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_read_block(void * context,u8 * buf,unsigned int block,size_t len)68 static int stdp2690_read_block(void *context, u8 *buf, unsigned int block, size_t len)
69 {
70 struct i2c_client *client = context;
71 struct i2c_adapter *adapter = client->adapter;
72 unsigned char start = block * EDID_LENGTH;
73
74 struct i2c_msg msgs[] = {
75 {
76 .addr = client->addr,
77 .flags = 0,
78 .len = 1,
79 .buf = &start,
80 }, {
81 .addr = client->addr,
82 .flags = I2C_M_RD,
83 .len = len,
84 .buf = buf,
85 }
86 };
87
88 if (i2c_transfer(adapter, msgs, 2) != 2)
89 return -1;
90
91 return 0;
92 }
93
ge_b850v3_lvds_edid_read(struct drm_bridge * bridge,struct drm_connector * connector)94 static const struct drm_edid *ge_b850v3_lvds_edid_read(struct drm_bridge *bridge,
95 struct drm_connector *connector)
96 {
97 struct i2c_client *client;
98
99 client = ge_b850v3_lvds_ptr->stdp2690_i2c;
100
101 return drm_edid_read_custom(connector, stdp2690_read_block, client);
102 }
103
ge_b850v3_lvds_get_modes(struct drm_connector * connector)104 static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
105 {
106 const struct drm_edid *drm_edid;
107 int num_modes;
108
109 drm_edid = ge_b850v3_lvds_edid_read(&ge_b850v3_lvds_ptr->bridge, connector);
110
111 drm_edid_connector_update(connector, drm_edid);
112 num_modes = drm_edid_connector_add_modes(connector);
113 drm_edid_free(drm_edid);
114
115 return num_modes;
116 }
117
ge_b850v3_lvds_mode_valid(struct drm_connector * connector,struct drm_display_mode * mode)118 static enum drm_mode_status ge_b850v3_lvds_mode_valid(
119 struct drm_connector *connector, struct drm_display_mode *mode)
120 {
121 return MODE_OK;
122 }
123
124 static const struct
125 drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
126 .get_modes = ge_b850v3_lvds_get_modes,
127 .mode_valid = ge_b850v3_lvds_mode_valid,
128 };
129
ge_b850v3_lvds_bridge_detect(struct drm_bridge * bridge)130 static enum drm_connector_status ge_b850v3_lvds_bridge_detect(struct drm_bridge *bridge)
131 {
132 struct i2c_client *stdp4028_i2c =
133 ge_b850v3_lvds_ptr->stdp4028_i2c;
134 s32 link_state;
135
136 link_state = i2c_smbus_read_word_data(stdp4028_i2c,
137 STDP4028_DPTX_STS_REG);
138
139 if (link_state == STDP4028_CON_STATE_CONNECTED)
140 return connector_status_connected;
141
142 if (link_state == 0)
143 return connector_status_disconnected;
144
145 return connector_status_unknown;
146 }
147
ge_b850v3_lvds_detect(struct drm_connector * connector,bool force)148 static enum drm_connector_status ge_b850v3_lvds_detect(struct drm_connector *connector,
149 bool force)
150 {
151 return ge_b850v3_lvds_bridge_detect(&ge_b850v3_lvds_ptr->bridge);
152 }
153
154 static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
155 .fill_modes = drm_helper_probe_single_connector_modes,
156 .detect = ge_b850v3_lvds_detect,
157 .destroy = drm_connector_cleanup,
158 .reset = drm_atomic_helper_connector_reset,
159 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
160 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
161 };
162
ge_b850v3_lvds_create_connector(struct drm_bridge * bridge)163 static int ge_b850v3_lvds_create_connector(struct drm_bridge *bridge)
164 {
165 struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
166 int ret;
167
168 connector->polled = DRM_CONNECTOR_POLL_HPD;
169
170 drm_connector_helper_add(connector,
171 &ge_b850v3_lvds_connector_helper_funcs);
172
173 ret = drm_connector_init(bridge->dev, connector,
174 &ge_b850v3_lvds_connector_funcs,
175 DRM_MODE_CONNECTOR_DisplayPort);
176 if (ret) {
177 DRM_ERROR("Failed to initialize connector with drm\n");
