drivers/uio/uio_pci_generic.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* uio_pci_generic - generic UIO driver for PCI 2.3 devices
   3  *
   4  * Copyright (C) 2009 Red Hat, Inc.
   5  * Author: Michael S. Tsirkin <mst@redhat.com>
   6  *
   7  * Since the driver does not declare any device ids, you must allocate
   8  * id and bind the device to the driver yourself.  For example:
   9  *
  10  * # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
  11  * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
  12  * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
  13  * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
  14  * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
  15  *
  16  * Driver won't bind to devices which do not support the Interrupt Disable Bit
  17  * in the command register. All devices compliant to PCI 2.3 (circa 2002) and
  18  * all compliant PCI Express devices should support this bit.
  19  */
  20
  21 #include <linux/device.h>
  22 #include <linux/module.h>
  23 #include <linux/pci.h>
  24 #include <linux/slab.h>
  25 #include <linux/uio_driver.h>
  26
  27 #define DRIVER_VERSION  "0.01.0"
  28 #define DRIVER_AUTHOR   "Michael S. Tsirkin <mst@redhat.com>"
  29 #define DRIVER_DESC     "Generic UIO driver for PCI 2.3 devices"
  30
  31 struct uio_pci_generic_dev {
  32         struct uio_info info;
  33         struct pci_dev *pdev;
  34 };
  35
  36 static inline struct uio_pci_generic_dev *
  37 to_uio_pci_generic_dev(struct uio_info *info)
  38 {
  39         return container_of(info, struct uio_pci_generic_dev, info);
  40 }
  41
  42 /* Interrupt handler. Read/modify/write the command register to disable
  43  * the interrupt. */
  44 static irqreturn_t irqhandler(int irq, struct uio_info *info)
  45 {
  46         struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
  47
  48         if (!pci_check_and_mask_intx(gdev->pdev))
  49                 return IRQ_NONE;
  50
  51         /* UIO core will signal the user process. */
  52         return IRQ_HANDLED;
  53 }
  54
  55 static int probe(struct pci_dev *pdev,
  56                            const struct pci_device_id *id)
  57 {
  58         struct uio_pci_generic_dev *gdev;
  59         int err;
  60
  61         err = pci_enable_device(pdev);
  62         if (err) {
  63                 dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
  64                         __func__, err);
  65                 return err;
  66         }
  67
  68         if (pdev->irq && !pci_intx_mask_supported(pdev)) {
  69                 err = -ENODEV;
  70                 goto err_verify;
  71         }
  72
  73         gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
  74         if (!gdev) {
  75                 err = -ENOMEM;
  76                 goto err_alloc;
  77         }
  78
  79         gdev->info.name = "uio_pci_generic";
  80         gdev->info.version = DRIVER_VERSION;
  81         gdev->pdev = pdev;
  82         if (pdev->irq) {
  83                 gdev->info.irq = pdev->irq;
  84                 gdev->info.irq_flags = IRQF_SHARED;
  85                 gdev->info.handler = irqhandler;
  86         } else {
  87                 dev_warn(&pdev->dev, "No IRQ assigned to device: "
  88                          "no support for interrupts?\n");
  89         }
  90
  91         err = uio_register_device(&pdev->dev, &gdev->info);
  92         if (err)
  93                 goto err_register;
  94         pci_set_drvdata(pdev, gdev);
  95
  96         return 0;
  97 err_register:
  98         kfree(gdev);
  99 err_alloc:
 100 err_verify:
 101         pci_disable_device(pdev);
 102         return err;
 103 }
 104
 105 static void remove(struct pci_dev *pdev)
 106 {
 107         struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
 108
 109         uio_unregister_device(&gdev->info);
 110         pci_disable_device(pdev);
 111         kfree(gdev);
 112 }
 113
 114 static struct pci_driver uio_pci_driver = {
 115         .name = "uio_pci_generic",
 116         .id_table = NULL, /* only dynamic id's */
 117         .probe = probe,
 118         .remove = remove,
 119 };
 120
 121 module_pci_driver(uio_pci_driver);
 122 MODULE_VERSION(DRIVER_VERSION);
 123 MODULE_LICENSE("GPL v2");
 124 MODULE_AUTHOR(DRIVER_AUTHOR);
 125 MODULE_DESCRIPTION(DRIVER_DESC);