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john stultz5d0cf412006-06-26 00:25:12 -07001/*
2 * linux/drivers/clocksource/acpi_pm.c
3 *
4 * This file contains the ACPI PM based clocksource.
5 *
6 * This code was largely moved from the i386 timer_pm.c file
7 * which was (C) Dominik Brodowski <linux@brodo.de> 2003
8 * and contained the following comments:
9 *
10 * Driver to use the Power Management Timer (PMTMR) available in some
11 * southbridges as primary timing source for the Linux kernel.
12 *
13 * Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
14 * timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
15 *
16 * This file is licensed under the GPL v2.
17 */
18
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080019#include <linux/acpi_pmtmr.h>
john stultz5d0cf412006-06-26 00:25:12 -070020#include <linux/clocksource.h>
21#include <linux/errno.h>
22#include <linux/init.h>
23#include <linux/pci.h>
Dominik Brodowski4ab6a212008-09-05 14:05:35 -070024#include <linux/delay.h>
john stultz5d0cf412006-06-26 00:25:12 -070025#include <asm/io.h>
26
john stultz5d0cf412006-06-26 00:25:12 -070027/*
28 * The I/O port the PMTMR resides at.
29 * The location is detected during setup_arch(),
Daniel Walker8ce8e2f2007-04-25 14:27:06 -040030 * in arch/i386/kernel/acpi/boot.c
john stultz5d0cf412006-06-26 00:25:12 -070031 */
Andreas Mohr7d622d42006-06-26 00:25:14 -070032u32 pmtmr_ioport __read_mostly;
john stultz5d0cf412006-06-26 00:25:12 -070033
john stultz5d0cf412006-06-26 00:25:12 -070034static inline u32 read_pmtmr(void)
35{
36 /* mask the output to 24 bits */
37 return inl(pmtmr_ioport) & ACPI_PM_MASK;
38}
39
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080040u32 acpi_pm_read_verified(void)
john stultz5d0cf412006-06-26 00:25:12 -070041{
42 u32 v1 = 0, v2 = 0, v3 = 0;
43
44 /*
45 * It has been reported that because of various broken
46 * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM clock
Andreas Mohr7d622d42006-06-26 00:25:14 -070047 * source is not latched, you must read it multiple
john stultz5d0cf412006-06-26 00:25:12 -070048 * times to ensure a safe value is read:
49 */
50 do {
51 v1 = read_pmtmr();
52 v2 = read_pmtmr();
53 v3 = read_pmtmr();
Daniel Walker78f32662006-10-21 10:24:10 -070054 } while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
55 || (v3 > v1 && v3 < v2)));
john stultz5d0cf412006-06-26 00:25:12 -070056
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080057 return v2;
58}
59
60static cycle_t acpi_pm_read_slow(void)
61{
62 return (cycle_t)acpi_pm_read_verified();
john stultz5d0cf412006-06-26 00:25:12 -070063}
64
65static cycle_t acpi_pm_read(void)
66{
67 return (cycle_t)read_pmtmr();
68}
69
70static struct clocksource clocksource_acpi_pm = {
71 .name = "acpi_pm",
72 .rating = 200,
73 .read = acpi_pm_read,
74 .mask = (cycle_t)ACPI_PM_MASK,
Alessio Igor Bogani7b0b8202007-07-21 17:11:19 +020075 .mult = 0, /*to be calculated*/
john stultz5d0cf412006-06-26 00:25:12 -070076 .shift = 22,
Thomas Gleixner73b08d22007-02-16 01:27:36 -080077 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
78
john stultz5d0cf412006-06-26 00:25:12 -070079};
80
81
82#ifdef CONFIG_PCI
Daniel Walkerf5f1a242006-12-10 02:21:33 -080083static int __devinitdata acpi_pm_good;
john stultz5d0cf412006-06-26 00:25:12 -070084static int __init acpi_pm_good_setup(char *__str)
85{
Daniel Walkerf5f1a242006-12-10 02:21:33 -080086 acpi_pm_good = 1;
87 return 1;
john stultz5d0cf412006-06-26 00:25:12 -070088}
89__setup("acpi_pm_good", acpi_pm_good_setup);
90
91static inline void acpi_pm_need_workaround(void)
92{
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080093 clocksource_acpi_pm.read = acpi_pm_read_slow;
john stultz1ff100d2007-03-26 21:32:19 -080094 clocksource_acpi_pm.rating = 120;
john stultz5d0cf412006-06-26 00:25:12 -070095}
96
97/*
98 * PIIX4 Errata:
99 *
100 * The power management timer may return improper results when read.
101 * Although the timer value settles properly after incrementing,
102 * while incrementing there is a 3 ns window every 69.8 ns where the
103 * timer value is indeterminate (a 4.2% chance that the data will be
104 * incorrect when read). As a result, the ACPI free running count up
105 * timer specification is violated due to erroneous reads.
106 */
107static void __devinit acpi_pm_check_blacklist(struct pci_dev *dev)
108{
john stultz5d0cf412006-06-26 00:25:12 -0700109 if (acpi_pm_good)
110 return;
111
john stultz5d0cf412006-06-26 00:25:12 -0700112 /* the bug has been fixed in PIIX4M */
Auke Kok44c10132007-06-08 15:46:36 -0700113 if (dev->revision < 3) {
john stultz5d0cf412006-06-26 00:25:12 -0700114 printk(KERN_WARNING "* Found PM-Timer Bug on the chipset."
