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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 | 161 | |
79a2b161 VS |
162 | #define AUX_RETRY_INTERVAL 500 /* us */ |
163 | ||
c197db75 TR |
164 | /** |
165 | * DOC: dp helpers | |
166 | * | |
167 | * The DisplayPort AUX channel is an abstraction to allow generic, driver- | |
168 | * independent access to AUX functionality. Drivers can take advantage of | |
169 | * this by filling in the fields of the drm_dp_aux structure. | |
170 | * | |
171 | * Transactions are described using a hardware-independent drm_dp_aux_msg | |
172 | * structure, which is passed into a driver's .transfer() implementation. | |
173 | * Both native and I2C-over-AUX transactions are supported. | |
c197db75 TR |
174 | */ |
175 | ||
176 | static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, | |
177 | unsigned int offset, void *buffer, size_t size) | |
178 | { | |
179 | struct drm_dp_aux_msg msg; | |
180 | unsigned int retry; | |
181 | int err; | |
182 | ||
183 | memset(&msg, 0, sizeof(msg)); | |
184 | msg.address = offset; | |
185 | msg.request = request; | |
186 | msg.buffer = buffer; | |
187 | msg.size = size; | |
188 | ||
189 | /* | |
190 | * The specification doesn't give any recommendation on how often to | |
19a93f04 DA |
191 | * retry native transactions. We used to retry 7 times like for |
192 | * aux i2c transactions but real world devices this wasn't | |
193 | * sufficient, bump to 32 which makes Dell 4k monitors happier. | |
c197db75 | 194 | */ |
19a93f04 | 195 | for (retry = 0; retry < 32; retry++) { |
4f71d0cb DA |
196 | |
197 | mutex_lock(&aux->hw_mutex); | |
c197db75 | 198 | err = aux->transfer(aux, &msg); |
4f71d0cb | 199 | mutex_unlock(&aux->hw_mutex); |
c197db75 TR |
200 | if (err < 0) { |
201 | if (err == -EBUSY) | |
202 | continue; | |
203 | ||
204 | return err; | |
205 | } | |
206 | ||
c197db75 TR |
207 | |
208 | switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { | |
209 | case DP_AUX_NATIVE_REPLY_ACK: | |
aa17edff DA |
210 | if (err < size) |
211 | return -EPROTO; | |
c197db75 TR |
212 | return err; |
213 | ||
214 | case DP_AUX_NATIVE_REPLY_NACK: | |
215 | return -EIO; | |
216 | ||
217 | case DP_AUX_NATIVE_REPLY_DEFER: | |
79a2b161 | 218 | usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); |
c197db75 TR |
219 | break; |
220 | } | |
221 | } | |
222 | ||
743b1e32 | 223 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
c197db75 TR |
224 | return -EIO; |
225 | } | |
226 | ||
227 | /** | |
228 | * drm_dp_dpcd_read() - read a series of bytes from the DPCD | |
229 | * @aux: DisplayPort AUX channel | |
230 | * @offset: address of the (first) register to read | |
231 | * @buffer: buffer to store the register values | |
232 | * @size: number of bytes in @buffer | |
233 | * | |
234 | * Returns the number of bytes transferred on success, or a negative error | |
235 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
236 | * if the retry count was exceeded. If not all bytes were transferred, this | |
237 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
238 | * function, with the exception of -EBUSY (which causes the transaction to | |
239 | * be retried), are propagated to the caller. | |
240 | */ | |
241 | ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, | |
242 | void *buffer, size_t size) | |
243 | { | |
244 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, | |
245 | size); | |
246 | } | |
247 | EXPORT_SYMBOL(drm_dp_dpcd_read); | |
248 | ||
249 | /** | |
250 | * drm_dp_dpcd_write() - write a series of bytes to the DPCD | |
251 | * @aux: DisplayPort AUX channel | |
252 | * @offset: address of the (first) register to write | |
253 | * @buffer: buffer containing the values to write | |
