1 /* uio_pci_generic - generic UIO driver for PCI 2.3 devices
3 * Copyright (C) 2009 Red Hat, Inc.
4 * Author: Michael S. Tsirkin <mst@redhat.com>
6 * This work is licensed under the terms of the GNU GPL, version 2.
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:
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
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.
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>
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"
33 struct uio_pci_generic_dev
{
36 spinlock_t lock
; /* guards command register accesses */
39 static inline struct uio_pci_generic_dev
*
40 to_uio_pci_generic_dev(struct uio_info
*info
)
42 return container_of(info
, struct uio_pci_generic_dev
, info
);
45 /* Interrupt handler. Read/modify/write the command register to disable
47 static irqreturn_t
irqhandler(int irq
, struct uio_info
*info
)
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
;
53 u16 origcmd
, newcmd
, status
;
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
);
60 spin_lock_irq(&gdev
->lock
);
61 pci_block_user_cfg_access(pdev
);
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;
71 /* Check interrupt status register to see whether our device
72 * triggered the interrupt. */
73 if (!(status
& PCI_STATUS_INTERRUPT
))
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
);
81 /* UIO core will signal the user process. */
85 pci_unblock_user_cfg_access(pdev
);
86 spin_unlock_irq(&gdev
->lock
);
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
93 static int __devinit
verify_pci_2_3(struct pci_dev
*pdev
)
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
) {
108 dev_err(&pdev
->dev
, "Command changed from 0x%x to 0x%x: "
109 "driver or HW bug?\n", orig
, new);
112 if (!((new ^ orig
) & PCI_COMMAND_INTX_DISABLE
)) {
113 dev_warn(&pdev
->dev
, "Device does not support "
114 "disabling interrupts: unable to bind.\n");
118 /* Now restore the original value. */
119 pci_write_config_word(pdev
, PCI_COMMAND
, orig
);
121 pci_unblock_user_cfg_access(pdev
);
125 static int __devinit
probe(struct pci_dev
*pdev
,
126 const struct pci_device_id
*id
)
128 struct uio_pci_generic_dev
*gdev
;
131 err
= pci_enable_device(pdev
);
133 dev_err(&pdev
->dev
, "%s: pci_enable_device failed: %d\n",
139 dev_warn(&pdev
->dev
, "No IRQ assigned to device: "
140 "no support for interrupts?\n");
141 pci_disable_device(pdev
);
145 err
= verify_pci_2_3(pdev
);
149 gdev
= kzalloc(sizeof(struct uio_pci_generic_dev
), GFP_KERNEL
);
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
;
161 spin_lock_init(&gdev
->lock
);
163 if (uio_register_device(&pdev
->dev
, &gdev
->info
))
165 pci_set_drvdata(pdev
, gdev
);
172 pci_disable_device(pdev
);
176 static void remove(struct pci_dev
*pdev
)
178 struct uio_pci_generic_dev
*gdev
= pci_get_drvdata(pdev
);
180 uio_unregister_device(&gdev
->info
);
181 pci_disable_device(pdev
);
185 static struct pci_driver driver
= {
186 .name
= "uio_pci_generic",
187 .id_table
= NULL
, /* only dynamic id's */
192 static int __init
init(void)
194 pr_info(DRIVER_DESC
" version: " DRIVER_VERSION
"\n");
195 return pci_register_driver(&driver
);
198 static void __exit
cleanup(void)
200 pci_unregister_driver(&driver
);
204 module_exit(cleanup
);
206 MODULE_VERSION(DRIVER_VERSION
);
207 MODULE_LICENSE("GPL v2");
208 MODULE_AUTHOR(DRIVER_AUTHOR
);
209 MODULE_DESCRIPTION(DRIVER_DESC
);
This page took 0.035356 seconds and 6 git commands to generate.