linux-kernel - [RFC PATCH v3 07/17] ACPI: scan.c: Add weak arch specific function to reorder the IRQCHIP probe

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Message-Id: <20231219174526.2235150-8-sunilvl@ventanamicro.com>
Date: Tue, 19 Dec 2023 23:15:16 +0530
From: Sunil V L <sunilvl@...tanamicro.com>
To: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-acpi@...r.kernel.org,
	linux-pci@...r.kernel.org
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Anup Patel <anup@...infault.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Haibo Xu <haibo1.xu@...el.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Andrew Jones <ajones@...tanamicro.com>,
	Björn Töpel <bjorn@...nel.org>,
	Marc Zyngier <maz@...nel.org>,
	Sunil V L <sunilvl@...tanamicro.com>
Subject: [RFC PATCH v3 07/17] ACPI: scan.c: Add weak arch specific function to reorder the IRQCHIP probe

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@...tanamicro.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 e9a9659314f2..ae045e14126b 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