1 /*- 2 * Copyright (c) 2000, 2001 Michael Smith 3 * Copyright (c) 2000 BSDi 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 * $FreeBSD: src/sys/dev/acpica/acpi_timer.c,v 1.35 2004/07/22 05:42:14 njl Exp $ 28 */ 29 #include "opt_acpi.h" 30 #include <sys/param.h> 31 #include <sys/bus.h> 32 #include <sys/kernel.h> 33 #include <sys/module.h> 34 #include <sys/sysctl.h> 35 #include <sys/systimer.h> 36 #include <sys/rman.h> 37 38 #include <machine/lock.h> 39 #include <bus/pci/pcivar.h> 40 41 #include "acpi.h" 42 #include "accommon.h" 43 #include "acpivar.h" 44 45 /* 46 * A timecounter based on the free-running ACPI timer. 47 * 48 * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>. 49 */ 50 51 /* Hooks for the ACPICA debugging infrastructure */ 52 #define _COMPONENT ACPI_TIMER 53 ACPI_MODULE_NAME("TIMER") 54 55 static device_t acpi_timer_dev; 56 static UINT32 acpi_timer_resolution; 57 static sysclock_t acpi_last_counter; 58 59 static sysclock_t acpi_timer_get_timecount(void); 60 static sysclock_t acpi_timer_get_timecount24(void); 61 static sysclock_t acpi_timer_get_timecount_safe(void); 62 static void acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock); 63 64 static struct cputimer acpi_cputimer = { 65 .next = SLIST_ENTRY_INITIALIZER, 66 .name = "ACPI", 67 .pri = CPUTIMER_PRI_ACPI, 68 .type = CPUTIMER_ACPI, 69 .count = acpi_timer_get_timecount_safe, 70 .fromhz = cputimer_default_fromhz, 71 .fromus = cputimer_default_fromus, 72 .construct = acpi_timer_construct, 73 .destruct = cputimer_default_destruct, 74 .freq = ACPI_PM_TIMER_FREQUENCY 75 }; 76 77 static int acpi_timer_identify(driver_t *driver, device_t parent); 78 static int acpi_timer_probe(device_t dev); 79 static int acpi_timer_attach(device_t dev); 80 static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS); 81 82 static int acpi_timer_test(void); 83 84 static device_method_t acpi_timer_methods[] = { 85 DEVMETHOD(device_identify, acpi_timer_identify), 86 DEVMETHOD(device_probe, acpi_timer_probe), 87 DEVMETHOD(device_attach, acpi_timer_attach), 88 89 DEVMETHOD_END 90 }; 91 92 static driver_t acpi_timer_driver = { 93 "acpi_timer", 94 acpi_timer_methods, 95 0, 96 }; 97 98 static devclass_t acpi_timer_devclass; 99 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL); 100 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1); 101 102 /* 103 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources 104 * we will be using. 105 */ 106 static int 107 acpi_timer_identify(driver_t *driver, device_t parent) 108 { 109 device_t dev; 110 111 /* 112 * Just try once, do nothing if the 'acpi' bus is rescanned. 113 */ 114 if (device_get_state(parent) == DS_ATTACHED) 115 return (0); 116 117 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 118 119 if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) || 120 acpi_timer_dev) 121 return (ENXIO); 122 123 if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) { 124 device_printf(parent, "could not add acpi_timer0\n"); 125 return (ENXIO); 126 } 127 acpi_timer_dev = dev; 128 129 return (0); 130 } 131 132 static int 133 acpi_timer_probe(device_t dev) 134 { 135 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 136 137 if (dev != acpi_timer_dev) 138 return (ENXIO); 139 140 if (ACPI_FAILURE(AcpiGetTimerResolution(&acpi_timer_resolution))) 141 return (ENXIO); 142 143 return (0); 144 } 145 146 static int 147 acpi_timer_attach(device_t dev) 148 { 149 char desc[40]; 150 int i, j; 151 152 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 153 154 /* 155 * If all tests of the counter succeed, use the ACPI-fast method. If 156 * at least one failed, default to using the safe routine, which reads 157 * the timer multiple times to get a consistent value before returning. 158 */ 159 j = 0; 160 for (i = 0; i < 10; i++) 161 j += acpi_timer_test(); 162 if (j == 10) { 163 if (acpi_timer_resolution == 32) { 164 acpi_cputimer.name = "ACPI-fast"; 165 acpi_cputimer.count = acpi_timer_get_timecount; 166 } else { 167 acpi_cputimer.name = "ACPI-fast24"; 168 acpi_cputimer.count = acpi_timer_get_timecount24; 169 } 170 } else { 171 if (acpi_timer_resolution == 32) 172 acpi_cputimer.name = "ACPI-safe"; 173 else 174 acpi_cputimer.name = "ACPI-safe24"; 175 acpi_cputimer.count = acpi_timer_get_timecount_safe; 176 } 177 178 ksprintf(desc, "%u-bit timer at 3.579545MHz", acpi_timer_resolution); 179 device_set_desc_copy(dev, desc); 180 181 cputimer_register(&acpi_cputimer); 182 cputimer_select(&acpi_cputimer, 0); 183 184 return (0); 185 } 186 187 /* 188 * Construct the timer. Adjust the base so the system clock does not 189 * jump weirdly. 190 */ 191 static void 192 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock) 193 { 194 timer->base = 0; 195 timer->base = oldclock - acpi_timer_get_timecount_safe(); 196 } 197 198 /* 199 * Fetch current time value from reliable hardware. 