drivers/pci/irq.c

   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/device.h>
  10 #include <linux/kernel.h>
  11 #include <linux/export.h>
  12 #include <linux/pci.h>
  13
  14 /**
  15  * pci_request_irq - allocate an interrupt line for a PCI device
  16  * @dev:        PCI device to operate on
  17  * @nr:         device-relative interrupt vector index (0-based).
  18  * @handler:    Function to be called when the IRQ occurs.
  19  *              Primary handler for threaded interrupts.
  20  *              If NULL and thread_fn != NULL the default primary handler is
  21  *              installed.
  22  * @thread_fn:  Function called from the IRQ handler thread
  23  *              If NULL, no IRQ thread is created
  24  * @dev_id:     Cookie passed back to the handler function
  25  * @fmt:        Printf-like format string naming the handler
  26  *
  27  * This call allocates interrupt resources and enables the interrupt line and
  28  * IRQ handling. From the point this call is made @handler and @thread_fn may
  29  * be invoked.  All interrupts requested using this function might be shared.
  30  *
  31  * @dev_id must not be NULL and must be globally unique.
  32  */
  33 int pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler,
  34                 irq_handler_t thread_fn, void *dev_id, const char *fmt, ...)
  35 {
  36         va_list ap;
  37         int ret;
  38         char *devname;
  39         unsigned long irqflags = IRQF_SHARED;
  40
  41         if (!handler)
  42                 irqflags |= IRQF_ONESHOT;
  43
  44         va_start(ap, fmt);
  45         devname = kvasprintf(GFP_KERNEL, fmt, ap);
  46         va_end(ap);
  47
  48         ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn,
  49                                    irqflags, devname, dev_id);
  50         if (ret)
  51                 kfree(devname);
  52         return ret;
  53 }
  54 EXPORT_SYMBOL(pci_request_irq);
  55
  56 /**
  57  * pci_free_irq - free an interrupt allocated with pci_request_irq
  58  * @dev:        PCI device to operate on
  59  * @nr:         device-relative interrupt vector index (0-based).
  60  * @dev_id:     Device identity to free
  61  *
  62  * Remove an interrupt handler. The handler is removed and if the interrupt
  63  * line is no longer in use by any driver it is disabled.  The caller must
  64  * ensure the interrupt is disabled on the device before calling this function.
  65  * The function does not return until any executing interrupts for this IRQ
  66  * have completed.
  67  *
  68  * This function must not be called from interrupt context.
  69  */
  70 void pci_free_irq(struct pci_dev *dev, unsigned int nr, void *dev_id)
  71 {
  72         kfree(free_irq(pci_irq_vector(dev, nr), dev_id));
  73 }
  74 EXPORT_SYMBOL(pci_free_irq);