1 Kernel driver ltc4245 1 Kernel driver ltc4245
2 ===================== 2 =====================
3 3
4 Supported chips: 4 Supported chips:
5 5
6 * Linear Technology LTC4245 6 * Linear Technology LTC4245
7 7
8 Prefix: 'ltc4245' 8 Prefix: 'ltc4245'
9 9
10 Addresses scanned: 0x20-0x3f 10 Addresses scanned: 0x20-0x3f
11 11
12 Datasheet: 12 Datasheet:
13 13
14 http://www.linear.com/pc/downloadDocum 14 http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
15 15
16 Author: Ira W. Snyder <iws@ovro.caltech.edu> 16 Author: Ira W. Snyder <iws@ovro.caltech.edu>
17 17
18 18
19 Description 19 Description
20 ----------- 20 -----------
21 21
22 The LTC4245 controller allows a board to be sa 22 The LTC4245 controller allows a board to be safely inserted and removed
23 from a live backplane in multiple supply syste 23 from a live backplane in multiple supply systems such as CompactPCI and
24 PCI Express. 24 PCI Express.
25 25
26 26
27 Usage Notes 27 Usage Notes
28 ----------- 28 -----------
29 29
30 This driver does not probe for LTC4245 devices 30 This driver does not probe for LTC4245 devices, due to the fact that some
31 of the possible addresses are unfriendly to pr 31 of the possible addresses are unfriendly to probing. You will have to
32 instantiate the devices explicitly. 32 instantiate the devices explicitly.
33 33
34 Example: the following will load the driver fo 34 Example: the following will load the driver for an LTC4245 at address 0x23
35 on I2C bus #1:: 35 on I2C bus #1::
36 36
37 $ modprobe ltc4245 37 $ modprobe ltc4245
38 $ echo ltc4245 0x23 > /sys/bus/i2c/dev 38 $ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device
39 39
40 40
41 Sysfs entries 41 Sysfs entries
42 ------------- 42 -------------
43 43
44 The LTC4245 has built-in limits for over and u 44 The LTC4245 has built-in limits for over and under current warnings. This
45 makes it very likely that the reference circui 45 makes it very likely that the reference circuit will be used.
46 46
47 This driver uses the values in the datasheet t 47 This driver uses the values in the datasheet to change the register values
48 into the values specified in the sysfs-interfa 48 into the values specified in the sysfs-interface document. The current readings
49 rely on the sense resistors listed in Table 2: 49 rely on the sense resistors listed in Table 2: "Sense Resistor Values".
50 50
51 ======================= ====================== 51 ======================= =======================================================
52 in1_input 12v input voltage (mV) 52 in1_input 12v input voltage (mV)
53 in2_input 5v input voltage (mV) 53 in2_input 5v input voltage (mV)
54 in3_input 3v input voltage (mV) 54 in3_input 3v input voltage (mV)
55 in4_input Vee (-12v) input volta 55 in4_input Vee (-12v) input voltage (mV)
56 56
57 in1_min_alarm 12v input undervoltage 57 in1_min_alarm 12v input undervoltage alarm
58 in2_min_alarm 5v input undervoltage 58 in2_min_alarm 5v input undervoltage alarm
59 in3_min_alarm 3v input undervoltage 59 in3_min_alarm 3v input undervoltage alarm
60 in4_min_alarm Vee (-12v) input under 60 in4_min_alarm Vee (-12v) input undervoltage alarm
61 61
62 curr1_input 12v current (mA) 62 curr1_input 12v current (mA)
63 curr2_input 5v current (mA) 63 curr2_input 5v current (mA)
64 curr3_input 3v current (mA) 64 curr3_input 3v current (mA)
65 curr4_input Vee (-12v) current (mA 65 curr4_input Vee (-12v) current (mA)
66 66
67 curr1_max_alarm 12v overcurrent alarm 67 curr1_max_alarm 12v overcurrent alarm
68 curr2_max_alarm 5v overcurrent alarm 68 curr2_max_alarm 5v overcurrent alarm
69 curr3_max_alarm 3v overcurrent alarm 69 curr3_max_alarm 3v overcurrent alarm
70 curr4_max_alarm Vee (-12v) overcurrent 70 curr4_max_alarm Vee (-12v) overcurrent alarm
71 71
72 in5_input 12v output voltage (mV 72 in5_input 12v output voltage (mV)
73 in6_input 5v output voltage (mV 73 in6_input 5v output voltage (mV)
74 in7_input 3v output voltage (mV 74 in7_input 3v output voltage (mV)
75 in8_input Vee (-12v) output volt 75 in8_input Vee (-12v) output voltage (mV)
76 76
77 in5_min_alarm 12v output undervoltag 77 in5_min_alarm 12v output undervoltage alarm
78 in6_min_alarm 5v output undervoltag 78 in6_min_alarm 5v output undervoltage alarm
79 in7_min_alarm 3v output undervoltag 79 in7_min_alarm 3v output undervoltage alarm
80 in8_min_alarm Vee (-12v) output unde 80 in8_min_alarm Vee (-12v) output undervoltage alarm
81 81
82 in9_input GPIO voltage data (see 82 in9_input GPIO voltage data (see note 1)
83 in10_input GPIO voltage data (see 83 in10_input GPIO voltage data (see note 1)
84 in11_input GPIO voltage data (see 84 in11_input GPIO voltage data (see note 1)
85 85
86 power1_input 12v power usage (mW) 86 power1_input 12v power usage (mW)
87 power2_input 5v power usage (mW) 87 power2_input 5v power usage (mW)
88 power3_input 3v power usage (mW) 88 power3_input 3v power usage (mW)
89 power4_input Vee (-12v) power usage 89 power4_input Vee (-12v) power usage (mW)
90 ======================= ====================== 90 ======================= =======================================================
91 91
92 92
93 Note 1 93 Note 1
94 ------ 94 ------
95 95
96 If you have NOT configured the driver to sampl 96 If you have NOT configured the driver to sample all GPIO pins as analog
97 voltages, then the in10_input and in11_input s 97 voltages, then the in10_input and in11_input sysfs attributes will not be
98 created. The driver will sample the GPIO pin t 98 created. The driver will sample the GPIO pin that is currently connected to the
99 ADC as an analog voltage, and report the value 99 ADC as an analog voltage, and report the value in in9_input.
100 100
101 If you have configured the driver to sample al 101 If you have configured the driver to sample all GPIO pins as analog voltages,
102 then they will be sampled in round-robin fashi 102 then they will be sampled in round-robin fashion. If userspace reads too
103 slowly, -EAGAIN will be returned when you read 103 slowly, -EAGAIN will be returned when you read the sysfs attribute containing
104 the sensor reading. 104 the sensor reading.
105 105
106 The LTC4245 chip can be configured to sample a 106 The LTC4245 chip can be configured to sample all GPIO pins with two methods:
107 107
108 1) platform data -- see include/linux/platform 108 1) platform data -- see include/linux/platform_data/ltc4245.h
109 2) OF device tree -- add the "ltc4245,use-extr 109 2) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip
110 110
111 The default mode of operation is to sample a s 111 The default mode of operation is to sample a single GPIO pin.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.