254 | * @size: number of bytes in @buffer | |
255 | * | |
256 | * Returns the number of bytes transferred on success, or a negative error | |
257 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
258 | * if the retry count was exceeded. If not all bytes were transferred, this | |
259 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
260 | * function, with the exception of -EBUSY (which causes the transaction to | |
261 | * be retried), are propagated to the caller. | |
262 | */ | |
263 | ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, | |
264 | void *buffer, size_t size) | |
265 | { | |
266 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, | |
267 | size); | |
268 | } | |
269 | EXPORT_SYMBOL(drm_dp_dpcd_write); | |
8d4adc6a TR |
270 | |
271 | /** | |
272 | * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207) | |
273 | * @aux: DisplayPort AUX channel | |
274 | * @status: buffer to store the link status in (must be at least 6 bytes) | |
275 | * | |
276 | * Returns the number of bytes transferred on success or a negative error | |
277 | * code on failure. | |
278 | */ | |
279 | int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, | |
280 | u8 status[DP_LINK_STATUS_SIZE]) | |
281 | { | |
282 | return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status, | |
283 | DP_LINK_STATUS_SIZE); | |
284 | } | |
285 | EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); | |
516c0f7c TR |
286 | |
287 | /** | |
288 | * drm_dp_link_probe() - probe a DisplayPort link for capabilities | |
289 | * @aux: DisplayPort AUX channel | |
290 | * @link: pointer to structure in which to return link capabilities | |
291 | * | |
292 | * The structure filled in by this function can usually be passed directly | |
293 | * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and | |
294 | * configure the link based on the link's capabilities. | |
295 | * | |
296 | * Returns 0 on success or a negative error code on failure. | |
297 | */ | |
298 | int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
299 | { | |
300 | u8 values[3]; | |
301 | int err; | |
302 | ||
303 | memset(link, 0, sizeof(*link)); | |
304 | ||
305 | err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); | |
306 | if (err < 0) | |
307 | return err; | |
308 | ||
309 | link->revision = values[0]; | |
310 | link->rate = drm_dp_bw_code_to_link_rate(values[1]); | |
311 | link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; | |
312 | ||
313 | if (values[2] & DP_ENHANCED_FRAME_CAP) | |
314 | link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; | |
315 | ||
316 | return 0; | |
317 | } | |
318 | EXPORT_SYMBOL(drm_dp_link_probe); | |
319 | ||
320 | /** | |
321 | * drm_dp_link_power_up() - power up a DisplayPort link | |
322 | * @aux: DisplayPort AUX channel | |
323 | * @link: pointer to a structure containing the link configuration | |
324 | * | |
325 | * Returns 0 on success or a negative error code on failure. | |
326 | */ | |
327 | int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
328 | { | |
329 | u8 value; | |
330 | int err; | |
331 | ||
332 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
333 | if (link->revision < 0x11) | |
334 | return 0; | |
335 | ||
336 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
337 | if (err < 0) | |
338 | return err; | |
339 | ||
340 | value &= ~DP_SET_POWER_MASK; | |
341 | value |= DP_SET_POWER_D0; | |
342 | ||
343 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
344 | if (err < 0) | |
345 | return err; | |
346 | ||
347 | /* | |
348 | * According to the DP 1.1 specification, a "Sink Device must exit the | |
349 | * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink | |
350 | * Control Field" (register 0x600). | |
