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/display/drm_dp_dual_mode_helper.h>
31 #include <drm/drm_device.h>
32 #include <drm/drm_print.h>
33 
34 /**
35  * DOC: dp dual mode helpers
36  *
37  * Helper functions to deal with DP dual mode (aka. DP++) adaptors.
38  *
39  * Type 1:
40  * Adaptor registers (if any) and the sink DDC bus may be accessed via I2C.
41  *
42  * Type 2:
43  * Adaptor registers and sink DDC bus can be accessed either via I2C or
44  * I2C-over-AUX. Source devices may choose to implement either of these
45  * access methods.
46  */
47 
48 #define DP_DUAL_MODE_SLAVE_ADDRESS 0x40
49 
50 /**
51  * drm_dp_dual_mode_read - Read from the DP dual mode adaptor register(s)
52  * @adapter: I2C adapter for the DDC bus
53  * @offset: register offset
54  * @buffer: buffer for return data
55  * @size: sizo of the buffer
56  *
57  * Reads @size bytes from the DP dual mode adaptor registers
58  * starting at @offset.
59  *
60  * Returns:
61  * 0 on success, negative error code on failure
62  */
63 ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
64 			      u8 offset, void *buffer, size_t size)
65 {
66 	u8 zero = 0;
67 	char *tmpbuf = NULL;
68 	/*
69 	 * As sub-addressing is not supported by all adaptors,
70 	 * always explicitly read from the start and discard
71 	 * any bytes that come before the requested offset.
72 	 * This way, no matter whether the adaptor supports it
73 	 * or not, we'll end up reading the proper data.
74 	 */
75 	struct i2c_msg msgs[] = {
76 		{
77 			.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
78 			.flags = 0,
79 			.len = 1,
80 			.buf = &zero,
81 		},
82 		{
83 			.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
84 			.flags = I2C_M_RD,
85 			.len = size + offset,
86 			.buf = buffer,
87 		},
88 	};
89 	int ret;
90 
91 	if (offset) {
92 		tmpbuf = kmalloc(size + offset, GFP_KERNEL);
93 		if (!tmpbuf)
94 			return -ENOMEM;
95 
96 		msgs[1].buf = tmpbuf;
97 	}
98 
99 	ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
100 	if (tmpbuf)
101 		memcpy(buffer, tmpbuf + offset, size);
102 
103 	kfree(tmpbuf);
104 
105 	if (ret < 0)
106 		return ret;
107 	if (ret != ARRAY_SIZE(msgs))
108 		return -EPROTO;
109 
110 	return 0;
111 }
112 EXPORT_SYMBOL(drm_dp_dual_mode_read);
113 
114 /**
115  * drm_dp_dual_mode_write - Write to the DP dual mode adaptor register(s)
116  * @adapter: I2C adapter for the DDC bus
117  * @offset: register offset
118  * @buffer: buffer for write data
119  * @size: sizo of the buffer
120  *
121  * Writes @size bytes to the DP dual mode adaptor registers
122  * starting at @offset.
123  *
124  * Returns:
125  * 0 on success, negative error code on failure
126  */
127 ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
128 			       u8 offset, const void *buffer, size_t size)
129 {
130 	struct i2c_msg msg = {
131 		.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
132 		.flags = 0,
133 		.len = 1 + size,
134 		.buf = NULL,
135 	};
136 	void *data;
137 	int ret;
138 
139 	data = kmalloc(msg.len, GFP_KERNEL);
140 	if (!data)
141 		return -ENOMEM;
142 
143 	msg.buf = data;
144 
145 	memcpy(data, &offset, 1);
146 	memcpy(data + 1, buffer, size);
147 
148 	ret = i2c_transfer(adapter, &msg, 1);
149 
150 	kfree(data);
151 
152 	if (ret < 0)
153 		return ret;
154 	if (ret != 1)
155 		return -EPROTO;
156 
157 	return 0;
158 }
159 EXPORT_SYMBOL(drm_dp_dual_mode_write);
160 
161 static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
162 {
163 	static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
164 		"DP-HDMI ADAPTOR\x04";
165 
166 	return memcmp(hdmi_id, dp_dual_mode_hdmi_id,
167 		      sizeof(dp_dual_mode_hdmi_id)) == 0;
168 }
169 
170 static bool is_type1_adaptor(uint8_t adaptor_id)
171 {
172 	return adaptor_id == 0 || adaptor_id == 0xff;
173 }
174 
175 static bool is_type2_adaptor(uint8_t adaptor_id)
176 {
177 	return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
178 			      DP_DUAL_MODE_REV_TYPE2);
179 }
180 
181 static bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
182 			      const uint8_t adaptor_id)
183 {
184 	return is_hdmi_adaptor(hdmi_id) &&
185 		(adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
186 		 DP_DUAL_MODE_TYPE_HAS_DPCD));
187 }
188 
189 /**
190  * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
191  * @dev: &drm_device to use
192  * @adapter: I2C adapter for the DDC bus
193  *
194  * Attempt to identify the type of the DP dual mode adaptor used.
