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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 | 30 | #include <drm/drm_dp_helper.h> |
e94cb37b | 31 | #include <drm/drm_dp_aux_dev.h> |
760285e7 | 32 | #include <drm/drmP.h> |
a4fc5ed6 | 33 | |
28164fda DV |
34 | /** |
35 | * DOC: dp helpers | |
36 | * | |
37 | * These functions contain some common logic and helpers at various abstraction | |
38 | * levels to deal with Display Port sink devices and related things like DP aux | |
39 | * channel transfers, EDID reading over DP aux channels, decoding certain DPCD | |
40 | * blocks, ... | |
41 | */ | |
42 | ||
1ffdff13 | 43 | /* Helpers for DP link training */ |
0aec2881 | 44 | static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r) |
1ffdff13 DV |
45 | { |
46 | return link_status[r - DP_LANE0_1_STATUS]; | |
47 | } | |
48 | ||
0aec2881 | 49 | static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
50 | int lane) |
51 | { | |
52 | int i = DP_LANE0_1_STATUS + (lane >> 1); | |
53 | int s = (lane & 1) * 4; | |
54 | u8 l = dp_link_status(link_status, i); | |
55 | return (l >> s) & 0xf; | |
56 | } | |
57 | ||
0aec2881 | 58 | bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
59 | int lane_count) |
60 | { | |
61 | u8 lane_align; | |
62 | u8 lane_status; | |
63 | int lane; | |
64 | ||
65 | lane_align = dp_link_status(link_status, | |
66 | DP_LANE_ALIGN_STATUS_UPDATED); | |
67 | if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0) | |
68 | return false; | |
69 | for (lane = 0; lane < lane_count; lane++) { | |
70 | lane_status = dp_get_lane_status(link_status, lane); | |
71 | if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS) | |
72 | return false; | |
73 | } | |
74 | return true; | |
75 | } | |
76 | EXPORT_SYMBOL(drm_dp_channel_eq_ok); | |
77 | ||
0aec2881 | 78 | bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE], |
1ffdff13 DV |
79 | int lane_count) |
80 | { | |
81 | int lane; | |
82 | u8 lane_status; | |
83 | ||
84 | for (lane = 0; lane < lane_count; lane++) { | |
85 | lane_status = dp_get_lane_status(link_status, lane); | |
86 | if ((lane_status & DP_LANE_CR_DONE) == 0) | |
87 | return false; | |
88 | } | |
89 | return true; | |
90 | } | |
91 | EXPORT_SYMBOL(drm_dp_clock_recovery_ok); | |
0f037bde | 92 | |
0aec2881 | 93 | u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE], |
0f037bde DV |
94 | int lane) |
95 | { | |
96 | int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); | |
97 | int s = ((lane & 1) ? | |
98 | DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT : | |
99 | DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT); | |
100 | u8 l = dp_link_status(link_status, i); | |
101 | ||
102 | return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT; | |
103 | } | |
104 | EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage); | |
105 | ||
0aec2881 | 106 | u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE], |
0f037bde DV |
107 | int lane) |
108 | { | |
109 | int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); | |
110 | int s = ((lane & 1) ? | |
111 | DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT : | |
112 | DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT); | |
113 | u8 l = dp_link_status(link_status, i); | |
114 | ||
115 | return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT; | |
116 | } | |
117 | EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis); | |
118 | ||
0aec2881 | 119 | void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { |
1a644cd4 DV |
120 | if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) |
121 | udelay(100); | |
122 | else | |
123 | mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); | |
124 | } | |
125 | EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay); | |
