2 * Copyright (C) 2015-2016 Free Electrons
3 * Copyright (C) 2015-2016 NextThing Co
5 * Maxime Ripard <maxime.ripard@free-electrons.com>
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.
13 #include <linux/module.h>
14 #include <linux/of_graph.h>
15 #include <linux/regulator/consumer.h>
18 #include <drm/drm_atomic_helper.h>
19 #include <drm/drm_crtc.h>
20 #include <drm/drm_crtc_helper.h>
23 struct drm_bridge bridge;
24 struct drm_connector connector;
26 struct i2c_adapter *ddc;
27 struct regulator *vdd;
30 static inline struct dumb_vga *
31 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
33 return container_of(bridge, struct dumb_vga, bridge);
36 static inline struct dumb_vga *
37 drm_connector_to_dumb_vga(struct drm_connector *connector)
39 return container_of(connector, struct dumb_vga, connector);
42 static int dumb_vga_get_modes(struct drm_connector *connector)
44 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
51 edid = drm_get_edid(connector, vga->ddc);
53 DRM_INFO("EDID readout failed, falling back to standard modes\n");
57 drm_mode_connector_update_edid_property(connector, edid);
58 return drm_add_edid_modes(connector, edid);
62 * In case we cannot retrieve the EDIDs (broken or missing i2c
63 * bus), fallback on the XGA standards
65 ret = drm_add_modes_noedid(connector, 1920, 1200);
67 /* And prefer a mode pretty much anyone can handle */
68 drm_set_preferred_mode(connector, 1024, 768);
73 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
74 .get_modes = dumb_vga_get_modes,
77 static enum drm_connector_status
78 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
80 struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
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
88 if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
89 return connector_status_connected;
91 return connector_status_unknown;
94 static 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,
104 static int dumb_vga_attach(struct drm_bridge *bridge)
106 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
109 if (!bridge->encoder) {
110 DRM_ERROR("Missing encoder\n");
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);
119 DRM_ERROR("Failed to initialize connector\n");
123 drm_mode_connector_attach_encoder(&vga->connector,
129 static void dumb_vga_enable(struct drm_bridge *bridge)
131 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
135 ret = regulator_enable(vga->vdd);
138 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
141 static void dumb_vga_disable(struct drm_bridge *bridge)
143 struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
146 regulator_disable(vga->vdd);
149 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
150 .attach = dumb_vga_attach,
151 .enable = dumb_vga_enable,
152 .disable = dumb_vga_disable,
155 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
157 struct device_node *end_node, *phandle, *remote;
158 struct i2c_adapter *ddc;
160 end_node = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
162 dev_err(dev, "Missing connector endpoint\n");
163 return ERR_PTR(-ENODEV);
166 remote = of_graph_get_remote_port_parent(end_node);
167 of_node_put(end_node);
169 dev_err(dev, "Enable to parse remote node\n");
170 return ERR_PTR(-EINVAL);
173 phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
176 return ERR_PTR(-ENODEV);
178 ddc = of_get_i2c_adapter_by_node(phandle);
179 of_node_put(phandle);
181 return ERR_PTR(-EPROBE_DEFER);
186 static int dumb_vga_probe(struct platform_device *pdev)
188 struct dumb_vga *vga;
191 vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
194 platform_set_drvdata(pdev, vga);
196 vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
197 if (IS_ERR(vga->vdd)) {
198 ret = PTR_ERR(vga->vdd);
199 if (ret == -EPROBE_DEFER)
200 return -EPROBE_DEFER;
202 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
205 vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
206 if (IS_ERR(vga->ddc)) {
207 if (PTR_ERR(vga->ddc) == -ENODEV) {
209 "No i2c bus specified. Disabling EDID readout\n");
211 dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
212 return PTR_ERR(vga->ddc);
216 vga->bridge.funcs = &dumb_vga_bridge_funcs;
217 vga->bridge.of_node = pdev->dev.of_node;
219 ret = drm_bridge_add(&vga->bridge);
220 if (ret && !IS_ERR(vga->ddc))
221 i2c_put_adapter(vga->ddc);
226 static int dumb_vga_remove(struct platform_device *pdev)
228 struct dumb_vga *vga = platform_get_drvdata(pdev);
230 drm_bridge_remove(&vga->bridge);
232 if (!IS_ERR(vga->ddc))
233 i2c_put_adapter(vga->ddc);
238 static const struct of_device_id dumb_vga_match[] = {
239 { .compatible = "dumb-vga-dac" },
240 { .compatible = "ti,ths8135" },
243 MODULE_DEVICE_TABLE(of, dumb_vga_match);
245 static struct platform_driver dumb_vga_driver = {
246 .probe = dumb_vga_probe,
247 .remove = dumb_vga_remove,
249 .name = "dumb-vga-dac",
250 .of_match_table = dumb_vga_match,
253 module_platform_driver(dumb_vga_driver);
255 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
256 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
257 MODULE_LICENSE("GPL");