Hello Rob, On 10/26/20 3:36 PM, Rob Herring wrote: > On Wed, Oct 21, 2020 at 12:28:55PM +0200, Ahmad Fatoum wrote: >> 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. > > 'simple-mfd' implies there is no dependency on the parent node for the > child (such as the regmap perhaps). Is that the case here? No, there's a dependency and the Linux driver does syscon_node_to_regmap on the device tree node's parent but that's how the syscon-reboot-mode binding is documented: The SYSCON mapped register is retrieved from the parental dt-node plus the offset. So the SYSCON reboot-mode node should be represented as a sub-node of a "syscon", "simple-mfd" node. How would you prefer this being done instead? Cheers, Ahmad > >> >> 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 >> > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
