blob: 7fcb77a9d0111855948d5a02003c2845e8f5a8b3 [file] [log] [blame]
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
19#include <linux/clocksource.h>
20#include <linux/errno.h>
21#include <linux/init.h>
22#include <linux/pci.h>
23#include <asm/io.h>
24
25/* Number of PMTMR ticks expected during calibration run */
26#define PMTMR_TICKS_PER_SEC 3579545
27
28/*
29 * The I/O port the PMTMR resides at.
30 * The location is detected during setup_arch(),
31 * in arch/i386/acpi/boot.c
32 */
Andreas Mohr7d622d42006-06-26 00:25:14 -070033u32 pmtmr_ioport __read_mostly;
john stultz5d0cf412006-06-26 00:25:12 -070034
Jim Cromie7f9f3032006-06-26 00:25:15 -070035#define ACPI_PM_MASK CLOCKSOURCE_MASK(24) /* limit it to 24 bits */
john stultz5d0cf412006-06-26 00:25:12 -070036
37static inline u32 read_pmtmr(void)
38{
39 /* mask the output to 24 bits */
40 return inl(pmtmr_ioport) & ACPI_PM_MASK;
41}
42
43static cycle_t acpi_pm_read_verified(void)
44{
45 u32 v1 = 0, v2 = 0, v3 = 0;
46
47 /*
48 * It has been reported that because of various broken
49 * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM clock
Andreas Mohr7d622d42006-06-26 00:25:14 -070050 * source is not latched, you must read it multiple
john stultz5d0cf412006-06-26 00:25:12 -070051 * times to ensure a safe value is read:
52 */
53 do {
54 v1 = read_pmtmr();
55 v2 = read_pmtmr();
56 v3 = read_pmtmr();
Daniel Walker78f32662006-10-21 10:24:10 -070057 } while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
58 || (v3 > v1 && v3 < v2)));
john stultz5d0cf412006-06-26 00:25:12 -070059
60 return (cycle_t)v2;
61}
62
63static cycle_t acpi_pm_read(void)
64{
65 return (cycle_t)read_pmtmr();
66}
67
68static struct clocksource clocksource_acpi_pm = {
69 .name = "acpi_pm",
70 .rating = 200,
71 .read = acpi_pm_read,
72 .mask = (cycle_t)ACPI_PM_MASK,
73 .mult = 0, /*to be caluclated*/
74 .shift = 22,
75 .is_continuous = 1,
76};
77
78
79#ifdef CONFIG_PCI
80static int acpi_pm_good;
81static int __init acpi_pm_good_setup(char *__str)
82{
83 acpi_pm_good = 1;
84 return 1;
85}
86__setup("acpi_pm_good", acpi_pm_good_setup);
87
88static inline void acpi_pm_need_workaround(void)
89{
90 clocksource_acpi_pm.read = acpi_pm_read_verified;
91 clocksource_acpi_pm.rating = 110;
92}
93
94/*
95 * PIIX4 Errata:
96 *
97 * The power management timer may return improper results when read.
98 * Although the timer value settles properly after incrementing,
99 * while incrementing there is a 3 ns window every 69.8 ns where the
100 * timer value is indeterminate (a 4.2% chance that the data will be
101 * incorrect when read). As a result, the ACPI free running count up
102 * timer specification is violated due to erroneous reads.
103 */
104static void __devinit acpi_pm_check_blacklist(struct pci_dev *dev)
105{
106 u8 rev;
107
108 if (acpi_pm_good)
109 return;
110
111 pci_read_config_byte(dev, PCI_REVISION_ID, &rev);
112 /* the bug has been fixed in PIIX4M */
113 if (rev < 3) {
114 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
145
146static int __init init_acpi_pm_clocksource(void)
147{
148 u32 value1, value2;
149 unsigned int i;
150
151 if (!pmtmr_ioport)
152 return -ENODEV;
153
154 clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
155 clocksource_acpi_pm.shift);
156
157 /* "verify" this timing source: */
158 value1 = read_pmtmr();
159 for (i = 0; i < 10000; i++) {
160 value2 = read_pmtmr();
161 if (value2 == value1)
162 continue;
163 if (value2 > value1)
164 goto pm_good;
165 if ((value2 < value1) && ((value2) < 0xFFF))
166 goto pm_good;
167 printk(KERN_INFO "PM-Timer had inconsistent results:"
168 " 0x%#x, 0x%#x - aborting.\n", value1, value2);
169 return -EINVAL;
170 }
171 printk(KERN_INFO "PM-Timer had no reasonable result:"
172 " 0x%#x - aborting.\n", value1);
173 return -ENODEV;
174
175pm_good:
john stultza2752542006-06-26 00:25:14 -0700176 return clocksource_register(&clocksource_acpi_pm);
john stultz5d0cf412006-06-26 00:25:12 -0700177}
178
179module_init(init_acpi_pm_clocksource);