Root/
1 | Kernel driver it87 |
2 | ================== |
3 | |
4 | Supported chips: |
5 | * IT8705F |
6 | Prefix: 'it87' |
7 | Addresses scanned: from Super I/O config space (8 I/O ports) |
8 | Datasheet: Once publicly available at the ITE website, but no longer |
9 | * IT8712F |
10 | Prefix: 'it8712' |
11 | Addresses scanned: from Super I/O config space (8 I/O ports) |
12 | Datasheet: Once publicly available at the ITE website, but no longer |
13 | * IT8716F/IT8726F |
14 | Prefix: 'it8716' |
15 | Addresses scanned: from Super I/O config space (8 I/O ports) |
16 | Datasheet: Once publicly available at the ITE website, but no longer |
17 | * IT8718F |
18 | Prefix: 'it8718' |
19 | Addresses scanned: from Super I/O config space (8 I/O ports) |
20 | Datasheet: Once publicly available at the ITE website, but no longer |
21 | * IT8720F |
22 | Prefix: 'it8720' |
23 | Addresses scanned: from Super I/O config space (8 I/O ports) |
24 | Datasheet: Not publicly available |
25 | * IT8721F/IT8758E |
26 | Prefix: 'it8721' |
27 | Addresses scanned: from Super I/O config space (8 I/O ports) |
28 | Datasheet: Not publicly available |
29 | * SiS950 [clone of IT8705F] |
30 | Prefix: 'it87' |
31 | Addresses scanned: from Super I/O config space (8 I/O ports) |
32 | Datasheet: No longer be available |
33 | |
34 | Authors: |
35 | Christophe Gauthron |
36 | Jean Delvare <khali@linux-fr.org> |
37 | |
38 | |
39 | Module Parameters |
40 | ----------------- |
41 | |
42 | * update_vbat: int |
43 | |
44 | 0 if vbat should report power on value, 1 if vbat should be updated after |
45 | each read. Default is 0. On some boards the battery voltage is provided |
46 | by either the battery or the onboard power supply. Only the first reading |
47 | at power on will be the actual battery voltage (which the chip does |
48 | automatically). On other boards the battery voltage is always fed to |
49 | the chip so can be read at any time. Excessive reading may decrease |
50 | battery life but no information is given in the datasheet. |
51 | |
52 | * fix_pwm_polarity int |
53 | |
54 | Force PWM polarity to active high (DANGEROUS). Some chips are |
55 | misconfigured by BIOS - PWM values would be inverted. This option tries |
56 | to fix this. Please contact your BIOS manufacturer and ask him for fix. |
57 | |
58 | |
59 | Hardware Interfaces |
60 | ------------------- |
61 | |
62 | All the chips suported by this driver are LPC Super-I/O chips, accessed |
63 | through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an |
64 | SMBus interface to the hardware monitoring functions. This driver no |
65 | longer supports this interface though, as it is slower and less reliable |
66 | than the ISA access, and was only available on a small number of |
67 | motherboard models. |
68 | |
69 | |
70 | Description |
71 | ----------- |
72 | |
73 | This driver implements support for the IT8705F, IT8712F, IT8716F, |
74 | IT8718F, IT8720F, IT8721F, IT8726F, IT8758E and SiS950 chips. |
75 | |
76 | These chips are 'Super I/O chips', supporting floppy disks, infrared ports, |
77 | joysticks and other miscellaneous stuff. For hardware monitoring, they |
78 | include an 'environment controller' with 3 temperature sensors, 3 fan |
79 | rotation speed sensors, 8 voltage sensors, and associated alarms. |
80 | |
81 | The IT8712F and IT8716F additionally feature VID inputs, used to report |
82 | the Vcore voltage of the processor. The early IT8712F have 5 VID pins, |
83 | the IT8716F and late IT8712F have 6. They are shared with other functions |
84 | though, so the functionality may not be available on a given system. |
85 | |
86 | The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value |
87 | is stored in the Super-I/O configuration space. Due to technical limitations, |
88 | this value can currently only be read once at initialization time, so |
89 | the driver won't notice and report changes in the VID value. The two |
90 | upper VID bits share their pins with voltage inputs (in5 and in6) so you |
91 | can't have both on a given board. |
92 | |
93 | The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions |
94 | have support for 2 additional fans. The additional fans are supported by the |
95 | driver. |
96 | |
97 | The IT8716F, IT8718F, IT8720F and IT8721F/IT8758E, and late IT8712F and |
98 | IT8705F also have optional 16-bit tachometer counters for fans 1 to 3. This |
99 | is better (no more fan clock divider mess) but not compatible with the older |
100 | chips and revisions. The 16-bit tachometer mode is enabled by the driver when |
101 | one of the above chips is detected. |
102 | |
103 | The IT8726F is just bit enhanced IT8716F with additional hardware |
104 | for AMD power sequencing. Therefore the chip will appear as IT8716F |
105 | to userspace applications. |
106 | |
107 | Temperatures are measured in degrees Celsius. An alarm is triggered once |
