tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#include <linux/regulator/consumer.h>
16
17#include <drm/drmP.h>
18#include <drm/drm_atomic_helper.h>
19#include <drm/drm_crtc.h>
20#include <drm/drm_crtc_helper.h>
21
22struct dumb_vga {
23 struct drm_bridge bridge;
24 struct drm_connector connector;
25
26 struct i2c_adapter *ddc;
27 struct regulator *vdd;
28};
29
30static inline struct dumb_vga *
31drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
32{
33 return container_of(bridge, struct dumb_vga, bridge);
34}
35
36static inline struct dumb_vga *
37drm_connector_to_dumb_vga(struct drm_connector *connector)
38{
39 return container_of(connector, struct dumb_vga, connector);
40}
41
42static int dumb_vga_get_modes(struct drm_connector *connector)
43{
44 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
45 struct edid *edid;
46 int ret;
47
48 if (IS_ERR(vga->ddc))
49 goto fallback;
50
51 edid = drm_get_edid(connector, vga->ddc);
52 if (!edid) {
53 DRM_INFO("EDID readout failed, falling back to standard modes\n");
54 goto fallback;
55 }
56
57 drm_mode_connector_update_edid_property(connector, edid);
58 return drm_add_edid_modes(connector, edid);
59
60fallback:
61 /*
62 * In case we cannot retrieve the EDIDs (broken or missing i2c
63 * bus), fallback on the XGA standards
64 */
65 ret = drm_add_modes_noedid(connector, 1920, 1200);
66
67 /* And prefer a mode pretty much anyone can handle */
68 drm_set_preferred_mode(connector, 1024, 768);
69
70 return ret;
71}
72
73static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
74 .get_modes = dumb_vga_get_modes,
75};
76
77static enum drm_connector_status
78dumb_vga_connector_detect(struct drm_connector *connector, bool force)
79{
80 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
81
82 /*
83 * Even if we have an I2C bus, we can't assume that the cable
84 * is disconnected if drm_probe_ddc fails. Some cables don't
85 * wire the DDC pins, or the I2C bus might not be working at
86 * all.
87 */
88 if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
89 return connector_status_connected;
90
91 return connector_status_unknown;
92}
93
94static const struct drm_connector_funcs dumb_vga_con_funcs = {
95 .dpms = drm_atomic_helper_connector_dpms,
96 .detect = dumb_vga_connector_detect,
97 .fill_modes = drm_helper_probe_single_connector_modes,
98 .destroy = drm_connector_cleanup,
99 .reset = drm_atomic_helper_connector_reset,
100 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
101 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
102};
103
104static int dumb_vga_attach(struct drm_bridge *bridge)
105{
106 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
107 int ret;
108
109 if (!bridge->encoder) {
110 DRM_ERROR("Missing encoder\n");
111 return -ENODEV;
112 }
113
114 drm_connector_helper_add(&vga->connector,
115 &dumb_vga_con_helper_funcs);
116 ret = drm_connector_init(bridge->dev, &vga->connector,
117 &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
118 if (ret) {
119 DRM_ERROR("Failed to initialize connector\n");
120 return ret;
121 }
122
123 drm_mode_connector_attach_encoder(&vga->connector,
124 bridge->encoder);
125
126 return 0;
127}
128
129static void dumb_vga_enable(struct drm_bridge *bridge)
130{
131 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
132 int ret = 0;
133
134 if (vga->vdd)
135 ret = regulator_enable(vga->vdd);
136
137 if (ret)
138 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
139}
140
141static void dumb_vga_disable(struct drm_bridge *bridge)
142{
143 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
144
145 if (vga->vdd)
146 regulator_disable(vga->vdd);
147}
148
149static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
150 .attach = dumb_vga_attach,
151 .enable = dumb_vga_enable,
152 .disable = dumb_vga_disable,
153};
154
155static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
156{
157 struct device_node *phandle, *remote;
158 struct i2c_adapter *ddc;
159
160 remote = of_graph_get_remote_node(dev->of_node, 1, -1);
161 if (!remote)
162 return ERR_PTR(-EINVAL);
163
164 phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
165 of_node_put(remote);
166 if (!phandle)
167 return ERR_PTR(-ENODEV);
168
169 ddc = of_get_i2c_adapter_by_node(phandle);
170 of_node_put(phandle);
171 if (!ddc)
172 return ERR_PTR(-EPROBE_DEFER);
173
174 return ddc;
175}
176
177static int dumb_vga_probe(struct platform_device *pdev)
178{
179 struct dumb_vga *vga;
180 int ret;
181
182 vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
183 if (!vga)
184 return -ENOMEM;
185 platform_set_drvdata(pdev, vga);
186
187 vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
188 if (IS_ERR(vga->vdd)) {
189 ret = PTR_ERR(vga->vdd);
190 if (ret == -EPROBE_DEFER)
191 return -EPROBE_DEFER;
192 vga->vdd = NULL;
193 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
194 }
195
196 vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
197 if (IS_ERR(vga->ddc)) {
198 if (PTR_ERR(vga->ddc) == -ENODEV) {
199 dev_dbg(&pdev->dev,
200 "No i2c bus specified. Disabling EDID readout\n");
201 } else {
202 dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
203 return PTR_ERR(vga->ddc);
204 }
205 }
206
207 vga->bridge.funcs = &dumb_vga_bridge_funcs;
208 vga->bridge.of_node = pdev->dev.of_node;
209
210 ret = drm_bridge_add(&vga->bridge);
211 if (ret && !IS_ERR(vga->ddc))
212 i2c_put_adapter(vga->ddc);
213
214 return ret;
215}
216
217static 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
229static const struct of_device_id dumb_vga_match[] = {
230 { .compatible = "dumb-vga-dac" },
231 { .compatible = "adi,adv7123" },
232 { .compatible = "ti,ths8135" },
233 {},
234};
235MODULE_DEVICE_TABLE(of, dumb_vga_match);
236
237static struct platform_driver dumb_vga_driver = {
238 .probe = dumb_vga_probe,
239 .remove = dumb_vga_remove,
240 .driver = {
241 .name = "dumb-vga-dac",
242 .of_match_table = dumb_vga_match,
243 },
244};
245module_platform_driver(dumb_vga_driver);
246
247MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
248MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
249MODULE_LICENSE("GPL");