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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 * 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 int err;
76
77 err = pci_enable_device(pdev);
78 if (err) {
79 dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
80 __func__, err);
81 return err;
82 }
83
84 if (pdev->irq && !pci_intx_mask_supported(pdev)) {
85 err = -ENODEV;
86 goto err_verify;
87 }
88
89 gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
90 if (!gdev) {
91 err = -ENOMEM;
92 goto err_alloc;
93 }
94
95 gdev->info.name = "uio_pci_generic";
96 gdev->info.version = DRIVER_VERSION;
97 gdev->info.release = release;
98 gdev->pdev = pdev;
99 if (pdev->irq) {
100 gdev->info.irq = pdev->irq;
101 gdev->info.irq_flags = IRQF_SHARED;
102 gdev->info.handler = irqhandler;
103 } else {
104 dev_warn(&pdev->dev, "No IRQ assigned to device: "
105 "no support for interrupts?\n");
106 }
107
108 err = uio_register_device(&pdev->dev, &gdev->info);
109 if (err)
110 goto err_register;
111 pci_set_drvdata(pdev, gdev);
112
113 return 0;
114err_register:
115 kfree(gdev);
116err_alloc:
117err_verify:
118 pci_disable_device(pdev);
119 return err;
120}
121
122static void remove(struct pci_dev *pdev)
123{
124 struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
125
126 uio_unregister_device(&gdev->info);
127 pci_disable_device(pdev);
128 kfree(gdev);
129}
130
131static struct pci_driver uio_pci_driver = {
132 .name = "uio_pci_generic",
133 .id_table = NULL, /* only dynamic id's */
134 .probe = probe,
135 .remove = remove,
136};
137
138module_pci_driver(uio_pci_driver);
139MODULE_VERSION(DRIVER_VERSION);
140MODULE_LICENSE("GPL v2");
141MODULE_AUTHOR(DRIVER_AUTHOR);
142MODULE_DESCRIPTION(DRIVER_DESC);
1/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
2 *
3 * Copyright (C) 2009 Red Hat, Inc.
4 * Author: Michael S. Tsirkin <mst@redhat.com>
5 *
6 * This work is licensed under the terms of the GNU GPL, version 2.
7 *
8 * Since the driver does not declare any device ids, you must allocate
9 * id and bind the device to the driver yourself. For example:
10 *
11 * # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
12 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
13 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
14 * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
15 * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
16 *
17 * Driver won't bind to devices which do not support the Interrupt Disable Bit
18 * in the command register. All devices compliant to PCI 2.3 (circa 2002) and
19 * all compliant PCI Express devices should support this bit.
20 */
21
22#include <linux/device.h>
23#include <linux/module.h>
24#include <linux/pci.h>
25#include <linux/slab.h>
26#include <linux/uio_driver.h>
27#include <linux/spinlock.h>
28
29#define DRIVER_VERSION "0.01.0"
30#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@redhat.com>"
31#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"
32
33struct uio_pci_generic_dev {
34 struct uio_info info;
35 struct pci_dev *pdev;
36 spinlock_t lock; /* guards command register accesses */
37};
38
39static inline struct uio_pci_generic_dev *
40to_uio_pci_generic_dev(struct uio_info *info)
41{
42 return container_of(info, struct uio_pci_generic_dev, info);
43}
44
45/* Interrupt handler. Read/modify/write the command register to disable
46 * the interrupt. */
47static irqreturn_t irqhandler(int irq, struct uio_info *info)
48{
49 struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
50 struct pci_dev *pdev = gdev->pdev;
51 irqreturn_t ret = IRQ_NONE;
52 u32 cmd_status_dword;
53 u16 origcmd, newcmd, status;
54
55 /* We do a single dword read to retrieve both command and status.
56 * Document assumptions that make this possible. */
57 BUILD_BUG_ON(PCI_COMMAND % 4);
58 BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);
59
60 spin_lock_irq(&gdev->lock);
61 pci_block_user_cfg_access(pdev);
62
63 /* Read both command and status registers in a single 32-bit operation.
