Hello

I want to write to some specific physical address in the system memory space. I am writing a driver for it. I am using following functions

in module_init:
check_region() to check the availability of that specific physical address.
request_mem_region() to request the memory resource from the kernel in case of successful check_region(). The function request_mem_region() returns success which means (as far as I assume) that the resource has been allocated to my driver.

in write function
If the request_region() returns success then I must be able to write to that memory address just freely.
For example: *(char *)myphysicaladdr = some value

But when I open the driver file from /dev and write a charater to it, segmentation fault occurs. Kindly somebody help me what should I do?

outb() is used to write to an i/o port address. Kindly tell me is there any function to write to physical address?

regards,
Atif Shabir

No; request_region() just gives you ownership of some address range on the (PCI) bus.
To map that range into the CPU's address space, call ioremap(), and don't forget to call iounmap() later for releasing that mapping.
To access that memory, use readb/w/l/q() and writeb/w/l/q().