驱动模块使用I2C总线范例

原文http://blog.csdn.net/azloong/article/details/6178657

源码是在linux２.6下写的，为了移值到更高的linux版本，进行了一定的修改。

#include <linux/kernel.h>#include <linux/module.h>#include <linux/init.h>#include <linux/errno.h>#include <linux/init.h>#include <linux/list.h>#include <linux/i2c.h>#include <linux/hardirq.h>#include <linux/slab.h>   #define I2C_API_FAKE_ADDR   0x7f#define I2C_MINORS          256//#define i2c_version_old     1   int  i2c_api_attach(struct i2c_adapter *adapter);int  i2c_api_detach(struct i2c_adapter *adapter); struct i2c_api {    struct list_head list;    struct i2c_client *client;}; static LIST_HEAD(i2c_api_list);static DEFINE_SPINLOCK(i2c_api_list_lock); static const unsigned short normal_addr[] = { I2C_API_FAKE_ADDR, I2C_CLIENT_END };static const unsigned short ignore[]      = { I2C_CLIENT_END };#ifdef i2c_version_oldstatic struct i2c_client_address_data addr_data =  {    .normal_i2c = normal_addr,    .probe      = ignore,    .ignore     = ignore,    .forces     = NULL,};#endifstatic const struct i2c_device_id id[] = {    {"I2C-API", 0},    {}  };       MODULE_DEVICE_TABLE(i2c, id); static struct i2c_driver i2c_api_driver = {    .id_table       = id,    .attach_adapter = i2c_api_attach, //#if LINUX_VERSION_CODE < KERNEL_VERSION(3,10,0)    #if 0    .detach_adapter    = i2c_api_detach,#endif        .command        = NULL,    .driver         = {.name  = "I2C-API",.owner = THIS_MODULE,    },#ifdef i2c_version_old        .address_data   = &addr_data,#endif }; static struct i2c_api *get_i2c_api(int bus_id){    struct i2c_api *i2c_api;     spin_lock(&i2c_api_list_lock);    list_for_each_entry(i2c_api, &i2c_api_list, list) {        if (i2c_api->client->adapter->nr == bus_id)            goto found;    }    i2c_api = NULL;    found:    spin_unlock(&i2c_api_list_lock);    return i2c_api;} static struct i2c_api *add_i2c_api(struct i2c_client *client){    struct i2c_api *i2c_api;     if (client->adapter->nr >= I2C_MINORS) {        printk(KERN_ERR "i2c_api: Out of device minors (%d)/n",            client->adapter->nr);        return NULL;    }     i2c_api = kzalloc(sizeof(*i2c_api), GFP_KERNEL);    if (!i2c_api)        return NULL;    i2c_api->client = client;     spin_lock(&i2c_api_list_lock);    list_add_tail(&i2c_api->list, &i2c_api_list);    spin_unlock(&i2c_api_list_lock);    return i2c_api;} static void del_i2c_api(struct i2c_api *i2c_api){    spin_lock(&i2c_api_list_lock);    list_del(&i2c_api->list);    spin_unlock(&i2c_api_list_lock);    kfree(i2c_api);} static int i2c_api_do_xfer(int bus_id, char chip_addr, char sub_addr, int mode,      char *buf, unsigned int size){/** you could define more transfer mode here, implement it following. */#define I2C_API_XFER_MODE_SEND            0x0 /* standard send */#define I2C_API_XFER_MODE_RECV            0x1 /* standard receive */#define I2C_API_XFER_MODE_SEND_NO_SUBADDR 0x2 /* send without sub-address */#define I2C_API_XFER_MODE_RECV_NO_SUBADDR 0x3 /* receive without sub-address */     int ret = 0;    char *tmp;    struct i2c_api *i2c_api = get_i2c_api(bus_id);     if (!i2c_api)        return -ENODEV;        i2c_api->client->addr = chip_addr;    switch (mode) {    case I2C_API_XFER_MODE_SEND:        tmp = kmalloc(size + 1,GFP_KERNEL);        if (tmp == NULL)            return -ENOMEM;        tmp[0] = sub_addr;        memcpy(&tmp[1], buf, size);        ret = i2c_master_send(i2c_api->client, tmp, size + 1);        ret = (ret == size + 1) ? size : ret;        break;            case I2C_API_XFER_MODE_RECV:        ret = i2c_master_send(i2c_api->client, &sub_addr, 1);        if (ret < 0)            return ret;        ret = i2c_master_recv(i2c_api->client, buf, size);        break;        case I2C_API_XFER_MODE_SEND_NO_SUBADDR:        ret = i2c_master_send(i2c_api->client, buf, size);        break;            case I2C_API_XFER_MODE_RECV_NO_SUBADDR:        ret = i2c_master_recv(i2c_api->client, buf, size);        break;                default:        return -EINVAL;    }    return ret;} int i2c_api_do_send(int bus_id, char chip_addr, char sub_addr, char *buf, unsigned int size){    return i2c_api_do_xfer(bus_id, chip_addr, sub_addr, I2C_API_XFER_MODE_SEND, buf, size);} int i2c_api_do_recv(int bus_id, char chip_addr, char sub_addr, char *buf, unsigned int size){    return i2c_api_do_xfer(bus_id, chip_addr, sub_addr, I2C_API_XFER_MODE_RECV, buf, size);} int i2c_api_attach(struct i2c_adapter *adap){    struct i2c_board_info info;    struct i2c_client *client;        memset(&info, 0, sizeof(struct i2c_board_info));        strlcpy(info.type, "i2c_api", I2C_NAME_SIZE);    info.addr = I2C_API_FAKE_ADDR;    client = i2c_new_device(adap, &info);    if (client)        add_i2c_api(client);    printk(KERN_INFO "i2c_api_attach adap[%d]/n", adap->nr);    return 0;} int i2c_api_detach(struct i2c_adapter *adap){        struct i2c_api *i2c_api;     i2c_api = get_i2c_api(adap->nr);    if (i2c_api)        del_i2c_api(i2c_api);    return 0;} static int __init i2c_api_init(void){        int ret = i2c_add_driver(&i2c_api_driver);      if (ret) {        printk(KERN_ERR "[%s] Driver registration failed, module not inserted./n", __func__);        return ret;    }     return 0 ;    } static void __exit i2c_api_exit(void){        i2c_del_driver(&i2c_api_driver);} MODULE_AUTHOR("Loon, <[e-mail]>");MODULE_DESCRIPTION("I2C i2c_api Driver");MODULE_LICENSE("GPL"); module_init(i2c_api_init);module_exit(i2c_api_exit); EXPORT_SYMBOL_GPL(i2c_api_do_send);EXPORT_SYMBOL_GPL(i2c_api_do_recv);