[RFC PATCH 2/2] net: macb: Fix SUBNS increment and increase resolution

[Harini Katakam]

The subns increment register has 24 bits as follows:
RegBit[15:0] = Subns[23:8]; RegBit[31:24] = Subns[7:0]

Fix the same in the driver and increase sub ns resolution to the
best capable, 24 bits. This should be the case on all GEM versions
that this PTP driver supports.

Signed-off-by: Harini Katakam <harini.katakam@xxxxxxxxxx>
---
 drivers/net/ethernet/cadence/macb.h     | 6 +++++-
 drivers/net/ethernet/cadence/macb_ptp.c | 5 ++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 0993949..0fb51cd 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -499,7 +499,11 @@
 
 /* Bitfields in TISUBN */
 #define GEM_SUBNSINCR_OFFSET			0
-#define GEM_SUBNSINCR_SIZE			16
+#define GEM_SUBNSINCRL_OFFSET			24
+#define GEM_SUBNSINCRL_SIZE			8
+#define GEM_SUBNSINCRH_OFFSET			0
+#define GEM_SUBNSINCRH_SIZE			16
+#define GEM_SUBNSINCR_SIZE			24
 
 /* Bitfields in TI */
 #define GEM_NSINCR_OFFSET			0
diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
index 46d9cdf..75dc4f8 100644
--- a/drivers/net/ethernet/cadence/macb_ptp.c
+++ b/drivers/net/ethernet/cadence/macb_ptp.c
@@ -115,7 +115,10 @@ static int gem_tsu_incr_set(struct macb *bp, struct tsu_incr *incr_spec)
 	 * to take effect.
 	 */
 	spin_lock_irqsave(&bp->tsu_clk_lock, flags);
-	gem_writel(bp, TISUBN, GEM_BF(SUBNSINCR, incr_spec->sub_ns));
+	/* RegBit[15:0] = Subns[23:8]; RegBit[31:24] = Subns[7:0] */
+	gem_writel(bp, TISUBN, GEM_BF(SUBNSINCRL, incr_spec->sub_ns) |
+		   GEM_BF(SUBNSINCRH, (incr_spec->sub_ns >>
+			  GEM_SUBNSINCRL_SIZE)));
 	gem_writel(bp, TI, GEM_BF(NSINCR, incr_spec->ns));
 	spin_unlock_irqrestore(&bp->tsu_clk_lock, flags);
 
-- 
2.7.4