Commit | Line | Data |
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a4fc5ed6 KP |
1 | /* |
2 | * Copyright © 2009 Keith Packard | |
3 | * | |
4 | * Permission to use, copy, modify, distribute, and sell this software and its | |
5 | * documentation for any purpose is hereby granted without fee, provided that | |
6 | * the above copyright notice appear in all copies and that both that copyright | |
7 | * notice and this permission notice appear in supporting documentation, and | |
8 | * that the name of the copyright holders not be used in advertising or | |
9 | * publicity pertaining to distribution of the software without specific, | |
10 | * written prior permission. The copyright holders make no representations | |
11 | * about the suitability of this software for any purpose. It is provided "as | |
12 | * is" without express or implied warranty. | |
13 | * | |
14 | * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, | |
15 | * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO | |
16 | * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR | |
17 | * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, | |
18 | * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER | |
19 | * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE | |
20 | * OF THIS SOFTWARE. | |
21 | */ | |
22 | ||
23 | #include <linux/kernel.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/delay.h> | |
a4fc5ed6 KP |
26 | #include <linux/init.h> |
27 | #include <linux/errno.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/i2c.h> | |
760285e7 DH |
30 | #include <drm/drm_dp_helper.h> |
31 | #include <drm/drmP.h> | |
a4fc5ed6 | 32 | |
28164fda DV |
33 | /** |
34 | * DOC: dp helpers | |
35 | * | |
36 | * These functions contain some common logic and helpers at various abstraction | |
37 | * levels to deal with Display Port sink devices and related things like DP aux | |
38 | * channel transfers, EDID reading over DP aux channels, decoding certain DPCD | |
39 | * blocks, ... | |
40 | */ | |
41 | ||
1ffdff13 | 42 | /* Helpers for DP link training */ |
0aec2881 | 43 | static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r) |
1ffdff13 DV |
44 | { |
45 | return link_status[r - DP_LANE0_1_STATUS]; | |
46 | } | |
47 | ||
0aec2881 | 48 | static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
49 | int lane) |
50 | { | |
51 | int i = DP_LANE0_1_STATUS + (lane >> 1); | |
52 | int s = (lane & 1) * 4; | |
53 | u8 l = dp_link_status(link_status, i); | |
54 | return (l >> s) & 0xf; | |
55 | } | |
56 | ||
0aec2881 | 57 | bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
58 | int lane_count) |
59 | { | |
60 | u8 lane_align; | |
61 | u8 lane_status; | |
62 | int lane; | |
63 | ||
64 | lane_align = dp_link_status(link_status, | |
65 | DP_LANE_ALIGN_STATUS_UPDATED); | |
66 | if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0) | |
67 | return false; | |
68 | for (lane = 0; lane < lane_count; lane++) { | |
69 | lane_status = dp_get_lane_status(link_status, lane); | |
70 | if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS) | |
71 | return false; | |
72 | } | |
73 | return true; | |
74 | } | |
75 | EXPORT_SYMBOL(drm_dp_channel_eq_ok); | |
76 | ||
0aec2881 | 77 | bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
78 | int lane_count) |
79 | { | |
80 | int lane; | |
81 | u8 lane_status; | |
82 | ||
83 | for (lane = 0; lane < lane_count; lane++) { | |
84 | lane_status = dp_get_lane_status(link_status, lane); | |
85 | if ((lane_status & DP_LANE_CR_DONE) == 0) | |
86 | return false; | |
87 | } | |
88 | return true; | |
89 | } | |
90 | EXPORT_SYMBOL(drm_dp_clock_recovery_ok); | |
0f037bde | 91 | |
0aec2881 | 92 | u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE], |
0f037bde DV |
93 | int lane) |
94 | { | |
95 | int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); | |
96 | int s = ((lane & 1) ? | |
97 | DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT : | |
98 | DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT); | |
99 | u8 l = dp_link_status(link_status, i); | |
100 | ||
101 | return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT; | |
