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-rw-r--r--drivers/ptp/ptp_qoriq.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c
index beb5f74944cd..08f4cf0ad9e3 100644
--- a/drivers/ptp/ptp_qoriq.c
+++ b/drivers/ptp/ptp_qoriq.c
@@ -189,15 +189,16 @@ int ptp_qoriq_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
tmr_add = ptp_qoriq->tmr_add;
adj = tmr_add;
- /* calculate diff as adj*(scaled_ppm/65536)/1000000
- * and round() to the nearest integer
+ /*
+ * Calculate diff and round() to the nearest integer
+ *
+ * diff = adj * (ppb / 1000000000)
+ * = adj * scaled_ppm / 65536000000
*/
- adj *= scaled_ppm;
- diff = div_u64(adj, 8000000);
- diff = (diff >> 13) + ((diff >> 12) & 1);
+ diff = mul_u64_u64_div_u64(adj, scaled_ppm, 32768000000);
+ diff = DIV64_U64_ROUND_UP(diff, 2);
tmr_add = neg_adj ? tmr_add - diff : tmr_add + diff;
-
ptp_qoriq->write(&regs->ctrl_regs->tmr_add, tmr_add);
return 0;