]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - Documentation/hwmon/it87
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux
[mirror_ubuntu-bionic-kernel.git] / Documentation / hwmon / it87
1 Kernel driver it87
2 ==================
3
4 Supported chips:
5 * IT8603E/IT8623E
6 Prefix: 'it8603'
7 Addresses scanned: from Super I/O config space (8 I/O ports)
8 Datasheet: Not publicly available
9 * IT8705F
10 Prefix: 'it87'
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 * IT8712F
14 Prefix: 'it8712'
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 * IT8716F/IT8726F
18 Prefix: 'it8716'
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 * IT8718F
22 Prefix: 'it8718'
23 Addresses scanned: from Super I/O config space (8 I/O ports)
24 Datasheet: Once publicly available at the ITE website, but no longer
25 * IT8720F
26 Prefix: 'it8720'
27 Addresses scanned: from Super I/O config space (8 I/O ports)
28 Datasheet: Not publicly available
29 * IT8721F/IT8758E
30 Prefix: 'it8721'
31 Addresses scanned: from Super I/O config space (8 I/O ports)
32 Datasheet: Not publicly available
33 * IT8728F
34 Prefix: 'it8728'
35 Addresses scanned: from Super I/O config space (8 I/O ports)
36 Datasheet: Not publicly available
37 * IT8771E
38 Prefix: 'it8771'
39 Addresses scanned: from Super I/O config space (8 I/O ports)
40 Datasheet: Not publicly available
41 * IT8772E
42 Prefix: 'it8772'
43 Addresses scanned: from Super I/O config space (8 I/O ports)
44 Datasheet: Not publicly available
45 * IT8782F
46 Prefix: 'it8782'
47 Addresses scanned: from Super I/O config space (8 I/O ports)
48 Datasheet: Not publicly available
49 * IT8783E/F
50 Prefix: 'it8783'
51 Addresses scanned: from Super I/O config space (8 I/O ports)
52 Datasheet: Not publicly available
53 * SiS950 [clone of IT8705F]
54 Prefix: 'it87'
55 Addresses scanned: from Super I/O config space (8 I/O ports)
56 Datasheet: No longer be available
57
58 Authors:
59 Christophe Gauthron
60 Jean Delvare <jdelvare@suse.de>
61
62
63 Module Parameters
64 -----------------
65
66 * update_vbat: int
67
68 0 if vbat should report power on value, 1 if vbat should be updated after
69 each read. Default is 0. On some boards the battery voltage is provided
70 by either the battery or the onboard power supply. Only the first reading
71 at power on will be the actual battery voltage (which the chip does
72 automatically). On other boards the battery voltage is always fed to
73 the chip so can be read at any time. Excessive reading may decrease
74 battery life but no information is given in the datasheet.
75
76 * fix_pwm_polarity int
77
78 Force PWM polarity to active high (DANGEROUS). Some chips are
79 misconfigured by BIOS - PWM values would be inverted. This option tries
80 to fix this. Please contact your BIOS manufacturer and ask him for fix.
81
82
83 Hardware Interfaces
84 -------------------
85
86 All the chips supported by this driver are LPC Super-I/O chips, accessed
87 through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
88 SMBus interface to the hardware monitoring functions. This driver no
89 longer supports this interface though, as it is slower and less reliable
90 than the ISA access, and was only available on a small number of
91 motherboard models.
92
93
94 Description
95 -----------
96
97 This driver implements support for the IT8603E, IT8623E, IT8705F, IT8712F,
98 IT8716F, IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8758E, IT8771E,
99 IT8772E, IT8782F, IT8783E/F, and SiS950 chips.
100
101 These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
102 joysticks and other miscellaneous stuff. For hardware monitoring, they
103 include an 'environment controller' with 3 temperature sensors, 3 fan
104 rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
105 intrusion detection.
106
107 The IT8712F and IT8716F additionally feature VID inputs, used to report
108 the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
109 the IT8716F and late IT8712F have 6. They are shared with other functions
110 though, so the functionality may not be available on a given system.
111
112 The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
113 is stored in the Super-I/O configuration space. Due to technical limitations,
114 this value can currently only be read once at initialization time, so
115 the driver won't notice and report changes in the VID value. The two
116 upper VID bits share their pins with voltage inputs (in5 and in6) so you
117 can't have both on a given board.
118
119 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
120 have support for 2 additional fans. The additional fans are supported by the
121 driver.
122
123 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8782F, IT8783E/F, and late
124 IT8712F and IT8705F also have optional 16-bit tachometer counters for fans 1 to
125 3. This is better (no more fan clock divider mess) but not compatible with the
126 older chips and revisions. The 16-bit tachometer mode is enabled by the driver
127 when one of the above chips is detected.
