+/*
+ * Table of syncrates that don't follow the "divisible by 4"
+ * rule. This table will be expanded in future SCSI specs.
+ */
+static struct {
+ u_int period_factor;
+ u_int period; /* in 100ths of ns */
+} scsi_syncrates[] = {
+ { 0x08, 625 }, /* FAST-160 */
+ { 0x09, 1250 }, /* FAST-80 */
+ { 0x0a, 2500 }, /* FAST-40 40MHz */
+ { 0x0b, 3030 }, /* FAST-40 33MHz */
+ { 0x0c, 5000 } /* FAST-20 */
+};
+
+/*
+ * Return the frequency in kHz corresponding to the given
+ * sync period factor.
+ */
+static u_int
+ahc_calc_syncsrate(u_int period_factor)
+{
+ int i;
+ int num_syncrates;
+
+ num_syncrates = sizeof(scsi_syncrates) / sizeof(scsi_syncrates[0]);
+ /* See if the period is in the "exception" table */
+ for (i = 0; i < num_syncrates; i++) {
+
+ if (period_factor == scsi_syncrates[i].period_factor) {
+ /* Period in kHz */
+ return (100000000 / scsi_syncrates[i].period);
+ }
+ }
+
+ /*
+ * Wasn't in the table, so use the standard
+ * 4 times conversion.
+ */
+ return (10000000 / (period_factor * 4 * 10));
+}
+
+