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(), event_delays_ns[event]); 92 ehci->enabled_hrtimer_events |= (1 << event); 93 94 /* Track only the lowest-numbered pending event */ 95 if (event < ehci->next_hrtimer_event) { 96 ehci->next_hrtimer_event = event; 97 hrtimer_start_range_ns(&ehci->hrtimer, *timeout, 98 NSEC_PER_MSEC, HRTIMER_MODE_ABS); 99 } 100 } 101 102 103 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */ 104 static void ehci_poll_ASS(struct ehci_hcd *ehci) 105 { 106 unsigned actual, want; 107 108 /* Don't enable anything if the controller isn't running (e.g., died) */ 109 if (ehci->rh_state != EHCI_RH_RUNNING) 110 return; 111 112 want = (ehci->command & CMD_ASE) ? STS_ASS : 0; 113 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS; 114 115 if (want != actual) { 116 117 /* Poll again later, but give up after about 2-4 ms */ 118 if (ehci->ASS_poll_count++ < 2) { 119 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true); 120 return; 121 } 122 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n", 123 want, actual); 124 } 125 ehci->ASS_poll_count = 0; 126 127 /* The status is up-to-date; restart or stop the schedule as needed */ 128 if (want == 0) { /* Stopped */ 129 if (ehci->async_count > 0) 130 ehci_set_command_bit(ehci, CMD_ASE); 131 132 } else { /* Running */ 133 if (ehci->async_count == 0) { 134 135 /* Turn off the schedule after a while */ 136 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC, 137 true); 138 } 139 } 140 } 141 142 /* Turn off the async schedule after a brief delay */ 143 static void ehci_disable_ASE(struct ehci_hcd *ehci) 144 { 145 ehci_clear_command_bit(ehci, CMD_ASE); 146 } 147 148 149 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */ 150 static void ehci_poll_PSS(struct ehci_hcd *ehci) 151 { 152 unsigned actual, want; 153 154 /* Don't do anything if the controller isn't running (e.g., died) */ 155 if (ehci->rh_state != EHCI_RH_RUNNING) 156 return; 157 158 want = (ehci->command & CMD_PSE) ? STS_PSS : 0; 159 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS; 160 161 if (want != actual) { 162 163 /* Poll again later, but give up after about 2-4 ms */ 164 if (ehci->PSS_poll_count++ < 2) { 165 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true); 166 return; 167 } 168 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n", 169 want, actual); 170 } 171 ehci->PSS_poll_count = 0; 172 173 /* The status is up-to-date; restart or stop the schedule as needed */ 174 if (want == 0) { /* Stopped */ 175 if (ehci->periodic_count > 0) 176 ehci_set_command_bit(ehci, CMD_PSE); 177 178 } else { /* Running */ 179 if (ehci->periodic_count == 0) { 180 181 /* Turn off the schedule after a while */ 182 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC, 183 true); 184 } 185 } 186 } 187 188 /* Turn off the periodic schedule after a brief delay */ 189 static void ehci_disable_PSE(struct ehci_hcd *ehci) 190 { 191 ehci_clear_command_bit(ehci, CMD_PSE); 192 } 193 194 195 /* Poll the STS_HALT status bit; see when a dead controller stops */ 196 static void ehci_handle_controller_death(struct ehci_hcd *ehci) 197 { 198 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) { 199 200 /* Give up after a few milliseconds */ 201 if (ehci->died_poll_count++ < 5) { 202 /* Try again later */ 203 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true); 204 return; 205 } 206 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n"); 207 } 208 209 /* Clean up the mess */ 210 ehci->rh_state = EHCI_RH_HALTED; 211 ehci_writel(ehci, 0, &ehci->regs->configured_flag); 212 ehci_writel(ehci, 0, &ehci->regs->intr_enable); 213 ehci_work(ehci); 214 end_unlink_async(ehci); 215 216 /* Not in process context, so don't try to reset the controller */ 217 } 218 219 /* start to unlink interrupt QHs */ 220 static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci) 221 { 222 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 223 224 /* 225 * Process all the QHs on the intr_unlink list that were added 226 * before the current unlink cycle began. The list is in 227 * temporal order, so stop when we reach the first entry in the 228 * current cycle. But if the root hub isn't running then 229 * process all the QHs on the list. 230 */ 231 while (!list_empty(&ehci->intr_unlink_wait)) { 232 struct ehci_qh *qh; 233 234 qh = list_first_entry(&ehci->intr_unlink_wait, 235 struct ehci_qh, unlink_node); 236 if (!stopped && (qh->unlink_cycle == 237 ehci->intr_unlink_wait_cycle)) 238 break; 239 list_del_init(&qh->unlink_node); 240 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY; 241 start_unlink_intr(ehci, qh); 242 } 243 244 /* Handle remaining entries later */ 245 if (!list_empty(&ehci->intr_unlink_wait)) { 246 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true); 247 ++ehci->intr_unlink_wait_cycle; 248 } 249 } 250 251 /* Handle unlinked interrupt QHs once they are gone from the hardware */ 252 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci) 253 { 254 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 255 256 /* 257 * Process all the QHs on the intr_unlink list that were added 258 * before the current unlink cycle began. The list is in 259 * temporal order, so stop when we reach the first entry in the 260 * current cycle. But if the root hub isn't running then 261 * process all the QHs on the list. 262 */ 263 ehci->intr_unlinking = true; 264 while (!list_empty(&ehci->intr_unlink)) { 265 struct ehci_qh *qh; 266 267 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh, 268 unlink_node); 269 