文章目錄
- Summary
- Basics
- Using S3C2440 as a USB Host
- Using S3C2440 as a USB Disk
- Using the Gadget Serial Driver
- Reference
Summary
Tested on Embedded Linux S3C2440 target board to be configured as USB device, like USB mass storage and serial cable, the test result was successful. And tried to test S3C2440 board as USB Host, I didn’t get successful result.
Basics
S3C2440 supports 2-port USB host interface as follows,
- OHCI Rev 1.0 compatible.
- USB Rev 1.1 compatible
- Two down stream ports.
-
Support for both LowSpeed and Full Speed USB devices.
S3C2440A device controller support:
- Full speed USB device controller compatible with USB specification v1.1
- DMA interface for bulk transfer.
-
Five endpoints with FIFO:
EP0: 16 bytes(register)
EP1: 128 byte IN/OUT FIFO (dual port asynchronous RAM): interrupt or DMA.
EP2: 128 byte IN/OUT FIFO (dual port asynchronous RAM): interrupt or DMA.
EP3: 128 byte IN/OUT FIFO (dual port asynchronous RAM): interrupt or DMA.
EP4: 128 byte IN/OUT FIFO (dual port asynchronous RAM): interrupt or DMA.
S3C2440A board has two USB ports: the port with a type A connector works as a USB host; the other with a Type B connector works as a USB peripheral. Both USB host controller and UDC (USB device controller) are regarded as platform device and their drivers are registered as platform driver.
Source code of USB host controller driver is
linux-3.8.7/drivers/usb/host/ohci-s3c2410.c
.
The UDC driver reads/writes the registers of the UDC and reads/writes the FIFOs of the endpoints. Gadget drivers sit on top of the UDC dirver, and use the service it provides. A UDC driver must impelment a set of function to manipulate endpoints and gadget, as well as to register and unregister a gadget driver. They are defined in the file
linux-3.8.7/include/linux/usb/gadget.h
.
The UDC of S3C2440A is integrated on the S3C2440 chip and hence is regarded as a platform device. Its driver is a platform driver. Source code of the UDC drier for S3C2440 is
linux-3.8.7/drivers/usb/gadget/s3c2410_udc.c
. It is for all the S3C2410 based boards.
The UDC driver maintains a request queue for each of the 5 endpoints, a gadget driver puts request to the queues by calling
queue()
. When the request is completed and the request has a callback function, the UDC driver dequeues the requests and calls its complete function.
Using S3C2440 as a USB Host
In Linux 3.8.7 source code folder,
make menuconfig
.
In
Linux/arm 3.8.7 Kernel Configuration
-->
Device Drivers --->
, -->
USB support
<*> Support for Host-side USB
[*] USB announce new devices
<*> Configure to install usb device driver in Kernel. In
Device Drivers --->
, then go to
SCSI device support --->
,
<*> SCSI device support
<*> Under
[*] USB support --->
, select,
[*] USB support ---> Configure to support the file system, go to
File systems --->
, select,
DOS/FAT/NT Filesystems --->
<*> MSDOS fs support
<*> VFAT (Windows-95) fs support
(437) Default codepage for FAT
(iso8859-1) Default iocharset for FAT
<*> NTFS file system support
[*] NTFS debugging support
[*] NTFS write Change from
(utf8) Default iocharset for to
(iso8859-1) Default iocharset for Configure the language support, go to
File systems --->
, select,
-*- Native language support --->
(utf8) Default NLS Option
<*> Codepage 437 (United States, Canada)
<*> NLS ISO 8859-1 (Latin 1; Western European Languages) To be able to support Chinese characters, go to
Device Drivers --->
,
Input device support --->
,
<*> Go to
HID support --->
then,
USB HID support --->
,
<*> After S3C2440 startup, inserted into one USB thumb driver, the S3C2440 cannot detect the USB thumb driver, the test result failed.
Using S3C2440 as a USB Disk
We use part of the NAND as a USB Disk. Edit the source code
linux-3.8.7/arch/arm/mach-s3c24xx/mach-mini2440.c
, allocate 50M to the root file system and the rest for the USB disk, it is around 195M.
