root/drivers/uio/uio_pci_generic.c

DEFINITIONS

1. to_uio_pci_generic_dev
2. release
3. irqhandler
4. probe
5. remove

   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 = 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;
 114 err_register:
 115         kfree(gdev);
 116 err_alloc:
 117 err_verify:
 118         pci_disable_device(pdev);
 119         return err;
 120 }
 121 
 122 static 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 
 131 static 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 
 138 module_pci_driver(uio_pci_driver);
 139 MODULE_VERSION(DRIVER_VERSION);
 140 MODULE_LICENSE("GPL v2");
 141 MODULE_AUTHOR(DRIVER_AUTHOR);
 142 MODULE_DESCRIPTION(DRIVER_DESC);