1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
4  * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)
5 
6  * Copyright (c) 2017, Collabora Ltd.
7  * Copyright (c) 2017, General Electric Company
8 
9 
10  * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
11  * display bridge of the GE B850v3. There are two physical bridges on the video
12  * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
13  * physical bridges are automatically configured by the input video signal, and
14  * the driver has no access to the video processing pipeline. The driver is
15  * only needed to read EDID from the STDP2690 and to handle HPD events from the
16  * STDP4028. The driver communicates with both bridges over i2c. The video
17  * signal pipeline is as follows:
18  *
19  *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
20  */
21 
22 #include <linux/i2c.h>
23 #include <linux/module.h>
24 #include <linux/of.h>
25 
26 #include <drm/drm_atomic.h>
27 #include <drm/drm_atomic_helper.h>
28 #include <drm/drm_bridge.h>
29 #include <drm/drm_edid.h>
30 #include <drm/drm_print.h>
31 #include <drm/drm_probe_helper.h>
32 
33 #define EDID_EXT_BLOCK_CNT 0x7E
34 
35 #define STDP4028_IRQ_OUT_CONF_REG 0x02
36 #define STDP4028_DPTX_IRQ_EN_REG 0x3C
37 #define STDP4028_DPTX_IRQ_STS_REG 0x3D
38 #define STDP4028_DPTX_STS_REG 0x3E
39 
40 #define STDP4028_DPTX_DP_IRQ_EN 0x1000
41 
42 #define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
43 #define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
44 #define STDP4028_DPTX_IRQ_CONFIG \
45 		(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)
46 
47 #define STDP4028_DPTX_HOTPLUG_STS 0x0200
48 #define STDP4028_DPTX_LINK_STS 0x1000
49 #define STDP4028_CON_STATE_CONNECTED \
50 		(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)
51 
52 #define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
53 #define STDP4028_DPTX_LINK_CH_STS 0x2000
54 #define STDP4028_DPTX_IRQ_CLEAR \
55 		(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)
56 
57 static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);
58 
59 struct ge_b850v3_lvds {
60 	struct drm_connector connector;
61 	struct drm_bridge bridge;
62 	struct i2c_client *stdp4028_i2c;
63 	struct i2c_client *stdp2690_i2c;
64 };
65 
66 static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;
67 
stdp2690_get_edid(struct i2c_client * client)68 static u8 *stdp2690_get_edid(struct i2c_client *client)
69 {
70 	struct i2c_adapter *adapter = client->adapter;
71 	unsigned char start = 0x00;
72 	unsigned int total_size;
73 	u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);
74 
75 	struct i2c_msg msgs[] = {
76 		{
77 			.addr	= client->addr,
78 			.flags	= 0,
79 			.len	= 1,
80 			.buf	= &start,
81 		}, {
82 			.addr	= client->addr,
83 			.flags	= I2C_M_RD,
84 			.len	= EDID_LENGTH,
85 			.buf	= block,
86 		}
87 	};
88 
89 	if (!block)
90 		return NULL;
91 
92 	if (i2c_transfer(adapter, msgs, 2) != 2) {
93 		DRM_ERROR("Unable to read EDID.\n");
94 		goto err;
95 	}
96 
97 	if (!drm_edid_block_valid(block, 0, false, NULL)) {
98 		DRM_ERROR("Invalid EDID data\n");
99 		goto err;
100 	}
101 
102 	total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
103 	if (total_size > EDID_LENGTH) {
104 		kfree(block);
105 		block = kmalloc(total_size, GFP_KERNEL);
106 		if (!block)
107 			return NULL;
108 
109 		/* Yes, read the entire buffer, and do not skip the first
110 		 * EDID_LENGTH bytes.
