drm/i915: Add debugfs test control files for Displayport compliance testing

This patch adds 3 debugfs files for handling Displayport compliance testing
and supercedes the previous patches that implemented debugfs support for
compliance testing. Those patches were:

- [PATCH 04/17] drm/i915: Add debugfs functions for Displayport
                          compliance testing
- [PATCH 08/17] drm/i915: Add new debugfs file for Displayport
                          compliance test control
- [PATCH 09/17] drm/i915: Add debugfs write and test param parsing
                          functions for DP test control

This new patch simplifies the debugfs implementation by places a single
test control value into an individual file. Each file is readable by
the usersapce application and the test_active file is writable to
indicate to the kernel when userspace has completed its portion of the
test sequence.

Replacing the previous files simplifies operation and speeds response
time for the user app, as it is required to poll on the test_active file
in order to determine when it needs to begin its operations.

V2:
- Updated the test active variable name to match the change in
  the initial patch of the series
V3:
- Added a fix in the test_active_write function to prevent a NULL pointer
  dereference if the encoder on the connector is invalid

Signed-off-by: Todd Previte <tprevite@gmail.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -3951,6 +3951,212 @@ static const struct file_operations i915_display_crc_ctl_fops = {
 	.write = display_crc_ctl_write
 };
 
+static ssize_t i915_displayport_test_active_write(struct file *file,
+					    const char __user *ubuf,
+					    size_t len, loff_t *offp)
+{
+	char *input_buffer;
+	int status = 0;
+	struct seq_file *m;
+	struct drm_device *dev;
+	struct drm_connector *connector;
+	struct list_head *connector_list;
+	struct intel_dp *intel_dp;
+	int val = 0;
+
+	m = file->private_data;
+	if (!m) {
+		status = -ENODEV;
+		return status;
+	}
+	dev = m->private;
+
+	if (!dev) {
+		status = -ENODEV;
+		return status;
+	}
+	connector_list = &dev->mode_config.connector_list;
+
+	if (len == 0)
+		return 0;
+
+	input_buffer = kmalloc(len + 1, GFP_KERNEL);
+	if (!input_buffer)
+		return -ENOMEM;
+
+	if (copy_from_user(input_buffer, ubuf, len)) {
+		status = -EFAULT;
+		goto out;
+	}
+
+	input_buffer[len] = '\0';
+	DRM_DEBUG_DRIVER("Copied %d bytes from user\n", (unsigned int)len);
+
+	list_for_each_entry(connector, connector_list, head) {
+
+		if (connector->connector_type !=
+		    DRM_MODE_CONNECTOR_DisplayPort)
+			continue;
+
+		if (connector->connector_type ==
+		    DRM_MODE_CONNECTOR_DisplayPort &&
+		    connector->status == connector_status_connected &&
+		    connector->encoder != NULL) {
+			intel_dp = enc_to_intel_dp(connector->encoder);
+			status = kstrtoint(input_buffer, 10, &val);
+			if (status < 0)
+				goto out;
+			DRM_DEBUG_DRIVER("Got %d for test active\n", val);
+			/* To prevent erroneous activation of the compliance
+			 * testing code, only accept an actual value of 1 here
+			 */
+			if (val == 1)
+				intel_dp->compliance_test_active = 1;
+			else
+				intel_dp->compliance_test_active = 0;
+		}
+	}
+out:
+	kfree(input_buffer);
+	if (status < 0)
+		return status;
+
+	*offp += len;
+	return len;
+}
+
+static int i915_displayport_test_active_show(struct seq_file *m, void *data)
+{
+	struct drm_device *dev = m->private;
+	struct drm_connector *connector;
+	struct list_head *connector_list = &dev->mode_config.connector_list;
+	struct intel_dp *intel_dp;
+
+	if (!dev)
+		return -ENODEV;
+
+	list_for_each_entry(connector, connector_list, head) {
+
