+/*
+ * Compute the PIO modes available for this device. This is not as
+ * trivial as it seems if we must consider early devices correctly.
+ *
+ * FIXME: pre IDE drive timing (do we care ?).
+ */
+
+static unsigned int ata_pio_modes(struct ata_device *adev)
+{
+ u16 modes;
+
+ /* Usual case. Word 53 indicates word 88 is valid */
+ if (adev->id[ATA_ID_FIELD_VALID] & (1 << 2)) {
+ modes = adev->id[ATA_ID_PIO_MODES] & 0x03;
+ modes <<= 3;
+ modes |= 0x7;
+ return modes;
+ }
+
+ /* If word 88 isn't valid then Word 51 holds the PIO timing number
+ for the maximum. Turn it into a mask and return it */
+ modes = (2 << (adev->id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;
+ return modes;
+}
+