hwmon: Add driver for Astera Labs PT5161L retimer

This driver implements support for temperature monitoring of Astera Labs
PT5161L series PCIe retimer chips.

This driver implementation originates from the CSDK available at
Link: https://github.com/facebook/openbmc/tree/helium/common/recipes-lib/retimer-v2.14
The communication protocol utilized is based on the I2C/SMBus standard.
Signed-off-by: Cosmo Chou <chou.cosmo@gmail.com>
Link: https://lore.kernel.org/r/20240206125420.3884300-2-chou.cosmo@gmail.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -190,6 +190,7 @@ Hardware Monitoring Kernel Drivers
    pmbus
    powerz
    powr1220
+   pt5161l
    pxe1610
    pwm-fan
    q54sj108a2

Documentation/hwmon/pt5161l.rst

+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver pt5161l
+=====================
+
+Supported chips:
+
+  * Astera Labs PT5161L
+
+    Prefix: 'pt5161l'
+
+    Addresses scanned: I2C 0x20 - 0x27
+
+    Datasheet: Not publicly available.
+
+Authors: Cosmo Chou <cosmo.chou@quantatw.com>
+
+Description
+-----------
+
+This driver implements support for temperature monitoring of Astera Labs
+PT5161L series PCIe retimer chips.
+
+This driver implementation originates from the CSDK available at
+https://github.com/facebook/openbmc/tree/helium/common/recipes-lib/retimer-v2.14
+The communication protocol utilized is based on the I2C/SMBus standard.
+
+Sysfs entries
+----------------
+
+================ ==============================================
+temp1_input      Measured temperature (in millidegrees Celsius)
+================ ==============================================
+
+Debugfs entries
+----------------
+
+================ ===============================
+fw_load_status   Firmware load status
+fw_ver           Firmware version of the retimer
+heartbeat_status Heartbeat status
+================ ===============================

MAINTAINERS

@@ -17698,6 +17698,13 @@ F:	fs/pstore/
 F:	include/linux/pstore*
 K:	\b(pstore|ramoops)
 
+PT5161L HARDWARE MONITOR DRIVER
+M:	Cosmo Chou <cosmo.chou@quantatw.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/pt5161l.rst
+F:	drivers/hwmon/pt5161l.c
+
 PTP HARDWARE CLOCK SUPPORT
 M:	Richard Cochran <richardcochran@gmail.com>
 L:	netdev@vger.kernel.org

drivers/hwmon/Kconfig

@@ -1755,6 +1755,16 @@ source "drivers/hwmon/peci/Kconfig"
 
 source "drivers/hwmon/pmbus/Kconfig"
 
+config SENSORS_PT5161L
+	tristate "Astera Labs PT5161L PCIe retimer hardware monitoring"
+	depends on I2C
+	help
+	  If you say yes here you get support for temperature monitoring
+	  on the Astera Labs PT5161L PCIe retimer.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called pt5161l.
+
 config SENSORS_PWM_FAN
 	tristate "PWM fan"
 	depends on (PWM && OF) || COMPILE_TEST

drivers/hwmon/Makefile

@@ -184,6 +184,7 @@ obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
 obj-$(CONFIG_SENSORS_POWERZ)	+= powerz.o
 obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
+obj-$(CONFIG_SENSORS_PT5161L)	+= pt5161l.o
 obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o
 obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o