195  *
196  * Note that when the answer is @DRM_DP_DUAL_MODE_UNKNOWN it's not
197  * certain whether we're dealing with a native HDMI port or
198  * a type 1 DVI dual mode adaptor. The driver will have to use
199  * some other hardware/driver specific mechanism to make that
200  * distinction.
201  *
202  * Returns:
203  * The type of the DP dual mode adaptor used
204  */
205 enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(const struct drm_device *dev,
206 						   struct i2c_adapter *adapter)
207 {
208 	char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] = {};
209 	uint8_t adaptor_id = 0x00;
210 	ssize_t ret;
211 
212 	/*
213 	 * Let's see if the adaptor is there the by reading the
214 	 * HDMI ID registers.
215 	 *
216 	 * Note that type 1 DVI adaptors are not required to implemnt
217 	 * any registers, and that presents a problem for detection.
218 	 * If the i2c transfer is nacked, we may or may not be dealing
219 	 * with a type 1 DVI adaptor. Some other mechanism of detecting
220 	 * the presence of the adaptor is required. One way would be
221 	 * to check the state of the CONFIG1 pin, Another method would
222 	 * simply require the driver to know whether the port is a DP++
223 	 * port or a native HDMI port. Both of these methods are entirely
224 	 * hardware/driver specific so we can't deal with them here.
225 	 */
226 	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_HDMI_ID,
227 				    hdmi_id, sizeof(hdmi_id));
228 	drm_dbg_kms(dev, "DP dual mode HDMI ID: %*pE (err %zd)\n",
229 		    ret ? 0 : (int)sizeof(hdmi_id), hdmi_id, ret);
230 	if (ret)
231 		return DRM_DP_DUAL_MODE_UNKNOWN;
232 
233 	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
234 				    &adaptor_id, sizeof(adaptor_id));
235 	drm_dbg_kms(dev, "DP dual mode adaptor ID: %02x (err %zd)\n", adaptor_id, ret);
236 	if (ret == 0) {
237 		if (is_lspcon_adaptor(hdmi_id, adaptor_id))
238 			return DRM_DP_DUAL_MODE_LSPCON;
239 		if (is_type2_adaptor(adaptor_id)) {
240 			if (is_hdmi_adaptor(hdmi_id))
241 				return DRM_DP_DUAL_MODE_TYPE2_HDMI;
242 			else
243 				return DRM_DP_DUAL_MODE_TYPE2_DVI;
244 		}
245 		/*
246 		 * If not a proper type 1 ID, still assume type 1, but let
247 		 * the user know that we may have misdetected the type.
248 		 */
249 		if (!is_type1_adaptor(adaptor_id))
250 			drm_err(dev, "Unexpected DP dual mode adaptor ID %02x\n", adaptor_id);
251 
252 	}
253 
254 	if (is_hdmi_adaptor(hdmi_id))
255 		return DRM_DP_DUAL_MODE_TYPE1_HDMI;
256 	else
257 		return DRM_DP_DUAL_MODE_TYPE1_DVI;
258 }
259 EXPORT_SYMBOL(drm_dp_dual_mode_detect);
260 
261 /**
262  * drm_dp_dual_mode_max_tmds_clock - Max TMDS clock for DP dual mode adaptor
263  * @dev: &drm_device to use
264  * @type: DP dual mode adaptor type
265  * @adapter: I2C adapter for the DDC bus
266  *
267  * Determine the max TMDS clock the adaptor supports based on the
268  * type of the dual mode adaptor and the DP_DUAL_MODE_MAX_TMDS_CLOCK
269  * register (on type2 adaptors). As some type 1 adaptors have
270  * problems with registers (see comments in drm_dp_dual_mode_detect())
271  * we don't read the register on those, instead we simply assume
272  * a 165 MHz limit based on the specification.
273  *
274  * Returns:
275  * Maximum supported TMDS clock rate for the DP dual mode adaptor in kHz.
