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        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
 139static struct pci_driver uio_pci_driver = {
 140        .name = "uio_pci_generic",
 141        .id_table = NULL, /* only dynamic id's */
 142        .probe = probe,
 143};
 144
 145module_pci_driver(uio_pci_driver);
 146MODULE_VERSION(DRIVER_VERSION);
 147MODULE_LICENSE("GPL v2");
 148MODULE_AUTHOR(DRIVER_AUTHOR);
 149MODULE_DESCRIPTION(DRIVER_DESC);
 150