1 /*
2 * Copyright (c) 2014 Samsung Electronics Co., Ltd
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sub license,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the
12 * next paragraph) shall be included in all copies or substantial portions
13 * of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 #include <linux/err.h>
25 #include <linux/module.h>
26
27 #include <drm/drm_crtc.h>
28
29 #include "drm/drmP.h"
30
31 /**
32 * DOC: overview
33 *
34 * drm_bridge represents a device that hangs on to an encoder. These are handy
35 * when a regular drm_encoder entity isn't enough to represent the entire
36 * encoder chain.
37 *
38 * A bridge is always associated to a single drm_encoder at a time, but can be
39 * either connected to it directly, or through an intermediate bridge:
40 *
41 * encoder ---> bridge B ---> bridge A
42 *
43 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to
44 * bridge A.
45 *
46 * The driver using the bridge is responsible to make the associations between
47 * the encoder and bridges. Once these links are made, the bridges will
48 * participate along with encoder functions to perform mode_set/enable/disable
49 * through the ops provided in drm_bridge_funcs.
50 *
51 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes,
52 * crtcs, encoders or connectors. They just provide additional hooks to get the
53 * desired output at the end of the encoder chain.
54 */
55
56 static DEFINE_MUTEX(bridge_lock);
57 static LIST_HEAD(bridge_list);
58
59 /**
60 * drm_bridge_add - add the given bridge to the global bridge list
61 *
62 * @bridge: bridge control structure
63 *
64 * RETURNS:
65 * Unconditionally returns Zero.
66 */
drm_bridge_add(struct drm_bridge * bridge)67 int drm_bridge_add(struct drm_bridge *bridge)
68 {
69 mutex_lock(&bridge_lock);
70 list_add_tail(&bridge->list, &bridge_list);
71 mutex_unlock(&bridge_lock);
72
73 return 0;
74 }
75 EXPORT_SYMBOL(drm_bridge_add);
76
77 /**
78 * drm_bridge_remove - remove the given bridge from the global bridge list
79 *
80 * @bridge: bridge control structure
81 */
drm_bridge_remove(struct drm_bridge * bridge)82 void drm_bridge_remove(struct drm_bridge *bridge)
83 {
84 mutex_lock(&bridge_lock);
85 list_del_init(&bridge->list);
86 mutex_unlock(&bridge_lock);
87 }
88 EXPORT_SYMBOL(drm_bridge_remove);
89
90 /**
91 * drm_bridge_attach - associate given bridge to our DRM device
92 *
93 * @dev: DRM device
94 * @bridge: bridge control structure
95 *
96 * called by a kms driver to link one of our encoder/bridge to the given
97 * bridge.
98 *
99 * Note that setting up links between the bridge and our encoder/bridge
100 * objects needs to be handled by the kms driver itself
101 *
102 * RETURNS:
103 * Zero on success, error code on failure
104 */
drm_bridge_attach(struct drm_device * dev,struct drm_bridge * bridge)105 int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
106 {
107 if (!dev || !bridge)
108 return -EINVAL;
109
110 if (bridge->dev)
111 return -EBUSY;
112
113 bridge->dev = dev;
114
115 if (bridge->funcs->attach)
116 return bridge->funcs->attach(bridge);
117
118 return 0;
119 }
120 EXPORT_SYMBOL(drm_bridge_attach);
121
122 /**
123 * DOC: bridge callbacks
124 *
125 * The drm_bridge_funcs ops are populated by the bridge driver. The drm
126 * internals(atomic and crtc helpers) use the helpers defined in drm_bridge.c
127 * These helpers call a specific drm_bridge_funcs op for all the bridges
128 * during encoder configuration.
129 *
130 * When creating a bridge driver, one can implement drm_bridge_funcs op with
131 * the help of these rough rules:
132 *
133 * pre_enable: this contains things needed to be done for the bridge before
134 * its clock and timings are enabled by its source. For a bridge, its source
135 * is generally the encoder or bridge just before it in the encoder chain.
136 *
137 * enable: this contains things needed to be done for the bridge once its
138 * source is enabled. In other words, enable is called once the source is
139 * ready with clock and timing needed by the bridge.
140 *
141 * disable: this contains things needed to be done for the bridge assuming
142 * that its source is still enabled, i.e. clock and timings are still on.
143 *
144 * post_disable: this contains things needed to be done for the bridge once
145 * its source is disabled, i.e. once clocks and timings are off.
146 *
147 * mode_fixup: this should fixup the given mode for the bridge. It is called
148 * after the encoder's mode fixup. mode_fixup can also reject a mode completely
149 * if it's unsuitable for the hardware.
150 *
151 * mode_set: this sets up the mode for the bridge. It assumes that its source
152 * (an encoder or a bridge) has set the mode too.
153 */
154
155 /**
156 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
157 * encoder chain
158 * @bridge: bridge control structure
159 * @mode: desired mode to be set for the bridge
160 * @adjusted_mode: updated mode that works for this bridge
161 *
162 * Calls 'mode_fixup' drm_bridge_funcs op for all the bridges in the
163 * encoder chain, starting from the first bridge to the last.
164 *
165 * Note: the bridge passed should be the one closest to the encoder
166 *
167 * RETURNS:
168 * true on success, false on failure
169 */
drm_bridge_mode_fixup(struct drm_bridge * bridge,const struct drm_display_mode * mode,struct drm_display_mode * adjusted_mode)170 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
171 const struct drm_display_mode *mode,
172 struct drm_display_mode *adjusted_mode)
173 {
174 bool ret = true;
175
176 if (!bridge)
177 return true;
178
179 if (bridge->funcs->mode_fixup)
180 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
181
182 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
183
184 return ret;
185 }
186 EXPORT_SYMBOL(drm_bridge_mode_fixup);
187
188 /**
189 * drm_bridge_disable - calls 'disable' drm_bridge_funcs op for all
190 * bridges in the encoder chain.
