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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
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +010061static u64 acpi_pm_read(struct clocksource *cs)
john stultz5d0cf412006-06-26 00:25:12 -070062{
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +010063 return (u64)read_pmtmr();
john stultz5d0cf412006-06-26 00:25:12 -070064}
65
66static struct clocksource clocksource_acpi_pm = {
67 .name = "acpi_pm",
68 .rating = 200,
69 .read = acpi_pm_read,
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +010070 .mask = (u64)ACPI_PM_MASK,
Thomas Gleixner73b08d22007-02-16 01:27:36 -080071 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
john stultz5d0cf412006-06-26 00:25:12 -070072};
73
74
75#ifdef CONFIG_PCI
Greg Kroah-Hartman18505142012-12-21 15:11:38 -080076static int acpi_pm_good;
john stultz5d0cf412006-06-26 00:25:12 -070077static int __init acpi_pm_good_setup(char *__str)
78{
Daniel Walkerf5f1a242006-12-10 02:21:33 -080079 acpi_pm_good = 1;
80 return 1;
john stultz5d0cf412006-06-26 00:25:12 -070081}
82__setup("acpi_pm_good", acpi_pm_good_setup);
83
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +010084static u64 acpi_pm_read_slow(struct clocksource *cs)
Bjorn Helgaas0a57b782008-12-01 14:18:12 -080085{
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +010086 return (u64)acpi_pm_read_verified();
Bjorn Helgaas0a57b782008-12-01 14:18:12 -080087}
88
john stultz5d0cf412006-06-26 00:25:12 -070089static inline void acpi_pm_need_workaround(void)
90{
Thomas Gleixnerd66bea52007-02-16 01:27:57 -080091 clocksource_acpi_pm.read = acpi_pm_read_slow;
john stultz1ff100d2007-03-26 21:32:19 -080092 clocksource_acpi_pm.rating = 120;
john stultz5d0cf412006-06-26 00:25:12 -070093}
94
95/*
96 * PIIX4 Errata:
97 *
98 * The power management timer may return improper results when read.
99 * Although the timer value settles properly after incrementing,
100 * while incrementing there is a 3 ns window every 69.8 ns where the
101 * timer value is indeterminate (a 4.2% chance that the data will be
102 * incorrect when read). As a result, the ACPI free running count up
103 * timer specification is violated due to erroneous reads.
104 */
Greg Kroah-Hartman18505142012-12-21 15:11:38 -0800105static void acpi_pm_check_blacklist(struct pci_dev *dev)
john stultz5d0cf412006-06-26 00:25:12 -0700106{
john stultz5d0cf412006-06-26 00:25:12 -0700107 if (acpi_pm_good)
108 return;
109
john stultz5d0cf412006-06-26 00:25:12 -0700110 /* the bug has been fixed in PIIX4M */
Auke Kok44c10132007-06-08 15:46:36 -0700111 if (dev->revision < 3) {
Andy Shevchenko01414882015-12-28 15:41:25 +0200112 pr_warn("* Found PM-Timer Bug on the chipset. Due to workarounds for a bug,\n"
113 "* this clock source is slow. Consider trying other clock sources\n");
john stultz5d0cf412006-06-26 00:25:12 -0700114
115 acpi_pm_need_workaround();
116 }
117}
118DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3,
119 acpi_pm_check_blacklist);
120
Greg Kroah-Hartman18505142012-12-21 15:11:38 -0800121static void acpi_pm_check_graylist(struct pci_dev *dev)
john stultz5d0cf412006-06-26 00:25:12 -0700122{
123 if (acpi_pm_good)
124 return;
125
Andy Shevchenko01414882015-12-28 15:41:25 +0200126 pr_warn("* The chipset may have PM-Timer Bug. Due to workarounds for a bug,\n"
127 "* this clock source is slow. If you are sure your timer does not have\n"
128 "* this bug, please use \"acpi_pm_good\" to disable the workaround\n");
john stultz5d0cf412006-06-26 00:25:12 -0700129
130 acpi_pm_need_workaround();
131}
132DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801DB_0,
133 acpi_pm_check_graylist);
Daniel Walker78f32662006-10-21 10:24:10 -0700134DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
135 acpi_pm_check_graylist);
john stultz5d0cf412006-06-26 00:25:12 -0700136#endif
137
john stultz562f9c52006-12-08 02:36:02 -0800138#ifndef CONFIG_X86_64
Ingo Molnar1164dd02009-01-28 19:34:09 +0100139#include <asm/mach_timer.h>
john stultz562f9c52006-12-08 02:36:02 -0800140#define PMTMR_EXPECTED_RATE \
Deepak Saxenacbf15992011-11-01 14:25:01 -0700141 ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (PIT_TICK_RATE>>10))
john stultz562f9c52006-12-08 02:36:02 -0800142/*
143 * Some boards have the PMTMR running way too fast. We check
144 * the PMTMR rate against PIT channel 2 to catch these cases.