178 return ret;
179 }
180
181 return drm_connector_attach_encoder(connector, bridge->encoder);
182 }
183
ge_b850v3_lvds_irq_handler(int irq,void * dev_id)184 static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
185 {
186 struct i2c_client *stdp4028_i2c
187 = ge_b850v3_lvds_ptr->stdp4028_i2c;
188
189 i2c_smbus_write_word_data(stdp4028_i2c,
190 STDP4028_DPTX_IRQ_STS_REG,
191 STDP4028_DPTX_IRQ_CLEAR);
192
193 if (ge_b850v3_lvds_ptr->bridge.dev)
194 drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->bridge.dev);
195
196 return IRQ_HANDLED;
197 }
198
ge_b850v3_lvds_attach(struct drm_bridge * bridge,enum drm_bridge_attach_flags flags)199 static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
200 enum drm_bridge_attach_flags flags)
201 {
202 struct i2c_client *stdp4028_i2c
203 = ge_b850v3_lvds_ptr->stdp4028_i2c;
204
205 /* Configures the bridge to re-enable interrupts after each ack. */
206 i2c_smbus_write_word_data(stdp4028_i2c,
207 STDP4028_IRQ_OUT_CONF_REG,
208 STDP4028_DPTX_DP_IRQ_EN);
209
210 /* Enable interrupts */
211 i2c_smbus_write_word_data(stdp4028_i2c,
212 STDP4028_DPTX_IRQ_EN_REG,
213 STDP4028_DPTX_IRQ_CONFIG);
214
215 if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
216 return 0;
217
218 return ge_b850v3_lvds_create_connector(bridge);
219 }
220
221 static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
222 .attach = ge_b850v3_lvds_attach,
223 .detect = ge_b850v3_lvds_bridge_detect,
224 .edid_read = ge_b850v3_lvds_edid_read,
225 };
226
ge_b850v3_lvds_init(struct device * dev)227 static int ge_b850v3_lvds_init(struct device *dev)
228 {
229 mutex_lock(&ge_b850v3_lvds_dev_mutex);
230
231 if (ge_b850v3_lvds_ptr)
232 goto success;
233
234 ge_b850v3_lvds_ptr = devm_kzalloc(dev,
235 sizeof(*ge_b850v3_lvds_ptr),
236 GFP_KERNEL);
237
238 if (!ge_b850v3_lvds_ptr) {
239 mutex_unlock(&ge_b850v3_lvds_dev_mutex);
240 return -ENOMEM;
241 }
242
243 success:
244 mutex_unlock(&ge_b850v3_lvds_dev_mutex);
245 return 0;
246 }
247
ge_b850v3_lvds_remove(void)248 static void ge_b850v3_lvds_remove(void)
249 {
250 mutex_lock(&ge_b850v3_lvds_dev_mutex);
251 /*
252 * This check is to avoid both the drivers
253 * removing the bridge in their remove() function
254 */
255 if (!ge_b850v3_lvds_ptr ||
256 !ge_b850v3_lvds_ptr->stdp2690_i2c ||
257 !ge_b850v3_lvds_ptr->stdp4028_i2c)
258 goto out;
259
260 drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
261
262 ge_b850v3_lvds_ptr = NULL;
263 out:
264 mutex_unlock(&ge_b850v3_lvds_dev_mutex);
265 }
266
ge_b850v3_register(void)267 static int ge_b850v3_register(void)
268 {
269 struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c;
270 struct device *dev = &stdp4028_i2c->dev;
271
272 /* drm bridge initialization */
273 ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
274 ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT |
275 DRM_BRIDGE_OP_EDID;
276 ge_b850v3_lvds_ptr->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
277 ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
278 drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);
279
280 /* Clear pending interrupts since power up. */
281 i2c_smbus_write_word_data(stdp4028_i2c,
282 STDP4028_DPTX_IRQ_STS_REG,
283 STDP4028_DPTX_IRQ_CLEAR);
284
285 if (!stdp4028_i2c->irq)
286 return 0;
287
288 return devm_request_threaded_irq(&stdp4028_i2c->dev,
289 stdp4028_i2c->irq, NULL,
290 ge_b850v3_lvds_irq_handler,
291 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
292 "ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
293 }
294
stdp4028_ge_b850v3_fw_probe(struct i2c_client * stdp4028_i2c)295 static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c)
