Hans Verkuil | 1d4cf02 | 2018-07-11 15:29:07 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * DisplayPort CEC-Tunneling-over-AUX support |
| 4 | * |
| 5 | * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved. |
| 6 | */ |
| 7 | |
| 8 | #include <linux/kernel.h> |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/slab.h> |
| 11 | #include <drm/drm_dp_helper.h> |
| 12 | #include <media/cec.h> |
| 13 | |
| 14 | /* |
| 15 | * Unfortunately it turns out that we have a chicken-and-egg situation |
| 16 | * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters |
| 17 | * have a converter chip that supports CEC-Tunneling-over-AUX (usually the |
| 18 | * Parade PS176), but they do not wire up the CEC pin, thus making CEC |
| 19 | * useless. |
| 20 | * |
| 21 | * Sadly there is no way for this driver to know this. What happens is |
| 22 | * that a /dev/cecX device is created that is isolated and unable to see |
| 23 | * any of the other CEC devices. Quite literally the CEC wire is cut |
| 24 | * (or in this case, never connected in the first place). |
| 25 | * |
| 26 | * The reason so few adapters support this is that this tunneling protocol |
| 27 | * was never supported by any OS. So there was no easy way of testing it, |
| 28 | * and no incentive to correctly wire up the CEC pin. |
| 29 | * |
| 30 | * Hopefully by creating this driver it will be easier for vendors to |
| 31 | * finally fix their adapters and test the CEC functionality. |
| 32 | * |
| 33 | * I keep a list of known working adapters here: |
| 34 | * |
| 35 | * https://hverkuil.home.xs4all.nl/cec-status.txt |
| 36 | * |
| 37 | * Please mail me (hverkuil@xs4all.nl) if you find an adapter that works |
| 38 | * and is not yet listed there. |
| 39 | * |
| 40 | * Note that the current implementation does not support CEC over an MST hub. |
| 41 | * As far as I can see there is no mechanism defined in the DisplayPort |
| 42 | * standard to transport CEC interrupts over an MST device. It might be |
| 43 | * possible to do this through polling, but I have not been able to get that |
| 44 | * to work. |
| 45 | */ |
| 46 | |
| 47 | /** |
| 48 | * DOC: dp cec helpers |
| 49 | * |
| 50 | * These functions take care of supporting the CEC-Tunneling-over-AUX |
| 51 | * feature of DisplayPort-to-HDMI adapters. |
| 52 | */ |
| 53 | |
| 54 | /* |
| 55 | * When the EDID is unset because the HPD went low, then the CEC DPCD registers |
| 56 | * typically can no longer be read (true for a DP-to-HDMI adapter since it is |
| 57 | * powered by the HPD). However, some displays toggle the HPD off and on for a |
| 58 | * short period for one reason or another, and that would cause the CEC adapter |
| 59 | * to be removed and added again, even though nothing else changed. |
| 60 | * |
| 61 | * This module parameter sets a delay in seconds before the CEC adapter is |
| 62 | * actually unregistered. Only if the HPD does not return within that time will |
| 63 | * the CEC adapter be unregistered. |
| 64 | * |
| 65 | * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never |
| 66 | * be unregistered for as long as the connector remains registered. |
| 67 | * |
| 68 | * If it is set to 0, then the CEC adapter will be unregistered immediately as |
| 69 | * soon as the HPD disappears. |
| 70 | * |
| 71 | * The default is one second to prevent short HPD glitches from unregistering |
| 72 | * the CEC adapter. |
| 73 | * |
| 74 | * Note that for integrated HDMI branch devices that support CEC the DPCD |
