浅析frmware的加载和init通过netlink处理uevent事件的一般流程（转）当总线检测代id相macth的设备或者驱动时调用,wlan_probe=>wlan_probe=>wlan_add_card=>sbi_register_dev=>priv->hotplug_device = &func->dev;这样priv->hotplug_device就指向了/sys/bus/sdio/devices下的设备节点描述结构体接下来下载wlan的firmware固件驱动,=>wlan_init_fw=>request_firmware(&priv->firmware, fw_name, priv->hotplug_device);给priv->hotplug_device设备申请名字为fw_name的firmware数据,让后将结果放到&priv->firmware中,struct firmware {size_t size;u8 *data;};可以看到,如果应用层的程序成功load了firmware固件文件,那么firmware.data将指向固件数据,firmware.size为固件大小.module_param(fw_name, charp, 0);MODULE_PARM_DESC(fw_name, "Firmware name");这里可以看到fw_name是作为参数可以自由指定的,如果没有指定,那么将使用如下默认名：#define DEFAULT_FW_NAME "mrvl/sd8688.bin"=================================================================request_firmware=>_request_firmware=>fw_setup_device=>fw_register_device//添加临时download firmware的dev设备节点,注册该inode的class为=>fw_priv->attr_data = firmware_attr_data_tmpl;//文件属性操作函数集=>strlcpy(fw_priv->fw_id, fw_name, FIRMWARE_NAME_MAX);//拷贝参数就是我们的fw_name即默认的"mrvl/sd8688.bin"=>sysfs_create_bin_file(&f_dev->kobj, &fw_priv->attr_data);//创建DEVPATH/data文件,操作该文件的方法为firmware_attr_data_tmpl//这样init程序就可以打开这个DEVPATH/data文件,然后向这个DEVPATH/data文件写入firmware固件bin内容,然后kernel的driver就可以通过//firmware->data和firmware->size来读取有uevent处理程序init加载进来的firmware数据了[luther.gliethttp]=>f_dev->class = &firmware_class;=>if (uevent) kobject_uevent(&f_dev->kobj, KOBJ_ADD);发送uevent消息.=>wait_for_completion(&fw_priv->completion);等待完成static struct bin_attribute firmware_attr_data_tmpl = {.attr = {.name = "data", .mode = 0644},.size = 0,.read = firmware_data_read,.write = firmware_data_write,};=>firmware_data_write=>fw_realloc_buffer//类似realloc实现,释放原有的,申请新加的=>fw_priv->fw->data = new_data;=>kobject_uevent=>kobject_uevent_env/*devices_init=>devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);static struct kset_uevent_ops device_uevent_ops = {.filter =dev_uevent_filter,.name =dev_uevent_name,.uevent =dev_uevent,};=>dev_uevent=>dev->class->dev_ueventvoid device_initialize(struct device *dev){dev->kobj.kset = devices_kset;...}*/=>uevent_ops = kset->uevent_ops;//这里uevent_ops就指向device_uevent_ops了=>uevent_ops->uevent(kset, kobj, env);建立环境变量=>device_uevent_ops=>dev_uevent=>dev->class->dev_uevent就是firmware_class的dev_uevent,即：firmware_uevent=>firmware_uevent=>/*static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env){struct firmware_priv *fw_priv = dev_get_drvdata(dev);if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->fw_id))即默认的"mrvl/sd8688.bin"return -ENOMEM;if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))return -ENOMEM;return 0;}*/=>if (uevent_sock) { 那么通过netlink将该uevent事件广播出去,=>netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);=>在include/linux/autoconf.h中#define CONFIG_UEVENT_HELPER_PATH "/sbin/hotplug"=>但是我们的root文件系统/sbin/下没有hotplug这个文件,只有一个adbd程序,所以这样看来就不能运行了,所以这里应该将char uevent_helper[UEVENT_HELPER_PATH_LEN] = 清0才对,让if(uevent_helper[0])失败,进而不继续执行和hotplug的相关操作,但是现在autoconf.h中include/linux/autoconf.h#define CONFIG_NET 1#define CONFIG_HOTPLUG 1 仍然被设置成1,不知道为什么kernel team还要这样设置[luther.gliethttp]..所以我们的系统使用的是netlink接收事件广播,我的ubuntu8.04的/sbin下也没有找到hotplug这个文件,可能正如大家所说的,hotplug的诸多缺陷导致它已经淡出了linux世界,而天生丽质的netlink已经在linx世界中全面开花[luther.gliethttp].然后init进程开始处理这个firmware请求,init=>main=>handle_device_fd调用uevent的NETLINK_KOBJECT_UEVENT的socket处理函数=>parse_event=>handle_firmware_event=>pid = fork();子进程执行process_firmware_event=>process_firmware_event#define SYSFS_PREFIX "/sys"=>asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);//这里的uevent->path是parse_event函数解析时对应的"DEVPATH="节内容,也就是dev设备路径=>asprintf(&loading, "%sloading", root);//在该路径下创建loading文件=>asprintf(&data, "%sdata", root);//该路径下的data文件=>loading_fd = open(loading, O_WRONLY);//创建该loading文件,然后向其中写入"1"表示开始加载,加载成功写入"0",失败写入"-1".=>data_fd = open(data, O_WRONLY#define FIRMWARE_DIR "/system/lib/firmware" 原来路径是/etc/firmware,我的mrvl/sd8688.bin也放在那里,//但是虽然ramdisk虽然经过压缩,可是存储ramdisk.img的总大小才512k,所以不能将有可能不断扩大大小的firmware放到那里,//于是最近将init进程搜索路径改为"/system/lib/firmware".=>asprintf(&file, FIRMWARE_DIR"/%s", uevent->firmware);=>fw_fd = open(file, O_RDONLY);//打开通过uevent传递过来的firmware文件,然后拷贝过去=>load_firmware(fw_fd, loading_fd, data_fd))这样加载=================================================================#define module_param_named(name, value, type, perm) /param_check_##type(name, &(value)); /module_param_call(name, param_set_##type, param_get_##type, &value, perm); /__MODULE_PARM_TYPE(name, #type)#define module_param(name, type, perm)/module_param_named(name, name, type, perm)//对应param_check_##type检测参数类型函数如下,可以检测如下参数类型[luther.gliehttp]param_check_bool param_check_int param_check_short param_check_ushortparam_check_byte param_check_invbool param_check_uint param_check_proto_abbrevparam_check_charp param_check_long param_check_ulong param_check_scroll=================================================================比如usb通用驱动的使用,这样所有usb设备都可以通过serial方式进行访问,因为不是该usb设备专有的usb驱动,所以速度可能慢一些[luther.gliethttp].sudo insmod /lib/modules/2.6.22-14-generic/kernel/drivers/usb/serial/usbserial.ko vendor=0x8086 product=0xd001在drivers/usb/serial/generic.c驱动中,module_param(vendor, ushort, 0);MODULE_PARM_DESC(vendor, "User specified USB idVendor");module_param(product, ushort, 0);MODULE_PARM_DESC(product, "User specified USB idProduct");所以通过module_param可以方便的给ko驱动传递参数,很方便的咚咚,kernel那群人真能整[luther.gliethttp].
明天又会是新的一天，而我依然年轻。
