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#include <linux/mutex.h>
 27
 28#include <drm/drm_bridge.h>
 29#include <drm/drm_encoder.h>
 30
 31#include "drm_crtc_internal.h"
 32
 33/**
 34 * DOC: overview
 35 *
 36 * &struct drm_bridge represents a device that hangs on to an encoder. These are
 37 * handy when a regular &drm_encoder entity isn't enough to represent the entire
 38 * encoder chain.
 39 *
 40 * A bridge is always attached to a single &drm_encoder at a time, but can be
 41 * either connected to it directly, or through an intermediate bridge::
 42 *
 43 *     encoder ---> bridge B ---> bridge A
 44 *
 45 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to
 46 * bridge A.
 47 *
 48 * The driver using the bridge is responsible to make the associations between
 49 * the encoder and bridges. Once these links are made, the bridges will
 50 * participate along with encoder functions to perform mode_set/enable/disable
 51 * through the ops provided in &drm_bridge_funcs.
 52 *
 53 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes,
 54 * CRTCs, encoders or connectors and hence are not visible to userspace. They
 55 * just provide additional hooks to get the desired output at the end of the
 56 * encoder chain.
 57 *
 58 * Bridges can also be chained up using the &drm_bridge.next pointer.
 59 *
 60 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges.
 61 */
 62
 63static DEFINE_MUTEX(bridge_lock);
 64static LIST_HEAD(bridge_list);
 65
 66/**
 67 * drm_bridge_add - add the given bridge to the global bridge list
 68 *
 69 * @bridge: bridge control structure
 70 */
 71void drm_bridge_add(struct drm_bridge *bridge)
 72{
 73	mutex_lock(&bridge_lock);
 74	list_add_tail(&bridge->list, &bridge_list);
 75	mutex_unlock(&bridge_lock);
 76}
 77EXPORT_SYMBOL(drm_bridge_add);
 78
 79/**
 80 * drm_bridge_remove - remove the given bridge from the global bridge list
 81 *
 82 * @bridge: bridge control structure
 83 */
 84void drm_bridge_remove(struct drm_bridge *bridge)
 85{
 86	mutex_lock(&bridge_lock);
 87	list_del_init(&bridge->list);
 88	mutex_unlock(&bridge_lock);
 89}
 90EXPORT_SYMBOL(drm_bridge_remove);
 91
 92/**
 93 * drm_bridge_attach - attach the bridge to an encoder's chain
 94 *
 95 * @encoder: DRM encoder
 96 * @bridge: bridge to attach
 97 * @previous: previous bridge in the chain (optional)
 98 *
 99 * Called by a kms driver to link the bridge to an encoder's chain. The previous
100 * argument specifies the previous bridge in the chain. If NULL, the bridge is
101 * linked directly at the encoder's output. Otherwise it is linked at the
102 * previous bridge's output.
103 *
104 * If non-NULL the previous bridge must be already attached by a call to this
105 * function.
106 *
107 * RETURNS:
108 * Zero on success, error code on failure
109 */
110int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
111		      struct drm_bridge *previous)
112{
113	int ret;
114
115	if (!encoder || !bridge)
116		return -EINVAL;
117
118	if (previous && (!previous->dev || previous->encoder != encoder))
119		return -EINVAL;
120
121	if (bridge->dev)
122		return -EBUSY;
123
124	bridge->dev = encoder->dev;
125	bridge->encoder = encoder;
126
127	if (bridge->funcs->attach) {
128		ret = bridge->funcs->attach(bridge);
129		if (ret < 0) {
130			bridge->dev = NULL;
131			bridge->encoder = NULL;
132			return ret;
133		}
134	}
135
136	if (previous)
137		previous->next = bridge;
138	else
139		encoder->bridge = bridge;
140
141	return 0;
142}
143EXPORT_SYMBOL(drm_bridge_attach);
144
145void drm_bridge_detach(struct drm_bridge *bridge)
146{
147	if (WARN_ON(!bridge))
148		return;
149
150	if (WARN_ON(!bridge->dev))
151		return;
152
153	if (bridge->funcs->detach)
154		bridge->funcs->detach(bridge);
155
156	bridge->dev = NULL;
157}
158
159/**
160 * DOC: bridge callbacks
161 *
162 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
163 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
164 * These helpers call a specific &drm_bridge_funcs op for all the bridges
165 * during encoder configuration.
166 *
167 * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
168 */
169
170/**
171 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
172 *			   encoder chain
173 * @bridge: bridge control structure
174 * @mode: desired mode to be set for the bridge
175 * @adjusted_mode: updated mode that works for this bridge
176 *
177 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
178 * encoder chain, starting from the first bridge to the last.
179 *
180 * Note: the bridge passed should be the one closest to the encoder
181 *
182 * RETURNS:
183 * true on success, false on failure
184 */
185bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
186			const struct drm_display_mode *mode,
187			struct drm_display_mode *adjusted_mode)
188{
189	bool ret = true;
190
191	if (!bridge)
192		return true;
193
194	if (bridge->funcs->mode_fixup)
195		ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
196
197	ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
198
199	return ret;
200}
201EXPORT_SYMBOL(drm_bridge_mode_fixup);
202
203/**
204 * drm_bridge_mode_valid - validate the mode against all bridges in the
205 * 			   encoder chain.