191 * @bridge: bridge control structure
192 *
193 * Calls 'disable' drm_bridge_funcs op for all the bridges in the encoder
194 * chain, starting from the last bridge to the first. These are called before
195 * calling the encoder's prepare op.
196 *
197 * Note: the bridge passed should be the one closest to the encoder
198 */
drm_bridge_disable(struct drm_bridge * bridge)199 void drm_bridge_disable(struct drm_bridge *bridge)
200 {
201 if (!bridge)
202 return;
203
204 drm_bridge_disable(bridge->next);
205
206 bridge->funcs->disable(bridge);
207 }
208 EXPORT_SYMBOL(drm_bridge_disable);
209
210 /**
211 * drm_bridge_post_disable - calls 'post_disable' drm_bridge_funcs op for
212 * all bridges in the encoder chain.
213 * @bridge: bridge control structure
214 *
215 * Calls 'post_disable' drm_bridge_funcs op for all the bridges in the
216 * encoder chain, starting from the first bridge to the last. These are called
217 * after completing the encoder's prepare op.
218 *
219 * Note: the bridge passed should be the one closest to the encoder
220 */
drm_bridge_post_disable(struct drm_bridge * bridge)221 void drm_bridge_post_disable(struct drm_bridge *bridge)
222 {
223 if (!bridge)
224 return;
225
226 bridge->funcs->post_disable(bridge);
227
228 drm_bridge_post_disable(bridge->next);
229 }
230 EXPORT_SYMBOL(drm_bridge_post_disable);
231
232 /**
233 * drm_bridge_mode_set - set proposed mode for all bridges in the
234 * encoder chain
235 * @bridge: bridge control structure
236 * @mode: desired mode to be set for the bridge
237 * @adjusted_mode: updated mode that works for this bridge
238 *
239 * Calls 'mode_set' drm_bridge_funcs op for all the bridges in the
240 * encoder chain, starting from the first bridge to the last.
241 *
242 * Note: the bridge passed should be the one closest to the encoder
243 */
drm_bridge_mode_set(struct drm_bridge * bridge,struct drm_display_mode * mode,struct drm_display_mode * adjusted_mode)244 void drm_bridge_mode_set(struct drm_bridge *bridge,
245 struct drm_display_mode *mode,
246 struct drm_display_mode *adjusted_mode)
247 {
248 if (!bridge)
249 return;
250
251 if (bridge->funcs->mode_set)
252 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
253
254 drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
255 }
256 EXPORT_SYMBOL(drm_bridge_mode_set);
257
258 /**
259 * drm_bridge_pre_enable - calls 'pre_enable' drm_bridge_funcs op for all
260 * bridges in the encoder chain.
261 * @bridge: bridge control structure
262 *
263 * Calls 'pre_enable' drm_bridge_funcs op for all the bridges in the encoder
264 * chain, starting from the last bridge to the first. These are called
265 * before calling the encoder's commit op.
266 *
267 * Note: the bridge passed should be the one closest to the encoder
268 */
drm_bridge_pre_enable(struct drm_bridge * bridge)269 void drm_bridge_pre_enable(struct drm_bridge *bridge)
270 {
271 if (!bridge)
272 return;
273
274 drm_bridge_pre_enable(bridge->next);
275
276 bridge->funcs->pre_enable(bridge);
277 }
278 EXPORT_SYMBOL(drm_bridge_pre_enable);
279
280 /**
281 * drm_bridge_enable - calls 'enable' drm_bridge_funcs op for all bridges
282 * in the encoder chain.
283 * @bridge: bridge control structure
284 *
285 * Calls 'enable' drm_bridge_funcs op for all the bridges in the encoder
286 * chain, starting from the first bridge to the last. These are called
287 * after completing the encoder's commit op.
288 *
289 * Note that the bridge passed should be the one closest to the encoder
290 */
drm_bridge_enable(struct drm_bridge * bridge)291 void drm_bridge_enable(struct drm_bridge *bridge)
292 {
293 if (!bridge)
294 return;
295
296 bridge->funcs->enable(bridge);
297
298 drm_bridge_enable(bridge->next);
299 }
300 EXPORT_SYMBOL(drm_bridge_enable);
301
302 #ifdef CONFIG_OF
303 /**
304 * of_drm_find_bridge - find the bridge corresponding to the device node in
305 * the global bridge list
306 *
307 * @np: device node
308 *
309 * RETURNS:
310 * drm_bridge control struct on success, NULL on failure
311 */
of_drm_find_bridge(struct device_node * np)312 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
313 {
314 struct drm_bridge *bridge;
315
316 mutex_lock(&bridge_lock);
317
318 list_for_each_entry(bridge, &bridge_list, list) {
319 if (bridge->of_node == np) {
320 mutex_unlock(&bridge_lock);
321 return bridge;
322 }
323 }
324
325 mutex_unlock(&bridge_lock);
326 return NULL;
327 }
328 EXPORT_SYMBOL(of_drm_find_bridge);
329 #endif
330
331 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
332 MODULE_DESCRIPTION("DRM bridge infrastructure");
333 MODULE_LICENSE("GPL and additional rights");
334