in the specified range for the
     * specified access direction.
     * @dmabuf:	[in]	buffer to complete cpu access for.
     * @start:	[in]	start of range for cpu access.
     * @len:	[in]	length of range for cpu access.
     * @direction:	[in]	length of range for cpu access.
     *
     * This call must always succeed.
     */
    void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
    			    enum dma_data_direction direction)
    {
    	WARN_ON(!dmabuf);
    
    	if (dmabuf->ops->end_cpu_access)
    		dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
    }
    EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
    
    /**
     * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
     * space. The same restrictions as for kmap_atomic and friends apply.
     * @dmabuf:	[in]	buffer to map page from.
     * @page_num:	[in]	page in PAGE_SIZE units to map.
     *
     * This call must always succeed, any necessary preparations that might fail
     * need to be done in begin_cpu_access.
     */
    void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
    {
    	WARN_ON(!dmabuf);
    
    	return dmabuf->ops->kmap_atomic(dmabuf, page_num);
    }
    EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
    
    /**
     * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
     * @dmabuf:	[in]	buffer to unmap page from.
     * @page_num:	[in]	page in PAGE_SIZE units to unmap.
     * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap_atomic.
     *
     * This call must always succeed.
     */
    void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
    			   void *vaddr)
    {
    	WARN_ON(!dmabuf);
    
    	if (dmabuf->ops->kunmap_atomic)
    		dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
    }
    EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
    
    /**
     * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
     * same restrictions as for kmap and friends apply.
     * @dmabuf:	[in]	buffer to map page from.
     * @page_num:	[in]	page in PAGE_SIZE units to map.
     *
     * This call must always succeed, any necessary preparations that might fail
     * need to be done in begin_cpu_access.
     */
    void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
    {
    	WARN_ON(!dmabuf);
    
    	return dmabuf->ops->kmap(dmabuf, page_num);
    }
    EXPORT_SYMBOL_GPL(dma_buf_kmap);
    
    /**
     * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
     * @dmabuf:	[in]	buffer to unmap page from.
     * @page_num:	[in]	page in PAGE_SIZE units to unmap.
     * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap.
     *
     * This call must always succeed.
     */
    void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
    		    void *vaddr)
    {
    	WARN_ON(!dmabuf);
    
    	if (dmabuf->ops->kunmap)
    		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
    }
    EXPORT_SYMBOL_GPL(dma_buf_kunmap);
    
    
    /**
     * dma_buf_mmap - Setup up a userspace mmap with the given vma
     * @dmabuf:	[in]	buffer that should back the vma
     * @vma:	[in]	vma for the mmap
     * @pgoff:	[in]	offset in pages where this mmap should start within the
     * 			dma-buf buffer.
     *
     * This function adjusts the passed in vma so that it points at the file of the
     * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
     * checking on the size of the vma. Then it calls the exporters mmap function to
     * set up the mapping.
     *
     * Can return negative error values, returns 0 on success.
     */
    int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
    		 unsigned long pgoff)
    {
    	struct file *oldfile;
    	int ret;
    
    	if (WARN_ON(!dmabuf || !vma))
    		return -EINVAL;
    
    	/* check for offset overflow */
    	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
    		return -EOVERFLOW;
    
    	/* check for overflowing the buffer's size */
    	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
    	    dmabuf->size >> PAGE_SHIFT)
    		return -EINVAL;
    
    	/* readjust the vma */
    	get_file(dmabuf->file);
    	oldfile = vma->vm_file;
    	vma->vm_file = dmabuf->file;
    	vma->vm_pgoff = pgoff;
    
    	ret = dmabuf->ops->mmap(dmabuf, vma);
    	if (ret) {
    		/* restore old parameters on failure */
    		vma->vm_file = oldfile;
    		fput(dmabuf->file);
    	} else {
    		if (oldfile)
    			fput(oldfile);
    	}
    	return ret;
    
    }
    EXPORT_SYMBOL_GPL(dma_buf_mmap);
    
    /**
     * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
     * address space. Same restrictions as for vmap and friends apply.
     * @dmabuf:	[in]	buffer to vmap
     *
     * This call may fail due to lack of virtual mapping address space.
     * These calls are optional in drivers. The intended use for them
     * is for mapping objects linear in kernel space for high use objects.
     * Please attempt to use kmap/kunmap before thinking about these interfaces.
     */
    void *dma_buf_vmap(struct dma_buf *dmabuf)
    {
    	void *ptr;
    
    	if (WARN_ON(!dmabuf))
    		return NULL;
    
    	if (!dmabuf->ops->vmap)
    		return NULL;
    
    	mutex_lock(&dmabuf->lock);
    	if (dmabuf->vmapping_counter) {
    		dmabuf->vmapping_counter++;
    		BUG_ON(!dmabuf->vmap_ptr);
    		ptr = dmabuf->vmap_ptr;
    		goto out_unlock;
    	}
    