126 | ||
0aec2881 | 127 | void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { |
1a644cd4 DV |
128 | if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) |
129 | udelay(400); | |
130 | else | |
131 | mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); | |
132 | } | |
133 | EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay); | |
3b5c662e DV |
134 | |
135 | u8 drm_dp_link_rate_to_bw_code(int link_rate) | |
136 | { | |
137 | switch (link_rate) { | |
138 | case 162000: | |
139 | default: | |
140 | return DP_LINK_BW_1_62; | |
141 | case 270000: | |
142 | return DP_LINK_BW_2_7; | |
143 | case 540000: | |
144 | return DP_LINK_BW_5_4; | |
145 | } | |
146 | } | |
147 | EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code); | |
148 | ||
149 | int drm_dp_bw_code_to_link_rate(u8 link_bw) | |
150 | { | |
151 | switch (link_bw) { | |
152 | case DP_LINK_BW_1_62: | |
153 | default: | |
154 | return 162000; | |
155 | case DP_LINK_BW_2_7: | |
156 | return 270000; | |
157 | case DP_LINK_BW_5_4: | |
158 | return 540000; | |
159 | } | |
160 | } | |
161 | EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate); | |
c197db75 | 162 | |
79a2b161 VS |
163 | #define AUX_RETRY_INTERVAL 500 /* us */ |
164 | ||
c197db75 TR |
165 | /** |
166 | * DOC: dp helpers | |
167 | * | |
168 | * The DisplayPort AUX channel is an abstraction to allow generic, driver- | |
169 | * independent access to AUX functionality. Drivers can take advantage of | |
170 | * this by filling in the fields of the drm_dp_aux structure. | |
171 | * | |
172 | * Transactions are described using a hardware-independent drm_dp_aux_msg | |
173 | * structure, which is passed into a driver's .transfer() implementation. | |
174 | * Both native and I2C-over-AUX transactions are supported. | |
c197db75 TR |
175 | */ |
176 | ||
177 | static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, | |
178 | unsigned int offset, void *buffer, size_t size) | |
179 | { | |
180 | struct drm_dp_aux_msg msg; | |
82922da3 L |
181 | unsigned int retry, native_reply; |
182 | int err = 0, ret = 0; | |
c197db75 TR |
183 | |
184 | memset(&msg, 0, sizeof(msg)); | |
185 | msg.address = offset; | |
186 | msg.request = request; | |
187 | msg.buffer = buffer; | |
188 | msg.size = size; | |
189 | ||
7779c5e2 RC |
190 | mutex_lock(&aux->hw_mutex); |
191 | ||
c197db75 TR |
192 | /* |
193 | * The specification doesn't give any recommendation on how often to | |
19a93f04 DA |
194 | * retry native transactions. We used to retry 7 times like for |
195 | * aux i2c transactions but real world devices this wasn't | |
196 | * sufficient, bump to 32 which makes Dell 4k monitors happier. | |
c197db75 | 197 | */ |
19a93f04 | 198 | for (retry = 0; retry < 32; retry++) { |
82922da3 | 199 | if (ret != 0 && ret != -ETIMEDOUT) { |
e1083ff3 L |
200 | usleep_range(AUX_RETRY_INTERVAL, |
201 | AUX_RETRY_INTERVAL + 100); | |
202 | } | |
4f71d0cb | 203 | |
82922da3 | 204 | ret = aux->transfer(aux, &msg); |
c197db75 | 205 | |
82922da3 L |
206 | if (ret > 0) { |
207 | native_reply = msg.reply & DP_AUX_NATIVE_REPLY_MASK; | |
208 | if (native_reply == DP_AUX_NATIVE_REPLY_ACK) { | |
209 | if (ret == size) | |
210 | goto unlock; | |
c197db75 | 211 | |
82922da3 L |
212 | ret = -EPROTO; |
213 | } else | |
214 | ret = -EIO; | |
c197db75 | 215 | } |
82922da3 L |
216 | |
217 | /* | |
218 | * We want the error we return to be the error we received on | |
219 | * the first transaction, since we may get a different error the | |
220 | * next time we retry | |
221 | */ | |
222 | if (!err) | |
223 | err = ret; | |
c197db75 TR |
224 | } |
225 | ||
743b1e32 | 226 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
82922da3 | 227 | ret = err; |
7779c5e2 RC |
228 | |
229 | unlock: | |
230 | mutex_unlock(&aux->hw_mutex); | |
