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_connector_hotplug_event(connector);
129 }
130 
131 static void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
132 {
133 	struct drm_bridge_connector *bridge_connector =
134 		to_drm_bridge_connector(connector);
135 	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
136 
137 	if (hpd)
138 		drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
139 				      bridge_connector);
140 }
141 
142 static void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
143 {
144 	struct drm_bridge_connector *bridge_connector =
145 		to_drm_bridge_connector(connector);
146 	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
147 
148 	if (hpd)
149 		drm_bridge_hpd_disable(hpd);
150 }
151 
152 /* -----------------------------------------------------------------------------
153  * Bridge Connector Functions
154  */
155 
156 static enum drm_connector_status
157 drm_bridge_connector_detect(struct drm_connector *connector, bool force)
158 {
159 	struct drm_bridge_connector *bridge_connector =
160 		to_drm_bridge_connector(connector);
161 	struct drm_bridge *detect = bridge_connector->bridge_detect;
162 	enum drm_connector_status status;
163 
164 	if (detect) {
165 		status = detect->funcs->detect(detect);
166 
167 		drm_bridge_connector_hpd_notify(connector, status);
168 	} else {
169 		switch (connector->connector_type) {
170 		case DRM_MODE_CONNECTOR_DPI:
171 		case DRM_MODE_CONNECTOR_LVDS:
172 		case DRM_MODE_CONNECTOR_DSI:
173 		case DRM_MODE_CONNECTOR_eDP:
174 			status = connector_status_connected;
175 			break;
176 		default:
177 			status = connector_status_unknown;
178 			break;
179 		}
180 	}
181 
182 	return status;
183 }
184 
185 static void drm_bridge_connector_destroy(struct drm_connector *connector)
186 {
187 	struct drm_bridge_connector *bridge_connector =
188 		to_drm_bridge_connector(connector);
189 
190 	if (bridge_connector->bridge_hpd) {
191 		struct drm_bridge *hpd = bridge_connector->bridge_hpd;
192 
193 		drm_bridge_hpd_disable(hpd);
194 	}
195 
196 	drm_connector_unregister(connector);
197 	drm_connector_cleanup(connector);
198 
199 	kfree(bridge_connector);
200 }
201 
202 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
203 					      struct dentry *root)
204 {
205 	struct drm_bridge_connector *bridge_connector =
206 		to_drm_bridge_connector(connector);
207 	struct drm_encoder *encoder = bridge_connector->encoder;
208 	struct drm_bridge *bridge;
209 
210 	list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
211 		if (bridge->funcs->debugfs_init)
212 			bridge->funcs->debugfs_init(bridge, root);
213 	}
214 }
215 
216 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
217 	.reset = drm_atomic_helper_connector_reset,
218 	.detect = drm_bridge_connector_detect,
219 	.fill_modes = drm_helper_probe_single_connector_modes,
220 	.destroy = drm_bridge_connector_destroy,
221 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
222 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
223 	.debugfs_init = drm_bridge_connector_debugfs_init,
224 };
225 
226 /* -----------------------------------------------------------------------------
227  * Bridge Connector Helper Functions
228  */
229 
230 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
231 					       struct drm_bridge *bridge)
232 {
233 	enum drm_connector_status status;
234 	struct edid *edid;
235 	int n;
236 
237 	status = drm_bridge_connector_detect(connector, false);
238 	if (status != connector_status_connected)
239 		goto no_edid;
240 
241 	edid = bridge->funcs->get_edid(bridge, connector);
242 	if (!drm_edid_is_valid(edid)) {
243 		kfree(edid);
244 		goto no_edid;
245 	}
246 
247 	drm_connector_update_edid_property(connector, edid);
248 	n = drm_add_edid_modes(connector, edid);
249 
250 	kfree(edid);
251 	return n;
252 
253 no_edid:
254 	drm_connector_update_edid_property(connector, NULL);
255 	return 0;
256 }
257 
258 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
259 {
260 	struct drm_bridge_connector *bridge_connector =
261 		to_drm_bridge_connector(connector);
262 	struct drm_bridge *bridge;
263 
264 	/*
265 	 * If display exposes EDID, then we parse that in the normal way to
266 	 * build table of supported modes.
267 	 */
268 	bridge = bridge_connector->bridge_edid;
269 	if (bridge)
270 		return drm_bridge_connector_get_modes_edid(connector, bridge);
271 
272 	/*
273 	 * Otherwise if the display pipeline reports modes (e.g. with a fixed
274 	 * resolution panel or an analog TV output), query it.
