1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2019 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/slab.h>
9 
10 #include <drm/drm_atomic_state_helper.h>
11 #include <drm/drm_bridge.h>
12 #include <drm/drm_bridge_connector.h>
13 #include <drm/drm_connector.h>
14 #include <drm/drm_device.h>
15 #include <drm/drm_edid.h>
16 #include <drm/drm_modeset_helper_vtables.h>
17 #include <drm/drm_probe_helper.h>
18 
19 /**
20  * DOC: overview
21  *
22  * The DRM bridge connector helper object provides a DRM connector
23  * implementation that wraps a chain of &struct drm_bridge. The connector
24  * operations are fully implemented based on the operations of the bridges in
25  * the chain, and don't require any intervention from the display controller
26  * driver at runtime.
27  *
28  * To use the helper, display controller drivers create a bridge connector with
29  * a call to drm_bridge_connector_init(). This associates the newly created
30  * connector with the chain of bridges passed to the function and registers it
31  * with the DRM device. At that point the connector becomes fully usable, no
32  * further operation is needed.
33  *
34  * The DRM bridge connector operations are implemented based on the operations
35  * provided by the bridges in the chain. Each connector operation is delegated
36  * to the bridge closest to the connector (at the end of the chain) that
37  * provides the relevant functionality.
38  *
39  * To make use of this helper, all bridges in the chain shall report bridge
40  * operation flags (&drm_bridge->ops) and bridge output type
41  * (&drm_bridge->type), as well as the DRM_BRIDGE_ATTACH_NO_CONNECTOR attach
42  * flag (none of the bridges shall create a DRM connector directly).
43  */
44 
45 /**
46  * struct drm_bridge_connector - A connector backed by a chain of bridges
47  */
48 struct drm_bridge_connector {
49 	/**
50 	 * @base: The base DRM connector
51 	 */
52 	struct drm_connector base;
53 	/**
54 	 * @encoder:
55 	 *
56 	 * The encoder at the start of the bridges chain.
57 	 */
58 	struct drm_encoder *encoder;
59 	/**
60 	 * @bridge_edid:
61 	 *
62 	 * The last bridge in the chain (closest to the connector) that provides
63 	 * EDID read support, if any (see &DRM_BRIDGE_OP_EDID).
64 	 */
65 	struct drm_bridge *bridge_edid;
66 	/**
67 	 * @bridge_hpd:
68 	 *
69 	 * The last bridge in the chain (closest to the connector) that provides
70 	 * hot-plug detection notification, if any (see &DRM_BRIDGE_OP_HPD).
71 	 */
72 	struct drm_bridge *bridge_hpd;
73 	/**
74 	 * @bridge_detect:
75 	 *
76 	 * The last bridge in the chain (closest to the connector) that provides
77 	 * connector detection, if any (see &DRM_BRIDGE_OP_DETECT).
78 	 */
79 	struct drm_bridge *bridge_detect;
80 	/**
81 	 * @bridge_modes:
82 	 *
83 	 * The last bridge in the chain (closest to the connector) that provides
84 	 * connector modes detection, if any (see &DRM_BRIDGE_OP_MODES).
85 	 */
86 	struct drm_bridge *bridge_modes;
87 };
88 
89 #define to_drm_bridge_connector(x) \
90 	container_of(x, struct drm_bridge_connector, base)
91 
92 /* -----------------------------------------------------------------------------
93  * Bridge Connector Hot-Plug Handling
94  */
95 
96 static void drm_bridge_connector_hpd_notify(struct drm_connector *connector,
97 					    enum drm_connector_status status)
98 {
99 	struct drm_bridge_connector *bridge_connector =
100 		to_drm_bridge_connector(connector);
101 	struct drm_bridge *bridge;
102 
103 	/* Notify all bridges in the pipeline of hotplug events. */
104 	drm_for_each_bridge_in_chain(bridge_connector->encoder, bridge) {
105 		if (bridge->funcs->hpd_notify)
106 			bridge->funcs->hpd_notify(bridge, status);
107 	}
108 }
109 
110 static void drm_bridge_connector_hpd_cb(void *cb_data,
111 					enum drm_connector_status status)
112 {
113 	struct drm_bridge_connector *drm_bridge_connector = cb_data;
114 	struct drm_connector *connector = &drm_bridge_connector->base;
115 	struct drm_device *dev = connector->dev;
116 	enum drm_connector_status old_status;
117 
118 	mutex_lock(&dev->mode_config.mutex);
119 	old_status = connector->status;
120 	connector->status = status;
121 	mutex_unlock(&dev->mode_config.mutex);
122 
123 	if (old_status == status)
124 		return;
125 
126 	drm_bridge_connector_hpd_notify(connector, status);
127 
128 	drm_kms_helper_hotplug_event(dev);
129 }
130 
131 /**
132  * drm_bridge_connector_enable_hpd - Enable hot-plug detection for the connector
133  * @connector: The DRM bridge connector
134  *
135  * This function enables hot-plug detection for the given bridge connector.
