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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>
Arnd Bergmann08604bd2009-06-16 15:31:12 -070021#include <linux/timex.h>
john stultz5d0cf412006-06-26 00:25:12 -070022#include <linux/errno.h>
23#include <linux/init.h>
24#include <linux/pci.h>
Dominik Brodowski4ab6a212008-09-05 14:05:35 -070025#include <linux/delay.h>
john stultz5d0cf412006-06-26 00:25:12 -070026#include <asm/io.h>
27
john stultz5d0cf412006-06-26 00:25:12 -070028/*
29 * The I/O port the PMTMR resides at.
30 * The location is detected during setup_arch(),
Daniel Walker8ce8e2f2007-04-25 14:27:06 -040031 * in arch/i386/kernel/acpi/boot.c
john stultz5d0cf412006-06-26 00:25:12 -070032 */
Andreas Mohr7d622d42006-06-26 00:25:14 -070033u32 pmtmr_ioport __read_mostly;
john stultz5d0cf412006-06-26 00:25:12 -070034
john stultz5d0cf412006-06-26 00:25:12 -070035static inline u32 read_pmtmr(void)
36{
37 /* mask the output to 24 bits */
38 return inl(pmtmr_ioport) & ACPI_PM_MASK;
39}
40
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080041u32 acpi_pm_read_verified(void)
john stultz5d0cf412006-06-26 00:25:12 -070042{
43 u32 v1 = 0, v2 = 0, v3 = 0;
44
45 /*
46 * It has been reported that because of various broken
47 * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM clock
Andreas Mohr7d622d42006-06-26 00:25:14 -070048 * source is not latched, you must read it multiple
john stultz5d0cf412006-06-26 00:25:12 -070049 * times to ensure a safe value is read:
50 */
51 do {
52 v1 = read_pmtmr();
53 v2 = read_pmtmr();
54 v3 = read_pmtmr();
Daniel Walker78f32662006-10-21 10:24:10 -070055 } while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
56 || (v3 > v1 && v3 < v2)));
john stultz5d0cf412006-06-26 00:25:12 -070057
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080058 return v2;
59}
60
Magnus Damm8e196082009-04-21 12:24:00 -070061static cycle_t acpi_pm_read(struct clocksource *cs)
john stultz5d0cf412006-06-26 00:25:12 -070062{
63 return (cycle_t)read_pmtmr();
64}
65
66static struct clocksource clocksource_acpi_pm = {
67 .name = "acpi_pm",
68 .rating = 200,
69 .read = acpi_pm_read,
70 .mask = (cycle_t)ACPI_PM_MASK,
Alessio Igor Bogani7b0b8202007-07-21 17:11:19 +020071 .mult = 0, /*to be calculated*/
john stultz5d0cf412006-06-26 00:25:12 -070072 .shift = 22,
Thomas Gleixner73b08d22007-02-16 01:27:36 -080073 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
74
john stultz5d0cf412006-06-26 00:25:12 -070075};
76
77
78#ifdef CONFIG_PCI
Daniel Walkerf5f1a242006-12-10 02:21:33 -080079static int __devinitdata acpi_pm_good;
john stultz5d0cf412006-06-26 00:25:12 -070080static int __init acpi_pm_good_setup(char *__str)
81{
Daniel Walkerf5f1a242006-12-10 02:21:33 -080082 acpi_pm_good = 1;
83 return 1;
john stultz5d0cf412006-06-26 00:25:12 -070084}
85__setup("acpi_pm_good", acpi_pm_good_setup);
86
Magnus Damm8e196082009-04-21 12:24:00 -070087static cycle_t acpi_pm_read_slow(struct clocksource *cs)
Bjorn Helgaas0a57b782008-12-01 14:18:12 -080088{
89 return (cycle_t)acpi_pm_read_verified();
90}
91
john stultz5d0cf412006-06-26 00:25:12 -070092static inline void acpi_pm_need_workaround(void)
93{
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080094 clocksource_acpi_pm.read = acpi_pm_read_slow;
john stultz1ff100d2007-03-26 21:32:19 -080095 clocksource_acpi_pm.rating = 120;
john stultz5d0cf412006-06-26 00:25:12 -070096}
97
98/*
99 * PIIX4 Errata:
100 *
101 * The power management timer may return improper results when read.
102 * Although the timer value settles properly after incrementing,
103 * while incrementing there is a 3 ns window every 69.8 ns where the
104 * timer value is indeterminate (a 4.2% chance that the data will be
105 * incorrect when read). As a result, the ACPI free running count up
106 * timer specification is violated due to erroneous reads.
107 */
108static void __devinit acpi_pm_check_blacklist(struct pci_dev *dev)
109{
john stultz5d0cf412006-06-26 00:25:12 -0700110 if (acpi_pm_good)
111 return;
112
john stultz5d0cf412006-06-26 00:25:12 -0700113 /* the bug has been fixed in PIIX4M */
Auke Kok44c10132007-06-08 15:46:36 -0700114 if (dev->revision < 3) {
john stultz5d0cf412006-06-26 00:25:12 -0700115 printk(KERN_WARNING "* Found PM-Timer Bug on the chipset."
