linux设备驱动

http://blog.csdn.net/bob_fly1984/article/details/8820670

struct ov5640_data {
    struct ov5640_platform_data chip;
    bool use_smbus;

    /*  
     * Lock protects against activities from other Linux tasks,
     * but not from changes by other I2C masters.
     */
    struct mutex lock;
    struct bin_attribute bin;

    u8 *writebuf;
    unsigned write_max;
    unsigned num_addresses;

    /*  
     * Some chips tie up multiple I2C addresses; dummy devices reserve
     * them for us, and we'll use them with SMBus calls.
     */
    struct i2c_client *client[];
};

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static struct ov5640_platform_data ov5640_chip_info;

static struct i2c_board_info ov5640_i2c_board_info  __initdata ={
    .type = CONFIG_OV5640_TYPE,
    .addr = CONFIG_OV5640_DEVICE_ADDR,
};

static void __init i2c_board_init(void)
{
    int i;
    for (i = 0; i < sizeof(ov5640_list) / sizeof(struct ov5640_info); i++) {
        if (strcmp(ov5640_i2c_board_info.type, ov5640_list[i].name) == 0) {
            ov5640_chip_info.byte_len = ov5640_list[i].byte_len;
            ov5640_chip_info.page_size = ov5640_list[i].page_size;
            ov5640_chip_info.flags = ov5640_list[i].flags;
            ov5640_i2c_board_info.platform_data = &ov5640_chip_info;
            break;
        }
    }
    i2c_register_board_info(CONFIG_OV5640_I2C_BUS_NUM, &ov5640_i2c_board_info, 1);
}
这一堆是一个从设备client dev的注册

一个从设备的属性,注册通过

i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned n);

struct i2c_board_info {
    char        type[I2C_NAME_SIZE];/×相当于设备名用于区分×/
    unsigned short  flags;
    unsigned short  addr;
    void        *platform_data;    
    struct dev_archdata *archdata;
    struct device_node *of_node;   
    struct acpi_dev_node acpi_node;
    int     irq;
};

自定义一个结构体

struct ov5640_info {
    char *name;
    unsigned int byte_len;   /* size (sum of all addr) */
    unsigned short page_size;  /* for writes */
    unsigned char flags;
};

定义一个结构体数组

static const struct ov5640_info ov5640_list[] = {
    { "OV5640",   128 / 8,     1,   ov5640_FLAG_TAKE8ADDR },
    { NULL,      0,           0,   0 }  /* END OF LIST */
};

相当于busnum，几路i2c

定义一个结构体存储用户数据

struct at24_platform_data {
    u32     byte_len;       /* size (sum of all addr) */
    u16     page_size;      /* for writes */
    u8      flags;
#define AT24_FLAG_ADDR16    0x80    /* address pointer is 16 bit */
#define AT24_FLAG_READONLY  0x40    /* sysfs-entry will be read-only */
#define AT24_FLAG_IRUGO     0x20    /* sysfs-entry will be world-readable */
#define AT24_FLAG_TAKE8ADDR 0x10    /* take always 8 addresses (24c00) */

    void        (*setup)(struct memory_accessor *, void *context);
    void        *context;
};

static struct ov5640_platform_data ov5640_chip_info;

static struct i2c_board_info ov5640_i2c_board_info  __initdata ={
    .type = CONFIG_OV5640_TYPE,
    .addr = CONFIG_OV5640_DEVICE_ADDR,
};

static void __init i2c_board_init(void)
{
    int i;
    for (i = 0; i < sizeof(ov5640_list) / sizeof(struct ov5640_info); i++) {
        if (strcmp(ov5640_i2c_board_info.type, ov5640_list[i].name) == 0) {
            ov5640_chip_info.byte_len = ov5640_list[i].byte_len;
            ov5640_chip_info.page_size = ov5640_list[i].page_size;
            ov5640_chip_info.flags = ov5640_list[i].flags;
            ov5640_i2c_board_info.platform_data = &ov5640_chip_info;
            break;
        }
    }
    i2c_register_board_info(CONFIG_OV5640_I2C_BUS_NUM, &ov5640_i2c_board_info, 1);
}

将定义的platform_data注册进去

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static const struct i2c_device_id ov5640_ids[] = {
    { "OV5640", 0 },
};
MODULE_DEVICE_TABLE(i2c, ov5640_ids);

static struct i2c_driver ov5640_driver = {
    .driver = {
        .name = "OV5640",
        .owner = THIS_MODULE,
    },
    .probe = ov5640_probe,
    .remove = __devexit_p(ov5640_remove),
    .id_table = ov5640_ids,
};

i2c_driver模型

struct i2c_driver {
    unsigned int class;       

    /* Notifies the driver that a new bus has appeared. You should avoid
     * using this, it will be removed in a near future.
     */
    int (*attach_adapter)(struct i2c_adapter *) __deprecated;

    /* Standard driver model interfaces */
    int (*probe)(struct i2c_client *, const struct i2c_device_id *);
    int (*remove)(struct i2c_client *);

    /* driver model interfaces that don't relate to enumeration  */
    void (*shutdown)(struct i2c_client *);
    int (*suspend)(struct i2c_client *, pm_message_t mesg);
    int (*resume)(struct i2c_client *);

    /* Alert callback, for example for the SMBus alert protocol.
     * The format and meaning of the data value depends on the protocol.
     * For the SMBus alert protocol, there is a single bit of data passed
     * as the alert response's low bit ("event flag").
     */
    void (*alert)(struct i2c_client *, unsigned int data);

    /* a ioctl like command that can be used to perform specific functions
     * with the device.
     */
    int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);

    struct device_driver driver;
    const struct i2c_device_id *id_table;

    /* Device detection callback for automatic device creation */
    int (*detect)(struct i2c_client *, struct i2c_board_info *);
    const unsigned short *address_list;
    struct list_head clients;
};

struct i2c_client {
    unsigned short flags;       /* div., see below      */
    unsigned short addr;        /* chip address - NOTE: 7bit    */
                    /* addresses are stored in the  */
                    /* _LOWER_ 7 bits       */
    char name[I2C_NAME_SIZE];
    struct i2c_adapter *adapter;    /* the adapter we sit on    */
    struct device dev;      /* the device structure     */
    int irq;            /* irq issued by device     */
    struct list_head detected;
};

static int __init ov5640_init(void)
{
    io_limit = rounddown_pow_of_two(io_limit);
    return i2c_add_driver(&ov5640_driver);
}
module_init(ov5640_init);

static void __exit ov5640_exit(void)
{
    i2c_del_driver(&ov5640_driver);
}
module_exit(ov5640_exit);

/* eeprom device private list */