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hwmon: (lm70) Add ti,tmp125 support 

The TMP125 is a 2 degree Celsius accurate Digital
Temperature Sensor with a SPI interface.

The temperature register is a 16-bit, read-only register.
The MSB (Bit 15) is a leading zero and never set. Bits 14
to 5 are the 1+9 temperature data bits in a two's
complement format. Bits 4 to 0 are useless copies of
Bit 5 value and therefore ignored.

This was tested on a Aerohive HiveAP-350.

Bonus: lm70 supports TMP122/TMP124 as well.
I added them to the Kconfig module description.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Link: https://lore.kernel.org/r/43b19cbd4e7f51e9509e561b02b5d8d0e7079fac.1645175187.git.chunkeey@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Christian Lamparter 2022-02-18 10:06:43 +01:00 committed by Guenter Roeck
parent 64b631fb0c
commit cd929672a9
3 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Documentation/hwmon/lm70.rst
View File

@ -15,6 +15,10 @@ Supported chips:
Information: https://www.ti.com/product/tmp122
* Texas Instruments TMP125
Information: https://www.ti.com/product/tmp125
* National Semiconductor LM71
Datasheet: https://www.ti.com/product/LM71
@ -53,6 +57,9 @@ The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is
The TMP122/TMP124 also feature configurable temperature thresholds.
The TMP125 is less accurate and provides 10-bit temperature data
with 0.25 degrees Celsius resolution.
The LM71 is also very similar; main difference is 14-bit temperature
data (0.03125 degrees celsius resolution).

4
drivers/hwmon/Kconfig
View File

@ -1224,8 +1224,8 @@ config SENSORS_LM70
depends on SPI_MASTER
help
If you say yes here you get support for the National Semiconductor
LM70, LM71, LM74 and Texas Instruments TMP121/TMP123 digital tempera-
ture sensor chips.
LM70, LM71, LM74 and Texas Instruments TMP121/TMP123, TMP122/TMP124,
TMP125 digital temperature sensor chips.
This driver can also be built as a module. If so, the module
will be called lm70.

16
drivers/hwmon/lm70.c
View File

@ -34,6 +34,7 @@
#define LM70_CHIP_LM71 2 /* NS LM71 */
#define LM70_CHIP_LM74 3 /* NS LM74 */
#define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */
#define LM70_CHIP_TMP125 5 /* TI TMP125 */
struct lm70 {
struct spi_device *spi;
@ -87,6 +88,12 @@ static ssize_t temp1_input_show(struct device *dev,
* LM71:
* 14 bits of 2's complement data, discard LSB 2 bits,
* resolution 0.0312 degrees celsius.
*
* TMP125:
* MSB/D15 is a leading zero. D14 is the sign-bit. This is
* followed by 9 temperature bits (D13..D5) in 2's complement
* data format with a resolution of 0.25 degrees celsius per unit.
* LSB 5 bits (D4..D0) share the same value as D5 and get discarded.
*/
switch (p_lm70->chip) {
case LM70_CHIP_LM70:
@ -102,6 +109,10 @@ static ssize_t temp1_input_show(struct device *dev,
case LM70_CHIP_LM71:
val = ((int)raw / 4) * 3125 / 100;
break;
case LM70_CHIP_TMP125:
val = (sign_extend32(raw, 14) / 32) * 250;
break;
}
status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
@ -135,6 +146,10 @@ static const struct of_device_id lm70_of_ids[] = {
.compatible = "ti,tmp122",
.data = (void *) LM70_CHIP_TMP122,
},
{
.compatible = "ti,tmp125",
.data = (void *) LM70_CHIP_TMP125,
},
{
.compatible = "ti,lm71",
.data = (void *) LM70_CHIP_LM71,
@ -184,6 +199,7 @@ static const struct spi_device_id lm70_ids[] = {
{ "lm70", LM70_CHIP_LM70 },
{ "tmp121", LM70_CHIP_TMP121 },
{ "tmp122", LM70_CHIP_TMP122 },
{ "tmp125", LM70_CHIP_TMP125 },
{ "lm71", LM70_CHIP_LM71 },
{ "lm74", LM70_CHIP_LM74 },
{ },