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