108 | when the Overtemperature Shutdown limit is crossed. |
109 | |
110 | Fan rotation speeds are reported in RPM (rotations per minute). An alarm is |
111 | triggered if the rotation speed has dropped below a programmable limit. When |
112 | 16-bit tachometer counters aren't used, fan readings can be divided by |
113 | a programmable divider (1, 2, 4 or 8) to give the readings more range or |
114 | accuracy. With a divider of 2, the lowest representable value is around |
115 | 2600 RPM. Not all RPM values can accurately be represented, so some rounding |
116 | is done. |
117 | |
118 | Voltage sensors (also known as IN sensors) report their values in volts. An |
119 | alarm is triggered if the voltage has crossed a programmable minimum or |
120 | maximum limit. Note that minimum in this case always means 'closest to |
121 | zero'; this is important for negative voltage measurements. All voltage |
122 | inputs can measure voltages between 0 and 4.08 volts, with a resolution of |
123 | 0.016 volt (except IT8721F/IT8758E: 0.012 volt.) The battery voltage in8 does |
124 | not have limit registers. |
125 | |
126 | On the IT8721F/IT8758E, some voltage inputs are internal and scaled inside |
127 | the chip (in7, in8 and optionally in3). The driver handles this transparently |
128 | so user-space doesn't have to care. |
129 | |
130 | The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value: |
131 | the voltage level your processor should work with. This is hardcoded by |
132 | the mainboard and/or processor itself. It is a value in volts. |
133 | |
134 | If an alarm triggers, it will remain triggered until the hardware register |
135 | is read at least once. This means that the cause for the alarm may already |
136 | have disappeared! Note that in the current implementation, all hardware |
137 | registers are read whenever any data is read (unless it is less than 1.5 |
138 | seconds since the last update). This means that you can easily miss |
139 | once-only alarms. |
140 | |
141 | Out-of-limit readings can also result in beeping, if the chip is properly |
142 | wired and configured. Beeping can be enabled or disabled per sensor type |
143 | (temperatures, voltages and fans.) |
144 | |
145 | The IT87xx only updates its values each 1.5 seconds; reading it more often |
146 | will do no harm, but will return 'old' values. |
147 | |
148 | To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2, |
149 | or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'. |
150 | Give 0 for unused sensor. Any other value is invalid. To configure this at |
151 | startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor; |
152 | 3 = thermal diode) |
153 | |
154 | |
155 | Fan speed control |
156 | ----------------- |
157 | |
158 | The fan speed control features are limited to manual PWM mode. Automatic |
159 | "Smart Guardian" mode control handling is only implemented for older chips |
160 | (see below.) However if you want to go for "manual mode" just write 1 to |
161 | pwmN_enable. |
162 | |
163 | If you are only able to control the fan speed with very small PWM values, |
164 | try lowering the PWM base frequency (pwm1_freq). Depending on the fan, |
165 | it may give you a somewhat greater control range. The same frequency is |
166 | used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are |
167 | read-only. |
168 | |
169 | |
170 | Automatic fan speed control (old interface) |
171 | ------------------------------------------- |
172 | |
173 | The driver supports the old interface to automatic fan speed control |
174 | which is implemented by IT8705F chips up to revision F and IT8712F |
175 | chips up to revision G. |
176 | |
177 | This interface implements 4 temperature vs. PWM output trip points. |
178 | The PWM output of trip point 4 is always the maximum value (fan running |
179 | at full speed) while the PWM output of the other 3 trip points can be |
180 | freely chosen. The temperature of all 4 trip points can be freely chosen. |
181 | Additionally, trip point 1 has an hysteresis temperature attached, to |
182 | prevent fast switching between fan on and off. |
183 | |
184 | The chip automatically computes the PWM output value based on the input |
185 | temperature, based on this simple rule: if the temperature value is |
186 | between trip point N and trip point N+1 then the PWM output value is |
187 | the one of trip point N. The automatic control mode is less flexible |
188 | than the manual control mode, but it reacts faster, is more robust and |
189 | doesn't use CPU cycles. |
190 | |
191 | Trip points must be set properly before switching to automatic fan speed |
192 | control mode. The driver will perform basic integrity checks before |
193 | actually switching to automatic control mode. |
194 |
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