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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) | |
7edcb9ab OR |
8 | * Intel 82801DB (ICH4) (HW PEC supported) |
9 | * Intel 82801EB/ER (ICH5) (HW PEC supported) | |
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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) | |
d28dc711 | 15 | * Intel 82801I (ICH9) |
c429a247 SH |
16 | * Intel EP80579 (Tolapai) |
17 | * Intel 82801JI (ICH10) | |
18 | * Intel PCH | |
e07bc679 | 19 | Datasheets: Publicly available at the Intel website |
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20 | |
21 | Authors: | |
1da177e4 | 22 | Mark Studebaker <mdsxyz123@yahoo.com> |
6342064c | 23 | Jean Delvare <khali@linux-fr.org> |
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24 | |
25 | ||
26 | Module Parameters | |
27 | ----------------- | |
28 | ||
d8db8f98 | 29 | None. |
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30 | |
31 | ||
32 | Description | |
33 | ----------- | |
34 | ||
35 | The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), | |
c429a247 | 36 | ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of |
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37 | Intel's '810' chipset for Celeron-based PCs, '810E' chipset for |
38 | Pentium-based PCs, '815E' chipset, and others. | |
39 | ||
40 | The ICH chips contain at least SEVEN separate PCI functions in TWO logical | |
41 | PCI devices. An output of lspci will show something similar to the | |
42 | following: | |
43 | ||
44 | 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) | |
45 | 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) | |
46 | 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) | |
47 | 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) | |
48 | 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) | |
49 | ||
50 | The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial | |
51 | Controller. | |
52 | ||
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53 | The ICH chips are quite similar to Intel's PIIX4 chip, at least in the |
54 | SMBus controller. | |
55 | ||
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56 | |
57 | Process Call Support | |
58 | -------------------- | |
59 | ||
60 | Not supported. | |
61 | ||
62 | ||
63 | I2C Block Read Support | |
64 | ---------------------- | |
65 | ||
6342064c | 66 | I2C block read is supported on the 82801EB (ICH5) and later chips. |
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67 | |
68 | ||
69 | SMBus 2.0 Support | |
70 | ----------------- | |
71 | ||
72 | The 82801DB (ICH4) and later chips support several SMBus 2.0 features. | |
73 | ||
099ab118 JD |
74 | |
75 | Hidden ICH SMBus | |
76 | ---------------- | |
77 | ||
78 | If your system has an Intel ICH south bridge, but you do NOT see the | |
79 | SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the | |
80 | BIOS to enable it, it means it has been hidden by the BIOS code. Asus is | |
81 | well known for first doing this on their P4B motherboard, and many other | |
82 | boards after that. Some vendor machines are affected as well. | |
83 | ||
84 | The first thing to try is the "i2c_ec" ACPI driver. It could be that the | |
85 | SMBus was hidden on purpose because it'll be driven by ACPI. If the | |
86 | i2c_ec driver works for you, just forget about the i2c-i801 driver and | |
87 | don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you | |
88 | better make sure that the SMBus isn't used by the ACPI code. Try loading | |
89 | the "fan" and "thermal" drivers, and check in /proc/acpi/fan and | |
90 | /proc/acpi/thermal_zone. If you find anything there, it's likely that | |
91 | the ACPI is accessing the SMBus and it's safer not to unhide it. Only | |
92 | once you are certain that ACPI isn't using the SMBus, you can attempt | |
93 | to unhide it. | |
94 | ||
95 | In order to unhide the SMBus, we need to change the value of a PCI | |
96 | register before the kernel enumerates the PCI devices. This is done in | |
97 | drivers/pci/quirks.c, where all affected boards must be listed (see | |
98 | function asus_hides_smbus_hostbridge.) If the SMBus device is missing, | |
99 | and you think there's something interesting on the SMBus (e.g. a | |
100 | hardware monitoring chip), you need to add your board to the list. | |
101 | ||
102 | The motherboard is identified using the subvendor and subdevice IDs of the | |
103 | host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": | |
104 | ||
105 | 00:00.0 Class 0600: 8086:2570 (rev 02) | |
106 | Subsystem: 1043:80f2 | |
107 | Flags: bus master, fast devsel, latency 0 | |
108 | Memory at fc000000 (32-bit, prefetchable) [size=32M] | |
109 | Capabilities: [e4] #09 [2106] | |
110 | Capabilities: [a0] AGP version 3.0 | |
111 | ||
112 | Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 | |
113 | (Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic | |
114 | names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, | |
115 | and then add a case for your subdevice ID at the right place in | |
116 | drivers/pci/quirks.c. Then please give it very good testing, to make sure | |
117 | that the unhidden SMBus doesn't conflict with e.g. ACPI. | |
118 | ||
119 | If it works, proves useful (i.e. there are usable chips on the SMBus) | |
120 | and seems safe, please submit a patch for inclusion into the kernel. | |
121 | ||
122 | Note: There's a useful script in lm_sensors 2.10.2 and later, named | |
123 | unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to | |
124 | temporarily unhide the SMBus without having to patch and recompile your | |
125 | kernel. It's very convenient if you just want to check if there's | |
126 | anything interesting on your hidden ICH SMBus. | |
127 | ||
128 | ||
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129 | ********************** |
130 | The lm_sensors project gratefully acknowledges the support of Texas | |
131 | Instruments in the initial development of this driver. | |
132 | ||
133 | The lm_sensors project gratefully acknowledges the support of Intel in the | |
134 | development of SMBus 2.0 / ICH4 features of this driver. |