[PATCH v4 2/8] media: virtio: Add virtio-media driver structs and function declarations

[Brian Daniels <briandaniels@google.com>]

From: Alexandre Courbot <gnurou@gmail.com>

Add the structs and function declarations for the new virtio-media drvier.

Signed-off-by: Alexandre Courbot <gnurou@gmail.com>
Co-developed-by: Brian Daniels <briandaniels@google.com>
Signed-off-by: Brian Daniels <briandaniels@google.com>
---
 drivers/media/virtio/virtio_media.h | 95 +++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 drivers/media/virtio/virtio_media.h

diff --git a/drivers/media/virtio/virtio_media.h b/drivers/media/virtio/virtio_media.h
new file mode 100644
index 000000000..52809d4e9
--- /dev/null
+++ b/drivers/media/virtio/virtio_media.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0+ */
+
+/*
+ * Virtio-media structures & functions declarations.
+ *
+ * Copyright (c) 2024-2025 Google LLC.
+ */
+
+#ifndef __VIRTIO_MEDIA_H
+#define __VIRTIO_MEDIA_H
+
+#include <linux/virtio_config.h>
+#include <media/v4l2-device.h>
+
+#include "protocol.h"
+
+#define DESC_CHAIN_MAX_LEN SG_MAX_SINGLE_ALLOC
+
+#define VIRTIO_MEDIA_DEFAULT_DRIVER_NAME "virtio-media"
+
+extern char *virtio_media_driver_name;
+extern bool virtio_media_allow_userptr;
+
+/**
+ * struct virtio_media - Virtio-media device.
+ * @v4l2_dev: v4l2_device for the media device.
+ * @video_dev: video_device for the media device.
+ * @virtio_dev: virtio device for the media device.
+ * @commandq: virtio command queue.
+ * @eventq: virtio event queue.
+ * @eventq_work: work to run when events are received on @eventq.
+ * @mmap_region: region into which MMAP buffers are mapped by the host.
+ * @event_buffer: buffer for event descriptors.
+ * @sessions: list of active sessions on the device.
+ * @sessions_lock: protects @sessions and ``virtio_media_session::list``.
+ * @events_lock: prevents concurrent processing of events.
+ * @cmd: union of the device commands "open" and "munmap". The other
+ *       commands are handled by @struct virtio_media_session
+ * @resp: union of responses.to device commands "open" and "munmap". The
+ *        other responses are handled by @struct virtio_media_session
+ * @vlock: serializes access to the command queue.
+ * @wq: waitqueue for host responses on the command queue.
+ */
+struct virtio_media {
+	struct v4l2_device v4l2_dev;
+	struct video_device video_dev;
+
+	struct virtio_device *virtio_dev;
+	struct virtqueue *commandq;
+	struct virtqueue *eventq;
+	struct work_struct eventq_work;
+
+	struct virtio_shm_region mmap_region;
+
+	void *event_buffer;
+
+	struct list_head sessions;
+	struct mutex sessions_lock; /* protects sessions list */
+
+	struct mutex events_lock; /* prevents concurrent event processing */
+
+	union {
+		struct virtio_media_cmd_open open;
+		struct virtio_media_cmd_munmap munmap;
+	} cmd;
+
+	union {
+		struct virtio_media_resp_open open;
+		struct virtio_media_resp_munmap munmap;
+	} resp;
+
+	struct mutex vlock; /* serializes command queue access */
+	wait_queue_head_t wq;
+};
+
+static inline struct virtio_media *
+to_virtio_media(struct video_device *video_dev)
+{
+	return container_of(video_dev, struct virtio_media, video_dev);
+}
+
+/* virtio_media_driver.c */
+
+int virtio_media_send_command(struct virtio_media *vv, struct scatterlist **sgs,
+			      const size_t out_sgs, const size_t in_sgs,
+			      size_t minimum_resp_len, size_t *resp_len);
+void virtio_media_process_events(struct virtio_media *vv);
+
+/* virtio_media_ioctls.c */
+
+long virtio_media_device_ioctl(struct file *file, unsigned int cmd,
+			       unsigned long arg);
+extern const struct v4l2_ioctl_ops virtio_media_ioctl_ops;
+
+#endif // __VIRTIO_MEDIA_H
-- 
2.55.0.rc0.799.gd6f94ed593-goog