1 /*
2 * Copyright © 2016 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
21 */
22
23 #include <linux/delay.h>
24 #include <linux/errno.h>
25 #include <linux/export.h>
26 #include <linux/i2c.h>
27 #include <linux/slab.h>
28 #include <linux/string.h>
29
30 #include <drm/drm_dp_dual_mode_helper.h>
31 #include <drm/drm_print.h>
32
33 /**
34 * DOC: dp dual mode helpers
35 *
36 * Helper functions to deal with DP dual mode (aka. DP++) adaptors.
37 *
38 * Type 1:
39 * Adaptor registers (if any) and the sink DDC bus may be accessed via I2C.
40 *
41 * Type 2:
42 * Adaptor registers and sink DDC bus can be accessed either via I2C or
43 * I2C-over-AUX. Source devices may choose to implement either of these
44 * access methods.
45 */
46
47 #define DP_DUAL_MODE_SLAVE_ADDRESS 0x40
48
49 /**
50 * drm_dp_dual_mode_read - Read from the DP dual mode adaptor register(s)
51 * @adapter: I2C adapter for the DDC bus
52 * @offset: register offset
53 * @buffer: buffer for return data
54 * @size: sizo of the buffer
55 *
56 * Reads @size bytes from the DP dual mode adaptor registers
57 * starting at @offset.
58 *
59 * Returns:
60 * 0 on success, negative error code on failure
61 */
62 ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
63 u8 offset, void *buffer, size_t size)
64 {
65 struct i2c_msg msgs[] = {
66 {
67 .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
68 .flags = 0,
69 .len = 1,
70 .buf = &offset,
71 },
72 {
73 .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
74 .flags = I2C_M_RD,
75 .len = size,
76 .buf = buffer,
77 },
78 };
79 int ret;
80
81 ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
82 if (ret < 0)
83 return ret;
84 if (ret != ARRAY_SIZE(msgs))
85 return -EPROTO;
86
87 return 0;
88 }
89 EXPORT_SYMBOL(drm_dp_dual_mode_read);
90
91 /**
92 * drm_dp_dual_mode_write - Write to the DP dual mode adaptor register(s)
93 * @adapter: I2C adapter for the DDC bus
94 * @offset: register offset
95 * @buffer: buffer for write data
96 * @size: sizo of the buffer
97 *
98 * Writes @size bytes to the DP dual mode adaptor registers
99 * starting at @offset.
100 *
101 * Returns:
102 * 0 on success, negative error code on failure
103 */
104 ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
105 u8 offset, const void *buffer, size_t size)
106 {
107 struct i2c_msg msg = {
108 .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
109 .flags = 0,
110 .len = 1 + size,
111 .buf = NULL,
112 };
113 void *data;
114 int ret;
115
116 data = kmalloc(msg.len, GFP_KERNEL);
117 if (!data)
118 return -ENOMEM;
119
120 msg.buf = data;
121
122 memcpy(data, &offset, 1);
123 memcpy(data + 1, buffer, size);
124
125 ret = i2c_transfer(adapter, &msg, 1);
126
127 kfree(data);
128
129 if (ret < 0)
130 return ret;
131 if (ret != 1)
132 return -EPROTO;
133
134 return 0;
135 }
136 EXPORT_SYMBOL(drm_dp_dual_mode_write);
137
138 static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
139 {
140 static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
141 "DP-HDMI ADAPTOR\x04";
142
143 return memcmp(hdmi_id, dp_dual_mode_hdmi_id,
144 sizeof(dp_dual_mode_hdmi_id)) == 0;
145 }
146
147 static bool is_type1_adaptor(uint8_t adaptor_id)
148 {
149 return adaptor_id == 0 || adaptor_id == 0xff;
150 }
151
152 static bool is_type2_adaptor(uint8_t adaptor_id)
153 {
154 return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
155 DP_DUAL_MODE_REV_TYPE2);
156 }
157
158 static bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
159 const uint8_t adaptor_id)
160 {
161 return is_hdmi_adaptor(hdmi_id) &&
162 (adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
163 DP_DUAL_MODE_TYPE_HAS_DPCD));
164 }
165
166 /**
167 * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
168 * @adapter: I2C adapter for the DDC bus
169 *
170 * Attempt to identify the type of the DP dual mode adaptor used.