111 		 */
112 		start = 0x00;
113 		msgs[1].len = total_size;
114 		msgs[1].buf = block;
115 
116 		if (i2c_transfer(adapter, msgs, 2) != 2) {
117 			DRM_ERROR("Unable to read EDID extension blocks.\n");
118 			goto err;
119 		}
120 		if (!drm_edid_block_valid(block, 1, false, NULL)) {
121 			DRM_ERROR("Invalid EDID data\n");
122 			goto err;
123 		}
124 	}
125 
126 	return block;
127 
128 err:
129 	kfree(block);
130 	return NULL;
131 }
132 
ge_b850v3_lvds_get_edid(struct drm_bridge * bridge,struct drm_connector * connector)133 static struct edid *ge_b850v3_lvds_get_edid(struct drm_bridge *bridge,
134 					    struct drm_connector *connector)
135 {
136 	struct i2c_client *client;
137 
138 	client = ge_b850v3_lvds_ptr->stdp2690_i2c;
139 
140 	return (struct edid *)stdp2690_get_edid(client);
141 }
142 
ge_b850v3_lvds_get_modes(struct drm_connector * connector)143 static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
144 {
145 	struct edid *edid;
146 	int num_modes;
147 
148 	edid = ge_b850v3_lvds_get_edid(&ge_b850v3_lvds_ptr->bridge, connector);
149 
150 	drm_connector_update_edid_property(connector, edid);
151 	num_modes = drm_add_edid_modes(connector, edid);
152 	kfree(edid);
153 
154 	return num_modes;
155 }
156 
ge_b850v3_lvds_mode_valid(struct drm_connector * connector,struct drm_display_mode * mode)157 static enum drm_mode_status ge_b850v3_lvds_mode_valid(
158 		struct drm_connector *connector, struct drm_display_mode *mode)
159 {
160 	return MODE_OK;
161 }
162 
163 static const struct
164 drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
165 	.get_modes = ge_b850v3_lvds_get_modes,
166 	.mode_valid = ge_b850v3_lvds_mode_valid,
167 };
168 
ge_b850v3_lvds_bridge_detect(struct drm_bridge * bridge)169 static enum drm_connector_status ge_b850v3_lvds_bridge_detect(struct drm_bridge *bridge)
170 {
171 	struct i2c_client *stdp4028_i2c =
172 			ge_b850v3_lvds_ptr->stdp4028_i2c;
173 	s32 link_state;
174 
175 	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
176 					      STDP4028_DPTX_STS_REG);
177 
178 	if (link_state == STDP4028_CON_STATE_CONNECTED)
179 		return connector_status_connected;
180 
181 	if (link_state == 0)
182 		return connector_status_disconnected;
183 
184 	return connector_status_unknown;
185 }
186 
ge_b850v3_lvds_detect(struct drm_connector * connector,bool force)187 static enum drm_connector_status ge_b850v3_lvds_detect(struct drm_connector *connector,
188 						       bool force)
189 {
190 	return ge_b850v3_lvds_bridge_detect(&ge_b850v3_lvds_ptr->bridge);
191 }
192 
193 static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
194 	.fill_modes = drm_helper_probe_single_connector_modes,
195 	.detect = ge_b850v3_lvds_detect,
196 	.destroy = drm_connector_cleanup,
197 	.reset = drm_atomic_helper_connector_reset,
198 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
199 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
200 };
201 
ge_b850v3_lvds_create_connector(struct drm_bridge * bridge)202 static int ge_b850v3_lvds_create_connector(struct drm_bridge *bridge)
203 {
204 	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
205 	int ret;
206 
207 	if (!bridge->encoder) {
208 		DRM_ERROR("Parent encoder object not found");
209 		return -ENODEV;
210 	}
211 
212 	connector->polled = DRM_CONNECTOR_POLL_HPD;
213 
214 	drm_connector_helper_add(connector,
215 				 &ge_b850v3_lvds_connector_helper_funcs);
216 
217 	ret = drm_connector_init(bridge->dev, connector,
218 				 &ge_b850v3_lvds_connector_funcs,
219 				 DRM_MODE_CONNECTOR_DisplayPort);
220 	if (ret) {
221 		DRM_ERROR("Failed to initialize connector with drm\n");
222 		return ret;
223 	}
224 
225 	return drm_connector_attach_encoder(connector, bridge->encoder);
