Re: [PATCH 2/2] pinctrl: spacemit: support I/O power domain configuration

[Inochi Amaoto <inochiama@gmail.com>]

On Tue, Dec 23, 2025 at 05:11:12PM +0800, Troy Mitchell wrote:
> IO domain power control registers are used to configure the operating
> voltage of dual-voltage GPIO banks. By default, these registers are
> configured for 3.3V operation. As a result, even when a GPIO bank is
> externally supplied with 1.8V, the internal logic continues to
> operate in the 3.3V domain, which may lead to functional failures.
> 
> This patch adds support for programming the IO domain power control
> registers, allowing dual-voltage GPIO banks to be explicitly configured
> for 1.8V operation when required.
> 
> Care must be taken when configuring these registers. If a GPIO bank is
> externally supplied with 3.3V while the corresponding IO power domain
> is configured for 1.8V, external current injection (back-powering)
> may occur, potentially causing damage to the GPIO pin.
> 
> Due to these hardware constraints and safety considerations, the IO
> domain power control registers are implemented as secure registers.
> Access to these registers requires unlocking via the AIB Secure Access
> Register (ASAR) in the APBC block before a single read or write
> operation can be performed.
> 
> Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
> ---
>  arch/riscv/boot/dts/spacemit/k1.dtsi  |   4 +-
>  drivers/pinctrl/spacemit/pinctrl-k1.c | 131 +++++++++++++++++++++++++++++++++-
>  2 files changed, 131 insertions(+), 4 deletions(-)
> 

> diff --git a/arch/riscv/boot/dts/spacemit/k1.dtsi b/arch/riscv/boot/dts/spacemit/k1.dtsi
> index 7818ca4979b6a7755722919a5958512aa11950ab..23ecb19624f227f3c39de35bf3078379f7a2490e 100644
> --- a/arch/riscv/boot/dts/spacemit/k1.dtsi
> +++ b/arch/riscv/boot/dts/spacemit/k1.dtsi
> @@ -565,10 +565,12 @@ i2c8: i2c@d401d800 {
>  
>  		pinctrl: pinctrl@d401e000 {
>  			compatible = "spacemit,k1-pinctrl";
> -			reg = <0x0 0xd401e000 0x0 0x400>;
> +			reg = <0x0 0xd401e000 0x0 0x400>,
> +			      <0x0 0xd401e800 0x0 0x34>;
>  			clocks = <&syscon_apbc CLK_AIB>,
>  				 <&syscon_apbc CLK_AIB_BUS>;
>  			clock-names = "func", "bus";
> +			spacemit,apbc = <&syscon_apbc 0x50>;
>  		};

This change breaks binding, can we use something like <0x0 0xd401e000 0x0 0x1000>?
If you insist on a new reg field, you should change the binding as well.

Regards,
Inochi