    	BUG_ON(dmabuf->vmap_ptr);
    
    	ptr = dmabuf->ops->vmap(dmabuf);
    	if (IS_ERR_OR_NULL(ptr))
    		goto out_unlock;
    
    	dmabuf->vmap_ptr = ptr;
    	dmabuf->vmapping_counter = 1;
    
    out_unlock:
    	mutex_unlock(&dmabuf->lock);
    	return ptr;
    }
    EXPORT_SYMBOL_GPL(dma_buf_vmap);
    
    /**
     * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
     * @dmabuf:	[in]	buffer to vunmap
     * @vaddr:	[in]	vmap to vunmap
     */
    void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
    {
    	if (WARN_ON(!dmabuf))
    		return;
    
    	BUG_ON(!dmabuf->vmap_ptr);
    	BUG_ON(dmabuf->vmapping_counter == 0);
    	BUG_ON(dmabuf->vmap_ptr != vaddr);
    
    	mutex_lock(&dmabuf->lock);
    	if (--dmabuf->vmapping_counter == 0) {
    		if (dmabuf->ops->vunmap)
    			dmabuf->ops->vunmap(dmabuf, vaddr);
    		dmabuf->vmap_ptr = NULL;
    	}
    	mutex_unlock(&dmabuf->lock);
    }
    EXPORT_SYMBOL_GPL(dma_buf_vunmap);
    
    #ifdef CONFIG_DEBUG_FS
    static int dma_buf_describe(struct seq_file *s)
    {
    	int ret;
    	struct dma_buf *buf_obj;
    	struct dma_buf_attachment *attach_obj;
    	int count = 0, attach_count;
    	size_t size = 0;
    
    	ret = mutex_lock_interruptible(&db_list.lock);
    
    	if (ret)
    		return ret;
    
    	seq_printf(s, "\nDma-buf Objects:\n");
    	seq_printf(s, "\texp_name\tsize\tflags\tmode\tcount\n");
    
    	list_for_each_entry(buf_obj, &db_list.head, list_node) {
    		ret = mutex_lock_interruptible(&buf_obj->lock);
    
    		if (ret) {
    			seq_printf(s,
    				  "\tERROR locking buffer object: skipping\n");
    			continue;
    		}
    
    		seq_printf(s, "\t");
    
    		seq_printf(s, "\t%s\t%08zu\t%08x\t%08x\t%08ld\n",
    				buf_obj->exp_name, buf_obj->size,
    				buf_obj->file->f_flags, buf_obj->file->f_mode,
    				(long)(buf_obj->file->f_count.counter));
    
    		seq_printf(s, "\t\tAttached Devices:\n");
    		attach_count = 0;
    
    		list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
    			seq_printf(s, "\t\t");
    
    			seq_printf(s, "%s\n", attach_obj->dev->init_name);
    			attach_count++;
    		}
    
    		seq_printf(s, "\n\t\tTotal %d devices attached\n",
    				attach_count);
    
    		count++;
    		size += buf_obj->size;
    		mutex_unlock(&buf_obj->lock);
    	}
    
    	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
    
    	mutex_unlock(&db_list.lock);
    	return 0;
    }
    
    static int dma_buf_show(struct seq_file *s, void *unused)
    {
    	void (*func)(struct seq_file *) = s->private;
    	func(s);
    	return 0;
    }
    
    static int dma_buf_debug_open(struct inode *inode, struct file *file)
    {
    	return single_open(file, dma_buf_show, inode->i_private);
    }
    
    static const struct file_operations dma_buf_debug_fops = {
    	.open           = dma_buf_debug_open,
    	.read           = seq_read,
    	.llseek         = seq_lseek,
    	.release        = single_release,
    };
    
    static struct dentry *dma_buf_debugfs_dir;
    
    static int dma_buf_init_debugfs(void)
    {
    	int err = 0;
    	dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL);
    	if (IS_ERR(dma_buf_debugfs_dir)) {
    		err = PTR_ERR(dma_buf_debugfs_dir);
    		dma_buf_debugfs_dir = NULL;
    		return err;
    	}
    
    	err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe);
    
    	if (err)
    		pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
    
    	return err;
    }
    
    static void dma_buf_uninit_debugfs(void)
    {
    	if (dma_buf_debugfs_dir)
    		debugfs_remove_recursive(dma_buf_debugfs_dir);
    }
    
    int dma_buf_debugfs_create_file(const char *name,
    				int (*write)(struct seq_file *))
    {
    	struct dentry *d;
    
    	d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
    			write, &dma_buf_debug_fops);
    
    	if (IS_ERR(d))
    		return PTR_ERR(d);
    
    	return 0;
    }
    #else
    static inline int dma_buf_init_debugfs(void)
    {
    	return 0;
    }
    static inline void dma_buf_uninit_debugfs(void)
    {
    }
    #endif
    
    static int __init dma_buf_init(void)
    {
    	mutex_init(&db_list.lock);
    	INIT_LIST_HEAD(&db_list.head);
    	dma_buf_init_debugfs();
    	return 0;
    }
    subsys_initcall(dma_buf_init);
    
    static void __exit dma_buf_deinit(void)
    {
    	dma_buf_uninit_debugfs();
    }
    __exitcall(dma_buf_deinit);