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 .gpri = KOBJ_GPRI_ACPI+2 97 }; 98 99 static devclass_t acpi_timer_devclass; 100 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL); 101 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1); 102 103 /* 104 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources 105 * we will be using. 106 */ 107 static int 108 acpi_timer_identify(driver_t *driver, device_t parent) 109 { 110 device_t dev; 111 112 /* 113 * Just try once, do nothing if the 'acpi' bus is rescanned. 114 */ 115 if (device_get_state(parent) == DS_ATTACHED) 116 return (0); 117 118 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 119 120 if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) || 121 acpi_timer_dev) 122 return (ENXIO); 123 124 if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) { 125 device_printf(parent, "could not add acpi_timer0\n"); 126 return (ENXIO); 127 } 128 acpi_timer_dev = dev; 129 130 return (0); 131 } 132 133 static int 134 acpi_timer_probe(device_t dev) 135 { 136 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 137 138 if (dev != acpi_timer_dev) 139 return (ENXIO); 140 141 if (ACPI_FAILURE(AcpiGetTimerResolution(&acpi_timer_resolution))) 142 return (ENXIO); 143 144 return (0); 145 } 146 147 static int 148 acpi_timer_attach(device_t dev) 149 { 150 char desc[40]; 151 int i, j; 152 153 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 154 155 /* 156 * If all tests of the counter succeed, use the ACPI-fast method. If 157 * at least one failed, default to using the safe routine, which reads 158 * the timer multiple times to get a consistent value before returning. 159 */ 160 j = 0; 161 for (i = 0; i < 10; i++) 162 j += acpi_timer_test(); 163 if (j == 10) { 164 if (acpi_timer_resolution == 32) { 165 acpi_cputimer.name = "ACPI-fast"; 166 acpi_cputimer.count = acpi_timer_get_timecount; 167 } else { 168 acpi_cputimer.name = "ACPI-fast24"; 169 acpi_cputimer.count = acpi_timer_get_timecount24; 170 } 171 } else { 172 if (acpi_timer_resolution == 32) 173 acpi_cputimer.name = "ACPI-safe"; 174 else 175 acpi_cputimer.name = "ACPI-safe24"; 176 acpi_cputimer.count = acpi_timer_get_timecount_safe; 177 } 178 179 ksprintf(desc, "%u-bit timer at 3.579545MHz", acpi_timer_resolution); 180 device_set_desc_copy(dev, desc); 181 182 cputimer_register(&acpi_cputimer); 183 cputimer_select(&acpi_cputimer, 0); 184 185 return (0); 186 } 187 188 /* 189 * Construct the timer. Adjust the base so the system clock does not 190 * jump weirdly. 191 */ 192 static void 193 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock) 194 { 195 timer->base = 0; 196 timer->base = oldclock - acpi_timer_get_timecount_safe(); 197 } 198 199 /* 200 * Fetch current time value from reliable hardware. 201 * 202 * The cputimer interface requires a 32 bit return value. If the ACPI timer 203 * is only 24 bits then we have to keep track of the upper 8 bits on our 204 * own. 205 * 206 * XXX we could probably get away with using a per-cpu field for this and 207 * just use interrupt disablement instead of clock_lock. 208 */ 209 static sysclock_t 210 acpi_timer_get_timecount24(void) 211 { 212 sysclock_t counter; 213 214 clock_lock(); 215 AcpiGetTimer(&counter); 216 if (counter < acpi_last_counter) 217 acpi_cputimer.base += 0x01000000; 218 acpi_last_counter = counter; 219 counter += acpi_cputimer.base; 220 clock_unlock(); 221 return (counter); 222 } 223 224 static sysclock_t 225 acpi_timer_get_timecount(void) 226 { 227 sysclock_t counter; 228 229 AcpiGetTimer(&counter); 230 return (counter + acpi_cputimer.base); 231 } 232 233 /* 234 * Fetch current time value from hardware that may not correctly 235 * latch the counter. We need to read until we have three monotonic 236 * samples and then use the middle one, otherwise we are not protected 237 * against the fact that the bits can be wrong in two directions. If 238 * we only cared about monosity, two reads would be enough. 