82922da3 | 231 | return ret; |
c197db75 TR |
232 | } |
233 | ||
234 | /** | |
235 | * drm_dp_dpcd_read() - read a series of bytes from the DPCD | |
236 | * @aux: DisplayPort AUX channel | |
237 | * @offset: address of the (first) register to read | |
238 | * @buffer: buffer to store the register values | |
239 | * @size: number of bytes in @buffer | |
240 | * | |
241 | * Returns the number of bytes transferred on success, or a negative error | |
242 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
243 | * if the retry count was exceeded. If not all bytes were transferred, this | |
244 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
245 | * function, with the exception of -EBUSY (which causes the transaction to | |
246 | * be retried), are propagated to the caller. | |
247 | */ | |
248 | ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, | |
249 | void *buffer, size_t size) | |
250 | { | |
f808f633 L |
251 | int ret; |
252 | ||
253 | /* | |
254 | * HP ZR24w corrupts the first DPCD access after entering power save | |
255 | * mode. Eg. on a read, the entire buffer will be filled with the same | |
256 | * byte. Do a throw away read to avoid corrupting anything we care | |
257 | * about. Afterwards things will work correctly until the monitor | |
258 | * gets woken up and subsequently re-enters power save mode. | |
259 | * | |
260 | * The user pressing any button on the monitor is enough to wake it | |
261 | * up, so there is no particularly good place to do the workaround. | |
262 | * We just have to do it before any DPCD access and hope that the | |
263 | * monitor doesn't power down exactly after the throw away read. | |
264 | */ | |
265 | ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer, | |
266 | 1); | |
267 | if (ret != 1) | |
268 | return ret; | |
269 | ||
c197db75 TR |
270 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, |
271 | size); | |
272 | } | |
273 | EXPORT_SYMBOL(drm_dp_dpcd_read); | |
274 | ||
275 | /** | |
276 | * drm_dp_dpcd_write() - write a series of bytes to the DPCD | |
277 | * @aux: DisplayPort AUX channel | |
278 | * @offset: address of the (first) register to write | |
279 | * @buffer: buffer containing the values to write | |
280 | * @size: number of bytes in @buffer | |
281 | * | |
282 | * Returns the number of bytes transferred on success, or a negative error | |
283 | * code on failure. -EIO is returned if the request was NAKed by the sink or | |
284 | * if the retry count was exceeded. If not all bytes were transferred, this | |
285 | * function returns -EPROTO. Errors from the underlying AUX channel transfer | |
286 | * function, with the exception of -EBUSY (which causes the transaction to | |
287 | * be retried), are propagated to the caller. | |
288 | */ | |
289 | ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, | |
290 | void *buffer, size_t size) | |
291 | { | |
292 | return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, | |
293 | size); | |
294 | } | |
295 | EXPORT_SYMBOL(drm_dp_dpcd_write); | |
8d4adc6a TR |
296 | |
297 | /** | |
298 | * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207) | |
299 | * @aux: DisplayPort AUX channel | |
300 | * @status: buffer to store the link status in (must be at least 6 bytes) | |
301 | * | |
302 | * Returns the number of bytes transferred on success or a negative error | |
303 | * code on failure. | |
304 | */ | |
305 | int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, | |
306 | u8 status[DP_LINK_STATUS_SIZE]) | |
307 | { | |
308 | return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status, | |
309 | DP_LINK_STATUS_SIZE); | |
310 | } | |
311 | EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); | |
516c0f7c TR |
312 | |
313 | /** | |
