v4.19.13 snapshot.
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
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--- /dev/null
+++ b/include/linux/dma-buf.h
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+/*
+ * Header file for dma buffer sharing framework.
+ *
+ * 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/>.
+ */
+#ifndef __DMA_BUF_H__
+#define __DMA_BUF_H__
+
+#include <linux/file.h>
+#include <linux/err.h>
+#include <linux/scatterlist.h>
+#include <linux/list.h>
+#include <linux/dma-mapping.h>
+#include <linux/fs.h>
+#include <linux/dma-fence.h>
+#include <linux/wait.h>
+
+struct device;
+struct dma_buf;
+struct dma_buf_attachment;
+
+/**
+ * struct dma_buf_ops - operations possible on struct dma_buf
+ * @map_atomic: [optional] maps a page from the buffer into kernel address
+ * space, users may not block until the subsequent unmap call.
+ * This callback must not sleep.
+ * @unmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
+ * This Callback must not sleep.
+ * @map: [optional] maps a page from the buffer into kernel address space.
+ * @unmap: [optional] unmaps a page from the buffer.
+ * @vmap: [optional] creates a virtual mapping for the buffer into kernel
+ * address space. Same restrictions as for vmap and friends apply.
+ * @vunmap: [optional] unmaps a vmap from the buffer
+ */
+struct dma_buf_ops {
+ /**
+ * @attach:
+ *
+ * This is called from dma_buf_attach() to make sure that a given
+ * &dma_buf_attachment.dev can access the provided &dma_buf. Exporters
+ * which support buffer objects in special locations like VRAM or
+ * device-specific carveout areas should check whether the buffer could
+ * be move to system memory (or directly accessed by the provided
+ * device), and otherwise need to fail the attach operation.
+ *
+ * The exporter should also in general check whether the current
+ * allocation fullfills the DMA constraints of the new device. If this
+ * is not the case, and the allocation cannot be moved, it should also
+ * fail the attach operation.
+ *
+ * Any exporter-private housekeeping data can be stored in the
+ * &dma_buf_attachment.priv pointer.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success, negative error code on failure. It might return -EBUSY
+ * to signal that backing storage is already allocated and incompatible
+ * with the requirements of requesting device.
+ */
+ int (*attach)(struct dma_buf *, struct dma_buf_attachment *);
+
+ /**
+ * @detach:
+ *
+ * This is called by dma_buf_detach() to release a &dma_buf_attachment.
+ * Provided so that exporters can clean up any housekeeping for an
+ * &dma_buf_attachment.
+ *
+ * This callback is optional.
+ */
+ void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
+
+ /**
+ * @map_dma_buf:
+ *
+ * This is called by dma_buf_map_attachment() and is used to map a
+ * shared &dma_buf into device address space, and it is mandatory. It
+ * can only be called if @attach has been called successfully. This
+ * essentially pins the DMA buffer into place, and it cannot be moved
+ * any more
+ *
+ * This call may sleep, e.g. when the backing storage first needs to be
+ * allocated, or moved to a location suitable for all currently attached
+ * devices.
+ *
+ * Note that any specific buffer attributes required for this function
+ * should get added to device_dma_parameters accessible via
+ * &device.dma_params from the &dma_buf_attachment. The @attach callback
+ * should also check these constraints.
+ *
+ * If this is being called for the first time, the exporter can now
+ * choose to scan through the list of attachments for this buffer,
+ * collate the requirements of the attached devices, and choose an
+ * appropriate backing storage for the buffer.
+ *
+ * Based on enum dma_data_direction, it might be possible to have
+ * multiple users accessing at the same time (for reading, maybe), or
+ * any other kind of sharing that the exporter might wish to make
+ * available to buffer-users.
+ *
+ * Returns:
+ *
+ * A &sg_table scatter list of or the backing storage of the DMA buffer,
+ * already mapped into the device address space of the &device attached
+ * with the provided &dma_buf_attachment.
+ *
+ * On failure, returns a negative error value wrapped into a pointer.
+ * May also return -EINTR when a signal was received while being
+ * blocked.
+ */
+ struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
+ enum dma_data_direction);
+ /**
+ * @unmap_dma_buf:
+ *
+ * This is called by dma_buf_unmap_attachment() and should unmap and
+ * release the &sg_table allocated in @map_dma_buf, and it is mandatory.
+ * It should also unpin the backing storage if this is the last mapping
+ * of the DMA buffer, it the exporter supports backing storage
+ * migration.
+ */
+ void (*unmap_dma_buf)(struct dma_buf_attachment *,
+ struct sg_table *,
+ enum dma_data_direction);
+
+ /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
+ * if the call would block.
