DESK-XZ7-L/Peripherals/USB OTG

History
Issue Date	Notes
2024/01/23	DESK-XZ7-L-1.x.x release
2025/06/12	DESK-XZ7-L 2.x.x release

Peripheral USB OTG

Device tree configuration

Here below an example of device tree configuration used on standard DAVE's kit for the BORA, BORA Xpress and BORA Lite:

From bora.dtsi:

...
...

/ {

...
...
    usb_phy0: phy0@e0002000{
        compatible = "ulpi-phy";
        #phy-cells = <0x00>;
        reg = <0xe0002000 0x1000>;
        view-port = <0x170>;
        drv-vbus;
    };

...
...

};

...
...

&usb0 {
    dr_mode = "otg";
    usb-phy = <&usb_phy0>;

};

...
...

Accessing the peripheral

Linux messages in host mode

When a USB2.0 peripheral is inserted, in the following example a memory mass storage device, the kernel recognizes the device (i.e. class, vendor id, product id, etc.)

[ 3649.090990] ci_hdrc ci_hdrc.0: EHCI Host Controller
[ 3649.091077] ci_hdrc ci_hdrc.0: new USB bus registered, assigned bus number 1
[ 3649.118348] ci_hdrc ci_hdrc.0: USB 2.0 started, EHCI 1.00
[ 3649.119094] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 6.06
[ 3649.119148] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 3649.119185] usb usb1: Product: EHCI Host Controller
[ 3649.119214] usb usb1: Manufacturer: Linux 6.6.40-xilinx-g2b7f6f70a62a ehci_hcd
[ 3649.119241] usb usb1: SerialNumber: ci_hdrc.0
[ 3649.121015] hub 1-0:1.0: USB hub found
[ 3649.121168] hub 1-0:1.0: 1 port detected
[ 3649.808344] usb 1-1: new high-speed USB device number 2 using ci_hdrc
[ 3650.010627] usb 1-1: New USB device found, idVendor=0781, idProduct=5591, bcdDevice= 1.00
[ 3650.010686] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3650.010723] usb 1-1: Product:  SanDisk 3.2Gen1
[ 3650.010752] usb 1-1: Manufacturer:  USB
[ 3650.010778] usb 1-1: SerialNumber: 0101c87a64b5cb45bccaae1bd784c1bad724ebe2453b86693086a660b9568077c3bd000000000000000000005c22d5f9ff81320091558107a1aaf0ca
[ 3650.013156] usb-storage 1-1:1.0: USB Mass Storage device detected
[ 3650.015390] scsi host1: usb-storage 1-1:1.0
[ 3651.068638] usb 1-1: Get one byte OTG status failed
[ 3651.070809] scsi 1:0:0:0: Direct-Access      USB      SanDisk 3.2Gen1 1.00 PQ: 0 ANSI: 6
[ 3651.073643] sd 1:0:0:0: Attached scsi generic sg0 type 0
[ 3651.083081] sd 1:0:0:0: [sdb] 240353280 512-byte logical blocks: (123 GB/115 GiB)
[ 3651.084294] sd 1:0:0:0: [sdb] Write Protect is off
[ 3651.084361] sd 1:0:0:0: [sdb] Mode Sense: 43 00 00 00
[ 3651.085540] sd 1:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 3651.098041]  sdb: sdb1
[ 3651.098893] sd 1:0:0:0: [sdb] Attached SCSI removable disk
[ 3652.215600] FAT-fs (sdb1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

Additional information

If the root file system configuration does not automatically mount the partition, it is possible to mount the device using the following command:

root@bora:~# mkdir -p /mnt/usb
root@bora:~# mount /dev/sda1 /mnt/usb
root@bora:~# ls -la /mnt/usb/
total 110916
drwxrwx--- 3 root disk     32768 Jan  1  1970 .
drwxr-xr-x 5 root root      4096 Jun 12 11:47 ..
-rwxrwx--- 1 root disk 104857600 Jun 12 10:21 linux_testfile.txt
-rwxrwx--- 1 root disk        13 Mar  9  2018 uboot_testfile.txt
root@bora:~#

Accessing the device

Usage with mass-storage

root@bora:~# dd if=/dev/zero of=/tmp/mass count=16 bs=1M
16+0 records in
16+0 records out
16777216 bytes (17 MB, 16 MiB) copied, 0.111122 s, 151 MB/s
root@bora:~# mkfs.ext4 /tmp/mass
mke2fs 1.47.0 (5-Feb-2023)
Discarding device blocks: done
Creating filesystem with 16384 1k blocks and 4096 inodes
Filesystem UUID: 03af7a9e-aa46-4041-8ef4-aa062ac8d1a8
Superblock backups stored on blocks:
        8193

Allocating group tables: done
Writing inode tables: done
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

root@bora:~# mkdir -p /tmp/loop
root@bora:~# mount /tmp/mass /tmp/loop
root@bora:~# echo "Hello from desk-xz7-l" > /tmp/loop/usb.txt
root@bora:~# umount /tmp/loop
root@bora:~#

then insert the g_mass_storage kernel module driver enabling an Windows PC to see it as a removable device

root@bora:~# modprobe --first-time g_mass_storage file=/tmp/mass iSerialNumber=USBOTGCHECK

Once the USB cable is connected to the PC, the kernel prints the following messages:

[  110.975128] Mass Storage Function, version: 2009/09/11
[  110.975153] LUN: removable file: (no medium)
[  110.975314] LUN: file: /var/volatile/tmp/mass
[  110.975333] Number of LUNs=1
[  110.975610] g_mass_storage gadget.0: Mass Storage Gadget, version: 2009/09/11
[  110.975632] g_mass_storage gadget.0: g_mass_storage ready

and the Windows PC activate the driver and the disk is available as a Drive Unit (with the usb.txt file available).