[RFC PATCH v2 09/21] ACPI: scan.c: Add weak arch specific function to reorder the IRQCHIP probe

Sunil V L
2023-10-25T20:25:09Z

Unlike OF framework, the irqchip probe using IRQCHIP_ACPI_DECLARE has no
order defined. Depending on the driver Makefile is not a good idea. So,
usually it is worked around by mandating only root interrupt controller
probed using IRQCHIP_ACPI_DECLARE and other interrupt controllers are
probed via cascade mechanism.

However, this is also not a clean solution because if there are multiple
root controllers (ex: RINTC in RISC-V which is per CPU) which need to be
probed first, then the cascade will happen for every root controller.
So, introduce a architecture specific weak function to order the probing
of the interrupt controllers which can be implemented by different
architectures as per their interrupt controller hierarchy.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
drivers/acpi/scan.c | 3 +++
include/linux/acpi.h | 2 ++
2 files changed, 5 insertions(+)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 691d4b7686ee..87f4baebd497 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2685,6 +2685,8 @@ static int __init acpi_match_madt(union acpi_subtable_headers *header,
return 0;
}

+void __weak arch_sort_irqchip_probe(struct acpi_probe_entry *ap_head, int nr) { }
+
int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
{
int count = 0;
@@ -2693,6 +2695,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
return 0;

mutex_lock(&acpi_probe_mutex);
+ arch_sort_irqchip_probe(ap_head, nr);
for (ape = ap_head; nr; ape++, nr--) {
if (ACPI_COMPARE_NAMESEG(ACPI_SIG_MADT, ape->id)) {
acpi_probe_count = 0;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index afd94c9b8b8a..4ad256a0039c 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1338,6 +1338,8 @@ struct acpi_probe_entry {
kernel_ulong_t driver_data;
};

+void arch_sort_irqchip_probe(struct acpi_probe_entry *ap_head, int nr);
+
#define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, \
valid, data, fn) \
static const struct acpi_probe_entry __acpi_probe_##name \
--
2.39.2