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 * struct &drm_bridge represents a device that hangs on to an encoder. These are
 35 * handy when a regular &drm_encoder entity isn't enough to represent the entire
 36 * encoder chain.
 37 *
 38 * A bridge is always attached 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 and hence are not visible to userspace. They
 53 * just provide additional hooks to get the desired output at the end of the
 54 * encoder chain.
 55 *
 56 * Bridges can also be chained up using the next pointer in struct &drm_bridge.
 57 *
 58 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges.
 59 */
 60
 61static DEFINE_MUTEX(bridge_lock);
 62static LIST_HEAD(bridge_list);
 63
 64/**
 65 * drm_bridge_add - add the given bridge to the global bridge list
 66 *
 67 * @bridge: bridge control structure
 68 *
 69 * RETURNS:
 70 * Unconditionally returns Zero.
 71 */
 72int drm_bridge_add(struct drm_bridge *bridge)
 73{
 74	mutex_lock(&bridge_lock);
 75	list_add_tail(&bridge->list, &bridge_list);
 76	mutex_unlock(&bridge_lock);
 77
 78	return 0;
 79}
 80EXPORT_SYMBOL(drm_bridge_add);
 81
 82/**
 83 * drm_bridge_remove - remove the given bridge from the global bridge list
 84 *
 85 * @bridge: bridge control structure
 86 */
 87void drm_bridge_remove(struct drm_bridge *bridge)
 88{
 89	mutex_lock(&bridge_lock);
 90	list_del_init(&bridge->list);
 91	mutex_unlock(&bridge_lock);
 92}
 93EXPORT_SYMBOL(drm_bridge_remove);
 94
 95/**
 96 * drm_bridge_attach - associate given bridge to our DRM device
 97 *
 98 * @dev: DRM device
 99 * @bridge: bridge control structure
100 *
101 * called by a kms driver to link one of our encoder/bridge to the given
102 * bridge.
103 *
104 * Note that setting up links between the bridge and our encoder/bridge
105 * objects needs to be handled by the kms driver itself
106 *
107 * RETURNS:
108 * Zero on success, error code on failure
109 */
110int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
111{
112	if (!dev || !bridge)
113		return -EINVAL;
114
115	if (bridge->dev)
116		return -EBUSY;
117
118	bridge->dev = dev;
119
120	if (bridge->funcs->attach)
121		return bridge->funcs->attach(bridge);
122
123	return 0;
124}
125EXPORT_SYMBOL(drm_bridge_attach);
126
127/**
128 * DOC: bridge callbacks
129 *
130 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
131 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
132 * These helpers call a specific &drm_bridge_funcs op for all the bridges
133 * during encoder configuration.
134 *
135 * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
136 */
137
138/**
139 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
140 *			   encoder chain
141 * @bridge: bridge control structure
142 * @mode: desired mode to be set for the bridge
143 * @adjusted_mode: updated mode that works for this bridge
144 *
145 * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the
146 * encoder chain, starting from the first bridge to the last.
147 *
148 * Note: the bridge passed should be the one closest to the encoder
149 *
150 * RETURNS:
151 * true on success, false on failure
152 */
153bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
154			const struct drm_display_mode *mode,
155			struct drm_display_mode *adjusted_mode)
156{
157	bool ret = true;
158
159	if (!bridge)
160		return true;
161
162	if (bridge->funcs->mode_fixup)
163		ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
164
165	ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
166
167	return ret;
168}
169EXPORT_SYMBOL(drm_bridge_mode_fixup);
170
171/**
172 * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all
173 *			bridges in the encoder chain.
174 * @bridge: bridge control structure
175 *
176 * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder
177 * chain, starting from the last bridge to the first. These are called before
178 * calling the encoder's prepare op.