116 " Due to workarounds for a bug,\n"
117 "* this clock source is slow. Consider trying"
118 " other clock sources\n");
119
120 acpi_pm_need_workaround();
121 }
122}
123DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3,
124 acpi_pm_check_blacklist);
125
126static void __devinit acpi_pm_check_graylist(struct pci_dev *dev)
127{
128 if (acpi_pm_good)
129 return;
130
131 printk(KERN_WARNING "* The chipset may have PM-Timer Bug. Due to"
132 " workarounds for a bug,\n"
133 "* this clock source is slow. If you are sure your timer"
134 " does not have\n"
135 "* this bug, please use \"acpi_pm_good\" to disable the"
136 " workaround\n");
137
138 acpi_pm_need_workaround();
139}
140DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801DB_0,
141 acpi_pm_check_graylist);
Daniel Walker78f32662006-10-21 10:24:10 -0700142DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
143 acpi_pm_check_graylist);
john stultz5d0cf412006-06-26 00:25:12 -0700144#endif
145
john stultz562f9c52006-12-08 02:36:02 -0800146#ifndef CONFIG_X86_64
Ingo Molnar1164dd02009-01-28 19:34:09 +0100147#include <asm/mach_timer.h>
john stultz562f9c52006-12-08 02:36:02 -0800148#define PMTMR_EXPECTED_RATE \
149 ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
150/*
151 * Some boards have the PMTMR running way too fast. We check
152 * the PMTMR rate against PIT channel 2 to catch these cases.
153 */
154static int verify_pmtmr_rate(void)
155{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700156 cycle_t value1, value2;
john stultz562f9c52006-12-08 02:36:02 -0800157 unsigned long count, delta;
158
159 mach_prepare_counter();
Magnus Damm8e196082009-04-21 12:24:00 -0700160 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800161 mach_countup(&count);
Magnus Damm8e196082009-04-21 12:24:00 -0700162 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800163 delta = (value2 - value1) & ACPI_PM_MASK;
164
165 /* Check that the PMTMR delta is within 5% of what we expect */
166 if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
167 delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
168 printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% "
169 "of normal - aborting.\n",
170 100UL * delta / PMTMR_EXPECTED_RATE);
171 return -1;
172 }
173
174 return 0;
175}
176#else
177#define verify_pmtmr_rate() (0)
178#endif
john stultz5d0cf412006-06-26 00:25:12 -0700179
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700180/* Number of monotonicity checks to perform during initialization */
181#define ACPI_PM_MONOTONICITY_CHECKS 10
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200182/* Number of reads we try to get two different values */
183#define ACPI_PM_READ_CHECKS 10000
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700184
john stultz5d0cf412006-06-26 00:25:12 -0700185static int __init init_acpi_pm_clocksource(void)
186{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700187 cycle_t value1, value2;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200188 unsigned int i, j = 0;
john stultz5d0cf412006-06-26 00:25:12 -0700189
190 if (!pmtmr_ioport)
191 return -ENODEV;
192
193 clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
194 clocksource_acpi_pm.shift);
195
196 /* "verify" this timing source: */
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700197 for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) {
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200198 udelay(100 * j);
Magnus Damm8e196082009-04-21 12:24:00 -0700199 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200200 for (i = 0; i < ACPI_PM_READ_CHECKS; i++) {
Magnus Damm8e196082009-04-21 12:24:00 -0700201 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700202 if (value2 == value1)
203 continue;
204 if (value2 > value1)
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700205 break;
206 if ((value2 < value1) && ((value2) < 0xFFF))
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700207 break;
208 printk(KERN_INFO "PM-Timer had inconsistent results:"
209 " 0x%#llx, 0x%#llx - aborting.\n",
210 value1, value2);
211 return -EINVAL;
212 }
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200213 if (i == ACPI_PM_READ_CHECKS) {
214 printk(KERN_INFO "PM-Timer failed consistency check "
215 " (0x%#llx) - aborting.\n", value1);
216 return -ENODEV;
217 }
john stultz5d0cf412006-06-26 00:25:12 -0700218 }
john stultz5d0cf412006-06-26 00:25:12 -0700219
john stultz562f9c52006-12-08 02:36:02 -0800220 if (verify_pmtmr_rate() != 0)
221 return -ENODEV;
222
john stultza2752542006-06-26 00:25:14 -0700223 return clocksource_register(&clocksource_acpi_pm);
john stultz5d0cf412006-06-26 00:25:12 -0700224}
225
john stultz6bb74df2007-03-05 00:30:50 -0800226/* We use fs_initcall because we want the PCI fixups to have run
227 * but we still need to load before device_initcall
228 */
229fs_initcall(init_acpi_pm_clocksource);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200230
231/*
232 * Allow an override of the IOPort. Stupid BIOSes do not tell us about
233 * the PMTimer, but we might know where it is.
234 */
235static int __init parse_pmtmr(char *arg)
236{
237 unsigned long base;
238
239 if (strict_strtoul(arg, 16, &base))
240 return -EINVAL;
David Howellsee974e02008-08-20 16:37:26 -0700241#ifdef CONFIG_X86_64
242 if (base > UINT_MAX)
243 return -ERANGE;
244#endif
Linus Torvalds14351762008-07-15 11:01:39 -0700245 printk(KERN_INFO "PMTMR IOPort override: 0x%04x -> 0x%04lx\n",
David Howellsee974e02008-08-20 16:37:26 -0700246 pmtmr_ioport, base);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200247 pmtmr_ioport = base;
248
249 return 1;
250}
251__setup("pmtmr=", parse_pmtmr);