kernel: backport and package drivetemp hwmon from v5.5

This patch backports the hwmon drivetemp sensor module from vanilla
linux 5.5 to be available on OpenWrt's 5.4 kernel.

Extract from The upstream commit by Guenter Roeck <linux@roeck-us.net>:
hwmon: Driver for disk and solid state drives with temperature sensors

"Reading the temperature of ATA drives has been supported for years
by userspace tools such as smarttools or hddtemp. The downside of
such tools is that they need to run with super-user privilege, that
the temperatures are not reported by standard tools such as 'sensors'
or 'libsensors', and that drive temperatures are not available for use
in the kernel's thermal subsystem.

This driver solves this problem by adding support for reading the
temperature of ATA drives from the kernel using the hwmon API and
by adding a temperature zone for each drive.

With this driver, the hard disk temperature can be read [...]
using sysfs:

$ grep . /sys/class/hwmon/hwmon9/{name,temp1_input}
/sys/class/hwmon/hwmon9/name:drivetemp
/sys/class/hwmon/hwmon9/temp1_input:23000

If the drive supports SCT transport and reports temperature limits,
those are reported as well.

drivetemp-scsi-0-0
Adapter: SCSI adapter
temp1:        +27.0<C2><B0>C (low  =  +0.0<C2><B0>C, high = +60.0<C2><B0>C)
                             (crit low = -41.0<C2><B0>C, crit = +85.0<C2><B0>C)
                             (lowest = +23.0<C2><B0>C, highest = +34.0<C2><B0>C)

The driver attempts to use SCT Command Transport to read the drive
temperature. If the SCT Command Transport feature set is not available,
or if it does not report the drive temperature, drive temperatures may
be readable through SMART attributes. Since SMART attributes are not well
defined, this method is only used as fallback mechanism."

This patch incorperates a patch made by Linus Walleij:
820-libata-Assign-OF-node-to-the-SCSI-device.patch
This patch is necessary in order to wire-up the drivetemp
sensor into the device tree's thermal-zones.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/package/kernel/linux/modules/hwmon.mk b/package/kernel/linux/modules/hwmon.mk
index 73b448022d..1f4e4558a9 100644
--- a/package/kernel/linux/modules/hwmon.mk
+++ b/package/kernel/linux/modules/hwmon.mk
@@ -77,6 +77,21 @@ endef
 $(eval $(call KernelPackage,hwmon-adt7475))
 
 
+define KernelPackage/hwmon-drivetemp
+  TITLE:=Hard disk drives with temperature sensor
+  KCONFIG:=CONFIG_SENSORS_DRIVETEMP
+  FILES:=$(LINUX_DIR)/drivers/hwmon/drivetemp.ko
+  AUTOLOAD:=$(call AutoLoad,60,drivetemp)
+  $(call AddDepends/hwmon,+kmod-ata-core +kmod-scsi-core)
+endef
+
+define KernelPackage/hwmon-drivetemp/description
+ Kernel module for Hard disk drives with temperature sensor
+endef
+
+$(eval $(call KernelPackage,hwmon-drivetemp))
+
+
 define KernelPackage/hwmon-gpiofan
   TITLE:=Generic GPIO FAN support
   KCONFIG:=CONFIG_SENSORS_GPIO_FAN