1 /* 2 * Copyright (C) 2012 by Alan Stern 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License as published by the 6 * Free Software Foundation; either version 2 of the License, or (at your 7 * option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 11 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * for more details. 13 */ 14 15 /* This file is part of ehci-hcd.c */ 16 17 /*-------------------------------------------------------------------------*/ 18 19 /* Set a bit in the USBCMD register */ 20 static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit) 21 { 22 ehci->command |= bit; 23 ehci_writel(ehci, ehci->command, &ehci->regs->command); 24 25 /* unblock posted write */ 26 ehci_readl(ehci, &ehci->regs->command); 27 } 28 29 /* Clear a bit in the USBCMD register */ 30 static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit) 31 { 32 ehci->command &= ~bit; 33 ehci_writel(ehci, ehci->command, &ehci->regs->command); 34 35 /* unblock posted write */ 36 ehci_readl(ehci, &ehci->regs->command); 37 } 38 39 /*-------------------------------------------------------------------------*/ 40 41 /* 42 * EHCI timer support... Now using hrtimers. 43 * 44 * Lots of different events are triggered from ehci->hrtimer. Whenever 45 * the timer routine runs, it checks each possible event; events that are 46 * currently enabled and whose expiration time has passed get handled. 47 * The set of enabled events is stored as a collection of bitflags in 48 * ehci->enabled_hrtimer_events, and they are numbered in order of 49 * increasing delay values (ranging between 1 ms and 100 ms). 50 * 51 * Rather than implementing a sorted list or tree of all pending events, 52 * we keep track only of the lowest-numbered pending event, in 53 * ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its 54 * expiration time is set to the timeout value for this event. 55 * 56 * As a result, events might not get handled right away; the actual delay 57 * could be anywhere up to twice the requested delay. This doesn't 58 * matter, because none of the events are especially time-critical. The 59 * ones that matter most all have a delay of 1 ms, so they will be 60 * handled after 2 ms at most, which is okay. In addition to this, we 61 * allow for an expiration range of 1 ms. 62 */ 63 64 /* 65 * Delay lengths for the hrtimer event types. 66 * Keep this list sorted by delay length, in the same order as 67 * the event types indexed by enum ehci_hrtimer_event in ehci.h. 68 */ 69 static unsigned event_delays_ns[] = { 70 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_ASS */ 71 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */ 72 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_DEAD */ 73 1125 * NSEC_PER_USEC, /* EHCI_HRTIMER_UNLINK_INTR */ 74 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_FREE_ITDS */ 75 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ACTIVE_UNLINK */ 76 5 * NSEC_PER_MSEC, /* EHCI_HRTIMER_START_UNLINK_INTR */ 77 6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 78 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */ 79 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 80 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */ 81 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */ 82 }; 83 84 /* Enable a pending hrtimer event */ 85 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event, 86 bool resched) 87 { 88 ktime_t *timeout = &ehci->hr_timeouts[event]; 89 90 if (resched) 91 *timeout = ktime_add(ktime_get(), 92 ktime_set(0, event_delays_ns[event])); 93 ehci->enabled_hrtimer_events |= (1 << event); 94 95 /* Track only the lowest-numbered pending event */ 96 if (event < ehci->next_hrtimer_event) { 97 ehci->next_hrtimer_event = event; 98 hrtimer_start_range_ns(&ehci->hrtimer, *timeout, 99 NSEC_PER_MSEC, HRTIMER_MODE_ABS); 100 } 101 } 102 103 104 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */ 105 static void ehci_poll_ASS(struct ehci_hcd *ehci) 106 { 107 unsigned actual, want; 108 109 /* Don't enable anything if the controller isn't running (e.g., died) */ 110 if (ehci->rh_state != EHCI_RH_RUNNING) 111 return; 112 113 want = (ehci->command & CMD_ASE) ? STS_ASS : 0; 114 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS; 115 116 if (want != actual) { 117 118 /* Poll again later, but give up after about 2-4 ms */ 119 if (ehci->ASS_poll_count++ < 2) { 120 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true); 121 return; 122 } 123 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n", 124 want, actual); 125 } 126 ehci->ASS_poll_count = 0; 127 128 /* The status is up-to-date; restart or stop the schedule as needed */ 129 if (want == 0) { /* Stopped */ 130 if (ehci->async_count > 0) 131 ehci_set_command_bit(ehci, CMD_ASE); 132 133 } else { /* Running */ 134 if (ehci->async_count == 0) { 135 136 /* Turn off the schedule