Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  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
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
 * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)

 * Copyright (c) 2017, Collabora Ltd.
 * Copyright (c) 2017, General Electric Company


 * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
 * display bridge of the GE B850v3. There are two physical bridges on the video
 * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
 * physical bridges are automatically configured by the input video signal, and
 * the driver has no access to the video processing pipeline. The driver is
 * only needed to read EDID from the STDP2690 and to handle HPD events from the
 * STDP4028. The driver communicates with both bridges over i2c. The video
 * signal pipeline is as follows:
 *
 *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
 */

#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_edid.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>

#define EDID_EXT_BLOCK_CNT 0x7E

#define STDP4028_IRQ_OUT_CONF_REG 0x02
#define STDP4028_DPTX_IRQ_EN_REG 0x3C
#define STDP4028_DPTX_IRQ_STS_REG 0x3D
#define STDP4028_DPTX_STS_REG 0x3E

#define STDP4028_DPTX_DP_IRQ_EN 0x1000

#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
#define STDP4028_DPTX_IRQ_CONFIG \
		(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)

#define STDP4028_DPTX_HOTPLUG_STS 0x0200
#define STDP4028_DPTX_LINK_STS 0x1000
#define STDP4028_CON_STATE_CONNECTED \
		(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)

#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
#define STDP4028_DPTX_LINK_CH_STS 0x2000
#define STDP4028_DPTX_IRQ_CLEAR \
		(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)

static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);

struct ge_b850v3_lvds {
	struct drm_connector connector;
	struct drm_bridge bridge;
	struct i2c_client *stdp4028_i2c;
	struct i2c_client *stdp2690_i2c;
	struct edid *edid;
};

static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;

static u8 *stdp2690_get_edid(struct i2c_client *client)
{
	struct i2c_adapter *adapter = client->adapter;
	unsigned char start = 0x00;
	unsigned int total_size;
	u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);

	struct i2c_msg msgs[] = {
		{
			.addr	= client->addr,
			.flags	= 0,
			.len	= 1,
			.buf	= &start,
		}, {
			.addr	= client->addr,
			.flags	= I2C_M_RD,
			.len	= EDID_LENGTH,
			.buf	= block,
		}
	};

	if (!block)
		return NULL;

	if (i2c_transfer(adapter, msgs, 2) != 2) {
		DRM_ERROR("Unable to read EDID.\n");
		goto err;
	}

	if (!drm_edid_block_valid(block, 0, false, NULL)) {
		DRM_ERROR("Invalid EDID data\n");
		goto err;
	}

	total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
	if (total_size > EDID_LENGTH) {
		kfree(block);
		block = kmalloc(total_size, GFP_KERNEL);
		if (!block)
			return NULL;

		/* Yes, read the entire buffer, and do not skip the first
		 * EDID_LENGTH bytes.
		 */
		start = 0x00;
		msgs[1].len = total_size;
		msgs[1].buf = block;

		if (i2c_transfer(adapter, msgs, 2) != 2) {
			DRM_ERROR("Unable to read EDID extension blocks.\n");
			goto err;
		}
		if (!drm_edid_block_valid(block, 1, false, NULL)) {
			DRM_ERROR("Invalid EDID data\n");
			goto err;
		}
	}

	return block;

err:
	kfree(block);
	return NULL;
}

static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
{
	struct i2c_client *client;
	int num_modes = 0;

	client = ge_b850v3_lvds_ptr->stdp2690_i2c;

	kfree(ge_b850v3_lvds_ptr->edid);
	ge_b850v3_lvds_ptr->edid = (struct edid *)stdp2690_get_edid(client);

	if (ge_b850v3_lvds_ptr->edid) {
		drm_connector_update_edid_property(connector,
						      ge_b850v3_lvds_ptr->edid);
		num_modes = drm_add_edid_modes(connector,
					       ge_b850v3_lvds_ptr->edid);
	}

	return num_modes;
}

static enum drm_mode_status ge_b850v3_lvds_mode_valid(
		struct drm_connector *connector, struct drm_display_mode *mode)
{
	return MODE_OK;
}

static const struct
drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
	.get_modes = ge_b850v3_lvds_get_modes,
	.mode_valid = ge_b850v3_lvds_mode_valid,
};

static enum drm_connector_status ge_b850v3_lvds_detect(
		struct drm_connector *connector, bool force)
{
	struct i2c_client *stdp4028_i2c =
			ge_b850v3_lvds_ptr->stdp4028_i2c;
	s32 link_state;

