drivers/pci/irq.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * PCI IRQ handling code
0004  *
0005  * Copyright (c) 2008 James Bottomley <James.Bottomley@HansenPartnership.com>
0006  * Copyright (C) 2017 Christoph Hellwig.
0007  */
0008
0009 #include <linux/device.h>
0010 #include <linux/kernel.h>
0011 #include <linux/export.h>
0012 #include <linux/pci.h>
0013
0014 /**
0015  * pci_request_irq - allocate an interrupt line for a PCI device
0016  * @dev:    PCI device to operate on
0017  * @nr:     device-relative interrupt vector index (0-based).
0018  * @handler:    Function to be called when the IRQ occurs.
0019  *      Primary handler for threaded interrupts.
0020  *      If NULL and thread_fn != NULL the default primary handler is
0021  *      installed.
0022  * @thread_fn:  Function called from the IRQ handler thread
0023  *      If NULL, no IRQ thread is created
0024  * @dev_id: Cookie passed back to the handler function
0025  * @fmt:    Printf-like format string naming the handler
0026  *
0027  * This call allocates interrupt resources and enables the interrupt line and
0028  * IRQ handling. From the point this call is made @handler and @thread_fn may
0029  * be invoked.  All interrupts requested using this function might be shared.
0030  *
0031  * @dev_id must not be NULL and must be globally unique.
0032  */
0033 int pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler,
0034         irq_handler_t thread_fn, void *dev_id, const char *fmt, ...)
0035 {
0036     va_list ap;
0037     int ret;
0038     char *devname;
0039     unsigned long irqflags = IRQF_SHARED;
0040
0041     if (!handler)
0042         irqflags |= IRQF_ONESHOT;
0043
0044     va_start(ap, fmt);
0045     devname = kvasprintf(GFP_KERNEL, fmt, ap);
0046     va_end(ap);
0047
0048     ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn,
0049                    irqflags, devname, dev_id);
0050     if (ret)
0051         kfree(devname);
0052     return ret;
0053 }
0054 EXPORT_SYMBOL(pci_request_irq);
0055
0056 /**
0057  * pci_free_irq - free an interrupt allocated with pci_request_irq
0058  * @dev:    PCI device to operate on
0059  * @nr:     device-relative interrupt vector index (0-based).
0060  * @dev_id: Device identity to free
0061  *
0062  * Remove an interrupt handler. The handler is removed and if the interrupt
0063  * line is no longer in use by any driver it is disabled.  The caller must
0064  * ensure the interrupt is disabled on the device before calling this function.
0065  * The function does not return until any executing interrupts for this IRQ
0066  * have completed.
0067  *
0068  * This function must not be called from interrupt context.
0069  */
0070 void pci_free_irq(struct pci_dev *dev, unsigned int nr, void *dev_id)
0071 {
0072     kfree(free_irq(pci_irq_vector(dev, nr), dev_id));
0073 }
0074 EXPORT_SYMBOL(pci_free_irq);