Re: [PATCH v6 11/17] ACPI: RISC-V: Initialize GSI mapping structures

[Lorenzo Pieralisi]

On Sat, Jun 01, 2024 at 08:34:05PM +0530, Sunil V L wrote:
> RISC-V has PLIC and APLIC in MADT as well as namespace devices.
> Initialize the list of those structures using MADT and namespace devices
> to create mapping between the ACPI handle and the GSI ranges. This will
> be used later to add dependencies.
> 
> Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
> ---
>  arch/riscv/include/asm/irq.h |  22 ++++++
>  drivers/acpi/riscv/init.c    |   2 +
>  drivers/acpi/riscv/init.h    |   4 +
>  drivers/acpi/riscv/irq.c     | 142 +++++++++++++++++++++++++++++++++++
>  4 files changed, 170 insertions(+)
>  create mode 100644 drivers/acpi/riscv/init.h
> 
> diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
> index 8e10a94430a2..44a0b128c602 100644
> --- a/arch/riscv/include/asm/irq.h
> +++ b/arch/riscv/include/asm/irq.h
> @@ -16,4 +16,26 @@ void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));
>  
>  struct fwnode_handle *riscv_get_intc_hwnode(void);
>  
> +#ifdef CONFIG_ACPI
> +
> +enum riscv_irqchip_type {
> +	ACPI_RISCV_IRQCHIP_INTC		= 0x00,
> +	ACPI_RISCV_IRQCHIP_IMSIC	= 0x01,
> +	ACPI_RISCV_IRQCHIP_PLIC		= 0x02,
> +	ACPI_RISCV_IRQCHIP_APLIC	= 0x03,
> +};
> +
> +int riscv_acpi_get_gsi_info(struct fwnode_handle *fwnode, u32 *gsi_base,
> +			    u32 *id, u32 *nr_irqs, u32 *nr_idcs);
> +struct fwnode_handle *riscv_acpi_get_gsi_domain_id(u32 gsi);
> +
> +#else
> +static inline int riscv_acpi_get_gsi_info(struct fwnode_handle *fwnode, u32 *gsi_base,
> +					  u32 *id, u32 *nr_irqs, u32 *nr_idcs)
> +{
> +	return 0;
> +}
> +
> +#endif /* CONFIG_ACPI */
> +
>  #endif /* _ASM_RISCV_IRQ_H */
> diff --git a/drivers/acpi/riscv/init.c b/drivers/acpi/riscv/init.c
> index 5f7571143245..22db97f7a772 100644
> --- a/drivers/acpi/riscv/init.c
> +++ b/drivers/acpi/riscv/init.c
> @@ -6,7 +6,9 @@
>   */
>  
>  #include <linux/acpi.h>
> +#include "init.h"
>  
>  void __init acpi_riscv_init(void)
>  {
> +	riscv_acpi_init_gsi_mapping();
>  }
> diff --git a/drivers/acpi/riscv/init.h b/drivers/acpi/riscv/init.h
> new file mode 100644
> index 000000000000..0b9a07e4031f
> --- /dev/null
> +++ b/drivers/acpi/riscv/init.h
> @@ -0,0 +1,4 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#include <linux/init.h>
> +
> +void __init riscv_acpi_init_gsi_mapping(void);
> diff --git a/drivers/acpi/riscv/irq.c b/drivers/acpi/riscv/irq.c
> index f56e103a501f..0473428e8d1e 100644
> --- a/drivers/acpi/riscv/irq.c
> +++ b/drivers/acpi/riscv/irq.c
> @@ -7,6 +7,21 @@
>  
>  #include <linux/acpi.h>
>  #include <linux/sort.h>
> +#include <linux/irq.h>
> +
> +#include "init.h"
> +
> +struct riscv_ext_intc_list {
> +	acpi_handle handle;
> +	u32 gsi_base;
> +	u32 nr_irqs;
> +	u32 nr_idcs;
> +	u32 id;
> +	u32 type;
> +	struct list_head list;
> +};
> +
> +LIST_HEAD(ext_intc_list);
>  
>  static int irqchip_cmp_func(const void *in0, const void *in1)
>  {
> @@ -30,3 +45,130 @@ void arch_sort_irqchip_probe(struct acpi_probe_entry *ap_head, int nr)
>  		return;
>  	sort(ape, nr, sizeof(*ape), irqchip_cmp_func, NULL);
>  }
> +
> +static void riscv_acpi_update_gsi_handle(u32 gsi_base, acpi_handle handle)
> +{
> +	struct riscv_ext_intc_list *ext_intc_element;
> +	struct list_head *i, *tmp;
> +
> +	list_for_each_safe(i, tmp, &ext_intc_list) {
> +		ext_intc_element = list_entry(i, struct riscv_ext_intc_list, list);
> +		if (gsi_base == ext_intc_element->gsi_base) {
> +			ext_intc_element->handle = handle;
> +			return;
> +		}
> +	}
> +
> +	acpi_handle_err(handle, "failed to find the GSI mapping entry\n");
> +}
> +
> +int riscv_acpi_get_gsi_info(struct fwnode_handle *fwnode, u32 *gsi_base,
> +			    u32 *id, u32 *nr_irqs, u32 *nr_idcs)
> +{
> +	struct riscv_ext_intc_list *ext_intc_element;
> +	struct list_head *i, *tmp;
