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 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */ 76 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 77 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */ 78 }; 79 80 /* Enable a pending hrtimer event */ 81 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event, 82 bool resched) 83 { 84 ktime_t *timeout = &ehci->hr_timeouts[event]; 85 86 if (resched) 87 *timeout = ktime_add(ktime_get(), 88 ktime_set(0, event_delays_ns[event])); 89 ehci->enabled_hrtimer_events |= (1 << event); 90 91 /* Track only the lowest-numbered pending event */ 92 if (event < ehci->next_hrtimer_event) { 93 ehci->next_hrtimer_event = event; 94 hrtimer_start_range_ns(&ehci->hrtimer, *timeout, 95 NSEC_PER_MSEC, HRTIMER_MODE_ABS); 96 } 97 } 98 99 100 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */ 101 static void ehci_poll_ASS(struct ehci_hcd *ehci) 102 { 103 unsigned actual, want; 104 105 /* Don't enable anything if the controller isn't running (e.g., died) */ 106 if (ehci->rh_state != EHCI_RH_RUNNING) 107 return; 108 109 want = (ehci->command & CMD_ASE) ? STS_ASS : 0; 110 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS; 111 112 if (want != actual) { 113 114 /* Poll again later, but give up after about 20 ms */ 115 if (ehci->ASS_poll_count++ < 20) { 116 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true); 117 return; 118 } 119 ehci_warn(ehci, "Waited too long for the async schedule status, giving up\n"); 120 } 121 ehci->ASS_poll_count = 0; 122 123 /* The status is up-to-date; restart or stop the schedule as needed */ 124 if (want == 0) { /* Stopped */ 125 if (ehci->async_count > 0) 126 ehci_set_command_bit(ehci, CMD_ASE); 127 128 } else { /* Running */ 129 if (ehci->async_count == 0) { 130 131 /* Turn off the schedule after a while */ 132 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC, 133 true); 134 } 135 } 136 } 137 138 /* Turn off the async schedule after a brief delay */ 139 static void ehci_disable_ASE(struct ehci_hcd *ehci) 140 { 141 ehci_clear_command_bit(ehci, CMD_ASE); 142 } 143 144 145 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */ 146 static void ehci_poll_PSS(struct ehci_hcd *ehci) 147 { 148 unsigned actual, want; 149 150 /* Don't do anything if the controller isn't running (e.g., died) */ 151 if (ehci->rh_state != EHCI_RH_RUNNING) 152 return; 153 154 want = (ehci->command & CMD_PSE) ? STS_PSS : 0; 155 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS; 156 157 if (want != actual) { 158 159 /* Poll again later, but give up after about 20 ms */ 160 if (ehci->PSS_poll_count++ < 20) { 161 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true); 162 return; 163 } 164 ehci_warn(ehci, "Waited too long for the periodic schedule status, giving up\n"); 165 } 166 ehci->PSS_poll_count = 0; 167 168 /* The status is up-to-date; restart or stop the schedule as needed */ 169 if (want == 0) { /* Stopped */ 170 if (ehci->periodic_count > 0) { 171 172 /* make sure ehci_work scans these */ 173 ehci->next_uframe = ehci_read_frame_index(ehci) 174 & ((ehci->periodic_size << 3) - 1); 175 ehci_set_command_bit(ehci, CMD_PSE); 176 } 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 } 218 219 220 /* Handle unlinked interrupt QHs once they are gone from the hardware */ 221 static void ehci_handle_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 ehci->intr_unlinking = true; 233 while (ehci->intr_unlink) { 234 struct ehci_qh *qh = ehci->intr_unlink; 235 236 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle) 237 break; 238 ehci->intr_unlink = qh->unlink_next; 239 qh->unlink_next = NULL; 240 end_unlink_intr(ehci, qh); 241 } 242 243 /* Handle remaining entries later */ 244 if (ehci->intr_unlink) { 245 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true); 246 ++ehci->intr_unlink_cycle; 247 } 248 ehci->intr_unlinking = false; 249 } 250 251 252 /* Start another free-iTDs/siTDs cycle */ 253 static void start_free_itds(struct ehci_hcd *ehci) 254 { 255 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) { 256 ehci->last_itd_to_free = list_entry( 257 ehci->cached_itd_list.prev, 