226 }
227 
ge_b850v3_lvds_irq_handler(int irq,void * dev_id)228 static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
229 {
230 	struct i2c_client *stdp4028_i2c
231 			= ge_b850v3_lvds_ptr->stdp4028_i2c;
232 
233 	i2c_smbus_write_word_data(stdp4028_i2c,
234 				  STDP4028_DPTX_IRQ_STS_REG,
235 				  STDP4028_DPTX_IRQ_CLEAR);
236 
237 	if (ge_b850v3_lvds_ptr->bridge.dev)
238 		drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->bridge.dev);
239 
240 	return IRQ_HANDLED;
241 }
242 
ge_b850v3_lvds_attach(struct drm_bridge * bridge,enum drm_bridge_attach_flags flags)243 static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
244 				 enum drm_bridge_attach_flags flags)
245 {
246 	struct i2c_client *stdp4028_i2c
247 			= ge_b850v3_lvds_ptr->stdp4028_i2c;
248 
249 	/* Configures the bridge to re-enable interrupts after each ack. */
250 	i2c_smbus_write_word_data(stdp4028_i2c,
251 				  STDP4028_IRQ_OUT_CONF_REG,
252 				  STDP4028_DPTX_DP_IRQ_EN);
253 
254 	/* Enable interrupts */
255 	i2c_smbus_write_word_data(stdp4028_i2c,
256 				  STDP4028_DPTX_IRQ_EN_REG,
257 				  STDP4028_DPTX_IRQ_CONFIG);
258 
259 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
260 		return 0;
261 
262 	return ge_b850v3_lvds_create_connector(bridge);
263 }
264 
265 static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
266 	.attach = ge_b850v3_lvds_attach,
267 	.detect = ge_b850v3_lvds_bridge_detect,
268 	.get_edid = ge_b850v3_lvds_get_edid,
269 };
270 
ge_b850v3_lvds_init(struct device * dev)271 static int ge_b850v3_lvds_init(struct device *dev)
272 {
273 	mutex_lock(&ge_b850v3_lvds_dev_mutex);
274 
275 	if (ge_b850v3_lvds_ptr)
276 		goto success;
277 
278 	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
279 					  sizeof(*ge_b850v3_lvds_ptr),
280 					  GFP_KERNEL);
281 
282 	if (!ge_b850v3_lvds_ptr) {
283 		mutex_unlock(&ge_b850v3_lvds_dev_mutex);
284 		return -ENOMEM;
285 	}
286 
287 success:
288 	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
289 	return 0;
290 }
291 
ge_b850v3_lvds_remove(void)292 static void ge_b850v3_lvds_remove(void)
293 {
294 	mutex_lock(&ge_b850v3_lvds_dev_mutex);
295 	/*
296 	 * This check is to avoid both the drivers
297 	 * removing the bridge in their remove() function
298 	 */
299 	if (!ge_b850v3_lvds_ptr ||
300 	    !ge_b850v3_lvds_ptr->stdp2690_i2c ||
301 		!ge_b850v3_lvds_ptr->stdp4028_i2c)
302 		goto out;
303 
304 	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
305 
306 	ge_b850v3_lvds_ptr = NULL;
307 out:
308 	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
309 }
310 
ge_b850v3_register(void)311 static int ge_b850v3_register(void)
312 {
313 	struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c;
314 	struct device *dev = &stdp4028_i2c->dev;
315 
316 	/* drm bridge initialization */
317 	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
318 	ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT |
319 					 DRM_BRIDGE_OP_EDID;
320 	ge_b850v3_lvds_ptr->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
321 	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
322 	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);
323 
324 	/* Clear pending interrupts since power up. */
325 	i2c_smbus_write_word_data(stdp4028_i2c,
326 				  STDP4028_DPTX_IRQ_STS_REG,
327 				  STDP4028_DPTX_IRQ_CLEAR);
328 
329 	if (!stdp4028_i2c->irq)
330 		return 0;
331 
332 	return devm_request_threaded_irq(&stdp4028_i2c->dev,
333 			stdp4028_i2c->irq, NULL,
334 			ge_b850v3_lvds_irq_handler,
335 			IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
336 			"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
337 }
338 
stdp4028_ge_b850v3_fw_probe(struct i2c_client * stdp4028_i2c)339 static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c)