145 */
146static int verify_pmtmr_rate(void)
147{
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +0100148 u64 value1, value2;
john stultz562f9c52006-12-08 02:36:02 -0800149 unsigned long count, delta;
150
151 mach_prepare_counter();
Magnus Damm8e196082009-04-21 12:24:00 -0700152 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800153 mach_countup(&count);
Magnus Damm8e196082009-04-21 12:24:00 -0700154 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800155 delta = (value2 - value1) & ACPI_PM_MASK;
156
157 /* Check that the PMTMR delta is within 5% of what we expect */
158 if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
159 delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
Andy Shevchenko01414882015-12-28 15:41:25 +0200160 pr_info("PM-Timer running at invalid rate: %lu%% of normal - aborting.\n",
john stultz562f9c52006-12-08 02:36:02 -0800161 100UL * delta / PMTMR_EXPECTED_RATE);
162 return -1;
163 }
164
165 return 0;
166}
167#else
168#define verify_pmtmr_rate() (0)
169#endif
john stultz5d0cf412006-06-26 00:25:12 -0700170
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700171/* Number of monotonicity checks to perform during initialization */
172#define ACPI_PM_MONOTONICITY_CHECKS 10
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200173/* Number of reads we try to get two different values */
174#define ACPI_PM_READ_CHECKS 10000
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700175
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200176static int __init init_acpi_pm_clocksource(void)
john stultz5d0cf412006-06-26 00:25:12 -0700177{
Thomas Gleixnera5a1d1c2016-12-21 20:32:01 +0100178 u64 value1, value2;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200179 unsigned int i, j = 0;
john stultz5d0cf412006-06-26 00:25:12 -0700180
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200181 if (!pmtmr_ioport)
182 return -ENODEV;
john stultz5d0cf412006-06-26 00:25:12 -0700183
john stultz5d0cf412006-06-26 00:25:12 -0700184 /* "verify" this timing source: */
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700185 for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) {
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200186 udelay(100 * j);
Magnus Damm8e196082009-04-21 12:24:00 -0700187 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200188 for (i = 0; i < ACPI_PM_READ_CHECKS; i++) {
Magnus Damm8e196082009-04-21 12:24:00 -0700189 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700190 if (value2 == value1)
191 continue;
192 if (value2 > value1)
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700193 break;
194 if ((value2 < value1) && ((value2) < 0xFFF))
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700195 break;
Andy Shevchenko01414882015-12-28 15:41:25 +0200196 pr_info("PM-Timer had inconsistent results: %#llx, %#llx - aborting.\n",
197 value1, value2);
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800198 pmtmr_ioport = 0;
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200199 return -EINVAL;
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700200 }
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200201 if (i == ACPI_PM_READ_CHECKS) {
Andy Shevchenko01414882015-12-28 15:41:25 +0200202 pr_info("PM-Timer failed consistency check (%#llx) - aborting.\n",
203 value1);
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800204 pmtmr_ioport = 0;
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200205 return -ENODEV;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200206 }
john stultz5d0cf412006-06-26 00:25:12 -0700207 }
john stultz5d0cf412006-06-26 00:25:12 -0700208
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800209 if (verify_pmtmr_rate() != 0){
210 pmtmr_ioport = 0;
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200211 return -ENODEV;
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800212 }
john stultz562f9c52006-12-08 02:36:02 -0800213
Thomas Gleixnerd48fc632012-04-11 23:49:16 +0200214 return clocksource_register_hz(&clocksource_acpi_pm,
John Stultzf12a15b2010-07-13 17:56:27 -0700215 PMTMR_TICKS_PER_SEC);
john stultz5d0cf412006-06-26 00:25:12 -0700216}
217
john stultz6bb74df2007-03-05 00:30:50 -0800218/* We use fs_initcall because we want the PCI fixups to have run
219 * but we still need to load before device_initcall
220 */
221fs_initcall(init_acpi_pm_clocksource);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200222
223/*
224 * Allow an override of the IOPort. Stupid BIOSes do not tell us about
225 * the PMTimer, but we might know where it is.
226 */
227static int __init parse_pmtmr(char *arg)
228{
Dan Carpenter60e3bf12012-10-20 07:46:02 +0300229 unsigned int base;
230 int ret;
Thomas Gleixner6b148502008-05-21 21:14:58 +0200231
Dan Carpenter60e3bf12012-10-20 07:46:02 +0300232 ret = kstrtouint(arg, 16, &base);
233 if (ret)
234 return ret;
235
236 pr_info("PMTMR IOPort override: 0x%04x -> 0x%04x\n", pmtmr_ioport,
237 base);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200238 pmtmr_ioport = base;
239
240 return 1;
241}
242__setup("pmtmr=", parse_pmtmr);