239 */ 240 static sysclock_t 241 acpi_timer_get_timecount_safe(void) 242 { 243 u_int u1, u2, u3; 244 245 if (acpi_timer_resolution != 32) 246 clock_lock(); 247 248 AcpiGetTimer(&u2); 249 AcpiGetTimer(&u3); 250 do { 251 u1 = u2; 252 u2 = u3; 253 AcpiGetTimer(&u3); 254 } while (u1 > u2 || u2 > u3); 255 256 if (acpi_timer_resolution != 32) { 257 if (u2 < acpi_last_counter) 258 acpi_cputimer.base += 0x01000000; 259 acpi_last_counter = u2; 260 clock_unlock(); 261 } 262 return (u2 + acpi_cputimer.base); 263 } 264 265 /* 266 * Timecounter freqency adjustment interface. 267 */ 268 static int 269 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS) 270 { 271 int error; 272 u_int freq; 273 274 if (acpi_cputimer.freq == 0) 275 return (EOPNOTSUPP); 276 freq = acpi_cputimer.freq; 277 error = sysctl_handle_int(oidp, &freq, 0, req); 278 if (error == 0 && req->newptr != NULL) 279 cputimer_set_frequency(&acpi_cputimer, freq); 280 281 return (error); 282 } 283 284 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW, 285 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency"); 286 287 /* 288 * Some ACPI timers are known or believed to suffer from implementation 289 * problems which can lead to erroneous values being read. This function 290 * tests for consistent results from the timer and returns 1 if it believes 291 * the timer is consistent, otherwise it returns 0. 292 * 293 * It appears the cause is that the counter is not latched to the PCI bus 294 * clock when read: 295 * 296 * ] 20. ACPI Timer Errata 297 * ] 298 * ] Problem: The power management timer may return improper result when 299 * ] read. Although the timer value settles properly after incrementing, 300 * ] while incrementing there is a 3nS window every 69.8nS where the 301 * ] timer value is indeterminate (a 4.2% chance that the data will be 302 * ] incorrect when read). As a result, the ACPI free running count up 303 * ] timer specification is violated due to erroneous reads. Implication: 304 * ] System hangs due to the "inaccuracy" of the timer when used by 305 * ] software for time critical events and delays. 306 * ] 307 * ] Workaround: Read the register twice and compare. 308 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed 309 * ] in the PIIX4M. 310 */ 311 312 static int 313 acpi_timer_test(void) 314 { 315 uint32_t last, this; 316 int min, max, max2, n, delta; 317 register_t s; 318 319 min = INT32_MAX; 320 max = max2 = 0; 321 322 /* Test the timer with interrupts disabled to get accurate results. */ 323 #if defined(__x86_64__) 324 s = read_rflags(); 325 #else 326 #error "no read_*flags" 327 #endif 328 cpu_disable_intr(); 329 AcpiGetTimer(&last); 330 for (n = 0; n < 2000; n++) { 331 AcpiGetTimer(&this); 332 delta = acpi_TimerDelta(this, last); 333 if (delta > max) { 334 max2 = max; 335 max = delta; 336 } else if (delta > max2) { 337 max2 = delta; 338 } 339 if (delta < min) 340 min = delta; 341 last = this; 342 } 343 /* cpu_enable_intr(); restored to original by write_rflags() */ 344 #if defined(__x86_64__) 345 write_rflags(s); 346 #else 347 #error "no read_*flags" 348 #endif 349 350 delta = max2 - min; 351 if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE) 352 n = 0; 353 else if (min < 0 || max == 0 || max2 == 0) 354 n = 0; 355 else 356 n = 1; 357 if (bootverbose) { 358 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n", 359 n ? "GOOD" : "BAD ", 360 min, max, max - min); 361 } 362 363 return (n); 364 } 365