LXR linux/drivers/uio/uio_pci

   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
  31struct uio_pci_generic_dev {
  32        struct uio_info info;
  33        struct pci_dev *pdev;
  34};
  35
  36static inline struct uio_pci_generic_dev *
  37to_uio_pci_generic_dev(struct uio_info *info)
  38{
  39        return container_of(info, struct uio_pci_generic_dev, info);
  40}
  41
  42static int release(struct uio_info *info, struct inode *inode)
  43{
  44        struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
  45
  46        /*
  47         * This driver is insecure when used with devices doing DMA, but some
  48         * people (mis)use it with such devices.
  49         * Let's at least make sure DMA isn't left enabled after the userspace
  50         * driver closes the fd.
  51         * Note that there's a non-zero chance doing this will wedge the device
  52         * at least until reset.
  53         */
  54        pci_clear_master(gdev->pdev);
  55        return 0;
  56}
  57
  58/* Interrupt handler. Read/modify/write the command register to disable
  59 * the interrupt. */
  60static irqreturn_t irqhandler(int irq, struct uio_info *info)
  61{
  62        struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
  63
  64        if (!pci_check_and_mask_intx(gdev->pdev))
  65                return IRQ_NONE;
  66
  67        /* UIO core will signal the user process. */
  68        return IRQ_HANDLED;
  69}
  70
  71static int probe(struct pci_dev *pdev,
  72                           const struct pci_device_id *id)
  73{
  74        struct uio_pci_generic_dev *gdev;
  75        int err;
  76
  77        err = pci_enable_device(pdev);
  78        if (err) {
  79                dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
  80                        __func__, err);
  81                return err;
  82        }
  83
  84        if (pdev->irq && !pci_intx_mask_supported(pdev)) {
  85                err = -ENODEV;
  86                goto err_verify;
  87        }
  88
  89        gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
  90        if (!gdev) {
  91                err = -ENOMEM;
  92                goto err_alloc;
  93        }
  94
  95        gdev->info.name = "uio_pci_generic";
  96        gdev->info.version = DRIVER_VERSION;
  97        gdev->info.release = release;
  98        gdev->pdev = pdev;
  99        if (pdev->irq) {
 100                gdev->info.irq = pdev->irq;
 101                gdev->info.irq_flags = IRQF_SHARED;
 102                gdev->info.handler = irqhandler;
 103        } else {
 104                dev_warn(&pdev->dev, "No IRQ assigned to device: "
 105                         "no support for interrupts?\n");
 106        }
 107
 108        err = uio_register_device(&pdev->dev, &gdev->info);
 109        if (err)
 110                goto err_register;
 111        pci_set_drvdata(pdev, gdev);
 112
 113        return 0;
 114err_register:
 115        kfree(gdev);
 116err_alloc:
 117err_verify:
 118        pci_disable_device(pdev);
 119        return err;
 120}
 121
 122static void remove(struct pci_dev *pdev)
 123{
 124        struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
 125
 126        uio_unregister_device(&gdev->info);
 127        pci_disable_device(pdev);
 128        kfree(gdev);
 129}
 130
 131static struct pci_driver uio_pci_driver = {
 132        .name = "uio_pci_generic",
 133        .id_table = NULL, /* only dynamic id's */
 134        .probe = probe,
 135        .remove = remove,
 136};
 137
 138module_pci_driver(uio_pci_driver);
 139MODULE_VERSION(DRIVER_VERSION);
 140MODULE_LICENSE("GPL v2");
 141MODULE_AUTHOR(DRIVER_AUTHOR);
 142MODULE_DESCRIPTION(DRIVER_DESC);
 143