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Commit | Line | Data |
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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) | |
9 | * Intel 82801EB/ER (ICH5) (HW PEC supported) | |
10 | * Intel 6300ESB | |
11 | * Intel 82801FB/FR/FW/FRW (ICH6) | |
12 | * Intel 82801G (ICH7) | |
13 | * Intel 631xESB/632xESB (ESB2) | |
14 | * Intel 82801H (ICH8) | |
15 | * Intel 82801I (ICH9) | |
16 | * Intel EP80579 (Tolapai) | |
17 | * Intel 82801JI (ICH10) | |
18 | * Intel 5/3400 Series (PCH) | |
19 | * Intel Cougar Point (PCH) | |
20 | * Intel Patsburg (PCH) | |
21 | Datasheets: Publicly available at the Intel website | |
22 | ||
23 | On Intel Patsburg and later chipsets, both the normal host SMBus controller | |
24 | and the additional 'Integrated Device Function' controllers are supported. | |
25 | ||
26 | Authors: | |
27 | Mark Studebaker <mdsxyz123@yahoo.com> | |
28 | Jean Delvare <khali@linux-fr.org> | |
29 | ||
30 | ||
31 | Module Parameters | |
32 | ----------------- | |
33 | ||
34 | * disable_features (bit vector) | |
35 | Disable selected features normally supported by the device. This makes it | |
36 | possible to work around possible driver or hardware bugs if the feature in | |
37 | question doesn't work as intended for whatever reason. Bit values: | |
38 | 1 disable SMBus PEC | |
39 | 2 disable the block buffer | |
40 | 8 disable the I2C block read functionality | |
41 | ||
42 | ||
43 | Description | |
44 | ----------- | |
45 | ||
46 | The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), | |
47 | ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of | |
48 | Intel's '810' chipset for Celeron-based PCs, '810E' chipset for | |
49 | Pentium-based PCs, '815E' chipset, and others. | |
50 | ||
51 | The ICH chips contain at least SEVEN separate PCI functions in TWO logical | |
52 | PCI devices. An output of lspci will show something similar to the | |
53 | following: | |
54 | ||
55 | 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) | |
56 | 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) | |
57 | 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) | |
58 | 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) | |
59 | 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) | |
60 | ||
61 | The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial | |
62 | Controller. | |
63 | ||
64 | The ICH chips are quite similar to Intel's PIIX4 chip, at least in the | |
65 | SMBus controller. | |
66 | ||
67 | ||
68 | Process Call Support | |
69 | -------------------- | |
70 | ||
71 | Not supported. | |
72 | ||
73 | ||
74 | I2C Block Read Support | |
75 | ---------------------- | |
76 | ||
77 | I2C block read is supported on the 82801EB (ICH5) and later chips. | |
78 | ||
79 | ||
80 | SMBus 2.0 Support | |
81 | ----------------- | |
82 | ||
83 | The 82801DB (ICH4) and later chips support several SMBus 2.0 features. | |
84 | ||
85 | ||
86 | Hidden ICH SMBus | |
87 | ---------------- | |
88 | ||
89 | If your system has an Intel ICH south bridge, but you do NOT see the | |
90 | SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the | |
91 | BIOS to enable it, it means it has been hidden by the BIOS code. Asus is | |
92 | well known for first doing this on their P4B motherboard, and many other | |
93 | boards after that. Some vendor machines are affected as well. | |
94 | ||
95 | The first thing to try is the "i2c_ec" ACPI driver. It could be that the | |
96 | SMBus was hidden on purpose because it'll be driven by ACPI. If the | |
97 | i2c_ec driver works for you, just forget about the i2c-i801 driver and | |
98 | don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you | |
99 | better make sure that the SMBus isn't used by the ACPI code. Try loading | |
100 | the "fan" and "thermal" drivers, and check in /proc/acpi/fan and | |
101 | /proc/acpi/thermal_zone. If you find anything there, it's likely that | |
102 | the ACPI is accessing the SMBus and it's safer not to unhide it. Only | |
103 | once you are certain that ACPI isn't using the SMBus, you can attempt | |
104 | to unhide it. | |
105 | ||
106 | In order to unhide the SMBus, we need to change the value of a PCI | |
107 | register before the kernel enumerates the PCI devices. This is done in | |
108 | drivers/pci/quirks.c, where all affected boards must be listed (see | |
109 | function asus_hides_smbus_hostbridge.) If the SMBus device is missing, | |
110 | and you think there's something interesting on the SMBus (e.g. a | |
111 | hardware monitoring chip), you need to add your board to the list. | |
112 | ||
113 | The motherboard is identified using the subvendor and subdevice IDs of the | |
114 | host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": | |
115 | ||
116 | 00:00.0 Class 0600: 8086:2570 (rev 02) | |
117 | Subsystem: 1043:80f2 | |
118 | Flags: bus master, fast devsel, latency 0 | |
119 | Memory at fc000000 (32-bit, prefetchable) [size=32M] | |
120 | Capabilities: [e4] #09 [2106] | |
121 | Capabilities: [a0] AGP version 3.0 | |
122 | ||
123 | Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 | |
124 | (Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic | |
125 | names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, | |
126 | and then add a case for your subdevice ID at the right place in | |
127 | drivers/pci/quirks.c. Then please give it very good testing, to make sure | |
128 | that the unhidden SMBus doesn't conflict with e.g. ACPI. | |
129 | ||
130 | If it works, proves useful (i.e. there are usable chips on the SMBus) | |
131 | and seems safe, please submit a patch for inclusion into the kernel. | |
132 | ||
133 | Note: There's a useful script in lm_sensors 2.10.2 and later, named | |
134 | unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to | |
135 | temporarily unhide the SMBus without having to patch and recompile your | |
136 | kernel. It's very convenient if you just want to check if there's | |
137 | anything interesting on your hidden ICH SMBus. | |
138 | ||
139 | ||
140 | ********************** | |
141 | The lm_sensors project gratefully acknowledges the support of Texas | |
142 | Instruments in the initial development of this driver. | |
143 | ||
144 | The lm_sensors project gratefully acknowledges the support of Intel in the | |
145 | development of SMBus 2.0 / ICH4 features of this driver. |