1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * Copyright (C) 2012 by Alan Stern 4 */ 5 6/* This file is part of ehci-hcd.c */ 7 8/*-------------------------------------------------------------------------*/ 9 10/* Set a bit in the USBCMD register */ 11static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit) 12{ 13 ehci->command |= bit; 14 ehci_writel(ehci, ehci->command, &ehci->regs->command); 15 16 /* unblock posted write */ 17 ehci_readl(ehci, &ehci->regs->command); 18} 19 20/* Clear a bit in the USBCMD register */ 21static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit) 22{ 23 ehci->command &= ~bit; 24 ehci_writel(ehci, ehci->command, &ehci->regs->command); 25 26 /* unblock posted write */ 27 ehci_readl(ehci, &ehci->regs->command); 28} 29 30/*-------------------------------------------------------------------------*/ 31 32/* 33 * EHCI timer support... Now using hrtimers. 34 * 35 * Lots of different events are triggered from ehci->hrtimer. Whenever 36 * the timer routine runs, it checks each possible event; events that are 37 * currently enabled and whose expiration time has passed get handled. 38 * The set of enabled events is stored as a collection of bitflags in 39 * ehci->enabled_hrtimer_events, and they are numbered in order of 40 * increasing delay values (ranging between 1 ms and 100 ms). 41 * 42 * Rather than implementing a sorted list or tree of all pending events, 43 * we keep track only of the lowest-numbered pending event, in 44 * ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its 45 * expiration time is set to the timeout value for this event. 46 * 47 * As a result, events might not get handled right away; the actual delay 48 * could be anywhere up to twice the requested delay. This doesn't 49 * matter, because none of the events are especially time-critical. The 50 * ones that matter most all have a delay of 1 ms, so they will be 51 * handled after 2 ms at most, which is okay. In addition to this, we 52 * allow for an expiration range of 1 ms. 53 */ 54 55/* 56 * Delay lengths for the hrtimer event types. 57 * Keep this list sorted by delay length, in the same order as 58 * the event types indexed by enum ehci_hrtimer_event in ehci.h. 59 */ 60static unsigned event_delays_ns[] = { 61 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_ASS */ 62 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */ 63 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_DEAD */ 64 1125 * NSEC_PER_USEC, /* EHCI_HRTIMER_UNLINK_INTR */ 65 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_FREE_ITDS */ 66 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ACTIVE_UNLINK */ 67 5 * NSEC_PER_MSEC, /* EHCI_HRTIMER_START_UNLINK_INTR */ 68 6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 69 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */ 70 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 71 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */ 72 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */ 73}; 74 75/* Enable a pending hrtimer event */ 76static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event, 77 bool resched) 78{ 79 ktime_t *timeout = &ehci->hr_timeouts[event]; 80 81 if (resched) 82 *timeout = ktime_add(ktime_get(), event_delays_ns[event]); 83 ehci->enabled_hrtimer_events |= (1 << event); 84 85 /* Track only the lowest-numbered pending event */ 86 if (event < ehci->next_hrtimer_event) { 87 ehci->next_hrtimer_event = event; 88 hrtimer_start_range_ns(&ehci->hrtimer, *timeout, 89 NSEC_PER_MSEC, HRTIMER_MODE_ABS); 90 } 91} 92 93 94/* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */ 95static void ehci_poll_ASS(struct ehci_hcd *ehci) 96{ 97 unsigned actual, want; 98 99 /* Don't enable anything if the controller isn't running (e.g., died) */ 100 if (ehci->rh_state != EHCI_RH_RUNNING) 101 return; 102 103 want = (ehci->command & CMD_ASE) ? STS_ASS : 0; 104 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS; 105 106 if (want != actual) { 107 108 /* Poll again later, but give up after about 2-4 ms */ 109 if (ehci->ASS_poll_count++ < 2) { 110 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true); 111 return; 112 } 113 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n", 114 want, actual); 115 } 116 ehci->ASS_poll_count = 0; 117 118 /* The status is up-to-date; restart or stop the schedule as needed */ 119 if (want == 0) { /* Stopped */ 120 if (ehci->async_count > 0) 121 ehci_set_command_bit(ehci, CMD_ASE); 122 123 } else { /* Running */ 124 if (ehci->async_count == 0) { 125 126 /* Turn off the schedule after a while */ 127 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC, 128 true); 129 } 130 } 131} 132 133/* Turn off the async schedule after a brief delay */ 134static void