179 *
180 * Note: the bridge passed should be the one closest to the encoder
181 */
182void drm_bridge_disable(struct drm_bridge *bridge)
183{
184	if (!bridge)
185		return;
186
187	drm_bridge_disable(bridge->next);
188
189	if (bridge->funcs->disable)
190		bridge->funcs->disable(bridge);
191}
192EXPORT_SYMBOL(drm_bridge_disable);
193
194/**
195 * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for
196 *			     all bridges in the encoder chain.
197 * @bridge: bridge control structure
198 *
199 * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the
200 * encoder chain, starting from the first bridge to the last. These are called
201 * after completing the encoder's prepare op.
202 *
203 * Note: the bridge passed should be the one closest to the encoder
204 */
205void drm_bridge_post_disable(struct drm_bridge *bridge)
206{
207	if (!bridge)
208		return;
209
210	if (bridge->funcs->post_disable)
211		bridge->funcs->post_disable(bridge);
212
213	drm_bridge_post_disable(bridge->next);
214}
215EXPORT_SYMBOL(drm_bridge_post_disable);
216
217/**
218 * drm_bridge_mode_set - set proposed mode for all bridges in the
219 *			 encoder chain
220 * @bridge: bridge control structure
221 * @mode: desired mode to be set for the bridge
222 * @adjusted_mode: updated mode that works for this bridge
223 *
224 * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the
225 * encoder chain, starting from the first bridge to the last.
226 *
227 * Note: the bridge passed should be the one closest to the encoder
228 */
229void drm_bridge_mode_set(struct drm_bridge *bridge,
230			struct drm_display_mode *mode,
231			struct drm_display_mode *adjusted_mode)
232{
233	if (!bridge)
234		return;
235
236	if (bridge->funcs->mode_set)
237		bridge->funcs->mode_set(bridge, mode, adjusted_mode);
238
239	drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
240}
241EXPORT_SYMBOL(drm_bridge_mode_set);
242
243/**
244 * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all
245 *			   bridges in the encoder chain.
246 * @bridge: bridge control structure
247 *
248 * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder
249 * chain, starting from the last bridge to the first. These are called
250 * before calling the encoder's commit op.
251 *
252 * Note: the bridge passed should be the one closest to the encoder
253 */
254void drm_bridge_pre_enable(struct drm_bridge *bridge)
255{
256	if (!bridge)
257		return;
258
259	drm_bridge_pre_enable(bridge->next);
260
261	if (bridge->funcs->pre_enable)
262		bridge->funcs->pre_enable(bridge);
263}
264EXPORT_SYMBOL(drm_bridge_pre_enable);
265
266/**
267 * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges
268 *		       in the encoder chain.
269 * @bridge: bridge control structure
270 *
271 * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder
272 * chain, starting from the first bridge to the last. These are called
273 * after completing the encoder's commit op.
274 *
275 * Note that the bridge passed should be the one closest to the encoder
276 */
277void drm_bridge_enable(struct drm_bridge *bridge)
278{
279	if (!bridge)
280		return;
281
282	if (bridge->funcs->enable)
283		bridge->funcs->enable(bridge);
284
285	drm_bridge_enable(bridge->next);
286}
287EXPORT_SYMBOL(drm_bridge_enable);
288
289#ifdef CONFIG_OF
290/**
291 * of_drm_find_bridge - find the bridge corresponding to the device node in
292 *			the global bridge list
293 *
294 * @np: device node
295 *
296 * RETURNS:
297 * drm_bridge control struct on success, NULL on failure
298 */
299struct drm_bridge *of_drm_find_bridge(struct device_node *np)
300{
301	struct drm_bridge *bridge;
302
303	mutex_lock(&bridge_lock);
304
305	list_for_each_entry(bridge, &bridge_list, list) {
306		if (bridge->of_node == np) {
307			mutex_unlock(&bridge_lock);
308			return bridge;
309		}
310	}
311
312	mutex_unlock(&bridge_lock);
313	return NULL;
314}
315EXPORT_SYMBOL(of_drm_find_bridge);
316#endif
317
318MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
319MODULE_DESCRIPTION("DRM bridge infrastructure");
320MODULE_LICENSE("GPL and additional rights");