rt2400pci_bbp_read
.read = rt2400pci_bbp_read,
r4 = rt2400pci_bbp_read(rt2x00dev, 4);
r1 = rt2400pci_bbp_read(rt2x00dev, 1);
bbp = rt2400pci_bbp_read(rt2x00dev, 39);
value = rt2400pci_bbp_read(rt2x00dev, 0);