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 static 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. */
  60 static 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
  71 static 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 -ENOMEM;
  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) {
  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
 107 static struct pci_driver uio_pci_driver = {
 108         .name = "uio_pci_generic",
 109         .id_table = NULL, /* only dynamic id's */
 110         .probe = probe,
 111 };
 112
 113 module_pci_driver(uio_pci_driver);
 114 MODULE_VERSION(DRIVER_VERSION);
 115 MODULE_LICENSE("GPL v2");
 116 MODULE_AUTHOR(DRIVER_AUTHOR);
 117 MODULE_DESCRIPTION(DRIVER_DESC);