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle) 270 break; 271 list_del_init(&qh->unlink_node); 272 end_unlink_intr(ehci, qh); 273 } 274 275 /* Handle remaining entries later */ 276 if (!list_empty(&ehci->intr_unlink)) { 277 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true); 278 ++ehci->intr_unlink_cycle; 279 } 280 ehci->intr_unlinking = false; 281 } 282 283 284 /* Start another free-iTDs/siTDs cycle */ 285 static void start_free_itds(struct ehci_hcd *ehci) 286 { 287 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) { 288 ehci->last_itd_to_free = list_entry( 289 ehci->cached_itd_list.prev, 290 struct ehci_itd, itd_list); 291 ehci->last_sitd_to_free = list_entry( 292 ehci->cached_sitd_list.prev, 293 struct ehci_sitd, sitd_list); 294 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true); 295 } 296 } 297 298 /* Wait for controller to stop using old iTDs and siTDs */ 299 static void end_free_itds(struct ehci_hcd *ehci) 300 { 301 struct ehci_itd *itd, *n; 302 struct ehci_sitd *sitd, *sn; 303 304 if (ehci->rh_state < EHCI_RH_RUNNING) { 305 ehci->last_itd_to_free = NULL; 306 ehci->last_sitd_to_free = NULL; 307 } 308 309 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) { 310 list_del(&itd->itd_list); 311 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma); 312 if (itd == ehci->last_itd_to_free) 313 break; 314 } 315 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) { 316 list_del(&sitd->sitd_list); 317 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma); 318 if (sitd == ehci->last_sitd_to_free) 319 break; 320 } 321 322 if (!list_empty(&ehci->cached_itd_list) || 323 !list_empty(&ehci->cached_sitd_list)) 324 start_free_itds(ehci); 325 } 326 327 328 /* Handle lost (or very late) IAA interrupts */ 329 static void ehci_iaa_watchdog(struct ehci_hcd *ehci) 330 { 331 u32 cmd, status; 332 333 /* 334 * Lost IAA irqs wedge things badly; seen first with a vt8235. 335 * So we need this watchdog, but must protect it against both 336 * (a) SMP races against real IAA firing and retriggering, and 337 * (b) clean HC shutdown, when IAA watchdog was pending. 338 */ 339 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING) 340 return; 341 342 /* If we get here, IAA is *REALLY* late. It's barely 343 * conceivable that the system is so busy that CMD_IAAD 344 * is still legitimately set, so let's be sure it's 345 * clear before we read STS_IAA. (The HC should clear 346 * CMD_IAAD when it sets STS_IAA.) 347 */ 348 cmd = ehci_readl(ehci, &ehci->regs->command); 349 350 /* 351 * If IAA is set here it either legitimately triggered 352 * after the watchdog timer expired (_way_ late, so we'll 353 * still count it as lost) ... or a silicon erratum: 354 * - VIA seems to set IAA without triggering the IRQ; 355 * - IAAD potentially cleared without setting IAA. 356 */ 357 status = ehci_readl(ehci, &ehci->regs->status); 358 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) { 359 COUNT(ehci->stats.lost_iaa); 360 ehci_writel(ehci, STS_IAA, &ehci->regs->status); 361 } 362 363 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd); 364 end_iaa_cycle(ehci); 365 } 366 367 368 /* Enable the I/O watchdog, if appropriate */ 369 static void turn_on_io_watchdog(struct ehci_hcd *ehci) 370 { 371 /* Not needed if the controller isn't running or it's already enabled */ 372 if (ehci->rh_state != EHCI_RH_RUNNING || 373 (ehci->enabled_hrtimer_events & 374 BIT(EHCI_HRTIMER_IO_WATCHDOG))) 375 return; 376 377 /* 378 * Isochronous transfers always need the watchdog. 379 * For other sorts we use it only if the flag is set. 380 */ 381 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog && 382 ehci->async_count + ehci->intr_count > 0)) 383 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true); 384 } 385 386 387 /* 388 * Handler functions for the hrtimer event types. 389 * Keep this array in the same order as the event types indexed by 390 * enum ehci_hrtimer_event in ehci.h. 391 */ 392 static void (*event_handlers[])(struct ehci_hcd *) = { 393 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */ 394 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */ 395 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */ 396 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */ 397 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */ 398 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */ 399 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */ 400 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 401 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */ 402 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 403 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */ 404 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */ 405 }; 406 407 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t) 408 { 409 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer); 410 ktime_t now; 411 unsigned long events; 412 unsigned long flags; 413 unsigned e; 414 415 spin_lock_irqsave(&ehci->lock, flags); 416 417 events = ehci->enabled_hrtimer_events; 418 ehci->enabled_hrtimer_events = 0; 419 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT; 420 421 /* 422 * Check each pending event. If its time has expired, handle 423 * the event; otherwise re-enable it. 424 */ 425 now = ktime_get(); 426 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) { 427 if (now >= ehci->hr_timeouts[e]) 428 event_handlers[e](ehci); 429 else 430 ehci_enable_event(ehci, e, false); 431 } 432 433 spin_unlock_irqrestore(&ehci->lock, flags); 434 return HRTIMER_NORESTART; 435 } 436