[PATCH 5/8] lib: sbi_irqchip: Support irqchip device targetting subset of harts

[Samuel Holland]

Hi Anup,

On 2026-02-07 4:25 AM, Anup Patel wrote:
> It is possible to have platform where an irqchip device targets
> a subset of harts and there are multiple irqchip devices to cover
> all harts.
> 
> To support this scenario:
> 1) Add target_harts hartmask to struct sbi_irqchip_device which
>    represents the set of harts targetted by the irqchip device
> 2) Call warm_init() and irq_handle() callbacks of an irqchip device
>    on a hart only if irqchip device targets that particular hart
> 
> Signed-off-by: Anup Patel <anup.patel at oss.qualcomm.com>
> ---
>  include/sbi/sbi_irqchip.h |  8 +++++--
>  lib/sbi/sbi_irqchip.c     | 48 ++++++++++++++++++++++++++++-----------
>  lib/utils/irqchip/aplic.c | 12 +++++++++-
>  lib/utils/irqchip/imsic.c |  7 ++++--
>  lib/utils/irqchip/plic.c  |  5 ++--
>  5 files changed, 59 insertions(+), 21 deletions(-)
> 
> diff --git a/include/sbi/sbi_irqchip.h b/include/sbi/sbi_irqchip.h
> index cda1e50f..c3ded271 100644
> --- a/include/sbi/sbi_irqchip.h
> +++ b/include/sbi/sbi_irqchip.h
> @@ -10,6 +10,7 @@
>  #ifndef __SBI_IRQCHIP_H__
>  #define __SBI_IRQCHIP_H__
>  
> +#include <sbi/sbi_hartmask.h>
>  #include <sbi/sbi_list.h>
>  #include <sbi/sbi_types.h>
>  
> @@ -20,11 +21,14 @@ struct sbi_irqchip_device {
>  	/** Node in the list of irqchip devices */
>  	struct sbi_dlist node;
>  
> +	/** Set of harts targetted by this irqchip */
> +	struct sbi_hartmask target_harts;
> +
>  	/** Initialize per-hart state for the current hart */
>  	int (*warm_init)(struct sbi_irqchip_device *chip);
>  
>  	/** Process hardware interrupts from this irqchip */
> -	int (*process_hwirqs)(void);
> +	int (*process_hwirqs)(struct sbi_irqchip_device *chip);
>  };
>  
>  /**
> @@ -38,7 +42,7 @@ struct sbi_irqchip_device {
>  int sbi_irqchip_process(void);
>  
>  /** Register an irqchip device to receive callbacks */
> -void sbi_irqchip_add_device(struct sbi_irqchip_device *chip);
> +int sbi_irqchip_add_device(struct sbi_irqchip_device *chip);
>  
>  /** Initialize interrupt controllers */
>  int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot);
> diff --git a/lib/sbi/sbi_irqchip.c b/lib/sbi/sbi_irqchip.c
> index 3b970527..77ec05af 100644
> --- a/lib/sbi/sbi_irqchip.c
> +++ b/lib/sbi/sbi_irqchip.c
> @@ -13,24 +13,44 @@
>  
>  static SBI_LIST_HEAD(irqchip_list);
>  
> -static int default_irqfn(void)
> +int sbi_irqchip_process(void)
>  {
> -	return SBI_ENODEV;
> -}
> +	struct sbi_irqchip_device *chip;
> +	int rc = SBI_ENODEV;
>  
> -static int (*ext_irqfn)(void) = default_irqfn;
> +	sbi_list_for_each_entry(chip, &irqchip_list, node) {
> +		if (!chip->process_hwirqs)
> +			continue;
> +		if (!sbi_hartmask_test_hartindex(current_hartindex(), &chip->target_harts))
> +			continue;
> +		rc = chip->process_hwirqs(chip);
> +		if (rc)
> +			break;

This is a hot path (used for IPIs already), so I would recommend using a
per-hart pointer to the top-level chip that gets set in
sbi_irqchip_add_device(), so there is no lookup needed here.

