aboutsummaryrefslogtreecommitdiff
path: root/drivers/uio/uio_pci_generic.c
blob: dde5cbb2717876b59d4d1393eced78d6cddcf193 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
// SPDX-License-Identifier: GPL-2.0
/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
 *
 * Copyright (C) 2009 Red Hat, Inc.
 * Author: Michael S. Tsirkin <mst@redhat.com>
 *
 * 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);
}

static int release(struct uio_info *info, struct inode *inode)
{
	struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);

	/*
	 * This driver is insecure when used with devices doing DMA, but some
	 * people (mis)use it with such devices.
	 * Let's at least make sure DMA isn't left enabled after the userspace
	 * driver closes the fd.
	 * Note that there's a non-zero chance doing this will wedge the device
	 * at least until reset.
	 */
	pci_clear_master(gdev->pdev);
	return 0;
}

/* 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 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 && !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.release = release;
	gdev->pdev = pdev;
	if (pdev->irq) {
		gdev->info.irq = pdev->irq;
		gdev->info.irq_flags = IRQF_SHARED;
		gdev->info.handler = irqhandler;
	} else {
		dev_warn(&pdev->dev, "No IRQ assigned to device: "
			 "no support for interrupts?\n");
	}

	err = uio_register_device(&pdev->dev, &gdev->info);
	if (err)
		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 uio_pci_driver = {
	.name = "uio_pci_generic",
	.id_table = NULL, /* only dynamic id's */
	.probe = probe,
	.remove = remove,
};

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