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

From: Sunil V L <sunilvl@ventanamicro.com>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org
Cc: "Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Len Brown" <lenb@kernel.org>, "Anup Patel" <anup@brainfault.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Haibo Xu" <haibo1.xu@intel.com>,
	"Conor Dooley" <conor.dooley@microchip.com>,
	"Andrew Jones" <ajones@ventanamicro.com>,
	"Björn Töpel" <bjorn@kernel.org>, "Marc Zyngier" <maz@kernel.org>,
	"Sunil V L" <sunilvl@ventanamicro.com>
Subject: [RFC PATCH v3 07/17] ACPI: scan.c: Add weak arch specific function to reorder the IRQCHIP probe
Date: Tue, 19 Dec 2023 23:15:16 +0530	[thread overview]
Message-ID: <20231219174526.2235150-8-sunilvl@ventanamicro.com> (raw)
In-Reply-To: <20231219174526.2235150-1-sunilvl@ventanamicro.com>

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 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

