/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
   *
   * Copyright (C) 2009 Red Hat, Inc.
   * Author: Michael S. Tsirkin <mst@redhat.com>
   *
   * 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 <mst@redhat.com>"
  #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
  ",
  			__func__, err);
  		return err;
  	}

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