102 | } | |
103 | EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage); | |
104 | ||
0aec2881 | 105 | u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE], |
0f037bde DV |
106 | int lane) |
107 | { | |
108 | int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); | |
109 | int s = ((lane & 1) ? | |
110 | DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT : | |
111 | DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT); | |
112 | u8 l = dp_link_status(link_status, i); | |
113 | ||
114 | return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT; | |
115 | } | |
116 | EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis); | |
117 | ||
0aec2881 | 118 | void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { |
1a644cd4 DV |
119 | if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) |
120 | udelay(100); | |
121 | else | |
122 | mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); | |
123 | } | |
124 | EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay); | |
125 | ||
0aec2881 | 126 | void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { |
1a644cd4 DV |
127 | if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) |
128 | udelay(400); | |
129 | else | |
130 | mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); | |
131 | } | |
132 | EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay); | |
3b5c662e DV |
133 | |
134 | u8 drm_dp_link_rate_to_bw_code(int link_rate) | |
135 | { | |
136 | switch (link_rate) { | |
137 | case 162000: | |
138 | default: | |
139 | return DP_LINK_BW_1_62; | |
140 | case 270000: | |
141 | return DP_LINK_BW_2_7; | |
142 | case 540000: | |
143 | return DP_LINK_BW_5_4; | |
144 | } | |
145 | } | |
146 | EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code); | |
147 | ||
148 | int drm_dp_bw_code_to_link_rate(u8 link_bw) | |
149 | { | |
150 | switch (link_bw) { | |
151 | case DP_LINK_BW_1_62: | |
152 | default: | |
153 | return 162000; | |
154 | case DP_LINK_BW_2_7: | |
155 | return 270000; | |
156 | case DP_LINK_BW_5_4: | |
157 | return 540000; | |
158 | } | |
159 | } | |
160 | EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate); | |
c197db75 TR |
161 | |
162 | /** | |
163 | * DOC: dp helpers | |
164 | * | |
165 | * The DisplayPort AUX channel is an abstraction to allow generic, driver- | |
166 | * independent access to AUX functionality. Drivers can take advantage of | |
167 | * this by filling in the fields of the drm_dp_aux structure. | |
168 | * | |
169 | * Transactions are described using a hardware-independent drm_dp_aux_msg | |
170 | * structure, which is passed into a driver's .transfer() implementation. | |
171 | * Both native and I2C-over-AUX transactions are supported. | |
c197db75 TR |
172 | */ |
173 | ||
174 | static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, | |
175 | unsigned int offset, void *buffer, size_t size) | |
176 | { | |
177 | struct drm_dp_aux_msg msg; | |
178 | unsigned int retry; | |
179 | int err; | |
180 | ||
181 | memset(&msg, 0, sizeof(msg)); | |
182 | msg.address = offset; | |
183 | msg.request = request; | |
184 | msg.buffer = buffer; | |
185 | msg.size = size; | |
186 | ||
187 | /* | |
188 | * The specification doesn't give any recommendation on how often to | |
19a93f04 DA |
189 | * retry native transactions. We used to retry 7 times like for |
190 | * aux i2c transactions but real world devices this wasn't | |
191 | * sufficient, bump to 32 which makes Dell 4k monitors happier. | |
c197db75 | 192 | */ |
19a93f04 | 193 | for (retry = 0; retry < 32; retry++) { |
4f71d0cb DA |
194 | |
195 | mutex_lock(&aux->hw_mutex); | |
c197db75 | 196 | err = aux->transfer(aux, &msg); |
4f71d0cb | 197 | mutex_unlock(&aux->hw_mutex); |
c197db75 TR |
198 | if (err < 0) { |
199 | if (err == -EBUSY) | |
200 | continue; | |
201 | ||
202 | return err; | |
203 | } | |
204 | ||
c197db75 TR |
205 | |
206 | switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { | |
207 | case DP_AUX_NATIVE_REPLY_ACK: | |
aa17edff DA |
208 | if (err < size) |
209 | return -EPROTO; | |
c197db75 TR |
210 | return err; |
