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 6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 76 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */ 77 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 78 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */ 79 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */ 80 }; 81 82 /* Enable a pending hrtimer event */ 83 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event, 84 bool resched) 85 { 86 ktime_t *timeout = &ehci->hr_timeouts[event]; 87 88 if (resched) 89 *timeout = ktime_add(ktime_get(), 90 ktime_set(0, event_delays_ns[event])); 91 ehci->enabled_hrtimer_events |= (1 << event); 92 93 /* Track only the lowest-numbered pending event */ 94 if (event < ehci->next_hrtimer_event) { 95 ehci->next_hrtimer_event = event; 96 hrtimer_start_range_ns(&ehci->hrtimer, *timeout, 97 NSEC_PER_MSEC, HRTIMER_MODE_ABS); 98 } 99 } 100 101 102 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */ 103 static void ehci_poll_ASS(struct ehci_hcd *ehci) 104 { 105 unsigned actual, want; 106 107 /* Don't enable anything if the controller isn't running (e.g., died) */ 108 if (ehci->rh_state != EHCI_RH_RUNNING) 109 return; 110 111 want = (ehci->command & CMD_ASE) ? STS_ASS : 0; 112 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS; 113 114 if (want != actual) { 115 116 /* Poll again later, but give up after about 20 ms */ 117 if (ehci->ASS_poll_count++ < 20) { 118 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true); 119 return; 120 } 121 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n", 122 want, actual); 123 } 124 ehci->ASS_poll_count = 0; 125 126 /* The status is up-to-date; restart or stop the schedule as needed */ 127 if (want == 0) { /* Stopped */ 128 if (ehci->async_count > 0) 129 ehci_set_command_bit(ehci, CMD_ASE); 130 131 } else { /* Running */ 132 if (ehci->async_count == 0) { 133 134 /* Turn off the schedule after a while */ 135 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC, 136 true); 137 } 138 } 139 } 140 141 /* Turn off the async schedule after a brief delay */ 142 static void ehci_disable_ASE(struct ehci_hcd *ehci) 143 { 144 ehci_clear_command_bit(ehci, CMD_ASE); 145 } 146 147 148 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */ 149 static void ehci_poll_PSS(struct ehci_hcd *ehci) 150 { 151 unsigned actual, want; 152 153 /* Don't do anything if the controller isn't running (e.g., died) */ 154 if (ehci->rh_state != EHCI_RH_RUNNING) 155 return; 156 157 want = (ehci->command & CMD_PSE) ? STS_PSS : 0; 158 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS; 159 160 if (want != actual) { 161 162 /* Poll again later, but give up after about 20 ms */ 163 if (ehci->PSS_poll_count++ < 20) { 164 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true); 165 return; 166 } 167 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n", 168 want, actual); 169 } 170 ehci->PSS_poll_count = 0; 171 172 /* The status is up-to-date; restart or stop the schedule as needed */ 173 if (want == 0) { /* Stopped */ 174 if (ehci->periodic_count > 0) 175 ehci_set_command_bit(ehci, CMD_PSE); 176 177 } else { /* Running */ 178 if (ehci->periodic_count == 0) { 179 180 /* Turn off the schedule after a while */ 181 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC, 182 true); 183 } 184 } 185 } 186 187 /* Turn off the periodic schedule after a brief delay */ 188 static void ehci_disable_PSE(struct ehci_hcd *ehci) 189 { 190 ehci_clear_command_bit(ehci, CMD_PSE); 191 } 192 193 194 /* Poll the STS_HALT status bit; see when a dead controller stops */ 195 static void ehci_handle_controller_death(struct ehci_hcd *ehci) 196 { 197 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) { 198 199 /* Give up after a few milliseconds */ 200 if (ehci->died_poll_count++ < 5) { 201 /* Try again later */ 202 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true); 203 return; 204 } 205 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n"); 206 } 207 208 /* Clean up the mess */ 209 ehci->rh_state = EHCI_RH_HALTED; 210 ehci_writel(ehci, 0, &ehci->regs->configured_flag); 211 ehci_writel(ehci, 0, &ehci->regs->intr_enable); 212 ehci_work(ehci); 213 end_unlink_async(ehci); 214 215 /* Not in process context, so don't try to reset the controller */ 216 } 217 218 219 /* Handle unlinked interrupt QHs once they are gone from the hardware */ 220 static void ehci_handle_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 ehci->intr_unlinking = true; 232 while (ehci->intr_unlink) { 233 struct ehci_qh *qh = ehci->intr_unlink; 234 235 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle) 236 break; 237 ehci->intr_unlink = qh->unlink_next; 238 qh->unlink_next = NULL; 239 end_unlink_intr(ehci, qh); 240 } 241 242 /* Handle remaining entries later */ 243 if (ehci->intr_unlink) { 244 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true); 245 ++ehci->intr_unlink_cycle; 246 } 247 ehci->intr_unlinking = false; 248 } 249 250 251 /* Start another free-iTDs/siTDs cycle */ 252 static void