linux/drivers/uio/uio_pci_generic.c
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   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        \xC2\xA0* people (mis)use it with such devices.
  49        \xC2\xA0* Let's at least make sure DMA isn't left enabled after the userspace
  50        \xC2\xA0* driver closes the fd.
  51        \xC2\xA0* Note that there's a non-zero chance doing this will wedge the device
  52        \xC2\xA0* 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 = pcim_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                return -ENODEV;
  86
  87        gdev = devm_kzalloc(&pdev->dev, sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
  88        if (!gdev)
  89                return -ENOMEM;
  90
  91        gdev->info.name = "uio_pci_generic";
  92        gdev->info.version = DRIVER_VERSION;
  93        gdev->info.release = release;
  94        gdev->pdev = pdev;
  95        if (pdev->irq && (pdev->irq != IRQ_NOTCONNECTED)) {
  96                gdev->info.irq = pdev->irq;
  97                gdev->info.irq_flags = IRQF_SHARED;
  98                gdev->info.handler = irqhandler;
  99        } else {
 100                dev_warn(&pdev->dev, "No IRQ assigned to device: "
 101                         "no support for interrupts?\n");
 102        }
 103
 104        return devm_uio_register_device(&pdev->dev, &gdev->info);
 105}
 106
 107static struct pci_driver uio_pci_driver = {
 108        .name = "uio_pci_generic",
 109        .id_table = NULL, /* only dynamic id's */
 110        .probe = probe,
 111};
 112
 113module_pci_driver(uio_pci_driver);
 114MODULE_VERSION(DRIVER_VERSION);
 115MODULE_LICENSE("GPL v2");
 116MODULE_AUTHOR(DRIVER_AUTHOR);
 117MODULE_DESCRIPTION(DRIVER_DESC);
 118