[Skiboot] [PATCH v4 RESEND 5/8] doc/device-tree: Add documentation for ibm, cpu-idle-state-* properties

Shreyas B. Prabhu shreyas at linux.vnet.ibm.com
Fri Jun 17 14:21:48 AEST 2016

Add documentation for following nodes-
	ibm,cpu-idle-state-pmicr ibm,cpu-idle-state-pmicr-mask
	ibm,cpu-idle-state-psscr ibm,cpu-idle-state-psscr-mask

Also removing ibm,cpu-idle-state-names from FIXME since its
already documented.

Acked-by: Michael Neuling <mikey at neuling.org>
Signed-off-by: Shreyas B. Prabhu <shreyas at linux.vnet.ibm.com>
 doc/device-tree/ibm,opal/power-mgt.txt | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/doc/device-tree/ibm,opal/power-mgt.txt b/doc/device-tree/ibm,opal/power-mgt.txt
index d9cadb87fdea..ca3487d492d8 100644
--- a/doc/device-tree/ibm,opal/power-mgt.txt
+++ b/doc/device-tree/ibm,opal/power-mgt.txt
@@ -26,6 +26,33 @@ ibm,cpu-idle-state-residency-ns = <0x1 0x2 0x3>
 ibm,cpu-idle-state-latencies-ns = <0x1 0x2 0x3>
+ibm,cpu-idle-state-pmicr ibm,cpu-idle-state-pmicr-mask
+In POWER8, idle states sleep and winkle have 2 modes- fast and deep. In fast
+mode, idle state puts the core into threshold voltage whereas deep mode
+completely turns off the core. Choosing fast vs deep mode for an idle state
+can be done either via PM_GP1 scom or by writing to PMICR special register.
+If using the PMICR path to choose fast/deep mode then ibm,cpu-idle-state-pmicr
+and ibm,cpu-idle-state-pmicr-mask properties expose relevant PMICR bits and
+values for corresponding idle states.
+ibm,cpu-idle-state-psscr ibm,cpu-idle-state-psscr-mask
+In POWER ISA v3, there is a common instruction 'stop' to enter any idle state
+and SPR PSSCR is used to specify which idle state needs to be entered upon
+executing stop instruction. Properties ibm,cpu-idle-state-psscr and
+ibm,cpu-idle-state-psscr-mask expose the relevant PSSCR bits and values for
+corresponding idle states.
+These flags are used to describe the characteristics of the idle states like
+the kind of core state loss caused. These flags are used by the kernel to
+save/restore appropriate context while using the idle states.
@@ -67,8 +94,3 @@ ibm,pstate-core-max
 This property is added when ultra_turbo(WOF) is enabled. This property gives
 the list of max pstate for each 'n' number of active cores in the chip.
-FIXME: document these:

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