211 | ||
212 | case DP_AUX_NATIVE_REPLY_NACK: | |
213 | return -EIO; | |
214 | ||
215 | case DP_AUX_NATIVE_REPLY_DEFER: | |
216 | usleep_range(400, 500); | |
217 | break; | |
218 | } | |
219 | } | |
220 | ||
743b1e32 | 221 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
c197db75 TR |
222 | return -EIO; |
223 | } | |
224 | ||
225 | /** | |
226 | * drm_dp_dpcd_read() - read a series of bytes from the DPCD | |
227 | * @aux: DisplayPort AUX channel | |
228 | * @offset: address of the (first) register to read | |
229 | * @buffer: buffer to store the register values | |
230 | * @size: number of bytes in @buffer | |
231 | * | |
232 | * Returns the number of bytes transferred on success, or a negative error | |
233 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
234 | * if the retry count was exceeded. If not all bytes were transferred, this | |
235 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
236 | * function, with the exception of -EBUSY (which causes the transaction to | |
237 | * be retried), are propagated to the caller. | |
238 | */ | |
239 | ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, | |
240 | void *buffer, size_t size) | |
241 | { | |
242 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, | |
243 | size); | |
244 | } | |
245 | EXPORT_SYMBOL(drm_dp_dpcd_read); | |
246 | ||
247 | /** | |
248 | * drm_dp_dpcd_write() - write a series of bytes to the DPCD | |
249 | * @aux: DisplayPort AUX channel | |
250 | * @offset: address of the (first) register to write | |
251 | * @buffer: buffer containing the values to write | |
252 | * @size: number of bytes in @buffer | |
253 | * | |
254 | * Returns the number of bytes transferred on success, or a negative error | |
255 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
256 | * if the retry count was exceeded. If not all bytes were transferred, this | |
257 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
258 | * function, with the exception of -EBUSY (which causes the transaction to | |
259 | * be retried), are propagated to the caller. | |
260 | */ | |
261 | ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, | |
262 | void *buffer, size_t size) | |
263 | { | |
264 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, | |
265 | size); | |
266 | } | |
267 | EXPORT_SYMBOL(drm_dp_dpcd_write); | |
8d4adc6a TR |
268 | |
269 | /** | |
270 | * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207) | |
271 | * @aux: DisplayPort AUX channel | |
272 | * @status: buffer to store the link status in (must be at least 6 bytes) | |
273 | * | |
274 | * Returns the number of bytes transferred on success or a negative error | |
275 | * code on failure. | |
276 | */ | |
277 | int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, | |
278 | u8 status[DP_LINK_STATUS_SIZE]) | |
279 | { | |
280 | return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status, | |
281 | DP_LINK_STATUS_SIZE); | |
282 | } | |
283 | EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); | |
516c0f7c TR |
284 | |
285 | /** | |
286 | * drm_dp_link_probe() - probe a DisplayPort link for capabilities | |
287 | * @aux: DisplayPort AUX channel | |
288 | * @link: pointer to structure in which to return link capabilities | |
289 | * | |
290 | * The structure filled in by this function can usually be passed directly | |
291 | * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and | |
292 | * configure the link based on the link's capabilities. | |
293 | * | |
294 | * Returns 0 on success or a negative error code on failure. | |
295 | */ | |
296 | int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
297 | { | |
298 | u8 values[3]; | |
299 | int err; | |
300 | ||
301 | memset(link, 0, sizeof(*link)); | |
302 | ||
303 | err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); | |
304 | if (err < 0) | |
305 | return err; | |
306 | ||
307 | link->revision = values[0]; | |
308 | link->rate = drm_dp_bw_code_to_link_rate(values[1]); | |
309 | link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; | |
310 | ||
311 | if (values[2] & DP_ENHANCED_FRAME_CAP) | |