171 *
172 * Note that when the answer is @DRM_DP_DUAL_MODE_UNKNOWN it's not
173 * certain whether we're dealing with a native HDMI port or
174 * a type 1 DVI dual mode adaptor. The driver will have to use
175 * some other hardware/driver specific mechanism to make that
176 * distinction.
177 *
178 * Returns:
179 * The type of the DP dual mode adaptor used
180 */
181 enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
182 {
183 char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] = {};
184 uint8_t adaptor_id = 0x00;
185 ssize_t ret;
186
187 /*
188 * Let's see if the adaptor is there the by reading the
189 * HDMI ID registers.
190 *
191 * Note that type 1 DVI adaptors are not required to implemnt
192 * any registers, and that presents a problem for detection.
193 * If the i2c transfer is nacked, we may or may not be dealing
194 * with a type 1 DVI adaptor. Some other mechanism of detecting
195 * the presence of the adaptor is required. One way would be
196 * to check the state of the CONFIG1 pin, Another method would
197 * simply require the driver to know whether the port is a DP++
198 * port or a native HDMI port. Both of these methods are entirely
199 * hardware/driver specific so we can't deal with them here.
200 */
201 ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_HDMI_ID,
202 hdmi_id, sizeof(hdmi_id));
203 DRM_DEBUG_KMS("DP dual mode HDMI ID: %*pE (err %zd)\n",
204 ret ? 0 : (int)sizeof(hdmi_id), hdmi_id, ret);
205 if (ret)
206 return DRM_DP_DUAL_MODE_UNKNOWN;
207
208 /*
209 * Sigh. Some (maybe all?) type 1 adaptors are broken and ack
210 * the offset but ignore it, and instead they just always return
211 * data from the start of the HDMI ID buffer. So for a broken
212 * type 1 HDMI adaptor a single byte read will always give us
213 * 0x44, and for a type 1 DVI adaptor it should give 0x00
214 * (assuming it implements any registers). Fortunately neither
215 * of those values will match the type 2 signature of the
216 * DP_DUAL_MODE_ADAPTOR_ID register so we can proceed with
217 * the type 2 adaptor detection safely even in the presence
218 * of broken type 1 adaptors.
219 */
220 ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
221 &adaptor_id, sizeof(adaptor_id));
222 DRM_DEBUG_KMS("DP dual mode adaptor ID: %02x (err %zd)\n",
223 adaptor_id, ret);
224 if (ret == 0) {
225 if (is_lspcon_adaptor(hdmi_id, adaptor_id))
226 return DRM_DP_DUAL_MODE_LSPCON;
227 if (is_type2_adaptor(adaptor_id)) {
228 if (is_hdmi_adaptor(hdmi_id))
229 return DRM_DP_DUAL_MODE_TYPE2_HDMI;
230 else
231 return DRM_DP_DUAL_MODE_TYPE2_DVI;
232 }
233 /*
234 * If neither a proper type 1 ID nor a broken type 1 adaptor
235 * as described above, assume type 1, but let the user know
236 * that we may have misdetected the type.
237 */
238 if (!is_type1_adaptor(adaptor_id) && adaptor_id != hdmi_id[0])
239 DRM_ERROR("Unexpected DP dual mode adaptor ID %02x\n",
240 adaptor_id);
241
242 }
243
244 if (is_hdmi_adaptor(hdmi_id))
245 return DRM_DP_DUAL_MODE_TYPE1_HDMI;
246 else
247 return DRM_DP_DUAL_MODE_TYPE1_DVI;
248 }
249 EXPORT_SYMBOL(drm_dp_dual_mode_detect);
250
251 /**
252 * drm_dp_dual_mode_max_tmds_clock - Max TMDS clock for DP dual mode adaptor
253 * @type: DP dual mode adaptor type
254 * @adapter: I2C adapter for the DDC bus
255 *
256 * Determine the max TMDS clock the adaptor supports based on the
257 * type of the dual mode adaptor and the DP_DUAL_MODE_MAX_TMDS_CLOCK
258 * register (on type2 adaptors). As some type 1 adaptors have
259 * problems with registers (see comments in drm_dp_dual_mode_detect())
260 * we don't read the register on those, instead we simply assume
261 * a 165 MHz limit based on the specification.
262 *
263 * Returns:
264 * Maximum supported TMDS clock rate for the DP dual mode adaptor in kHz.
