设备与驱动匹配1.match过程i2c_add_driver-->i2c_register_driver-->i2c_bus_type-->.match->i2c_device_match-->of_driver_match_device/i2c_match_id(比较i2c_driver->id_table->name和client->name,如果相同,则匹配上,匹配上之后,运行driver_register调用driver_probe_device进行设备与驱动绑定。),////////////static int __init at24_init(void){    io_limit = rounddown_pow_of_two(io_limit);//执行完i2c_add_numbered_adapter函数后,内核的i2c总线上已有adapter device和client device// .id_table = at24_ids中的名字和i2c_client中的名字 进行匹配    return i2c_add_driver(&at24_driver);}module_init(at24_init);////////////////////////////////////////////////////////////////////////////////static struct i2c_driver at24_driver = {    .driver = {        .name = "at24",//这个名字用于创建文件,不用于匹配        .owner = THIS_MODULE,    }, ///当i2c_client和i2c_driver(at24_driver)匹配时调用    .probe = at24_probe,    .remove = __devexit_p(at24_remove),//ID表是用来和i2c_client匹配用的,//  static struct i2c_board_info i2c_devs0[]用来建立i2c_client(相当于device)////int i2c_attach_client(struct i2c_client *client)//i2c_new_device函数    .id_table = at24_ids,};////////////////////////////////////////////////////////////////////////////////////////////////struct i2c_client *i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)//   ------> strlcpy(client->name, info->type, sizeof(client->name));// i2c_board_info中的名字给了client//static struct i2c_board_info i2c_devs0[]////"24c08"这个名字就是用来创建i2c_client来和里static struct i2c_driver at24_driver进行匹配的。static const struct i2c_device_id at24_ids[] = {    /* needs 8 addresses as A0-A2 are ignored */    /* old variants can't be handled with this generic entry! */    { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },    { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },    /* spd is a 24c02 in memory DIMMs */    { "spd", AT24_DEVICE_MAGIC(2048 / 8,        AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },    { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },    /* 24rf08 quirk is handled at i2c-core */    { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },    { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },    { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },    { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },    { "at24", 0 },    { /* END OF LIST */ }};/////////////////////////////////////////////////////////////////////////////////////////////*-------------------------------------------------------------------------*/static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id){    struct at24_platform_data chip;    bool writable;    bool use_smbus = false;    struct at24_data *at24;    int err;    unsigned i, num_addresses;    kernel_ulong_t magic;    if (client->dev.platform_data) {        chip = *(struct at24_platform_data *)client->dev.platform_data;    }        magic = id->driver_data;        chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));        magic >>= AT24_SIZE_BYTELEN;        chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);        /*         * This is slow, but we can't know all eeproms, so we better         * play safe. Specifying custom eeprom-types via platform_data         * is recommended anyhow.         */        chip.page_size = 1;    }    if (!is_power_of_2(chip.byte_len))        dev_warn(&client->dev,            "byte_len looks suspicious (no power of 2)!\n");    if (!is_power_of_2(chip.page_size))        dev_warn(&client->dev,            "page_size looks suspicious (no power of 2)!\n");    /* Use I2C operations unless we're stuck with SMBus extensions. */    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {        if (chip.flags & AT24_FLAG_ADDR16) {            err = -EPFNOSUPPORT;            goto err_out;        }        if (!i2c_check_functionality(client->adapter,                I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {            err = -EPFNOSUPPORT;            goto err_out;        }        use_smbus = true;    }    if (chip.flags & AT24_FLAG_TAKE8ADDR)        num_addresses = 8;    else        num_addresses =    DIV_ROUND_UP(chip.byte_len,            (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);    at24 = kzalloc(sizeof(struct at24_data) +        num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);    if (!at24) {        err = -ENOMEM;        goto err_out;    }    mutex_init(&at24->lock);    at24->use_smbus = use_smbus;    at24->chip = chip;    at24->num_addresses = num_addresses;    /*     * Export the EEPROM bytes through sysfs, since that's convenient.     * By default, only root should see the data (maybe passwords etc)     */    at24->bin.attr.name = "eeprom";    at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;//除了这种操作i2c设备的方法外,////static int __init i2c_dev_init(void)//res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops); 也是一种操作i2c设备的方法    at24->bin.read = at24_bin_read;    at24->bin.size = chip.byte_len;    writable = !