312 | link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; | |
313 | ||
314 | return 0; | |
315 | } | |
316 | EXPORT_SYMBOL(drm_dp_link_probe); | |
317 | ||
318 | /** | |
319 | * drm_dp_link_power_up() - power up a DisplayPort link | |
320 | * @aux: DisplayPort AUX channel | |
321 | * @link: pointer to a structure containing the link configuration | |
322 | * | |
323 | * Returns 0 on success or a negative error code on failure. | |
324 | */ | |
325 | int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
326 | { | |
327 | u8 value; | |
328 | int err; | |
329 | ||
330 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
331 | if (link->revision < 0x11) | |
332 | return 0; | |
333 | ||
334 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
335 | if (err < 0) | |
336 | return err; | |
337 | ||
338 | value &= ~DP_SET_POWER_MASK; | |
339 | value |= DP_SET_POWER_D0; | |
340 | ||
341 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
342 | if (err < 0) | |
343 | return err; | |
344 | ||
345 | /* | |
346 | * According to the DP 1.1 specification, a "Sink Device must exit the | |
347 | * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink | |
348 | * Control Field" (register 0x600). | |
349 | */ | |
350 | usleep_range(1000, 2000); | |
351 | ||
352 | return 0; | |
353 | } | |
354 | EXPORT_SYMBOL(drm_dp_link_power_up); | |
355 | ||
d816f077 RC |
356 | /** |
357 | * drm_dp_link_power_down() - power down a DisplayPort link | |
358 | * @aux: DisplayPort AUX channel | |
359 | * @link: pointer to a structure containing the link configuration | |
360 | * | |
361 | * Returns 0 on success or a negative error code on failure. | |
362 | */ | |
363 | int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
364 | { | |
365 | u8 value; | |
366 | int err; | |
367 | ||
368 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
369 | if (link->revision < 0x11) | |
370 | return 0; | |
371 | ||
372 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
373 | if (err < 0) | |
374 | return err; | |
375 | ||
376 | value &= ~DP_SET_POWER_MASK; | |
377 | value |= DP_SET_POWER_D3; | |
378 | ||
379 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
380 | if (err < 0) | |
381 | return err; | |
382 | ||
383 | return 0; | |
384 | } | |
385 | EXPORT_SYMBOL(drm_dp_link_power_down); | |
386 | ||
516c0f7c TR |
387 | /** |
388 | * drm_dp_link_configure() - configure a DisplayPort link | |
389 | * @aux: DisplayPort AUX channel | |
390 | * @link: pointer to a structure containing the link configuration | |
391 | * | |
392 | * Returns 0 on success or a negative error code on failure. | |
393 | */ | |
394 | int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
395 | { | |
396 | u8 values[2]; | |
397 | int err; | |
398 | ||
399 | values[0] = drm_dp_link_rate_to_bw_code(link->rate); | |
400 | values[1] = link->num_lanes; | |
401 | ||
402 | if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) | |
403 | values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; | |
404 | ||
405 | err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); | |
406 | if (err < 0) | |
407 | return err; | |
408 | ||
409 | return 0; | |
410 | } | |
411 | EXPORT_SYMBOL(drm_dp_link_configure); | |
88759686 TR |
412 | |
413 | /* | |
414 | * I2C-over-AUX implementation | |
415 | */ | |
416 | ||
417 | static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter) | |
418 | { | |
419 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | | |
420 | I2C_FUNC_SMBUS_READ_BLOCK_DATA | | |
421 | I2C_FUNC_SMBUS_BLOCK_PROC_CALL | | |
422 | I2C_FUNC_10BIT_ADDR; | |
423 | } | |
424 | ||
425 | /* | |
426 | * Transfer a single I2C-over-AUX message and handle various error conditions, | |
732d50b4 AD |
427 | * retrying the transaction as appropriate. It is assumed that the |
428 | * aux->transfer function does not modify anything in the msg other than the | |
429 | * reply field. | |
1d002fa7 SF |
430 | * |
431 | * Returns bytes transferred on success, or a negative error code on failure. | |
88759686 TR |
432 | */ |
433 | static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) | |
434 | { | |
