[PATCH net-next 4/7] net: dsa: mv88e6xxx: wait for AVB Busy bit

[Vivien Didelot]

The AVB is not an indirect table using an Update bit, but a unit using
a Busy bit. This means that we must ensure that this bit is cleared
before setting it and wait until it gets cleared again after writing
an operation. Reflect that.

Signed-off-by: Vivien Didelot <vivien.dide...@gmail.com>
---
 drivers/net/dsa/mv88e6xxx/global2_avb.c | 29 +++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/global2_avb.c 
b/drivers/net/dsa/mv88e6xxx/global2_avb.c
index 116b8cf5a6e3..657783e043ff 100644
--- a/drivers/net/dsa/mv88e6xxx/global2_avb.c
+++ b/drivers/net/dsa/mv88e6xxx/global2_avb.c
@@ -11,6 +11,8 @@
  *     Brandon Streiff <brandon.stre...@ni.com>
  */
 
+#include <linux/bitfield.h>
+
 #include "global2.h"
 
 /* Offset 0x16: AVB Command Register
@@ -27,17 +29,33 @@
 /* mv88e6xxx_g2_avb_read -- Read one or multiple 16-bit words.
  * The hardware supports snapshotting up to four contiguous registers.
  */
+static int mv88e6xxx_g2_avb_wait(struct mv88e6xxx_chip *chip)
+{
+       int bit = __bf_shf(MV88E6352_G2_AVB_CMD_BUSY);
+
+       return mv88e6xxx_g2_wait_bit(chip, MV88E6352_G2_AVB_CMD, bit, 0);
+}
+
 static int mv88e6xxx_g2_avb_read(struct mv88e6xxx_chip *chip, u16 readop,
                                 u16 *data, int len)
 {
        int err;
        int i;
 
+       err = mv88e6xxx_g2_avb_wait(chip);
+       if (err)
+               return err;
+
        /* Hardware can only snapshot four words. */
        if (len > 4)
                return -E2BIG;
 
-       err = mv88e6xxx_g2_update(chip, MV88E6352_G2_AVB_CMD, readop);
+       err = mv88e6xxx_g2_write(chip, MV88E6352_G2_AVB_CMD,
+                                MV88E6352_G2_AVB_CMD_BUSY | readop);
+       if (err)
+               return err;
+
+       err = mv88e6xxx_g2_avb_wait(chip);
        if (err)
                return err;
 
@@ -57,11 +75,18 @@ static int mv88e6xxx_g2_avb_write(struct mv88e6xxx_chip 
*chip, u16 writeop,
 {
        int err;
 
+       err = mv88e6xxx_g2_avb_wait(chip);
+       if (err)
+               return err;
+
        err = mv88e6xxx_g2_write(chip, MV88E6352_G2_AVB_DATA, data);
        if (err)
                return err;
 
-       return mv88e6xxx_g2_update(chip, MV88E6352_G2_AVB_CMD, writeop);
+       err = mv88e6xxx_g2_write(chip, MV88E6352_G2_AVB_CMD,
+                                MV88E6352_G2_AVB_CMD_BUSY | writeop);
+
+       return mv88e6xxx_g2_avb_wait(chip);
 }
 
 static int mv88e6352_g2_avb_port_ptp_read(struct mv88e6xxx_chip *chip,
-- 
2.22.0