314 | * drm_dp_link_probe() - probe a DisplayPort link for capabilities | |
315 | * @aux: DisplayPort AUX channel | |
316 | * @link: pointer to structure in which to return link capabilities | |
317 | * | |
318 | * The structure filled in by this function can usually be passed directly | |
319 | * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and | |
320 | * configure the link based on the link's capabilities. | |
321 | * | |
322 | * Returns 0 on success or a negative error code on failure. | |
323 | */ | |
324 | int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
325 | { | |
326 | u8 values[3]; | |
327 | int err; | |
328 | ||
329 | memset(link, 0, sizeof(*link)); | |
330 | ||
331 | err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); | |
332 | if (err < 0) | |
333 | return err; | |
334 | ||
335 | link->revision = values[0]; | |
336 | link->rate = drm_dp_bw_code_to_link_rate(values[1]); | |
337 | link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; | |
338 | ||
339 | if (values[2] & DP_ENHANCED_FRAME_CAP) | |
340 | link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; | |
341 | ||
342 | return 0; | |
343 | } | |
344 | EXPORT_SYMBOL(drm_dp_link_probe); | |
345 | ||
346 | /** | |
347 | * drm_dp_link_power_up() - power up a DisplayPort link | |
348 | * @aux: DisplayPort AUX channel | |
349 | * @link: pointer to a structure containing the link configuration | |
350 | * | |
351 | * Returns 0 on success or a negative error code on failure. | |
352 | */ | |
353 | int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
354 | { | |
355 | u8 value; | |
356 | int err; | |
357 | ||
358 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
359 | if (link->revision < 0x11) | |
360 | return 0; | |
361 | ||
362 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
363 | if (err < 0) | |
364 | return err; | |
365 | ||
366 | value &= ~DP_SET_POWER_MASK; | |
367 | value |= DP_SET_POWER_D0; | |
368 | ||
369 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
370 | if (err < 0) | |
371 | return err; | |
372 | ||
373 | /* | |
374 | * According to the DP 1.1 specification, a "Sink Device must exit the | |
375 | * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink | |
376 | * Control Field" (register 0x600). | |
377 | */ | |
378 | usleep_range(1000, 2000); | |
379 | ||
380 | return 0; | |
381 | } | |
382 | EXPORT_SYMBOL(drm_dp_link_power_up); | |
383 | ||
d816f077 RC |
384 | /** |
385 | * drm_dp_link_power_down() - power down a DisplayPort link | |
386 | * @aux: DisplayPort AUX channel | |
387 | * @link: pointer to a structure containing the link configuration | |
388 | * | |
389 | * Returns 0 on success or a negative error code on failure. | |
390 | */ | |
391 | int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
392 | { | |
393 | u8 value; | |
394 | int err; | |
395 | ||
396 | /* DP_SET_POWER register is only available on DPCD v1.1 and later */ | |
397 | if (link->revision < 0x11) | |
398 | return 0; | |
399 | ||
400 | err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); | |
401 | if (err < 0) | |
402 | return err; | |
403 | ||
404 | value &= ~DP_SET_POWER_MASK; | |
405 | value |= DP_SET_POWER_D3; | |
406 | ||
407 | err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); | |
408 | if (err < 0) | |
409 | return err; | |
410 | ||
411 | return 0; | |
412 | } | |
413 | EXPORT_SYMBOL(drm_dp_link_power_down); | |
414 | ||
516c0f7c TR |
415 | /** |
416 | * drm_dp_link_configure() - configure a DisplayPort link | |
417 | * @aux: DisplayPort AUX channel | |
418 | * @link: pointer to a structure containing the link configuration | |
419 | * | |
420 | * Returns 0 on success or a negative error code on failure. | |
421 | */ | |
422 | int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) | |
423 | { | |
