int ide_system_bus_speed ( void);
ide_system_bus_speed returns what we think is the system VESA/PCI bus speed (in MHz). This is used for calculating interface PIO timings. The default is 40 for known PCI systems, 50 otherwise. The ``idebus=xx'' parameter can be used to override this value. The actual value to be used is computed/displayed the first time through. Drivers should only use this as a last resort.
Returns a guessed speed in MHz.