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