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1/*
2 * Copyright (C) 2013, NVIDIA Corporation. All rights reserved.
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/backlight.h>
25#include <linux/err.h>
26#include <linux/module.h>
27
28#include <drm/drm_crtc.h>
29#include <drm/drm_panel.h>
30#include <drm/drm_print.h>
31
32static DEFINE_MUTEX(panel_lock);
33static LIST_HEAD(panel_list);
34
35/**
36 * DOC: drm panel
37 *
38 * The DRM panel helpers allow drivers to register panel objects with a
39 * central registry and provide functions to retrieve those panels in display
40 * drivers.
41 *
42 * For easy integration into drivers using the &drm_bridge infrastructure please
43 * take look at drm_panel_bridge_add() and devm_drm_panel_bridge_add().
44 */
45
46/**
47 * drm_panel_init - initialize a panel
48 * @panel: DRM panel
49 * @dev: parent device of the panel
50 * @funcs: panel operations
51 * @connector_type: the connector type (DRM_MODE_CONNECTOR_*) corresponding to
52 * the panel interface
53 *
54 * Initialize the panel structure for subsequent registration with
55 * drm_panel_add().
56 */
57void drm_panel_init(struct drm_panel *panel, struct device *dev,
58 const struct drm_panel_funcs *funcs, int connector_type)
59{
60 INIT_LIST_HEAD(&panel->list);
61 INIT_LIST_HEAD(&panel->followers);
62 mutex_init(&panel->follower_lock);
63 panel->dev = dev;
64 panel->funcs = funcs;
65 panel->connector_type = connector_type;
66}
67EXPORT_SYMBOL(drm_panel_init);
68
69/**
70 * drm_panel_add - add a panel to the global registry
71 * @panel: panel to add
72 *
73 * Add a panel to the global registry so that it can be looked up by display
74 * drivers.
75 */
76void drm_panel_add(struct drm_panel *panel)
77{
78 mutex_lock(&panel_lock);
79 list_add_tail(&panel->list, &panel_list);
80 mutex_unlock(&panel_lock);
81}
82EXPORT_SYMBOL(drm_panel_add);
83
84/**
85 * drm_panel_remove - remove a panel from the global registry
86 * @panel: DRM panel
87 *
88 * Removes a panel from the global registry.
89 */
90void drm_panel_remove(struct drm_panel *panel)
91{
92 mutex_lock(&panel_lock);
93 list_del_init(&panel->list);
94 mutex_unlock(&panel_lock);
95}
96EXPORT_SYMBOL(drm_panel_remove);
97
98/**
99 * drm_panel_prepare - power on a panel
100 * @panel: DRM panel
101 *
102 * Calling this function will enable power and deassert any reset signals to
103 * the panel. After this has completed it is possible to communicate with any
104 * integrated circuitry via a command bus.
105 *
106 * Return: 0 on success or a negative error code on failure.
107 */
108int drm_panel_prepare(struct drm_panel *panel)
109{
110 struct drm_panel_follower *follower;
111 int ret;
112
113 if (!panel)
114 return -EINVAL;
115
116 if (panel->prepared) {
117 dev_warn(panel->dev, "Skipping prepare of already prepared panel\n");
118 return 0;
119 }
120
121 mutex_lock(&panel->follower_lock);
122
123 if (panel->funcs && panel->funcs->prepare) {
124 ret = panel->funcs->prepare(panel);
125 if (ret < 0)
126 goto exit;
127 }
128 panel->prepared = true;
129
130 list_for_each_entry(follower, &panel->followers, list) {
131 ret = follower->funcs->panel_prepared(follower);
132 if (ret < 0)
133 dev_info(panel->dev, "%ps failed: %d\n",
134 follower->funcs->panel_prepared, ret);
135 }
136
137 ret = 0;
138exit:
139 mutex_unlock(&panel->follower_lock);
140
141 return ret;
142}
143EXPORT_SYMBOL(drm_panel_prepare);
144
145/**
146 * drm_panel_unprepare - power off a panel
147 * @panel: DRM panel
148 *
149 * Calling this function will completely power off a panel (assert the panel's
150 * reset, turn off power supplies, ...). After this function has completed, it
151 * is usually no longer possible to communicate with the panel until another
152 * call to drm_panel_prepare().
153 *
154 * Return: 0 on success or a negative error code on failure.
