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 *end_node, *phandle, *remote;
158	struct i2c_adapter *ddc;
159
160	end_node = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
161	if (!end_node) {
162		dev_err(dev, "Missing connector endpoint\n");
163		return ERR_PTR(-ENODEV);
164	}
165
166	remote = of_graph_get_remote_port_parent(end_node);
167	of_node_put(end_node);
168	if (!remote) {
169		dev_err(dev, "Enable to parse remote node\n");
170		return ERR_PTR(-EINVAL);
171	}
172
173	phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
174	of_node_put(remote);
175	if (!phandle)
176		return ERR_PTR(-ENODEV);
177
178	ddc = of_get_i2c_adapter_by_node(phandle);
179	of_node_put(phandle);
180	if (!ddc)
181		return ERR_PTR(-EPROBE_DEFER);
182
183	return ddc;
184}
185
186static int dumb_vga_probe(struct platform_device *pdev)
187{
188	struct dumb_vga *vga;
189	int ret;
190
191	vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
192	if (!vga)
193		return -ENOMEM;
194	platform_set_drvdata(pdev, vga);
195
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;
201		vga->vdd = NULL;
202		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
203	}
204
205	vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
206	if (IS_ERR(vga->ddc)) {
207		if (PTR_ERR(vga->ddc) == -ENODEV) {
208			dev_dbg(&pdev->dev,
209				"No i2c bus specified. Disabling EDID readout\n");
210		} else {
211			dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
212			return PTR_ERR(vga->ddc);
213		}
214	}
215
216	vga->bridge.funcs = &dumb_vga_bridge_funcs;
217	vga->bridge.of_node = pdev->dev.of_node;
218
219	ret = drm_bridge_add(&vga->bridge);
220	if (ret && !IS_ERR(vga->ddc))
221		i2c_put_adapter(vga->ddc);
222
223	return ret;
224}
225
226static int dumb_vga_remove(struct platform_device *pdev)
227{
228	struct dumb_vga *vga = platform_get_drvdata(pdev);
229
230	drm_bridge_remove(&vga->bridge);
231
232	if (!IS_ERR(vga->ddc))
233		i2c_put_adapter(vga->ddc);
234
235	return 0;
236}
237
238static const struct of_device_id dumb_vga_match[] = {
239	{ .compatible = "dumb-vga-dac" },
240	{},
241};
242MODULE_DEVICE_TABLE(of, dumb_vga_match);
243
244static struct platform_driver dumb_vga_driver = {
245	.probe	= dumb_vga_probe,
246	.remove	= dumb_vga_remove,
247	.driver		= {
248		.name		= "dumb-vga-dac",
249		.of_match_table	= dumb_vga_match,
250	},
251};
252module_platform_driver(dumb_vga_driver);
253
254MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
255MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
256MODULE_LICENSE("GPL");