+ */
+
+ /**
+ * @release:
+ *
+ * Called after the last dma_buf_put to release the &dma_buf, and
+ * mandatory.
+ */
+ void (*release)(struct dma_buf *);
+
+ /**
+ * @begin_cpu_access:
+ *
+ * This is called from dma_buf_begin_cpu_access() and allows the
+ * exporter to ensure that the memory is actually available for cpu
+ * access - the exporter might need to allocate or swap-in and pin the
+ * backing storage. The exporter also needs to ensure that cpu access is
+ * coherent for the access direction. The direction can be used by the
+ * exporter to optimize the cache flushing, i.e. access with a different
+ * direction (read instead of write) might return stale or even bogus
+ * data (e.g. when the exporter needs to copy the data to temporary
+ * storage).
+ *
+ * This callback is optional.
+ *
+ * FIXME: This is both called through the DMA_BUF_IOCTL_SYNC command
+ * from userspace (where storage shouldn't be pinned to avoid handing
+ * de-factor mlock rights to userspace) and for the kernel-internal
+ * users of the various kmap interfaces, where the backing storage must
+ * be pinned to guarantee that the atomic kmap calls can succeed. Since
+ * there's no in-kernel users of the kmap interfaces yet this isn't a
+ * real problem.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure. This can for
+ * example fail when the backing storage can't be allocated. Can also
+ * return -ERESTARTSYS or -EINTR when the call has been interrupted and
+ * needs to be restarted.
+ */
+ int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction);
+
+ /**
+ * @end_cpu_access:
+ *
+ * This is called from dma_buf_end_cpu_access() when the importer is
+ * done accessing the CPU. The exporter can use this to flush caches and
+ * unpin any resources pinned in @begin_cpu_access.
+ * The result of any dma_buf kmap calls after end_cpu_access is
+ * undefined.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure. Can return
+ * -ERESTARTSYS or -EINTR when the call has been interrupted and needs
+ * to be restarted.
+ */
+ int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction);
+ void *(*map)(struct dma_buf *, unsigned long);
+ void (*unmap)(struct dma_buf *, unsigned long, void *);
+
+ /**
+ * @mmap:
+ *
+ * This callback is used by the dma_buf_mmap() function
+ *
+ * Note that the mapping needs to be incoherent, userspace is expected
+ * to braket CPU access using the DMA_BUF_IOCTL_SYNC interface.
+ *
+ * Because dma-buf buffers have invariant size over their lifetime, the
+ * dma-buf core checks whether a vma is too large and rejects such
+ * mappings. The exporter hence does not need to duplicate this check.
+ * Drivers do not need to check this themselves.
+ *
+ * If an exporter needs to manually flush caches and hence needs to fake
+ * coherency for mmap support, it needs to be able to zap all the ptes
+ * pointing at the backing storage. Now linux mm needs a struct
+ * address_space associated with the struct file stored in vma->vm_file
+ * to do that with the function unmap_mapping_range. But the dma_buf
+ * framework only backs every dma_buf fd with the anon_file struct file,
+ * i.e. all dma_bufs share the same file.
+ *
+ * Hence exporters need to setup their own file (and address_space)
+ * association by setting vma->vm_file and adjusting vma->vm_pgoff in
+ * the dma_buf mmap callback. In the specific case of a gem driver the
+ * exporter could use the shmem file already provided by gem (and set
+ * vm_pgoff = 0). Exporters can then zap ptes by unmapping the
+ * corresponding range of the struct address_space associated with their
+ * own file.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure.
+ */
+ int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
+
+ void *(*vmap)(struct dma_buf *);
+ void (*vunmap)(struct dma_buf *, void *vaddr);
+};
+
+/**
+ * struct dma_buf - shared buffer object
+ * @size: size of the buffer
+ * @file: file pointer used for sharing buffers across, and for refcounting.
+ * @attachments: list of dma_buf_attachment that denotes all devices attached.
+ * @ops: dma_buf_ops associated with this buffer object.
+ * @lock: used internally to serialize list manipulation, attach/detach and vmap/unmap
+ * @vmapping_counter: used internally to refcnt the vmaps
+ * @vmap_ptr: the current vmap ptr if vmapping_counter > 0
+ * @exp_name: name of the exporter; useful for debugging.
+ * @owner: pointer to exporter module; used for refcounting when exporter is a
+ * kernel module.
+ * @list_node: node for dma_buf accounting and debugging.
+ * @priv: exporter specific private data for this buffer object.
