From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
While normal video/radio/vbi/swradio nodes have a proper QUERYCAP ioctl
that apps can call to determine that it is indeed a V4L2 device, there
is currently no equivalent for v4l-subdev nodes. Adding this ioctl will
solve that, and it will allow utilities like v4l2-compliance to be used
with these devices as well.
SUBDEV_QUERYCAP currently returns the version and subdev_caps of the
subdevice. Define as the initial set of subdev_caps the read-only or
read/write flags, to signal to userspace which set of IOCTLs are
available on the subdevice.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-subdev.c | 12 ++++++++++++
include/uapi/linux/v4l2-subdev.h | 18 ++++++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 174778f9c0bc4..6ae617a1e7e78 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -15,6 +15,7 @@
#include <linux/types.h>
#include <linux/videodev2.h>
#include <linux/export.h>
+#include <linux/version.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-device.h>
@@ -344,6 +345,17 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
int rval;
switch (cmd) {
+ case VIDIOC_SUBDEV_QUERYCAP: {
+ struct v4l2_subdev_capability *cap = arg;
+
+ memset(cap->reserved, 0, sizeof(cap->reserved));
+ cap->version = LINUX_VERSION_CODE;
+ cap->capabilities = ro_subdev ? V4L2_SUBDEV_CAP_RO_SUBDEV
+ : V4L2_SUBDEV_CAP_RW_SUBDEV;
+
+ return 0;
+ }
+
case VIDIOC_QUERYCTRL:
/*
* TODO: this really should be folded into v4l2_queryctrl (this
diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
index 03970ce307419..29d1874cb5e95 100644
--- a/include/uapi/linux/v4l2-subdev.h
+++ b/include/uapi/linux/v4l2-subdev.h
@@ -155,9 +155,27 @@ struct v4l2_subdev_selection {
__u32 reserved[8];
};
+/**
+ * struct v4l2_subdev_capability - subdev capabilities
+ * @version: the driver versioning number
+ * @capabilities: the subdev capabilities, see V4L2_SUBDEV_CAP_*
+ * @reserved: for future use, set to zero for now
+ */
+struct v4l2_subdev_capability {
+ __u32 version;
+ __u32 capabilities;
+ __u32 reserved[14];
+};
+
+/* The v4l2 sub-device video device node is registered in read-only mode. */
+#define V4L2_SUBDEV_CAP_RO_SUBDEV BIT(0)
+/* The v4l2 sub-device video device node is registered in read/write mode. */
+#define V4L2_SUBDEV_CAP_RW_SUBDEV BIT(1)
+
/* Backwards compatibility define --- to be removed */
#define v4l2_subdev_edid v4l2_edid
+#define VIDIOC_SUBDEV_QUERYCAP _IOR('V', 0, struct v4l2_subdev_capability)
#define VIDIOC_SUBDEV_G_FMT _IOWR('V', 4, struct v4l2_subdev_format)
#define VIDIOC_SUBDEV_S_FMT _IOWR('V', 5, struct v4l2_subdev_format)
#define VIDIOC_SUBDEV_G_FRAME_INTERVAL _IOWR('V', 21, struct v4l2_subdev_frame_interval)
--
2.26.1
