上一篇文章写了字符设备驱动的基本结构及访问方式,在实际应用时首先需要绑定自己的硬件设备。本篇主要描述字符设备驱动与PCI接口类型的设备访问方式(内核为2.6.24及以上的方法,测试内核为2.6.32)。
首先介绍下PCI驱动结构:
//PCI设备id描述结构:这里有两个参数 第一个是VendorID,第二个是DeviceID(在linux Terminal中输入 lspci -vmm可以看到设备信息)
static struct pci_device_id pci_ids[] = {
{ PCI_DEVICE(Vendor,Device) },
{ 0 }
};
//PCI设备描述结构:指定PCI设备函数
static struct pci_driver driver_ops = {
.name = DevName,//驱动名称
.id_table = pci_ids,//PCI设备id描述结构
.probe = pci_probe,//PCI入口函数
.remove = pci_remove,//PCI退出函数
};
//PCI驱动注册函数
//注意项:如果没有探测到 PCI设备id描述结构(指定的VendorID或DeviceID在Terminal中查找不到)或者指定的设备已经绑定了驱动,那么PCI入口函数以及PCI退出函数不会执行(PCI设备描述结构内指定的别的函数也是如此)
pci_register_driver(&driver_ops);
下面展示PCI驱动调用字符设备驱动的实例:
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/device.h>
#define DevName "test"
#define ClassName "class_test"
#define VendorID 0xFA01
#define DeviceID 0x1234
struct class *mem_class;
struct Pci_Test
{
struct cdev _cdev;
dev_t dev;
char msi_enabled;
}*pci_test;
static int Test_open(struct inode *inode,struct file *filp)
{
return 0;
}
static int Test_release(struct inode *inode,struct file *filp)
{
return 0;
}
static struct file_operations test_fops = {
.owner = THIS_MODULE,
//.ioctl = Test_ioctl,
.open = Test_open,
.release = Test_release,
};
//字符驱动
static init_chrdev(struct Pci_Test *test_ptr)
{
int result = alloc_chrdev_region(&test_ptr->dev, 0, 2, DevName);
if (result < 0)
{
printk("Err:failed in alloc_chrdev_region!\n");
return result;
}
mem_class = class_create(THIS_MODULE,ClassName);// /dev/ create devfile
if (IS_ERR(mem_class))
{
printk("Err:failed in creating class!\n");
}
device_create(mem_class,NULL,test_ptr->dev,NULL,DevName);
cdev_init(&test_ptr->_cdev,&test_fops);
test_ptr->_cdev.owner = THIS_MODULE;
test_ptr->_cdev.ops = &test_fops;//Create Dev and file_operations Connected
result = cdev_add(&test_ptr->_cdev,test_ptr->dev,1);
return result;
}
//PCI驱动入口函数
static int __init pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
int rc = 0;
pci_test = dev;
pci_set_drvdata(dev, pci_test);
//在这里创建字符设备驱动
rc = init_chrdev(pci_test);
if (rc) {
dev_err(&dev->dev, "init_chrdev() failed\n");
return -1;
}
rc = pci_enable_device(dev);
if (rc) {
dev_err(&dev->dev, "pci_enable_device() failed\n");
return -1;
}
rc = pci_request_regions(dev, DevName);
if (rc) {
dev_err(&dev->dev, "pci_request_regions() failed\n");
return -1;
}
pci_set_master(dev);
rc = pci_enable_msi(dev);
if (rc) {
dev_info(&dev->dev, "pci_enable_msi() failed\n");
pci_test->msi_enabled = 0;
} else {
dev_info(&dev->dev, "pci_enable_msi() successful\n");
pci_test->msi_enabled = 1;
}
return rc;
}
static void __exit pci_remove(struct pci_dev *dev)
{
if (0 != mem_class)
{
device_destroy(mem_class,pci_test->dev);
class_destroy(mem_class);
mem_class = 0;
}
pci_test = pci_get_drvdata(dev);
cdev_del(&pci_test->_cdev);
unregister_chrdev_region(pci_test->dev, 1);
pci_disable_device(dev);
if(pci_test) {
if(pci_test->msi_enabled) {
pci_disable_msi(dev);
pci_test->msi_enabled = 0;
}
}
pci_release_regions(dev);
}
static struct pci_device_id pci_ids[] = {
{ PCI_DEVICE( VendorID, DeviceID) },
{ 0 }
};
static struct pci_driver driver_ops = {
.name = DevName,
.id_table = pci_ids,
.probe = pci_probe,
.remove = pci_remove,
};
//驱动模块入口函数
static int Test_init_module(void)
{
int rc = 0;
pci_test = kzalloc(sizeof(struct Pci_Test), GFP_KERNEL);
//配对设备以及注册PCI驱动,如果找到对应设备调用PCI入口函数
rc = pci_register_driver(&driver_ops);
if (rc) {
printk(KERN_ALERT ": PCI driver registration failed\n");
}
return rc;
}
static void Test_exit_module(void)
{
pci_unregister_driver(&driver_ops);
kfree(pci_test);
}
module_init(Test_init_module);
module_exit(Test_exit_module);
MODULE_AUTHOR(DevName);
MODULE_LICENSE("GPL");
当PCI驱动与硬件设备绑定成功时,便可以通过字符设备驱动访问设备了。
上一篇linux使用open打开字符设备驱动:http://blog.csdn.net/a29562268/article/details/78443087!