参考资料:
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Linux驱动程序:
drivers/i2c/i2c-dev.c
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I2C-Tools-4.2:
https://mirrors.edge.kernel.org/pub/software/utils/i2c-tools/
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AT24cxx.pdf
1. 回顾字符设备驱动程序
怎么编写字符设备驱动程序?
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确定主设备号
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创建file_operations结构体
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在里面填充drv_open/drv_read/drv_ioctl等函数
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注册file_operations结构体
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register_chrdev(major, &fops, name)
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谁调用register_chrdev?在入口函数调用
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有入口自然就有出口
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在出口函数unregister_chrdev
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辅助函数(帮助系统自动创建设备节点)
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class_create
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device_create
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2. i2c-dev.c注册过程分析
2.1 register_chrdev的内部实现
2.2 i2c-dev驱动的注册过程
3. file_operations函数分析
i2c-dev.c的核心:
static const struct file_operations i2cdev_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = i2cdev_read,
.write = i2cdev_write,
.unlocked_ioctl = i2cdev_ioctl,
.compat_ioctl = compat_i2cdev_ioctl,
.open = i2cdev_open,
.release = i2cdev_release,
};
主要的系统调用:open, ioctl:
要理解这些接口,记住一句话:APP通过I2C Controller与I2C Device传输数据。
3.1 i2cdev_open
3.2 i2cdev_ioctl: I2C_SLAVE/I2C_SLAVE_FORCE
3.3 i2cdev_ioctl: I2C_RDWR
3.4 i2cdev_ioctl: I2C_SMBUS
3.5 总结
标签:I2C,dev,ioctl,i2cdev,驱动,i2c,open From: https://www.cnblogs.com/liusiluandzhangkun/p/17591696.html