DESK-MP1-L/Peripherals/USB OTG

History
Issue Date	Notes
2023/08/02	DESK-MP1-L-1.0.0 release

Peripheral USB OTG

Device tree configuration

Here below an example of device tree configuration used on standard DAVE's kit for the ETRA SOM

OTG port can be forced using the 4th DIP-switch (see the DIP settings section on the Boot configurations page):

• OFF: otg mode, the connected peripheral has its ID pin properly set and it is able to change the working mode according to the pin logic value
• ON: host force the host mode.

From kernel device tree stm32mp157a-dcsb5000dd1r.dts:

...
...
&usbotg_hs{
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&usb_otg_hs_pins_mx>;
	pinctrl-1 = <&usb_otg_hs_sleep_pins_mx>;
	status = "okay";

	/* USER CODE BEGIN usbotg_hs */
	compatible = "st,stm32mp15-hsotg", "snps,dwc2";
	phys = <&usbphyc_port1 0>;
	phy-names = "usb2-phy";
	vbus-supply = <&vbus_otg>;
	dr_mode = "otg";
	/* USER CODE END usbotg_hs */
};

&usbphyc_port1{
	status = "okay";

	/* USER CODE BEGIN usbphyc_port1 */
	phy-supply = <&vdd_usb>;
	/* USER CODE END usbphyc_port1 */
};
...
...
pinctrl {
	...
	...
	usb_otg_hs_pins_mx: usb_otg_hs_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('A', 10, ANALOG)>; /* USB_OTG_HS_ID */
		};
	};

	usb_otg_hs_sleep_pins_mx: usb_otg_hs_sleep_mx-0 {
		pins {
			pinmux = <STM32_PINMUX('A', 10, ANALOG)>; /* USB_OTG_HS_ID */
		};
	};
    ...
    ...
};
...
...

Accessing the peripheral

Linux messages at boot time

root@desk-mp1:~# dmesg | grep otg
[    2.202854] vbus_otg: supplied by bst_out
[    2.591726] dwc2 49000000.usb-otg: supply vusb_d not found, using dummy regulator
[    2.598534] dwc2 49000000.usb-otg: supply vusb_a not found, using dummy regulator
[    2.746347] dwc2 49000000.usb-otg: EPs: 9, dedicated fifos, 952 entries in SPRAM
[    2.753429] dwc2 49000000.usb-otg: DWC OTG Controller
[    2.757541] dwc2 49000000.usb-otg: new USB bus registered, assigned bus number 1
[    2.765060] dwc2 49000000.usb-otg: irq 74, io mem 0x49000000
[   13.812830] dwc2 49000000.usb-otg: bound driver configfs-gadget

Usage in Host mode

When a USB 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.)

[  109.857720] usb 1-1: new high-speed USB device number 2 using dwc2
[  110.117799] usb-storage 1-1:1.0: USB Mass Storage device detected
[  110.127163] scsi host1: usb-storage 1-1:1.0
[  111.447577] scsi 1:0:0:0: Direct-Access     ADATA    USB Flash Drive  1100 PQ: 0 ANSI: 0 CCS
[  111.462507] sd 1:0:0:0: [sdb] 7913472 512-byte logical blocks: (4.05 GB/3.77 GiB)
[  111.471019] sd 1:0:0:0: Attached scsi generic sg1 type 0
[  111.491495] sd 1:0:0:0: [sdb] Write Protect is off
[  111.495087] sd 1:0:0:0: [sdb] Mode Sense: 43 00 00 00
[  111.501814] sd 1:0:0:0: [sdb] No Caching mode page found
[  111.505814] sd 1:0:0:0: [sdb] Assuming drive cache: write through
[  111.520046]  sdb: sdb1
[  111.528131] sd 1:0:0:0: [sdb] Attached SCSI removable disk

Usage with mass-storage

root@desk-mp1:~# 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, 0.111651 s, 150 MB/s
root@desk-mp1:~# mkfs.ext4 /tmp/mass
mke2fs 1.46.5 (30-Dec-2021)
Discarding device blocks: done
Creating filesystem with 16384 1k blocks and 4096 inodes
Filesystem UUID: 354cc3e0-2b27-4573-b1d6-d7fb99c3a535
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@desk-mp1:~# mkdir -p /tmp/loop
root@desk-mp1:~# mount /tmp/mass /tmp/loop
root@desk-mp1:~# dd if=/dev/urandom of=/tmp/loop/pippo bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes (10 MB, 10 MiB) copied, 0.715313 s, 14.7 MB/s
root@desk-mp1:~# md5sum /tmp/loop/pippo
31743a261ce01c14f9c28f6529caba72  /tmp/loop/pippo
root@desk-mp1:~# umount /tmp/loop
root@desk-mp1:~# echo "" > /sys/kernel/config/usb_gadget/g1/UDC
root@desk-mp1:~# rm /sys/kernel/config/usb_gadget/g1/configs/c.1/rndis.0
root@desk-mp1:~# mkdir /sys/kernel/config/usb_gadget/g1/functions/mass_storage.1
root@desk-mp1:~# echo "/tmp/mass" > /sys/kernel/config/usb_gadget/g1/functions/mass_storage.1/lun.0/file
root@desk-mp1:~# ln -s /sys/kernel/config/usb_gadget/g1/functions/mass_storage.1 /sys/kernel/config/usb_gadget/g1/configs/c.1
root@desk-mp1:~# echo 49000000.usb-otg > /sys/kernel/config/usb_gadget/g1/UDC 
root@desk-mp1:~# lsblk
NAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda            8:0    1   16M  0 disk 
mmcblk1      179:0    0 14.9G  0 disk 
|-mmcblk1p1  179:1    0  256K  0 part 
|-mmcblk1p2  179:2    0  256K  0 part 
|-mmcblk1p3  179:3    0  256K  0 part 
|-mmcblk1p4  179:4    0  256K  0 part 
|-mmcblk1p5  179:5    0    4M  0 part 
|-mmcblk1p6  179:6    0    4M  0 part 
|-mmcblk1p7  179:7    0  512K  0 part 
|-mmcblk1p8  179:8    0   64M  0 part /boot
|-mmcblk1p9  179:9    0   16M  0 part /vendor
|-mmcblk1p10 179:10   0    2G  0 part /
`-mmcblk1p11 179:11   0  128M  0 part /usr/local
mmcblk2      179:16   0  3.5G  0 disk 
mmcblk2boot0 179:32   0    2M  1 disk 
mmcblk2boot1 179:48   0    2M  1 disk 
root@desk-mp1:~# mkdir -p /tmp/usb
root@desk-mp1:~# mount /dev/sda /tmp/usb/
root@desk-mp1:~# md5sum /tmp/usb/pippo
31743a261ce01c14f9c28f6529caba72  /tmp/usb/pippo

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