> +	}
>  
> -int sbi_irqchip_process(void)
> -{
> -	return ext_irqfn();
> +	return rc;
>  }
>  
> -void sbi_irqchip_add_device(struct sbi_irqchip_device *chip)
> +int sbi_irqchip_add_device(struct sbi_irqchip_device *chip)
>  {
> -	sbi_list_add_tail(&chip->node, &irqchip_list);
> +	struct sbi_irqchip_device *c;
> +	struct sbi_hartmask hm;
> +
> +	if (!chip || !sbi_hartmask_weight(&chip->target_harts))
> +		return SBI_EINVAL;
> +
> +	if (chip->process_hwirqs) {
> +		sbi_list_for_each_entry(c, &irqchip_list, node) {
> +			if (!c->process_hwirqs)
> +				continue;
> +			sbi_hartmask_and(&hm, &c->target_harts, &chip->target_harts);
> +			if (sbi_hartmask_weight(&hm))
> +				return SBI_EINVAL;
> +		}
> +	}
>  
> -	if (chip->process_hwirqs)
> -		ext_irqfn = chip->process_hwirqs;
> +	sbi_list_add_tail(&chip->node, &irqchip_list);
> +	return 0;
>  }
>  
>  int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot)
> @@ -48,12 +68,14 @@ int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot)
>  	sbi_list_for_each_entry(chip, &irqchip_list, node) {
>  		if (!chip->warm_init)
>  			continue;
> +		if (!sbi_hartmask_test_hartindex(current_hartindex(), &chip->target_harts))
> +			continue;
>  		rc = chip->warm_init(chip);
>  		if (rc)
>  			return rc;
>  	}
>  
> -	if (ext_irqfn != default_irqfn)
> +	if (!sbi_list_empty(&irqchip_list))
>  		csr_set(CSR_MIE, MIP_MEIP);

This should only enable interrupts if there is an irqchip targeting the current
hart.

Regards,
Samuel

>  
>  	return 0;
> @@ -61,6 +83,6 @@ int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot)
>  
>  void sbi_irqchip_exit(struct sbi_scratch *scratch)
>  {
> -	if (ext_irqfn != default_irqfn)
> +	if (!sbi_list_empty(&irqchip_list))
>  		csr_clear(CSR_MIE, MIP_MEIP);
>  }
> diff --git a/lib/utils/irqchip/aplic.c b/lib/utils/irqchip/aplic.c
> index 8d0db168..ea5cb7c4 100644
> --- a/lib/utils/irqchip/aplic.c
> +++ b/lib/utils/irqchip/aplic.c
> @@ -297,8 +297,18 @@ int aplic_cold_irqchip_init(struct aplic_data *aplic)
>  			return rc;
>  	}
>  
> +	if (aplic->num_idc) {
> +		for (i = 0; i < aplic->num_idc; i++)
> +			sbi_hartmask_set_hartindex(aplic->idc_map[i],
> +						   &aplic->irqchip.target_harts);
> +	} else {
> +		sbi_hartmask_set_all(&aplic->irqchip.target_harts);
> +	}
> +
>  	/* Register irqchip device */
> -	sbi_irqchip_add_device(&aplic->irqchip);
> +	rc = sbi_irqchip_add_device(&aplic->irqchip);
> +	if (rc)
> +		return rc;
>  
>  	/* Attach to the aplic list */
>  	sbi_list_add_tail(&aplic->node, &aplic_list);
> diff --git a/lib/utils/irqchip/imsic.c b/lib/utils/irqchip/imsic.c
> index 0e9917da..5ec9dff4 100644
> --- a/lib/utils/irqchip/imsic.c
> +++ b/lib/utils/irqchip/imsic.c
> @@ -147,7 +147,7 @@ int imsic_get_target_file(u32 hartindex)
>  	return imsic_get_hart_file(scratch);
>  }
>  
> -static int imsic_process_hwirqs(void)
> +static int imsic_process_hwirqs(struct sbi_irqchip_device *chip)
>  {
>  	ulong mirq;
>  
> @@ -391,7 +391,10 @@ int imsic_cold_irqchip_init(struct imsic_data *imsic)
>  	}
>  
>  	/* Register irqchip device */
> -	sbi_irqchip_add_device(&imsic_device);
> +	sbi_hartmask_set_all(&imsic_device.target_harts);
> +	rc = sbi_irqchip_add_device(&imsic_device);
> +	if (rc)
> +		return rc;
>  
>  	/* Register IPI device */
>  	sbi_ipi_add_device(&imsic_ipi_device);
> diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c
> index 7989a962..25cc2787 100644
> --- a/lib/utils/irqchip/plic.c
> +++ b/lib/utils/irqchip/plic.c
> @@ -276,11 +276,10 @@ int plic_cold_irqchip_init(struct plic_data *plic)
>  			continue;
>  
>  		plic_set_hart_data_ptr(sbi_hartindex_to_scratch(i), plic);
> +		sbi_hartmask_set_hartindex(i, &plic->irqchip.target_harts);
>  	}
>  
>  	/* Register irqchip device */
>  	plic->irqchip.warm_init = plic_warm_irqchip_init;
> -	sbi_irqchip_add_device(&plic->irqchip);
> -
> -	return 0;
> +	return sbi_irqchip_add_device(&plic->irqchip);
>  }