UsbSoftwareInterface

USB Software Interface

Linux PSP

About this page

This page describes the software interface available in Linux kernel on different kernel versions. Please refer the config option which matches with kernel version of release you are using.

Linux v3.2

sysfs interface

Serial Number	sysfs attribute	Description
1	mode	The entry /sys/devices/platform/musb_hdrc.X/mode is a read-only entry. It will show the state of the OTG state machine.
2	vbus	The entry /sys/devices/platform/musb_hdrc.X/vbus is a write-only entry. It is used to set the VBUS timeout value during OTG. If the current OTG state is a_wait_bcon then then urb submission is disabled.

procfs

The procfs entry /proc/driver/musb_hdrc.X is used to control the driver behavior as well as check the status of the driver.

Serial Number	Desired test	Command to be used
1	To see the uses of procfs interface	echo "?" > /proc/driver/musb_hdrc.X
2	To switch on the session OR to switch on the Vbus while acting as host	echo "F" > /proc/driver/musb_hdrc.X

musb driver debugfs

To use the debugfs feature of kernel and musb, you need to enable the kernel debugfs option through menuconfig, as shown below

      Menuconfig->kernel hacking -->
            [ ] Enable unused/obsolete exported symbols                                            
            [*] Debug Filesystem                                                                   
            [ ] Run 'make headers_check' when building vmlinux      
            [*] Kernel debugging               

mount the debug file system (debugfs)

     #mount -t debugfs none /sys/kernel/debug/

musb driver TEST-MODE debugfs support

Serial Number	Desired Test	Command to be used
1	Force musb to host mode	echo "force host" > /sys/kernel/debug/musb/testmode
2	Force musb to full speed	echo "force full-speed" > /sys/kernel/debug/musb/testmode
3	Force musb to high speed	echo "force high-speed" > /sys/kernel/debug/musb/testmode
4	Send test packet	echo "test packet" > /sys/kernel/debug/musb/testmode
5	Generate test K pattern	echo "test K" > /sys/kernel/debug/musb/testmode
5	Generate test J pattern	echo "test J" > /sys/kernel/debug/musb/testmode
6	Generate test SE0 NAK pattern	echo "test SE0 NAK" > /sys/kernel/debug/musb/testmode