200 * 201 * The cputimer interface requires a 32 bit return value. If the ACPI timer 202 * is only 24 bits then we have to keep track of the upper 8 bits on our 203 * own. 204 * 205 * XXX we could probably get away with using a per-cpu field for this and 206 * just use interrupt disablement instead of clock_lock. 207 */ 208 static sysclock_t 209 acpi_timer_get_timecount24(void) 210 { 211 sysclock_t counter; 212 213 clock_lock(); 214 AcpiGetTimer(&counter); 215 if (counter < acpi_last_counter) 216 acpi_cputimer.base += 0x01000000; 217 acpi_last_counter = counter; 218 counter += acpi_cputimer.base; 219 clock_unlock(); 220 return (counter); 221 } 222 223 static sysclock_t 224 acpi_timer_get_timecount(void) 225 { 226 sysclock_t counter; 227 228 AcpiGetTimer(&counter); 229 return (counter + acpi_cputimer.base); 230 } 231 232 /* 233 * Fetch current time value from hardware that may not correctly 234 * latch the counter. We need to read until we have three monotonic 235 * samples and then use the middle one, otherwise we are not protected 236 * against the fact that the bits can be wrong in two directions. If 237 * we only cared about monosity, two reads would be enough. 238 */ 239 static sysclock_t 240 acpi_timer_get_timecount_safe(void) 241 { 242 u_int u1, u2, u3; 243 244 if (acpi_timer_resolution != 32) 245 clock_lock(); 246 247 AcpiGetTimer(&u2); 248 AcpiGetTimer(&u3); 249 do { 250 u1 = u2; 251 u2 = u3; 252 AcpiGetTimer(&u3); 253 } while (u1 > u2 || u2 > u3); 254 255 if (acpi_timer_resolution != 32) { 256 if (u2 < acpi_last_counter) 257 acpi_cputimer.base += 0x01000000; 258 acpi_last_counter = u2; 259 clock_unlock(); 260 } 261 return (u2 + acpi_cputimer.base); 262 } 263 264 /* 265 * Timecounter freqency adjustment interface. 266 */ 267 static int 268 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS) 269 { 270 int error; 271 u_int freq; 272 273 if (acpi_cputimer.freq == 0) 274 return (EOPNOTSUPP); 275 freq = acpi_cputimer.freq; 276 error = sysctl_handle_int(oidp, &freq, 0, req); 277 if (error == 0 && req->newptr != NULL) 278 cputimer_set_frequency(&acpi_cputimer, freq); 279 280 return (error); 281 } 282 283 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW, 284 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency"); 285 286 /* 287 * Some ACPI timers are known or believed to suffer from implementation 288 * problems which can lead to erroneous values being read. This function 289 * tests for consistent results from the timer and returns 1 if it believes 290 * the timer is consistent, otherwise it returns 0. 291 * 292 * It appears the cause is that the counter is not latched to the PCI bus 293 * clock when read: 294 * 295 * ] 20. ACPI Timer Errata 296 * ] 297 * ] Problem: The power management timer may return improper result when 298 * ] read. Although the timer value settles properly after incrementing, 299 * ] while incrementing there is a 3nS window every 69.8nS where the 300 * ] timer value is indeterminate (a 4.2% chance that the data will be 301 * ] incorrect when read). As a result, the ACPI free running count up 302 * ] timer specification is violated due to erroneous reads. Implication: 303 * ] System hangs due to the "inaccuracy" of the timer when used by 304 * ] software for time critical events and delays. 305 * ] 306 * ] Workaround: Read the register twice and compare. 307 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed 308 * ] in the PIIX4M. 309 */ 310 311 static int 312 acpi_timer_test(void) 313 { 314 uint32_t last, this; 315 int min, max, max2, n, delta; 316 register_t s; 317 318 min = INT32_MAX; 319 max = max2 = 0; 320 321 /* Test the timer with interrupts disabled to get accurate results. */ 322 #if defined(__x86_64__) 323 s = read_rflags(); 324 #else 325 #error "no read_*flags" 326 #endif 327 cpu_disable_intr(); 328 AcpiGetTimer(&last); 329 for (n = 0; n < 2000; n++) { 330 AcpiGetTimer(&this); 331 delta = acpi_TimerDelta(this, last); 332 if (delta > max) { 333 max2 = max; 334 max = delta; 335 } else if (delta > max2) { 336 max2 = delta; 337 } 338 if (delta < min) 339 min = delta; 340 last = this; 341 } 342 /* cpu_enable_intr(); restored to original by write_rflags() */ 343 #if defined(__x86_64__) 344 write_rflags(s); 345 #else 346 #error "no read_*flags" 347 #endif 348 349 delta = max2 - min; 350 if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE) 351 n = 0; 352 else if (min < 0 || max == 0 || max2 == 0) 353 n = 0; 354 else 355 n = 1; 356 if (bootverbose) { 357 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n", 358 n ? "GOOD" : "BAD ", 359 min, max, max - min); 360 } 361 362 return (n); 363 } 364