115 " Due to workarounds for a bug,\n"
116 "* this clock source is slow. Consider trying"
117 " other clock sources\n");
118
119 acpi_pm_need_workaround();
120 }
121}
122DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3,
123 acpi_pm_check_blacklist);
124
125static void __devinit acpi_pm_check_graylist(struct pci_dev *dev)
126{
127 if (acpi_pm_good)
128 return;
129
130 printk(KERN_WARNING "* The chipset may have PM-Timer Bug. Due to"
131 " workarounds for a bug,\n"
132 "* this clock source is slow. If you are sure your timer"
133 " does not have\n"
134 "* this bug, please use \"acpi_pm_good\" to disable the"
135 " workaround\n");
136
137 acpi_pm_need_workaround();
138}
139DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801DB_0,
140 acpi_pm_check_graylist);
Daniel Walker78f32662006-10-21 10:24:10 -0700141DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
142 acpi_pm_check_graylist);
john stultz5d0cf412006-06-26 00:25:12 -0700143#endif
144
john stultz562f9c52006-12-08 02:36:02 -0800145#ifndef CONFIG_X86_64
146#include "mach_timer.h"
147#define PMTMR_EXPECTED_RATE \
148 ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
149/*
150 * Some boards have the PMTMR running way too fast. We check
151 * the PMTMR rate against PIT channel 2 to catch these cases.
152 */
153static int verify_pmtmr_rate(void)
154{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700155 cycle_t value1, value2;
john stultz562f9c52006-12-08 02:36:02 -0800156 unsigned long count, delta;
157
158 mach_prepare_counter();
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700159 value1 = clocksource_acpi_pm.read();
john stultz562f9c52006-12-08 02:36:02 -0800160 mach_countup(&count);
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700161 value2 = clocksource_acpi_pm.read();
john stultz562f9c52006-12-08 02:36:02 -0800162 delta = (value2 - value1) & ACPI_PM_MASK;
163
164 /* Check that the PMTMR delta is within 5% of what we expect */
165 if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
166 delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
167 printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% "
168 "of normal - aborting.\n",
169 100UL * delta / PMTMR_EXPECTED_RATE);
170 return -1;
171 }
172
173 return 0;
174}
175#else
176#define verify_pmtmr_rate() (0)
177#endif
john stultz5d0cf412006-06-26 00:25:12 -0700178
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700179/* Number of monotonicity checks to perform during initialization */
180#define ACPI_PM_MONOTONICITY_CHECKS 10
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200181/* Number of reads we try to get two different values */
182#define ACPI_PM_READ_CHECKS 10000
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700183
john stultz5d0cf412006-06-26 00:25:12 -0700184static int __init init_acpi_pm_clocksource(void)
185{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700186 cycle_t value1, value2;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200187 unsigned int i, j = 0;
john stultz5d0cf412006-06-26 00:25:12 -0700188
189 if (!pmtmr_ioport)
190 return -ENODEV;
191
192 clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
193 clocksource_acpi_pm.shift);
194
195 /* "verify" this timing source: */
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700196 for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) {
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200197 udelay(100 * j);
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700198 value1 = clocksource_acpi_pm.read();
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200199 for (i = 0; i < ACPI_PM_READ_CHECKS; i++) {
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700200 value2 = clocksource_acpi_pm.read();
201 if (value2 == value1)
202 continue;
203 if (value2 > value1)
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700204 break;
205 if ((value2 < value1) && ((value2) < 0xFFF))
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700206 break;
207 printk(KERN_INFO "PM-Timer had inconsistent results:"
208 " 0x%#llx, 0x%#llx - aborting.\n",
209 value1, value2);
210 return -EINVAL;
211 }
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200212 if (i == ACPI_PM_READ_CHECKS) {
213 printk(KERN_INFO "PM-Timer failed consistency check "
214 " (0x%#llx) - aborting.\n", value1);
215 return -ENODEV;
216 }
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700217 }
218
john stultz562f9c52006-12-08 02:36:02 -0800219 if (verify_pmtmr_rate() != 0)
220 return -ENODEV;
221
john stultza2752542006-06-26 00:25:14 -0700222 return clocksource_register(&clocksource_acpi_pm);
john stultz5d0cf412006-06-26 00:25:12 -0700223}
224
john stultz6bb74df2007-03-05 00:30:50 -0800225/* We use fs_initcall because we want the PCI fixups to have run
226 * but we still need to load before device_initcall
227 */
228fs_initcall(init_acpi_pm_clocksource);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200229
230/*
231 * Allow an override of the IOPort. Stupid BIOSes do not tell us about
232 * the PMTimer, but we might know where it is.
233 */
234static int __init parse_pmtmr(char *arg)
235{
236 unsigned long base;
237
238 if (strict_strtoul(arg, 16, &base))
239 return -EINVAL;
240
Linus Torvalds14351762008-07-15 11:01:39 -0700241 printk(KERN_INFO "PMTMR IOPort override: 0x%04x -> 0x%04lx\n",
Randy Dunlap38032f72008-07-11 12:57:31 -0700242 (unsigned int)pmtmr_ioport, base);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200243 pmtmr_ioport = base;
244
245 return 1;
246}
247__setup("pmtmr=", parse_pmtmr);