start_free_itds(struct ehci_hcd *ehci) 253 { 254 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) { 255 ehci->last_itd_to_free = list_entry( 256 ehci->cached_itd_list.prev, 257 struct ehci_itd, itd_list); 258 ehci->last_sitd_to_free = list_entry( 259 ehci->cached_sitd_list.prev, 260 struct ehci_sitd, sitd_list); 261 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true); 262 } 263 } 264 265 /* Wait for controller to stop using old iTDs and siTDs */ 266 static void end_free_itds(struct ehci_hcd *ehci) 267 { 268 struct ehci_itd *itd, *n; 269 struct ehci_sitd *sitd, *sn; 270 271 if (ehci->rh_state < EHCI_RH_RUNNING) { 272 ehci->last_itd_to_free = NULL; 273 ehci->last_sitd_to_free = NULL; 274 } 275 276 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) { 277 list_del(&itd->itd_list); 278 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma); 279 if (itd == ehci->last_itd_to_free) 280 break; 281 } 282 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) { 283 list_del(&sitd->sitd_list); 284 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma); 285 if (sitd == ehci->last_sitd_to_free) 286 break; 287 } 288 289 if (!list_empty(&ehci->cached_itd_list) || 290 !list_empty(&ehci->cached_sitd_list)) 291 start_free_itds(ehci); 292 } 293 294 295 /* Handle lost (or very late) IAA interrupts */ 296 static void ehci_iaa_watchdog(struct ehci_hcd *ehci) 297 { 298 if (ehci->rh_state != EHCI_RH_RUNNING) 299 return; 300 301 /* 302 * Lost IAA irqs wedge things badly; seen first with a vt8235. 303 * So we need this watchdog, but must protect it against both 304 * (a) SMP races against real IAA firing and retriggering, and 305 * (b) clean HC shutdown, when IAA watchdog was pending. 306 */ 307 if (ehci->async_iaa) { 308 u32 cmd, status; 309 310 /* If we get here, IAA is *REALLY* late. It's barely 311 * conceivable that the system is so busy that CMD_IAAD 312 * is still legitimately set, so let's be sure it's 313 * clear before we read STS_IAA. (The HC should clear 314 * CMD_IAAD when it sets STS_IAA.) 315 */ 316 cmd = ehci_readl(ehci, &ehci->regs->command); 317 318 /* 319 * If IAA is set here it either legitimately triggered 320 * after the watchdog timer expired (_way_ late, so we'll 321 * still count it as lost) ... or a silicon erratum: 322 * - VIA seems to set IAA without triggering the IRQ; 323 * - IAAD potentially cleared without setting IAA. 324 */ 325 status = ehci_readl(ehci, &ehci->regs->status); 326 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) { 327 COUNT(ehci->stats.lost_iaa); 328 ehci_writel(ehci, STS_IAA, &ehci->regs->status); 329 } 330 331 ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n", 332 status, cmd); 333 end_unlink_async(ehci); 334 } 335 } 336 337 338 /* Enable the I/O watchdog, if appropriate */ 339 static void turn_on_io_watchdog(struct ehci_hcd *ehci) 340 { 341 /* Not needed if the controller isn't running or it's already enabled */ 342 if (ehci->rh_state != EHCI_RH_RUNNING || 343 (ehci->enabled_hrtimer_events & 344 BIT(EHCI_HRTIMER_IO_WATCHDOG))) 345 return; 346 347 /* 348 * Isochronous transfers always need the watchdog. 349 * For other sorts we use it only if the flag is set. 350 */ 351 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog && 352 ehci->async_count + ehci->intr_count > 0)) 353 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true); 354 } 355 356 357 /* 358 * Handler functions for the hrtimer event types. 359 * Keep this array in the same order as the event types indexed by 360 * enum ehci_hrtimer_event in ehci.h. 361 */ 362 static void (*event_handlers[])(struct ehci_hcd *) = { 363 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */ 364 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */ 365 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */ 366 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */ 367 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */ 368 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */ 369 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */ 370 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 371 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */ 372 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */ 373 }; 374 375 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t) 376 { 377 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer); 378 ktime_t now; 379 unsigned long events; 380 unsigned long flags; 381 unsigned e; 382 383 spin_lock_irqsave(&ehci->lock, flags); 384 385 events = ehci->enabled_hrtimer_events; 386 ehci->enabled_hrtimer_events = 0; 387 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT; 388 389 /* 390 * Check each pending event. If its time has expired, handle 391 * the event; otherwise re-enable it. 392 */ 393 now = ktime_get(); 394 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) { 395 if (now.tv64 >= ehci->hr_timeouts[e].tv64) 396 event_handlers[e](ehci); 397 else 398 ehci_enable_event(ehci, e, false); 399 } 400 401 spin_unlock_irqrestore(&ehci->lock, flags); 402 return HRTIMER_NORESTART; 403 } 404