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1 | Kernel driver i2c-i801 |
2 | ||
3 | Supported adapters: | |
4 | * Intel 82801AA and 82801AB (ICH and ICH0 - part of the | |
5 | '810' and '810E' chipsets) | |
6 | * Intel 82801BA (ICH2 - part of the '815E' chipset) | |
7 | * Intel 82801CA/CAM (ICH3) | |
8 | * Intel 82801DB (ICH4) (HW PEC supported, 32 byte buffer not supported) | |
9 | * Intel 82801EB/ER (ICH5) (HW PEC supported, 32 byte buffer not supported) | |
10 | * Intel 6300ESB | |
11 | * Intel 82801FB/FR/FW/FRW (ICH6) | |
a980a99a JG |
12 | * Intel 82801G (ICH7) |
13 | * Intel 631xESB/632xESB (ESB2) | |
14 | * Intel 82801H (ICH8) | |
15 | * Intel ICH9 | |
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16 | Datasheets: Publicly available at the Intel website |
17 | ||
18 | Authors: | |
19 | Frodo Looijaard <frodol@dds.nl>, | |
20 | Philip Edelbrock <phil@netroedge.com>, | |
21 | Mark Studebaker <mdsxyz123@yahoo.com> | |
22 | ||
23 | ||
24 | Module Parameters | |
25 | ----------------- | |
26 | ||
d8db8f98 | 27 | None. |
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28 | |
29 | ||
30 | Description | |
31 | ----------- | |
32 | ||
33 | The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), | |
34 | ICH3 (82801CA/CAM) and later devices are Intel chips that are a part of | |
35 | Intel's '810' chipset for Celeron-based PCs, '810E' chipset for | |
36 | Pentium-based PCs, '815E' chipset, and others. | |
37 | ||
38 | The ICH chips contain at least SEVEN separate PCI functions in TWO logical | |
39 | PCI devices. An output of lspci will show something similar to the | |
40 | following: | |
41 | ||
42 | 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) | |
43 | 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) | |
44 | 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) | |
45 | 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) | |
46 | 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) | |
47 | ||
48 | The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial | |
49 | Controller. | |
50 | ||
1da177e4 LT |
51 | The ICH chips are quite similar to Intel's PIIX4 chip, at least in the |
52 | SMBus controller. | |
53 | ||
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54 | |
55 | Process Call Support | |
56 | -------------------- | |
57 | ||
58 | Not supported. | |
59 | ||
60 | ||
61 | I2C Block Read Support | |
62 | ---------------------- | |
63 | ||
64 | Not supported at the moment. | |
65 | ||
66 | ||
67 | SMBus 2.0 Support | |
68 | ----------------- | |
69 | ||
70 | The 82801DB (ICH4) and later chips support several SMBus 2.0 features. | |
71 | ||
099ab118 JD |
72 | |
73 | Hidden ICH SMBus | |
74 | ---------------- | |
75 | ||
76 | If your system has an Intel ICH south bridge, but you do NOT see the | |
77 | SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the | |
78 | BIOS to enable it, it means it has been hidden by the BIOS code. Asus is | |
79 | well known for first doing this on their P4B motherboard, and many other | |
80 | boards after that. Some vendor machines are affected as well. | |
81 | ||
82 | The first thing to try is the "i2c_ec" ACPI driver. It could be that the | |
83 | SMBus was hidden on purpose because it'll be driven by ACPI. If the | |
84 | i2c_ec driver works for you, just forget about the i2c-i801 driver and | |
85 | don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you | |
86 | better make sure that the SMBus isn't used by the ACPI code. Try loading | |
87 | the "fan" and "thermal" drivers, and check in /proc/acpi/fan and | |
88 | /proc/acpi/thermal_zone. If you find anything there, it's likely that | |
89 | the ACPI is accessing the SMBus and it's safer not to unhide it. Only | |
90 | once you are certain that ACPI isn't using the SMBus, you can attempt | |
91 | to unhide it. | |
92 | ||
93 | In order to unhide the SMBus, we need to change the value of a PCI | |
94 | register before the kernel enumerates the PCI devices. This is done in | |
95 | drivers/pci/quirks.c, where all affected boards must be listed (see | |
96 | function asus_hides_smbus_hostbridge.) If the SMBus device is missing, | |
97 | and you think there's something interesting on the SMBus (e.g. a | |
98 | hardware monitoring chip), you need to add your board to the list. | |
99 | ||
100 | The motherboard is identified using the subvendor and subdevice IDs of the | |
101 | host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": | |
102 | ||
103 | 00:00.0 Class 0600: 8086:2570 (rev 02) | |
104 | Subsystem: 1043:80f2 | |
105 | Flags: bus master, fast devsel, latency 0 | |
106 | Memory at fc000000 (32-bit, prefetchable) [size=32M] | |
107 | Capabilities: [e4] #09 [2106] | |
108 | Capabilities: [a0] AGP version 3.0 | |
109 | ||
110 | Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 | |
111 | (Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic | |
112 | names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, | |
113 | and then add a case for your subdevice ID at the right place in | |
114 | drivers/pci/quirks.c. Then please give it very good testing, to make sure | |
115 | that the unhidden SMBus doesn't conflict with e.g. ACPI. | |
116 | ||
117 | If it works, proves useful (i.e. there are usable chips on the SMBus) | |
118 | and seems safe, please submit a patch for inclusion into the kernel. | |
119 | ||
120 | Note: There's a useful script in lm_sensors 2.10.2 and later, named | |
121 | unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to | |
122 | temporarily unhide the SMBus without having to patch and recompile your | |
123 | kernel. It's very convenient if you just want to check if there's | |
124 | anything interesting on your hidden ICH SMBus. | |
125 | ||
126 | ||
1da177e4 LT |
127 | ********************** |
128 | The lm_sensors project gratefully acknowledges the support of Texas | |
129 | Instruments in the initial development of this driver. | |
130 | ||
131 | The lm_sensors project gratefully acknowledges the support of Intel in the | |
132 | development of SMBus 2.0 / ICH4 features of this driver. |