265 */
266 int drm_dp_dual_mode_max_tmds_clock(enum drm_dp_dual_mode_type type,
267 struct i2c_adapter *adapter)
268 {
269 uint8_t max_tmds_clock;
270 ssize_t ret;
271
272 /* native HDMI so no limit */
273 if (type == DRM_DP_DUAL_MODE_NONE)
274 return 0;
275
276 /*
277 * Type 1 adaptors are limited to 165MHz
278 * Type 2 adaptors can tells us their limit
279 */
280 if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
281 return 165000;
282
283 ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_MAX_TMDS_CLOCK,
284 &max_tmds_clock, sizeof(max_tmds_clock));
285 if (ret || max_tmds_clock == 0x00 || max_tmds_clock == 0xff) {
286 DRM_DEBUG_KMS("Failed to query max TMDS clock\n");
287 return 165000;
288 }
289
290 return max_tmds_clock * 5000 / 2;
291 }
292 EXPORT_SYMBOL(drm_dp_dual_mode_max_tmds_clock);
293
294 /**
295 * drm_dp_dual_mode_get_tmds_output - Get the state of the TMDS output buffers in the DP dual mode adaptor
296 * @type: DP dual mode adaptor type
297 * @adapter: I2C adapter for the DDC bus
298 * @enabled: current state of the TMDS output buffers
299 *
300 * Get the state of the TMDS output buffers in the adaptor. For
301 * type2 adaptors this is queried from the DP_DUAL_MODE_TMDS_OEN
302 * register. As some type 1 adaptors have problems with registers
303 * (see comments in drm_dp_dual_mode_detect()) we don't read the
304 * register on those, instead we simply assume that the buffers
305 * are always enabled.
306 *
307 * Returns:
308 * 0 on success, negative error code on failure
309 */
310 int drm_dp_dual_mode_get_tmds_output(enum drm_dp_dual_mode_type type,
311 struct i2c_adapter *adapter,
312 bool *enabled)
313 {
314 uint8_t tmds_oen;
315 ssize_t ret;
316
317 if (type < DRM_DP_DUAL_MODE_TYPE2_DVI) {
318 *enabled = true;
319 return 0;
320 }
321
322 ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
323 &tmds_oen, sizeof(tmds_oen));
324 if (ret) {
325 DRM_DEBUG_KMS("Failed to query state of TMDS output buffers\n");
326 return ret;
327 }
328
329 *enabled = !(tmds_oen & DP_DUAL_MODE_TMDS_DISABLE);
330
331 return 0;
332 }
333 EXPORT_SYMBOL(drm_dp_dual_mode_get_tmds_output);
334
335 /**
336 * drm_dp_dual_mode_set_tmds_output - Enable/disable TMDS output buffers in the DP dual mode adaptor
337 * @type: DP dual mode adaptor type
338 * @adapter: I2C adapter for the DDC bus
339 * @enable: enable (as opposed to disable) the TMDS output buffers
340 *
341 * Set the state of the TMDS output buffers in the adaptor. For
342 * type2 this is set via the DP_DUAL_MODE_TMDS_OEN register. As
343 * some type 1 adaptors have problems with registers (see comments
344 * in drm_dp_dual_mode_detect()) we avoid touching the register,
345 * making this function a no-op on type 1 adaptors.
346 *
347 * Returns:
348 * 0 on success, negative error code on failure
349 */
350 int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
351 struct i2c_adapter *adapter, bool enable)
352 {
353 uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
354 ssize_t ret;
355 int retry;
356
357 if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
358 return 0;
359
360 /*
361 * LSPCON adapters in low-power state may ignore the first write, so
362 * read back and verify the written value a few times.