[root@localhost mach-s3c24xx]# pwd
/home/iot/mini2440/linux-3.8.7/arch/arm/mach-s3c24xx
[root@localhost mach-s3c24xx]# vim mach-mini2440.c 0x03200000 is around 50M, it is for root file system.
static struct mtd_partition mini2440_default_nand_part[] __initdata = {
[0] = {
.name = "u-boot",
.size = SZ_256K,
.offset = 0,
},
[1] = {
.name = "u-boot-env",
.size = SZ_128K,
.offset = SZ_256K,
},
[2] = {
.name = "kernel",
/* 5 megabytes, for a kernel with no modules
* or a uImage with a ramdisk attached */
.size = 0x00600000,
.offset = SZ_256K + SZ_128K,
},
[3] = {
.name = "root",
.offset = SZ_256K + SZ_128K + 0x00600000,
/*.size = MTDPART_SIZ_FULL,*/
.size = 0x03200000,
},
[4] = {
.name = "udisk",
.offset = SZ_256K + SZ_128K + 0x00600000 + 0x03200000,
.size = MTDPART_SIZ_FULL,
},
}; Configure busybox,
[root@localhost busybox-1.19.4]# pwd
/home/iot/mini2440/busybox-1.19.4
[root@localhost busybox-1.19.4]# make menuconfig Under
Linux System Utilities --->
, change the configuration,
[*] mkfs_vfat
, then save the configuration.
Compile and install busybox,
[root@localhost busybox-1.19.4]# make clean
CLEAN applets
CLEAN .tmp_versions _install
CLEAN busybox busybox_unstripped.map busybox_unstripped.out busybox_unstripped busybox.links .kernelrelease
[root@localhost busybox-1.19.4]# make
[root@localhost busybox-1.19.4]# make install Generate the root file system,
[root@localhost rootfilesystem]# pwd
/home/iot/mini2440/rootfilesystem
[root@localhost rootfilesystem]#
[root@localhost rootfilesystem]# vim create_rootfs_bash.sh Edit file,
Add following line
mkdir Before the line,
echo "---------Copy from busybox, rootfs-base, libs -----------" Add the following line,
cp Before following line,
chown -R root.root ../rootfs Change directory to linux-3.8.7,
[root@localhost rootfilesystem]# cd /home/iot/mini2440/linux-3.8.7/
[root@localhost linux-3.8.7]# pwd
/home/iot/mini2440/linux-3.8.7
[root@localhost linux-3.8.7]# Configure the Linux kernel to support USB Gadget,
[root@localhost linux-3.8.7]# make menuconfig Under
Linux/arm 3.8.7 Kernel Configuration
, go to
Device Drivers --->
, then go to
[*] USB support --->
, and
<*> USB Gadget Support --->
.
Configure as the following as show below,
--- USB Gadget Support
[ ] Debugging messages (DEVELOPMENT)
[ ] Debugging information files (DEVELOPMENT)
[ ] Debugging information files in debugfs (DEVELOPMENT)
(2) Maximum VBUS Power usage (2-500 mA)
(2) Number of storage pipeline buffers
USB Peripheral Controller --->
<M> USB Gadget Drivers
< > Gadget Zero (DEVELOPMENT)
<M> Ethernet Gadget (with CDC Ethernet support)
[*] RNDIS support (NEW)
[ ] Ethernet Emulation Model (EEM) support (NEW)
< > Network Control Model (NCM) support
< > Gadget Filesystem
< > Function Filesystem
<M> Mass Storage Gadget
<M> Serial Gadget (with CDC ACM and CDC OBEX support)
< > Printer Gadget
< > CDC Composite Device (Ethernet and ACM)
< > CDC Composite Device (ACM and mass storage)
< > Multifunction Composite Gadget
< > HID Gadget
< > EHCI Debug Device Gadget
< > Enter USB Peripheral Controller -->,
USB Peripheral Controller --->
, it is the same menu further go down, and select
<*> S3C2410 USB Device Controller
.
