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_device.h>
12 #include <linux/of_graph.h>
13 #include <linux/regulator/consumer.h>
14 
15 #include <drm/drm_atomic_helper.h>
16 #include <drm/drm_bridge.h>
17 #include <drm/drm_crtc.h>
18 #include <drm/drm_print.h>
19 #include <drm/drm_probe_helper.h>
20 
21 struct simple_bridge_info {
22 	const struct drm_bridge_timings *timings;
23 	unsigned int connector_type;
24 };
25 
26 struct simple_bridge {
27 	struct drm_bridge	bridge;
28 	struct drm_connector	connector;
29 
30 	const struct simple_bridge_info *info;
31 
32 	struct drm_bridge	*next_bridge;
33 	struct regulator	*vdd;
34 	struct gpio_desc	*enable;
35 };
36 
37 static inline struct simple_bridge *
38 drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
39 {
40 	return container_of(bridge, struct simple_bridge, bridge);
41 }
42 
43 static inline struct simple_bridge *
44 drm_connector_to_simple_bridge(struct drm_connector *connector)
45 {
46 	return container_of(connector, struct simple_bridge, connector);
47 }
48 
49 static int simple_bridge_get_modes(struct drm_connector *connector)
50 {
51 	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
52 	struct edid *edid;
53 	int ret;
54 
55 	if (sbridge->next_bridge->ops & DRM_BRIDGE_OP_EDID) {
56 		edid = drm_bridge_get_edid(sbridge->next_bridge, connector);
57 		if (!edid)
58 			DRM_INFO("EDID read failed. Fallback to standard modes\n");
59 	} else {
60 		edid = NULL;
61 	}
62 
63 	if (!edid) {
64 		/*
65 		 * In case we cannot retrieve the EDIDs (missing or broken DDC
66 		 * bus from the next bridge), fallback on the XGA standards and
67 		 * prefer a mode pretty much anyone can handle.
68 		 */
69 		ret = drm_add_modes_noedid(connector, 1920, 1200);
70 		drm_set_preferred_mode(connector, 1024, 768);
71 		return ret;
72 	}
73 
74 	drm_connector_update_edid_property(connector, edid);
75 	ret = drm_add_edid_modes(connector, edid);
76 	kfree(edid);
77 
78 	return ret;
79 }
80 
81 static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
82 	.get_modes	= simple_bridge_get_modes,
83 };
84 
85 static enum drm_connector_status
86 simple_bridge_connector_detect(struct drm_connector *connector, bool force)
87 {
88 	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
89 
90 	return drm_bridge_detect(sbridge->next_bridge);
91 }
92 
93 static const struct drm_connector_funcs simple_bridge_con_funcs = {
94 	.detect			= simple_bridge_connector_detect,
95 	.fill_modes		= drm_helper_probe_single_connector_modes,
96 	.destroy		= drm_connector_cleanup,
97 	.reset			= drm_atomic_helper_connector_reset,
98 	.atomic_duplicate_state	= drm_atomic_helper_connector_duplicate_state,
99 	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
100 };
101 
102 static int simple_bridge_attach(struct drm_bridge *bridge,
103 				enum drm_bridge_attach_flags flags)
104 {
105 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
106 	int ret;
107 
108 	ret = drm_bridge_attach(bridge->encoder, sbridge->next_bridge, bridge,
109 				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
110 	if (ret < 0)
111 		return ret;
112 
113 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
114 		return 0;
115 
116 	if (!bridge->encoder) {
117 		DRM_ERROR("Missing encoder\n");
118 		return -ENODEV;
119 	}
120 
121 	drm_connector_helper_add(&sbridge->connector,
122 				 &simple_bridge_con_helper_funcs);
123 	ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
124 					  &simple_bridge_con_funcs,
125 					  sbridge->info->connector_type,
126 					  sbridge->next_bridge->ddc);
127 	if (ret) {
128 		DRM_ERROR("Failed to initialize connector\n");
129 		return ret;
130 	}
131 
132 	drm_connector_attach_encoder(&sbridge->connector, bridge->encoder);
133 
134 	return 0;
135 }
136 
137 static void simple_bridge_enable(struct drm_bridge *bridge)
138 {
139 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
140 	int ret;
141 
142 	if (sbridge->vdd) {
143 		ret = regulator_enable(sbridge->vdd);
144 		if (ret)
145 			DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
146 	}
147 
148 	gpiod_set_value_cansleep(sbridge->enable, 1);
149 }
150 
151 static void simple_bridge_disable(struct drm_bridge *bridge)
152 {
153 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
154 
155 	gpiod_set_value_cansleep(sbridge->enable, 0);
156 
157 	if (sbridge->vdd)
158 		regulator_disable(sbridge->vdd);
159 }
160 
161 static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
162 	.attach		= simple_bridge_attach,
163 	.enable		= simple_bridge_enable,
164 	.disable	= simple_bridge_disable,
165 };
166 
167 static int simple_bridge_probe(struct platform_device *pdev)
