1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2015-2016 Free Electrons
4 * Copyright (C) 2015-2016 NextThing Co
5 *
6 * Maxime Ripard <maxime.ripard@free-electrons.com>
7 */
8
9 #include <linux/gpio/consumer.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/of_graph.h>
13 #include <linux/platform_device.h>
14 #include <linux/regulator/consumer.h>
15
16 #include <drm/drm_atomic_helper.h>
17 #include <drm/drm_bridge.h>
18 #include <drm/drm_crtc.h>
19 #include <drm/drm_edid.h>
20 #include <drm/drm_print.h>
21 #include <drm/drm_probe_helper.h>
22
23 struct simple_bridge_info {
24 const struct drm_bridge_timings *timings;
25 unsigned int connector_type;
26 };
27
28 struct simple_bridge {
29 struct drm_bridge bridge;
30 struct drm_connector connector;
31
32 const struct simple_bridge_info *info;
33
34 struct drm_bridge *next_bridge;
35 struct regulator *vdd;
36 struct gpio_desc *enable;
37 };
38
39 static inline struct simple_bridge *
drm_bridge_to_simple_bridge(struct drm_bridge * bridge)40 drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
41 {
42 return container_of(bridge, struct simple_bridge, bridge);
43 }
44
45 static inline struct simple_bridge *
drm_connector_to_simple_bridge(struct drm_connector * connector)46 drm_connector_to_simple_bridge(struct drm_connector *connector)
47 {
48 return container_of(connector, struct simple_bridge, connector);
49 }
50
simple_bridge_get_modes(struct drm_connector * connector)51 static int simple_bridge_get_modes(struct drm_connector *connector)
52 {
53 struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
54 const struct drm_edid *drm_edid;
55 int ret;
56
57 if (sbridge->next_bridge->ops & DRM_BRIDGE_OP_EDID) {
58 drm_edid = drm_bridge_edid_read(sbridge->next_bridge, connector);
59 if (!drm_edid)
60 DRM_INFO("EDID read failed. Fallback to standard modes\n");
61 } else {
62 drm_edid = NULL;
63 }
64
65 drm_edid_connector_update(connector, drm_edid);
66
67 if (!drm_edid) {
68 /*
69 * In case we cannot retrieve the EDIDs (missing or broken DDC
70 * bus from the next bridge), fallback on the XGA standards and
71 * prefer a mode pretty much anyone can handle.
72 */
73 ret = drm_add_modes_noedid(connector, 1920, 1200);
74 drm_set_preferred_mode(connector, 1024, 768);
75 return ret;
76 }
77
78 ret = drm_edid_connector_add_modes(connector);
79 drm_edid_free(drm_edid);
80
81 return ret;
82 }
83
84 static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
85 .get_modes = simple_bridge_get_modes,
86 };
87
88 static enum drm_connector_status
simple_bridge_connector_detect(struct drm_connector * connector,bool force)89 simple_bridge_connector_detect(struct drm_connector *connector, bool force)
90 {
91 struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
92
93 return drm_bridge_detect(sbridge->next_bridge, connector);
94 }
95
96 static const struct drm_connector_funcs simple_bridge_con_funcs = {
97 .detect = simple_bridge_connector_detect,
98 .fill_modes = drm_helper_probe_single_connector_modes,
99 .destroy = drm_connector_cleanup,
100 .reset = drm_atomic_helper_connector_reset,
101 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
102 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
103 };
104
simple_bridge_attach(struct drm_bridge * bridge,struct drm_encoder * encoder,enum drm_bridge_attach_flags flags)105 static int simple_bridge_attach(struct drm_bridge *bridge,
106 struct drm_encoder *encoder,
107 enum drm_bridge_attach_flags flags)
108 {
109 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
110 int ret;
111
112 ret = drm_bridge_attach(encoder, sbridge->next_bridge, bridge,
113 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
114 if (ret < 0)
115 return ret;
116
117 if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
118 return 0;
119
120 drm_connector_helper_add(&sbridge->connector,
121 &simple_bridge_con_helper_funcs);
122 ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
123 &simple_bridge_con_funcs,
124 sbridge->info->connector_type,
125 sbridge->next_bridge->ddc);
126 if (ret) {
127 DRM_ERROR("Failed to initialize connector\n");
128 return ret;
129 }
130
131 drm_connector_attach_encoder(&sbridge->connector, encoder);
132
133 return 0;
134 }
135
simple_bridge_enable(struct drm_bridge * bridge)136 static void simple_bridge_enable(struct drm_bridge *bridge)
137 {
138 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
139 int ret;
140
141 if (sbridge->vdd) {
142 ret = regulator_enable(sbridge->vdd);
143 if (ret)
144 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
145 }
146
147 gpiod_set_value_cansleep(sbridge->enable, 1);
148 }
149
simple_bridge_disable(struct drm_bridge * bridge)150 static void simple_bridge_disable(struct drm_bridge *bridge)