155 */
156int drm_panel_unprepare(struct drm_panel *panel)
157{
158 struct drm_panel_follower *follower;
159 int ret;
160
161 if (!panel)
162 return -EINVAL;
163
164 /*
165 * If you are seeing the warning below it likely means one of two things:
166 * - Your panel driver incorrectly calls drm_panel_unprepare() in its
167 * shutdown routine. You should delete this.
168 * - You are using panel-edp or panel-simple and your DRM modeset
169 * driver's shutdown() callback happened after the panel's shutdown().
170 * In this case the warning is harmless though ideally you should
171 * figure out how to reverse the order of the shutdown() callbacks.
172 */
173 if (!panel->prepared) {
174 dev_warn(panel->dev, "Skipping unprepare of already unprepared panel\n");
175 return 0;
176 }
177
178 mutex_lock(&panel->follower_lock);
179
180 list_for_each_entry(follower, &panel->followers, list) {
181 ret = follower->funcs->panel_unpreparing(follower);
182 if (ret < 0)
183 dev_info(panel->dev, "%ps failed: %d\n",
184 follower->funcs->panel_unpreparing, ret);
185 }
186
187 if (panel->funcs && panel->funcs->unprepare) {
188 ret = panel->funcs->unprepare(panel);
189 if (ret < 0)
190 goto exit;
191 }
192 panel->prepared = false;
193
194 ret = 0;
195exit:
196 mutex_unlock(&panel->follower_lock);
197
198 return ret;
199}
200EXPORT_SYMBOL(drm_panel_unprepare);
201
202/**
203 * drm_panel_enable - enable a panel
204 * @panel: DRM panel
205 *
206 * Calling this function will cause the panel display drivers to be turned on
207 * and the backlight to be enabled. Content will be visible on screen after
208 * this call completes.
209 *
210 * Return: 0 on success or a negative error code on failure.
211 */
212int drm_panel_enable(struct drm_panel *panel)
213{
214 int ret;
215
216 if (!panel)
217 return -EINVAL;
218
219 if (panel->enabled) {
220 dev_warn(panel->dev, "Skipping enable of already enabled panel\n");
221 return 0;
222 }
223
224 if (panel->funcs && panel->funcs->enable) {
225 ret = panel->funcs->enable(panel);
226 if (ret < 0)
227 return ret;
228 }
229 panel->enabled = true;
230
231 ret = backlight_enable(panel->backlight);
232 if (ret < 0)
233 DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n",
234 ret);
235
236 return 0;
237}
238EXPORT_SYMBOL(drm_panel_enable);
239
240/**
241 * drm_panel_disable - disable a panel
242 * @panel: DRM panel
243 *
244 * This will typically turn off the panel's backlight or disable the display
245 * drivers. For smart panels it should still be possible to communicate with
246 * the integrated circuitry via any command bus after this call.
247 *
248 * Return: 0 on success or a negative error code on failure.
249 */
250int drm_panel_disable(struct drm_panel *panel)
251{
252 int ret;
253
254 if (!panel)
255 return -EINVAL;
256
257 /*
258 * If you are seeing the warning below it likely means one of two things:
259 * - Your panel driver incorrectly calls drm_panel_disable() in its
260 * shutdown routine. You should delete this.
261 * - You are using panel-edp or panel-simple and your DRM modeset
262 * driver's shutdown() callback happened after the panel's shutdown().
263 * In this case the warning is harmless though ideally you should
264 * figure out how to reverse the order of the shutdown() callbacks.
265 */
266 if (!panel->enabled) {
267 dev_warn(panel->dev, "Skipping disable of already disabled panel\n");
268 return 0;
269 }
270
271 ret = backlight_disable(panel->backlight);
272 if (ret < 0)
273 DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n",
274 ret);
275
276 if (panel->funcs && panel->funcs->disable) {
277 ret = panel->funcs->disable(panel);
278 if (ret < 0)
279 return ret;
280 }
281 panel->enabled = false;
282
283 return 0;
284}
285EXPORT_SYMBOL(drm_panel_disable);
286
287/**
288 * drm_panel_get_modes - probe the available display modes of a panel
289 * @panel: DRM panel
290 * @connector: DRM connector
291 *
292 * The modes probed from the panel are automatically added to the connector
293 * that the panel is attached to.
294 *
295 * Return: The number of modes available from the panel on success, or 0 on
296 * failure (no modes).