64 * Note: we could cache the value for command and move the status read
65 * out of the lock if there was a way to get notified of user changes
66 * to command register through sysfs. Should be good for shared irqs. */
67 pci_read_config_dword(pdev, PCI_COMMAND, &cmd_status_dword);
68 origcmd = cmd_status_dword;
69 status = cmd_status_dword >> 16;
70
71 /* Check interrupt status register to see whether our device
72 * triggered the interrupt. */
73 if (!(status & PCI_STATUS_INTERRUPT))
74 goto done;
75
76 /* We triggered the interrupt, disable it. */
77 newcmd = origcmd | PCI_COMMAND_INTX_DISABLE;
78 if (newcmd != origcmd)
79 pci_write_config_word(pdev, PCI_COMMAND, newcmd);
80
81 /* UIO core will signal the user process. */
82 ret = IRQ_HANDLED;
83done:
84
85 pci_unblock_user_cfg_access(pdev);
86 spin_unlock_irq(&gdev->lock);
87 return ret;
88}
89
90/* Verify that the device supports Interrupt Disable bit in command register,
91 * per PCI 2.3, by flipping this bit and reading it back: this bit was readonly
92 * in PCI 2.2. */
93static int __devinit verify_pci_2_3(struct pci_dev *pdev)
94{
95 u16 orig, new;
96 int err = 0;
97
98 pci_block_user_cfg_access(pdev);
99 pci_read_config_word(pdev, PCI_COMMAND, &orig);
100 pci_write_config_word(pdev, PCI_COMMAND,
101 orig ^ PCI_COMMAND_INTX_DISABLE);
102 pci_read_config_word(pdev, PCI_COMMAND, &new);
103 /* There's no way to protect against
104 * hardware bugs or detect them reliably, but as long as we know
105 * what the value should be, let's go ahead and check it. */
106 if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) {
107 err = -EBUSY;
108 dev_err(&pdev->dev, "Command changed from 0x%x to 0x%x: "
109 "driver or HW bug?\n", orig, new);
110 goto err;
111 }
112 if (!((new ^ orig) & PCI_COMMAND_INTX_DISABLE)) {
113 dev_warn(&pdev->dev, "Device does not support "
114 "disabling interrupts: unable to bind.\n");
115 err = -ENODEV;
116 goto err;
117 }
118 /* Now restore the original value. */
119 pci_write_config_word(pdev, PCI_COMMAND, orig);
120err:
121 pci_unblock_user_cfg_access(pdev);
122 return err;
123}
124
125static int __devinit probe(struct pci_dev *pdev,
126 const struct pci_device_id *id)
127{
128 struct uio_pci_generic_dev *gdev;
129 int err;
130
131 err = pci_enable_device(pdev);
132 if (err) {
133 dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
134 __func__, err);
135 return err;
136 }
137
138 if (!pdev->irq) {
139 dev_warn(&pdev->dev, "No IRQ assigned to device: "
140 "no support for interrupts?\n");
141 pci_disable_device(pdev);
142 return -ENODEV;
143 }
144
145 err = verify_pci_2_3(pdev);
146 if (err)
147 goto err_verify;
148
149 gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
150 if (!gdev) {
151 err = -ENOMEM;
152 goto err_alloc;
153 }
154
155 gdev->info.name = "uio_pci_generic";
156 gdev->info.version = DRIVER_VERSION;
157 gdev->info.irq = pdev->irq;
158 gdev->info.irq_flags = IRQF_SHARED;
159 gdev->info.handler = irqhandler;
160 gdev->pdev = pdev;
161 spin_lock_init(&gdev->lock);
162
163 if (uio_register_device(&pdev->dev, &gdev->info))
164 goto err_register;
165 pci_set_drvdata(pdev, gdev);
166
167 return 0;
168err_register:
169 kfree(gdev);
170err_alloc:
171err_verify:
172 pci_disable_device(pdev);
173 return err;
174}
175
176static void remove(struct pci_dev *pdev)
177{
178 struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
179
180 uio_unregister_device(&gdev->info);
181 pci_disable_device(pdev);
182 kfree(gdev);
183}
184
185static struct pci_driver driver = {
186 .name = "uio_pci_generic",
187 .id_table = NULL, /* only dynamic id's */
188 .probe = probe,
189 .remove = remove,
190};
191
192static int __init init(void)
193{
194 pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
195 return pci_register_driver(&driver);
196}
197
198static void __exit cleanup(void)
199{
200 pci_unregister_driver(&driver);
201}
202
203module_init(init);
204module_exit(cleanup);
205
206MODULE_VERSION(DRIVER_VERSION);
207MODULE_LICENSE("GPL v2");
208MODULE_AUTHOR(DRIVER_AUTHOR);
209MODULE_DESCRIPTION(DRIVER_DESC);