On Fri, Mar 09, 2012 at 03:49:57PM +0530, KARTHIK SEKURU wrote: > 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? > 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? > 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? > 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@xxxxxxxxxxxxxxx mailing list, have you tried there? thanks, greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