| 75 | * registers remain available even if the HPD goes low since it is not powered |
| 76 | * by the HPD. In that case the CEC adapter will never be unregistered during |
| 77 | * the life time of the connector. At least, this is the theory since I do not |
| 78 | * have hardware with an integrated HDMI branch device that supports CEC. |
| 79 | */ |
| 80 | #define NEVER_UNREG_DELAY 1000 |
| 81 | static unsigned int drm_dp_cec_unregister_delay = 1; |
| 82 | module_param(drm_dp_cec_unregister_delay, uint, 0600); |
| 83 | MODULE_PARM_DESC(drm_dp_cec_unregister_delay, |
| 84 | "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister"); |
| 85 | |
| 86 | static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable) |
| 87 | { |
| 88 | struct drm_dp_aux *aux = cec_get_drvdata(adap); |
| 89 | u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0; |
| 90 | ssize_t err = 0; |
| 91 | |
| 92 | err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); |
| 93 | return (enable && err < 0) ? err : 0; |
| 94 | } |
| 95 | |
| 96 | static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr) |
| 97 | { |
| 98 | struct drm_dp_aux *aux = cec_get_drvdata(adap); |
| 99 | /* Bit 15 (logical address 15) should always be set */ |
| 100 | u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST; |
| 101 | u8 mask[2]; |
| 102 | ssize_t err; |
| 103 | |
| 104 | if (addr != CEC_LOG_ADDR_INVALID) |
| 105 | la_mask |= adap->log_addrs.log_addr_mask | (1 << addr); |
| 106 | mask[0] = la_mask & 0xff; |
| 107 | mask[1] = la_mask >> 8; |
| 108 | err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2); |
| 109 | return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0; |
| 110 | } |
| 111 | |
| 112 | static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, |
| 113 | u32 signal_free_time, struct cec_msg *msg) |
| 114 | { |
| 115 | struct drm_dp_aux *aux = cec_get_drvdata(adap); |
| 116 | unsigned int retries = min(5, attempts - 1); |
| 117 | ssize_t err; |
| 118 | |
| 119 | err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER, |
| 120 | msg->msg, msg->len); |
| 121 | if (err < 0) |
| 122 | return err; |
| 123 | |
| 124 | err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO, |
| 125 | (msg->len - 1) | (retries << 4) | |
| 126 | DP_CEC_TX_MESSAGE_SEND); |
| 127 | return err < 0 ? err : 0; |
| 128 | } |
| 129 | |
| 130 | static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap, |
| 131 | bool enable) |
| 132 | { |
| 133 | struct drm_dp_aux *aux = cec_get_drvdata(adap); |
| 134 | ssize_t err; |
| 135 | u8 val; |
| 136 | |
| 137 | if (!(adap->capabilities & CEC_CAP_MONITOR_ALL)) |
| 138 | return 0; |
| 139 | |
| 140 | err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val); |
| 141 | if (err >= 0) { |
| 142 | if (enable) |
| 143 | val |= DP_CEC_SNOOPING_ENABLE; |
| 144 | else |
| 145 | val &= ~DP_CEC_SNOOPING_ENABLE; |
| 146 | err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); |
| 147 | } |
| 148 | return (enable && err < 0) ? err : 0; |
| 149 | } |
| 150 | |
| 151 | static void drm_dp_cec_adap_status(struct cec_adapter *adap, |
| 152 | struct seq_file *file) |
| 153 | { |
| 154 | struct drm_dp_aux *aux = cec_get_drvdata(adap); |
| 155 | struct drm_dp_desc desc; |
| 156 | struct drm_dp_dpcd_ident *id = &desc.ident; |
| 157 | |
| 158 | if (drm_dp_read_desc(aux, &desc, true)) |
| 159 | return; |
| 160 | seq_printf(file, "OUI: %*pdH\n", |
| 161 | (int)sizeof(id->oui), id->oui); |
