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From: Sunil V L <sunilvl@ventanamicro.com>
To: linux-arm-kernel@lists.infradead.org,
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	Andrew Jones <ajones@ventanamicro.com>,
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	Marc Zyngier <maz@kernel.org>,
	Atish Kumar Patra <atishp@rivosinc.com>,
	Haibo1 Xu <haibo1.xu@intel.com>,
	=?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= <bjorn@kernel.org>,
	Sunil V L <sunilvl@ventanamicro.com>
Subject: [PATCH v6 02/17] ACPI: scan: Add a weak function to reorder the IRQCHIP probe
Date: Sat,  1 Jun 2024 20:33:56 +0530
Message-Id: <20240601150411.1929783-3-sunilvl@ventanamicro.com>
In-Reply-To: <20240601150411.1929783-1-sunilvl@ventanamicro.com>
References: <20240601150411.1929783-1-sunilvl@ventanamicro.com>
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Unlike OF framework, the irqchip probe using IRQCHIP_ACPI_DECLARE has no
order defined. Depending on the 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 503773707e01..b325b297bf77 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2744,6 +2744,8 @@ 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;
@@ -2752,6 +2754,7 @@ 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 28c3fb2bef0d..ab3f2880d209 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1332,6 +1332,8 @@ 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	\
-- 
2.40.1