296 {
297 struct device *dev = &stdp4028_i2c->dev;
298 int ret;
299
300 ret = ge_b850v3_lvds_init(dev);
301
302 if (ret)
303 return ret;
304
305 ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
306 i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
307
308 /* Only register after both bridges are probed */
309 if (!ge_b850v3_lvds_ptr->stdp2690_i2c)
310 return 0;
311
312 return ge_b850v3_register();
313 }
314
stdp4028_ge_b850v3_fw_remove(struct i2c_client * stdp4028_i2c)315 static void stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
316 {
317 ge_b850v3_lvds_remove();
318 }
319
320 static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
321 {"stdp4028_ge_fw", 0},
322 {},
323 };
324 MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);
325
326 static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
327 { .compatible = "megachips,stdp4028-ge-b850v3-fw" },
328 {},
329 };
330 MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);
331
332 static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
333 .id_table = stdp4028_ge_b850v3_fw_i2c_table,
334 .probe = stdp4028_ge_b850v3_fw_probe,
335 .remove = stdp4028_ge_b850v3_fw_remove,
336 .driver = {
337 .name = "stdp4028-ge-b850v3-fw",
338 .of_match_table = stdp4028_ge_b850v3_fw_match,
339 },
340 };
341
stdp2690_ge_b850v3_fw_probe(struct i2c_client * stdp2690_i2c)342 static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c)
343 {
344 struct device *dev = &stdp2690_i2c->dev;
345 int ret;
346
347 ret = ge_b850v3_lvds_init(dev);
348
349 if (ret)
350 return ret;
351
352 ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
353 i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
354
355 /* Only register after both bridges are probed */
356 if (!ge_b850v3_lvds_ptr->stdp4028_i2c)
357 return 0;
358
359 return ge_b850v3_register();
360 }
361
stdp2690_ge_b850v3_fw_remove(struct i2c_client * stdp2690_i2c)362 static void stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
363 {
364 ge_b850v3_lvds_remove();
365 }
366
367 static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
368 {"stdp2690_ge_fw", 0},
369 {},
370 };
371 MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);
372
373 static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
374 { .compatible = "megachips,stdp2690-ge-b850v3-fw" },
375 {},
376 };
377 MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);
378
379 static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
380 .id_table = stdp2690_ge_b850v3_fw_i2c_table,
381 .probe = stdp2690_ge_b850v3_fw_probe,
382 .remove = stdp2690_ge_b850v3_fw_remove,
383 .driver = {
384 .name = "stdp2690-ge-b850v3-fw",
385 .of_match_table = stdp2690_ge_b850v3_fw_match,
386 },
387 };
388
stdpxxxx_ge_b850v3_init(void)389 static int __init stdpxxxx_ge_b850v3_init(void)
390 {
391 int ret;
392
393 ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
394 if (ret)
395 return ret;
396
397 ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
398 if (ret)
399 i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
400
401 return ret;
402 }
403 module_init(stdpxxxx_ge_b850v3_init);
404
stdpxxxx_ge_b850v3_exit(void)405 static void __exit stdpxxxx_ge_b850v3_exit(void)
406 {
407 i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
408 i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
409 }
410 module_exit(stdpxxxx_ge_b850v3_exit);
411
412 MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
413 MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
414 MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
415 MODULE_LICENSE("GPL v2");
416