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_edid.h>
19 #include <drm/drm_print.h>
20 #include <drm/drm_probe_helper.h>
21 
22 struct simple_bridge_info {
23 	const struct drm_bridge_timings *timings;
24 	unsigned int connector_type;
25 };
26 
27 struct simple_bridge {
28 	struct drm_bridge	bridge;
29 	struct drm_connector	connector;
30 
31 	const struct simple_bridge_info *info;
32 
33 	struct drm_bridge	*next_bridge;
34 	struct regulator	*vdd;
35 	struct gpio_desc	*enable;
36 };
37 
38 static inline struct simple_bridge *
39 drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
40 {
41 	return container_of(bridge, struct simple_bridge, bridge);
42 }
43 
44 static inline struct simple_bridge *
45 drm_connector_to_simple_bridge(struct drm_connector *connector)
46 {
47 	return container_of(connector, struct simple_bridge, connector);
48 }
49 
50 static int simple_bridge_get_modes(struct drm_connector *connector)
51 {
52 	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
53 	struct edid *edid;
54 	int ret;
55 
56 	if (sbridge->next_bridge->ops & DRM_BRIDGE_OP_EDID) {
57 		edid = drm_bridge_get_edid(sbridge->next_bridge, connector);
58 		if (!edid)
59 			DRM_INFO("EDID read failed. Fallback to standard modes\n");
60 	} else {
61 		edid = NULL;
62 	}
63 
64 	if (!edid) {
65 		/*
66 		 * In case we cannot retrieve the EDIDs (missing or broken DDC
67 		 * bus from the next bridge), fallback on the XGA standards and
68 		 * prefer a mode pretty much anyone can handle.
69 		 */
70 		ret = drm_add_modes_noedid(connector, 1920, 1200);
71 		drm_set_preferred_mode(connector, 1024, 768);
72 		return ret;
73 	}
74 
75 	drm_connector_update_edid_property(connector, edid);
76 	ret = drm_add_edid_modes(connector, edid);
77 	kfree(edid);
78 
79 	return ret;
80 }
81 
82 static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
83 	.get_modes	= simple_bridge_get_modes,
84 };
85 
86 static enum drm_connector_status
87 simple_bridge_connector_detect(struct drm_connector *connector, bool force)
88 {
89 	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
90 
91 	return drm_bridge_detect(sbridge->next_bridge);
92 }
93 
94 static const struct drm_connector_funcs simple_bridge_con_funcs = {
95 	.detect			= simple_bridge_connector_detect,
96 	.fill_modes		= drm_helper_probe_single_connector_modes,
97 	.destroy		= drm_connector_cleanup,
98 	.reset			= drm_atomic_helper_connector_reset,
99 	.atomic_duplicate_state	= drm_atomic_helper_connector_duplicate_state,
100 	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
101 };
102 
103 static int simple_bridge_attach(struct drm_bridge *bridge,
104 				enum drm_bridge_attach_flags flags)
105 {
106 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
107 	int ret;
108 
109 	ret = drm_bridge_attach(bridge->encoder, sbridge->next_bridge, bridge,
110 				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
111 	if (ret < 0)
112 		return ret;
113 
114 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
115 		return 0;
116 
117 	if (!bridge->encoder) {
118 		DRM_ERROR("Missing encoder\n");
119 		return -ENODEV;
120 	}
121 
122 	drm_connector_helper_add(&sbridge->connector,
123 				 &simple_bridge_con_helper_funcs);
124 	ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
125 					  &simple_bridge_con_funcs,
126 					  sbridge->info->connector_type,
127 					  sbridge->next_bridge->ddc);
128 	if (ret) {
129 		DRM_ERROR("Failed to initialize connector\n");
130 		return ret;
131 	}
132 
133 	drm_connector_attach_encoder(&sbridge->connector, bridge->encoder);
134 
135 	return 0;
136 }
137 
138 static void simple_bridge_enable(struct drm_bridge *bridge)
139 {
140 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
141 	int ret;
142 
143 	if (sbridge->vdd) {
144 		ret = regulator_enable(sbridge->vdd);
145 		if (ret)
146 			DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
147 	}
148 
149 	gpiod_set_value_cansleep(sbridge->enable, 1);
150 }
151 
152 static void simple_bridge_disable(struct drm_bridge *bridge)
153 {
154 	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
155 
156 	gpiod_set_value_cansleep(sbridge->enable, 0);
157 
158 	if (sbridge->vdd)
159 		regulator_disable(sbridge->vdd);
160 }
161 
162 static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
163 	.attach		= simple_bridge_attach,
164 	.enable		= simple_bridge_enable,
165 	.disable	= simple_bridge_disable,
166 };
167 
168 static int simple_bridge_probe(struct platform_device *pdev)
169 {
170 	struct simple_bridge *sbridge;
171 	struct device_node *remote;
172 