297 */
298int drm_panel_get_modes(struct drm_panel *panel,
299 struct drm_connector *connector)
300{
301 if (!panel)
302 return 0;
303
304 if (panel->funcs && panel->funcs->get_modes) {
305 int num;
306
307 num = panel->funcs->get_modes(panel, connector);
308 if (num > 0)
309 return num;
310 }
311
312 return 0;
313}
314EXPORT_SYMBOL(drm_panel_get_modes);
315
316#ifdef CONFIG_OF
317/**
318 * of_drm_find_panel - look up a panel using a device tree node
319 * @np: device tree node of the panel
320 *
321 * Searches the set of registered panels for one that matches the given device
322 * tree node. If a matching panel is found, return a pointer to it.
323 *
324 * Return: A pointer to the panel registered for the specified device tree
325 * node or an ERR_PTR() if no panel matching the device tree node can be found.
326 *
327 * Possible error codes returned by this function:
328 *
329 * - EPROBE_DEFER: the panel device has not been probed yet, and the caller
330 * should retry later
331 * - ENODEV: the device is not available (status != "okay" or "ok")
332 */
333struct drm_panel *of_drm_find_panel(const struct device_node *np)
334{
335 struct drm_panel *panel;
336
337 if (!of_device_is_available(np))
338 return ERR_PTR(-ENODEV);
339
340 mutex_lock(&panel_lock);
341
342 list_for_each_entry(panel, &panel_list, list) {
343 if (panel->dev->of_node == np) {
344 mutex_unlock(&panel_lock);
345 return panel;
346 }
347 }
348
349 mutex_unlock(&panel_lock);
350 return ERR_PTR(-EPROBE_DEFER);
351}
352EXPORT_SYMBOL(of_drm_find_panel);
353
354/**
355 * of_drm_get_panel_orientation - look up the orientation of the panel through
356 * the "rotation" binding from a device tree node
357 * @np: device tree node of the panel
358 * @orientation: orientation enum to be filled in
359 *
360 * Looks up the rotation of a panel in the device tree. The orientation of the
361 * panel is expressed as a property name "rotation" in the device tree. The
362 * rotation in the device tree is counter clockwise.
363 *
364 * Return: 0 when a valid rotation value (0, 90, 180, or 270) is read or the
365 * rotation property doesn't exist. Return a negative error code on failure.
366 */
367int of_drm_get_panel_orientation(const struct device_node *np,
368 enum drm_panel_orientation *orientation)
369{
370 int rotation, ret;
371
372 ret = of_property_read_u32(np, "rotation", &rotation);
373 if (ret == -EINVAL) {
374 /* Don't return an error if there's no rotation property. */
375 *orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
376 return 0;
377 }
378
379 if (ret < 0)
380 return ret;
381
382 if (rotation == 0)
383 *orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
384 else if (rotation == 90)
385 *orientation = DRM_MODE_PANEL_ORIENTATION_RIGHT_UP;
386 else if (rotation == 180)
387 *orientation = DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
388 else if (rotation == 270)
389 *orientation = DRM_MODE_PANEL_ORIENTATION_LEFT_UP;
390 else
391 return -EINVAL;
392
393 return 0;
394}
395EXPORT_SYMBOL(of_drm_get_panel_orientation);
396#endif
397
398/**
399 * drm_is_panel_follower() - Check if the device is a panel follower
400 * @dev: The 'struct device' to check
401 *
402 * This checks to see if a device needs to be power sequenced together with
403 * a panel using the panel follower API.
404 * At the moment panels can only be followed on device tree enabled systems.
405 * The "panel" property of the follower points to the panel to be followed.
406 *
407 * Return: true if we should be power sequenced with a panel; false otherwise.
408 */
409bool drm_is_panel_follower(struct device *dev)
410{
411 /*
412 * The "panel" property is actually a phandle, but for simplicity we
413 * don't bother trying to parse it here. We just need to know if the
414 * property is there.
415 */
416 return of_property_read_bool(dev->of_node, "panel");
417}
418EXPORT_SYMBOL(drm_is_panel_follower);
419
420/**
421 * drm_panel_add_follower() - Register something to follow panel state.
422 * @follower_dev: The 'struct device' for the follower.
423 * @follower: The panel follower descriptor for the follower.
