[Skiboot] [PATCH] SLW: Add init for power9 power management

[Vaidyanathan Srinivasan]

* Stewart Smith <stewart at linux.vnet.ibm.com> [2017-03-23 15:30:09]:

> Akshay Adiga <akshay.adiga at linux.vnet.ibm.com> writes:
> > This patch adds new function to init core for power9 power management.
> > SPECIAL_WKUP_* SCOM registers, if set, can hold the cores from going into
> > idle states. Hence, clear PPM SPECIAL_WKUP_HYP_REG scom register for each
> > core during init.
> >
> > Signed-off-by: Akshay Adiga <akshay.adiga at linux.vnet.ibm.com>
> > ---
> >  hw/slw.c        | 53 ++++++++++++++++++++++++++++++++++++++++++++++-------
> >  include/xscom.h |  6 ++++++
> >  2 files changed, 52 insertions(+), 7 deletions(-)
> 
> Hi! This breaks Mambo tests.
> 
> FYI, you can run them automatically yourself by pushing your code up to
> github after enabling travis-ci.org for your personal repository. The
> .travis.yml file in skiboot runs a wide variety of OSs and runs P8 and
> P9 mambo boot tests.
> 
> The failure is this:
> 
> 6352335: (6352335): [    0.006348678,5] SLW: Init chip 0x0
> WARNING: 6352731: (6352731): Invalid address 0x0000000100780868 in XSCOM range,  SCOM=
> 0x01007808d
> WARNING: 6352731: (6352731): Attempt to store non-existent address 0x00001A0100780868
> 6352731: (6352731): 0x000000003002E65C : stdcix  r26,r0,r3
> FATAL ERROR: 6352731: (6352731): Check Stop for 0:0: Machine Check with ME bit of MSR 
> off

Hi Stewart,

Thanks for catching this issue.  We need to skip this xscoms access
and setup on mambo. We do on P8, need to fix that code path.

I will re-spin this patch with the fix so as to not break P9 mambo.

--Vaidy