uio_pci_generic.c

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/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
 *
 * Copyright (C) 2009 Red Hat, Inc.
 * Author: Michael S. Tsirkin <[email protected]>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.
 *
 * Since the driver does not declare any device ids, you must allocate
 * id and bind the device to the driver yourself.  For example:
 *
 * # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
 * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
 * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
 *
 * Driver won't bind to devices which do not support the Interrupt Disable Bit
 * in the command register. All devices compliant to PCI 2.3 (circa 2002) and
 * all compliant PCI Express devices should support this bit.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/uio_driver.h>

#define DRIVER_VERSION  "0.01.0"
#define DRIVER_AUTHOR   "Michael S. Tsirkin <[email protected]>"
#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"

struct uio_pci_generic_dev {
    struct uio_info info;
    struct pci_dev *pdev;
};

static inline struct uio_pci_generic_dev *
to_uio_pci_generic_dev(struct uio_info *info)
{
    return container_of(info, struct uio_pci_generic_dev, info);
}

/* Interrupt handler. Read/modify/write the command register to disable
 * the interrupt. */
static irqreturn_t irqhandler(int irq, struct uio_info *info)
{
    struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);

    if (!pci_check_and_mask_intx(gdev->pdev))
        return IRQ_NONE;

    /* UIO core will signal the user process. */
    return IRQ_HANDLED;
}

static int __devinit probe(struct pci_dev *pdev,
               const struct pci_device_id *id)
{
    struct uio_pci_generic_dev *gdev;
    int err;

    err = pci_enable_device(pdev);
    if (err) {
        dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
            __func__, err);
        return err;
    }

    if (!pdev->irq) {
        dev_warn(&pdev->dev, "No IRQ assigned to device: "
             "no support for interrupts?\n");
        pci_disable_device(pdev);
        return -ENODEV;
    }

    if (!pci_intx_mask_supported(pdev)) {
        err = -ENODEV;
        goto err_verify;
    }

    gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
    if (!gdev) {
        err = -ENOMEM;
        goto err_alloc;
    }

    gdev->info.name = "uio_pci_generic";
    gdev->info.version = DRIVER_VERSION;
    gdev->info.irq = pdev->irq;
    gdev->info.irq_flags = IRQF_SHARED;
    gdev->info.handler = irqhandler;
    gdev->pdev = pdev;

    if (uio_register_device(&pdev->dev, &gdev->info))
        goto err_register;
    pci_set_drvdata(pdev, gdev);

    return 0;
err_register:
    kfree(gdev);
err_alloc:
err_verify:
    pci_disable_device(pdev);
    return err;
}

static void remove(struct pci_dev *pdev)
{
    struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);

    uio_unregister_device(&gdev->info);
    pci_disable_device(pdev);
    kfree(gdev);
}

static struct pci_driver driver = {
    .name = "uio_pci_generic",
    .id_table = NULL, /* only dynamic id's */
    .probe = probe,
    .remove = remove,
};

static int __init init(void)
{
    pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
    return pci_register_driver(&driver);
}

static void __exit cleanup(void)
{
    pci_unregister_driver(&driver);
}

module_init(init);
module_exit(cleanup);

MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);