351 | */ | |
352 | usleep_range(1000, 2000); | |
353 | ||
354 | return 0; | |
355 | } | |
356 | EXPORT_SYMBOL(drm_dp_link_power_up); | |
357 | ||
d816f077 RC |
358 | /** |
359 | * drm_dp_link_power_down() - power down a DisplayPort link | |
360 | * @aux: DisplayPort AUX channel | |
361 | * @link: pointer to a structure containing the link configuration | |
362 | * | |
363 | * Returns 0 on success or a negative error code on failure. | |
364 | */ | |
365 | int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
366 | { | |
367 | u8 value; | |
368 | int err; | |
369 | ||
370 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
371 | if (link->revision < 0x11) | |
372 | return 0; | |
373 | ||
374 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
375 | if (err < 0) | |
376 | return err; | |
377 | ||
378 | value &= ~DP_SET_POWER_MASK; | |
379 | value |= DP_SET_POWER_D3; | |
380 | ||
381 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
382 | if (err < 0) | |
383 | return err; | |
384 | ||
385 | return 0; | |
386 | } | |
387 | EXPORT_SYMBOL(drm_dp_link_power_down); | |
388 | ||
516c0f7c TR |
389 | /** |
390 | * drm_dp_link_configure() - configure a DisplayPort link | |
391 | * @aux: DisplayPort AUX channel | |
392 | * @link: pointer to a structure containing the link configuration | |
393 | * | |
394 | * Returns 0 on success or a negative error code on failure. | |
395 | */ | |
396 | int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
397 | { | |
398 | u8 values[2]; | |
399 | int err; | |
400 | ||
401 | values[0] = drm_dp_link_rate_to_bw_code(link->rate); | |
402 | values[1] = link->num_lanes; | |
403 | ||
404 | if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) | |
405 | values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; | |
406 | ||
407 | err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); | |
408 | if (err < 0) | |
409 | return err; | |
410 | ||
411 | return 0; | |
412 | } | |
413 | EXPORT_SYMBOL(drm_dp_link_configure); | |
88759686 TR |
414 | |
415 | /* | |
416 | * I2C-over-AUX implementation | |
417 | */ | |
418 | ||
419 | static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter) | |
420 | { | |
421 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | | |
422 | I2C_FUNC_SMBUS_READ_BLOCK_DATA | | |
423 | I2C_FUNC_SMBUS_BLOCK_PROC_CALL | | |
424 | I2C_FUNC_10BIT_ADDR; | |
425 | } | |
426 | ||
4efa83c8 VS |
427 | #define AUX_PRECHARGE_LEN 10 /* 10 to 16 */ |
428 | #define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */ | |
429 | #define AUX_STOP_LEN 4 | |
430 | #define AUX_CMD_LEN 4 | |
431 | #define AUX_ADDRESS_LEN 20 | |
432 | #define AUX_REPLY_PAD_LEN 4 | |
433 | #define AUX_LENGTH_LEN 8 | |
434 | ||
435 | /* | |
436 | * Calculate the duration of the AUX request/reply in usec. Gives the | |
437 | * "best" case estimate, ie. successful while as short as possible. | |
438 | */ | |
439 | static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg *msg) | |
440 | { | |
441 | int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + | |
442 | AUX_CMD_LEN + AUX_ADDRESS_LEN + AUX_LENGTH_LEN; | |
443 | ||
444 | if ((msg->request & DP_AUX_I2C_READ) == 0) | |
445 | len += msg->size * 8; | |
446 | ||
447 | return len; | |
448 | } | |
449 | ||
450 | static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg *msg) | |
451 | { | |
452 | int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + | |
453 | AUX_CMD_LEN + AUX_REPLY_PAD_LEN; | |
454 | ||
455 | /* | |
456 | * For read we expect what was asked. For writes there will | |
457 | * be 0 or 1 data bytes. Assume 0 for the "best" case. | |
458 | */ | |
459 | if (msg->request & DP_AUX_I2C_READ) | |
460 | len += msg->size * 8; | |
461 | ||