< > Faraday FUSB300 USB Peripheral Controller
< > Renesas R8A66597 USB Peripheral Controller
<*> S3C2410 USB Device Controller
[ ] S3C2410 udc debug messages (NEW)
< > S3C2416, S3C2443 and S3C2450 USB Device Controller
< > Marvell USB2.0 Device Controller
< > Renesas M66592 USB Peripheral Controller
< > PLX NET2272
< > Dummy HCD (DEVELOPMENT) Exit to
Device Drivers
, Enter into
<*> Memory Technology Device (MTD) support --->
,
Select as below items,
--- Memory Technology Device (MTD) support
< > MTD tests support (DANGEROUS)
< > RedBoot partition table parsing
[ ] Command line partition table parsing
< > ARM Firmware Suite partition parsing
< > TI AR7 partitioning support
*** User Modules And Translation Layers ***
<*> Direct char device access to MTD devices
-*- Common interface to block layer for MTD 'translation layers'
<*> Caching block device access to MTD devices
<*> FTL (Flash Translation Layer) support
<*> NFTL (NAND Flash Translation Layer) support
[*] Write support for NFTL
< > INFTL (Inverse NAND Flash Translation Layer) support
< > Resident Flash Disk (Flash Translation Layer) support
< > NAND SSFDC (SmartMedia) read only translation layer
< > SmartMedia/xD new translation layer
< > Log panic/oops to an MTD buffer
RAM/ROM/Flash chip drivers --->
Mapping drivers for chip access --->
Self-contained MTD device drivers --->
[ ] NAND ECC Smart Media byte order
<*> NAND Device Support --->
< > OneNAND Device Support --->
LPDDR flash memory drivers --->
< > Enable UBI - Unsorted block images ---> Exit to
Linux/arm 3.8.7 Kernel Configuration
.
Select
File systems ---> DOS/FAT/NT Filesystems ---> <*> VFAT (Windows-95) fs support
.
Change the Default codepage for FAT to 437,
From
(936) Default codepage for to
(437) Default codepage for Select
File systems --> -*- Native language support ---> (utf8) Default NLS Option
, select below options,
<*> Codepage 437 (United States, Canada)
<*> We will use initramfs and not the rootfs in the NAND flash as we tested the YAFFS2 file system before, we need to change it back.
Enter
General setup --->
and scroll down to
"[*] Initial RAM filesystem and RAM disk (initramfs/initrd) support"
.
Set the Initramfs open source file(s) to
"initramfs.cpio"
, exit from
"General setup"
.
Exit and save the configuration.
Compile the kernel and modules.
[root@localhost linux-3.8.7]# make clean
[root@localhost linux-3.8.7]# make
[root@localhost linux-3.8.7]# make modules_install
INSTALL drivers/char/foo.ko
INSTALL drivers/usb/gadget/g_ether.ko
INSTALL drivers/usb/gadget/g_mass_storage.ko
INSTALL drivers/usb/gadget/g_serial.ko
INSTALL drivers/usb/gadget/libcomposite.ko
INSTALL fs/nfs/nfs_layout_nfsv41_files.ko
DEPMOD 3.8.7-FriendlyARM
[root@localhost linux-3.8.7]# Create root file system,
[root@localhost rootfilesystem]# pwd
/home/iot/mini2440/rootfilesystem
[root@localhost rootfilesystem]# ./create_rootfs_bash.sh
------Create rootfs --------
/home/iot/mini2440/rootfilesystem/rootfs /home/iot/mini2440/rootfilesystem
--------Create root,dev....----------
---------Copy from busybox, rootfs-base, libs -----------
---------make node dev/console dev/null-----------------
mknod: ‘/dev/ptmx’: File exists
17654 blocks
/home/iot/mini2440/rootfilesystem Recompile the kernel for the newly created root file system, it is to incorporate the newly created the root file system.
