[PATCH net-next] net: aquantia: Fix build error wihtout CONFIG_PTP_1588_CLOCK

[YueHaibing]

If PTP_1588_CLOCK is n, building fails:

drivers/net/ethernet/aquantia/atlantic/aq_ptp.c: In function aq_ptp_adjfine:
drivers/net/ethernet/aquantia/atlantic/aq_ptp.c:279:11:
 error: implicit declaration of function scaled_ppm_to_ppb [-Werror=implicit-function-declaration]
           scaled_ppm_to_ppb(scaled_ppm));

Just cp scaled_ppm_to_ppb() from ptp_clock.c to fix this.

Fixes: 910479a9f793 ("net: aquantia: add basic ptp_clock callbacks")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 drivers/net/ethernet/aquantia/atlantic/aq_ptp.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
index 3ec0841..80c001d 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
@@ -262,6 +262,26 @@ static void aq_ptp_tx_timeout_check(struct aq_ptp_s *aq_ptp)
 	}
 }
 
+static s32 scaled_ppm_to_ppb(long ppm)
+{
+	/*
+	 * The 'freq' field in the 'struct timex' is in parts per
+	 * million, but with a 16 bit binary fractional field.
+	 *
+	 * We want to calculate
+	 *
+	 *    ppb = scaled_ppm * 1000 / 2^16
+	 *
+	 * which simplifies to
+	 *
+	 *    ppb = scaled_ppm * 125 / 2^13
+	 */
+	s64 ppb = 1 + ppm;
+	ppb *= 125;
+	ppb >>= 13;
+	return (s32) ppb;
+}
+
 /* aq_ptp_adjfine
  * @ptp: the ptp clock structure
  * @ppb: parts per billion adjustment from base
-- 
2.7.4