ehci_disable_ASE(struct ehci_hcd *ehci) 135{ 136 ehci_clear_command_bit(ehci, CMD_ASE); 137} 138 139 140/* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */ 141static void ehci_poll_PSS(struct ehci_hcd *ehci) 142{ 143 unsigned actual, want; 144 145 /* Don't do anything if the controller isn't running (e.g., died) */ 146 if (ehci->rh_state != EHCI_RH_RUNNING) 147 return; 148 149 want = (ehci->command & CMD_PSE) ? STS_PSS : 0; 150 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS; 151 152 if (want != actual) { 153 154 /* Poll again later, but give up after about 2-4 ms */ 155 if (ehci->PSS_poll_count++ < 2) { 156 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true); 157 return; 158 } 159 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n", 160 want, actual); 161 } 162 ehci->PSS_poll_count = 0; 163 164 /* The status is up-to-date; restart or stop the schedule as needed */ 165 if (want == 0) { /* Stopped */ 166 if (ehci->periodic_count > 0) 167 ehci_set_command_bit(ehci, CMD_PSE); 168 169 } else { /* Running */ 170 if (ehci->periodic_count == 0) { 171 172 /* Turn off the schedule after a while */ 173 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC, 174 true); 175 } 176 } 177} 178 179/* Turn off the periodic schedule after a brief delay */ 180static void ehci_disable_PSE(struct ehci_hcd *ehci) 181{ 182 ehci_clear_command_bit(ehci, CMD_PSE); 183} 184 185 186/* Poll the STS_HALT status bit; see when a dead controller stops */ 187static void ehci_handle_controller_death(struct ehci_hcd *ehci) 188{ 189 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) { 190 191 /* Give up after a few milliseconds */ 192 if (ehci->died_poll_count++ < 5) { 193 /* Try again later */ 194 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true); 195 return; 196 } 197 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n"); 198 } 199 200 /* Clean up the mess */ 201 ehci->rh_state = EHCI_RH_HALTED; 202 ehci_writel(ehci, 0, &ehci->regs->configured_flag); 203 ehci_writel(ehci, 0, &ehci->regs->intr_enable); 204 ehci_work(ehci); 205 end_unlink_async(ehci); 206 207 /* Not in process context, so don't try to reset the controller */ 208} 209 210/* start to unlink interrupt QHs */ 211static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci) 212{ 213 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 214 215 /* 216 * Process all the QHs on the intr_unlink list that were added 217 * before the current unlink cycle began. The list is in 218 * temporal order, so stop when we reach the first entry in the 219 * current cycle. But if the root hub isn't running then 220 * process all the QHs on the list. 221 */ 222 while (!list_empty(&ehci->intr_unlink_wait)) { 223 struct ehci_qh *qh; 224 225 qh = list_first_entry(&ehci->intr_unlink_wait, 226 struct ehci_qh, unlink_node); 227 if (!stopped && (qh->unlink_cycle == 228 ehci->intr_unlink_wait_cycle)) 229 break; 230 list_del_init(&qh->unlink_node); 231 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY; 232 start_unlink_intr(ehci, qh); 233 } 234 235 /* Handle remaining entries later */ 236 if (!list_empty(&ehci->intr_unlink_wait)) { 237 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true); 238 ++ehci->intr_unlink_wait_cycle; 239 } 240} 241 242/* Handle unlinked interrupt QHs once they are gone from the hardware */ 243static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci) 244{ 245 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING); 246 247 /* 248 * Process all the QHs on the intr_unlink list that were added 249 * before the current unlink cycle began. The list is in 250 * temporal order, so stop when we reach the first entry in the 251 * current cycle. But if the root hub isn't running then 252 * process all the QHs on the list. 253 */ 254 ehci->intr_unlinking = true; 255 while (!list_empty(&ehci->intr_unlink)) { 256 struct ehci_qh *qh; 257 258 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh, 259 unlink_node); 260 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle) 261 break; 262 list_del_init(&qh->unlink_node); 263 end_unlink_intr(ehci, qh); 264 } 265 266 /* Handle remaining entries later */ 267 if (!list_empty(&ehci->intr_unlink)) { 268 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true); 269 ++ehci->intr_unlink_cycle; 270 } 271 ehci->intr_unlinking = false; 272} 273 274 275/* Start another free-iTDs/siTDs cycle */ 276static void start_free_itds(struct ehci_hcd *ehci) 277{ 278 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) { 279 ehci->last_itd_to_free = list_entry( 280 ehci->cached_itd_list.prev, 281 struct ehci_itd, itd_list); 282 ehci->last_sitd_to_free = list_entry( 283 ehci->cached_sitd_list.prev, 284 struct ehci_sitd, sitd_list); 285 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true); 