Re: [PATCH v2 1/2] irqchip/riscv-imsic: Restore the IMSIC registers

["Nutty Liu" <liujingqi@lanxincomputing.com>]

On 8/6/2025 4:27 PM, Nick Hu wrote:
> When the system woken up from the low power state, the IMSIC might be in
> the reset state. Therefore adding the CPU PM callbacks to restore the
> IMSIC register when the cpu resume from the low power state.
>
> Signed-off-by: Nick Hu <nick.hu@sifive.com>
> Reviewed-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
> Reviewed-by: Cyan Yang <cyan.yang@sifive.com>
> Reviewed-by: Anup Patel <anup@brainfault.org>
> ---
>   drivers/irqchip/irq-riscv-imsic-early.c | 40 ++++++++++++++++++++-----
>   1 file changed, 32 insertions(+), 8 deletions(-)
Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>

Thanks,
Nutty
> diff --git a/drivers/irqchip/irq-riscv-imsic-early.c b/drivers/irqchip/irq-riscv-imsic-early.c
> index d9ae87808651..62bcbcae8bd4 100644
> --- a/drivers/irqchip/irq-riscv-imsic-early.c
> +++ b/drivers/irqchip/irq-riscv-imsic-early.c
> @@ -7,6 +7,7 @@
>   #define pr_fmt(fmt) "riscv-imsic: " fmt
>   #include <linux/acpi.h>
>   #include <linux/cpu.h>
> +#include <linux/cpu_pm.h>
>   #include <linux/interrupt.h>
>   #include <linux/io.h>
>   #include <linux/irq.h>
> @@ -109,14 +110,8 @@ static void imsic_handle_irq(struct irq_desc *desc)
>   	chained_irq_exit(chip, desc);
>   }
>   
> -static int imsic_starting_cpu(unsigned int cpu)
> +static void imsic_restore(void)
>   {
> -	/* Mark per-CPU IMSIC state as online */
> -	imsic_state_online();
> -
> -	/* Enable per-CPU parent interrupt */
> -	enable_percpu_irq(imsic_parent_irq, irq_get_trigger_type(imsic_parent_irq));
> -
>   	/* Setup IPIs */
>   	imsic_ipi_starting_cpu();
>   
> @@ -128,6 +123,19 @@ static int imsic_starting_cpu(unsigned int cpu)
>   
>   	/* Enable local interrupt delivery */
>   	imsic_local_delivery(true);
> +}
> +
> +static int imsic_starting_cpu(unsigned int cpu)
> +{
> +	/* Mark per-CPU IMSIC state as online */
> +	imsic_state_online();
> +
> +	/* Enable per-CPU parent interrupt */
> +	enable_percpu_irq(imsic_parent_irq,
> +			  irq_get_trigger_type(imsic_parent_irq));
> +
> +	/* Restore the imsic reg */
> +	imsic_restore();
>   
>   	return 0;
>   }
> @@ -143,6 +151,22 @@ static int imsic_dying_cpu(unsigned int cpu)
>   	return 0;
>   }
>   
> +static int imsic_pm_notifier(struct notifier_block *self, unsigned long cmd, void *v)
> +{
> +	switch (cmd) {
> +	case CPU_PM_EXIT:
> +		/* Restore the imsic reg */
> +		imsic_restore();
> +		break;
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +static struct notifier_block imsic_pm_notifier_block = {
> +	.notifier_call = imsic_pm_notifier,
> +};
> +
>   static int __init imsic_early_probe(struct fwnode_handle *fwnode)
>   {
>   	struct irq_domain *domain;
> @@ -180,7 +204,7 @@ static int __init imsic_early_probe(struct fwnode_handle *fwnode)
>   	cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_IMSIC_STARTING, "irqchip/riscv/imsic:starting",
>   			  imsic_starting_cpu, imsic_dying_cpu);
>   
> -	return 0;
> +	return cpu_pm_register_notifier(&imsic_pm_notifier_block);
>   }
>   
>   static int __init imsic_early_dt_init(struct device_node *node, struct device_node *parent)

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv