[AST2600] PWM/TACH driver and dbus-sensor issue

[Troy Lee]

Hi Tung,

> -----Original Message-----
> From: openbmc <openbmc-
> bounces+troy_lee=aspeedtech.com at lists.ozlabs.org> On Behalf Of Tung
> Nguyen OS
> Sent: Wednesday, February 9, 2022 10:40 PM
> To: openbmc at lists.ozlabs.org
> Cc: Thu Nguyen OS <thu at os.amperecomputing.com>; Thang Nguyen OS
> <thang at os.amperecomputing.com>; Phong Vo OS
> <phong at os.amperecomputing.com>
> Subject: [AST2600] PWM/TACH driver and dbus-sensor issue
> 
> Dear community,
> We have ported the PWM/TACH hwmon driver for AST2600 from ASPEED's
> repository https://github.com/AspeedTech-BMC/linux/tree/aspeed-master-
> v5.4/drivers/hwmon to support Ampere Computing's systems. Verify with
> AST2600 EVB, i can see the driver works. However there is a concern like:
> 1. The change of hwmon fan pwm/tach in sysfs (as below), this is different
> from the ast2500 as the separated of the fan*_input and pwm1 in various
> hwmon directories. At this time, the driver doesn't exist in the OpenBMC
> linux at https://github.com/openbmc/linux. Is OpenBMC going to merge and
> keep this driver ?

Please have a look on this patch.
https://gerrit.openbmc-project.xyz/c/openbmc/dbus-sensors/+/49253

Thanks,
Troy Lee

> root at mtmitchell:~# ls -la /sys/class/hwmon/hwmon hwmon0/ hwmon1/
> hwmon2/ hwmon3/ hwmon4/ hwmon5/ hwmon6/ hwmon7/ hwmon8/
> hwmon9/ root at mtmitchell:~# ls -la /sys/class/hwmon/hwmon0/
> drwxr-xr-x    3 root     root             0 Jan  1  1970 .
> drwxr-xr-x    3 root     root             0 Jan  1  1970 ..
> lrwxrwxrwx    1 root     root             0 Feb  9 08:38 device -
> > ../../../1e610000.pwm_tach:tach
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan10_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan11_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan12_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan13_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan14_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan15_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan16_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan1_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan2_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan3_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan4_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan5_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan6_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan7_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan8_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 fan9_input
> -r--r--r--    1 root     root          4096 Feb  9 08:38 name
> lrwxrwxrwx    1 root     root             0 Feb  9 08:38 of_node -
> > ../../../../../../../../firmware/devicetree/base/ahb/apb/pwm_tach at 1e610
> 000/tach
> drwxr-xr-x    2 root     root             0 Feb  9 08:38 power
> lrwxrwxrwx    1 root     root             0 Jan  1  1970 subsystem -
> > ../../../../../../../../class/hwmon
> -rw-r--r--    1 root     root          4096 Jan  1  1970 uevent
> root at mtmitchell:~# ls -la /sys/class/hwmon/hwmon*/pwm*
> -rw-r--r--    1 root     root          4096 Feb  9 09:13
> /sys/class/hwmon/hwmon1/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 09:20
> /sys/class/hwmon/hwmon2/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon3/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon4/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon5/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon6/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon7/pwm1
> -rw-r--r--    1 root     root          4096 Feb  9 08:38
> /sys/class/hwmon/hwmon8/pwm1
> 
> 2. With above changes, the dbus-sensor for FAN/PWM shall not work
> because of the compatibility. So if OpenBMC want to keep above
> PWM/TACH driver, does any sides have the plan to support the fan sensor, if
> not, we can join and do it.
> 
> Thank you and best regards,
> Tung