| 162 | seq_printf(file, "ID: %*pE\n", |
| 163 | (int)strnlen(id->device_id, sizeof(id->device_id)), |
| 164 | id->device_id); |
| 165 | seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf); |
| 166 | /* |
| 167 | * Show this both in decimal and hex: at least one vendor |
| 168 | * always reports this in hex. |
| 169 | */ |
| 170 | seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n", |
| 171 | id->sw_major_rev, id->sw_minor_rev, |
| 172 | id->sw_major_rev, id->sw_minor_rev); |
| 173 | } |
| 174 | |
| 175 | static const struct cec_adap_ops drm_dp_cec_adap_ops = { |
| 176 | .adap_enable = drm_dp_cec_adap_enable, |
| 177 | .adap_log_addr = drm_dp_cec_adap_log_addr, |
| 178 | .adap_transmit = drm_dp_cec_adap_transmit, |
| 179 | .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable, |
| 180 | .adap_status = drm_dp_cec_adap_status, |
| 181 | }; |
| 182 | |
| 183 | static int drm_dp_cec_received(struct drm_dp_aux *aux) |
| 184 | { |
| 185 | struct cec_adapter *adap = aux->cec.adap; |
| 186 | struct cec_msg msg; |
| 187 | u8 rx_msg_info; |
| 188 | ssize_t err; |
| 189 | |
| 190 | err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info); |
| 191 | if (err < 0) |
| 192 | return err; |
| 193 | |
| 194 | if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED)) |
| 195 | return 0; |
| 196 | |
| 197 | msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1; |
| 198 | err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len); |
| 199 | if (err < 0) |
| 200 | return err; |
| 201 | |
| 202 | cec_received_msg(adap, &msg); |
| 203 | return 0; |
| 204 | } |
| 205 | |
| 206 | static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux) |
| 207 | { |
| 208 | struct cec_adapter *adap = aux->cec.adap; |
| 209 | u8 flags; |
| 210 | |
| 211 | if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0) |
| 212 | return; |
| 213 | |
| 214 | if (flags & DP_CEC_RX_MESSAGE_INFO_VALID) |
| 215 | drm_dp_cec_received(aux); |
| 216 | |
| 217 | if (flags & DP_CEC_TX_MESSAGE_SENT) |
| 218 | cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK); |
| 219 | else if (flags & DP_CEC_TX_LINE_ERROR) |
| 220 | cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR | |
| 221 | CEC_TX_STATUS_MAX_RETRIES); |
| 222 | else if (flags & |
| 223 | (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR)) |
| 224 | cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK | |
| 225 | CEC_TX_STATUS_MAX_RETRIES); |
| 226 | drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags); |
| 227 | } |
| 228 | |
| 229 | /** |
| 230 | * drm_dp_cec_irq() - handle CEC interrupt, if any |
| 231 | * @aux: DisplayPort AUX channel |
| 232 | * |
| 233 | * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX |
| 234 | * is present, then it will check for a CEC_IRQ and handle it accordingly. |
| 235 | */ |
| 236 | void drm_dp_cec_irq(struct drm_dp_aux *aux) |
| 237 | { |
| 238 | u8 cec_irq; |
| 239 | int ret; |
| 240 | |
| 241 | mutex_lock(&aux->cec.lock); |
| 242 | if (!aux->cec.adap) |
| 243 | goto unlock; |
| 244 | |
| 245 | ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, |
| 246 | &cec_irq); |
| 247 | if (ret < 0 || !(cec_irq & DP_CEC_IRQ)) |
| 248 | goto unlock; |
| 249 | |
| 250 | drm_dp_cec_handle_irq(aux); |
| 251 | drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ); |
| 252 | unlock: |
| 253 | mutex_unlock(&aux->cec.lock); |
| 254 | } |
| 255 | EXPORT_SYMBOL(drm_dp_cec_irq); |
| 256 | |