363 */
364 for (retry = 0; retry < 3; retry++) {
365 uint8_t tmp;
366
367 ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
368 &tmds_oen, sizeof(tmds_oen));
369 if (ret) {
370 DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n",
371 enable ? "enable" : "disable",
372 retry + 1);
373 return ret;
374 }
375
376 ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
377 &tmp, sizeof(tmp));
378 if (ret) {
379 DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n",
380 enable ? "enabling" : "disabling",
381 retry + 1);
382 return ret;
383 }
384
385 if (tmp == tmds_oen)
386 return 0;
387 }
388
389 DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n",
390 enable ? "enabling" : "disabling");
391
392 return -EIO;
393 }
394 EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
395
396 /**
397 * drm_dp_get_dual_mode_type_name - Get the name of the DP dual mode adaptor type as a string
398 * @type: DP dual mode adaptor type
399 *
400 * Returns:
401 * String representation of the DP dual mode adaptor type
402 */
403 const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
404 {
405 switch (type) {
406 case DRM_DP_DUAL_MODE_NONE:
407 return "none";
408 case DRM_DP_DUAL_MODE_TYPE1_DVI:
409 return "type 1 DVI";
410 case DRM_DP_DUAL_MODE_TYPE1_HDMI:
411 return "type 1 HDMI";
412 case DRM_DP_DUAL_MODE_TYPE2_DVI:
413 return "type 2 DVI";
414 case DRM_DP_DUAL_MODE_TYPE2_HDMI:
415 return "type 2 HDMI";
416 case DRM_DP_DUAL_MODE_LSPCON:
417 return "lspcon";
418 default:
419 WARN_ON(type != DRM_DP_DUAL_MODE_UNKNOWN);
420 return "unknown";
421 }
422 }
423 EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
424
425 /**
426 * drm_lspcon_get_mode: Get LSPCON's current mode of operation by
427 * reading offset (0x80, 0x41)
428 * @adapter: I2C-over-aux adapter
429 * @mode: current lspcon mode of operation output variable
430 *
431 * Returns:
432 * 0 on success, sets the current_mode value to appropriate mode
433 * -error on failure
434 */
435 int drm_lspcon_get_mode(struct i2c_adapter *adapter,
436 enum drm_lspcon_mode *mode)
437 {
438 u8 data;
439 int ret = 0;
440 int retry;
441
442 if (!mode) {
443 DRM_ERROR("NULL input\n");
444 return -EINVAL;
445 }
446
447 /* Read Status: i2c over aux */
448 for (retry = 0; retry < 6; retry++) {
449 if (retry)
450 usleep_range(500, 1000);
451
452 ret = drm_dp_dual_mode_read(adapter,
453 DP_DUAL_MODE_LSPCON_CURRENT_MODE,
454 &data, sizeof(data));
455 if (!ret)
456 break;
457 }
458
459 if (ret < 0) {
460 DRM_DEBUG_KMS("LSPCON read(0x80, 0x41) failed\n");
461 return -EFAULT;
462 }
463
464 if (data & DP_DUAL_MODE_LSPCON_MODE_PCON)
465 *mode = DRM_LSPCON_MODE_PCON;
466 else
467 *mode = DRM_LSPCON_MODE_LS;
468 return 0;
469 }
470 EXPORT_SYMBOL(drm_lspcon_get_mode);
471
472 /**
473 * drm_lspcon_set_mode: Change LSPCON's mode of operation by
474 * writing offset (0x80, 0x40)
475 * @adapter: I2C-over-aux adapter
476 * @mode: required mode of operation
477 *
478 * Returns:
479 * 0 on success, -error on failure/timeout
480 */
481 int drm_lspcon_set_mode(struct i2c_adapter *adapter,
482 enum drm_lspcon_mode mode)
483 {
484 u8 data = 0;
485 int ret;
486 int time_out = 200;
487 enum drm_lspcon_mode current_mode;
488
489 if (mode == DRM_LSPCON_MODE_PCON)
490 data = DP_DUAL_MODE_LSPCON_MODE_PCON;
491
492 /* Change mode */
493 ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
494 &data, sizeof(data));
495 if (ret < 0) {
496 DRM_ERROR("LSPCON mode change failed\n");
497 return ret;
498 }
499
500 /*
501 * Confirm mode change by reading the status bit.
502 * Sometimes, it takes a while to change the mode,
503 * so wait and retry until time out or done.
504 */
505 do {
506 ret = drm_lspcon_get_mode(adapter, ¤t_mode);
507 if (ret) {
508 DRM_ERROR("can't confirm LSPCON mode change\n");
509 return ret;
510 } else {
511 if (current_mode != mode) {
512 msleep(10);
513 time_out -= 10;
514 } else {
515 DRM_DEBUG_KMS("LSPCON mode changed to %s\n",
516 mode == DRM_LSPCON_MODE_LS ?
517 "LS" : "PCON");
518 return 0;
519 }
520 }
521 } while (time_out);
522
523 DRM_ERROR("LSPCON mode change timed out\n");
524 return -ETIMEDOUT;
525 }
526 EXPORT_SYMBOL(drm_lspcon_set_mode);