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| Commit | Line | Data |
|---|---|---|
| 6e34b187 IS |
1 | Kernel driver ltc4245 |
| 2 | ===================== | |
| 3 | ||
| 4 | Supported chips: | |
| b04f2f7d | 5 | |
| 6e34b187 | 6 | * Linear Technology LTC4245 |
| b04f2f7d | 7 | |
| 6e34b187 | 8 | Prefix: 'ltc4245' |
| b04f2f7d | 9 | |
| 6e34b187 | 10 | Addresses scanned: 0x20-0x3f |
| b04f2f7d | 11 | |
| 6e34b187 | 12 | Datasheet: |
| b04f2f7d MCC |
13 | |
| 14 | http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 | |
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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 | |
| 2d2a7cff JD |
31 | of the possible addresses are unfriendly to probing. You will have to |
| 32 | instantiate the devices explicitly. | |
| 6e34b187 IS |
33 | |
| 34 | Example: the following will load the driver for an LTC4245 at address 0x23 | |
| b04f2f7d MCC |
35 | on I2C bus #1:: |
| 36 | ||
| 37 | $ modprobe ltc4245 | |
| 38 | $ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device | |
| 6e34b187 IS |
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 | ||
| b04f2f7d | 51 | ======================= ======================================================= |
| 6e34b187 IS |
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 | ||
| 5950ec8d IS |
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) | |
| 6e34b187 IS |
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) | |
| b04f2f7d | 90 | ======================= ======================================================= |
| 5950ec8d IS |
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: | |
| b04f2f7d | 107 | |
| 8116e8dd | 108 | 1) platform data -- see include/linux/platform_data/ltc4245.h |
| 5950ec8d IS |
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. |