linux-kernel - [PATCH] PCI: mvebu: Use devm_request_irq() for registering interrupt handler

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Date:   Tue, 24 May 2022 14:28:17 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] PCI: mvebu: Use devm_request_irq() for registering interrupt handler

Same as in commit a3b69dd0ad62 ("Revert "PCI: aardvark: Rewrite IRQ code to
chained IRQ handler"") for pci-aardvark driver, use devm_request_irq()
instead of chained IRQ handler in pci-mvebu.c driver.

This change fixes affinity support and allows to pin interrupts from
different PCIe controllers to different CPU cores.

Fixes: ec075262648f ("PCI: mvebu: Implement support for legacy INTx interrupts")
Signed-off-by: Pali Rohár <pali@...nel.org>
---
Hello Bjorn! This is basically same issue as for pci-aardvark.c:
https://lore.kernel.org/linux-pci/20220515125815.30157-1-pali@kernel.org/#t

I tested this patch with pci=nomsi in cmdline (to force kernel to use
legacy intx instead of MSI) on A385 and checked that I can set affinity
via /proc/irq/XX/smp_affinity file for every mvebu pcie controller to
different CPU and legacy interrupts from different cards/controllers
were handled by different CPUs.

I think that this is important on Armada XP platforms which have many
independent PCIe controllers (IIRC up to 10) and many cores (up to 4).
---
 drivers/pci/controller/pci-mvebu.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 8f76d4bda356..de67ea39fea5 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -1017,16 +1017,13 @@ static int mvebu_pcie_init_irq_domain(struct mvebu_pcie_port *port)
 	return 0;
 }
 
-static void mvebu_pcie_irq_handler(struct irq_desc *desc)
+static irqreturn_t mvebu_pcie_irq_handler(int irq, void *arg)
 {
-	struct mvebu_pcie_port *port = irq_desc_get_handler_data(desc);
-	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct mvebu_pcie_port *port = arg;
 	struct device *dev = &port->pcie->pdev->dev;
 	u32 cause, unmask, status;
 	int i;
 
-	chained_irq_enter(chip, desc);
-
 	cause = mvebu_readl(port, PCIE_INT_CAUSE_OFF);
 	unmask = mvebu_readl(port, PCIE_INT_UNMASK_OFF);
 	status = cause & unmask;
@@ -1040,7 +1037,7 @@ static void mvebu_pcie_irq_handler(struct irq_desc *desc)
 			dev_err_ratelimited(dev, "unexpected INT%c IRQ\n", (char)i+'A');
 	}
 
-	chained_irq_exit(chip, desc);
+	return status ? IRQ_HANDLED : IRQ_NONE;
 }
 
 static int mvebu_pcie_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
@@ -1490,9 +1487,20 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
 				mvebu_pcie_powerdown(port);
 				continue;
 			}
-			irq_set_chained_handler_and_data(irq,
-							 mvebu_pcie_irq_handler,
-							 port);
+
+			ret = devm_request_irq(dev, irq, mvebu_pcie_irq_handler,
+					       IRQF_SHARED | IRQF_NO_THREAD,
+					       port->name, port);
+			if (ret) {
+				dev_err(dev, "%s: cannot register interrupt handler: %d\n",
+					port->name, ret);
+				irq_domain_remove(port->intx_irq_domain);
+				pci_bridge_emul_cleanup(&port->bridge);
+				devm_iounmap(dev, port->base);
+				port->base = NULL;
+				mvebu_pcie_powerdown(port);
+				continue;
+			}
 		}
 
 		/*
@@ -1599,7 +1607,6 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
 
 	for (i = 0; i < pcie->nports; i++) {
 		struct mvebu_pcie_port *port = &pcie->ports[i];
-		int irq = port->intx_irq;
 
 		if (!port->base)
 			continue;
@@ -1615,9 +1622,6 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
 		/* Clear all interrupt causes. */
 		mvebu_writel(port, ~PCIE_INT_ALL_MASK, PCIE_INT_CAUSE_OFF);
 
-		if (irq > 0)
-			irq_set_chained_handler_and_data(irq, NULL, NULL);
-
 		/* Remove IRQ domains. */
 		if (port->intx_irq_domain)
 			irq_domain_remove(port->intx_irq_domain);
-- 
2.20.1