hwmon: (ntc-thermistor) Add Murata ncp18wm474

Add support for the Murata NCP18WM474 NTC.
Compensation table has been constructed by linear interpolation between
well defined points[1] on the resistance vs. temperature graph in the
datasheet[2]. The readouts of the graph has been done to the best of my
abilities, but the compensation table will be subject to inaccuracies
nonetheless.

[1] -40, -25, 0, 25, 50, 75, 100, 125 degrees
[2] https://www.murata.com/en-eu/api/pdfdownloadapi?cate=&partno=NCP18WM474E03RB

Signed-off-by: Emil Dahl Juhl <juhl.emildahl@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20251001-ntc-thermistor-ncp18wm474-v1-1-2c64b9b509ff@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index d21f7266c4119b3d0190cafd0f376874535de5cf..d6b48178343dbbf268f54004c1f6e39d97fbd532 100644 (file)
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -24,6 +24,7 @@ enum ntc_thermistor_type {
        TYPE_NCPXXWF104,
        TYPE_NCPXXWL333,
        TYPE_NCPXXXH103,
+       TYPE_NCPXXWM474,
 };
 
 struct ntc_compensation {
@@ -46,6 +47,7 @@ enum {
        NTC_NCP18WB473,
        NTC_NCP21WB473,
        NTC_SSG1404001221,
+       NTC_NCP18WM474,
        NTC_LAST,
 };
 
@@ -60,6 +62,7 @@ static const struct platform_device_id ntc_thermistor_id[] = {
        [NTC_NCP18WB473]      = { "ncp18wb473",      TYPE_NCPXXWB473 },
        [NTC_NCP21WB473]      = { "ncp21wb473",      TYPE_NCPXXWB473 },
        [NTC_SSG1404001221]   = { "ssg1404_001221",  TYPE_NCPXXWB473 },
+       [NTC_NCP18WM474]      = { "ncp18wm474",      TYPE_NCPXXWM474 },
        [NTC_LAST]            = { },
 };
 MODULE_DEVICE_TABLE(platform, ntc_thermistor_id);
@@ -217,6 +220,43 @@ static const struct ntc_compensation ncpXXxh103[] = {
        { .temp_c       = 125, .ohm     = 531 },
 };
 
+static const struct ntc_compensation ncpXXwm474[] = {
+       { .temp_c       = -40, .ohm     = 10900000 },
+       { .temp_c       = -35, .ohm     = 9600000 },
+       { .temp_c       = -30, .ohm     = 8300000 },
+       { .temp_c       = -25, .ohm     = 7000000 },
+       { .temp_c       = -20, .ohm     = 5980000 },
+       { .temp_c       = -15, .ohm     = 4960000 },
+       { .temp_c       = -10, .ohm     = 3940000 },
+       { .temp_c       = -5, .ohm      = 2920000 },
+       { .temp_c       = 0, .ohm       = 1900000 },
+       { .temp_c       = 5, .ohm       = 1614000 },
+       { .temp_c       = 10, .ohm      = 1328000 },
+       { .temp_c       = 15, .ohm      = 1042000 },
+       { .temp_c       = 20, .ohm      = 756000 },
+       { .temp_c       = 25, .ohm      = 470000 },
+       { .temp_c       = 30, .ohm      = 404000 },
+       { .temp_c       = 35, .ohm      = 338000 },
+       { .temp_c       = 40, .ohm      = 272000 },
+       { .temp_c       = 45, .ohm      = 206000 },
+       { .temp_c       = 50, .ohm      = 140000 },
+       { .temp_c       = 55, .ohm      = 122000 },
+       { .temp_c       = 60, .ohm      = 104000 },
+       { .temp_c       = 65, .ohm      = 86000 },
+       { .temp_c       = 70, .ohm      = 68000 },
+       { .temp_c       = 75, .ohm      = 50000 },
+       { .temp_c       = 80, .ohm      = 44200 },
+       { .temp_c       = 85, .ohm      = 38400 },
+       { .temp_c       = 90, .ohm      = 32600 },
+       { .temp_c       = 95, .ohm      = 26800 },
+       { .temp_c       = 100, .ohm     = 21000 },
+       { .temp_c       = 105, .ohm     = 18600 },
+       { .temp_c       = 110, .ohm     = 16200 },
+       { .temp_c       = 115, .ohm     = 13800 },
+       { .temp_c       = 120, .ohm     = 11400 },
+       { .temp_c       = 125, .ohm     = 9000 },
+};
+
 /*
  * The following compensation tables are from the specifications in EPCOS NTC
  * Thermistors Datasheets
@@ -319,6 +359,7 @@ static const struct ntc_type ntc_type[] = {
        NTC_TYPE(TYPE_NCPXXWF104,  ncpXXwf104),
        NTC_TYPE(TYPE_NCPXXWL333,  ncpXXwl333),
        NTC_TYPE(TYPE_NCPXXXH103,  ncpXXxh103),
+       NTC_TYPE(TYPE_NCPXXWM474,  ncpXXwm474),
 };
 
 /*
@@ -675,6 +716,8 @@ static const struct of_device_id ntc_match[] = {
                .data = &ntc_thermistor_id[NTC_NCP21WB473] },
        { .compatible = "samsung,1404-001221",
                .data = &ntc_thermistor_id[NTC_SSG1404001221] },
+       { .compatible = "murata,ncp18wm474",
+               .data = &ntc_thermistor_id[NTC_NCP18WM474] },
 
        /* Usage of vendor name "ntc" is deprecated */
        { .compatible = "ntc,ncp03wb473",