275 	 */
276 	bridge = bridge_connector->bridge_modes;
277 	if (bridge)
278 		return bridge->funcs->get_modes(bridge, connector);
279 
280 	/*
281 	 * We can't retrieve modes, which can happen for instance for a DVI or
282 	 * VGA output with the DDC bus unconnected. The KMS core will add the
283 	 * default modes.
284 	 */
285 	return 0;
286 }
287 
288 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
289 	.get_modes = drm_bridge_connector_get_modes,
290 	/* No need for .mode_valid(), the bridges are checked by the core. */
291 	.enable_hpd = drm_bridge_connector_enable_hpd,
292 	.disable_hpd = drm_bridge_connector_disable_hpd,
293 };
294 
295 /* -----------------------------------------------------------------------------
296  * Bridge Connector Initialisation
297  */
298 
299 /**
300  * drm_bridge_connector_init - Initialise a connector for a chain of bridges
301  * @drm: the DRM device
302  * @encoder: the encoder where the bridge chain starts
303  *
304  * Allocate, initialise and register a &drm_bridge_connector with the @drm
305  * device. The connector is associated with a chain of bridges that starts at
306  * the @encoder. All bridges in the chain shall report bridge operation flags
307  * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
308  * them may create a DRM connector directly.
309  *
310  * Returns a pointer to the new connector on success, or a negative error
311  * pointer otherwise.
312  */
313 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
314 						struct drm_encoder *encoder)
315 {
316 	struct drm_bridge_connector *bridge_connector;
317 	struct drm_connector *connector;
318 	struct i2c_adapter *ddc = NULL;
319 	struct drm_bridge *bridge, *panel_bridge = NULL;
320 	int connector_type;
321 	int ret;
322 
323 	bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
324 	if (!bridge_connector)
325 		return ERR_PTR(-ENOMEM);
326 
327 	bridge_connector->encoder = encoder;
328 
329 	/*
330 	 * TODO: Handle doublescan_allowed, stereo_allowed and
331 	 * ycbcr_420_allowed.
332 	 */
333 	connector = &bridge_connector->base;
334 	connector->interlace_allowed = true;
335 
336 	/*
337 	 * Initialise connector status handling. First locate the furthest
338 	 * bridges in the pipeline that support HPD and output detection. Then
339 	 * initialise the connector polling mode, using HPD if available and
340 	 * falling back to polling if supported. If neither HPD nor output
341 	 * detection are available, we don't support hotplug detection at all.
342 	 */
343 	connector_type = DRM_MODE_CONNECTOR_Unknown;
344 	drm_for_each_bridge_in_chain(encoder, bridge) {
345 		if (!bridge->interlace_allowed)
346 			connector->interlace_allowed = false;
347 
348 		if (bridge->ops & DRM_BRIDGE_OP_EDID)
349 			bridge_connector->bridge_edid = bridge;
350 		if (bridge->ops & DRM_BRIDGE_OP_HPD)
351 			bridge_connector->bridge_hpd = bridge;
352 		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
353 			bridge_connector->bridge_detect = bridge;
354 		if (bridge->ops & DRM_BRIDGE_OP_MODES)
355 			bridge_connector->bridge_modes = bridge;
356 
357 		if (!drm_bridge_get_next_bridge(bridge))
358 			connector_type = bridge->type;
359 
360 		if (bridge->ddc)
361 			ddc = bridge->ddc;
362 
363 		if (drm_bridge_is_panel(bridge))
364 			panel_bridge = bridge;
365 	}
366 
367 	if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
368 		kfree(bridge_connector);
369 		return ERR_PTR(-EINVAL);
370 	}
371 
372 	ret = drm_connector_init_with_ddc(drm, connector,
373 					  &drm_bridge_connector_funcs,
374 					  connector_type, ddc);
375 	if (ret) {
376 		kfree(bridge_connector);
377 		return ERR_PTR(ret);
378 	}
379 
380 	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
381 
382 	if (bridge_connector->bridge_hpd)
383 		connector->polled = DRM_CONNECTOR_POLL_HPD;
384 	else if (bridge_connector->bridge_detect)
385 		connector->polled = DRM_CONNECTOR_POLL_CONNECT
386 				  | DRM_CONNECTOR_POLL_DISCONNECT;
387 
388 	if (panel_bridge)
389 		drm_panel_bridge_set_orientation(connector, panel_bridge);
390 
391 	return connector;
392 }
393 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);
394