462 | return len; | |
463 | } | |
464 | ||
465 | #define I2C_START_LEN 1 | |
466 | #define I2C_STOP_LEN 1 | |
467 | #define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */ | |
468 | #define I2C_DATA_LEN 9 /* DATA + ACK/NACK */ | |
469 | ||
470 | /* | |
471 | * Calculate the length of the i2c transfer in usec, assuming | |
472 | * the i2c bus speed is as specified. Gives the the "worst" | |
473 | * case estimate, ie. successful while as long as possible. | |
474 | * Doesn't account the the "MOT" bit, and instead assumes each | |
475 | * message includes a START, ADDRESS and STOP. Neither does it | |
476 | * account for additional random variables such as clock stretching. | |
477 | */ | |
478 | static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg *msg, | |
479 | int i2c_speed_khz) | |
480 | { | |
481 | /* AUX bitrate is 1MHz, i2c bitrate as specified */ | |
482 | return DIV_ROUND_UP((I2C_START_LEN + I2C_ADDR_LEN + | |
483 | msg->size * I2C_DATA_LEN + | |
484 | I2C_STOP_LEN) * 1000, i2c_speed_khz); | |
485 | } | |
486 | ||
487 | /* | |
488 | * Deterine how many retries should be attempted to successfully transfer | |
489 | * the specified message, based on the estimated durations of the | |
490 | * i2c and AUX transfers. | |
491 | */ | |
492 | static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg, | |
493 | int i2c_speed_khz) | |
494 | { | |
495 | int aux_time_us = drm_dp_aux_req_duration(msg) + | |
496 | drm_dp_aux_reply_duration(msg); | |
497 | int i2c_time_us = drm_dp_i2c_msg_duration(msg, i2c_speed_khz); | |
498 | ||
499 | return DIV_ROUND_UP(i2c_time_us, aux_time_us + AUX_RETRY_INTERVAL); | |
500 | } | |
501 | ||
f36203be VS |
502 | /* |
503 | * FIXME currently assumes 10 kHz as some real world devices seem | |
504 | * to require it. We should query/set the speed via DPCD if supported. | |
505 | */ | |
506 | static int dp_aux_i2c_speed_khz __read_mostly = 10; | |
507 | module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644); | |
508 | MODULE_PARM_DESC(dp_aux_i2c_speed_khz, | |
509 | "Assumed speed of the i2c bus in kHz, (1-400, default 10)"); | |
510 | ||
88759686 TR |
511 | /* |
512 | * Transfer a single I2C-over-AUX message and handle various error conditions, | |
732d50b4 AD |
513 | * retrying the transaction as appropriate. It is assumed that the |
514 | * aux->transfer function does not modify anything in the msg other than the | |
515 | * reply field. | |
1d002fa7 SF |
516 | * |
517 | * Returns bytes transferred on success, or a negative error code on failure. | |
88759686 TR |
518 | */ |
519 | static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) | |
520 | { | |
396aa445 | 521 | unsigned int retry, defer_i2c; |
1d002fa7 | 522 | int ret; |
88759686 TR |
523 | /* |
524 | * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device | |
525 | * is required to retry at least seven times upon receiving AUX_DEFER | |
526 | * before giving up the AUX transaction. | |
4efa83c8 VS |
527 | * |
528 | * We also try to account for the i2c bus speed. | |
88759686 | 529 | */ |
f36203be | 530 | int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz)); |
4efa83c8 VS |
531 | |
532 | for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) { | |
4f71d0cb | 533 | mutex_lock(&aux->hw_mutex); |
1d002fa7 | 534 | ret = aux->transfer(aux, msg); |
4f71d0cb | 535 | mutex_unlock(&aux->hw_mutex); |
1d002fa7 SF |
536 | if (ret < 0) { |
537 | if (ret == -EBUSY) | |
88759686 TR |
538 | continue; |
539 | ||
1d002fa7 SF |
540 | DRM_DEBUG_KMS("transaction failed: %d\n", ret); |
541 | return ret; | |
88759686 TR |
542 | } |
543 | ||
88759686 TR |
544 | |
545 | switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) { | |