| 257 | static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap) |
| 258 | { |
| 259 | u8 cap = 0; |
| 260 | |
| 261 | if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 || |
| 262 | !(cap & DP_CEC_TUNNELING_CAPABLE)) |
| 263 | return false; |
| 264 | if (cec_cap) |
| 265 | *cec_cap = cap; |
| 266 | return true; |
| 267 | } |
| 268 | |
| 269 | /* |
| 270 | * Called if the HPD was low for more than drm_dp_cec_unregister_delay |
| 271 | * seconds. This unregisters the CEC adapter. |
| 272 | */ |
| 273 | static void drm_dp_cec_unregister_work(struct work_struct *work) |
| 274 | { |
| 275 | struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux, |
| 276 | cec.unregister_work.work); |
| 277 | |
| 278 | mutex_lock(&aux->cec.lock); |
| 279 | cec_unregister_adapter(aux->cec.adap); |
| 280 | aux->cec.adap = NULL; |
| 281 | mutex_unlock(&aux->cec.lock); |
| 282 | } |
| 283 | |
| 284 | /* |
| 285 | * A new EDID is set. If there is no CEC adapter, then create one. If |
| 286 | * there was a CEC adapter, then check if the CEC adapter properties |
| 287 | * were unchanged and just update the CEC physical address. Otherwise |
| 288 | * unregister the old CEC adapter and create a new one. |
| 289 | */ |
| 290 | void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid) |
| 291 | { |
Venkata Prahlad Valluru | 2db4fa0 | 2020-06-10 01:26:47 +0530 | [diff] [blame] | 292 | u32 cec_caps = CEC_CAP_DEFAULTS; |
Hans Verkuil | 1d4cf02 | 2018-07-11 15:29:07 +0200 | [diff] [blame] | 293 | unsigned int num_las = 1; |
| 294 | u8 cap; |
| 295 | |
| 296 | #ifndef CONFIG_MEDIA_CEC_RC |
| 297 | /* |
| 298 | * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by |
| 299 | * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined. |
| 300 | * |
| 301 | * Do this here as well to ensure the tests against cec_caps are |
| 302 | * correct. |
| 303 | */ |
| 304 | cec_caps &= ~CEC_CAP_RC; |
| 305 | #endif |
| 306 | cancel_delayed_work_sync(&aux->cec.unregister_work); |
| 307 | |
| 308 | mutex_lock(&aux->cec.lock); |
| 309 | if (!drm_dp_cec_cap(aux, &cap)) { |
| 310 | /* CEC is not supported, unregister any existing adapter */ |
| 311 | cec_unregister_adapter(aux->cec.adap); |
| 312 | aux->cec.adap = NULL; |
| 313 | goto unlock; |
| 314 | } |
| 315 | |
| 316 | if (cap & DP_CEC_SNOOPING_CAPABLE) |
| 317 | cec_caps |= CEC_CAP_MONITOR_ALL; |
| 318 | if (cap & DP_CEC_MULTIPLE_LA_CAPABLE) |
| 319 | num_las = CEC_MAX_LOG_ADDRS; |
| 320 | |
| 321 | if (aux->cec.adap) { |
| 322 | if (aux->cec.adap->capabilities == cec_caps && |
| 323 | aux->cec.adap->available_log_addrs == num_las) { |
| 324 | /* Unchanged, so just set the phys addr */ |
| 325 | cec_s_phys_addr_from_edid(aux->cec.adap, edid); |
| 326 | goto unlock; |
| 327 | } |
| 328 | /* |
| 329 | * The capabilities changed, so unregister the old |
| 330 | * adapter first. |
| 331 | */ |
| 332 | cec_unregister_adapter(aux->cec.adap); |
| 333 | } |
| 334 | |
| 335 | /* Create a new adapter */ |
| 336 | aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops, |
| 337 | aux, aux->cec.name, cec_caps, |
Venkata Prahlad Valluru | 2db4fa0 | 2020-06-10 01:26:47 +0530 | [diff] [blame] | 338 | num_las, aux->cec.parent); |
Hans Verkuil | 1d4cf02 | 2018-07-11 15:29:07 +0200 | [diff] [blame] | 339 | if (IS_ERR(aux->cec.adap)) { |
| 340 | aux->cec.adap = NULL; |
| 341 | goto unlock; |
| 342 | } |
Venkata Prahlad Valluru | 2db4fa0 | 2020-06-10 01:26:47 +0530 | [diff] [blame] | 343 | if (cec_register_adapter(aux->cec.adap)) { |