424 | u8 values[2]; | |
425 | int err; | |
426 | ||
427 | values[0] = drm_dp_link_rate_to_bw_code(link->rate); | |
428 | values[1] = link->num_lanes; | |
429 | ||
430 | if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) | |
431 | values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; | |
432 | ||
433 | err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); | |
434 | if (err < 0) | |
435 | return err; | |
436 | ||
437 | return 0; | |
438 | } | |
439 | EXPORT_SYMBOL(drm_dp_link_configure); | |
88759686 TR |
440 | |
441 | /* | |
442 | * I2C-over-AUX implementation | |
443 | */ | |
444 | ||
445 | static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter) | |
446 | { | |
447 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | | |
448 | I2C_FUNC_SMBUS_READ_BLOCK_DATA | | |
449 | I2C_FUNC_SMBUS_BLOCK_PROC_CALL | | |
450 | I2C_FUNC_10BIT_ADDR; | |
451 | } | |
452 | ||
68ec2a2a VS |
453 | static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg) |
454 | { | |
455 | /* | |
456 | * In case of i2c defer or short i2c ack reply to a write, | |
457 | * we need to switch to WRITE_STATUS_UPDATE to drain the | |
458 | * rest of the message | |
459 | */ | |
460 | if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE) { | |
461 | msg->request &= DP_AUX_I2C_MOT; | |
462 | msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE; | |
463 | } | |
464 | } | |
465 | ||
4efa83c8 VS |
466 | #define AUX_PRECHARGE_LEN 10 /* 10 to 16 */ |
467 | #define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */ | |
468 | #define AUX_STOP_LEN 4 | |
469 | #define AUX_CMD_LEN 4 | |
470 | #define AUX_ADDRESS_LEN 20 | |
471 | #define AUX_REPLY_PAD_LEN 4 | |
472 | #define AUX_LENGTH_LEN 8 | |
473 | ||
474 | /* | |
475 | * Calculate the duration of the AUX request/reply in usec. Gives the | |
476 | * "best" case estimate, ie. successful while as short as possible. | |
477 | */ | |
478 | static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg *msg) | |
479 | { | |
480 | int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + | |
481 | AUX_CMD_LEN + AUX_ADDRESS_LEN + AUX_LENGTH_LEN; | |
482 | ||
483 | if ((msg->request & DP_AUX_I2C_READ) == 0) | |
484 | len += msg->size * 8; | |
485 | ||
486 | return len; | |
487 | } | |
488 | ||
489 | static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg *msg) | |
490 | { | |
491 | int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + | |
492 | AUX_CMD_LEN + AUX_REPLY_PAD_LEN; | |
493 | ||
494 | /* | |
495 | * For read we expect what was asked. For writes there will | |
496 | * be 0 or 1 data bytes. Assume 0 for the "best" case. | |
497 | */ | |
498 | if (msg->request & DP_AUX_I2C_READ) | |
499 | len += msg->size * 8; | |
500 | ||
501 | return len; | |
502 | } | |
503 | ||
504 | #define I2C_START_LEN 1 | |
505 | #define I2C_STOP_LEN 1 | |
506 | #define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */ | |
507 | #define I2C_DATA_LEN 9 /* DATA + ACK/NACK */ | |
508 | ||
509 | /* | |
510 | * Calculate the length of the i2c transfer in usec, assuming | |
511 | * the i2c bus speed is as specified. Gives the the "worst" | |
512 | * case estimate, ie. successful while as long as possible. | |
513 | * Doesn't account the the "MOT" bit, and instead assumes each | |
514 | * message includes a START, ADDRESS and STOP. Neither does it | |
515 | * account for additional random variables such as clock stretching. | |
516 | */ | |
517 | static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg *msg, | |
518 | int i2c_speed_khz) | |
519 | { | |
520 | /* AUX bitrate is 1MHz, i2c bitrate as specified */ | |
521 | return DIV_ROUND_UP((I2C_START_LEN + I2C_ADDR_LEN + | |
522 | msg->size * I2C_DATA_LEN + | |
523 | I2C_STOP_LEN) * 1000, i2c_speed_khz); | |
524 | } | |
525 | ||