340 {
341 	struct device *dev = &stdp4028_i2c->dev;
342 	int ret;
343 
344 	ret = ge_b850v3_lvds_init(dev);
345 
346 	if (ret)
347 		return ret;
348 
349 	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
350 	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
351 
352 	/* Only register after both bridges are probed */
353 	if (!ge_b850v3_lvds_ptr->stdp2690_i2c)
354 		return 0;
355 
356 	return ge_b850v3_register();
357 }
358 
stdp4028_ge_b850v3_fw_remove(struct i2c_client * stdp4028_i2c)359 static void stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
360 {
361 	ge_b850v3_lvds_remove();
362 }
363 
364 static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
365 	{"stdp4028_ge_fw", 0},
366 	{},
367 };
368 MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);
369 
370 static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
371 	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
372 	{},
373 };
374 MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);
375 
376 static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
377 	.id_table	= stdp4028_ge_b850v3_fw_i2c_table,
378 	.probe		= stdp4028_ge_b850v3_fw_probe,
379 	.remove		= stdp4028_ge_b850v3_fw_remove,
380 	.driver		= {
381 		.name		= "stdp4028-ge-b850v3-fw",
382 		.of_match_table = stdp4028_ge_b850v3_fw_match,
383 	},
384 };
385 
stdp2690_ge_b850v3_fw_probe(struct i2c_client * stdp2690_i2c)386 static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c)
387 {
388 	struct device *dev = &stdp2690_i2c->dev;
389 	int ret;
390 
391 	ret = ge_b850v3_lvds_init(dev);
392 
393 	if (ret)
394 		return ret;
395 
396 	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
397 	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
398 
399 	/* Only register after both bridges are probed */
400 	if (!ge_b850v3_lvds_ptr->stdp4028_i2c)
401 		return 0;
402 
403 	return ge_b850v3_register();
404 }
405 
stdp2690_ge_b850v3_fw_remove(struct i2c_client * stdp2690_i2c)406 static void stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
407 {
408 	ge_b850v3_lvds_remove();
409 }
410 
411 static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
412 	{"stdp2690_ge_fw", 0},
413 	{},
414 };
415 MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);
416 
417 static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
418 	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
419 	{},
420 };
421 MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);
422 
423 static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
424 	.id_table	= stdp2690_ge_b850v3_fw_i2c_table,
425 	.probe		= stdp2690_ge_b850v3_fw_probe,
426 	.remove		= stdp2690_ge_b850v3_fw_remove,
427 	.driver		= {
428 		.name		= "stdp2690-ge-b850v3-fw",
429 		.of_match_table = stdp2690_ge_b850v3_fw_match,
430 	},
431 };
432 
stdpxxxx_ge_b850v3_init(void)433 static int __init stdpxxxx_ge_b850v3_init(void)
434 {
435 	int ret;
436 
437 	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
438 	if (ret)
439 		return ret;
440 
441 	ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
442 	if (ret)
443 		i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
444 
445 	return ret;
446 }
447 module_init(stdpxxxx_ge_b850v3_init);
448 
stdpxxxx_ge_b850v3_exit(void)449 static void __exit stdpxxxx_ge_b850v3_exit(void)
450 {
451 	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
452 	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
453 }
454 module_exit(stdpxxxx_ge_b850v3_exit);
455 
456 MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
457 MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
458 MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
459 MODULE_LICENSE("GPL v2");
460