258 struct ehci_itd, itd_list); 259 ehci->last_sitd_to_free = list_entry( 260 ehci->cached_sitd_list.prev, 261 struct ehci_sitd, sitd_list); 262 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true); 263 } 264 } 265 266 /* Wait for controller to stop using old iTDs and siTDs */ 267 static void end_free_itds(struct ehci_hcd *ehci) 268 { 269 struct ehci_itd *itd, *n; 270 struct ehci_sitd *sitd, *sn; 271 272 if (ehci->rh_state < EHCI_RH_RUNNING) { 273 ehci->last_itd_to_free = NULL; 274 ehci->last_sitd_to_free = NULL; 275 } 276 277 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) { 278 list_del(&itd->itd_list); 279 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma); 280 if (itd == ehci->last_itd_to_free) 281 break; 282 } 283 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) { 284 list_del(&sitd->sitd_list); 285 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma); 286 if (sitd == ehci->last_sitd_to_free) 287 break; 288 } 289 290 if (!list_empty(&ehci->cached_itd_list) || 291 !list_empty(&ehci->cached_sitd_list)) 292 start_free_itds(ehci); 293 } 294 295 296 /* Handle lost (or very late) IAA interrupts */ 297 static void ehci_iaa_watchdog(struct ehci_hcd *ehci) 298 { 299 if (ehci->rh_state != EHCI_RH_RUNNING) 300 return; 301 302 /* 303 * Lost IAA irqs wedge things badly; seen first with a vt8235. 304 * So we need this watchdog, but must protect it against both 305 * (a) SMP races against real IAA firing and retriggering, and 306 * (b) clean HC shutdown, when IAA watchdog was pending. 307 */ 308 if (ehci->async_iaa) { 309 u32 cmd, status; 310 311 /* If we get here, IAA is *REALLY* late. It's barely 312 * conceivable that the system is so busy that CMD_IAAD 313 * is still legitimately set, so let's be sure it's 314 * clear before we read STS_IAA. (The HC should clear 315 * CMD_IAAD when it sets STS_IAA.) 316 */ 317 cmd = ehci_readl(ehci, &ehci->regs->command); 318 319 /* 320 * If IAA is set here it either legitimately triggered 321 * after the watchdog timer expired (_way_ late, so we'll 322 * still count it as lost) ... or a silicon erratum: 323 * - VIA seems to set IAA without triggering the IRQ; 324 * - IAAD potentially cleared without setting IAA. 325 */ 326 status = ehci_readl(ehci, &ehci->regs->status); 327 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) { 328 COUNT(ehci->stats.lost_iaa); 329 ehci_writel(ehci, STS_IAA, &ehci->regs->status); 330 } 331 332 ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n", 333 status, cmd); 334 end_unlink_async(ehci); 335 } 336 } 337 338 339 /* 340 * Handler functions for the hrtimer event types. 341 * Keep this array in the same order as the event types indexed by 342 * enum ehci_hrtimer_event in ehci.h. 343 */ 344 static void (*event_handlers[])(struct ehci_hcd *) = { 345 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */ 346 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */ 347 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */ 348 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */ 349 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */ 350 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */ 351 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */ 352 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */ 353 }; 354 355 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t) 356 { 357 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer); 358 ktime_t now; 359 unsigned long events; 360 unsigned long flags; 361 unsigned e; 362 363 spin_lock_irqsave(&ehci->lock, flags); 364 365 events = ehci->enabled_hrtimer_events; 366 ehci->enabled_hrtimer_events = 0; 367 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT; 368 369 /* 370 * Check each pending event. If its time has expired, handle 371 * the event; otherwise re-enable it. 372 */ 373 now = ktime_get(); 374 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) { 375 if (now.tv64 >= ehci->hr_timeouts[e].tv64) 376 event_handlers[e](ehci); 377 else 378 ehci_enable_event(ehci, e, false); 379 } 380 381 spin_unlock_irqrestore(&ehci->lock, flags); 382 return HRTIMER_NORESTART; 383 } 384