424 *
425 * A panel follower is called right after preparing the panel and right before
426 * unpreparing the panel. It's primary intention is to power on an associated
427 * touchscreen, though it could be used for any similar devices. Multiple
428 * devices are allowed the follow the same panel.
429 *
430 * If a follower is added to a panel that's already been turned on, the
431 * follower's prepare callback is called right away.
432 *
433 * At the moment panels can only be followed on device tree enabled systems.
434 * The "panel" property of the follower points to the panel to be followed.
435 *
436 * Return: 0 or an error code. Note that -ENODEV means that we detected that
437 * follower_dev is not actually following a panel. The caller may
438 * choose to ignore this return value if following a panel is optional.
439 */
440int drm_panel_add_follower(struct device *follower_dev,
441 struct drm_panel_follower *follower)
442{
443 struct device_node *panel_np;
444 struct drm_panel *panel;
445 int ret;
446
447 panel_np = of_parse_phandle(follower_dev->of_node, "panel", 0);
448 if (!panel_np)
449 return -ENODEV;
450
451 panel = of_drm_find_panel(panel_np);
452 of_node_put(panel_np);
453 if (IS_ERR(panel))
454 return PTR_ERR(panel);
455
456 get_device(panel->dev);
457 follower->panel = panel;
458
459 mutex_lock(&panel->follower_lock);
460
461 list_add_tail(&follower->list, &panel->followers);
462 if (panel->prepared) {
463 ret = follower->funcs->panel_prepared(follower);
464 if (ret < 0)
465 dev_info(panel->dev, "%ps failed: %d\n",
466 follower->funcs->panel_prepared, ret);
467 }
468
469 mutex_unlock(&panel->follower_lock);
470
471 return 0;
472}
473EXPORT_SYMBOL(drm_panel_add_follower);
474
475/**
476 * drm_panel_remove_follower() - Reverse drm_panel_add_follower().
477 * @follower: The panel follower descriptor for the follower.
478 *
479 * Undo drm_panel_add_follower(). This includes calling the follower's
480 * unprepare function if we're removed from a panel that's currently prepared.
481 *
482 * Return: 0 or an error code.
483 */
484void drm_panel_remove_follower(struct drm_panel_follower *follower)
485{
486 struct drm_panel *panel = follower->panel;
487 int ret;
488
489 mutex_lock(&panel->follower_lock);
490
491 if (panel->prepared) {
492 ret = follower->funcs->panel_unpreparing(follower);
493 if (ret < 0)
494 dev_info(panel->dev, "%ps failed: %d\n",
495 follower->funcs->panel_unpreparing, ret);
496 }
497 list_del_init(&follower->list);
498
499 mutex_unlock(&panel->follower_lock);
500
501 put_device(panel->dev);
502}
503EXPORT_SYMBOL(drm_panel_remove_follower);
504
505static void drm_panel_remove_follower_void(void *follower)
506{
507 drm_panel_remove_follower(follower);
508}
509
510/**
511 * devm_drm_panel_add_follower() - devm version of drm_panel_add_follower()
512 * @follower_dev: The 'struct device' for the follower.
513 * @follower: The panel follower descriptor for the follower.
514 *
515 * Handles calling drm_panel_remove_follower() using devm on the follower_dev.
516 *
517 * Return: 0 or an error code.
518 */
519int devm_drm_panel_add_follower(struct device *follower_dev,
520 struct drm_panel_follower *follower)
521{
522 int ret;
523
524 ret = drm_panel_add_follower(follower_dev, follower);
525 if (ret)
526 return ret;
527
528 return devm_add_action_or_reset(follower_dev,
529 drm_panel_remove_follower_void, follower);
530}
531EXPORT_SYMBOL(devm_drm_panel_add_follower);
532
533#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE)
534/**
535 * drm_panel_of_backlight - use backlight device node for backlight
536 * @panel: DRM panel
537 *
538 * Use this function to enable backlight handling if your panel
539 * uses device tree and has a backlight phandle.
540 *
541 * When the panel is enabled backlight will be enabled after a
542 * successful call to &drm_panel_funcs.enable()
543 *
544 * When the panel is disabled backlight will be disabled before the
545 * call to &drm_panel_funcs.disable().
546 *
547 * A typical implementation for a panel driver supporting device tree
548 * will call this function at probe time. Backlight will then be handled
549 * transparently without requiring any intervention from the driver.
550 * drm_panel_of_backlight() must be called after the call to drm_panel_init().