526 | /* | |
527 | * Deterine how many retries should be attempted to successfully transfer | |
528 | * the specified message, based on the estimated durations of the | |
529 | * i2c and AUX transfers. | |
530 | */ | |
531 | static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg, | |
532 | int i2c_speed_khz) | |
533 | { | |
534 | int aux_time_us = drm_dp_aux_req_duration(msg) + | |
535 | drm_dp_aux_reply_duration(msg); | |
536 | int i2c_time_us = drm_dp_i2c_msg_duration(msg, i2c_speed_khz); | |
537 | ||
538 | return DIV_ROUND_UP(i2c_time_us, aux_time_us + AUX_RETRY_INTERVAL); | |
539 | } | |
540 | ||
f36203be VS |
541 | /* |
542 | * FIXME currently assumes 10 kHz as some real world devices seem | |
543 | * to require it. We should query/set the speed via DPCD if supported. | |
544 | */ | |
545 | static int dp_aux_i2c_speed_khz __read_mostly = 10; | |
546 | module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644); | |
547 | MODULE_PARM_DESC(dp_aux_i2c_speed_khz, | |
548 | "Assumed speed of the i2c bus in kHz, (1-400, default 10)"); | |
549 | ||
88759686 TR |
550 | /* |
551 | * Transfer a single I2C-over-AUX message and handle various error conditions, | |
732d50b4 AD |
552 | * retrying the transaction as appropriate. It is assumed that the |
553 | * aux->transfer function does not modify anything in the msg other than the | |
554 | * reply field. | |
1d002fa7 SF |
555 | * |
556 | * Returns bytes transferred on success, or a negative error code on failure. | |
88759686 TR |
557 | */ |
558 | static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) | |
559 | { | |
396aa445 | 560 | unsigned int retry, defer_i2c; |
1d002fa7 | 561 | int ret; |
88759686 TR |
562 | /* |
563 | * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device | |
564 | * is required to retry at least seven times upon receiving AUX_DEFER | |
565 | * before giving up the AUX transaction. | |
4efa83c8 VS |
566 | * |
567 | * We also try to account for the i2c bus speed. | |
88759686 | 568 | */ |
f36203be | 569 | int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz)); |
4efa83c8 VS |
570 | |
571 | for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) { | |
1d002fa7 | 572 | ret = aux->transfer(aux, msg); |
1d002fa7 SF |
573 | if (ret < 0) { |
574 | if (ret == -EBUSY) | |
88759686 TR |
575 | continue; |
576 | ||
1d002fa7 SF |
577 | DRM_DEBUG_KMS("transaction failed: %d\n", ret); |
578 | return ret; | |
88759686 TR |
579 | } |
580 | ||
88759686 TR |
581 | |
582 | switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) { | |
583 | case DP_AUX_NATIVE_REPLY_ACK: | |
584 | /* | |
585 | * For I2C-over-AUX transactions this isn't enough, we | |
586 | * need to check for the I2C ACK reply. | |
587 | */ | |
588 | break; | |
589 | ||
590 | case DP_AUX_NATIVE_REPLY_NACK: | |
fb8c5e49 | 591 | DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size); |
88759686 TR |
592 | return -EREMOTEIO; |
593 | ||
594 | case DP_AUX_NATIVE_REPLY_DEFER: | |
747552b9 | 595 | DRM_DEBUG_KMS("native defer\n"); |
88759686 TR |
596 | /* |
597 | * We could check for I2C bit rate capabilities and if | |
598 | * available adjust this interval. We could also be | |
599 | * more careful with DP-to-legacy adapters where a | |
600 | * long legacy cable may force very low I2C bit rates. | |
601 | * | |
602 | * For now just defer for long enough to hopefully be | |
603 | * safe for all use-cases. | |
604 | */ | |
79a2b161 | 605 | usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); |
88759686 TR |
606 | continue; |
607 | ||
608 | default: | |
609 | DRM_ERROR("invalid native reply %#04x\n", msg->reply); | |
610 | return -EREMOTEIO; | |
611 | } | |
612 | ||
613 | switch (msg->reply & DP_AUX_I2C_REPLY_MASK) { | |
614 | case DP_AUX_I2C_REPLY_ACK: | |
