Hi everybody, I'm trying to add ntc thermistor as hwmon in linux. Firts I 
tried to add hwmon manually, but I simple dont know how. Now I'm trying to 
create device tree overlay, but I have no luck.

I compiled ntc_thermistor module out-of-tree and loaded to kernel. I think 
this is ok.

# modinfo ntc_thermistor.ko

filename:       /root/ntc_thermistor/ntc_thermistor.ko
alias:          platform:ntc-thermistor
license:        GPL
author:         MyungJoo Ham <[email protected]>
description:    NTC Thermistor Driver
srcversion:     DBAD01E8C409F3A3514FAD2
depends:
vermagic:       3.8.13-35-ARCH SMP mod_unload modversions ARMv7 p2v8


# lsmod

Module                  Size  Used by
ntc_thermistor          4075  0
omap_rng                4599  0
autofs4                21976  2


My .dts file looks like this

/dts-v1/;
/plugin/;

/ {
compatible = "ti,beaglebone", "ti,beaglebone-black";

/* identification */
part-number = "BB-NTC";
version = "00A0";

/* state the resources this cape uses */
exclusive-use =
/* the pin header uses */
"P9.39", /* AIN0 */
"P9.40", /* AIN1 */
"P9.37", /* AIN2 */
"P9.38", /* AIN3 */
"P9.33", /* AIN4 */
"P9.36", /* AIN5 */
"P9.35", /* AIN6 */
/* the hardware IP uses */
"tscadc";

fragment@0 {
target = <&ocp>;
__overlay__ {
/* avoid stupid warning */
#address-cells = <1>;
#size-cells = <1>;

tscadc {
compatible = "ti,ti-tscadc";
reg = <0x44e0d000 0x1000>;

interrupt-parent = <&intc>;
interrupts = <16>;
ti,hwmods = "adc_tsc";
status = "okay";

adc {
ti,adc-channels = <0 1 2 3 4 5 6 7>;
};

};

ntc@0 {
compatible = "ntc,ncp15wb473";
  pullup-uv = <1800000>;
  pullup-ohm = <0>;
  pulldown-ohm = <12000>;
  io-channels = <&tscadc 0>;
};

test_helper: helper {
compatible = "bone-iio-helper";
vsense-name  = "AIN0", "AIN1", "AIN2", "AIN3", "AIN4", "AIN5", "AIN6", 
"AIN7";
vsense-scale = <100     100     100     100     100     100     100     
100>;
status = "okay";
};
};
};
};


After I add .dtbo to capemgr it looks like everything is ok.

#dmesg

[  102.513840] bone-capemgr bone_capemgr.9: part_number 'BB-NTC', version 
'N/A'
[  102.514030] bone-capemgr bone_capemgr.9: slot #10: generic override
[  102.514081] bone-capemgr bone_capemgr.9: bone: Using override eeprom 
data at slot 10
[  102.514134] bone-capemgr bone_capemgr.9: slot #10: 'Override Board 
Name,00A0,Override Manuf,BB-NTC'
[  102.514409] bone-capemgr bone_capemgr.9: slot #10: Requesting part 
number/version based 'BB-NTC-00A0.dtbo
[  102.514463] bone-capemgr bone_capemgr.9: slot #10: Requesting firmware 
'BB-NTC-00A0.dtbo' for board-name 'Override Board Name', version '00A0'
[  102.521859] bone-capemgr bone_capemgr.9: slot #10: dtbo 
'BB-NTC-00A0.dtbo' loaded; converting to live tree
[  102.525143] bone-capemgr bone_capemgr.9: slot #10: #1 overlays
[  102.551219] bone-iio-helper helper.16: ready
[  102.551443] bone-capemgr bone_capemgr.9: slot #10: Applied #1 overlays.

 

I'm expecting to see hwmon1 in /sys/class/hwmon/, but there is still only 
hwmon0 from am33xx internal temp sensor.  

I would really appreciate any help. 
PS: I still not added compensation table for my NTC to module, but this is 
test only. 


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