	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
					      STDP4028_DPTX_STS_REG);

	if (link_state == STDP4028_CON_STATE_CONNECTED)
		return connector_status_connected;

	if (link_state == 0)
		return connector_status_disconnected;

	return connector_status_unknown;
}

static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
	.fill_modes = drm_helper_probe_single_connector_modes,
	.detect = ge_b850v3_lvds_detect,
	.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 irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
{
	struct i2c_client *stdp4028_i2c
			= ge_b850v3_lvds_ptr->stdp4028_i2c;

	i2c_smbus_write_word_data(stdp4028_i2c,
				  STDP4028_DPTX_IRQ_STS_REG,
				  STDP4028_DPTX_IRQ_CLEAR);

	if (ge_b850v3_lvds_ptr->connector.dev)
		drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->connector.dev);

	return IRQ_HANDLED;
}

static int ge_b850v3_lvds_attach(struct drm_bridge *bridge)
{
	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
	struct i2c_client *stdp4028_i2c
			= ge_b850v3_lvds_ptr->stdp4028_i2c;
	int ret;

	if (!bridge->encoder) {
		DRM_ERROR("Parent encoder object not found");
		return -ENODEV;
	}

	connector->polled = DRM_CONNECTOR_POLL_HPD;

	drm_connector_helper_add(connector,
				 &ge_b850v3_lvds_connector_helper_funcs);

	ret = drm_connector_init(bridge->dev, connector,
				 &ge_b850v3_lvds_connector_funcs,
				 DRM_MODE_CONNECTOR_DisplayPort);
	if (ret) {
		DRM_ERROR("Failed to initialize connector with drm\n");
		return ret;
	}

	ret = drm_connector_attach_encoder(connector, bridge->encoder);
	if (ret)
		return ret;

	/* Configures the bridge to re-enable interrupts after each ack. */
	i2c_smbus_write_word_data(stdp4028_i2c,
				  STDP4028_IRQ_OUT_CONF_REG,
				  STDP4028_DPTX_DP_IRQ_EN);

	/* Enable interrupts */
	i2c_smbus_write_word_data(stdp4028_i2c,
				  STDP4028_DPTX_IRQ_EN_REG,
				  STDP4028_DPTX_IRQ_CONFIG);

	return 0;
}

static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
	.attach = ge_b850v3_lvds_attach,
};

static int ge_b850v3_lvds_init(struct device *dev)
{
	mutex_lock(&ge_b850v3_lvds_dev_mutex);

	if (ge_b850v3_lvds_ptr)
		goto success;

	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
					  sizeof(*ge_b850v3_lvds_ptr),
					  GFP_KERNEL);

	if (!ge_b850v3_lvds_ptr) {
		mutex_unlock(&ge_b850v3_lvds_dev_mutex);
		return -ENOMEM;
	}

success:
	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
	return 0;
}

static void ge_b850v3_lvds_remove(void)
{
	mutex_lock(&ge_b850v3_lvds_dev_mutex);
	/*
	 * This check is to avoid both the drivers
	 * removing the bridge in their remove() function
	 */
	if (!ge_b850v3_lvds_ptr)
		goto out;

	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);

	kfree(ge_b850v3_lvds_ptr->edid);

	ge_b850v3_lvds_ptr = NULL;
out:
	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
}

static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c,
				       const struct i2c_device_id *id)
{
	struct device *dev = &stdp4028_i2c->dev;

	ge_b850v3_lvds_init(dev);

	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);

	/* drm bridge initialization */
	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);

	/* Clear pending interrupts since power up. */
	i2c_smbus_write_word_data(stdp4028_i2c,
				  STDP4028_DPTX_IRQ_STS_REG,
				  STDP4028_DPTX_IRQ_CLEAR);

	if (!stdp4028_i2c->irq)
		return 0;

	return devm_request_threaded_irq(&stdp4028_i2c->dev,
			stdp4028_i2c->irq, NULL,
			ge_b850v3_lvds_irq_handler,
			IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
			"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
}

static int stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
{
	ge_b850v3_lvds_remove();

	return 0;
}

static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
	{"stdp4028_ge_fw", 0},
	{},
};
MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);

static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
	{},
};
MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);

static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
	.id_table	= stdp4028_ge_b850v3_fw_i2c_table,
	.probe		= stdp4028_ge_b850v3_fw_probe,
	.remove		= stdp4028_ge_b850v3_fw_remove,
	.driver		= {
		.name		= "stdp4028-ge-b850v3-fw",
		.of_match_table = stdp4028_ge_b850v3_fw_match,
	},
};

static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c,
				       const struct i2c_device_id *id)
{
	struct device *dev = &stdp2690_i2c->dev;

	ge_b850v3_lvds_init(dev);

	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);

	return 0;
}

static int stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
{
	ge_b850v3_lvds_remove();

	return 0;
}

static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
	{"stdp2690_ge_fw", 0},
	{},
};
MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);

static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
	{},
};
MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);

static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
	.id_table	= stdp2690_ge_b850v3_fw_i2c_table,
	.probe		= stdp2690_ge_b850v3_fw_probe,
	.remove		= stdp2690_ge_b850v3_fw_remove,
	.driver		= {
		.name		= "stdp2690-ge-b850v3-fw",
		.of_match_table = stdp2690_ge_b850v3_fw_match,
	},
};

static int __init stdpxxxx_ge_b850v3_init(void)
{
	int ret;

	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
	if (ret)
		return ret;

	return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
}
module_init(stdpxxxx_ge_b850v3_init);

static void __exit stdpxxxx_ge_b850v3_exit(void)
{
	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
}
module_exit(stdpxxxx_ge_b850v3_exit);

MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
MODULE_LICENSE("GPL v2");