Starterware/AM3352: Mentor USB controller documentation

I am working on am3352, testing with starter kit, developing with sdk 3.3.0.4, and I posted some questions on how to access some registers. Hence I choose the tool/software Starterware again.
The old version is 2.4.25, and newer version is 4.4.41.

The old arch is powerpc. 

Hi Bin,

Can I use gadgetfs to achieve my goal? Looks like gadgetfs is more simple than sub gadget driver.

Is it possible to add control functions in gadgetfs to process messages sent from other application? I found the description in usb.c

- First, dev_config() is called when /dev/gadget/$CHIP is configured

+ *   (by writing configuration and device descriptors).  Afterwards it

+ *   may serve as a source of device events, used to handle all control

+ *   requests other than basic enumeration.

So, after config /dev/gadget/$CHIP, other application can send control message to the file descriptor of /dev/gadget/$CHIP.  Is it correct?

Also, could you tell me how to set up fifo and DMA while using gadgetfs?

Thank you.

Hi Bin,

I have tried gadgetfs and configfs on my starter kit. There is only one USB Micro B connection on board, which I also used as a UART connection for booting. I used configfs creates hid device on /dev/hidg0 .  When I tried to write to /dev/hidg0, sometimes I got return value of 0 from write(fd, bug,len) .  But most of the time, the system hang there. Similar thing happened for gadgetfs.  The following is my configfs commands and writing usb file is also attached.  The select() always returns 1, and /dev/hidg0 file descriptor is ready. I know I should write a real kbd report to this ep. But for simplicity, I only write a small buf to it.  

Could you help to find out what's the problem? Is it related to the fact that the only Micro B is converted to UART through a hub?

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# echo "0x1234" >idVendor

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# echo "0x5678" >idProduct

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# mkdir strings/0x409

root@m335x-evm:/sys/kernel/config/usb_gadget/g1# echo "foo1" >strings/0x409/maufacturer

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# echo "foo2" >strings/0x409/product

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# echo "foo3" >strings/0x409/seiialnumber

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# mkdir configs/c.1

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# mkdir configs/c.1/strings/0x409

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# mkdir functions/hid.kbd

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# ln -s functions/hid.kbd/ configs/c.1

root@am335x-evm:/sys/kernel/config/usb_gadget/g1# echo "musb-hdrc.0.auto" > UDC

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

#define NAME "/dev/hidg0"

int main(void)
{
	int fd;
	int status;
	char buf[4]={'1','2','3','\0'};
	fd_set rfds;
	int retval;
	
        fd=open(NAME, O_RDWR,0666);

	//fd=open(NAME, O_RDWR);

        FD_ZERO(&rfds);
        FD_SET(STDIN_FILENO, &rfds);
        FD_SET(fd, &rfds);
	int i = 2;
	while(i){
		retval = select(fd+1,&rfds,NULL,NULL,NULL);
		if(retval == -1)
		{
			i--;
			fprintf(stderr,"retval=-1\n");
			continue;
		}
		else if(retval >0){

			break;
		}
	}
	if(!i && (retval == -1)){
		fprintf(stderr, "fd not ready\n");
		close(fd);
		return -1;
	}

	if(FD_ISSET(fd, &rfds)){
		status = write (fd,buf,3);
		fprintf(stderr, "write to %s = %d\n",NAME,status);
		if(status<0){
			close(fd);
			return -1;
		}
	}
	close(fd);
	return 0;
}

Have you followed the kernel doc Documentation/usb/gadget_hid.txt to patch the kernel driver then test it with the hid_gadget_test application?

Yes, I followed /Documentation/usb/gadget_hid.txt to implement configfs. I didn't find the hid_gadget_test application, so I copied the example codes of hid_gadget_test from this file and create my own tempwrite.c  

On my Starter Kit, I can see /dev/hidgX is created. But on my booting PC where the Starter Kit connected to via usb cable,  no usb devices is enumerated, , except for ttyUSB0 and ttyUSB1. I checked before and after unplugged/ replugged the usb cable after enable/config  configfs. 

yingjie gu said:

I found out why it doesn't work. the attributes in functions/hid.kbd/ must be set before  UDC is linked to musb-hdrc.0.auto.

Glad you solved the issue. Yes, linking to the UDC has to be the very last step.

yingjie gu said:

Or in other words, does USB softreset affect the already in-effect configfs gadget functionality? 

I never tried it with configfs, but with the legacy usb gadget drivers, I found each usb controller has different behavior (caused by the different controller driver design I guess) - some require re-load the gadget driver, some don't.

But I don't remember how the musb controller on AM335x behaves. Please give it a test and let me know how it goes. But I am sure you don't have to "re-create" the configfs gadget, "unlink from UDC, do softreset, then link to UDC again" should be sufficient.

I haven't had my own customized board running yet, and I will test the USB softreset after it's done. 

I am trying to emulate HID and mass-storage by configfs. HID is working. But mass-storage has problem being emulated. 

I plugged in a USB disk on Starter Kit, and it's listed as /dev/sdb  /dev/sdb1

When run g_mass_storage directly with following attributes

 #modprobe g_mass_storage idVendor=0x1234 idProduct=0x5678 iManufacturer=gyjm iProduct=gyjp iSerialNumber=gyjs file=/dev/sdb1 stall=0 removable=1

'dmesg' on Starter Kit shows:

root@am335x-evm:/sys/kernel/config/usb_gadget# dmesg -T 

[Fri Oct 27 19:37:20 2017] Mass Storage Function, version: 2009/09/11

[Fri Oct 27 19:37:20 2017] LUN: removable file: (no medium)

[Fri Oct 27 19:37:20 2017] LUN: removable file: /dev/sdb1

[Fri Oct 27 19:37:20 2017] Number of LUNs=1

[Fri Oct 27 19:37:20 2017] g_mass_storage gadget: Mass Storage Gadget, version: 2009/09/11

[Fri Oct 27 19:37:20 2017] g_mass_storage gadget: g_mass_storage ready

[Fri Oct 27 19:37:21 2017] g_mass_storage gadget: high-speed config #1: Linux File-Backed Storage

And my PC reports: The disk you inserted was not readable by this computer.  But anyway, it's enumerated.

Then I configfs mass-storage with steps I believe is correct. HID is enumerated, but mass-storage is not. The following is a mass-storage related configuration. 

#mkdir functions/mass_storage.1

#echo 0 > functions/mass_storage.1/stall

#echo /dev/sdb1 > functions/mass_storage.1/lun.0/file

#echo 1 > functions/mass_storage.1/lun.0/removable

#ln -s functions/mass_storage.1 configs/c.1

#echo musb-hdrc.0.auto > UDC

I got the following dmesg:

[Fri Oct 27 19:08:25 2017] Mass Storage Function, version: 2009/09/11

[Fri Oct 27 19:08:25 2017] LUN: removable file: (no medium)

file is 'no medium'. I am not sure whether this is cause of the failure of enumeration.  On PC, dmesg shows no mass-storage.

Do you have any idea of this problem?