WINDOW_LENGTH
if (len > (WINDOW_LENGTH - (from & WINDOW_MASK)))
thislen = WINDOW_LENGTH-(from & WINDOW_MASK);
if (len > (WINDOW_LENGTH - (to & WINDOW_MASK)))
thislen = WINDOW_LENGTH-(to & WINDOW_MASK);
iomapadr = ioremap(WINDOW_START, WINDOW_LENGTH);
WINDOW_START, WINDOW_START+WINDOW_LENGTH-1 );
#define WINDOW_MASK (WINDOW_LENGTH-1)