#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#include <asm/uaccess.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>//主设备号
static int major;
//类描述为创建设备使用
static struct class *cls;
//i2c client 发送接收数据使用
static struct i2c_client *at24cxx_client;//互斥锁
static struct mutex at24cxx_mutex;//i2c table 和 board 中进行比较 相同调用 probe
static struct i2c_device_id at24cxx_id_table[] = {{"at24c08", 0},{}
};//mmap 使用内存
static unsigned char *at24cxx_buf;
//物理地址 使用和 lcd fb 一样的分配内存的方法 dma_alloc_writecombine
static dma_addr_t at24cxx_phys;#define AT24cxx_BUF_SIZE 64static int at24cxx_mmap(struct file *file, struct vm_area_struct *vma)
{u64 len = vma->vm_end - vma->vm_start;len = min(len, AT24cxx_BUF_SIZE);//no cachevma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);return vm_iomap_memory(vma, at24cxx_phys, len);
}static int at24cxx_open(struct inode *note, struct file *f)
{//打开时 填充 mmap 的bufint i;memset(at24cxx_buf, 0, AT24cxx_BUF_SIZE);for(i=0; i<AT24cxx_BUF_SIZE; i++){at24cxx_buf[i] = i2c_smbus_read_byte_data(at24cxx_client, i);}return 0;
}static int at24cxx_release(struct inode *note, struct file *f)
{//写 mmap 中的数据回 at24c08int i;for(i=0; i<AT24cxx_BUF_SIZE; i++){i2c_smbus_write_byte_data(at24cxx_client, i, at24cxx_buf[i]);mdelay(100);}return 0;
}static struct file_operations at24cxx_ops = {.owner   = THIS_MODULE,.open    = at24cxx_open,.release = at24cxx_release,.mmap    = at24cxx_mmap,
};//当idtab中比较相同以后调用这个
static int at24cxx_probe(struct i2c_client *client,const struct i2c_device_id *dev)
{//初始化锁mutex_init(&at24cxx_mutex);//设给全局变量at24cxx_client = client;//创建字库设备cls = class_create(THIS_MODULE, "at24cxx");major = register_chrdev(0, "at24cxx", &at24cxx_ops);device_create(cls, NULL, MKDEV(major, 0), NULL, "at24cxx");//vmalloc 分配的物理地址连续at24cxx_buf = dma_alloc_writecombine(NULL, AT24cxx_BUF_SIZE, &at24cxx_phys, GFP_KERNEL);return 0;
}static int at24cxx_remove(struct i2c_client *client)
{device_destroy(cls, MKDEV(major, 0));class_destroy(cls);unregister_chrdev(major, "at24cxx");dma_free_writecombine(NULL, AT24cxx_BUF_SIZE, at24cxx_buf, at24cxx_phys);return 0;
}static struct i2c_driver at24cxx_drv = {.driver = {.name  = "at24cxx",.owner = THIS_MODULE,},.probe  = at24cxx_probe,.remove = at24cxx_remove,.id_table = at24cxx_id_table,
};static int at24cxx_init(void)
{i2c_add_driver(&at24cxx_drv);return 0;
}static void at24cxx_exit(void)
{i2c_del_driver(&at24cxx_drv);
}module_init(at24cxx_init);
module_exit(at24cxx_exit);
MODULE_LICENSE("GPL");