sys/class 下文件节点创建实例

1 创建读版本号节点  

 firmware_class = class_create(THIS_MODULE, "ms-touchscreen-msg20xx");

    if (IS_ERR(firmware_class))

        pr_err("Failed to create class(firmware)!\n");

    firmware_cmd_dev = device_create(firmware_class, NULL, 0, NULL, "device");

    if (IS_ERR(firmware_cmd_dev))

        pr_err("Failed to create device(firmware_cmd_dev)!\n");

    if (device_create_file(firmware_cmd_dev, &dev_attr_version) < 0)
        pr_err("Failed to create device file(%s)!\n", dev_attr_version.attr.name);

static ssize_t firmware_version_show(struct device *dev,

                                     struct device_attribute *attr, char *buf)

{

    _msg_GetVersion();

    if(fw_version == NULL)

    {   

        fw_version = kzalloc(sizeof(*fw_version)*8, GFP_KERNEL);

    }

    sprintf(fw_version, "%04d%04d", curr_ic_major, curr_ic_minor);

    TPD_DEBUG_UPDATE("*** firmware_version_show fw_version = %s***\n", fw_version);

    return sprintf(buf, "%s\n", fw_version);

}

static ssize_t firmware_version_store(struct device *dev,

                                      struct device_attribute *attr, const char *buf, size_t size)

{ 

    _msg_GetVersion();

    if(fw_version == NULL)

    {   

        fw_version = kzalloc(sizeof(*fw_version)*8, GFP_KERNEL);

    }

    sprintf(fw_version, "%04d%04d", curr_ic_major, curr_ic_minor);

    TPD_DEBUG_UPDATE("*** fw_version = %s ***\n", fw_version);

#ifdef CONFIG_ENABLE_FIRMWARE_DATA_LOG
restore_firmware_mode_to_debug_mode();

#endif //CONFIG_ENABLE_FIRMWARE_DATA_LOG

    if(buf != NULL)

        TPD_DEBUG_UPDATE("buf = %c ***\n", buf[0]);

    return size;

}

static DEVICE_ATTR(version,0664, firmware_version_show, firmware_version_store);