396aa445 | 435 | unsigned int retry, defer_i2c; |
1d002fa7 | 436 | int ret; |
88759686 TR |
437 | |
438 | /* | |
439 | * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device | |
440 | * is required to retry at least seven times upon receiving AUX_DEFER | |
441 | * before giving up the AUX transaction. | |
442 | */ | |
396aa445 | 443 | for (retry = 0, defer_i2c = 0; retry < (7 + defer_i2c); retry++) { |
4f71d0cb | 444 | mutex_lock(&aux->hw_mutex); |
1d002fa7 | 445 | ret = aux->transfer(aux, msg); |
4f71d0cb | 446 | mutex_unlock(&aux->hw_mutex); |
1d002fa7 SF |
447 | if (ret < 0) { |
448 | if (ret == -EBUSY) | |
88759686 TR |
449 | continue; |
450 | ||
1d002fa7 SF |
451 | DRM_DEBUG_KMS("transaction failed: %d\n", ret); |
452 | return ret; | |
88759686 TR |
453 | } |
454 | ||
88759686 TR |
455 | |
456 | switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) { | |
457 | case DP_AUX_NATIVE_REPLY_ACK: | |
458 | /* | |
459 | * For I2C-over-AUX transactions this isn't enough, we | |
460 | * need to check for the I2C ACK reply. | |
461 | */ | |
462 | break; | |
463 | ||
464 | case DP_AUX_NATIVE_REPLY_NACK: | |
fb8c5e49 | 465 | DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size); |
88759686 TR |
466 | return -EREMOTEIO; |
467 | ||
468 | case DP_AUX_NATIVE_REPLY_DEFER: | |
747552b9 | 469 | DRM_DEBUG_KMS("native defer\n"); |
88759686 TR |
470 | /* |
471 | * We could check for I2C bit rate capabilities and if | |
472 | * available adjust this interval. We could also be | |
473 | * more careful with DP-to-legacy adapters where a | |
474 | * long legacy cable may force very low I2C bit rates. | |
475 | * | |
476 | * For now just defer for long enough to hopefully be | |
477 | * safe for all use-cases. | |
478 | */ | |
479 | usleep_range(500, 600); | |
480 | continue; | |
481 | ||
482 | default: | |
483 | DRM_ERROR("invalid native reply %#04x\n", msg->reply); | |
484 | return -EREMOTEIO; | |
485 | } | |
486 | ||
487 | switch (msg->reply & DP_AUX_I2C_REPLY_MASK) { | |
488 | case DP_AUX_I2C_REPLY_ACK: | |
489 | /* | |
490 | * Both native ACK and I2C ACK replies received. We | |
491 | * can assume the transfer was successful. | |
492 | */ | |
1d002fa7 | 493 | return ret; |
88759686 TR |
494 | |
495 | case DP_AUX_I2C_REPLY_NACK: | |
fb8c5e49 | 496 | DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size); |
e9cf6194 | 497 | aux->i2c_nack_count++; |
88759686 TR |
498 | return -EREMOTEIO; |
499 | ||
500 | case DP_AUX_I2C_REPLY_DEFER: | |
501 | DRM_DEBUG_KMS("I2C defer\n"); | |
396aa445 TP |
502 | /* DP Compliance Test 4.2.2.5 Requirement: |
503 | * Must have at least 7 retries for I2C defers on the | |
504 | * transaction to pass this test | |
505 | */ | |
e9cf6194 | 506 | aux->i2c_defer_count++; |
396aa445 TP |
507 | if (defer_i2c < 7) |
508 | defer_i2c++; | |
88759686 TR |
509 | usleep_range(400, 500); |
510 | continue; | |
511 | ||
512 | default: | |
513 | DRM_ERROR("invalid I2C reply %#04x\n", msg->reply); | |
514 | return -EREMOTEIO; | |
515 | } | |
516 | } | |
517 | ||
743b1e32 | 518 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
88759686 TR |
519 | return -EREMOTEIO; |
520 | } | |
521 | ||
1d002fa7 SF |
522 | /* |
523 | * Keep retrying drm_dp_i2c_do_msg until all data has been transferred. | |
524 | * | |
525 | * Returns an error code on failure, or a recommended transfer size on success. | |
526 | */ | |
527 | static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg) | |
528 | { | |
529 | int err, ret = orig_msg->size; | |
530 | struct drm_dp_aux_msg msg = *orig_msg; | |
531 | ||
532 | while (msg.size > 0) { | |
533 | err = drm_dp_i2c_do_msg(aux, &msg); | |
534 | if (err <= 0) | |
535 | return err == 0 ? -EPROTO : err; | |
536 | ||
537 | if (err < msg.size && err < ret) { | |
538 | DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n", | |
539 | msg.size, err); | |
540 | ret = err; | |
541 | } | |
542 | ||
543 | msg.size -= err; | |
544 | msg.buffer += err; | |
545 | } | |
546 | ||
547 | return ret; | |
548 | } | |
549 | ||
550 | /* | |
551 | * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX | |
