编写一段基于linux内核的pcie mailbox测试用例驱动

这是一个简单的基于Linux内核的PCIe Mailbox测试用例驱动，用于测试PCIe设备与主机之间的通讯。

1.包含头文件

#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

2.定义PCIe设备的Vendor ID和Device ID

#define VENDOR_ID 0x10EC
#define DEVICE_ID 0x8168

3.定义PCIe设备的寄存器偏移量

#define MAILBOX_CTRL_REG 0x00
#define MAILBOX_STATUS_REG 0x04
#define MAILBOX_DATA_REG 0x08

4.定义PCIe设备的寄存器结构

struct mailbox_regs {
u32 ctrl_reg;
u32 status_reg;
u32 data_reg;
};

5.定义设备驱动程序的数据结构

struct mailbox_dev {
struct pci_dev *pdev;
void __iomem *regs;
};

6.定义设备驱动程序的常量

#define DRIVER_NAME "mailbox_driver"

7.定义设备驱动程序的probe函数

static int mailbox_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct mailbox_dev *mdev;
int ret;

printk(KERN_INFO "Mailbox device detected\n");

mdev = kzalloc(sizeof(struct mailbox_dev), GFP_KERNEL);
if (!mdev) {
printk(KERN_ERR "Failed to allocate memory for mailbox device\n");
return -ENOMEM;
}

ret = pci_enable_device(pdev);
if (ret) {
printk(KERN_ERR "Failed to enable PCI device\n");
goto err_free;
}

ret = pci_request_regions(pdev, DRIVER_NAME);
if (ret) {
printk(KERN_ERR "Failed to request PCI regions\n");
goto err_disable;
}

mdev->pdev = pdev;
mdev->regs = pci_iomap(pdev, 0, 0);
if (!mdev->regs) {
printk(KERN_ERR "Failed to map PCI IO space\n");
goto err_release;
}

printk(KERN_INFO "Mailbox device initialized\n");

return 0;

err_release:
pci_release_regions(pdev);
err_disable:
pci_disable_device(pdev);
err_free:
kfree(mdev);

return ret;
}

8.定义设备驱动程序的remove函数

static void mailbox_remove(struct pci_dev *pdev)
{
struct mailbox_dev *mdev = pci_get_drvdata(pdev);

printk(KERN_INFO "Removing Mailbox device\n");

pci_iounmap(pdev, mdev->regs);
pci_release_regions(pdev);
pci_disable_device(pdev);
kfree(mdev);
}

9.定义设备驱动程序的PCIe设备ID和Vendor ID

static const struct pci_device_id mailbox_id_table[] = {
{ PCI_DEVICE(VENDOR_ID, DEVICE_ID), },
{ 0, }
};

MODULE_DEVICE_TABLE(pci, mailbox_id_table);

10.定义设备驱动程序的PCIe设备驱动结构

static struct pci_driver mailbox_driver = {
.name = DRIVER_NAME,
.id_table = mailbox_id_table,
.probe = mailbox_probe,
.remove = mailbox_remove,
};

11.定义驱动程序的入口函数

static int __init mailbox_init(void)
{
int ret;

ret = pci_register_driver(&mailbox_driver);
if (ret) {
printk(KERN_ERR "Failed to register Mailbox driver\n");
return ret;
}

printk(KERN_INFO "Mailbox driver registered\n");

return 0;
}

12.定义驱动程序的出口函数

static void __exit mailbox_exit(void)
{
pci_unregister_driver(&mailbox_driver);

printk(KERN_INFO "Mailbox driver unregistered\n");
}

13.将驱动程序的入口和出口函数注册到内核

module_init(mailbox_init);
module_exit(mailbox_exit);

14.在模块描述符中添加模块许可证信息和作者信息

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");

15.编译和安装模块

make
sudo insmod mailbox_driver.ko

16.测试PCIe Mailbox功能

通过读写PCIe设备的寄存器来测试PCIe Mailbox功能：

#define MAILBOX_ENABLE_BIT (1 << 0)

void mailbox_test(struct mailbox_dev *mdev)
{
struct mailbox_regs *regs = (struct mailbox_regs *)mdev->regs;

// Enable the mailbox
writel(MAILBOX_ENABLE_BIT, &regs->ctrl_reg);

// Write data to the mailbox
writel(0x12345678, &regs->data_reg);

// Wait for the mailbox to be ready
while (!(readl(&regs->status_reg) & MAILBOX_ENABLE_BIT));

// Read data from the mailbox
u32 data = readl(&regs->data_reg);
printk(KERN_INFO "Mailbox data: %08x\n", data);
}

17.卸载模块

sudo rmmod mailbox_driver