Real-time / hardware clock issues

[Vali Cobelea <valentin.cobelea@enea.com>]

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Hi guys,

We've encountered an issue whit the Keystone 2 target regarding the 
real-time / hardware clock.
The problem first appears during the boot process, as shown below in the 
log. Seems that the rtc device (eg. rtc0) is not present.

...

[    0.592146] 8021q: 802.1Q VLAN Support v1.8
[    0.592817] sctp: Hash tables configured (established 16384 bind 16384)
[    0.593721] NET: Registered protocol family 40
[    0.594339] VFP support v0.3: implementor 41 architecture 4 part 30 variant f rev 0
[    0.595360] Registering SWP/SWPB emulation handler
*[    0.596230] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)*
[    0.597856] keystone-netcp 2090000.netcp: initializing cpsw version 1.3 (1) SGMII identification value 0x4ed1
[    0.599351] keystone-netcp 2090000.netcp: Created a cpsw ale engine
[    0.600184] keystone-netcp 2090000.netcp: initialized cpsw ale revision 1.3
[    0.610193] keystone-netcp 2090000.netcp: Using Packet Accelerator Firmware version 0x01030008
[    0.611338] keystone-netcp 2090000.netcp: pa_clk_rate(204800000 HZ),mult(20000),shift(12)

...

root@keystone-evm:~# ls -al /dev/misc/rtc
ls: /dev/misc/rtc: No such file or directory

root@keystone-evm:~# ls -al /dev/rtc0
ls: /dev/rtc0: No such file or directory


Another issue, linked to the rt/hw clock and maybe to the above problem, 
can be seen while running the 'date' command, in the sense that if you 
run the command several times for *at least* 4-5 seconds, the command 
will output *only* a time change (the seconds will increment only once 
during the 4-5 seconds of 'date' command run one after another).

Was this problem reproduced by anyone else ?
Could this be
#1. a kernel missing configuration (the following are missing from the 
.config, adding them and rebuilding the kernel did not solved any of the 
issues):

CONFIG_RTC_CLASS=y
CONFIG_RTC_HCTOSYS=y
CONFIG_RTC_HCTOSYS_DEVICE="rtc0"
CONFIG_RTC_INTF_SYSFS=y
CONFIG_RTC_INTF_PROC=y
CONFIG_RTC_INTF_DEV=y

#2. or a clock frequency:
in arch/arm/boot/dts/k2hk-evm.dts we should then add the 
'clock-frequency' to a proper value:

                 timer {
                         compatible = "arm,armv7-timer";
                         interrupts = <1 13 0xf08 1 14 0xf08>;
+                        clock-frequency = <134221720>;
                 };

#3. or a hardware problem ?


We are not sure on the cause of this rt/hw clock issue yet; any 
advice/input would help us a lot.

Thank you,
Valentin

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