[PATCH v6 27/36] drm/connector: hdmi: Create Infoframe DebugFS entries

[Maxime Ripard <mripard@kernel.org>]

There has been some discussions recently about the infoframes sent by
drivers and if they were properly generated.

In parallel, there's been some interest in creating an infoframe-decode
tool similar to edid-decode.

Both would be much easier if we were to expose the infoframes programmed
in the hardware. It won't be perfect since we have no guarantee that
it's actually what goes through the wire, but it's the best we can do.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/drm_debugfs.c | 110 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 08fcefd804bc..160389f3d84b 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -520,6 +520,114 @@ static const struct file_operations drm_connector_fops = {
 	.write = connector_write
 };
 
+struct debugfs_wrapper {
+	struct drm_connector *connector;
+	struct drm_connector_hdmi_infoframe *frame;
+};
+
+#define HDMI_MAX_INFOFRAME_SIZE		29
+
+static ssize_t
+infoframe_read(struct file *filp, char __user *ubuf, size_t count, loff_t *ppos)
+{
+	const struct debugfs_wrapper *wrapper = filp->private_data;
+	struct drm_connector *connector = wrapper->connector;
+	struct drm_connector_hdmi_infoframe *infoframe = wrapper->frame;
+	union hdmi_infoframe *frame = &infoframe->data;
+	u8 buf[HDMI_MAX_INFOFRAME_SIZE];
+	ssize_t len = 0;
+
+	mutex_lock(&connector->hdmi.infoframes.lock);
+
+	if (!infoframe->set)
+		goto out;
+
+	len = hdmi_infoframe_pack(frame, buf, sizeof(buf));
+	if (len < 0)
+		goto out;
+
+	len = simple_read_from_buffer(ubuf, count, ppos, buf, len);
+
+out:
+	mutex_unlock(&connector->hdmi.infoframes.lock);
+	return len;
+}
+
+static const struct file_operations infoframe_fops = {
+	.owner   = THIS_MODULE,
+	.open    = simple_open,
+	.read    = infoframe_read,
+};
+
+static int create_hdmi_infoframe_file(struct drm_connector *connector,
+				      struct dentry *parent,
+				      const char *filename,
+				      struct drm_connector_hdmi_infoframe *frame)
+{
+	struct drm_device *dev = connector->dev;
+	struct debugfs_wrapper *wrapper;
+	struct dentry *file;
+
+	wrapper = drmm_kzalloc(dev, sizeof(*wrapper), GFP_KERNEL);
+	if (!wrapper)
+		return -ENOMEM;
+
+	wrapper->connector = connector;
+	wrapper->frame = frame;
+
+	file = debugfs_create_file(filename, 0400, parent, wrapper, &infoframe_fops);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	return 0;
+}
+
+#define CREATE_HDMI_INFOFRAME_FILE(c, p, i)		\
+	create_hdmi_infoframe_file(c, p, #i, &(c)->hdmi.infoframes.i)
+
+static int create_hdmi_infoframe_files(struct drm_connector *connector,
+				       struct dentry *parent)
+{
+	int ret;
+
+	ret = CREATE_HDMI_INFOFRAME_FILE(connector, parent, audio);
+	if (ret)
+		return ret;
+
+	ret = CREATE_HDMI_INFOFRAME_FILE(connector, parent, avi);
+	if (ret)
+		return ret;
+
+	ret = CREATE_HDMI_INFOFRAME_FILE(connector, parent, hdr_drm);
+	if (ret)
+		return ret;
+
+	ret = CREATE_HDMI_INFOFRAME_FILE(connector, parent, spd);
+	if (ret)
+		return ret;
+
+	ret = CREATE_HDMI_INFOFRAME_FILE(connector, parent, hdmi);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void hdmi_debugfs_add(struct drm_connector *connector)
+{
+	struct dentry *dir;
+
+	if (!(connector->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
+	      connector->connector_type == DRM_MODE_CONNECTOR_HDMIB))
+		return;
+
+	dir = debugfs_create_dir("infoframes", connector->debugfs_entry);
+	if (IS_ERR(dir))
+		return;
+
+	create_hdmi_infoframe_files(connector, dir);
+}
+
 void drm_debugfs_connector_add(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
@@ -547,6 +655,8 @@ void drm_debugfs_connector_add(struct drm_connector *connector)
 	debugfs_create_file("output_bpc", 0444, root, connector,
 			    &output_bpc_fops);
 
+	hdmi_debugfs_add(connector);
+
 	if (connector->funcs->debugfs_init)
 		connector->funcs->debugfs_init(connector, root);
 }

-- 
2.43.0