615 | /* | |
616 | * Both native ACK and I2C ACK replies received. We | |
617 | * can assume the transfer was successful. | |
618 | */ | |
68ec2a2a VS |
619 | if (ret != msg->size) |
620 | drm_dp_i2c_msg_write_status_update(msg); | |
1d002fa7 | 621 | return ret; |
88759686 TR |
622 | |
623 | case DP_AUX_I2C_REPLY_NACK: | |
fb8c5e49 | 624 | DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size); |
e9cf6194 | 625 | aux->i2c_nack_count++; |
88759686 TR |
626 | return -EREMOTEIO; |
627 | ||
628 | case DP_AUX_I2C_REPLY_DEFER: | |
629 | DRM_DEBUG_KMS("I2C defer\n"); | |
396aa445 TP |
630 | /* DP Compliance Test 4.2.2.5 Requirement: |
631 | * Must have at least 7 retries for I2C defers on the | |
632 | * transaction to pass this test | |
633 | */ | |
e9cf6194 | 634 | aux->i2c_defer_count++; |
396aa445 TP |
635 | if (defer_i2c < 7) |
636 | defer_i2c++; | |
79a2b161 | 637 | usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); |
68ec2a2a | 638 | drm_dp_i2c_msg_write_status_update(msg); |
646db260 | 639 | |
88759686 TR |
640 | continue; |
641 | ||
642 | default: | |
643 | DRM_ERROR("invalid I2C reply %#04x\n", msg->reply); | |
644 | return -EREMOTEIO; | |
645 | } | |
646 | } | |
647 | ||
743b1e32 | 648 | DRM_DEBUG_KMS("too many retries, giving up\n"); |
88759686 TR |
649 | return -EREMOTEIO; |
650 | } | |
651 | ||
68ec2a2a VS |
652 | static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg, |
653 | const struct i2c_msg *i2c_msg) | |
654 | { | |
655 | msg->request = (i2c_msg->flags & I2C_M_RD) ? | |
656 | DP_AUX_I2C_READ : DP_AUX_I2C_WRITE; | |
657 | msg->request |= DP_AUX_I2C_MOT; | |
658 | } | |
659 | ||
1d002fa7 SF |
660 | /* |
661 | * Keep retrying drm_dp_i2c_do_msg until all data has been transferred. | |
662 | * | |
663 | * Returns an error code on failure, or a recommended transfer size on success. | |
664 | */ | |
665 | static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg) | |
666 | { | |
667 | int err, ret = orig_msg->size; | |
668 | struct drm_dp_aux_msg msg = *orig_msg; | |
669 | ||
670 | while (msg.size > 0) { | |
671 | err = drm_dp_i2c_do_msg(aux, &msg); | |
672 | if (err <= 0) | |
673 | return err == 0 ? -EPROTO : err; | |
674 | ||
675 | if (err < msg.size && err < ret) { | |
676 | DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n", | |
677 | msg.size, err); | |
678 | ret = err; | |
679 | } | |
680 | ||
681 | msg.size -= err; | |
682 | msg.buffer += err; | |
683 | } | |
684 | ||
685 | return ret; | |
686 | } | |
687 | ||
688 | /* | |
689 | * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX | |
690 | * packets to be as large as possible. If not, the I2C transactions never | |
691 | * succeed. Hence the default is maximum. | |
692 | */ | |
693 | static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES; | |
694 | module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644); | |
695 | MODULE_PARM_DESC(dp_aux_i2c_transfer_size, | |
696 | "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)"); | |
697 | ||
88759686 TR |
698 | static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, |
699 | int num) | |
700 | { | |
701 | struct drm_dp_aux *aux = adapter->algo_data; | |
702 | unsigned int i, j; | |
1d002fa7 | 703 | unsigned transfer_size; |
ccdb516e AD |
704 | struct drm_dp_aux_msg msg; |
705 | int err = 0; | |
88759686 | 706 | |
1d002fa7 SF |
707 | dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES); |
708 | ||
ccdb516e | 709 | memset(&msg, 0, sizeof(msg)); |
88759686 | 710 | |
7779c5e2 RC |
711 | mutex_lock(&aux->hw_mutex); |
712 | ||
ccdb516e AD |
713 | for (i = 0; i < num; i++) { |
714 | msg.address = msgs[i].addr; | |
68ec2a2a | 715 | drm_dp_i2c_msg_set_request(&msg, &msgs[i]); |
ccdb516e AD |
716 | /* Send a bare address packet to start the transaction. |
