[Intel-gfx] [RFC 2/2] drm/i915: Add a new debugfs to request HDCP version

[Ankit Nautiyal]

As per the current HDCP design, the driver selects the highest
version of HDCP that can be used to satisfy the content-protection
requirements of the user. Due to this, the content-protection
tests cannot test a lower version of HDCP, if the platform and the
display panel, both support higher HDCP version.

To provide some support for testing and debugging, a per-connector
debugfs is required to set the HDCP version via debugfs that the
kernel can consider, while enabling HDCP.

This patch adds a new debugfs entry for each connector that supports
HDCP. For enforcing a particular HDCP version for a connector, the user
can write into the debugfs for that connector.

To make design simple, the HDCP version request can only be made via
debugfs, if there is no ongoing request for Content-Protection for
the connector. The tests are expected to make sure that HDCP is disabled
before making HDCP version request via the debugfs for the connector.
Otherwise, the write request to the debugfs will be failed.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 .../drm/i915/display/intel_display_debugfs.c  | 98 +++++++++++++++++++
 1 file changed, 98 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index 70525623bcdf..e65abca1a1fa 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -2185,6 +2185,102 @@ static const struct file_operations i915_dsc_fec_support_fops = {
 	.write = i915_dsc_fec_support_write
 };
 
+static int i915_hdcp_ver_request_show(struct seq_file *m, void *data)
+{
+
+	struct drm_connector *connector = m->private;
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+	u64 hdcp_ver_flag;
+
+	if (connector->status != connector_status_connected)
+		return -ENODEV;
+
+	/* HDCP is supported by connector */
+	if (!intel_connector->hdcp.shim)
+		return -EINVAL;
+
+	hdcp_ver_flag = intel_connector->hdcp.debugfs_ver_request;
+	seq_printf(m, "HDCP_VER_FLAGS: %llu\n", hdcp_ver_flag);
+
+	seq_printf(m, "Requested Versions:\n");
+	if (hdcp_ver_flag & HDCP_VERSION_1_4)
+		seq_printf(m, "HDCP1.4\n");
+	if (hdcp_ver_flag & HDCP_VERSION_2_2)
+		seq_printf(m, "HDCP2.2\n");
+
+	return 0;
+}
+
+static int i915_hdcp_ver_request_open(struct inode *inode,
+				     struct file *file)
+{
+	return single_open(file, i915_hdcp_ver_request_show,
+			   inode->i_private);
+}
+
+static int intel_hdcp_debugfs_ver_set(struct intel_connector *connector, u64 val)
+{
+	struct intel_hdcp *hdcp = &connector->hdcp;
+
+	if (!hdcp->shim || val > HDCP_VERSION_MASK)
+		return -EINVAL;
+
+	if (hdcp->value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
+		return -EINVAL;
+
+	hdcp->debugfs_ver_request = val;
+	return 0;
+}
+
+static ssize_t i915_hdcp_ver_request_write(struct file *file,
+					  const char __user *ubuf,
+					  size_t len, loff_t *offp)
+{
+	unsigned int hdcp_ver = 0;
+	int ret;
+	struct drm_connector *connector =
+		((struct seq_file *)file->private_data)->private;
+	struct intel_connector *intel_con = to_intel_connector(connector);
+	struct drm_i915_private *i915 = to_i915(connector->dev);
+	char tmp[16];
+
+	if (len == 0)
+		return 0;
+
+	if (len >= sizeof(tmp))
+		return -EINVAL;
+
+	if (copy_from_user(tmp, ubuf, len))
+		return -EFAULT;
+
+	tmp[len] = '\0';
+
+
+	drm_dbg(&i915->drm,
+		"Copied %zu bytes from user to request hdcp ver\n", len);
+
+	ret = kstrtouint(tmp, 10, &hdcp_ver);
+	if (ret < 0)
+		return ret;
+
+	drm_dbg(&i915->drm, "Got %u for HDCP version\n", hdcp_ver);
+	ret = intel_hdcp_debugfs_ver_set(intel_con, hdcp_ver);
+	if (ret < 0)
+		return ret;
+
+	*offp += len;
+	return len;
+}
+
+static const struct file_operations i915_hdcp_ver_request_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_hdcp_ver_request_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = i915_hdcp_ver_request_write
+};
+
 /**
  * intel_connector_debugfs_add - add i915 specific connector debugfs files
  * @connector: pointer to a registered drm_connector
@@ -2215,6 +2311,8 @@ int intel_connector_debugfs_add(struct drm_connector *connector)
 	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
 		debugfs_create_file("i915_hdcp_sink_capability", S_IRUGO, root,
 				    connector, &i915_hdcp_sink_capability_fops);
+		debugfs_create_file("i915_hdcp_version_request", S_IRUGO, root,
+				    connector, &i915_hdcp_ver_request_fops);
 	}
 
 	if (INTEL_GEN(dev_priv) >= 10 &&
-- 
2.17.1