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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>,
	=?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= <bjorn@kernel.org>,
	Marc Zyngier <maz@kernel.org>,
	Sunil V L <sunilvl@ventanamicro.com>
Subject: [RFC PATCH v3 04/17] ACPI: Add fw_devlink support for ACPI fwnode for IRQ dependency
Date: Tue, 19 Dec 2023 23:15:13 +0530
Message-Id: <20231219174526.2235150-5-sunilvl@ventanamicro.com>
In-Reply-To: <20231219174526.2235150-1-sunilvl@ventanamicro.com>
References: <20231219174526.2235150-1-sunilvl@ventanamicro.com>
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Currently ACPI doesn't support fw_devlink infrastructure which helps in
ordering the driver probe in the order of dependencies. One of the
dependency between devices in ACPI is GSI interrupt source. This
interrupt source can be another device and mentioned as part of
ResourceSource in the ASL. Or it can be indirectly determined by the GSI
mapping. In either way, adding the link for this dependency avoids
modifying all drivers to handle EPROBE_DEFER. So, add this new interface
into ACPI's fwnode handlers.

Currently, this is necessary for RISC-V architecture. So, kept the
interface functional only for RISC-V. But in future other architectures
also can enable this functionality or can be made common.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/acpi/irq.c      | 18 ++++++++++++++++++
 drivers/acpi/property.c | 20 ++++++++++++++++++++
 include/linux/acpi.h    |  9 +++++++++
 3 files changed, 47 insertions(+)

diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
index 1687483ff319..b3409e2e2041 100644
--- a/drivers/acpi/irq.c
+++ b/drivers/acpi/irq.c
@@ -354,3 +354,21 @@ struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags,
 					   host_data);
 }
 EXPORT_SYMBOL_GPL(acpi_irq_create_hierarchy);
+
+int acpi_get_gsi_parent_fwnode(acpi_handle handle,
+			       unsigned int index,
+			       struct fwnode_handle **parent)
+{
+	struct irq_fwspec fwspec;
+	unsigned long flags;
+	int rc;
+
+	fwspec.fwnode = NULL;
+	rc = acpi_irq_parse_one(handle, index, &fwspec, &flags);
+	if (rc || !fwspec.fwnode)
+		return 0;
+
+	*parent = fwspec.fwnode;
+	return 1;
+}
+EXPORT_SYMBOL_GPL(acpi_get_gsi_parent_fwnode);
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 413e4fcadcaf..88769acb13d4 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1572,6 +1572,25 @@ static int acpi_fwnode_irq_get(const struct fwnode_handle *fwnode,
 	return res.start;
 }
 
+static int acpi_fwnode_add_links(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent_fwnode;
+	unsigned int i;
+
+	/* This is needed primarily for RISC-V. Other architectures can
+	 * be enabled or made this generic if required.
+	 */
+	if (!IS_ENABLED(CONFIG_RISCV))
+		return 0;
+
+	for (i = 0;
+		   acpi_get_gsi_parent_fwnode(ACPI_HANDLE_FWNODE(fwnode), i, &parent_fwnode);
+		   i++)
+		fwnode_link_add(fwnode, parent_fwnode);
+
+	return 0;
+}
+
 #define DECLARE_ACPI_FWNODE_OPS(ops) \
 	const struct fwnode_operations ops = {				\
 		.device_is_available = acpi_fwnode_device_is_available, \
@@ -1597,6 +1616,7 @@ static int acpi_fwnode_irq_get(const struct fwnode_handle *fwnode,
 		.graph_get_port_parent = acpi_fwnode_get_parent,	\
 		.graph_parse_endpoint = acpi_fwnode_graph_parse_endpoint, \
 		.irq_get = acpi_fwnode_irq_get,				\
+		.add_links = acpi_fwnode_add_links,			\
 	};								\
 	EXPORT_SYMBOL_GPL(ops)
 
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index afd94c9b8b8a..e9a9659314f2 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1463,12 +1463,21 @@ static inline int acpi_parse_spcr(bool enable_earlycon, bool enable_console)
 
 #if IS_ENABLED(CONFIG_ACPI_GENERIC_GSI)
 int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res);
+int acpi_get_gsi_parent_fwnode(acpi_handle handle, unsigned int index,
+			       struct fwnode_handle **parent);
 #else
 static inline
 int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
 {
 	return -EINVAL;
 }
+
+static inline
+int acpi_get_gsi_parent_fwnode(acpi_handle handle, unsigned int index,
+			       struct fwnode_handle **parent)
+{
+	return 0;
+}
 #endif
 
 #ifdef CONFIG_ACPI_LPIT
-- 
2.39.2