551 *
552 * Return: 0 on success or a negative error code on failure.
553 */
554int drm_panel_of_backlight(struct drm_panel *panel)
555{
556 struct backlight_device *backlight;
557
558 if (!panel || !panel->dev)
559 return -EINVAL;
560
561 backlight = devm_of_find_backlight(panel->dev);
562
563 if (IS_ERR(backlight))
564 return PTR_ERR(backlight);
565
566 panel->backlight = backlight;
567 return 0;
568}
569EXPORT_SYMBOL(drm_panel_of_backlight);
570#endif
571
572MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
573MODULE_DESCRIPTION("DRM panel infrastructure");
574MODULE_LICENSE("GPL and additional rights");
1/*
2 * Copyright (C) 2013, NVIDIA Corporation. All rights reserved.
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#include <drm/drm_panel.h>
29
30static DEFINE_MUTEX(panel_lock);
31static LIST_HEAD(panel_list);
32
33/**
34 * DOC: drm panel
35 *
36 * The DRM panel helpers allow drivers to register panel objects with a
37 * central registry and provide functions to retrieve those panels in display
38 * drivers.
39 *
40 * For easy integration into drivers using the &drm_bridge infrastructure please
41 * take look at drm_panel_bridge_add() and devm_drm_panel_bridge_add().
42 */
43
44/**
45 * drm_panel_init - initialize a panel
46 * @panel: DRM panel
47 *
48 * Sets up internal fields of the panel so that it can subsequently be added
49 * to the registry.
50 */
51void drm_panel_init(struct drm_panel *panel)
52{
53 INIT_LIST_HEAD(&panel->list);
54}
55EXPORT_SYMBOL(drm_panel_init);
56
57/**
58 * drm_panel_add - add a panel to the global registry
59 * @panel: panel to add
60 *
61 * Add a panel to the global registry so that it can be looked up by display
62 * drivers.
63 *
64 * Return: 0 on success or a negative error code on failure.
65 */
66int drm_panel_add(struct drm_panel *panel)
67{
68 mutex_lock(&panel_lock);
69 list_add_tail(&panel->list, &panel_list);
70 mutex_unlock(&panel_lock);
71
72 return 0;
73}
74EXPORT_SYMBOL(drm_panel_add);
75
76/**
77 * drm_panel_remove - remove a panel from the global registry
78 * @panel: DRM panel
79 *
80 * Removes a panel from the global registry.
81 */
82void drm_panel_remove(struct drm_panel *panel)
83{
84 mutex_lock(&panel_lock);
85 list_del_init(&panel->list);
86 mutex_unlock(&panel_lock);
87}
88EXPORT_SYMBOL(drm_panel_remove);
89
90/**
91 * drm_panel_attach - attach a panel to a connector
92 * @panel: DRM panel
93 * @connector: DRM connector
94 *
95 * After obtaining a pointer to a DRM panel a display driver calls this
96 * function to attach a panel to a connector.
97 *
98 * An error is returned if the panel is already attached to another connector.
99 *
100 * When unloading, the driver should detach from the panel by calling
101 * drm_panel_detach().
102 *
103 * Return: 0 on success or a negative error code on failure.
104 */
105int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
106{
107 if (panel->connector)
108 return -EBUSY;
109
110 panel->connector = connector;
111 panel->drm = connector->dev;
112
113 return 0;
114}
115EXPORT_SYMBOL(drm_panel_attach);
116
117/**
118 * drm_panel_detach - detach a panel from a connector
119 * @panel: DRM panel
120 *
121 * Detaches a panel from the connector it is attached to. If a panel is not
122 * attached to any connector this is effectively a no-op.
123 *
124 * This function should not be called by the panel device itself. It
125 * is only for the drm device that called drm_panel_attach().
126 */
127void drm_panel_detach(struct drm_panel *panel)
128{
129 panel->connector = NULL;
130 panel->drm = NULL;
131}
132EXPORT_SYMBOL(drm_panel_detach);
133
134/**
135 * drm_panel_prepare - power on a panel
136 * @panel: DRM panel
137 *
138 * Calling this function will enable power and deassert any reset signals to
139 * the panel. After this has completed it is possible to communicate with any
140 * integrated circuitry via a command bus.
141 *
142 * Return: 0 on success or a negative error code on failure.