552 | * packets to be as large as possible. If not, the I2C transactions never | |
553 | * succeed. Hence the default is maximum. | |
554 | */ | |
555 | static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES; | |
556 | module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644); | |
557 | MODULE_PARM_DESC(dp_aux_i2c_transfer_size, | |
558 | "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)"); | |
559 | ||
88759686 TR |
560 | static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, |
561 | int num) | |
562 | { | |
563 | struct drm_dp_aux *aux = adapter->algo_data; | |
564 | unsigned int i, j; | |
1d002fa7 | 565 | unsigned transfer_size; |
ccdb516e AD |
566 | struct drm_dp_aux_msg msg; |
567 | int err = 0; | |
88759686 | 568 | |
1d002fa7 SF |
569 | dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES); |
570 | ||
ccdb516e | 571 | memset(&msg, 0, sizeof(msg)); |
88759686 | 572 | |
ccdb516e AD |
573 | for (i = 0; i < num; i++) { |
574 | msg.address = msgs[i].addr; | |
575 | msg.request = (msgs[i].flags & I2C_M_RD) ? | |
576 | DP_AUX_I2C_READ : | |
577 | DP_AUX_I2C_WRITE; | |
578 | msg.request |= DP_AUX_I2C_MOT; | |
579 | /* Send a bare address packet to start the transaction. | |
580 | * Zero sized messages specify an address only (bare | |
581 | * address) transaction. | |
582 | */ | |
583 | msg.buffer = NULL; | |
584 | msg.size = 0; | |
585 | err = drm_dp_i2c_do_msg(aux, &msg); | |
586 | if (err < 0) | |
587 | break; | |
1d002fa7 SF |
588 | /* We want each transaction to be as large as possible, but |
589 | * we'll go to smaller sizes if the hardware gives us a | |
590 | * short reply. | |
88759686 | 591 | */ |
1d002fa7 SF |
592 | transfer_size = dp_aux_i2c_transfer_size; |
593 | for (j = 0; j < msgs[i].len; j += msg.size) { | |
88759686 | 594 | msg.buffer = msgs[i].buf + j; |
1d002fa7 | 595 | msg.size = min(transfer_size, msgs[i].len - j); |
88759686 | 596 | |
1d002fa7 | 597 | err = drm_dp_i2c_drain_msg(aux, &msg); |
88759686 | 598 | if (err < 0) |
ccdb516e | 599 | break; |
1d002fa7 | 600 | transfer_size = err; |
88759686 | 601 | } |
ccdb516e AD |
602 | if (err < 0) |
603 | break; | |
88759686 | 604 | } |
ccdb516e AD |
605 | if (err >= 0) |
606 | err = num; | |
607 | /* Send a bare address packet to close out the transaction. | |
608 | * Zero sized messages specify an address only (bare | |
609 | * address) transaction. | |
610 | */ | |
611 | msg.request &= ~DP_AUX_I2C_MOT; | |
612 | msg.buffer = NULL; | |
613 | msg.size = 0; | |
614 | (void)drm_dp_i2c_do_msg(aux, &msg); | |
88759686 | 615 | |
ccdb516e | 616 | return err; |
88759686 TR |
617 | } |
618 | ||
619 | static const struct i2c_algorithm drm_dp_i2c_algo = { | |
620 | .functionality = drm_dp_i2c_functionality, | |
621 | .master_xfer = drm_dp_i2c_xfer, | |
622 | }; | |
623 | ||
624 | /** | |
4f71d0cb | 625 | * drm_dp_aux_register() - initialise and register aux channel |
88759686 TR |
626 | * @aux: DisplayPort AUX channel |
627 | * | |
628 | * Returns 0 on success or a negative error code on failure. | |
629 | */ | |
4f71d0cb | 630 | int drm_dp_aux_register(struct drm_dp_aux *aux) |
88759686 | 631 | { |
4f71d0cb DA |
632 | mutex_init(&aux->hw_mutex); |
633 | ||
88759686 TR |
634 | aux->ddc.algo = &drm_dp_i2c_algo; |
635 | aux->ddc.algo_data = aux; | |
636 | aux->ddc.retries = 3; | |
637 | ||
638 | aux->ddc.class = I2C_CLASS_DDC; | |
639 | aux->ddc.owner = THIS_MODULE; | |
640 | aux->ddc.dev.parent = aux->dev; | |
641 | aux->ddc.dev.of_node = aux->dev->of_node; | |
642 | ||
9dc40560 JN |
643 | strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev), |
644 | sizeof(aux->ddc.name)); | |
88759686 TR |
645 | |
646 | return i2c_add_adapter(&aux->ddc); | |
647 | } | |
4f71d0cb | 648 | EXPORT_SYMBOL(drm_dp_aux_register); |
88759686 TR |
649 | |
650 | /** | |
4f71d0cb | 651 | * drm_dp_aux_unregister() - unregister an AUX adapter |
88759686 TR |
652 | * @aux: DisplayPort AUX channel |
653 | */ | |
4f71d0cb | 654 | void drm_dp_aux_unregister(struct drm_dp_aux *aux) |
88759686 TR |
655 | { |
656 | i2c_del_adapter(&aux->ddc); | |
657 | } | |
4f71d0cb | 658 | EXPORT_SYMBOL(drm_dp_aux_unregister); |