276  */
277 int drm_dp_dual_mode_max_tmds_clock(const struct drm_device *dev, enum drm_dp_dual_mode_type type,
278 				    struct i2c_adapter *adapter)
279 {
280 	uint8_t max_tmds_clock;
281 	ssize_t ret;
282 
283 	/* native HDMI so no limit */
284 	if (type == DRM_DP_DUAL_MODE_NONE)
285 		return 0;
286 
287 	/*
288 	 * Type 1 adaptors are limited to 165MHz
289 	 * Type 2 adaptors can tells us their limit
290 	 */
291 	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
292 		return 165000;
293 
294 	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_MAX_TMDS_CLOCK,
295 				    &max_tmds_clock, sizeof(max_tmds_clock));
296 	if (ret || max_tmds_clock == 0x00 || max_tmds_clock == 0xff) {
297 		drm_dbg_kms(dev, "Failed to query max TMDS clock\n");
298 		return 165000;
299 	}
300 
301 	return max_tmds_clock * 5000 / 2;
302 }
303 EXPORT_SYMBOL(drm_dp_dual_mode_max_tmds_clock);
304 
305 /**
306  * drm_dp_dual_mode_get_tmds_output - Get the state of the TMDS output buffers in the DP dual mode adaptor
307  * @dev: &drm_device to use
308  * @type: DP dual mode adaptor type
309  * @adapter: I2C adapter for the DDC bus
310  * @enabled: current state of the TMDS output buffers
311  *
312  * Get the state of the TMDS output buffers in the adaptor. For
313  * type2 adaptors this is queried from the DP_DUAL_MODE_TMDS_OEN
314  * register. As some type 1 adaptors have problems with registers
315  * (see comments in drm_dp_dual_mode_detect()) we don't read the
316  * register on those, instead we simply assume that the buffers
317  * are always enabled.
318  *
319  * Returns:
320  * 0 on success, negative error code on failure
321  */
322 int drm_dp_dual_mode_get_tmds_output(const struct drm_device *dev,
323 				     enum drm_dp_dual_mode_type type, struct i2c_adapter *adapter,
324 				     bool *enabled)
325 {
326 	uint8_t tmds_oen;
327 	ssize_t ret;
328 
329 	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI) {
330 		*enabled = true;
331 		return 0;
332 	}
333 
334 	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
335 				    &tmds_oen, sizeof(tmds_oen));
336 	if (ret) {
337 		drm_dbg_kms(dev, "Failed to query state of TMDS output buffers\n");
338 		return ret;
339 	}
340 
341 	*enabled = !(tmds_oen & DP_DUAL_MODE_TMDS_DISABLE);
342 
343 	return 0;
344 }
345 EXPORT_SYMBOL(drm_dp_dual_mode_get_tmds_output);
346 
347 /**
348  * drm_dp_dual_mode_set_tmds_output - Enable/disable TMDS output buffers in the DP dual mode adaptor
349  * @dev: &drm_device to use
350  * @type: DP dual mode adaptor type
351  * @adapter: I2C adapter for the DDC bus
352  * @enable: enable (as opposed to disable) the TMDS output buffers
353  *
354  * Set the state of the TMDS output buffers in the adaptor. For
355  * type2 this is set via the DP_DUAL_MODE_TMDS_OEN register.
356  * Type1 adaptors do not support any register writes.
357  *
358  * Returns:
359  * 0 on success, negative error code on failure
360  */
361 int drm_dp_dual_mode_set_tmds_output(const struct drm_device *dev, enum drm_dp_dual_mode_type type,
362 				     struct i2c_adapter *adapter, bool enable)
363 {
364 	uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
365 	ssize_t ret;
366 	int retry;
367 
368 	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
369 		return 0;
370 
371 	/*
372 	 * LSPCON adapters in low-power state may ignore the first write, so
373 	 * read back and verify the written value a few times.