717 | * Zero sized messages specify an address only (bare | |
718 | * address) transaction. | |
719 | */ | |
720 | msg.buffer = NULL; | |
721 | msg.size = 0; | |
722 | err = drm_dp_i2c_do_msg(aux, &msg); | |
68ec2a2a VS |
723 | |
724 | /* | |
725 | * Reset msg.request in case in case it got | |
726 | * changed into a WRITE_STATUS_UPDATE. | |
727 | */ | |
728 | drm_dp_i2c_msg_set_request(&msg, &msgs[i]); | |
729 | ||
ccdb516e AD |
730 | if (err < 0) |
731 | break; | |
1d002fa7 SF |
732 | /* We want each transaction to be as large as possible, but |
733 | * we'll go to smaller sizes if the hardware gives us a | |
734 | * short reply. | |
88759686 | 735 | */ |
1d002fa7 SF |
736 | transfer_size = dp_aux_i2c_transfer_size; |
737 | for (j = 0; j < msgs[i].len; j += msg.size) { | |
88759686 | 738 | msg.buffer = msgs[i].buf + j; |
1d002fa7 | 739 | msg.size = min(transfer_size, msgs[i].len - j); |
88759686 | 740 | |
1d002fa7 | 741 | err = drm_dp_i2c_drain_msg(aux, &msg); |
68ec2a2a VS |
742 | |
743 | /* | |
744 | * Reset msg.request in case in case it got | |
745 | * changed into a WRITE_STATUS_UPDATE. | |
746 | */ | |
747 | drm_dp_i2c_msg_set_request(&msg, &msgs[i]); | |
748 | ||
88759686 | 749 | if (err < 0) |
ccdb516e | 750 | break; |
1d002fa7 | 751 | transfer_size = err; |
88759686 | 752 | } |
ccdb516e AD |
753 | if (err < 0) |
754 | break; | |
88759686 | 755 | } |
ccdb516e AD |
756 | if (err >= 0) |
757 | err = num; | |
758 | /* Send a bare address packet to close out the transaction. | |
759 | * Zero sized messages specify an address only (bare | |
760 | * address) transaction. | |
761 | */ | |
762 | msg.request &= ~DP_AUX_I2C_MOT; | |
763 | msg.buffer = NULL; | |
764 | msg.size = 0; | |
765 | (void)drm_dp_i2c_do_msg(aux, &msg); | |
88759686 | 766 | |
7779c5e2 RC |
767 | mutex_unlock(&aux->hw_mutex); |
768 | ||
ccdb516e | 769 | return err; |
88759686 TR |
770 | } |
771 | ||
772 | static const struct i2c_algorithm drm_dp_i2c_algo = { | |
773 | .functionality = drm_dp_i2c_functionality, | |
774 | .master_xfer = drm_dp_i2c_xfer, | |
775 | }; | |
776 | ||
777 | /** | |
4f71d0cb | 778 | * drm_dp_aux_register() - initialise and register aux channel |
88759686 TR |
779 | * @aux: DisplayPort AUX channel |
780 | * | |
781 | * Returns 0 on success or a negative error code on failure. | |
782 | */ | |
4f71d0cb | 783 | int drm_dp_aux_register(struct drm_dp_aux *aux) |
88759686 | 784 | { |
e94cb37b RA |
785 | int ret; |
786 | ||
4f71d0cb DA |
787 | mutex_init(&aux->hw_mutex); |
788 | ||
88759686 TR |
789 | aux->ddc.algo = &drm_dp_i2c_algo; |
790 | aux->ddc.algo_data = aux; | |
791 | aux->ddc.retries = 3; | |
792 | ||
793 | aux->ddc.class = I2C_CLASS_DDC; | |
794 | aux->ddc.owner = THIS_MODULE; | |
795 | aux->ddc.dev.parent = aux->dev; | |
796 | aux->ddc.dev.of_node = aux->dev->of_node; | |
797 | ||
9dc40560 JN |
798 | strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev), |
799 | sizeof(aux->ddc.name)); | |
88759686 | 800 | |
e94cb37b RA |
801 | ret = drm_dp_aux_register_devnode(aux); |
802 | if (ret) | |
803 | return ret; | |
804 | ||
805 | ret = i2c_add_adapter(&aux->ddc); | |
806 | if (ret) { | |
807 | drm_dp_aux_unregister_devnode(aux); | |
808 | return ret; | |
809 | } | |
810 | ||
811 | return 0; | |
88759686 | 812 | } |
4f71d0cb | 813 | EXPORT_SYMBOL(drm_dp_aux_register); |
88759686 TR |
814 | |
815 | /** | |
4f71d0cb | 816 | * drm_dp_aux_unregister() - unregister an AUX adapter |
88759686 TR |
817 | * @aux: DisplayPort AUX channel |
818 | */ | |
4f71d0cb | 819 | void drm_dp_aux_unregister(struct drm_dp_aux *aux) |
88759686 | 820 | { |
e94cb37b | 821 | drm_dp_aux_unregister_devnode(aux); |
88759686 TR |
822 | i2c_del_adapter(&aux->ddc); |
823 | } | |
4f71d0cb | 824 | EXPORT_SYMBOL(drm_dp_aux_unregister); |