diff options
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 70 |
1 files changed, 68 insertions, 2 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index c7b8a8e787e2..067692626cf0 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -574,6 +574,41 @@ static inline int w1_DS18S20_convert_time(struct w1_slave *sl) return SLAVE_CONV_TIME_OVERRIDE(sl); } +static inline int w1_DS1825_convert_time(struct w1_slave *sl) +{ + int ret; + + if (!sl->family_data) + return -ENODEV; /* device unknown */ + + if (SLAVE_CONV_TIME_OVERRIDE(sl) != CONV_TIME_DEFAULT) + return SLAVE_CONV_TIME_OVERRIDE(sl); + + /* Return the conversion time, depending on resolution, + * select maximum conversion time among all compatible devices + */ + switch (SLAVE_RESOLUTION(sl)) { + case 9: + ret = 95; + break; + case 10: + ret = 190; + break; + case 11: + ret = 375; + break; + case 12: + ret = 750; + break; + case 14: + ret = 100; /* MAX31850 only. Datasheet says 100ms */ + break; + default: + ret = 750; + } + return ret; +} + static inline int w1_DS18B20_write_data(struct w1_slave *sl, const u8 *data) { @@ -594,6 +629,7 @@ static inline int w1_DS18B20_set_resolution(struct w1_slave *sl, int val) /* DS18B20 resolution is 9 to 12 bits */ /* GX20MH01 resolution is 9 to 14 bits */ + /* MAX31850 resolution is fixed 14 bits */ if (val < W1_THERM_RESOLUTION_MIN || val > W1_THERM_RESOLUTION_MAX) return -EINVAL; @@ -649,6 +685,7 @@ static inline int w1_DS18B20_get_resolution(struct w1_slave *sl) + W1_THERM_RESOLUTION_MIN; /* GX20MH01 has one special case: * >=14 means 14 bits when getting resolution from bit value. + * MAX31850 delivers fixed 15 and has 14 bits. * Other devices have no more then 12 bits. */ if (resolution > W1_THERM_RESOLUTION_MAX) @@ -715,6 +752,34 @@ static inline int w1_DS18S20_convert_temp(u8 rom[9]) return t; } +/** + * w1_DS1825_convert_temp() - temperature computation for DS1825 + * @rom: data read from device RAM (8 data bytes + 1 CRC byte) + * + * Can be called for any DS1825 compliant device. + * Is used by MAX31850, too + * + * Return: value in millidegrees Celsius. + */ + +static inline int w1_DS1825_convert_temp(u8 rom[9]) +{ + u16 bv; + s16 t; + + /* Signed 16-bit value to unsigned, cpu order */ + bv = le16_to_cpup((__le16 *)rom); + + /* Config register bit 7 = 1 - MA31850 found, 14 bit resolution */ + if (rom[4] & 0x80) { + /* Mask out bits 0 (Fault) and 1 (Reserved) */ + /* Avoid arithmetic shift of signed value */ + bv = (bv & 0xFFFC); /* Degrees, lowest 4 bits are 2^-1, 2^-2 and 2 zero bits */ + } + t = (s16)bv; /* Degrees, lowest bit is 2^-4 */ + return (int)t * 1000 / 16; /* Sign-extend to int; millidegrees */ +} + /* Device capability description */ /* GX20MH01 device shares family number and structure with DS18B20 */ @@ -757,9 +822,10 @@ static struct w1_therm_family_converter w1_therm_families[] = { .bulk_read = false }, { + /* Also used for MAX31850 */ .f = &w1_therm_family_DS1825, - .convert = w1_DS18B20_convert_temp, - .get_conversion_time = w1_DS18B20_convert_time, + .convert = w1_DS1825_convert_temp, + .get_conversion_time = w1_DS1825_convert_time, .set_resolution = w1_DS18B20_set_resolution, .get_resolution = w1_DS18B20_get_resolution, .write_data = w1_DS18B20_write_data, |