1 /*
2 * Copyright (C) 2015-2016 Free Electrons
3 * Copyright (C) 2015-2016 NextThing Co
4 *
5 * Maxime Ripard <maxime.ripard@free-electrons.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
11 */
12
13 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/of_graph.h>
16 #include <linux/regulator/consumer.h>
17
18 #include <drm/drmP.h>
19 #include <drm/drm_atomic_helper.h>
20 #include <drm/drm_crtc.h>
21 #include <drm/drm_crtc_helper.h>
22
23 struct dumb_vga {
24 struct drm_bridge bridge;
25 struct drm_connector connector;
26
27 struct i2c_adapter *ddc;
28 struct regulator *vdd;
29 };
30
31 static inline struct dumb_vga *
drm_bridge_to_dumb_vga(struct drm_bridge * bridge)32 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
33 {
34 return container_of(bridge, struct dumb_vga, bridge);
35 }
36
37 static inline struct dumb_vga *
drm_connector_to_dumb_vga(struct drm_connector * connector)38 drm_connector_to_dumb_vga(struct drm_connector *connector)
39 {
40 return container_of(connector, struct dumb_vga, connector);
41 }
42
dumb_vga_get_modes(struct drm_connector * connector)43 static int dumb_vga_get_modes(struct drm_connector *connector)
44 {
45 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
46 struct edid *edid;
47 int ret;
48
49 if (IS_ERR(vga->ddc))
50 goto fallback;
51
52 edid = drm_get_edid(connector, vga->ddc);
53 if (!edid) {
54 DRM_INFO("EDID readout failed, falling back to standard modes\n");
55 goto fallback;
56 }
57
58 drm_connector_update_edid_property(connector, edid);
59 ret = drm_add_edid_modes(connector, edid);
60 kfree(edid);
61 return ret;
62
63 fallback:
64 /*
65 * In case we cannot retrieve the EDIDs (broken or missing i2c
66 * bus), fallback on the XGA standards
67 */
68 ret = drm_add_modes_noedid(connector, 1920, 1200);
69
70 /* And prefer a mode pretty much anyone can handle */
71 drm_set_preferred_mode(connector, 1024, 768);
72
73 return ret;
74 }
75
76 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
77 .get_modes = dumb_vga_get_modes,
78 };
79
80 static enum drm_connector_status
dumb_vga_connector_detect(struct drm_connector * connector,bool force)81 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
82 {
83 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
84
85 /*
86 * Even if we have an I2C bus, we can't assume that the cable
87 * is disconnected if drm_probe_ddc fails. Some cables don't
88 * wire the DDC pins, or the I2C bus might not be working at
89 * all.
90 */
91 if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
92 return connector_status_connected;
93
94 return connector_status_unknown;
95 }
96
97 static const struct drm_connector_funcs dumb_vga_con_funcs = {
98 .detect = dumb_vga_connector_detect,
99 .fill_modes = drm_helper_probe_single_connector_modes,
100 .destroy = drm_connector_cleanup,
101 .reset = drm_atomic_helper_connector_reset,
102 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
103 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
104 };
105
dumb_vga_attach(struct drm_bridge * bridge)106 static int dumb_vga_attach(struct drm_bridge *bridge)
107 {
108 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
109 int ret;
110
111 if (!bridge->encoder) {
112 DRM_ERROR("Missing encoder\n");
113 return -ENODEV;
114 }
115
116 drm_connector_helper_add(&vga->connector,
117 &dumb_vga_con_helper_funcs);
118 ret = drm_connector_init(bridge->dev, &vga->connector,
119 &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
120 if (ret) {
121 DRM_ERROR("Failed to initialize connector\n");
122 return ret;
123 }
124
125 drm_connector_attach_encoder(&vga->connector,
126 bridge->encoder);
127
128 return 0;
129 }
130
dumb_vga_enable(struct drm_bridge * bridge)131 static void dumb_vga_enable(struct drm_bridge *bridge)
132 {
133 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
134 int ret = 0;
