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1 | Kernel driver ltc4245 |
2 | ===================== |
3 | |
4 | Supported chips: |
5 | * Linear Technology LTC4245 |
6 | Prefix: 'ltc4245' |
7 | Addresses scanned: 0x20-0x3f |
8 | Datasheet: |
9 | http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 |
10 | |
11 | Author: Ira W. Snyder <iws@ovro.caltech.edu> |
12 | |
13 | |
14 | Description |
15 | ----------- |
16 | |
17 | The LTC4245 controller allows a board to be safely inserted and removed |
18 | from a live backplane in multiple supply systems such as CompactPCI and |
19 | PCI Express. |
20 | |
21 | |
22 | Usage Notes |
23 | ----------- |
24 | |
25 | This driver does not probe for LTC4245 devices, due to the fact that some |
26 | of the possible addresses are unfriendly to probing. You will have to |
27 | instantiate the devices explicitly. |
28 | |
29 | Example: the following will load the driver for an LTC4245 at address 0x23 |
30 | on I2C bus #1: |
31 | $ modprobe ltc4245 |
32 | $ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device |
33 | |
34 | |
35 | Sysfs entries |
36 | ------------- |
37 | |
38 | The LTC4245 has built-in limits for over and under current warnings. This |
39 | makes it very likely that the reference circuit will be used. |
40 | |
41 | This driver uses the values in the datasheet to change the register values |
42 | into the values specified in the sysfs-interface document. The current readings |
43 | rely on the sense resistors listed in Table 2: "Sense Resistor Values". |
44 | |
45 | in1_input 12v input voltage (mV) |
46 | in2_input 5v input voltage (mV) |
47 | in3_input 3v input voltage (mV) |
48 | in4_input Vee (-12v) input voltage (mV) |
49 | |
50 | in1_min_alarm 12v input undervoltage alarm |
51 | in2_min_alarm 5v input undervoltage alarm |
52 | in3_min_alarm 3v input undervoltage alarm |
53 | in4_min_alarm Vee (-12v) input undervoltage alarm |
54 | |
55 | curr1_input 12v current (mA) |
56 | curr2_input 5v current (mA) |
57 | curr3_input 3v current (mA) |
58 | curr4_input Vee (-12v) current (mA) |
59 | |
60 | curr1_max_alarm 12v overcurrent alarm |
61 | curr2_max_alarm 5v overcurrent alarm |
62 | curr3_max_alarm 3v overcurrent alarm |
63 | curr4_max_alarm Vee (-12v) overcurrent alarm |
64 | |
65 | in5_input 12v output voltage (mV) |
66 | in6_input 5v output voltage (mV) |
67 | in7_input 3v output voltage (mV) |
68 | in8_input Vee (-12v) output voltage (mV) |
69 | |
70 | in5_min_alarm 12v output undervoltage alarm |
71 | in6_min_alarm 5v output undervoltage alarm |
72 | in7_min_alarm 3v output undervoltage alarm |
73 | in8_min_alarm Vee (-12v) output undervoltage alarm |
74 | |
75 | in9_input GPIO voltage data (see note 1) |
76 | in10_input GPIO voltage data (see note 1) |
77 | in11_input GPIO voltage data (see note 1) |
78 | |
79 | power1_input 12v power usage (mW) |
80 | power2_input 5v power usage (mW) |
81 | power3_input 3v power usage (mW) |
82 | power4_input Vee (-12v) power usage (mW) |
83 | |
84 | |
85 | Note 1 |
86 | ------ |
87 | |
88 | If you have NOT configured the driver to sample all GPIO pins as analog |
89 | voltages, then the in10_input and in11_input sysfs attributes will not be |
90 | created. The driver will sample the GPIO pin that is currently connected to the |
91 | ADC as an analog voltage, and report the value in in9_input. |
92 | |
93 | If you have configured the driver to sample all GPIO pins as analog voltages, |
94 | then they will be sampled in round-robin fashion. If userspace reads too |
95 | slowly, -EAGAIN will be returned when you read the sysfs attribute containing |
96 | the sensor reading. |
97 | |
98 | The LTC4245 chip can be configured to sample all GPIO pins with two methods: |
99 | 1) platform data -- see include/linux/i2c/ltc4245.h |
100 | 2) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip |
101 | |
102 | The default mode of operation is to sample a single GPIO pin. |
103 |
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