[PATCH v2 net] net: dsa: microchip: correct KSZ8795 static MAC table access

[Tristram.Ha]

From: Tristram Ha <Tristram.Ha@xxxxxxxxxxxxx>

The KSZ8795 driver code was modified to use on KSZ8863/73, which has
different register definitions.  Some of the new KSZ8795 register
information are wrong compared to previous code.

KSZ8795 also behaves differently in that the STATIC_MAC_TABLE_USE_FID
and STATIC_MAC_TABLE_FID bits are off by 1 when doing MAC table reading
than writing.  To compensate that a special code was added to shift the
register value by 1 before applying those bits.  This is wrong when the
code is running on KSZ8863, so this special code is only executed when
KSZ8795 is detected.

Fixes: 4b20a07e103f ("net: dsa: microchip: ksz8795: add support for ksz88xx chips")
Signed-off-by: Tristram Ha <Tristram.Ha@xxxxxxxxxxxxx>
Reviewed-by: Horatiu Vultur <horatiu.vultur@xxxxxxxxxxxxx>
---
v2
- Send to more maintainers.  Add review from Horatiu Vultur

v1
- Use correct commit for fixes

 drivers/net/dsa/microchip/ksz8795.c    | 8 +++++++-
 drivers/net/dsa/microchip/ksz_common.c | 8 ++++----
 drivers/net/dsa/microchip/ksz_common.h | 7 +++++++
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index 84d502589f8e..91aba470fb2f 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -506,7 +506,13 @@ static int ksz8_r_sta_mac_table(struct ksz_device *dev, u16 addr,
 		(data_hi & masks[STATIC_MAC_TABLE_FWD_PORTS]) >>
 			shifts[STATIC_MAC_FWD_PORTS];
 	alu->is_override = (data_hi & masks[STATIC_MAC_TABLE_OVERRIDE]) ? 1 : 0;
-	data_hi >>= 1;
+
+	/* KSZ8795 family switches have STATIC_MAC_TABLE_USE_FID and
+	 * STATIC_MAC_TABLE_FID definitions off by 1 when doing read on the
+	 * static MAC table compared to doing write.
+	 */
+	if (ksz_is_ksz87xx(dev))
+		data_hi >>= 1;
 	alu->is_static = true;
 	alu->is_use_fid = (data_hi & masks[STATIC_MAC_TABLE_USE_FID]) ? 1 : 0;
 	alu->fid = (data_hi & masks[STATIC_MAC_TABLE_FID]) >>
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 813b91a816bb..b18cd170ec06 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -331,13 +331,13 @@ static const u32 ksz8795_masks[] = {
 	[STATIC_MAC_TABLE_VALID]	= BIT(21),
 	[STATIC_MAC_TABLE_USE_FID]	= BIT(23),
 	[STATIC_MAC_TABLE_FID]		= GENMASK(30, 24),
-	[STATIC_MAC_TABLE_OVERRIDE]	= BIT(26),
-	[STATIC_MAC_TABLE_FWD_PORTS]	= GENMASK(24, 20),
+	[STATIC_MAC_TABLE_OVERRIDE]	= BIT(22),
+	[STATIC_MAC_TABLE_FWD_PORTS]	= GENMASK(20, 16),
 	[DYNAMIC_MAC_TABLE_ENTRIES_H]	= GENMASK(6, 0),
-	[DYNAMIC_MAC_TABLE_MAC_EMPTY]	= BIT(8),
+	[DYNAMIC_MAC_TABLE_MAC_EMPTY]	= BIT(7),
 	[DYNAMIC_MAC_TABLE_NOT_READY]	= BIT(7),
 	[DYNAMIC_MAC_TABLE_ENTRIES]	= GENMASK(31, 29),
-	[DYNAMIC_MAC_TABLE_FID]		= GENMASK(26, 20),
+	[DYNAMIC_MAC_TABLE_FID]		= GENMASK(22, 16),
 	[DYNAMIC_MAC_TABLE_SRC_PORT]	= GENMASK(26, 24),
 	[DYNAMIC_MAC_TABLE_TIMESTAMP]	= GENMASK(28, 27),
 	[P_MII_TX_FLOW_CTRL]		= BIT(5),
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 28444e5924f9..a4de58847dea 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -601,6 +601,13 @@ static inline void ksz_regmap_unlock(void *__mtx)
 	mutex_unlock(mtx);
 }
 
+static inline bool ksz_is_ksz87xx(struct ksz_device *dev)
+{
+	return dev->chip_id == KSZ8795_CHIP_ID ||
+	       dev->chip_id == KSZ8794_CHIP_ID ||
+	       dev->chip_id == KSZ8765_CHIP_ID;
+}
+
 static inline bool ksz_is_ksz88x3(struct ksz_device *dev)
 {
 	return dev->chip_id == KSZ8830_CHIP_ID;
-- 
2.17.1