summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/bridge/dumb-vga-dac.c
blob: e64736c39a9ffb4ea9e54289368cde0091dc7adf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
/*
 * Copyright (C) 2015-2016 Free Electrons
 * Copyright (C) 2015-2016 NextThing Co
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/of_graph.h>
#include <linux/regulator/consumer.h>

#include <drm/drmP.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drm_probe_helper.h>

struct dumb_vga {
	struct drm_bridge	bridge;
	struct drm_connector	connector;

	struct i2c_adapter	*ddc;
	struct regulator	*vdd;
};

static inline struct dumb_vga *
drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
{
	return container_of(bridge, struct dumb_vga, bridge);
}

static inline struct dumb_vga *
drm_connector_to_dumb_vga(struct drm_connector *connector)
{
	return container_of(connector, struct dumb_vga, connector);
}

static int dumb_vga_get_modes(struct drm_connector *connector)
{
	struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
	struct edid *edid;
	int ret;

	if (IS_ERR(vga->ddc))
		goto fallback;

	edid = drm_get_edid(connector, vga->ddc);
	if (!edid) {
		DRM_INFO("EDID readout failed, falling back to standard modes\n");
		goto fallback;
	}

	drm_connector_update_edid_property(connector, edid);
	ret = drm_add_edid_modes(connector, edid);
	kfree(edid);
	return ret;

fallback:
	/*
	 * In case we cannot retrieve the EDIDs (broken or missing i2c
	 * bus), fallback on the XGA standards
	 */
	ret = drm_add_modes_noedid(connector, 1920, 1200);

	/* And prefer a mode pretty much anyone can handle */
	drm_set_preferred_mode(connector, 1024, 768);

	return ret;
}

static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
	.get_modes	= dumb_vga_get_modes,
};

static enum drm_connector_status
dumb_vga_connector_detect(struct drm_connector *connector, bool force)
{
	struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);

	/*
	 * Even if we have an I2C bus, we can't assume that the cable
	 * is disconnected if drm_probe_ddc fails. Some cables don't
	 * wire the DDC pins, or the I2C bus might not be working at
	 * all.
	 */
	if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
		return connector_status_connected;

	return connector_status_unknown;
}

static const struct drm_connector_funcs dumb_vga_con_funcs = {
	.detect			= dumb_vga_connector_detect,
	.fill_modes		= drm_helper_probe_single_connector_modes,
	.destroy		= drm_connector_cleanup,
	.reset			= drm_atomic_helper_connector_reset,
	.atomic_duplicate_state	= drm_atomic_helper_connector_duplicate_state,
	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
};

static int dumb_vga_attach(struct drm_bridge *bridge)
{
	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
	int ret;

	if (!bridge->encoder) {
		DRM_ERROR("Missing encoder\n");
		return -ENODEV;
	}

	drm_connector_helper_add(&vga->connector,
				 &dumb_vga_con_helper_funcs);
	ret = drm_connector_init(bridge->dev, &vga->connector,
				 &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
	if (ret) {
		DRM_ERROR("Failed to initialize connector\n");
		return ret;
	}

	drm_connector_attach_encoder(&vga->connector,
					  bridge->encoder);

	return 0;
}

static void dumb_vga_enable(struct drm_bridge *bridge)
{
	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
	int ret = 0;

	if (vga->vdd)
		ret = regulator_enable(vga->vdd);

	if (ret)
		DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
}

static void dumb_vga_disable(struct drm_bridge *bridge)
{
	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);

	if (vga->vdd)
		regulator_disable(vga->vdd);
}

static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
	.attach		= dumb_vga_attach,
	.enable		= dumb_vga_enable,
	.disable	= dumb_vga_disable,
};

static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
{
	struct device_node *phandle, *remote;
	struct i2c_adapter *ddc;

	remote = of_graph_get_remote_node(dev->of_node, 1, -1);
	if (!remote)
		return ERR_PTR(-EINVAL);

	phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
	of_node_put(remote);
	if (!phandle)
		return ERR_PTR(-ENODEV);

	ddc = of_get_i2c_adapter_by_node(phandle);
	of_node_put(phandle);
	if (!ddc)
		return ERR_PTR(-EPROBE_DEFER);

	return ddc;
}

static int dumb_vga_probe(struct platform_device *pdev)
{
	struct dumb_vga *vga;

	vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
	if (!vga)
		return -ENOMEM;
	platform_set_drvdata(pdev, vga);

	vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
	if (IS_ERR(vga->vdd)) {
		int ret = PTR_ERR(vga->vdd);
		if (ret == -EPROBE_DEFER)
			return -EPROBE_DEFER;
		vga->vdd = NULL;
		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
	}

	vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
	if (IS_ERR(vga->ddc)) {
		if (PTR_ERR(vga->ddc) == -ENODEV) {
			dev_dbg(&pdev->dev,
				"No i2c bus specified. Disabling EDID readout\n");
		} else {
			dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
			return PTR_ERR(vga->ddc);
		}
	}

	vga->bridge.funcs = &dumb_vga_bridge_funcs;
	vga->bridge.of_node = pdev->dev.of_node;
	vga->bridge.timings = of_device_get_match_data(&pdev->dev);

	drm_bridge_add(&vga->bridge);

	return 0;
}

static int dumb_vga_remove(struct platform_device *pdev)
{
	struct dumb_vga *vga = platform_get_drvdata(pdev);

	drm_bridge_remove(&vga->bridge);

	if (!IS_ERR(vga->ddc))
		i2c_put_adapter(vga->ddc);

	return 0;
}

/*
 * We assume the ADV7123 DAC is the "default" for historical reasons
 * Information taken from the ADV7123 datasheet, revision D.
 * NOTE: the ADV7123EP seems to have other timings and need a new timings
 * set if used.
 */
static const struct drm_bridge_timings default_dac_timings = {
	/* Timing specifications, datasheet page 7 */
	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
	.setup_time_ps = 500,
	.hold_time_ps = 1500,
};

/*
 * Information taken from the THS8134, THS8134A, THS8134B datasheet named
 * "SLVS205D", dated May 1990, revised March 2000.
 */
static const struct drm_bridge_timings ti_ths8134_dac_timings = {
	/* From timing diagram, datasheet page 9 */
	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
	/* From datasheet, page 12 */
	.setup_time_ps = 3000,
	/* I guess this means latched input */
	.hold_time_ps = 0,
};

/*
 * Information taken from the THS8135 datasheet named "SLAS343B", dated
 * May 2001, revised April 2013.
 */
static const struct drm_bridge_timings ti_ths8135_dac_timings = {
	/* From timing diagram, datasheet page 14 */
	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
	/* From datasheet, page 16 */
	.setup_time_ps = 2000,
	.hold_time_ps = 500,
};

static const struct of_device_id dumb_vga_match[] = {
	{
		.compatible = "dumb-vga-dac",
		.data = NULL,
	},
	{
		.compatible = "adi,adv7123",
		.data = &default_dac_timings,
	},
	{
		.compatible = "ti,ths8135",
		.data = &ti_ths8135_dac_timings,
	},
	{
		.compatible = "ti,ths8134",
		.data = &ti_ths8134_dac_timings,
	},
	{},
};
MODULE_DEVICE_TABLE(of, dumb_vga_match);

static struct platform_driver dumb_vga_driver = {
	.probe	= dumb_vga_probe,
	.remove	= dumb_vga_remove,
	.driver		= {
		.name		= "dumb-vga-dac",
		.of_match_table	= dumb_vga_match,
	},
};
module_platform_driver(dumb_vga_driver);

MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
MODULE_LICENSE("GPL");