xref: /openbmc/linux/drivers/pci/irq.c (revision e639c869)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * PCI IRQ handling code
4  *
5  * Copyright (c) 2008 James Bottomley <James.Bottomley@HansenPartnership.com>
6  * Copyright (C) 2017 Christoph Hellwig.
7  */
8 
9 #include <linux/acpi.h>
10 #include <linux/device.h>
11 #include <linux/kernel.h>
12 #include <linux/export.h>
13 #include <linux/pci.h>
14 
15 static void pci_note_irq_problem(struct pci_dev *pdev, const char *reason)
16 {
17 	struct pci_dev *parent = to_pci_dev(pdev->dev.parent);
18 
19 	dev_err(&pdev->dev,
20 		"Potentially misrouted IRQ (Bridge %s %04x:%04x)\n",
21 		dev_name(&parent->dev), parent->vendor, parent->device);
22 	dev_err(&pdev->dev, "%s\n", reason);
23 	dev_err(&pdev->dev, "Please report to linux-kernel@vger.kernel.org\n");
24 	WARN_ON(1);
25 }
26 
27 /**
28  * pci_lost_interrupt - reports a lost PCI interrupt
29  * @pdev:	device whose interrupt is lost
30  *
31  * The primary function of this routine is to report a lost interrupt
32  * in a standard way which users can recognise (instead of blaming the
33  * driver).
34  *
35  * Returns:
36  * a suggestion for fixing it (although the driver is not required to
37  * act on this).
38  */
39 enum pci_lost_interrupt_reason pci_lost_interrupt(struct pci_dev *pdev)
40 {
41 	if (pdev->msi_enabled || pdev->msix_enabled) {
42 		enum pci_lost_interrupt_reason ret;
43 
44 		if (pdev->msix_enabled) {
45 			pci_note_irq_problem(pdev, "MSIX routing failure");
46 			ret = PCI_LOST_IRQ_DISABLE_MSIX;
47 		} else {
48 			pci_note_irq_problem(pdev, "MSI routing failure");
49 			ret = PCI_LOST_IRQ_DISABLE_MSI;
50 		}
51 		return ret;
52 	}
53 #ifdef CONFIG_ACPI
54 	if (!(acpi_disabled || acpi_noirq)) {
55 		pci_note_irq_problem(pdev, "Potential ACPI misrouting please reboot with acpi=noirq");
56 		/* currently no way to fix acpi on the fly */
57 		return PCI_LOST_IRQ_DISABLE_ACPI;
58 	}
59 #endif
60 	pci_note_irq_problem(pdev, "unknown cause (not MSI or ACPI)");
61 	return PCI_LOST_IRQ_NO_INFORMATION;
62 }
63 EXPORT_SYMBOL(pci_lost_interrupt);
64 
65 /**
66  * pci_request_irq - allocate an interrupt line for a PCI device
67  * @dev:	PCI device to operate on
68  * @nr:		device-relative interrupt vector index (0-based).
69  * @handler:	Function to be called when the IRQ occurs.
70  *		Primary handler for threaded interrupts.
71  *		If NULL and thread_fn != NULL the default primary handler is
72  *		installed.
73  * @thread_fn:	Function called from the IRQ handler thread
74  *		If NULL, no IRQ thread is created
75  * @dev_id:	Cookie passed back to the handler function
76  * @fmt:	Printf-like format string naming the handler
77  *
78  * This call allocates interrupt resources and enables the interrupt line and
79  * IRQ handling. From the point this call is made @handler and @thread_fn may
80  * be invoked.  All interrupts requested using this function might be shared.
81  *
82  * @dev_id must not be NULL and must be globally unique.
83  */
84 int pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler,
85 		irq_handler_t thread_fn, void *dev_id, const char *fmt, ...)
86 {
87 	va_list ap;
88 	int ret;
89 	char *devname;
90 
91 	va_start(ap, fmt);
92 	devname = kvasprintf(GFP_KERNEL, fmt, ap);
93 	va_end(ap);
94 
95 	ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn,
96 			IRQF_SHARED, devname, dev_id);
97 	if (ret)
98 		kfree(devname);
99 	return ret;
100 }
101 EXPORT_SYMBOL(pci_request_irq);
102 
103 /**
104  * pci_free_irq - free an interrupt allocated with pci_request_irq
105  * @dev:	PCI device to operate on
106  * @nr:		device-relative interrupt vector index (0-based).
107  * @dev_id:	Device identity to free
108  *
109  * Remove an interrupt handler. The handler is removed and if the interrupt
110  * line is no longer in use by any driver it is disabled.  The caller must
111  * ensure the interrupt is disabled on the device before calling this function.
112  * The function does not return until any executing interrupts for this IRQ
113  * have completed.
114  *
115  * This function must not be called from interrupt context.
116  */
117 void pci_free_irq(struct pci_dev *dev, unsigned int nr, void *dev_id)
118 {
119 	kfree(free_irq(pci_irq_vector(dev, nr), dev_id));
120 }
121 EXPORT_SYMBOL(pci_free_irq);
122