USB Host功能

i2C-6ULX-B底板上提供了两个USB Host接口(J5)，可以连接各类USB设备。这里以USB存储设备为例，插入USB存储设备到USB端口，系统中会提示有发现USB设备，同时还显示了当前设备在Linux系统中的设备名称为sda。并且该设备有一个分区，对应的设备为sda1。

usb 1-1.1: new high-speed USB device number 4 using ci_hdrc
usb-storage 1-1.1:1.0: USB Mass Storage device detected
scsi host1: usb-storage 1-1.1:1.0
scsi 1:0:0:0: Direct-Access     SanDisk  Ultra Fit        1.00 PQ: 0 ANSI: 6
sd 1:0:0:0: [sda] 60062500 512-byte logical blocks: (30.7 GB/28.6 GiB)
sd 1:0:0:0: [sda] Write Protect is off
sd 1:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
random: nonblocking pool is initialized
 sda: sda1
sd 1:0:0:0: [sda] Attached SCSI removable disk
FAT-fs (sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

默认系统会自动挂载USB设德至”/run/media”目录下。使用mount命令可以查看到相应的挂载目录。

# mount
/dev/root on / type ext4 (rw,relatime,data=ordered)
devtmpfs on /dev type devtmpfs (rw,relatime,size=89168k,nr_inodes=22292,mode=755)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)
/dev/sda1 on /run/media/sda1 type vfat (rw,relatime,gid=6,fmask=0007,dmask=0007,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

这里可以对/run/media/sda1目录进行读写文件操作，操作完成后可以使用umount命令对设备卸载后再拔出。

# umount /run/media/sda1