135
136 if (vga->vdd)
137 ret = regulator_enable(vga->vdd);
138
139 if (ret)
140 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
141 }
142
dumb_vga_disable(struct drm_bridge * bridge)143 static void dumb_vga_disable(struct drm_bridge *bridge)
144 {
145 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
146
147 if (vga->vdd)
148 regulator_disable(vga->vdd);
149 }
150
151 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
152 .attach = dumb_vga_attach,
153 .enable = dumb_vga_enable,
154 .disable = dumb_vga_disable,
155 };
156
dumb_vga_retrieve_ddc(struct device * dev)157 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
158 {
159 struct device_node *phandle, *remote;
160 struct i2c_adapter *ddc;
161
162 remote = of_graph_get_remote_node(dev->of_node, 1, -1);
163 if (!remote)
164 return ERR_PTR(-EINVAL);
165
166 phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
167 of_node_put(remote);
168 if (!phandle)
169 return ERR_PTR(-ENODEV);
170
171 ddc = of_get_i2c_adapter_by_node(phandle);
172 of_node_put(phandle);
173 if (!ddc)
174 return ERR_PTR(-EPROBE_DEFER);
175
176 return ddc;
177 }
178
dumb_vga_probe(struct platform_device * pdev)179 static int dumb_vga_probe(struct platform_device *pdev)
180 {
181 struct dumb_vga *vga;
182
183 vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
184 if (!vga)
185 return -ENOMEM;
186 platform_set_drvdata(pdev, vga);
187
188 vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
189 if (IS_ERR(vga->vdd)) {
190 int ret = PTR_ERR(vga->vdd);
191 if (ret == -EPROBE_DEFER)
192 return -EPROBE_DEFER;
193 vga->vdd = NULL;
194 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
195 }
196
197 vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
198 if (IS_ERR(vga->ddc)) {
199 if (PTR_ERR(vga->ddc) == -ENODEV) {
200 dev_dbg(&pdev->dev,
201 "No i2c bus specified. Disabling EDID readout\n");
202 } else {
203 dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
204 return PTR_ERR(vga->ddc);
205 }
206 }
207
208 vga->bridge.funcs = &dumb_vga_bridge_funcs;
209 vga->bridge.of_node = pdev->dev.of_node;
210 vga->bridge.timings = of_device_get_match_data(&pdev->dev);
211
212 drm_bridge_add(&vga->bridge);
213
214 return 0;
215 }
216
dumb_vga_remove(struct platform_device * pdev)217 static int dumb_vga_remove(struct platform_device *pdev)
218 {
219 struct dumb_vga *vga = platform_get_drvdata(pdev);
220
221 drm_bridge_remove(&vga->bridge);
222
223 if (!IS_ERR(vga->ddc))
224 i2c_put_adapter(vga->ddc);
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_dac_timings = {
236 /* Timing specifications, datasheet page 7 */
237 .sampling_edge = DRM_BUS_FLAG_PIXDATA_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_dac_timings = {
247 /* From timing diagram, datasheet page 9 */
248 .sampling_edge = DRM_BUS_FLAG_PIXDATA_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_dac_timings = {
260 /* From timing diagram, datasheet page 14 */
261 .sampling_edge = DRM_BUS_FLAG_PIXDATA_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 dumb_vga_match[] = {
268 {
269 .compatible = "dumb-vga-dac",
270 .data = NULL,
271 },
272 {
273 .compatible = "adi,adv7123",
274 .data = &default_dac_timings,
275 },
276 {
277 .compatible = "ti,ths8135",
278 .data = &ti_ths8135_dac_timings,
279 },
280 {
281 .compatible = "ti,ths8134",
282 .data = &ti_ths8134_dac_timings,
283 },
284 {},
285 };
286 MODULE_DEVICE_TABLE(of, dumb_vga_match);
287
288 static struct platform_driver dumb_vga_driver = {
289 .probe = dumb_vga_probe,
290 .remove = dumb_vga_remove,
291 .driver = {
292 .name = "dumb-vga-dac",
293 .of_match_table = dumb_vga_match,
294 },
295 };
296 module_platform_driver(dumb_vga_driver);
297
298 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
299 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
300 MODULE_LICENSE("GPL");
301
