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

Lorenzo Pieralisi
2024-07-10T10:45:45Z

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@ventanamicro.com>
> ---
> 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