acpi_timer.c revision 128543
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: head/sys/dev/acpica/acpi_timer.c 128543 2004-04-22 01:50:08Z njl $ 28 */ 29#include "opt_acpi.h" 30#include <sys/param.h> 31#include <sys/bus.h> 32#include <sys/kernel.h> 33#include <sys/sysctl.h> 34#include <sys/timetc.h> 35 36#include <machine/bus.h> 37#include <machine/resource.h> 38#include <sys/rman.h> 39 40#include "acpi.h" 41#include <dev/acpica/acpivar.h> 42#include <dev/pci/pcivar.h> 43 44/* 45 * A timecounter based on the free-running ACPI timer. 46 * 47 * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>. 48 */ 49 50/* Hooks for the ACPI CA debugging infrastructure */ 51#define _COMPONENT ACPI_TIMER 52ACPI_MODULE_NAME("TIMER") 53 54static device_t acpi_timer_dev; 55static struct resource *acpi_timer_reg; 56static bus_space_handle_t acpi_timer_bsh; 57static bus_space_tag_t acpi_timer_bst; 58 59static u_int acpi_timer_frequency = 14318182 / 4; 60 61static void acpi_timer_identify(driver_t *driver, device_t parent); 62static int acpi_timer_probe(device_t dev); 63static int acpi_timer_attach(device_t dev); 64static u_int acpi_timer_get_timecount(struct timecounter *tc); 65static u_int acpi_timer_get_timecount_safe(struct timecounter *tc); 66static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS); 67static void acpi_timer_boot_test(void); 68 69static u_int acpi_timer_read(void); 70static int acpi_timer_test(void); 71 72static device_method_t acpi_timer_methods[] = { 73 DEVMETHOD(device_identify, acpi_timer_identify), 74 DEVMETHOD(device_probe, acpi_timer_probe), 75 DEVMETHOD(device_attach, acpi_timer_attach), 76 77 {0, 0} 78}; 79 80static driver_t acpi_timer_driver = { 81 "acpi_timer", 82 acpi_timer_methods, 83 0, 84}; 85 86static devclass_t acpi_timer_devclass; 87DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, 0, 0); 88MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1); 89 90static struct timecounter acpi_timer_timecounter = { 91 acpi_timer_get_timecount_safe, /* get_timecount function */ 92 0, /* no poll_pps */ 93 0, /* no default counter_mask */ 94 0, /* no default frequency */ 95 "ACPI", /* name */ 96 1000 /* quality */ 97}; 98 99static u_int 100acpi_timer_read() 101{ 102 uint32_t tv; 103 104 tv = bus_space_read_4(acpi_timer_bst, acpi_timer_bsh, 0); 105 bus_space_barrier(acpi_timer_bst, acpi_timer_bsh, 0, 4, 106 BUS_SPACE_BARRIER_READ); 107 return (tv); 108} 109 110/* 111 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources 112 * we will be using. 113 */ 114static void 115acpi_timer_identify(driver_t *driver, device_t parent) 116{ 117 device_t dev; 118 char desc[40]; 119 u_long rlen, rstart; 120 int i, j, rid, rtype; 121 122 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__); 123 124 if (acpi_disabled("timer") || AcpiGbl_FADT == NULL) 125 return_VOID; 126 127 if ((dev = BUS_ADD_CHILD(parent, 0, "acpi_timer", 0)) == NULL) { 128 device_printf(parent, "could not add acpi_timer0\n"); 129 return_VOID; 130 } 131 acpi_timer_dev = dev; 132 133 rid = 0; 134 rlen = AcpiGbl_FADT->PmTmLen; 135 rtype = (AcpiGbl_FADT->XPmTmrBlk.AddressSpaceId) 136 ? SYS_RES_IOPORT : SYS_RES_MEMORY; 137 rstart = AcpiGbl_FADT->XPmTmrBlk.Address; 138 bus_set_resource(dev, rtype, rid, rstart, rlen); 139 acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE); 140 if (acpi_timer_reg == NULL) { 141 device_printf(dev, "couldn't allocate I/O resource (%s 0x%lx)\n", 142 rtype == SYS_RES_IOPORT ? "port" : "mem", rstart); 143 return_VOID; 144 } 145 acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg); 146 acpi_timer_bst = rman_get_bustag(acpi_timer_reg); 147 if (AcpiGbl_FADT->TmrValExt != 0) 148 acpi_timer_timecounter.tc_counter_mask = 0xffffffff; 149 else 150 acpi_timer_timecounter.tc_counter_mask = 0x00ffffff; 151 acpi_timer_timecounter.tc_frequency = acpi_timer_frequency; 152 if (testenv("debug.acpi.timer_test")) 153 acpi_timer_boot_test(); 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 acpi_timer_timecounter.tc_name = "ACPI-fast"; 165 acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount; 166 } else { 167 acpi_timer_timecounter.tc_name = "ACPI-safe"; 168 acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount_safe; 169 } 170 tc_init(&acpi_timer_timecounter); 171 172 sprintf(desc, "%d-bit timer at 3.579545MHz", 173 AcpiGbl_FADT->TmrValExt ? 