168 {
169 	struct simple_bridge *sbridge;
170 	struct device_node *remote;
171 
172 	sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
173 	if (!sbridge)
174 		return -ENOMEM;
175 	platform_set_drvdata(pdev, sbridge);
176 
177 	sbridge->info = of_device_get_match_data(&pdev->dev);
178 
179 	/* Get the next bridge in the pipeline. */
180 	remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
181 	if (!remote)
182 		return -EINVAL;
183 
184 	sbridge->next_bridge = of_drm_find_bridge(remote);
185 	of_node_put(remote);
186 
187 	if (!sbridge->next_bridge) {
188 		dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
189 		return -EPROBE_DEFER;
190 	}
191 
192 	/* Get the regulator and GPIO resources. */
193 	sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
194 	if (IS_ERR(sbridge->vdd)) {
195 		int ret = PTR_ERR(sbridge->vdd);
196 		if (ret == -EPROBE_DEFER)
197 			return -EPROBE_DEFER;
198 		sbridge->vdd = NULL;
199 		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
200 	}
201 
202 	sbridge->enable = devm_gpiod_get_optional(&pdev->dev, "enable",
203 						  GPIOD_OUT_LOW);
204 	if (IS_ERR(sbridge->enable)) {
205 		if (PTR_ERR(sbridge->enable) != -EPROBE_DEFER)
206 			dev_err(&pdev->dev, "Unable to retrieve enable GPIO\n");
207 		return PTR_ERR(sbridge->enable);
208 	}
209 
210 	/* Register the bridge. */
211 	sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
212 	sbridge->bridge.of_node = pdev->dev.of_node;
213 	sbridge->bridge.timings = sbridge->info->timings;
214 
215 	drm_bridge_add(&sbridge->bridge);
216 
217 	return 0;
218 }
219 
220 static int simple_bridge_remove(struct platform_device *pdev)
221 {
222 	struct simple_bridge *sbridge = platform_get_drvdata(pdev);
223 
224 	drm_bridge_remove(&sbridge->bridge);
225 
226 	return 0;
227 }
228 
229 /*
230  * We assume the ADV7123 DAC is the "default" for historical reasons
231  * Information taken from the ADV7123 datasheet, revision D.
232  * NOTE: the ADV7123EP seems to have other timings and need a new timings
233  * set if used.
234  */
235 static const struct drm_bridge_timings default_bridge_timings = {
236 	/* Timing specifications, datasheet page 7 */
237 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
238 	.setup_time_ps = 500,
239 	.hold_time_ps = 1500,
240 };
241 
242 /*
243  * Information taken from the THS8134, THS8134A, THS8134B datasheet named
244  * "SLVS205D", dated May 1990, revised March 2000.
245  */
246 static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
247 	/* From timing diagram, datasheet page 9 */
248 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
249 	/* From datasheet, page 12 */
250 	.setup_time_ps = 3000,
251 	/* I guess this means latched input */
252 	.hold_time_ps = 0,
253 };
254 
255 /*
256  * Information taken from the THS8135 datasheet named "SLAS343B", dated
257  * May 2001, revised April 2013.
258  */
259 static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
260 	/* From timing diagram, datasheet page 14 */
261 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
262 	/* From datasheet, page 16 */
263 	.setup_time_ps = 2000,
264 	.hold_time_ps = 500,
265 };
266 
267 static const struct of_device_id simple_bridge_match[] = {
268 	{
269 		.compatible = "dumb-vga-dac",
270 		.data = &(const struct simple_bridge_info) {
271 			.connector_type = DRM_MODE_CONNECTOR_VGA,
272 		},
273 	}, {
274 		.compatible = "adi,adv7123",
275 		.data = &(const struct simple_bridge_info) {
276 			.timings = &default_bridge_timings,
277 			.connector_type = DRM_MODE_CONNECTOR_VGA,
278 		},
279 	}, {
280 		.compatible = "ti,opa362",
281 		.data = &(const struct simple_bridge_info) {
282 			.connector_type = DRM_MODE_CONNECTOR_Composite,
283 		},
284 	}, {
285 		.compatible = "ti,ths8135",
286 		.data = &(const struct simple_bridge_info) {
287 			.timings = &ti_ths8135_bridge_timings,
288 			.connector_type = DRM_MODE_CONNECTOR_VGA,
289 		},
290 	}, {
291 		.compatible = "ti,ths8134",
292 		.data = &(const struct simple_bridge_info) {
293 			.timings = &ti_ths8134_bridge_timings,
294 			.connector_type = DRM_MODE_CONNECTOR_VGA,
295 		},
296 	},
297 	{},
298 };
299 MODULE_DEVICE_TABLE(of, simple_bridge_match);
300 
301 static struct platform_driver simple_bridge_driver = {
302 	.probe	= simple_bridge_probe,
303 	.remove	= simple_bridge_remove,
304 	.driver		= {
305 		.name		= "simple-bridge",
306 		.of_match_table	= simple_bridge_match,
307 	},
308 };
309 module_platform_driver(simple_bridge_driver);
310 
311 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
312 MODULE_DESCRIPTION("Simple DRM bridge driver");
313 MODULE_LICENSE("GPL");
314