+ * @resv: reservation object linked to this dma-buf
+ * @poll: for userspace poll support
+ * @cb_excl: for userspace poll support
+ * @cb_shared: for userspace poll support
+ *
+ * This represents a shared buffer, created by calling dma_buf_export(). The
+ * userspace representation is a normal file descriptor, which can be created by
+ * calling dma_buf_fd().
+ *
+ * Shared dma buffers are reference counted using dma_buf_put() and
+ * get_dma_buf().
+ *
+ * Device DMA access is handled by the separate &struct dma_buf_attachment.
+ */
+struct dma_buf {
+ size_t size;
+ struct file *file;
+ struct list_head attachments;
+ const struct dma_buf_ops *ops;
+ struct mutex lock;
+ unsigned vmapping_counter;
+ void *vmap_ptr;
+ const char *exp_name;
+ struct module *owner;
+ struct list_head list_node;
+ void *priv;
+ struct reservation_object *resv;
+
+ /* poll support */
+ wait_queue_head_t poll;
+
+ struct dma_buf_poll_cb_t {
+ struct dma_fence_cb cb;
+ wait_queue_head_t *poll;
+
+ __poll_t active;
+ } cb_excl, cb_shared;
+};
+
+/**
+ * struct dma_buf_attachment - holds device-buffer attachment data
+ * @dmabuf: buffer for this attachment.
+ * @dev: device attached to the buffer.
+ * @node: list of dma_buf_attachment.
+ * @priv: exporter specific attachment data.
+ *
+ * This structure holds the attachment information between the dma_buf buffer
+ * and its user device(s). The list contains one attachment struct per device
+ * attached to the buffer.
+ *
+ * An attachment is created by calling dma_buf_attach(), and released again by
+ * calling dma_buf_detach(). The DMA mapping itself needed to initiate a
+ * transfer is created by dma_buf_map_attachment() and freed again by calling
+ * dma_buf_unmap_attachment().
+ */
+struct dma_buf_attachment {
+ struct dma_buf *dmabuf;
+ struct device *dev;
+ struct list_head node;
+ void *priv;
+};
+
+/**
+ * struct dma_buf_export_info - holds information needed to export a dma_buf
+ * @exp_name: name of the exporter - useful for debugging.
+ * @owner: pointer to exporter module - used for refcounting kernel module
+ * @ops: Attach allocator-defined dma buf ops to the new buffer
+ * @size: Size of the buffer
+ * @flags: mode flags for the file
+ * @resv: reservation-object, NULL to allocate default one
+ * @priv: Attach private data of allocator to this buffer
+ *
+ * This structure holds the information required to export the buffer. Used
+ * with dma_buf_export() only.
+ */
+struct dma_buf_export_info {
+ const char *exp_name;
+ struct module *owner;
+ const struct dma_buf_ops *ops;
+ size_t size;
+ int flags;
+ struct reservation_object *resv;
+ void *priv;
+};
+
+/**
+ * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters
+ * @name: export-info name
+ *
+ * DEFINE_DMA_BUF_EXPORT_INFO macro defines the &struct dma_buf_export_info,
+ * zeroes it out and pre-populates exp_name in it.
+ */
+#define DEFINE_DMA_BUF_EXPORT_INFO(name) \
+ struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
+ .owner = THIS_MODULE }
+
+/**
+ * get_dma_buf - convenience wrapper for get_file.
+ * @dmabuf: [in] pointer to dma_buf
+ *
+ * Increments the reference count on the dma-buf, needed in case of drivers
+ * that either need to create additional references to the dmabuf on the
+ * kernel side. For example, an exporter that needs to keep a dmabuf ptr
+ * so that subsequent exports don't create a new dmabuf.
+ */
+static inline void get_dma_buf(struct dma_buf *dmabuf)
+{
+ get_file(dmabuf->file);
+}
+
+struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
+ struct device *dev);
+void dma_buf_detach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *dmabuf_attach);
+
+struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info);
+
+int dma_buf_fd(struct dma_buf *dmabuf, int flags);
+struct dma_buf *dma_buf_get(int fd);
+void dma_buf_put(struct dma_buf *dmabuf);
+
+struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
+ enum dma_data_direction);
+void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
+ enum dma_data_direction);
+int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
+ enum dma_data_direction dir);
+int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
+ enum dma_data_direction dir);
+void *dma_buf_kmap(struct dma_buf *, unsigned long);
+void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
+
+int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
+ unsigned long);
+void *dma_buf_vmap(struct dma_buf *);
+void dma_buf_vunmap(struct dma_buf *, void *vaddr);
+#endif /* __DMA_BUF_H__ */