[root@localhost rootfilesystem]# cd /home/iot/mini2440/linux-3.8.7/
[root@localhost linux-3.8.7]# pwd
/home/iot/mini2440/linux-3.8.7
[root@localhost linux-3.8.7]# make Download the new kernel into the S3C2440 board, and boot it up,
Now the kernel is too big, need to increase the kernel partition size, 6M size is not enough, need to increase to 7M, the error when downloading the zImage was as below,
##### FriendlyARM BIOS 2.0 for 2440 #####
[x] format NAND FLASH for Linux
[v] Download vivi
[k] Download linux kernel
[y] Download root_yaffs image
[a] Absolute User Application
[n] Download Nboot for WinCE
[l] Download WinCE boot-logo
[w] Download WinCE NK.bin
[d] Download & Run
[z] Download zImage into RAM
[g] Boot linux from RAM
[f] Format the nand flash
[b] Boot the system
[s] Set the boot parameters
[u] Backup NAND Flash to HOST through USB(upload)
[r] Restore NAND Flash from HOST through USB
[q] Goto shell of vivi
[i] Version: 1026-2K
Enter your selection: k
USB host is connected. Waiting a download.
Length of file is too big : 6500184 > 6291456
Failed downloading file Change the partition, increase the kernel partition to 0x00700000
[root@localhost mach-s3c24xx]# pwd
/home/iot/mini2440/linux-3.8.7/arch/arm/mach-s3c24xx
[root@localhost mach-s3c24xx]# vim mach-mini2440.c Modify the source code,
linux-3.8.7/arch/arm/mach-s3c24xx/mach-mini2440.c
/* NAND Flash on MINI2440 board */
static struct mtd_partition mini2440_default_nand_part[] __initdata = {
[0] = {
.name = "u-boot",
.size = SZ_256K,
.offset = 0,
},
[1] = {
.name = "u-boot-env",
.size = SZ_128K,
.offset = SZ_256K,
},
[2] = {
.name = "kernel",
/* 5 megabytes, for a kernel with no modules
* or a uImage with a ramdisk attached */
.size = 0x00700000,
.offset = SZ_256K + SZ_128K,
},
[3] = {
.name = "root",
.offset = SZ_256K + SZ_128K + 0x00700000,
/*.size = MTDPART_SIZ_FULL,*/
.size = 0x03200000,
},
[4] = {
.name = "udisk",
.offset = SZ_256K + SZ_128K + 0x00700000 + 0x03200000,
.size = MTDPART_SIZ_FULL,
},
}; Recompile the kernel,
[root@localhost mach-s3c24xx]# cd /home/iot/mini2440/linux-3.8.7/
[root@localhost linux-3.8.7]# pwd
/home/iot/mini2440/linux-3.8.7
[root@localhost linux-3.8.7]# Since the newly generated zImage is more than 6M, we need to change the setting, using command part add kernel 0x00060000 0x00700000 0, the first number in command is the starting address of kernel stored in the NAND flash. The second number in the command is the number of bytes the bootloader will copy from kernel partition to RAM, it must be greater than the size of the zImage.
The new table is as below,
| Name | Offset | Size |
| vivi “u-boot” | 0x000000000000 | 0x000000040000 |
| param “u-boot-env” | 0x000000040000 | 0x000000020000 |
| “kernel” | 0x000000060000 | 0x000000700000 |
| “root” | 0x000000760000 | 0x00003fa80000 |
Refer to this article: Embedded Linux S3C2440 Profiling , use
vivi
command line to modify the part table, and refer to this article Embedded Linux S3C2440 – Partitions an FileSytem (YAFFS2) to change
linux_cmd_line
parameter.