136  * This is typically used by display drivers in their resume handler.
137  */
138 void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
139 {
140 	struct drm_bridge_connector *bridge_connector =
141 		to_drm_bridge_connector(connector);
142 	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
143 
144 	if (hpd)
145 		drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
146 				      bridge_connector);
147 }
148 EXPORT_SYMBOL_GPL(drm_bridge_connector_enable_hpd);
149 
150 /**
151  * drm_bridge_connector_disable_hpd - Disable hot-plug detection for the
152  * connector
153  * @connector: The DRM bridge connector
154  *
155  * This function disables hot-plug detection for the given bridge connector.
156  * This is typically used by display drivers in their suspend handler.
157  */
158 void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
159 {
160 	struct drm_bridge_connector *bridge_connector =
161 		to_drm_bridge_connector(connector);
162 	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
163 
164 	if (hpd)
165 		drm_bridge_hpd_disable(hpd);
166 }
167 EXPORT_SYMBOL_GPL(drm_bridge_connector_disable_hpd);
168 
169 /* -----------------------------------------------------------------------------
170  * Bridge Connector Functions
171  */
172 
173 static enum drm_connector_status
174 drm_bridge_connector_detect(struct drm_connector *connector, bool force)
175 {
176 	struct drm_bridge_connector *bridge_connector =
177 		to_drm_bridge_connector(connector);
178 	struct drm_bridge *detect = bridge_connector->bridge_detect;
179 	enum drm_connector_status status;
180 
181 	if (detect) {
182 		status = detect->funcs->detect(detect);
183 
184 		drm_bridge_connector_hpd_notify(connector, status);
185 	} else {
186 		switch (connector->connector_type) {
187 		case DRM_MODE_CONNECTOR_DPI:
188 		case DRM_MODE_CONNECTOR_LVDS:
189 		case DRM_MODE_CONNECTOR_DSI:
190 		case DRM_MODE_CONNECTOR_eDP:
191 			status = connector_status_connected;
192 			break;
193 		default:
194 			status = connector_status_unknown;
195 			break;
196 		}
197 	}
198 
199 	return status;
200 }
201 
202 static void drm_bridge_connector_destroy(struct drm_connector *connector)
203 {
204 	struct drm_bridge_connector *bridge_connector =
205 		to_drm_bridge_connector(connector);
206 
207 	if (bridge_connector->bridge_hpd) {
208 		struct drm_bridge *hpd = bridge_connector->bridge_hpd;
209 
210 		drm_bridge_hpd_disable(hpd);
211 	}
212 
213 	drm_connector_unregister(connector);
214 	drm_connector_cleanup(connector);
215 
216 	kfree(bridge_connector);
217 }
218 
219 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
220 					      struct dentry *root)
221 {
222 	struct drm_bridge_connector *bridge_connector =
223 		to_drm_bridge_connector(connector);
224 	struct drm_encoder *encoder = bridge_connector->encoder;
225 	struct drm_bridge *bridge;
226 
227 	list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
228 		if (bridge->funcs->debugfs_init)
229 			bridge->funcs->debugfs_init(bridge, root);
230 	}
231 }
232 
233 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
234 	.reset = drm_atomic_helper_connector_reset,
235 	.detect = drm_bridge_connector_detect,
236 	.fill_modes = drm_helper_probe_single_connector_modes,
237 	.destroy = drm_bridge_connector_destroy,
238 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
239 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
240 	.debugfs_init = drm_bridge_connector_debugfs_init,
241 };
242 
243 /* -----------------------------------------------------------------------------
244  * Bridge Connector Helper Functions
245  */
246 
247 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
248 					       struct drm_bridge *bridge)
249 {
250 	enum drm_connector_status status;
251 	struct edid *edid;
252 	int n;
253 
254 	status = drm_bridge_connector_detect(connector, false);
255 	if (status != connector_status_connected)
256 		goto no_edid;
257 
258 	edid = bridge->funcs->get_edid(bridge, connector);
259 	if (!drm_edid_is_valid(edid)) {
260 		kfree(edid);
261 		goto no_edid;
262 	}
263 
264 	drm_connector_update_edid_property(connector, edid);
265 	n = drm_add_edid_modes(connector, edid);
266 
267 	kfree(edid);
268 	return n;
269 
270 no_edid:
271 	drm_connector_update_edid_property(connector, NULL);
272 	return 0;
273 }
274 
275 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
276 {
277 	struct drm_bridge_connector *bridge_connector =
278 		to_drm_bridge_connector(connector);
279 	struct drm_bridge *bridge;
280 
281 	/*
282 	 * If display exposes EDID, then we parse that in the normal way to
283 	 * build table of supported modes.