143 */
144int drm_panel_prepare(struct drm_panel *panel)
145{
146 if (panel && panel->funcs && panel->funcs->prepare)
147 return panel->funcs->prepare(panel);
148
149 return panel ? -ENOSYS : -EINVAL;
150}
151EXPORT_SYMBOL(drm_panel_prepare);
152
153/**
154 * drm_panel_unprepare - power off a panel
155 * @panel: DRM panel
156 *
157 * Calling this function will completely power off a panel (assert the panel's
158 * reset, turn off power supplies, ...). After this function has completed, it
159 * is usually no longer possible to communicate with the panel until another
160 * call to drm_panel_prepare().
161 *
162 * Return: 0 on success or a negative error code on failure.
163 */
164int drm_panel_unprepare(struct drm_panel *panel)
165{
166 if (panel && panel->funcs && panel->funcs->unprepare)
167 return panel->funcs->unprepare(panel);
168
169 return panel ? -ENOSYS : -EINVAL;
170}
171EXPORT_SYMBOL(drm_panel_unprepare);
172
173/**
174 * drm_panel_enable - enable a panel
175 * @panel: DRM panel
176 *
177 * Calling this function will cause the panel display drivers to be turned on
178 * and the backlight to be enabled. Content will be visible on screen after
179 * this call completes.
180 *
181 * Return: 0 on success or a negative error code on failure.
182 */
183int drm_panel_enable(struct drm_panel *panel)
184{
185 if (panel && panel->funcs && panel->funcs->enable)
186 return panel->funcs->enable(panel);
187
188 return panel ? -ENOSYS : -EINVAL;
189}
190EXPORT_SYMBOL(drm_panel_enable);
191
192/**
193 * drm_panel_disable - disable a panel
194 * @panel: DRM panel
195 *
196 * This will typically turn off the panel's backlight or disable the display
197 * drivers. For smart panels it should still be possible to communicate with
198 * the integrated circuitry via any command bus after this call.
199 *
200 * Return: 0 on success or a negative error code on failure.
201 */
202int drm_panel_disable(struct drm_panel *panel)
203{
204 if (panel && panel->funcs && panel->funcs->disable)
205 return panel->funcs->disable(panel);
206
207 return panel ? -ENOSYS : -EINVAL;
208}
209EXPORT_SYMBOL(drm_panel_disable);
210
211/**
212 * drm_panel_get_modes - probe the available display modes of a panel
213 * @panel: DRM panel
214 *
215 * The modes probed from the panel are automatically added to the connector
216 * that the panel is attached to.
217 *
218 * Return: The number of modes available from the panel on success or a
219 * negative error code on failure.
220 */
221int drm_panel_get_modes(struct drm_panel *panel)
222{
223 if (panel && panel->funcs && panel->funcs->get_modes)
224 return panel->funcs->get_modes(panel);
225
226 return panel ? -ENOSYS : -EINVAL;
227}
228EXPORT_SYMBOL(drm_panel_get_modes);
229
230#ifdef CONFIG_OF
231/**
232 * of_drm_find_panel - look up a panel using a device tree node
233 * @np: device tree node of the panel
234 *
235 * Searches the set of registered panels for one that matches the given device
236 * tree node. If a matching panel is found, return a pointer to it.
237 *
238 * Return: A pointer to the panel registered for the specified device tree
239 * node or an ERR_PTR() if no panel matching the device tree node can be found.
240 *
241 * Possible error codes returned by this function:
242 *
243 * - EPROBE_DEFER: the panel device has not been probed yet, and the caller
244 * should retry later
245 * - ENODEV: the device is not available (status != "okay" or "ok")
246 */
247struct drm_panel *of_drm_find_panel(const struct device_node *np)
248{
249 struct drm_panel *panel;
250
251 if (!of_device_is_available(np))
252 return ERR_PTR(-ENODEV);
253
254 mutex_lock(&panel_lock);
255
256 list_for_each_entry(panel, &panel_list, list) {
257 if (panel->dev->of_node == np) {
258 mutex_unlock(&panel_lock);
259 return panel;
260 }
261 }
262
263 mutex_unlock(&panel_lock);
264 return ERR_PTR(-EPROBE_DEFER);
265}
266EXPORT_SYMBOL(of_drm_find_panel);
267#endif
268
269MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
270MODULE_DESCRIPTION("DRM panel infrastructure");
271MODULE_LICENSE("GPL and additional rights");