##### FriendlyARM BIOS 2.0 for 2440 #####
[x] format NAND FLASH for Linux
[v] Download vivi
[k] Download linux kernel
[y] Download root_yaffs image
[a] Absolute User Application
[n] Download Nboot for WinCE
[l] Download WinCE boot-logo
[w] Download WinCE NK.bin
[d] Download & Run
[z] Download zImage into RAM
[g] Boot linux from RAM
[f] Format the nand flash
[b] Boot the system
[s] Set the boot parameters
[u] Backup NAND Flash to HOST through USB(upload)
[r] Restore NAND Flash from HOST through USB
[q] Goto shell of vivi
[i] Version: 1026-2K
Enter your selection: q
Supervivi> part show
Number of partitions: 4
name : offset size flag
------------------------------------------------------------
vivi : 0x00000000 0x00040000 0
param : 0x00040000 0x00020000 0
kernel : 0x00060000 0x00600000 0
root : 0x00660000 0x3fa80000 0
Supervivi> part del root
deleted 'root' partition
Supervivi> part del kernel
deleted 'kernel' partition
Supervivi> part show
Number of partitions: 2
name : offset size flag
------------------------------------------------------------
vivi : 0x00000000 0x00040000 0
param : 0x00040000 0x00020000 0
Supervivi> part add kernel 0x00060000 0x00700000 0
kernel: offset = 0x00060000, size = 0x00700000, flag = 0
Supervivi> part add root 0x00760000 0x3fa80000 0
root: offset = 0x00760000, size = 0x3fa80000, flag = 0
Supervivi> part show
Number of partitions: 4
name : offset size flag
------------------------------------------------------------
vivi : 0x00000000 0x00040000 0
param : 0x00040000 0x00020000 0
kernel : 0x00060000 0x00700000 0
root : 0x00760000 0x3fa80000 0
Supervivi> help part
Usage:
part help
part add <name> <offset> <size> <flag> -- Add a mtd partition entry
part del <name> -- Delete a mtd partition entry
part reset -- Reset mtd parition table
part save -- Save mtd partition table
part show -- Display mtd partition table
Supervivi> part save
Found block size = 0x00020000
Erasing... ... done
Writing... ... done
Written 49152 bytes
Supervivi> Change the linux command line to
noinitrd init=/init console=ttySAC0,115200
.
Supervivi> param show
Number of parameters: 9
name : hex integer
-------------------------------------------------------------
mach_type : 000007cf 1999
media_type : 00000003 3
boot_mem_base : 30000000 805306368
baudrate : 0001c200 115200
xmodem : 00000001 1
xmodem_one_nak : 00000000 0
xmodem_initial_timeout : 000493e0 300000
xmodem_timeout : 000f4240 1000000
boot_delay : 01000000 16777216
Linux command line: root=/dev/mtdblock3 console=ttySAC0,115200
Supervivi> help param
Usage:
param help -- Help aout 'param' command
param reset -- Reset parameter table to default table
param save -- Save parameter table to flash memeory
param set <name> <value> -- Reset value of parameter
param set linux_cmd_line "..." -- set boot parameter
param show -- Display parameter table
Supervivi> param set linux_cmd_line "noinitrd init=/init console=ttySAC0,115200"
Change linux command line to "noinitrd init=/init console=ttySAC0,115200"
Supervivi> param save
Found block size = 0x00020000
Erasing... ... done
Writing... ... done
Written 49152 bytes
Saved vivi private data
Supervivi> param show
Number of parameters: 9
name : hex integer
-------------------------------------------------------------
mach_type : 000007cf 1999
media_type : 00000003 3
boot_mem_base : 30000000 805306368
baudrate : 0001c200 115200
xmodem : 00000001 1
xmodem_one_nak : 00000000 0
xmodem_initial_timeout : 000493e0 300000
xmodem_timeout : 000f4240 1000000
boot_delay : 01000000 16777216
Linux command line: noinitrd init=/init console=ttySAC0,115200
Supervivi> Now donwload the kernel zImage again, the downloading of the new zImage was successful.
At Host side,
[root@localhost mini2440]# ./download_image.sh
csum = 0x5f4a
send_file: addr = 0x33f80000, len = 0x00632f58
Error downloading program
[root@localhost mini2440]# At board side,
##### FriendlyARM BIOS 2.0 for 2440 #####
[x] format NAND FLASH for Linux
[v] Download vivi
[k] Download linux kernel
[y] Download root_yaffs image
[a] Absolute User Application
[n] Download Nboot for WinCE
[l] Download WinCE boot-logo
[w] Download WinCE NK.bin
[d] Download & Run
[z] Download zImage into RAM
[g] Boot linux from RAM
[f] Format the nand flash
[b] Boot the system
[s] Set the boot parameters
[u] Backup NAND Flash to HOST through USB(upload)
[r] Restore NAND Flash from HOST through USB
[q] Goto shell of vivi
[i] Version: 1026-2K
Enter your selection: k
USB host is connected. Waiting a download.
