浅析/dev/bus/usb/下的major主设备号189和动态253对应的内核驱动

浅析/dev/bus/usb/下的major主设备号189和动态253对应的内核驱动

drivers/usb/core/devio.c
usb_devio_init
==>

const struct file_operations usbdev_file_operations = {
    .owner =     THIS_MODULE,
    .llseek =    usbdev_lseek,
    .read =        usbdev_read,
    .poll =        usbdev_poll,
    .ioctl =    usbdev_ioctl,
    .open =        usbdev_open,
    .release =    usbdev_release,
};

usbdev_ioctl
==>
#define USBDEVFS_CONTROL           _IOWR('U', 0, struct usbdevfs_ctrltransfer)
#define USBDEVFS_BULK              _IOWR('U', 2, struct usbdevfs_bulktransfer)
case USBDEVFS_CONTROL:
    proc_control(ps, p);

luther@gliethttp:~$ ll /dev/bus/usb/001/
total 0
crw-rw-r-- 1 root root 189, 4 2009-07-15 08:10 005
crw-rw-r-- 1 root root 189, 5 2009-07-15 08:12 006
crw-rw-r-- 1 root root 189, 0 2009-07-15 15:17 001

至于/dev/usbdev*主设备号253,是每个usb设备具有的端点控制接口
generic_probe
==>usb_create_sysfs_dev_files
==*>usb_create_ep_files(dev, &udev->ep0, udev);
==**>ep_dev->dev.devt = MKDEV(usb_endpoint_major, ep_dev->minor); // 这里usb_endpoint_major就是253

init_endpoint_class
==>usb_endpoint_major_init();
#define MAX_ENDPOINT_MINORS (64*128*32) // 最多观测endpoint数目
==*>alloc_chrdev_region(&dev, 0, MAX_ENDPOINT_MINORS, "usb_endpoint");
==*>usb_endpoint_major = MAJOR(dev); // 将alloc_chrdev_region动态申请的major号添进去.

luther@gliethttp:/vobs/libusb$ ll /dev/usbdev*
crw-rw---- 1 root root 253,  9 2009-07-14 18:48 /dev/usbdev1.5_ep00
crw-rw---- 1 root root 253,  6 2009-07-14 18:48 /dev/usbdev1.5_ep01
crw-rw---- 1 root root 253,  7 2009-07-14 18:48 /dev/usbdev1.5_ep82
crw-rw---- 1 root root 253,  8 2009-07-14 18:48 /dev/usbdev1.5_ep83
crw-rw---- 1 root root 253, 10 2009-07-14 19:33 /dev/usbdev2.19_ep81
crw-rw---- 1 root root 253, 11 2009-07-14 19:33 /dev/usbdev2.19_ep00
crw-rw---- 1 root root 253, 14 2009-07-14 19:33 /dev/usbdev2.20_ep00
crw-rw---- 1 root root 253, 12 2009-07-14 19:33 /dev/usbdev2.20_ep81
crw-rw---- 1 root root 253, 13 2009-07-14 19:33 /dev/usbdev2.20_ep02
crw-rw---- 1 root root 253,  0 2009-07-15 02:03 /dev/usbdev1.1_ep81
crw-rw---- 1 root root 253,  1 2009-07-15 02:03 /dev/usbdev1.1_ep00
crw-rw---- 1 root root 253,  3 2009-07-15 02:03 /dev/usbdev2.1_ep00
crw-rw---- 1 root root 253,  2 2009-07-15 02:03 /dev/usbdev2.1_ep81
crw-rw---- 1 root root 253,  5 2009-07-15 02:03 /dev/usbdev2.2_ep00
crw-rw---- 1 root root 253,  4 2009-07-15 02:03 /dev/usbdev2.2_ep81

luther@gliethttp:~$ ls /sys/class/usb_endpoint
usbdev1.1_ep00  usbdev1.3_ep81  usbdev2.1_ep00  usbdev3.1_ep81  usbdev5.1_ep00  usbdev6.1_ep81
usbdev1.1_ep81  usbdev1.5_ep00  usbdev2.1_ep81  usbdev4.1_ep00  usbdev5.1_ep81  usbdev7.1_ep00
usbdev1.3_ep00  usbdev1.5_ep81  usbdev3.1_ep00  usbdev4.1_ep81  usbdev6.1_ep00  usbdev7.1_ep81