Re: [PATCH 2/5] power: reset: qcom-pon: Add support for WARM reset

[Krzysztof Kozlowski <krzk@kernel.org>]

On Mon, Nov 03, 2025 at 07:20:03PM +0100, Loic Poulain wrote:
> This mechanism can be used when firmware lacks proper warm-reset handling,
> for example, when the PSCI SYSTEM_RESET2 function is not implemented.
> It enables the warm reset functionality via the PMIC.
> 
> This fallback is only enabled if qcom,warm-reset property is present.
> 
> Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
> ---
>  drivers/power/reset/qcom-pon.c | 47 ++++++++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/drivers/power/reset/qcom-pon.c b/drivers/power/reset/qcom-pon.c
> index 7e108982a582..684e9fe9987d 100644
> --- a/drivers/power/reset/qcom-pon.c
> +++ b/drivers/power/reset/qcom-pon.c
> @@ -19,12 +19,20 @@
>  
>  #define NO_REASON_SHIFT			0
>  
> +#define PON_SW_RESET_S2_CTL				0x62
> +#define		PON_SW_RESET_S2_CTL_WARM_RST	0x01
> +#define PON_SW_RESET_S2_CTL2				0x63
> +#define		PON_SW_RESET_S2_CTL2_RST_EN	BIT(7)
> +#define PON_SW_RESET_GO					0x64
> +#define		PON_SW_RESET_GO_MAGIC		0xa5
> +
>  struct qcom_pon {
>  	struct device *dev;
>  	struct regmap *regmap;
>  	u32 baseaddr;
>  	struct reboot_mode_driver reboot_mode;
>  	long reason_shift;
> +	bool warm_reset;
>  };
>  
>  static int qcom_pon_reboot_mode_write(struct reboot_mode_driver *reboot,
> @@ -44,6 +52,37 @@ static int qcom_pon_reboot_mode_write(struct reboot_mode_driver *reboot,
>  	return ret;
>  }
>  
> +static int pm8916_pon_reset(struct sys_off_data *data)
> +{
> +	struct qcom_pon *pon = data->cb_data;
> +	int ret;
> +
> +	if (!pon->warm_reset || data->mode != REBOOT_WARM)
> +		return NOTIFY_DONE;

And here is proof from the binding - you just tell what the drivers
should do.

Best regards,
Krzysztof