546 | case DP_AUX_NATIVE_REPLY_ACK: | |
547 | /* | |
548 | * For I2C-over-AUX transactions this isn't enough, we | |
549 | * need to check for the I2C ACK reply. | |
550 | */ | |
551 | break; | |
552 | ||
553 | case DP_AUX_NATIVE_REPLY_NACK: | |
fb8c5e49 | 554 | DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size); |
88759686 TR |
555 | return -EREMOTEIO; |
556 | ||
557 | case DP_AUX_NATIVE_REPLY_DEFER: | |
747552b9 | 558 | DRM_DEBUG_KMS("native defer\n"); |
88759686 TR |
559 | /* |
560 | * We could check for I2C bit rate capabilities and if | |
561 | * available adjust this interval. We could also be | |
562 | * more careful with DP-to-legacy adapters where a | |
563 | * long legacy cable may force very low I2C bit rates. | |
564 | * | |
565 | * For now just defer for long enough to hopefully be | |
566 | * safe for all use-cases. | |
567 | */ | |
79a2b161 | 568 | usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); |
88759686 TR |
569 | continue; |
570 | ||
571 | default: | |
572 | DRM_ERROR("invalid native reply %#04x\n", msg->reply); | |
573 | return -EREMOTEIO; | |
574 | } | |
575 | ||
576 | switch (msg->reply & DP_AUX_I2C_REPLY_MASK) { | |
577 | case DP_AUX_I2C_REPLY_ACK: | |
578 | /* | |
579 | * Both native ACK and I2C ACK replies received. We | |
580 | * can assume the transfer was successful. | |
581 | */ | |
1d002fa7 | 582 | return ret; |
88759686 TR |
583 | |
584 | case DP_AUX_I2C_REPLY_NACK: | |
fb8c5e49 | 585 | DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size); |
e9cf6194 | 586 | aux->i2c_nack_count++; |
88759686 TR |
587 | return -EREMOTEIO; |
588 | ||
589 | case DP_AUX_I2C_REPLY_DEFER: | |
590 | DRM_DEBUG_KMS("I2C defer\n"); | |
396aa445 TP |
591 | /* DP Compliance Test 4.2.2.5 Requirement: |
592 | * Must have at least 7 retries for I2C defers on the | |
593 | * transaction to pass this test | |
594 | */ | |
e9cf6194 | 595 | aux->i2c_defer_count++; |
396aa445 TP |
596 | if (defer_i2c < 7) |
597 | defer_i2c++; | |
79a2b161 | 598 | usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); |
88759686 TR |
599 | continue; |
600 | ||
601 | default: | |
602 | DRM_ERROR("invalid I2C reply %#04x\n", msg->reply); | |
603 | return -EREMOTEIO; | |
604 | } | |
605 | } | |
606 | ||
743b1e32 | 607 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
88759686 TR |
608 | return -EREMOTEIO; |
609 | } | |
610 | ||
1d002fa7 SF |
611 | /* |
612 | * Keep retrying drm_dp_i2c_do_msg until all data has been transferred. | |
613 | * | |
614 | * Returns an error code on failure, or a recommended transfer size on success. | |
615 | */ | |
616 | static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg) | |
617 | { | |
618 | int err, ret = orig_msg->size; | |
619 | struct drm_dp_aux_msg msg = *orig_msg; | |
620 | ||
621 | while (msg.size > 0) { | |
622 | err = drm_dp_i2c_do_msg(aux, &msg); | |
623 | if (err <= 0) | |
624 | return err == 0 ? -EPROTO : err; | |
625 | ||
626 | if (err < msg.size && err < ret) { | |
627 | DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n", | |
628 | msg.size, err); | |
629 | ret = err; | |
630 | } | |
631 | ||
632 | msg.size -= err; | |
633 | msg.buffer += err; | |
634 | } | |
635 | ||
636 | return ret; | |
637 | } | |
638 | ||
639 | /* | |
640 | * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX | |
641 | * packets to be as large as possible. If not, the I2C transactions never | |
642 | * succeed. Hence the default is maximum. | |
643 | */ | |
644 | static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES; | |
645 | module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644); | |
646 | MODULE_PARM_DESC(dp_aux_i2c_transfer_size, | |
647 | "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)"); | |
648 | ||