32 : 24); 174 device_set_desc_copy(dev, desc); 175 176 return_VOID; 177} 178 179static int 180acpi_timer_probe(device_t dev) 181{ 182 if (dev == acpi_timer_dev) 183 return (0); 184 185 return (ENXIO); 186} 187 188static int 189acpi_timer_attach(device_t dev) 190{ 191 return (0); 192} 193 194/* 195 * Fetch current time value from reliable hardware. 196 */ 197static u_int 198acpi_timer_get_timecount(struct timecounter *tc) 199{ 200 return (acpi_timer_read()); 201} 202 203/* 204 * Fetch current time value from hardware that may not correctly 205 * latch the counter. We need to read until we have three monotonic 206 * samples and then use the middle one, otherwise we are not protected 207 * against the fact that the bits can be wrong in two directions. If 208 * we only cared about monosity, two reads would be enough. 209 */ 210static u_int 211acpi_timer_get_timecount_safe(struct timecounter *tc) 212{ 213 u_int u1, u2, u3; 214 215 u2 = acpi_timer_read(); 216 u3 = acpi_timer_read(); 217 do { 218 u1 = u2; 219 u2 = u3; 220 u3 = acpi_timer_read(); 221 } while (u1 > u2 || u2 > u3); 222 223 return (u2); 224} 225 226/* 227 * Timecounter freqency adjustment interface. 228 */ 229static int 230acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS) 231{ 232 int error; 233 u_int freq; 234 235 if (acpi_timer_timecounter.tc_frequency == 0) 236 return (EOPNOTSUPP); 237 freq = acpi_timer_frequency; 238 error = sysctl_handle_int(oidp, &freq, sizeof(freq), req); 239 if (error == 0 && req->newptr != NULL) { 240 acpi_timer_frequency = freq; 241 acpi_timer_timecounter.tc_frequency = acpi_timer_frequency; 242 } 243 244 return (error); 245} 246 247SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW, 248 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", ""); 249 250/* 251 * Some ACPI timers are known or believed to suffer from implementation 252 * problems which can lead to erroneous values being read. This function 253 * tests for consistent results from the timer and returns 1 if it believes 254 * the timer is consistent, otherwise it returns 0. 255 * 256 * It appears the cause is that the counter is not latched to the PCI bus 257 * clock when read: 258 * 259 * ] 20. ACPI Timer Errata 260 * ] 261 * ] Problem: The power management timer may return improper result when 262 * ] read. Although the timer value settles properly after incrementing, 263 * ] while incrementing there is a 3nS window every 69.8nS where the 264 * ] timer value is indeterminate (a 4.2% chance that the data will be 265 * ] incorrect when read). As a result, the ACPI free running count up 266 * ] timer specification is violated due to erroneous reads. Implication: 267 * ] System hangs due to the "inaccuracy" of the timer when used by 268 * ] software for time critical events and delays. 269 * ] 270 * ] Workaround: Read the register twice and compare. 271 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed 272 * ] in the PIIX4M. 273 */ 274#define N 2000 275static int 276acpi_timer_test() 277{ 278 uint32_t last, this; 279 int min, max, n, delta; 280 281 min = 10000000; 282 max = 0; 283 last = acpi_timer_read(); 284 for (n = 0; n < N; n++) { 285 this = acpi_timer_read(); 286 delta = acpi_TimerDelta(this, last); 287 if (delta > max) 288 max = delta; 289 else if (delta < min) 290 min = delta; 291 last = this; 292 } 293 if (max - min > 2) 294 n = 0; 295 else if (min < 0 || max == 0) 296 n = 0; 297 else 298 n = 1; 299 if (bootverbose) { 300 printf("ACPI timer looks %s min = %d, max = %d, width = %d\n", 301 n ? "GOOD" : "BAD ", 302 min, max, max - min); 303 } 304 305 return (n); 306} 307#undef N 308 309/* 310 * Test harness for verifying ACPI timer behaviour. 311 * Boot with debug.acpi.timer_test set to invoke this. 312 */ 313static void 314acpi_timer_boot_test(void) 315{ 316 uint32_t u1, u2, u3; 317 318 u1 = acpi_timer_read(); 319 u2 = acpi_timer_read(); 320 u3 = acpi_timer_read(); 321 322 device_printf(acpi_timer_dev, "timer test in progress, reboot to quit.\n"); 323 for (;;) { 324 /* 325 * The failure case is where u3 > u1, but u2 does not fall between 326 * the two, ie. it contains garbage. 327 */ 328 if (u3 > u1) { 329 if (u2 < u1 || u2 > u3) 330 device_printf(acpi_timer_dev, 331 "timer is not monotonic: 0x%08x,0x%08x,0x%08x\n", 332 u1, u2, u3); 333 } 334 u1 = u2; 335 u2 = u3; 336 u3 = acpi_timer_read(); 337 } 338} 339