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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,
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
Daniel Walkerf5f1a242006-12-10 02:21:33 -080076static int __devinitdata 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
Magnus Damm8e196082009-04-21 12:24:00 -070084static cycle_t acpi_pm_read_slow(struct clocksource *cs)
Bjorn Helgaas0a57b782008-12-01 14:18:12 -080085{
86 return (cycle_t)acpi_pm_read_verified();
87}
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 */
105static void __devinit acpi_pm_check_blacklist(struct pci_dev *dev)
106{
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) {
john stultz5d0cf412006-06-26 00:25:12 -0700112 printk(KERN_WARNING "* Found PM-Timer Bug on the chipset."
113 " Due to workarounds for a bug,\n"
114 "* this clock source is slow. Consider trying"
115 " other clock sources\n");
116
117 acpi_pm_need_workaround();
118 }
119}
120DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3,
121 acpi_pm_check_blacklist);
122
123static void __devinit acpi_pm_check_graylist(struct pci_dev *dev)
124{
125 if (acpi_pm_good)
126 return;
127
128 printk(KERN_WARNING "* The chipset may have PM-Timer Bug. Due to"
129 " workarounds for a bug,\n"
130 "* this clock source is slow. If you are sure your timer"
131 " does not have\n"
132 "* this bug, please use \"acpi_pm_good\" to disable the"
133 " workaround\n");
134
135 acpi_pm_need_workaround();
136}
137DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801DB_0,
138 acpi_pm_check_graylist);
Daniel Walker78f32662006-10-21 10:24:10 -0700139DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
140 acpi_pm_check_graylist);
john stultz5d0cf412006-06-26 00:25:12 -0700141#endif
142
john stultz562f9c52006-12-08 02:36:02 -0800143#ifndef CONFIG_X86_64
Ingo Molnar1164dd02009-01-28 19:34:09 +0100144#include <asm/mach_timer.h>
john stultz562f9c52006-12-08 02:36:02 -0800145#define PMTMR_EXPECTED_RATE \
Deepak Saxenacbf15992011-11-01 14:25:01 -0700146 ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (PIT_TICK_RATE>>10))
john stultz562f9c52006-12-08 02:36:02 -0800147/*
148 * Some boards have the PMTMR running way too fast. We check
149 * the PMTMR rate against PIT channel 2 to catch these cases.
150 */
151static int verify_pmtmr_rate(void)
152{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700153 cycle_t value1, value2;
john stultz562f9c52006-12-08 02:36:02 -0800154 unsigned long count, delta;
155
156 mach_prepare_counter();
Magnus Damm8e196082009-04-21 12:24:00 -0700157 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800158 mach_countup(&count);
Magnus Damm8e196082009-04-21 12:24:00 -0700159 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
john stultz562f9c52006-12-08 02:36:02 -0800160 delta = (value2 - value1) & ACPI_PM_MASK;
161
162 /* Check that the PMTMR delta is within 5% of what we expect */
163 if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
164 delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
165 printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% "
166 "of normal - aborting.\n",
167 100UL * delta / PMTMR_EXPECTED_RATE);
168 return -1;
169 }
170
171 return 0;
172}
173#else
174#define verify_pmtmr_rate() (0)
175#endif
john stultz5d0cf412006-06-26 00:25:12 -0700176
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700177/* Number of monotonicity checks to perform during initialization */
178#define ACPI_PM_MONOTONICITY_CHECKS 10
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200179/* Number of reads we try to get two different values */
180#define ACPI_PM_READ_CHECKS 10000
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700181
john stultz5d0cf412006-06-26 00:25:12 -0700182static int __init init_acpi_pm_clocksource(void)
183{
Dominik Brodowskidfdf7482008-09-05 14:05:33 -0700184 cycle_t value1, value2;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200185 unsigned int i, j = 0;
john stultz5d0cf412006-06-26 00:25:12 -0700186
187 if (!pmtmr_ioport)
188 return -ENODEV;
189
john stultz5d0cf412006-06-26 00:25:12 -0700190 /* "verify" this timing source: */
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700191 for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) {
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200192 udelay(100 * j);
Magnus Damm8e196082009-04-21 12:24:00 -0700193 value1 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200194 for (i = 0; i < ACPI_PM_READ_CHECKS; i++) {
Magnus Damm8e196082009-04-21 12:24:00 -0700195 value2 = clocksource_acpi_pm.read(&clocksource_acpi_pm);
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700196 if (value2 == value1)
197 continue;
198 if (value2 > value1)
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700199 break;
200 if ((value2 < value1) && ((value2) < 0xFFF))
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700201 break;
202 printk(KERN_INFO "PM-Timer had inconsistent results:"
203 " 0x%#llx, 0x%#llx - aborting.\n",
204 value1, value2);
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800205 pmtmr_ioport = 0;
Dominik Brodowski4ab6a212008-09-05 14:05:35 -0700206 return -EINVAL;
207 }
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200208 if (i == ACPI_PM_READ_CHECKS) {
209 printk(KERN_INFO "PM-Timer failed consistency check "
210 " (0x%#llx) - aborting.\n", value1);
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800211 pmtmr_ioport = 0;
Dominik Brodowskif1926ce2008-09-11 11:09:49 +0200212 return -ENODEV;
213 }
john stultz5d0cf412006-06-26 00:25:12 -0700214 }
john stultz5d0cf412006-06-26 00:25:12 -0700215
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800216 if (verify_pmtmr_rate() != 0){
217 pmtmr_ioport = 0;
john stultz562f9c52006-12-08 02:36:02 -0800218 return -ENODEV;
Konrad Rzeszutek Wilkdb6b1752011-01-14 09:47:26 -0800219 }
john stultz562f9c52006-12-08 02:36:02 -0800220
John Stultzf12a15b2010-07-13 17:56:27 -0700221 return clocksource_register_hz(&clocksource_acpi_pm,
222 PMTMR_TICKS_PER_SEC);
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;
David Howellsee974e02008-08-20 16:37:26 -0700240#ifdef CONFIG_X86_64
241 if (base > UINT_MAX)
242 return -ERANGE;
243#endif
Linus Torvalds14351762008-07-15 11:01:39 -0700244 printk(KERN_INFO "PMTMR IOPort override: 0x%04x -> 0x%04lx\n",
David Howellsee974e02008-08-20 16:37:26 -0700245 pmtmr_ioport, base);
Thomas Gleixner6b148502008-05-21 21:14:58 +0200246 pmtmr_ioport = base;
247
248 return 1;
249}
250__setup("pmtmr=", parse_pmtmr);