88759686 TR |
649 | static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, |
650 | int num) | |
651 | { | |
652 | struct drm_dp_aux *aux = adapter->algo_data; | |
653 | unsigned int i, j; | |
1d002fa7 | 654 | unsigned transfer_size; |
ccdb516e AD |
655 | struct drm_dp_aux_msg msg; |
656 | int err = 0; | |
88759686 | 657 | |
1d002fa7 SF |
658 | dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES); |
659 | ||
ccdb516e | 660 | memset(&msg, 0, sizeof(msg)); |
88759686 | 661 | |
ccdb516e AD |
662 | for (i = 0; i < num; i++) { |
663 | msg.address = msgs[i].addr; | |
664 | msg.request = (msgs[i].flags & I2C_M_RD) ? | |
665 | DP_AUX_I2C_READ : | |
666 | DP_AUX_I2C_WRITE; | |
667 | msg.request |= DP_AUX_I2C_MOT; | |
668 | /* Send a bare address packet to start the transaction. | |
669 | * Zero sized messages specify an address only (bare | |
670 | * address) transaction. | |
671 | */ | |
672 | msg.buffer = NULL; | |
673 | msg.size = 0; | |
674 | err = drm_dp_i2c_do_msg(aux, &msg); | |
675 | if (err < 0) | |
676 | break; | |
1d002fa7 SF |
677 | /* We want each transaction to be as large as possible, but |
678 | * we'll go to smaller sizes if the hardware gives us a | |
679 | * short reply. | |
88759686 | 680 | */ |
1d002fa7 SF |
681 | transfer_size = dp_aux_i2c_transfer_size; |
682 | for (j = 0; j < msgs[i].len; j += msg.size) { | |
88759686 | 683 | msg.buffer = msgs[i].buf + j; |
1d002fa7 | 684 | msg.size = min(transfer_size, msgs[i].len - j); |
88759686 | 685 | |
1d002fa7 | 686 | err = drm_dp_i2c_drain_msg(aux, &msg); |
88759686 | 687 | if (err < 0) |
ccdb516e | 688 | break; |
1d002fa7 | 689 | transfer_size = err; |
88759686 | 690 | } |
ccdb516e AD |
691 | if (err < 0) |
692 | break; | |
88759686 | 693 | } |
ccdb516e AD |
694 | if (err >= 0) |
695 | err = num; | |
696 | /* Send a bare address packet to close out the transaction. | |
697 | * Zero sized messages specify an address only (bare | |
698 | * address) transaction. | |
699 | */ | |
700 | msg.request &= ~DP_AUX_I2C_MOT; | |
701 | msg.buffer = NULL; | |
702 | msg.size = 0; | |
703 | (void)drm_dp_i2c_do_msg(aux, &msg); | |
88759686 | 704 | |
ccdb516e | 705 | return err; |
88759686 TR |
706 | } |
707 | ||
708 | static const struct i2c_algorithm drm_dp_i2c_algo = { | |
709 | .functionality = drm_dp_i2c_functionality, | |
710 | .master_xfer = drm_dp_i2c_xfer, | |
711 | }; | |
712 | ||
713 | /** | |
4f71d0cb | 714 | * drm_dp_aux_register() - initialise and register aux channel |
88759686 TR |
715 | * @aux: DisplayPort AUX channel |
716 | * | |
717 | * Returns 0 on success or a negative error code on failure. | |
718 | */ | |
4f71d0cb | 719 | int drm_dp_aux_register(struct drm_dp_aux *aux) |
88759686 | 720 | { |
4f71d0cb DA |
721 | mutex_init(&aux->hw_mutex); |
722 | ||
88759686 TR |
723 | aux->ddc.algo = &drm_dp_i2c_algo; |
724 | aux->ddc.algo_data = aux; | |
725 | aux->ddc.retries = 3; | |
726 | ||
727 | aux->ddc.class = I2C_CLASS_DDC; | |
728 | aux->ddc.owner = THIS_MODULE; | |
729 | aux->ddc.dev.parent = aux->dev; | |
730 | aux->ddc.dev.of_node = aux->dev->of_node; | |
731 | ||
9dc40560 JN |
732 | strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev), |
733 | sizeof(aux->ddc.name)); | |
88759686 TR |
734 | |
735 | return i2c_add_adapter(&aux->ddc); | |
736 | } | |
4f71d0cb | 737 | EXPORT_SYMBOL(drm_dp_aux_register); |
88759686 TR |
738 | |
739 | /** | |
4f71d0cb | 740 | * drm_dp_aux_unregister() - unregister an AUX adapter |
88759686 TR |
741 | * @aux: DisplayPort AUX channel |
742 | */ | |
4f71d0cb | 743 | void drm_dp_aux_unregister(struct drm_dp_aux *aux) |
88759686 TR |
744 | { |
745 | i2c_del_adapter(&aux->ddc); | |
746 | } | |
4f71d0cb | 747 | EXPORT_SYMBOL(drm_dp_aux_unregister); |