Now, Downloading [ADDRESS:30000000h,TOTAL:6500194]
RECEIVED FILE SIZE: 6500194 (19KB/S, 331S)
Downloaded file at 0x30000000, size = 6500184 bytes
Found block size = 0x00640000
Erasing... ... done
Writing... ... done Boot up the S3C2440 board.
Create fat32 filesystem on
/dev/mtdblock4
.
[root@mini2440 /]# mkfs.vfat /dev/mtdblock4 Connect the USB type B port of the board to the USB tyep A port of the PC.
On the S3C2440 board, load the driver module and use
/dev/mtdblock4
as the storage file.
[root@mini2440 /]# modprobe /lib/modules/3.8.7-FriendlyARM/kernel/drivers/usb/gadget/g_mass_storage.ko file=/dev/mtdblock4 stall=0 removable=1
g_mass_storage gadget: Mass Storage Function, version: 2009/09/11
g_mass_storage gadget: Number of LUNs=1
lun0: LUN: removable file: /dev/mtdblock4
g_mass_storage gadget: Mass Storage Gadget, version: 2009/09/11
g_mass_storage gadget: userspace failed to provide iSerialNumber
g_mass_storage gadget: g_mass_storage ready
g_mass_storage gadget: full-speed config #1: Linux File-Backed Storage
g_mass_storage gadget: full-speed config #1: Linux File-Backed Storage At host side, the PC will detect the USB device as a File-Backed Storage Gadget.
Below was the message showed on the Fedora by typing command
dmesg
. Mount the storage and copy the file
download_image.sh
into the storage.
[root@localhost mini2440]# dmesg
......
[29682.804613] usb 1-3: new full-speed USB device number 12 using ohci_hcd
[29683.266058] usb 1-3: New USB device found, idVendor=0525, idProduct=a4a5
[29683.266062] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[29683.266064] usb 1-3: Product: Mass Storage Gadget
[29683.266067] usb 1-3: Manufacturer: Linux 3.8.7-FriendlyARM with s3c2410_udc
[29683.393339] Initializing USB Mass Storage driver...
[29683.395592] usb-storage 1-3:1.0: Quirks match for vid 0525 pid a4a5: 10000
[29683.395614] scsi3 : usb-storage 1-3:1.0
[29683.397864] usbcore: registered new interface driver usb-storage
[29683.397867] USB Mass Storage support registered.
[29684.438713] scsi 3:0:0:0: Direct-Access Linux File-CD Gadget 0308 PQ: 0 ANSI: 2
[29684.442797] sd 3:0:0:0: Attached scsi generic sg2 type 0
[29684.479111] sd 3:0:0:0: [sdb] 406784 512-byte logical blocks: (208 MB/198 MiB)
[29684.487498] sd 3:0:0:0: [sdb] Write Protect is off
[29684.487502] sd 3:0:0:0: [sdb] Mode Sense: 0f 00 00 00
[29684.500274] sd 3:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[29684.577987] sdb:
[29684.649574] sd 3:0:0:0: [sdb] Attached SCSI removable disk
......
[root@localhost mini2440]# ls /dev/sdb
/dev/sdb
[root@localhost mini2440]# mount /dev/sdb /mnt/
[root@localhost mini2440]# ls
buildroot-2013.02 busybox-1.19.4 config-files download_image.sh download_image_yaffs.sh initramfs.cpio linux-3.8.7 myapp ready-built rootfilesystem rootfs s3c2410_boot_usb
[root@localhost mini2440]# cp download_image.sh /mnt
[root@localhost mini2440]# ls /mnt/
download_image.sh System Volume Information
[root@localhost mini2440]# umount /mnt
[root@localhost mini2440]#
[root@localhost mini2440]# df -h
Filesystem Size Used Avail Use% Mounted on
rootfs 26G 22G 3.2G 88% /
devtmpfs 366M 0 366M 0% /dev
tmpfs 375M 68K 375M 1% /dev/shm
tmpfs 375M 4.0M 371M 2% /run
tmpfs 375M 0 375M 0% /sys/fs/cgroup
/dev/mapper/fedora-root 26G 22G 3.2G 88% /
tmpfs 375M 24K 375M 1% /tmp
/dev/sda1 485M 49M 411M 11% /boot
Linux 120G 111G 8.8G 93% /media/sf_Linux
/dev/sdb 196M 2.5K 196M 1% /mnt
[root@localhost mini2440]# At S3C2440 board side, remove the module
g_mass_storage
, and mount the
/dev/mtdblock4
, it was checked the file
download_image.sh
after checking on the S3C2440 board.
