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         struct uio_mem *uiomem;
  76         int err;
  77         int i;
  78
  79         err = pcim_enable_device(pdev);
  80         if (err) {
  81                 dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
  82                         __func__, err);
  83                 return err;
  84         }
  85
  86         if (pdev->irq && !pci_intx_mask_supported(pdev))
  87                 return -ENODEV;
  88
  89         gdev = devm_kzalloc(&pdev->dev, sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
  90         if (!gdev)
  91                 return -ENOMEM;
  92
  93         gdev->info.name = "uio_pci_generic";
  94         gdev->info.version = DRIVER_VERSION;
  95         gdev->info.release = release;
  96         gdev->pdev = pdev;
  97         if (pdev->irq && (pdev->irq != IRQ_NOTCONNECTED)) {
  98                 gdev->info.irq = pdev->irq;
  99                 gdev->info.irq_flags = IRQF_SHARED;
 100                 gdev->info.handler = irqhandler;
 101         } else {
 102                 dev_warn(&pdev->dev, "No IRQ assigned to device: "
 103                          "no support for interrupts?\n");
 104         }
 105
 106         uiomem = &gdev->info.mem[0];
 107         for (i = 0; i < MAX_UIO_MAPS; ++i) {
 108                 struct resource *r = &pdev->resource[i];
 109
 110                 if (r->flags != (IORESOURCE_SIZEALIGN | IORESOURCE_MEM))
 111                         continue;
 112
 113                 if (uiomem >= &gdev->info.mem[MAX_UIO_MAPS]) {
 114                         dev_warn(
 115                                 &pdev->dev,
 116                                 "device has more than " __stringify(
 117                                         MAX_UIO_MAPS) " I/O memory resources.\n");
 118                         break;
 119                 }
 120
 121                 uiomem->memtype = UIO_MEM_PHYS;
 122                 uiomem->addr = r->start & PAGE_MASK;
 123                 uiomem->offs = r->start & ~PAGE_MASK;
 124                 uiomem->size =
 125                         (uiomem->offs + resource_size(r) + PAGE_SIZE - 1) &
 126                         PAGE_MASK;
 127                 uiomem->name = r->name;
 128                 ++uiomem;
 129         }
 130
 131         while (uiomem < &gdev->info.mem[MAX_UIO_MAPS]) {
 132                 uiomem->size = 0;
 133                 ++uiomem;
 134         }
 135
 136         return devm_uio_register_device(&pdev->dev, &gdev->info);
 137 }
 138
 139 static struct pci_driver uio_pci_driver = {
 140         .name = "uio_pci_generic",
 141         .id_table = NULL, /* only dynamic id's */
 142         .probe = probe,
 143 };
 144
 145 module_pci_driver(uio_pci_driver);
 146 MODULE_VERSION(DRIVER_VERSION);
 147 MODULE_LICENSE("GPL v2");
 148 MODULE_AUTHOR(DRIVER_AUTHOR);
 149 MODULE_DESCRIPTION(DRIVER_DESC);