[PATCH v2 1/2] dt-bindings: arm: stm32: add simple-mfd compatible for tamp node

[Ahmad Fatoum]

The stm32mp1 TAMP (Tamper and backup registers) does tamper detection
and features 32 backup registers that, being in the RTC domain, may
survive even with Vdd switched off.

This makes it suitable for use to communicate a reboot mode from OS
to bootloader via the syscon-reboot-mode binding. Add a "simple-mfd"
to support probing such a child node. The actual reboot mode
node could then be defined in a board.dts or fixed up by the bootloader.

Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
v1 available here:
https://lore.kernel.org/linux-arm-kernel/20200916142216.25142-1-a.fatoum@xxxxxxxxxxxxxx/

v1 -> v2:
 - new patch, rebased on top of
   https://lore.kernel.org/r/20201014125441.2457-1-arnaud.pouliquen@xxxxxx
---
 .../devicetree/bindings/arm/stm32/st,stm32-syscon.yaml       | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml b/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
index 6634b3e0853e..4684017a42e4 100644
--- a/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
+++ b/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
@@ -19,8 +19,11 @@ properties:
               - st,stm32mp151-pwr-mcu
               - st,stm32-syscfg
               - st,stm32-power-config
-              - st,stm32-tamp
           - const: syscon
+      - items:
+          - const: st,stm32-tamp
+          - const: syscon
+          - const: simple-mfd
 
   reg:
     maxItems: 1
-- 
2.28.0