PM / Voltagedomain: OMAP: Add support for absolute max voltage for a domain

We need to mark the voltage domain absolute maximum rating. This allows
us to setup voltage for a domain from min to max absolute rating.
Unfortunately, it is not possible to solely depend on maximum OPP
allowed for a domain due to the following:
in the case of a ganged voltage rail, where SMPS_x is shared between
VDD_A and VDD_B, setting voltage_tol for VDD_A can prevent VDD_B from
achieving voltage required for the domain. example:
vdd_A requires voltage Z, vdd_B requires voltage Y,
      setting Z-tol to Z + tol will not work when Y is > or < the range.
instead, we look for absolute max for the voltage domains A and B.
setting Z-tol to MAX_A and Y-tol to MAX_B allows voltage ranges which
fall in the intermediate ranges and work for both VDD_A and VDD_B even
if it may be suboptimal for one of them.

If the max range is not provided the mandatory tolerance is used.

Reported-by: Ravikumar Kattekola <rk@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/power/voltdm/voltdm_omap.txt b/Documentation/devicetree/bindings/power/voltdm/voltdm_omap.txt
index cb1fb3117c7..5b5a8857db3 100644
--- a/Documentation/devicetree/bindings/power/voltdm/voltdm_omap.txt
+++ b/Documentation/devicetree/bindings/power/voltdm/voltdm_omap.txt
@@ -25,6 +25,9 @@ Required Properties:
 	volt: voltage in uV - reference voltage (OPP voltage)
 	efuse_offseet: efuse offset from reg where the optimized voltage is stored.
 
+Optional Properties:
+- ti,absolute-max-voltage-uv: absolute maximum voltage for the voltage domain.
+
 Example:
 voltage_domain_mpu: voltdm@1 {
 	compatible = "ti,omap-voltdm";