(chip.flags & AT24_FLAG_READONLY);    if (writable) {        if (!use_smbus || i2c_check_functionality(client->adapter,                I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {            unsigned write_max = chip.page_size;            at24->bin.write = at24_bin_write;            at24->bin.attr.mode |= S_IWUSR;            if (write_max > io_limit)                write_max = io_limit;            if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)                write_max = I2C_SMBUS_BLOCK_MAX;            at24->write_max = write_max;            /* buffer (data + address at the beginning) */            at24->writebuf = kmalloc(write_max + 2, GFP_KERNEL);        }    }    at24->client[0] = client;    /* use dummy devices for multiple-address chips */    for (i = 1; i        at24->client[i] = i2c_new_dummy(client->adapter,                    client->addr + i);        if (!at24->client[i]) {            dev_err(&client->dev, "address 0x%02x unavailable\n",                    client->addr + i);            err = -EADDRINUSE;            goto err_clients;        }    }    err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);    if (err)        goto err_clients;    i2c_set_clientdata(client, at24);    dev_info(&client->dev, "%zu byte %s EEPROM %s\n",        at24->bin.size, client->name,        writable ? "(writable)" : "(read-only)");    dev_dbg(&client->dev,        "page_size %d, num_addresses %d, write_max %d%s\n",        chip.page_size, num_addresses,        at24->write_max,        use_smbus ? ", use_smbus" : "");    return 0;err_clients:    for (i = 1; i        if (at24->client[i])            i2c_unregister_device(at24->client[i]);    kfree(at24->writebuf);err_struct:    kfree(at24);err_out:    dev_dbg(&client->dev, "probe error %d\n", err);    return err;}////////////////////////////////////////////////////////////////////////////////////////////static ssize_t at24_bin_read(struct kobject *kobj, struct bin_attribute *attr,        char *buf, loff_t off, size_t count){    struct at24_data *at24;    ssize_t retval = 0;    at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));    /*     * Read data from chip, protecting against concurrent updates     * from this host, but not from other I2C masters.     */    mutex_lock(&at24->lock);    while (count) {        ssize_t    status;        status = at24_eeprom_read(at24, buf, off, count);        if (status            if (retval == 0)                retval = status;            break;        }        buf += status;        off += status;        count -= status;        retval += status;    }    mutex_unlock(&at24->lock);    return retval;}////////////////////////////////////////////////////////////////////////////////////////////static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,        unsigned offset, size_t count){    struct i2c_msg msg[2];    u8 msgbuf[2];    struct i2c_client *client;    int status, i;    memset(msg, 0, sizeof(msg));    /*     * REVISIT some multi-address chips don't rollover page reads to     * the next slave address, so we may need to truncate the count.     * Those chips might need another quirk flag.     *     * If the real hardware used four adjacent 24c02 chips and that     * were misconfigured as one 24c08, that would be a similar effect:     * one "eeprom" file not four, but larger reads would fail when     * they crossed certain pages.     */    /*     * Slave address and byte offset derive from the offset. Always     * set the byte address; on a multi-master board, another master     * may have changed the chip's "current" address pointer.     */    client = at24_translate_offset(at24, &offset);    if (count > io_limit)        count = io_limit;    /* Smaller eeproms can work given some SMBus extension calls */    if (at24->use_smbus) {        if (count > I2C_SMBUS_BLOCK_MAX)            count = I2C_SMBUS_BLOCK_MAX;        status = i2c_smbus_read_i2c_block_data(client, offset,                count, buf);        dev_dbg(&client->dev, "smbus read %zu@%d --> %d\n",                count, offset, status);        return (status    }    /*     * When we have a better choice than SMBus calls, use a combined     * I2C message. Write address; then read up to io_limit data bytes.     * Note that read page rollover helps us here (unlike writes).     * msgbuf is u8 and will cast to our needs.     */    i = 0;    if (at24->chip.flags & AT24_FLAG_ADDR16)        msgbuf[i++] = offset >> 8;    msgbuf[i++] = offset;    msg[0].addr = client->addr;    msg[0].buf = msgbuf;    msg[0].len = i;    msg[1].addr = client->addr;    msg[1].flags = I2C_M_RD;    msg[1].buf = buf;    msg[1].len = count; 中有i2c_transfer    status = i2c_transfer(client->adapter, msg, 2);    dev_dbg(&client->dev, "i2c read %zu@%d --> %d\n",            count, offset, status);    if (status == 2)        return count;    else if (status >= 0)        return -EIO;    else        return status;}
12-09 21:47
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