linux-kernel - [PATCH v2 17/19] PCI: of_property: Add interrupt-controller property in PCI device nodes

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Message-ID: <20240527161450.326615-18-herve.codina@bootlin.com>
Date: Mon, 27 May 2024 18:14:44 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Simon Horman <horms@...nel.org>,
	Sai Krishna Gajula <saikrishnag@...vell.com>,
	Herve Codina <herve.codina@...tlin.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Lee Jones <lee@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	UNGLinuxDriver@...rochip.com,
	Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Saravana Kannan <saravanak@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Lars Povlsen <lars.povlsen@...rochip.com>,
	Steen Hegelund <Steen.Hegelund@...rochip.com>,
	Daniel Machon <daniel.machon@...rochip.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Allan Nielsen <allan.nielsen@...rochip.com>,
	Steen Hegelund <steen.hegelund@...rochip.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: [PATCH v2 17/19] PCI: of_property: Add interrupt-controller property in PCI device nodes

PCI devices and bridges DT nodes created during the PCI scan are created
with the interrupt-map property set to handle interrupts.

In order to set this interrupt-map property at a specific level, a
phandle to the parent interrupt controller is needed. On systems that
are not fully described by a device-tree, the parent interrupt
controller may be unavailable (i.e. not described by the device-tree).

As mentioned in the [1], avoiding the use of the interrupt-map property
and considering a PCI device as an interrupt controller itself avoid the
use of a parent interrupt phandle.

In that case, the PCI device itself as an interrupt controller is
responsible for routing the interrupts described in the device-tree
world (DT overlay) to the PCI interrupts.

Add the 'interrupt-controller' property in the PCI device DT node.

[1]: https://lore.kernel.org/lkml/CAL_Jsq+je7+9ATR=B6jXHjEJHjn24vQFs4Tvi9=vhDeK9n42Aw@mail.gmail.com/

Signed-off-by: Herve Codina <herve.codina@...tlin.com>
---
 drivers/pci/of_property.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 03539e505372..5a0b98e69795 100644
--- a/drivers/pci/of_property.c
+++ b/drivers/pci/of_property.c
@@ -183,6 +183,26 @@ static int of_pci_prop_interrupts(struct pci_dev *pdev,
 	return of_changeset_add_prop_u32(ocs, np, "interrupts", (u32)pin);
 }
 
+static int of_pci_prop_intr_ctrl(struct pci_dev *pdev, struct of_changeset *ocs,
+				 struct device_node *np)
+{
+	int ret;
+	u8 pin;
+
+	ret = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
+	if (ret != 0)
+		return ret;
+
+	if (!pin)
+		return 0;
+
+	ret = of_changeset_add_prop_u32(ocs, np, "#interrupt-cells", 1);
+	if (ret)
+		return ret;
+
+	return of_changeset_add_prop_bool(ocs, np, "interrupt-controller");
+}
+
 static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
 				struct device_node *np)
 {
@@ -336,6 +356,10 @@ int of_pci_add_properties(struct pci_dev *pdev, struct of_changeset *ocs,
 		ret = of_pci_prop_intr_map(pdev, ocs, np);
 		if (ret)
 			return ret;
+	} else {
+		ret = of_pci_prop_intr_ctrl(pdev, ocs, np);
+		if (ret)
+			return ret;
 	}
 
 	ret = of_pci_prop_ranges(pdev, ocs, np);
-- 
2.45.0