delay_cycles
delay = delay_cycles(ppd, srate_mbs, dw_len);
delay_cycles = cycles_per_us * keypad->scan_interval;
WARN_ON(delay_cycles >= (1 << 16)); /* Overflow */
delay_cycles &= 0xffff;
val |= delay_cycles << 16; /* Delay between scans */
unsigned long val = 0, cycles_per_us, delay_cycles, row_delay_cycles;