173 	sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
174 	if (!sbridge)
175 		return -ENOMEM;
176 	platform_set_drvdata(pdev, sbridge);
177 
178 	sbridge->info = of_device_get_match_data(&pdev->dev);
179 
180 	/* Get the next bridge in the pipeline. */
181 	remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
182 	if (!remote)
183 		return -EINVAL;
184 
185 	sbridge->next_bridge = of_drm_find_bridge(remote);
186 	of_node_put(remote);
187 
188 	if (!sbridge->next_bridge) {
189 		dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
190 		return -EPROBE_DEFER;
191 	}
192 
193 	/* Get the regulator and GPIO resources. */
194 	sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
195 	if (IS_ERR(sbridge->vdd)) {
196 		int ret = PTR_ERR(sbridge->vdd);
197 		if (ret == -EPROBE_DEFER)
198 			return -EPROBE_DEFER;
199 		sbridge->vdd = NULL;
200 		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
201 	}
202 
203 	sbridge->enable = devm_gpiod_get_optional(&pdev->dev, "enable",
204 						  GPIOD_OUT_LOW);
205 	if (IS_ERR(sbridge->enable)) {
206 		if (PTR_ERR(sbridge->enable) != -EPROBE_DEFER)
207 			dev_err(&pdev->dev, "Unable to retrieve enable GPIO\n");
208 		return PTR_ERR(sbridge->enable);
209 	}
210 
211 	/* Register the bridge. */
212 	sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
213 	sbridge->bridge.of_node = pdev->dev.of_node;
214 	sbridge->bridge.timings = sbridge->info->timings;
215 
216 	drm_bridge_add(&sbridge->bridge);
217 
218 	return 0;
219 }
220 
221 static int simple_bridge_remove(struct platform_device *pdev)
222 {
223 	struct simple_bridge *sbridge = platform_get_drvdata(pdev);
224 
225 	drm_bridge_remove(&sbridge->bridge);
226 
227 	return 0;
228 }
229 
230 /*
231  * We assume the ADV7123 DAC is the "default" for historical reasons
232  * Information taken from the ADV7123 datasheet, revision D.
233  * NOTE: the ADV7123EP seems to have other timings and need a new timings
234  * set if used.
235  */
236 static const struct drm_bridge_timings default_bridge_timings = {
237 	/* Timing specifications, datasheet page 7 */
238 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
239 	.setup_time_ps = 500,
240 	.hold_time_ps = 1500,
241 };
242 
243 /*
244  * Information taken from the THS8134, THS8134A, THS8134B datasheet named
245  * "SLVS205D", dated May 1990, revised March 2000.
246  */
247 static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
248 	/* From timing diagram, datasheet page 9 */
249 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
250 	/* From datasheet, page 12 */
251 	.setup_time_ps = 3000,
252 	/* I guess this means latched input */
253 	.hold_time_ps = 0,
254 };
255 
256 /*
257  * Information taken from the THS8135 datasheet named "SLAS343B", dated
258  * May 2001, revised April 2013.
259  */
260 static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
261 	/* From timing diagram, datasheet page 14 */
262 	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
263 	/* From datasheet, page 16 */
264 	.setup_time_ps = 2000,
265 	.hold_time_ps = 500,
266 };
267 
268 static const struct of_device_id simple_bridge_match[] = {
269 	{
270 		.compatible = "dumb-vga-dac",
271 		.data = &(const struct simple_bridge_info) {
272 			.connector_type = DRM_MODE_CONNECTOR_VGA,
273 		},
274 	}, {
275 		.compatible = "adi,adv7123",
276 		.data = &(const struct simple_bridge_info) {
277 			.timings = &default_bridge_timings,
278 			.connector_type = DRM_MODE_CONNECTOR_VGA,
279 		},
280 	}, {
281 		.compatible = "ti,opa362",
282 		.data = &(const struct simple_bridge_info) {
283 			.connector_type = DRM_MODE_CONNECTOR_Composite,
284 		},
285 	}, {
286 		.compatible = "ti,ths8135",
287 		.data = &(const struct simple_bridge_info) {
288 			.timings = &ti_ths8135_bridge_timings,
289 			.connector_type = DRM_MODE_CONNECTOR_VGA,
290 		},
291 	}, {
292 		.compatible = "ti,ths8134",
293 		.data = &(const struct simple_bridge_info) {
294 			.timings = &ti_ths8134_bridge_timings,
295 			.connector_type = DRM_MODE_CONNECTOR_VGA,
296 		},
297 	},
298 	{},
299 };
300 MODULE_DEVICE_TABLE(of, simple_bridge_match);
301 
302 static struct platform_driver simple_bridge_driver = {
303 	.probe	= simple_bridge_probe,
304 	.remove	= simple_bridge_remove,
305 	.driver		= {
306 		.name		= "simple-bridge",
307 		.of_match_table	= simple_bridge_match,
308 	},
309 };
310 module_platform_driver(simple_bridge_driver);
311 
312 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
313 MODULE_DESCRIPTION("Simple DRM bridge driver");
314 MODULE_LICENSE("GPL");
315