after a while */ 137 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC, 138 true); 139 } 140 } 141 } 142 143 /* Turn off the async schedule after a brief delay */ 144 static void ehci_disable_ASE(struct ehci_hcd *ehci) 145 { 146 ehci_clear_command_bit(ehci, CMD_ASE); 147 } 148 149 150 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */ 151 static void ehci_poll_PSS(struct ehci_hcd *ehci) 152 { 153 unsigned actual, want; 154 155 /* Don't do anything if the controller isn't running (e.g., died) */ 156 if (ehci->rh_state != EHCI_RH_RUNNING) 157 return; 158 159 want = (ehci->command & CMD_PSE) ? STS_PSS : 0; 160 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS; 161 162 if (want != actual) { 163 164 /* Poll again later, but give up after about 2-4 ms */ 165 if (ehci->PSS_poll_count++ < 2) { 166 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true); 167 return; 168 } 169 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n", 170 want, actual); 171 } 172 ehci->PSS_poll_count = 0; 173 174 /* The status is up-to-date; restart or stop the schedule as needed */ 175 if (want == 0) { /* Stopped */ 176 if (ehci->periodic_count > 0) 177 ehci_set_command_bit(ehci, CMD_PSE); 178 179 } else { /* Running */ 180 if (ehci->periodic_count == 0) { 181 182 /* Turn off the schedule after a while */ 183 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC, 184 true); 185 } 186 } 187 } 188 189 /* Turn off the periodic schedule after a brief delay */ 190 static void ehci_disable_PSE(struct ehci_hcd *ehci) 191 { 192 ehci_clear_command_bit(ehci, CMD_PSE); 193 } 194 195 196 /* Poll the STS_HALT status bit; see when a dead controller stops */ 197 static void ehci_handle_controller_death(struct ehci_hcd *ehci) 198 { 199 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) { 200 201 /* Give up after a few milliseconds */ 202 if (ehci->died_poll_count++ < 5) { 203 /* Try again later */ 204 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true); 205 return; 206 } 207 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n"); 208 } 209 210 /* Clean up the mess */ 211 ehci->rh_state = EHCI_RH_HALTED; 212 ehci_writel(ehci, 0, &ehci->regs->configured_flag); 213 ehci_writel(ehci, 0, &ehci->regs->intr_enable); 214 ehci_work(ehci); 215 end_unlink_async(ehci); 216 217 /* Not in process context, so don't try to reset the controller */ 218 } 219 220 /* start to unlink interrupt QHs */ 221 static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci) 222 { 223 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 224 225 /* 226 * Process all the QHs on the intr_unlink list that were added 227 * before the current unlink cycle began. The list is in 228 * temporal order, so stop when we reach the first entry in the 229 * current cycle. But if the root hub isn't running then 230 * process all the QHs on the list. 231 */ 232 while (!list_empty(&ehci->intr_unlink_wait)) { 233 struct ehci_qh *qh; 234 235 qh = list_first_entry(&ehci->intr_unlink_wait, 236 struct ehci_qh, unlink_node); 237 if (!stopped && (qh->unlink_cycle == 238 ehci->intr_unlink_wait_cycle)) 239 break; 240 list_del_init(&qh->unlink_node); 241 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY; 242 start_unlink_intr(ehci, qh); 243 } 244 245 /* Handle remaining entries later */ 246 if (!list_empty(&ehci->intr_unlink_wait)) { 247 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true); 248 ++ehci->intr_unlink_wait_cycle; 249 } 250 } 251 252 /* Handle unlinked interrupt QHs once they are gone from the hardware */ 253 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci) 254 { 255 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 256 257 /* 258 * Process all the QHs on the intr_unlink list that were added 259 * before the current unlink cycle began. The list is in 260 * temporal order, so stop when we reach the first entry in the 261 * current cycle. But if the root hub isn't running then 262 * process all the QHs on the list. 263 */ 264 ehci->intr_unlinking = true; 265 while (!list_empty(&ehci->intr_unlink)) { 266 struct ehci_qh *qh; 267 268 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh, 269 unlink_node); 270 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle) 271 break; 272 list_del_init(&qh->unlink_node); 273 end_unlink_intr(ehci, qh); 274 } 275 276 /* Handle remaining entries later */ 277 if (!list_empty(&ehci->intr_unlink)) { 278 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true); 279 ++ehci->intr_unlink_cycle; 280 } 281 ehci->intr_unlinking = false; 282 } 283 284 285 /* Start another free-iTDs/siTDs cycle */ 286 static void start_free_itds(struct ehci_hcd *ehci) 287 { 288 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) { 289 ehci->last_itd_to_free = list_entry( 290 ehci->cached_itd_list.prev, 291 struct ehci_itd, itd_list); 292 ehci->last_sitd_to_free = list_entry( 293 