206 * @bridge: bridge control structure
207 * @mode: desired mode to be validated
208 *
209 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
210 * chain, starting from the first bridge to the last. If at least one bridge
211 * does not accept the mode the function returns the error code.
212 *
213 * Note: the bridge passed should be the one closest to the encoder.
214 *
215 * RETURNS:
216 * MODE_OK on success, drm_mode_status Enum error code on failure
217 */
218enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
219					   const struct drm_display_mode *mode)
220{
221	enum drm_mode_status ret = MODE_OK;
222
223	if (!bridge)
224		return ret;
225
226	if (bridge->funcs->mode_valid)
227		ret = bridge->funcs->mode_valid(bridge, mode);
228
229	if (ret != MODE_OK)
230		return ret;
231
232	return drm_bridge_mode_valid(bridge->next, mode);
233}
234EXPORT_SYMBOL(drm_bridge_mode_valid);
235
236/**
237 * drm_bridge_disable - disables all bridges in the encoder chain
238 * @bridge: bridge control structure
239 *
240 * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
241 * chain, starting from the last bridge to the first. These are called before
242 * calling the encoder's prepare op.
243 *
244 * Note: the bridge passed should be the one closest to the encoder
245 */
246void drm_bridge_disable(struct drm_bridge *bridge)
247{
248	if (!bridge)
249		return;
250
251	drm_bridge_disable(bridge->next);
252
253	if (bridge->funcs->disable)
254		bridge->funcs->disable(bridge);
255}
256EXPORT_SYMBOL(drm_bridge_disable);
257
258/**
259 * drm_bridge_post_disable - cleans up after disabling all bridges in the encoder chain
260 * @bridge: bridge control structure
261 *
262 * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
263 * encoder chain, starting from the first bridge to the last. These are called
264 * after completing the encoder's prepare op.
265 *
266 * Note: the bridge passed should be the one closest to the encoder
267 */
268void drm_bridge_post_disable(struct drm_bridge *bridge)
269{
270	if (!bridge)
271		return;
272
273	if (bridge->funcs->post_disable)
274		bridge->funcs->post_disable(bridge);
275
276	drm_bridge_post_disable(bridge->next);
277}
278EXPORT_SYMBOL(drm_bridge_post_disable);
279
280/**
281 * drm_bridge_mode_set - set proposed mode for all bridges in the
282 *			 encoder chain
283 * @bridge: bridge control structure
284 * @mode: desired mode to be set for the bridge
285 * @adjusted_mode: updated mode that works for this bridge
286 *
287 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
288 * encoder chain, starting from the first bridge to the last.
289 *
290 * Note: the bridge passed should be the one closest to the encoder
291 */
292void drm_bridge_mode_set(struct drm_bridge *bridge,
293			struct drm_display_mode *mode,
294			struct drm_display_mode *adjusted_mode)
295{
296	if (!bridge)
297		return;
298
299	if (bridge->funcs->mode_set)
300		bridge->funcs->mode_set(bridge, mode, adjusted_mode);
301
302	drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
303}
304EXPORT_SYMBOL(drm_bridge_mode_set);
305
306/**
307 * drm_bridge_pre_enable - prepares for enabling all
308 *			   bridges in the encoder chain
309 * @bridge: bridge control structure
310 *
311 * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
312 * chain, starting from the last bridge to the first. These are called
313 * before calling the encoder's commit op.
314 *
315 * Note: the bridge passed should be the one closest to the encoder
316 */
317void drm_bridge_pre_enable(struct drm_bridge *bridge)
318{
319	if (!bridge)
320		return;
321
322	drm_bridge_pre_enable(bridge->next);
323
324	if (bridge->funcs->pre_enable)
325		bridge->funcs->pre_enable(bridge);
326}
327EXPORT_SYMBOL(drm_bridge_pre_enable);
328
329/**
330 * drm_bridge_enable - enables all bridges in the encoder chain
331 * @bridge: bridge control structure
332 *
333 * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
334 * chain, starting from the first bridge to the last. These are called
335 * after completing the encoder's commit op.
336 *
337 * Note that the bridge passed should be the one closest to the encoder
338 */
339void drm_bridge_enable(struct drm_bridge *bridge)
340{
341	if (!bridge)
342		return;
343
344	if (bridge->funcs->enable)
345		bridge->funcs->enable(bridge);
346
347	drm_bridge_enable(bridge->next);
348}
349EXPORT_SYMBOL(drm_bridge_enable);
350
351#ifdef CONFIG_OF
352/**
353 * of_drm_find_bridge - find the bridge corresponding to the device node in
354 *			the global bridge list
355 *
356 * @np: device node
357 *
358 * RETURNS:
359 * drm_bridge control struct on success, NULL on failure
360 */
361struct drm_bridge *of_drm_find_bridge(struct device_node *np)
362{
363	struct drm_bridge *bridge;
364
365	mutex_lock(&bridge_lock);
366
367	list_for_each_entry(bridge, &bridge_list, list) {
368		if (bridge->of_node == np) {
369			mutex_unlock(&bridge_lock);
370			return bridge;
371		}
372	}
373
374	mutex_unlock(&bridge_lock);
375	return NULL;
376}
377EXPORT_SYMBOL(of_drm_find_bridge);
378#endif
379
380MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
381MODULE_DESCRIPTION("DRM bridge infrastructure");
382MODULE_LICENSE("GPL and additional rights");