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	��* 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. */
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