374 	 */
375 	for (retry = 0; retry < 3; retry++) {
376 		uint8_t tmp;
377 
378 		ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
379 					     &tmds_oen, sizeof(tmds_oen));
380 		if (ret) {
381 			drm_dbg_kms(dev, "Failed to %s TMDS output buffers (%d attempts)\n",
382 				    enable ? "enable" : "disable", retry + 1);
383 			return ret;
384 		}
385 
386 		ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
387 					    &tmp, sizeof(tmp));
388 		if (ret) {
389 			drm_dbg_kms(dev,
390 				    "I2C read failed during TMDS output buffer %s (%d attempts)\n",
391 				    enable ? "enabling" : "disabling", retry + 1);
392 			return ret;
393 		}
394 
395 		if (tmp == tmds_oen)
396 			return 0;
397 	}
398 
399 	drm_dbg_kms(dev, "I2C write value mismatch during TMDS output buffer %s\n",
400 		    enable ? "enabling" : "disabling");
401 
402 	return -EIO;
403 }
404 EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
405 
406 /**
407  * drm_dp_get_dual_mode_type_name - Get the name of the DP dual mode adaptor type as a string
408  * @type: DP dual mode adaptor type
409  *
410  * Returns:
411  * String representation of the DP dual mode adaptor type
412  */
413 const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
414 {
415 	switch (type) {
416 	case DRM_DP_DUAL_MODE_NONE:
417 		return "none";
418 	case DRM_DP_DUAL_MODE_TYPE1_DVI:
419 		return "type 1 DVI";
420 	case DRM_DP_DUAL_MODE_TYPE1_HDMI:
421 		return "type 1 HDMI";
422 	case DRM_DP_DUAL_MODE_TYPE2_DVI:
423 		return "type 2 DVI";
424 	case DRM_DP_DUAL_MODE_TYPE2_HDMI:
425 		return "type 2 HDMI";
426 	case DRM_DP_DUAL_MODE_LSPCON:
427 		return "lspcon";
428 	default:
429 		WARN_ON(type != DRM_DP_DUAL_MODE_UNKNOWN);
430 		return "unknown";
431 	}
432 }
433 EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
434 
435 /**
436  * drm_lspcon_get_mode: Get LSPCON's current mode of operation by
437  * reading offset (0x80, 0x41)
438  * @dev: &drm_device to use
439  * @adapter: I2C-over-aux adapter
440  * @mode: current lspcon mode of operation output variable
441  *
442  * Returns:
443  * 0 on success, sets the current_mode value to appropriate mode
444  * -error on failure
445  */
446 int drm_lspcon_get_mode(const struct drm_device *dev, struct i2c_adapter *adapter,
447 			enum drm_lspcon_mode *mode)
448 {
449 	u8 data;
450 	int ret = 0;
451 	int retry;
452 
453 	if (!mode) {
454 		drm_err(dev, "NULL input\n");
455 		return -EINVAL;
456 	}
457 
458 	/* Read Status: i2c over aux */
459 	for (retry = 0; retry < 6; retry++) {
460 		if (retry)
461 			usleep_range(500, 1000);
462 
463 		ret = drm_dp_dual_mode_read(adapter,
464 					    DP_DUAL_MODE_LSPCON_CURRENT_MODE,
465 					    &data, sizeof(data));
466 		if (!ret)
467 			break;
468 	}
469 
470 	if (ret < 0) {
471 		drm_dbg_kms(dev, "LSPCON read(0x80, 0x41) failed\n");
472 		return -EFAULT;
473 	}
474 
475 	if (data & DP_DUAL_MODE_LSPCON_MODE_PCON)
476 		*mode = DRM_LSPCON_MODE_PCON;
477 	else
478 		*mode = DRM_LSPCON_MODE_LS;
479 	return 0;
480 }
481 EXPORT_SYMBOL(drm_lspcon_get_mode);
482 
483 /**
484  * drm_lspcon_set_mode: Change LSPCON's mode of operation by
485  * writing offset (0x80, 0x40)
486  * @dev: &drm_device to use
487  * @adapter: I2C-over-aux adapter
488  * @mode: required mode of operation
489  *
490  * Returns:
491  * 0 on success, -error on failure/timeout
492  */
493 int drm_lspcon_set_mode(const struct drm_device *dev, struct i2c_adapter *adapter,
494 			enum drm_lspcon_mode mode)
495 {
496 	u8 data = 0;
497 	int ret;
498 	int time_out = 200;
499 	enum drm_lspcon_mode current_mode;
500 
501 	if (mode == DRM_LSPCON_MODE_PCON)
502 		data = DP_DUAL_MODE_LSPCON_MODE_PCON;
503 
504 	/* Change mode */
505 	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
506 				     &data, sizeof(data));
507 	if (ret < 0) {
508 		drm_err(dev, "LSPCON mode change failed\n");
509 		return ret;
510 	}
511 
512 	/*
513 	 * Confirm mode change by reading the status bit.
514 	 * Sometimes, it takes a while to change the mode,
515 	 * so wait and retry until time out or done.
516 	 */
517 	do {
518 		ret = drm_lspcon_get_mode(dev, adapter, &current_mode);
519 		if (ret) {
520 			drm_err(dev, "can't confirm LSPCON mode change\n");
521 			return ret;
522 		} else {
523 			if (current_mode != mode) {
524 				msleep(10);
525 				time_out -= 10;
526 			} else {
527 				drm_dbg_kms(dev, "LSPCON mode changed to %s\n",
528 					    mode == DRM_LSPCON_MODE_LS ? "LS" : "PCON");
529 				return 0;
530 			}
531 		}
532 	} while (time_out);
533 
534 	drm_err(dev, "LSPCON mode change timed out\n");
535 	return -ETIMEDOUT;
536 }
537 EXPORT_SYMBOL(drm_lspcon_set_mode);
538