286 } 287} 288 289/* Wait for controller to stop using old iTDs and siTDs */ 290static void end_free_itds(struct ehci_hcd *ehci) 291{ 292 struct ehci_itd *itd, *n; 293 struct ehci_sitd *sitd, *sn; 294 295 if (ehci->rh_state < EHCI_RH_RUNNING) { 296 ehci->last_itd_to_free = NULL; 297 ehci->last_sitd_to_free = NULL; 298 } 299 300 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) { 301 list_del(&itd->itd_list); 302 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma); 303 if (itd == ehci->last_itd_to_free) 304 break; 305 } 306 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) { 307 list_del(&sitd->sitd_list); 308 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma); 309 if (sitd == ehci->last_sitd_to_free) 310 break; 311 } 312 313 if (!list_empty(&ehci->cached_itd_list) || 314 !list_empty(&ehci->cached_sitd_list)) 315 start_free_itds(ehci); 316} 317 318 319/* Handle lost (or very late) IAA interrupts */ 320static void ehci_iaa_watchdog(struct ehci_hcd *ehci) 321{ 322 u32 cmd, status; 323 324 /* 325 * Lost IAA irqs wedge things badly; seen first with a vt8235. 326 * So we need this watchdog, but must protect it against both 327 * (a) SMP races against real IAA firing and retriggering, and 328 * (b) clean HC shutdown, when IAA watchdog was pending. 329 */ 330 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING) 331 return; 332 333 /* If we get here, IAA is *REALLY* late. It's barely 334 * conceivable that the system is so busy that CMD_IAAD 335 * is still legitimately set, so let's be sure it's 336 * clear before we read STS_IAA. (The HC should clear 337 * CMD_IAAD when it sets STS_IAA.) 338 */ 339 cmd = ehci_readl(ehci, &ehci->regs->command); 340 341 /* 342 * If IAA is set here it either legitimately triggered 343 * after the watchdog timer expired (_way_ late, so we'll 344 * still count it as lost) ... or a silicon erratum: 345 * - VIA seems to set IAA without triggering the IRQ; 346 * - IAAD potentially cleared without setting IAA. 347 */ 348 status = ehci_readl(ehci, &ehci->regs->status); 349 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) { 350 INCR(ehci->stats.lost_iaa); 351 ehci_writel(ehci, STS_IAA, &ehci->regs->status); 352 } 353 354 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd); 355 end_iaa_cycle(ehci); 356} 357 358 359/* Enable the I/O watchdog, if appropriate */ 360static void turn_on_io_watchdog(struct ehci_hcd *ehci) 361{ 362 /* Not needed if the controller isn't running or it's already enabled */ 363 if (ehci->rh_state != EHCI_RH_RUNNING || 364 (ehci->enabled_hrtimer_events & 365 BIT(EHCI_HRTIMER_IO_WATCHDOG))) 366 return; 367 368 /* 369 * Isochronous transfers always need the watchdog. 370 * For other sorts we use it only if the flag is set. 371 */ 372 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog && 373 ehci->async_count + ehci->intr_count > 0)) 374 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true); 375} 376 377 378/* 379 * Handler functions for the hrtimer event types. 380 * Keep this array in the same order as the event types indexed by 381 * enum ehci_hrtimer_event in ehci.h. 382 */ 383static void (*event_handlers[])(struct ehci_hcd *) = { 384 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */ 385 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */ 386 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */ 387 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */ 388 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */ 389 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */ 390 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */ 391 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 392 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */ 393 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 394 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */ 395 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */ 396}; 397 398static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t) 399{ 400 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer); 401 ktime_t now; 402 unsigned long events; 403 unsigned long flags; 404 unsigned e; 405 406 spin_lock_irqsave(&ehci->lock, flags); 407 408 events = ehci->enabled_hrtimer_events; 409 ehci->enabled_hrtimer_events = 0; 410 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT; 411 412 /* 413 * Check each pending event. If its time has expired, handle 414 * the event; otherwise re-enable it. 415 */ 416 now = ktime_get(); 417 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) { 418 if (ktime_compare(now, ehci->hr_timeouts[e]) >= 0) 419 event_handlers[e](ehci); 420 else 421 ehci_enable_event(ehci, e, false); 422 } 423 424 spin_unlock_irqrestore(&ehci->lock, flags); 425 return HRTIMER_NORESTART; 426} 427