+		if (connector->connector_type !=
+		    DRM_MODE_CONNECTOR_DisplayPort)
+			continue;
+
+		if (connector->status == connector_status_connected &&
+		    connector->encoder != NULL) {
+			intel_dp = enc_to_intel_dp(connector->encoder);
+			if (intel_dp->compliance_test_active)
+				seq_puts(m, "1");
+			else
+				seq_puts(m, "0");
+		} else
+			seq_puts(m, "0");
+	}
+
+	return 0;
+}
+
+static int i915_displayport_test_active_open(struct inode *inode,
+				       struct file *file)
+{
+	struct drm_device *dev = inode->i_private;
+
+	return single_open(file, i915_displayport_test_active_show, dev);
+}
+
+static const struct file_operations i915_displayport_test_active_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_displayport_test_active_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = i915_displayport_test_active_write
+};
+
+static int i915_displayport_test_data_show(struct seq_file *m, void *data)
+{
+	struct drm_device *dev = m->private;
+	struct drm_connector *connector;
+	struct list_head *connector_list = &dev->mode_config.connector_list;
+	struct intel_dp *intel_dp;
+
+	if (!dev)
+		return -ENODEV;
+
+	list_for_each_entry(connector, connector_list, head) {
+
+		if (connector->connector_type !=
+		    DRM_MODE_CONNECTOR_DisplayPort)
+			continue;
+
+		if (connector->status == connector_status_connected &&
+		    connector->encoder != NULL) {
+			intel_dp = enc_to_intel_dp(connector->encoder);
+			seq_printf(m, "%lx", intel_dp->compliance_test_data);
+		} else
+			seq_puts(m, "0");
+	}
+
+	return 0;
+}
+static int i915_displayport_test_data_open(struct inode *inode,
+				       struct file *file)
+{
+	struct drm_device *dev = inode->i_private;
+
+	return single_open(file, i915_displayport_test_data_show, dev);
+}
+
+static const struct file_operations i915_displayport_test_data_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_displayport_test_data_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release
+};
+
+static int i915_displayport_test_type_show(struct seq_file *m, void *data)
+{
+	struct drm_device *dev = m->private;
+	struct drm_connector *connector;
+	struct list_head *connector_list = &dev->mode_config.connector_list;
+	struct intel_dp *intel_dp;
+
+	if (!dev)
+		return -ENODEV;
+
+	list_for_each_entry(connector, connector_list, head) {
+
+		if (connector->connector_type !=
+		    DRM_MODE_CONNECTOR_DisplayPort)
+			continue;
+
+		if (connector->status == connector_status_connected &&
+		    connector->encoder != NULL) {
+			intel_dp = enc_to_intel_dp(connector->encoder);
+			seq_printf(m, "%02lx", intel_dp->compliance_test_type);
+		} else
+			seq_puts(m, "0");
+	}
+
+	return 0;
+}
+
+static int i915_displayport_test_type_open(struct inode *inode,
+				       struct file *file)
+{
+	struct drm_device *dev = inode->i_private;
+
+	return single_open(file, i915_displayport_test_type_show, dev);
+}
+
+static const struct file_operations i915_displayport_test_type_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_displayport_test_type_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release
+};
+
 static void wm_latency_show(struct seq_file *m, const uint16_t wm[8])
 {
 	struct drm_device *dev = m->private;
@@ -4846,6 +5052,9 @@ static const struct i915_debugfs_files {
 	{"i915_spr_wm_latency", &i915_spr_wm_latency_fops},
 	{"i915_cur_wm_latency", &i915_cur_wm_latency_fops},
 	{"i915_fbc_false_color", &i915_fbc_fc_fops},
+	{"i915_dp_test_data", &i915_displayport_test_data_fops},
+	{"i915_dp_test_type", &i915_displayport_test_type_fops},
+	{"i915_dp_test_active", &i915_displayport_test_active_fops}
 };
 
 void intel_display_crc_init(struct drm_device *dev)