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_graph.h>
15
16 #include <drm/drmP.h>
17 #include <drm/drm_atomic_helper.h>
18 #include <drm/drm_crtc.h>
19 #include <drm/drm_crtc_helper.h>
20
21 struct dumb_vga {
22 struct drm_bridge bridge;
23 struct drm_connector connector;
24
25 struct i2c_adapter *ddc;
26 };
27
28 static inline struct dumb_vga *
drm_bridge_to_dumb_vga(struct drm_bridge * bridge)29 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
30 {
31 return container_of(bridge, struct dumb_vga, bridge);
32 }
33
34 static inline struct dumb_vga *
drm_connector_to_dumb_vga(struct drm_connector * connector)35 drm_connector_to_dumb_vga(struct drm_connector *connector)
36 {
37 return container_of(connector, struct dumb_vga, connector);
38 }
39
dumb_vga_get_modes(struct drm_connector * connector)40 static int dumb_vga_get_modes(struct drm_connector *connector)
41 {
42 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
43 struct edid *edid;
44 int ret;
45
46 if (IS_ERR(vga->ddc))
47 goto fallback;
48
49 edid = drm_get_edid(connector, vga->ddc);
50 if (!edid) {
51 DRM_INFO("EDID readout failed, falling back to standard modes\n");
52 goto fallback;
53 }
54
55 drm_mode_connector_update_edid_property(connector, edid);
56 return drm_add_edid_modes(connector, edid);
57
58 fallback:
59 /*
60 * In case we cannot retrieve the EDIDs (broken or missing i2c
61 * bus), fallback on the XGA standards
62 */
63 ret = drm_add_modes_noedid(connector, 1920, 1200);
64
65 /* And prefer a mode pretty much anyone can handle */
66 drm_set_preferred_mode(connector, 1024, 768);
67
68 return ret;
69 }
70
71 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
72 .get_modes = dumb_vga_get_modes,
73 };
74
75 static enum drm_connector_status
dumb_vga_connector_detect(struct drm_connector * connector,bool force)76 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
77 {
78 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
79
80 /*
81 * Even if we have an I2C bus, we can't assume that the cable
82 * is disconnected if drm_probe_ddc fails. Some cables don't
83 * wire the DDC pins, or the I2C bus might not be working at
84 * all.
85 */
86 if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
87 return connector_status_connected;
88
89 return connector_status_unknown;
90 }
91
92 static const struct drm_connector_funcs dumb_vga_con_funcs = {
93 .dpms = drm_atomic_helper_connector_dpms,
94 .detect = dumb_vga_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
dumb_vga_attach(struct drm_bridge * bridge)102 static int dumb_vga_attach(struct drm_bridge *bridge)
103 {
104 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
105 int ret;
106
107 if (!bridge->encoder) {
108 DRM_ERROR("Missing encoder\n");
109 return -ENODEV;
110 }
111
112 drm_connector_helper_add(&vga->connector,
113 &dumb_vga_con_helper_funcs);
114 ret = drm_connector_init(bridge->dev, &vga->connector,
115 &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
116 if (ret) {
117 DRM_ERROR("Failed to initialize connector\n");
118 return ret;
119 }
120
121 drm_mode_connector_attach_encoder(&vga->connector,
122 bridge->encoder);
123
124 return 0;
125 }
126
127 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
128 .attach = dumb_vga_attach,
129 };
130
dumb_vga_retrieve_ddc(struct device * dev)131 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
132 {
133 struct device_node *end_node, *phandle, *remote;
134 struct i2c_adapter *ddc;
135
136 end_node = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
137 if (!end_node) {
138 dev_err(dev, "Missing connector endpoint\n");
139 return ERR_PTR(-ENODEV);
140 }
141
142 remote = of_graph_get_remote_port_parent(end_node);
143 of_node_put(end_node);
144 if (!remote) {
145 dev_err(dev, "Enable to parse remote node\n");
146 return ERR_PTR(-EINVAL);
147 }
148
149 phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
150 of_node_put(remote);
151 if (!phandle)
152 return ERR_PTR(-ENODEV);
153
154 ddc = of_get_i2c_adapter_by_node(phandle);
155 of_node_put(phandle);
156 if (!ddc)
157 return ERR_PTR(-EPROBE_DEFER);
158
159 return ddc;
160 }
161
dumb_vga_probe(struct platform_device * pdev)162 static int dumb_vga_probe(struct platform_device *pdev)
163 {
164 struct dumb_vga *vga;
165 int ret;
166
167 vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
168 if (!vga)
169 return -ENOMEM;
170 platform_set_drvdata(pdev, vga);
171
172 vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
173 if (IS_ERR(vga->ddc)) {
174 if (PTR_ERR(vga->ddc) == -ENODEV) {
175 dev_dbg(&pdev->dev,
176 "No i2c bus specified. Disabling EDID readout\n");
177 } else {
178 dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
179 return PTR_ERR(vga->ddc);
180 }
181 }
182
183 vga->bridge.funcs = &dumb_vga_bridge_funcs;
184 vga->bridge.of_node = pdev->dev.of_node;
185
186 ret = drm_bridge_add(&vga->bridge);
187 if (ret && !IS_ERR(vga->ddc))
188 i2c_put_adapter(vga->ddc);
189
190 return ret;
191 }
192
dumb_vga_remove(struct platform_device * pdev)193 static int dumb_vga_remove(struct platform_device *pdev)
194 {
195 struct dumb_vga *vga = platform_get_drvdata(pdev);
196
197 drm_bridge_remove(&vga->bridge);
198
199 if (!IS_ERR(vga->ddc))
200 i2c_put_adapter(vga->ddc);
201
202 return 0;
203 }
204
205 static const struct of_device_id dumb_vga_match[] = {
206 { .compatible = "dumb-vga-dac" },
207 {},
208 };
209 MODULE_DEVICE_TABLE(of, dumb_vga_match);
210
211 static struct platform_driver dumb_vga_driver = {
212 .probe = dumb_vga_probe,
213 .remove = dumb_vga_remove,
214 .driver = {
215 .name = "dumb-vga-dac",
216 .of_match_table = dumb_vga_match,
217 },
218 };
219 module_platform_driver(dumb_vga_driver);
220
221 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
222 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
223 MODULE_LICENSE("GPL");
224