[PATCH v8 net-next 1/2] net: dsa: mv88e6xxx: allow reading FID when handling ATU violations

["Hans J. Schultz" <netdev@kapio-technology.com>]

The FID is needed to get hold of which VID was involved in a violation,
thus the need to be able to read the FID.

For convenience the function mv88e6xxx_g1_atu_op() has been used to read
ATU violations, but the function invalidates reading the fid, so to both
read ATU violations without zeroing the fid, and read the fid, functions
have been added to ensure both are done correctly.

Signed-off-by: Hans J. Schultz <netdev@kapio-technology.com>
---
 drivers/net/dsa/mv88e6xxx/global1_atu.c | 60 ++++++++++++++++++++++---
 1 file changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
index 40bd67a5c8e9..8a874b6fc8e1 100644
--- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
+++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
@@ -114,6 +114,19 @@ static int mv88e6xxx_g1_atu_op_wait(struct mv88e6xxx_chip *chip)
 	return mv88e6xxx_g1_wait_bit(chip, MV88E6XXX_G1_ATU_OP, bit, 0);
 }
 
+static int mv88e6xxx_g1_read_atu_violation(struct mv88e6xxx_chip *chip)
+{
+	int err;
+
+	err = mv88e6xxx_g1_write(chip, MV88E6XXX_G1_ATU_OP,
+				 MV88E6XXX_G1_ATU_OP_BUSY |
+				 MV88E6XXX_G1_ATU_OP_GET_CLR_VIOLATION);
+	if (err)
+		return err;
+
+	return mv88e6xxx_g1_atu_op_wait(chip);
+}
+
 static int mv88e6xxx_g1_atu_op(struct mv88e6xxx_chip *chip, u16 fid, u16 op)
 {
 	u16 val;
@@ -159,6 +172,41 @@ int mv88e6xxx_g1_atu_get_next(struct mv88e6xxx_chip *chip, u16 fid)
 	return mv88e6xxx_g1_atu_op(chip, fid, MV88E6XXX_G1_ATU_OP_GET_NEXT_DB);
 }
 
+static int mv88e6xxx_g1_atu_fid_read(struct mv88e6xxx_chip *chip, u16 *fid)
+{
+	u16 val = 0, upper = 0, op = 0;
+	int err = -EOPNOTSUPP;
+
+	if (mv88e6xxx_num_databases(chip) > 256) {
+		err = mv88e6xxx_g1_read(chip, MV88E6352_G1_ATU_FID, &val);
+		val &= 0xfff;
+		if (err)
+			return err;
+	} else {
+		err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_ATU_OP, &op);
+		if (err)
+			return err;
+		if (mv88e6xxx_num_databases(chip) > 64) {
+			/* ATU DBNum[7:4] are located in ATU Control 15:12 */
+			err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_ATU_CTL,
+						&upper);
+			if (err)
+				return err;
+
+			upper = (upper >> 8) & 0x00f0;
+		} else if (mv88e6xxx_num_databases(chip) > 16) {
+			/* ATU DBNum[5:4] are located in ATU Operation 9:8 */
+			upper = (op >> 4) & 0x30;
+		}
+
+		/* ATU DBNum[3:0] are located in ATU Operation 3:0 */
+		val = (op & 0xf) | upper;
+	}
+	*fid = val;
+
+	return err;
+}
+
 /* Offset 0x0C: ATU Data Register */
 
 static int mv88e6xxx_g1_atu_data_read(struct mv88e6xxx_chip *chip,
@@ -353,14 +401,12 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread_fn(int irq, void *dev_id)
 {
 	struct mv88e6xxx_chip *chip = dev_id;
 	struct mv88e6xxx_atu_entry entry;
-	int spid;
-	int err;
-	u16 val;
+	int err, spid;
+	u16 val, fid;
 
 	mv88e6xxx_reg_lock(chip);
 
-	err = mv88e6xxx_g1_atu_op(chip, 0,
-				  MV88E6XXX_G1_ATU_OP_GET_CLR_VIOLATION);
+	err = mv88e6xxx_g1_read_atu_violation(chip);
 	if (err)
 		goto out;
 
@@ -368,6 +414,10 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread_fn(int irq, void *dev_id)
 	if (err)
 		goto out;
 
+	err = mv88e6xxx_g1_atu_fid_read(chip, &fid);
+	if (err)
+		goto out;
+
 	err = mv88e6xxx_g1_atu_data_read(chip, &entry);
 	if (err)
 		goto out;
-- 
2.34.1