Hi,

I am new to linux-kernel and am using kernel 3.1.6 and working on
arm-SemiHosting(through USB) drivers.

We are using SemiHosting to exchange/transfer data from the arm-board to
the PC.

What is SemiHosting?
SemiHosting is a way to tranfer/exchange data b/w arm-board and the PC.
We have an application USBConsole.exe running on the windows machine that
controls/interfaces with the USB uint on the
arm board.

Board details ?

Using ARM926e-js processor with 128MB SDRAM., Clock-33Mhz

SDRAM Size = 128M

CONFIG_PAGE_OFFSET = 0xc0000000
CONFIG_PHYS_OFFSET= 0x80000000
Kernel Lowmem = 32M including 8M for initramfs (starting from  24M to

32M).

HighMEM is not configured.
Vmalloc_start =     end address of LowMem (i.e 0xC200000)
VMALLOC_END =  Vmalloc_start + 64M  = 0xC6000000

The SemiHosting(USB) drivers have read(); write(); seek(); functionalities
along with an InitUSB function that initializes the semihosting USB
hardware unit on the arm board.

Is this a USB host controller, or a device controller?  Do you have a
pointer to where this code is somewhere so we can see what it does?
It is neither.,it is a hardware unit on the arm-board with a register set
accesed by both arm and
the USBConsole.exe on the PC.This USBConsole.exe sets these registers
appropriately.

We are using kernel ioremap() function for accessing the USB register set,
which is remaped to malloc section.

Are these are the USB controller's register set for a host device, or a
"gadget"?

Functionality in  semihosting init (InitUSB) function ?

1. We send header command to hostPC via USB DMA operation  by setting few
USB registers.

Setting them where?
Setting them on the board memory(USB register memory after virtually mapped)

    USB DMA takes the start address of the header and it?s size and these
two params (addr, size) are set into corresponding USB registers.

    The USB transfer is enabled by setting USB_EN register to appropriate
value.



2.After header transfer  acknowledgement from hostPC should be received.

  As acknowledgement , hostPC should set INTC_USB register, we poll for
this register and once this is set we are done with the initialisation.

I wanted to test if the InitUSB function is working as expected. So I
called this function in the start_kernel(after Console_Init()).

As this function is just setting few registers and polling for few
registers., I io_remaped this register set in the InitUSB function..

But the INTC_USB register that is set by the hostPC as acknowledgement is
not getting set and the code is never coming out of the while loop.

  Can a USBConsole.exe running on the windows machine access register on
the arm-board running on the linux.??

As mentioned I am calling the Init_USB function in the start_kernel(after
Console_Init()).

On Fri, Mar 9, 2012 at 8:34 PM, Greg KH [off-list ref] wrote:

On Fri, Mar 09, 2012 at 03:49:57PM +0530, KARTHIK SEKURU wrote:

quoted

Hi,

I am new to linux-kernel and am using kernel 3.1.6 and working on
arm-SemiHosting(through USB) drivers.

We are using SemiHosting to exchange/transfer data from the arm-board to
the PC.

What is SemiHosting?

quoted

Board details ?

Using ARM926e-js processor with 128MB SDRAM., Clock-33Mhz

SDRAM Size = 128M

CONFIG_PAGE_OFFSET = 0xc0000000
CONFIG_PHYS_OFFSET= 0x80000000
Kernel Lowmem = 32M including 8M for initramfs (starting from  24M to

32M).

quoted

HighMEM is not configured.
Vmalloc_start =     end address of LowMem (i.e 0xC200000)
VMALLOC_END =  Vmalloc_start + 64M  = 0xC6000000

The SemiHosting(USB) drivers have read(); write(); seek();

functionalities

quoted

along with an InitUSB function that initializes the semihosting USB
hardware unit on the arm board.

Is this a USB host controller, or a device controller?  Do you have a
pointer to where this code is somewhere so we can see what it does?

quoted

We are using kernel ioremap() function for accessing the USB register

set,

quoted

which is remaped to malloc section.

Are these are the USB controller's register set for a host device, or a
"gadget"?

quoted

Functionality in  semihosting init (InitUSB) function ?

1. We send header command to hostPC via USB DMA operation  by setting few
USB registers.

Setting them where?

quoted

    USB DMA takes the start address of the header and it?s size and these
two params (addr, size) are set into corresponding USB registers.

    The USB transfer is enabled by setting USB_EN register to appropriate
value.



2.After header transfer  acknowledgement from hostPC should be received.

  As acknowledgement , hostPC should set INTC_USB register, we poll for
this register and once this is set we are done with the initialisation.

I wanted to test if the InitUSB function is working as expected. So I
called this function in the start_kernel(after Console_Init()).

As this function is just setting few registers and polling for few
registers., I io_remaped this register set in the InitUSB function..

But the INTC_USB register that is set by the hostPC as acknowledgement is
not getting set and the code is never coming out of the while loop.

Now, I wanted to know if the place from where the InitUSB() function is
called is the culprit and due to it if I am not receiving acknowledgement
from the PC.

As mentioned I am calling the Init_USB function in the start_kernel(after
Console_Init()).

I think a pointer to the code would be the easiest for us to understand
exactly what is going on here.  Also, USB specific questions are best
asked on the linux-usb at vger.kernel.org mailing list, have you tried
there?

thanks,

greg k-h

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