hwmon: Add support for SPD5118 compliant temperature sensors

Add support for SPD5118 (Jedec JESD300) compliant temperature
sensors. Such sensors are typically found on DDR5 memory modules.

Cc: René Rebe <rene@exactcode.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Stephen Horvath <s.horvath@outlook.com.au>
Tested-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -215,6 +215,7 @@ Hardware Monitoring Kernel Drivers
    smsc47m192
    smsc47m1
    sparx5-temp
+   spd5118
    stpddc60
    surface_fan
    sy7636a-hwmon

Documentation/hwmon/spd5118.rst

+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver spd5118
+=====================
+
+Supported chips:
+
+  * SPD5118 (JEDEC JESD300) compliant temperature sensor chips
+
+    JEDEC standard download:
+	https://www.jedec.org/standards-documents/docs/jesd300-5b01
+	(account required)
+
+
+    Prefix: 'spd5118'
+
+    Addresses scanned: I2C 0x50 - 0x57
+
+Author:
+	Guenter Roeck <linux@roeck-us.net>
+
+
+Description
+-----------
+
+This driver implements support for SPD5118 (JEDEC JESD300) compliant temperature
+sensors, which are used on many DDR5 memory modules. Some systems use the sensor
+to prevent memory overheating by automatically throttling the memory controller.
+
+The driver auto-detects SPD5118 compliant chips, but can also be instantiated
+using devicetree/firmware nodes.
+
+A SPD5118 compliant chip supports a single temperature sensor. Critical minimum,
+minimum, maximum, and critical temperature can be configured. There are alarms
+for low critical, low, high, and critical thresholds.
+
+
+Hardware monitoring sysfs entries
+---------------------------------
+
+======================= ==================================
+temp1_input		Temperature (RO)
+temp1_lcrit		Low critical high temperature (RW)
+temp1_min		Minimum temperature (RW)
+temp1_max		Maximum temperature (RW)
+temp1_crit		Critical high temperature (RW)
+
+temp1_lcrit_alarm	Temperature low critical alarm
+temp1_min_alarm		Temperature low alarm
+temp1_max_alarm		Temperature high alarm
+temp1_crit_alarm	Temperature critical alarm
+======================= ==================================
+
+Alarm attributes are sticky until read and will be cleared afterwards
+unless the alarm condition still applies.

drivers/hwmon/Kconfig

@@ -2181,6 +2181,18 @@ config SENSORS_INA3221
 	  This driver can also be built as a module. If so, the module
 	  will be called ina3221.
 
+config SENSORS_SPD5118
+	tristate "SPD5118 Compliant Temperature Sensors"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for SPD5118 (JEDEC JESD300)
+	  compliant temperature sensors. Such sensors are found on DDR5 memory
+	  modules.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called spd5118.
+
 config SENSORS_TC74
 	tristate "Microchip TC74"
 	depends on I2C

drivers/hwmon/Makefile

@@ -207,6 +207,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
+obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
 obj-$(CONFIG_SENSORS_SURFACE_FAN)+= surface_fan.o
 obj-$(CONFIG_SENSORS_SY7636A)	+= sy7636a-hwmon.o