> +
> +	list_for_each_safe(i, tmp, &ext_intc_list) {
> +		ext_intc_element = list_entry(i, struct riscv_ext_intc_list, list);
> +		if (ext_intc_element->handle == ACPI_HANDLE_FWNODE(fwnode)) {
> +			*gsi_base = ext_intc_element->gsi_base;
> +			*id = ext_intc_element->id;
> +			*nr_irqs = ext_intc_element->nr_irqs;
> +			if (nr_idcs)
> +				*nr_idcs = ext_intc_element->nr_idcs;
> +
> +			return 0;
> +		}
> +	}
> +
> +	return -ENODEV;
> +}
> +
> +struct fwnode_handle *riscv_acpi_get_gsi_domain_id(u32 gsi)
> +{
> +	struct riscv_ext_intc_list *ext_intc_element;
> +	struct acpi_device *adev;
> +	struct list_head *i, *tmp;
> +
> +	list_for_each_safe(i, tmp, &ext_intc_list) {
> +		ext_intc_element = list_entry(i, struct riscv_ext_intc_list, list);
> +		if (gsi >= ext_intc_element->gsi_base &&
> +		    gsi < (ext_intc_element->gsi_base + ext_intc_element->nr_irqs)) {
> +			adev = acpi_fetch_acpi_dev(ext_intc_element->handle);
> +			if (!adev)
> +				return NULL;
> +
> +			return acpi_fwnode_handle(adev);
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static int __init riscv_acpi_register_ext_intc(u32 gsi_base, u32 nr_irqs, u32 nr_idcs,
> +					       u32 id, u32 type)
> +{
> +	struct riscv_ext_intc_list *ext_intc_element;
> +
> +	ext_intc_element = kzalloc(sizeof(*ext_intc_element), GFP_KERNEL);
> +	if (!ext_intc_element)
> +		return -ENOMEM;
> +
> +	ext_intc_element->gsi_base = gsi_base;
> +	ext_intc_element->nr_irqs = nr_irqs;
> +	ext_intc_element->nr_idcs = nr_idcs;
> +	ext_intc_element->id = id;
> +	list_add_tail(&ext_intc_element->list, &ext_intc_list);
> +	return 0;
> +}
> +
> +static acpi_status __init riscv_acpi_create_gsi_map(acpi_handle handle, u32 level,
> +						    void *context, void **return_value)
> +{
> +	acpi_status status;
> +	u64 gbase;
> +
> +	if (!acpi_has_method(handle, "_GSB")) {
> +		acpi_handle_err(handle, "_GSB method not found\n");
> +		return AE_OK;
> +	}
> +
> +	status = acpi_evaluate_integer(handle, "_GSB", NULL, &gbase);
> +	if (ACPI_FAILURE(status)) {
> +		acpi_handle_err(handle, "failed to evaluate _GSB method\n");
> +		return AE_OK;
> +	}
> +
> +	riscv_acpi_update_gsi_handle((u32)gbase, handle);
> +	return AE_OK;
> +}
> +
> +static int __init riscv_acpi_aplic_parse_madt(union acpi_subtable_headers *header,
> +					      const unsigned long end)
> +{
> +	struct acpi_madt_aplic *aplic = (struct acpi_madt_aplic *)header;
> +
> +	return riscv_acpi_register_ext_intc(aplic->gsi_base, aplic->num_sources, aplic->num_idcs,
> +					    aplic->id, ACPI_RISCV_IRQCHIP_APLIC);
> +}
> +
> +static int __init riscv_acpi_plic_parse_madt(union acpi_subtable_headers *header,
> +					     const unsigned long end)
> +{
> +	struct acpi_madt_plic *plic = (struct acpi_madt_plic *)header;
> +
> +	return riscv_acpi_register_ext_intc(plic->gsi_base, plic->num_irqs, 0,
> +					    plic->id, ACPI_RISCV_IRQCHIP_PLIC);
> +}
> +
> +void __init riscv_acpi_init_gsi_mapping(void)
> +{
> +	/* There can be either PLIC or APLIC */
> +	if (acpi_table_parse_madt(ACPI_MADT_TYPE_PLIC, riscv_acpi_plic_parse_madt, 0) > 0) {
> +		acpi_get_devices("RSCV0001", riscv_acpi_create_gsi_map, NULL, NULL);
> +		return;
> +	}
> +
> +	if (acpi_table_parse_madt(ACPI_MADT_TYPE_APLIC, riscv_acpi_aplic_parse_madt, 0) > 0)
> +		acpi_get_devices("RSCV0002", riscv_acpi_create_gsi_map, NULL, NULL);
> +}

I don't know if it is needed in RISC-V - it is a question - but how would you
resolve a GSI mapping before the ACPI intepreter is initialized ?

This model relies on the _GSB method to be called on the interrupt controller
device to discover the GSI range it actually covers, I was wondering how this
works for "devices" (eg components described in static table, eg timers)
that require a GSI mapping before you are able to retrieve the required
information from the namespace devices.

Thanks,
Lorenzo