128
129 The IT8726F is just bit enhanced IT8716F with additional hardware
130 for AMD power sequencing. Therefore the chip will appear as IT8716F
131 to userspace applications.
132
133 The IT8728F, IT8771E, and IT8772E are considered compatible with the IT8721F,
134 until a datasheet becomes available (hopefully.)
135
136 The IT8603E/IT8623E is a custom design, hardware monitoring part is similar to
137 IT8728F. It only supports 16-bit fan mode, the full speed mode of the
138 fan is not supported (value 0 of pwmX_enable).
139
140 Temperatures are measured in degrees Celsius. An alarm is triggered once
141 when the Overtemperature Shutdown limit is crossed.
142
143 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
144 triggered if the rotation speed has dropped below a programmable limit. When
145 16-bit tachometer counters aren't used, fan readings can be divided by
146 a programmable divider (1, 2, 4 or 8) to give the readings more range or
147 accuracy. With a divider of 2, the lowest representable value is around
148 2600 RPM. Not all RPM values can accurately be represented, so some rounding
149 is done.
150
151 Voltage sensors (also known as IN sensors) report their values in volts. An
152 alarm is triggered if the voltage has crossed a programmable minimum or
153 maximum limit. Note that minimum in this case always means 'closest to
154 zero'; this is important for negative voltage measurements. All voltage
155 inputs can measure voltages between 0 and 4.08 volts, with a resolution of
156 0.016 volt (except IT8603E, IT8721F/IT8758E and IT8728F: 0.012 volt.) The
157 battery voltage in8 does not have limit registers.
158
159 On the IT8603E, IT8721F/IT8758E, IT8782F, and IT8783E/F, some voltage inputs
160 are internal and scaled inside the chip:
161 * in3 (optional)
162 * in7 (optional for IT8782F and IT8783E/F)
163 * in8 (always)
164 * in9 (relevant for IT8603E only)
165 The driver handles this transparently so user-space doesn't have to care.
166
167 The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
168 the voltage level your processor should work with. This is hardcoded by
169 the mainboard and/or processor itself. It is a value in volts.
170
171 If an alarm triggers, it will remain triggered until the hardware register
172 is read at least once. This means that the cause for the alarm may already
173 have disappeared! Note that in the current implementation, all hardware
174 registers are read whenever any data is read (unless it is less than 1.5
175 seconds since the last update). This means that you can easily miss
176 once-only alarms.
177
178 Out-of-limit readings can also result in beeping, if the chip is properly
179 wired and configured. Beeping can be enabled or disabled per sensor type
180 (temperatures, voltages and fans.)
181
182 The IT87xx only updates its values each 1.5 seconds; reading it more often
183 will do no harm, but will return 'old' values.
184
185 To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
186 or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
187 Give 0 for unused sensor. Any other value is invalid. To configure this at
188 startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
189 3 = thermal diode)
190
191
192 Fan speed control
193 -----------------
194
195 The fan speed control features are limited to manual PWM mode. Automatic
196 "Smart Guardian" mode control handling is only implemented for older chips
197 (see below.) However if you want to go for "manual mode" just write 1 to
198 pwmN_enable.
199
200 If you are only able to control the fan speed with very small PWM values,
201 try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
202 it may give you a somewhat greater control range. The same frequency is
203 used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
204 read-only.
205
206
207 Automatic fan speed control (old interface)
208 -------------------------------------------
209
210 The driver supports the old interface to automatic fan speed control
211 which is implemented by IT8705F chips up to revision F and IT8712F
212 chips up to revision G.
213
214 This interface implements 4 temperature vs. PWM output trip points.
215 The PWM output of trip point 4 is always the maximum value (fan running
216 at full speed) while the PWM output of the other 3 trip points can be
217 freely chosen. The temperature of all 4 trip points can be freely chosen.
218 Additionally, trip point 1 has an hysteresis temperature attached, to
219 prevent fast switching between fan on and off.
220
221 The chip automatically computes the PWM output value based on the input
222 temperature, based on this simple rule: if the temperature value is
223 between trip point N and trip point N+1 then the PWM output value is
224 the one of trip point N. The automatic control mode is less flexible
225 than the manual control mode, but it reacts faster, is more robust and
226 doesn't use CPU cycles.
227
228 Trip points must be set properly before switching to automatic fan speed
229 control mode. The driver will perform basic integrity checks before
230 actually switching to automatic control mode.
231
232
233 Temperature offset attributes
234 -----------------------------
235
236 The driver supports temp[1-3]_offset sysfs attributes to adjust the reported
237 temperature for thermal diodes or diode-connected thermal transistors.
238 If a temperature sensor is configured for thermistors, the attribute values
239 are ignored. If the thermal sensor type is Intel PECI, the temperature offset
240 must be programmed to the critical CPU temperature.