Hans Verkuil | 1d4cf02 | 2018-07-11 15:29:07 +0200 | [diff] [blame] | 344 | cec_delete_adapter(aux->cec.adap); |
| 345 | aux->cec.adap = NULL; |
| 346 | } else { |
| 347 | /* |
| 348 | * Update the phys addr for the new CEC adapter. When called |
| 349 | * from drm_dp_cec_register_connector() edid == NULL, so in |
| 350 | * that case the phys addr is just invalidated. |
| 351 | */ |
| 352 | cec_s_phys_addr_from_edid(aux->cec.adap, edid); |
| 353 | } |
| 354 | unlock: |
| 355 | mutex_unlock(&aux->cec.lock); |
| 356 | } |
| 357 | EXPORT_SYMBOL(drm_dp_cec_set_edid); |
| 358 | |
| 359 | /* |
| 360 | * The EDID disappeared (likely because of the HPD going down). |
| 361 | */ |
| 362 | void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) |
| 363 | { |
| 364 | cancel_delayed_work_sync(&aux->cec.unregister_work); |
| 365 | |
| 366 | mutex_lock(&aux->cec.lock); |
| 367 | if (!aux->cec.adap) |
| 368 | goto unlock; |
| 369 | |
| 370 | cec_phys_addr_invalidate(aux->cec.adap); |
| 371 | /* |
| 372 | * We're done if we want to keep the CEC device |
| 373 | * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the |
| 374 | * DPCD still indicates the CEC capability (expected for an integrated |
| 375 | * HDMI branch device). |
| 376 | */ |
| 377 | if (drm_dp_cec_unregister_delay < NEVER_UNREG_DELAY && |
| 378 | !drm_dp_cec_cap(aux, NULL)) { |
| 379 | /* |
| 380 | * Unregister the CEC adapter after drm_dp_cec_unregister_delay |
| 381 | * seconds. This to debounce short HPD off-and-on cycles from |
| 382 | * displays. |
| 383 | */ |
| 384 | schedule_delayed_work(&aux->cec.unregister_work, |
| 385 | drm_dp_cec_unregister_delay * HZ); |
| 386 | } |
| 387 | unlock: |
| 388 | mutex_unlock(&aux->cec.lock); |
| 389 | } |
| 390 | EXPORT_SYMBOL(drm_dp_cec_unset_edid); |
| 391 | |
| 392 | /** |
| 393 | * drm_dp_cec_register_connector() - register a new connector |
| 394 | * @aux: DisplayPort AUX channel |
| 395 | * @name: name of the CEC device |
| 396 | * @parent: parent device |
| 397 | * |
| 398 | * A new connector was registered with associated CEC adapter name and |
| 399 | * CEC adapter parent device. After registering the name and parent |
| 400 | * drm_dp_cec_set_edid() is called to check if the connector supports |
| 401 | * CEC and to register a CEC adapter if that is the case. |
| 402 | */ |
| 403 | void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, |
| 404 | struct device *parent) |
| 405 | { |
Venkata Prahlad Valluru | 2db4fa0 | 2020-06-10 01:26:47 +0530 | [diff] [blame] | 406 | if (aux->cec.adap) { |
| 407 | WARN_ON(aux->cec.adap); |
| 408 | return; |
| 409 | } |
Hans Verkuil | 1d4cf02 | 2018-07-11 15:29:07 +0200 | [diff] [blame] | 410 | aux->cec.name = name; |
| 411 | aux->cec.parent = parent; |
| 412 | INIT_DELAYED_WORK(&aux->cec.unregister_work, |
| 413 | drm_dp_cec_unregister_work); |
| 414 | |
| 415 | drm_dp_cec_set_edid(aux, NULL); |
| 416 | } |
| 417 | EXPORT_SYMBOL(drm_dp_cec_register_connector); |
| 418 | |
| 419 | /** |
| 420 | * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any |
| 421 | * @aux: DisplayPort AUX channel |
| 422 | */ |
| 423 | void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) |
| 424 | { |
| 425 | if (!aux->cec.adap) |
| 426 | return; |
| 427 | cancel_delayed_work_sync(&aux->cec.unregister_work); |
| 428 | cec_unregister_adapter(aux->cec.adap); |
| 429 | aux->cec.adap = NULL; |
| 430 | } |
| 431 | EXPORT_SYMBOL(drm_dp_cec_unregister_connector); |