Hello, All. As we all know that the standard linux kernel does not allow us to access physical address of devices, so the physical address must be converted to virtual address before any IO operation. In my disign, the cs8900a is configured for IO mode, its bus physical address is 0x1001_0000, and its default IO base address is 0x300, ARM9(Cirrus Logic EP9302) processor linux kernel 2.4.21. Now, problem is, how can I get the virtual address of the cs8900a unde my device driver?
The code below can't work correctly.
... static unsigned int virt_base;
if(check_mem_region(0x10010300, 0x10)){ printk(KERN_INFO "CS8900A: memory already in use\n"); } else request_mem_region(0x10010300, 0x10, "CS8900A"); } virt_base = (unsigned int)ioremap(0x10010300, 0x10); // 16 bytes
// get signature writew(0x0000, virt_base+0x0a); mdelay(100); printk(KERN_INFO "CS8900A : 0x%lx\n", readw(virt_base+0x0c)); ...
I appreciate anyone who help this.