[root@mini2440 /]# rmmod g_mass_storage
[root@mini2440 /]# mount -t vfat /dev/mtdblock4 /mnt/udisk
[root@mini2440 /]# ls /mnt/udisk
System Volume Information download_image.sh
[root@mini2440 /]# cat /mnt/udisk/download_image.sh
#!/bin/sh We can also check the USB gadget disk on the Windows system, just connect the host PC windows system, the result is as below.
Detected the S3C2440 - USB Gadget as 195M memory size.
Detected the S3C2440 - USB Gadget as and the file
download_image.sh
is inside.
Using the Gadget Serial Driver
The gadget serial driver talks over USB to either a CDC ACM driver or a generic USB serial driver running on a host PC. On the S3C2440 device side Linux system, the gadget serial driver looks like a serial device. On the host-side system, the gadget serial device looks like a CDC ACM compliant class device or a simple vendor specific device with bulk in and bulk out endpoints, and it is treated similarly to other serial devices.
We have generated the gadget serial driver module
linux-3.8.7/drivers/usb/gadget/g_serial.ko
.
On the S3C2440 side, load the driver module, by default it will be loaded as ACM device as below shows.
[root@mini2440 /root]# modprobe /lib/modules/3.8.7-FriendlyARM/kernel/drivers/usb/gadget/g_serial.ko
g_serial gadget: Gadget Serial v2.4
g_serial gadget: g_serial ready
g_serial gadget: full-speed config #2: CDC ACM config
gerial gadget: full-speed config #2: CDC ACM config We find a new device node
/dev/ttyGS0
is created.
[root@mini2440 /root]# ls /dev/ttyG*
/dev/ttyGS0
[root@mini2440 /root]# And the host PC detects the new device and a new device node
/dev/ttyACM0
is created, the
dmsg
command shows as below,
[root@localhost linux-3.8.7]# dmesg
......
[30844.512119] sd 4:0:0:0: [sdb] Synchronizing SCSI cache
[30844.512143] sd 4:0:0:0: [sdb]
[30844.512145] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[32160.418124] usb 1-3: new full-speed USB device number 14 using ohci_hcd
[32160.888156] usb 1-3: New USB device found, idVendor=0525, idProduct=a4a7
[32160.888161] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[32160.888163] usb 1-3: Product: Gadget Serial v2.4
[32160.888165] usb 1-3: Manufacturer: Linux 3.8.7-FriendlyARM with s3c2410_udc
[32160.944340] cdc_acm 1-3:2.0: This device cannot do calls on its own. It is not a modem.
[32160.944378] cdc_acm 1-3:2.0: ttyACM0: USB ACM device
[32160.960056] usbcore: registered new interface driver cdc_acm
[32160.960059] cdc_acm: USB Abstract Control Model driver for Use
lsusb
command to show the detail of the device, and send string
2222222222
to the serial device
/dev/ttyACM0
.
[root@localhost linux-3.8.7]# ls /dev/ttyA*
/dev/ttyACM0
[root@localhost ~]#
[root@localhost linux-3.8.7]# lsusb
Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
Bus 001 Device 008: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 001 Device 014: ID 0525:a4a7 Netchip Technology, Inc. Linux-USB Serial Gadget (CDC ACM mode)
Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
[root@localhost linux-3.8.7]# echo 2222222222 > /dev/ttyACM0 [root@mini2440 /root]# cat /dev/ttyGS0