284 	 */
285 	bridge = bridge_connector->bridge_edid;
286 	if (bridge)
287 		return drm_bridge_connector_get_modes_edid(connector, bridge);
288 
289 	/*
290 	 * Otherwise if the display pipeline reports modes (e.g. with a fixed
291 	 * resolution panel or an analog TV output), query it.
292 	 */
293 	bridge = bridge_connector->bridge_modes;
294 	if (bridge)
295 		return bridge->funcs->get_modes(bridge, connector);
296 
297 	/*
298 	 * We can't retrieve modes, which can happen for instance for a DVI or
299 	 * VGA output with the DDC bus unconnected. The KMS core will add the
300 	 * default modes.
301 	 */
302 	return 0;
303 }
304 
305 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
306 	.get_modes = drm_bridge_connector_get_modes,
307 	/* No need for .mode_valid(), the bridges are checked by the core. */
308 };
309 
310 /* -----------------------------------------------------------------------------
311  * Bridge Connector Initialisation
312  */
313 
314 /**
315  * drm_bridge_connector_init - Initialise a connector for a chain of bridges
316  * @drm: the DRM device
317  * @encoder: the encoder where the bridge chain starts
318  *
319  * Allocate, initialise and register a &drm_bridge_connector with the @drm
320  * device. The connector is associated with a chain of bridges that starts at
321  * the @encoder. All bridges in the chain shall report bridge operation flags
322  * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
323  * them may create a DRM connector directly.
324  *
325  * Returns a pointer to the new connector on success, or a negative error
326  * pointer otherwise.
327  */
328 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
329 						struct drm_encoder *encoder)
330 {
331 	struct drm_bridge_connector *bridge_connector;
332 	struct drm_connector *connector;
333 	struct i2c_adapter *ddc = NULL;
334 	struct drm_bridge *bridge;
335 	int connector_type;
336 
337 	bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
338 	if (!bridge_connector)
339 		return ERR_PTR(-ENOMEM);
340 
341 	bridge_connector->encoder = encoder;
342 
343 	/*
344 	 * TODO: Handle doublescan_allowed, stereo_allowed and
345 	 * ycbcr_420_allowed.
346 	 */
347 	connector = &bridge_connector->base;
348 	connector->interlace_allowed = true;
349 
350 	/*
351 	 * Initialise connector status handling. First locate the furthest
352 	 * bridges in the pipeline that support HPD and output detection. Then
353 	 * initialise the connector polling mode, using HPD if available and
354 	 * falling back to polling if supported. If neither HPD nor output
355 	 * detection are available, we don't support hotplug detection at all.
356 	 */
357 	connector_type = DRM_MODE_CONNECTOR_Unknown;
358 	drm_for_each_bridge_in_chain(encoder, bridge) {
359 		if (!bridge->interlace_allowed)
360 			connector->interlace_allowed = false;
361 
362 		if (bridge->ops & DRM_BRIDGE_OP_EDID)
363 			bridge_connector->bridge_edid = bridge;
364 		if (bridge->ops & DRM_BRIDGE_OP_HPD)
365 			bridge_connector->bridge_hpd = bridge;
366 		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
367 			bridge_connector->bridge_detect = bridge;
368 		if (bridge->ops & DRM_BRIDGE_OP_MODES)
369 			bridge_connector->bridge_modes = bridge;
370 
371 		if (!drm_bridge_get_next_bridge(bridge))
372 			connector_type = bridge->type;
373 
374 		if (bridge->ddc)
375 			ddc = bridge->ddc;
376 	}
377 
378 	if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
379 		kfree(bridge_connector);
380 		return ERR_PTR(-EINVAL);
381 	}
382 
383 	drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
384 				    connector_type, ddc);
385 	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
386 
387 	if (bridge_connector->bridge_hpd) {
388 		connector->polled = DRM_CONNECTOR_POLL_HPD;
389 		drm_bridge_connector_enable_hpd(connector);
390 	}
391 	else if (bridge_connector->bridge_detect)
392 		connector->polled = DRM_CONNECTOR_POLL_CONNECT
393 				  | DRM_CONNECTOR_POLL_DISCONNECT;
394 
395 	return connector;
396 }
397 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);
398