151 {
152 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
153
154 gpiod_set_value_cansleep(sbridge->enable, 0);
155
156 if (sbridge->vdd)
157 regulator_disable(sbridge->vdd);
158 }
159
160 static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
161 .attach = simple_bridge_attach,
162 .enable = simple_bridge_enable,
163 .disable = simple_bridge_disable,
164 };
165
simple_bridge_probe(struct platform_device * pdev)166 static int simple_bridge_probe(struct platform_device *pdev)
167 {
168 struct simple_bridge *sbridge;
169 struct device_node *remote;
170
171 sbridge = devm_drm_bridge_alloc(&pdev->dev, struct simple_bridge,
172 bridge, &simple_bridge_bridge_funcs);
173 if (IS_ERR(sbridge))
174 return PTR_ERR(sbridge);
175
176 sbridge->info = of_device_get_match_data(&pdev->dev);
177
178 /* Get the next bridge in the pipeline. */
179 remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
180 if (!remote)
181 return -EINVAL;
182
183 sbridge->next_bridge = of_drm_find_bridge(remote);
184 of_node_put(remote);
185
186 if (!sbridge->next_bridge) {
187 dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
188 return -EPROBE_DEFER;
189 }
190
191 /* Get the regulator and GPIO resources. */
192 sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
193 if (IS_ERR(sbridge->vdd)) {
194 int ret = PTR_ERR(sbridge->vdd);
195 if (ret == -EPROBE_DEFER)
196 return -EPROBE_DEFER;
197 sbridge->vdd = NULL;
198 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
199 }
200
201 sbridge->enable = devm_gpiod_get_optional(&pdev->dev, "enable",
202 GPIOD_OUT_LOW);
203 if (IS_ERR(sbridge->enable))
204 return dev_err_probe(&pdev->dev, PTR_ERR(sbridge->enable),
205 "Unable to retrieve enable GPIO\n");
206
207 /* Register the bridge. */
208 sbridge->bridge.of_node = pdev->dev.of_node;
209 sbridge->bridge.timings = sbridge->info->timings;
210
211 return devm_drm_bridge_add(&pdev->dev, &sbridge->bridge);
212 }
213
214 /*
215 * We assume the ADV7123 DAC is the "default" for historical reasons
216 * Information taken from the ADV7123 datasheet, revision D.
217 * NOTE: the ADV7123EP seems to have other timings and need a new timings
218 * set if used.
219 */
220 static const struct drm_bridge_timings default_bridge_timings = {
221 /* Timing specifications, datasheet page 7 */
222 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
223 .setup_time_ps = 500,
224 .hold_time_ps = 1500,
225 };
226
227 /*
228 * Information taken from the THS8134, THS8134A, THS8134B datasheet named
229 * "SLVS205D", dated May 1990, revised March 2000.
230 */
231 static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
232 /* From timing diagram, datasheet page 9 */
233 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
234 /* From datasheet, page 12 */
235 .setup_time_ps = 3000,
236 /* I guess this means latched input */
237 .hold_time_ps = 0,
238 };
239
240 /*
241 * Information taken from the THS8135 datasheet named "SLAS343B", dated
242 * May 2001, revised April 2013.
243 */
244 static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
245 /* From timing diagram, datasheet page 14 */
246 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
247 /* From datasheet, page 16 */
248 .setup_time_ps = 2000,
249 .hold_time_ps = 500,
250 };
251
252 static const struct of_device_id simple_bridge_match[] = {
253 {
254 .compatible = "dumb-vga-dac",
255 .data = &(const struct simple_bridge_info) {
256 .connector_type = DRM_MODE_CONNECTOR_VGA,
257 },
258 }, {
259 .compatible = "adi,adv7123",
260 .data = &(const struct simple_bridge_info) {
261 .timings = &default_bridge_timings,
262 .connector_type = DRM_MODE_CONNECTOR_VGA,
263 },
264 }, {
265 .compatible = "ti,opa362",
266 .data = &(const struct simple_bridge_info) {
267 .connector_type = DRM_MODE_CONNECTOR_Composite,
268 },
269 }, {
270 .compatible = "ti,ths8135",
271 .data = &(const struct simple_bridge_info) {
272 .timings = &ti_ths8135_bridge_timings,
273 .connector_type = DRM_MODE_CONNECTOR_VGA,
274 },
275 }, {
276 .compatible = "ti,ths8134",
277 .data = &(const struct simple_bridge_info) {
278 .timings = &ti_ths8134_bridge_timings,
279 .connector_type = DRM_MODE_CONNECTOR_VGA,
280 },
281 },
282 {},
283 };
284 MODULE_DEVICE_TABLE(of, simple_bridge_match);
285
286 static struct platform_driver simple_bridge_driver = {
287 .probe = simple_bridge_probe,
288 .driver = {
289 .name = "simple-bridge",
290 .of_match_table = simple_bridge_match,
291 },
292 };
293 module_platform_driver(simple_bridge_driver);
294
295 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
296 MODULE_DESCRIPTION("Simple DRM bridge driver");
297 MODULE_LICENSE("GPL");
298