ehci->cached_sitd_list.prev, 294 struct ehci_sitd, sitd_list); 295 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true); 296 } 297 } 298 299 /* Wait for controller to stop using old iTDs and siTDs */ 300 static void end_free_itds(struct ehci_hcd *ehci) 301 { 302 struct ehci_itd *itd, *n; 303 struct ehci_sitd *sitd, *sn; 304 305 if (ehci->rh_state < EHCI_RH_RUNNING) { 306 ehci->last_itd_to_free = NULL; 307 ehci->last_sitd_to_free = NULL; 308 } 309 310 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) { 311 list_del(&itd->itd_list); 312 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma); 313 if (itd == ehci->last_itd_to_free) 314 break; 315 } 316 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) { 317 list_del(&sitd->sitd_list); 318 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma); 319 if (sitd == ehci->last_sitd_to_free) 320 break; 321 } 322 323 if (!list_empty(&ehci->cached_itd_list) || 324 !list_empty(&ehci->cached_sitd_list)) 325 start_free_itds(ehci); 326 } 327 328 329 /* Handle lost (or very late) IAA interrupts */ 330 static void ehci_iaa_watchdog(struct ehci_hcd *ehci) 331 { 332 u32 cmd, status; 333 334 /* 335 * Lost IAA irqs wedge things badly; seen first with a vt8235. 336 * So we need this watchdog, but must protect it against both 337 * (a) SMP races against real IAA firing and retriggering, and 338 * (b) clean HC shutdown, when IAA watchdog was pending. 339 */ 340 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING) 341 return; 342 343 /* If we get here, IAA is *REALLY* late. It's barely 344 * conceivable that the system is so busy that CMD_IAAD 345 * is still legitimately set, so let's be sure it's 346 * clear before we read STS_IAA. (The HC should clear 347 * CMD_IAAD when it sets STS_IAA.) 348 */ 349 cmd = ehci_readl(ehci, &ehci->regs->command); 350 351 /* 352 * If IAA is set here it either legitimately triggered 353 * after the watchdog timer expired (_way_ late, so we'll 354 * still count it as lost) ... or a silicon erratum: 355 * - VIA seems to set IAA without triggering the IRQ; 356 * - IAAD potentially cleared without setting IAA. 357 */ 358 status = ehci_readl(ehci, &ehci->regs->status); 359 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) { 360 COUNT(ehci->stats.lost_iaa); 361 ehci_writel(ehci, STS_IAA, &ehci->regs->status); 362 } 363 364 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd); 365 end_iaa_cycle(ehci); 366 } 367 368 369 /* Enable the I/O watchdog, if appropriate */ 370 static void turn_on_io_watchdog(struct ehci_hcd *ehci) 371 { 372 /* Not needed if the controller isn't running or it's already enabled */ 373 if (ehci->rh_state != EHCI_RH_RUNNING || 374 (ehci->enabled_hrtimer_events & 375 BIT(EHCI_HRTIMER_IO_WATCHDOG))) 376 return; 377 378 /* 379 * Isochronous transfers always need the watchdog. 380 * For other sorts we use it only if the flag is set. 381 */ 382 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog && 383 ehci->async_count + ehci->intr_count > 0)) 384 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true); 385 } 386 387 388 /* 389 * Handler functions for the hrtimer event types. 390 * Keep this array in the same order as the event types indexed by 391 * enum ehci_hrtimer_event in ehci.h. 392 */ 393 static void (*event_handlers[])(struct ehci_hcd *) = { 394 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */ 395 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */ 396 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */ 397 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */ 398 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */ 399 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */ 400 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */ 401 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 402 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */ 403 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 404 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */ 405 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */ 406 }; 407 408 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t) 409 { 410 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer); 411 ktime_t now; 412 unsigned long events; 413 unsigned long flags; 414 unsigned e; 415 416 spin_lock_irqsave(&ehci->lock, flags); 417 418 events = ehci->enabled_hrtimer_events; 419 ehci->enabled_hrtimer_events = 0; 420 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT; 421 422 /* 423 * Check each pending event. If its time has expired, handle 424 * the event; otherwise re-enable it. 425 */ 426 now = ktime_get(); 427 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) { 428 if (now.tv64 >= ehci->hr_timeouts[e].tv64) 429 event_handlers[e](ehci); 430 else 431 ehci_enable_event(ehci, e, false); 432 } 433 434 spin_unlock_irqrestore(&ehci->lock, flags); 435 return HRTIMER_NORESTART; 436 } 437